阅读说明：本技术 用于处理气缸压力的系统和方法 (System and method for processing cylinder pressure ) 是由 克里斯多夫·波罗诺夫斯基 于 2020-03-24 设计创作，主要内容包括：本公开提供了“用于处理气缸压力的系统和方法”。公开了用于响应于经滤波的气缸压力数据而操作发动机的方法和系统。在一个示例中,可响应于经滤波的气缸压力数据来将燃料喷射正时提前,所述经滤波的气缸压力数据指示气缸中燃烧的起始从预期正时延迟。所述经滤波的气缸压力数据可经由数字滤波器生成。(The present disclosure provides "systems and methods for processing cylinder pressure". Methods and systems for operating an engine in response to filtered cylinder pressure data are disclosed. In one example, fuel injection timing may be advanced in response to filtered cylinder pressure data indicating that the start of combustion in the cylinder is retarded from an expected timing. The filtered cylinder pressure data may be generated via a digital filter.)

1. An engine operating method, comprising:

storing the values of the sampled cylinder pressure in a data array in a memory of the controller;

generating a first array of signal envelope data and a second array of signal envelope data from the values of the sampled cylinder pressure in the data array, the values in the first array of signal envelope data and the values in the second array of signal envelope data defining the values in the data array;

generating in the filtered array of cylinder pressure data values less than or equal to the values in the first array of signal envelope data and values equal to or greater than the values in the second array of signal envelope data; and

adjusting, via the controller, an engine actuator in response to the value in the filtered array of cylinder pressure data.

2. The engine method of claim 1, wherein the engine actuator is a fuel injector.

3. The engine method of claim 1, wherein the engine actuator is an exhaust gas recirculation valve.

4. The engine method of claim 1, wherein the engine actuator is a turbocharger waste gate.

5. The engine method of claim 1, wherein the engine actuator is a turbocharger vane control actuator.

6. The engine method of claim 1, wherein said values in said first array of signal envelope data are greater than said values in said second array of signal envelope data.

7. The engine method of claim 6, wherein said values in said first array of signal envelope data are based on one of said set of values of said sampled cylinder pressure being greater than all other of said set of values of said sampled cylinder pressure.

8. The engine method of claim 6, wherein said values in said second array of signal envelope data are based on one of said set of values of said sampled cylinder pressure being less than all other of said set of values of said sampled cylinder pressure.

9. An engine system, comprising:

an internal combustion engine including a cylinder with a pressure sensor; and

a controller comprising executable instructions stored in non-transitory memory to generate values in a filtered cylinder pressure data array based on stored cylinder pressure values and adjust an engine actuator in response to the values in the filtered cylinder pressure data array, the filtered cylinder pressure data array comprising values that are an average of values in a first signal envelope data array and values in a second signal envelope data array.

10. The engine system of claim 9, further comprising: a fuel injector; and further executable instructions stored in non-transitory memory to adjust fuel injector timing in response to values in the filtered cylinder pressure data.

11. The engine system of claim 9, further comprising: further executable instructions stored in a non-transitory memory to generate the first array of signal envelope data.

12. The engine system of claim 11, further comprising: further executable instructions stored in a non-transitory memory to generate the second array of signal envelope data.

13. The engine system of claim 9, further comprising: further executable instructions stored in a non-transitory memory to generate the values in the array of filtered cylinder pressure data from values in the first array of signal envelope data and values in the second array of signal envelope data.

Technical Field

The present disclosure relates generally to vehicle engines and more particularly to processing engine cylinder pressure data.

Background

The engine may include a plurality of cylinders to combust fuel and deliver propulsive power to the vehicle. The control system of the engine may attempt to operate the cylinders in a similar manner, but there may be differences in the manner in which combustion occurs in each cylinder due to variations in cylinder air charge, cylinder fueling, fuel injection timing, and cylinder temperature. One method for reducing the combustion difference between cylinders or determining whether combustion in a cylinder is proceeding as desired is to equip one or more engine cylinders with a gauge using a pressure sensor. Useful control parameters and combustion parameters may be determined based on cylinder pressure. However, the cylinder pressure sensor output may also include pressure artifacts, which may be related to the natural response of the cylinder in which the pressure sensor resides. These pressure artifacts may introduce errors into combustion parameters and control parameters that may be determined from cylinder pressure sensor outputs. One method for removing some of the undesirable resonant frequencies that may be generated in the cylinder pressure may be to filter the cylinder pressure data via an analog or digital low pass or band pass filter. However, while removing the natural resonant frequency of the cylinder, these filters may introduce phase delays, and they may also adversely alter the combustion process pressure. Thus, these filters may introduce errors into the control parameters and combustion parameters determined from cylinder pressure. For example, due to filtering techniques, the timing or onset of combustion may be retarded, the location and magnitude of peak cylinder pressure may be changed, and the crankshaft angle at which a particular level of cylinder charge mass is burned may be changed. Accordingly, it may be desirable to provide a method of filtering cylinder pressure data that preserves combustion pressure variations while removing resonant pressure variations that may be due to cylinder geometry.

Disclosure of Invention

The present inventors have recognized the above-mentioned shortcomings of conventional filters and have developed an engine operating method comprising: storing the values of the sampled cylinder pressure in a data array in a memory of the controller; generating a first array of signal envelope data and a second array of signal envelope data from the values of the sampled cylinder pressure in the data array, the values in the first array of signal envelope data and the values in the second array of signal envelope data defining the values in the data array; generating in the filtered array of cylinder pressure data values less than or equal to the values in the first array of signal envelope data and values equal to or greater than the values in the second array of signal envelope data; and adjusting, via the controller, an engine actuator in response to the value in the filtered array of cylinder pressure data.

By digitally filtering the cylinder pressure via a filter comprising an upper envelope and a lower envelope, it is possible to provide a technical effort to improve the determination of engine control parameters and combustion parameters such that the combustion in the engine cylinder can be improved and/or optimized. In particular, a left-side envelope acoustic filter (LEAF) algorithm may be applied to the sampled cylinder pressure data to remove acoustic resonance frequencies from the sampled cylinder pressure data that may be related to cylinder geometry and are not combustion pressure variations. By removing the acoustic frequency from the sampled cylinder pressure data, it is possible to generate a filtered cylinder pressure signal that may be more indicative of combustion in the engine cylinder and less indicative of the geometry of the engine. The left envelope acoustic filter exhibits a zero phase shift so that combustion event timing can be estimated without compensating for the phase delay that can accompany many analog filters.

The present description may provide several advantages. In particular, the method may improve pressure control of the engine cylinder. Additionally, the method may improve detection of combustion related artifacts in the cylinder pressure data. Further, the method is left-hand so that cylinder pressure changes due to combustion can be detected before the resonant frequency can be generated within the cylinder, thereby improving the process of distinguishing signals from acoustic noise in the cylinder pressure data.

The above advantages and other advantages and features of the present description will be readily apparent from the following detailed description when considered in connection with the accompanying drawings.

It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. This is not intended to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Additionally, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

Drawings

FIG. 1 shows a detailed schematic of an exemplary engine;

2-5C illustrate exemplary cylinder pressure traces and frequencies;

fig. 6 to 9 show the features of the left-side enveloped sound filter;

10-13 illustrate an exemplary method for filtering cylinder pressure and adjusting engine operation based on the filtered cylinder pressure.

Detailed Description

This description relates to operating an engine that includes a cylinder pressure sensor. FIG. 1 shows one example of a supercharged diesel engine including a cylinder pressure sensor. The engine may include a plurality of cylinders, each having a cylinder pressure sensor for determining a cylinder pressure in each of the cylinders. The pressure in the engine cylinder may include attributes as shown in fig. 2-5C. The cylinder pressure may be filtered via a left-side envelope acoustic filter operating as shown in fig. 6-9. The engine may be operated and cylinder pressures filtered via the methods shown in fig. 10-13.

Referring to FIG. 1, an internal combustion engine 10 is controlled by an electronic engine controller 12, the internal combustion engine 10 including a plurality of cylinders, one of which is shown in FIG. 1. The controller 12 receives signals from the various sensors of fig. 1. The controller 12 employs the various actuators of FIG. 1 to adjust engine operation based on the received signals and instructions stored on the controller's memory.

Engine 10 includes a combustion chamber 30 and a cylinder wall 32 with a piston 36 positioned therein and connected to a crankshaft 40. The cylinder head 13 is fastened to the engine block 14. Combustion chamber 30 is shown communicating with intake manifold 44 and exhaust manifold 48 via respective intake valve 52 and exhaust valve 54. Each intake and exhaust valve may be operated by an intake cam 51 and an exhaust cam 53. In other examples, however, the engine may operate the valves via a single camshaft or pushrod. The position of the intake cam 51 may be determined by an intake cam sensor 55. The position of exhaust cam 53 may be determined by exhaust cam sensor 57. The intake lift valves 52 may be operated by a variable valve activation/deactivation actuator 59, and the variable valve activation/deactivation actuator 59 may be a cam-driven valve operator (e.g., as shown in U.S. Pat. Nos. 9,605,603; 7,404,383 and 7,159,551, all of which are hereby fully incorporated by reference for all purposes). The exhaust lift gate 54 may include a rocker-detent device 58 to hold the exhaust valve open throughout the engine cycle. The rocker stop 58 may be referred to as a pressure relief valve actuator. The combination of exhaust valve 54 and rocker-stop device 58 may be referred to as a pressure relief valve. The flow of fuel supplied to the cylinders 30 may also be stopped when the rocker-stop device 58 holds the exhaust valves 54 open.

Fuel injector 68 is shown positioned in cylinder head 13 to inject fuel directly into combustion chamber 30, which is referred to by those skilled in the art as direct injection. Fuel is delivered to the fuel injectors 68 by a fuel system including a fuel tank 26, a fuel pump 21, a fuel pump control valve 25, and a fuel rail (not shown). The fuel pressure delivered by the fuel system may be adjusted by changing a position valve that regulates flow to a fuel pump (not shown). Additionally, a metering valve may be located in or near the fuel rail for closed loop fuel control. The pump metering valve may also regulate fuel flow to the fuel pump, thereby reducing fuel pumped to the high pressure fuel pump.

The engine intake system 9 includes an intake manifold 44, a throttle 62, a grille heater 16, a charge air cooler 163, a turbocharger compressor 162, and an intake plenum 42. Intake manifold 44 is shown communicating with an optional electronic throttle 62, where electronic throttle 62 adjusts a position of throttle plate 64 to control airflow from intake plenum 46. Compressor 162 draws air from intake plenum 42 to supply plenum 46. The compressor blade actuator 84 adjusts the position of the compressor blades 19. The exhaust gas rotates a turbine 164, the turbine 164 being coupled to a turbocharger compressor 162 via a shaft 161. In some examples, a charge air cooler 163 may be provided. In addition, an optional grill heater 16 may be provided to warm the air entering the cylinders 30 when the engine 10 is cold started. The compressor speed may be adjusted via adjusting the position of the turbine variable vane control actuator 78 or the compressor recirculation valve 158. In alternative examples, a wastegate 79 may replace the turbine variable vane control actuator 78, or a wastegate 79 may be used in addition to the turbine variable vane control actuator 78. The turbine variable vane control actuator 78 adjusts the position of the variable geometry turbine blades 166. When the vanes are in the open position, exhaust gas may pass through the turbine 164, supplying little energy to rotate the turbine 164. When the vanes are in the closed position, the exhaust gas may pass through the turbine 164 and exert an increased force on the turbine 164. Alternatively, a wastegate 79 or bypass valve may allow exhaust gas to flow around the turbine 164 in order to reduce the amount of energy supplied to the turbine. Compressor recirculation valve 158 allows compressed air at outlet 15 of compressor 162 to return to inlet 17 of compressor 162. Alternatively, the position of the compressor variable vane actuator 78 may be adjusted to vary the efficiency of the compressor 162. In this manner, the efficiency of the compressor 162 may be reduced to affect the flow of the compressor 162 and reduce the likelihood of compressor surge. Further, by returning air to the inlet of the compressor 162, the work performed on the air may be increased, thereby increasing the temperature of the air. An optional motor 165 is also shown coupled to the shaft 161. Air flows into the engine 10 in the direction of arrow 5.

Flywheel 97 and ring gear 99 are coupled to crankshaft 40. A starter 96 (e.g., a low voltage (operating at less than 30 volts) motor) includes a pinion shaft 98 and a pinion gear 95. Pinion shaft 98 may selectively advance pinion gear 95 to engage ring gear 99 such that starter 96 may rotate crankshaft 40 during an engine cranking event. The starter 96 may be mounted directly to the front of the engine or to the rear of the engine. In some examples, starter 96 may selectively supply torque to crankshaft 40 via a belt or a chain. In one example, starter 96 is in a base state when not engaged to the engine crankshaft. Engine start may be requested via a human/machine interface (e.g., key switch, button, remote radio frequency transmission device, etc.) 69 or in response to vehicle operating conditions (e.g., brake pedal position, accelerator pedal position, battery state of charge (SOC), etc.). The battery 8 may supply power to the starter 96. The controller 12 may monitor the battery state of charge.

When the fuel is automatically ignited via the combustion chamber temperature reaching the auto-ignition temperature of the fuel injected into the cylinder 30, combustion is induced in the combustion chamber 30. The temperature in the cylinder increases as piston 36 approaches a top-dead-center compression stroke. In some examples, a Universal Exhaust Gas Oxygen (UEGO) sensor 126 may be coupled to exhaust manifold 48 upstream of exhaust device 71. In other examples, the UEGO sensor may be located downstream of one or more exhaust aftertreatment devices. Further, in some examples, the UEGO sensor may be replaced with a NOx sensor having both a NOx sensing element and an oxygen sensing element.

At lower engine temperatures, optional glow plug 66 can convert electrical energy into thermal energy to create a hot spot next to one of the fuel spray cones of the injector in combustion chamber 30. By creating a hot spot next to the fuel spray in combustion chamber 30, the fuel spray plume in the cylinder may be more easily ignited, releasing heat that propagates throughout the cylinder, increasing the temperature in the combustion chamber, and improving combustion. Cylinder pressure may be measured via cylinder pressure sensor 67, alternatively or additionally, sensor 67 may also sense cylinder temperature.

In one example, the emissions device 71 may include an oxidation catalyst, and may be followed by a Diesel Particulate Filter (DPF)72 and a Selective Catalytic Reduction (SCR) catalyst 73. In another example, DPF 72 may be positioned downstream of SCR 73. The temperature sensor 70 provides an indication of the SCR temperature.

Exhaust Gas Recirculation (EGR) may be provided to the engine via a high pressure EGR system 83. The high-pressure EGR system 83 includes a valve 80, an EGR passage 81, and an EGR cooler 85. EGR valve 80 is a valve that blocks or allows exhaust gas to flow from upstream of exhaust 71 to a location in the engine intake system downstream of compressor 162. EGR may be cooled via passage through EGR cooler 85. EGR may also be provided via a low pressure EGR system 75. The low-pressure EGR system 75 includes an EGR passage 77 and an EGR valve 76. Low pressure EGR may flow from downstream of exhaust 71 to a location upstream of compressor 162. The low-pressure EGR system 75 may include an EGR cooler 74.

The controller 12 is shown in fig. 1 as a conventional microcomputer including: microprocessor unit 102, input/output ports 104, read only memory (e.g., non-transitory memory) 106, random access memory 108, keep alive memory 110, and a conventional data bus. Controller 12 is shown receiving various signals from sensors coupled to engine 10 in addition to those signals previously discussed, including: engine Coolant Temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114; a position sensor 134 coupled to the accelerator pedal 130 for sensing an accelerator position adjusted by the human foot 132; a measurement of engine manifold pressure (MAP) from a pressure sensor 121 coupled to intake manifold 44 (alternatively or additionally, sensor 121 may sense intake manifold temperature); boost pressure from pressure sensor 122; exhaust oxygen concentration from oxygen sensor 126; an engine position sensor from a Hall effect sensor 118 sensing crankshaft 40 position; a measurement of air mass entering the engine from a sensor 120 (e.g., a hot wire air flow meter); and a measurement of throttle position from sensor 58. Atmospheric pressure may also be sensed (sensor not shown) for processing by controller 12. In a preferred aspect of the present description, the engine position sensor 118 generates a predetermined number of equally spaced pulses per revolution of the crankshaft from which the engine speed (revolutions per minute (RPM)) can be determined.

During operation, each cylinder within engine 10 typically undergoes a four-stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. During the intake stroke, generally, exhaust valve 54 closes and intake valve 52 opens. Air is introduced into combustion chamber 30 via intake manifold 44 and piston 36 moves to the bottom of the cylinder to increase the volume within combustion chamber 30. The position at which piston 36 is near the bottom of the cylinder and at the end of its stroke (e.g., when combustion chamber 30 is at its largest volume) is typically referred to by those of skill in the art as Bottom Dead Center (BDC). During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head to compress air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g., when combustion chamber 30 is at its smallest volume) is commonly referred to by those skilled in the art as Top Dead Center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In some examples, fuel may be injected into a cylinder multiple times during a single cylinder cycle.

In a process hereinafter referred to as ignition, the injected fuel is ignited by compression ignition, resulting in combustion. During the expansion stroke, the expanding gases push piston 36 back to BDC. Crankshaft 40 converts piston movement into rotational torque of the rotary shaft. Finally, during the exhaust stroke, the exhaust valve 54 opens to release the combusted air-fuel mixture to exhaust manifold 48 and the piston returns to TDC. Note that the above is described merely as an example, and that intake and exhaust valve opening and/or closing timings may vary, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples. Further, in some examples, a two-stroke cycle may be used instead of a four-stroke cycle.

Accordingly, the system of fig. 1 provides an engine system comprising: an internal combustion engine including a cylinder with a pressure sensor; and a controller comprising executable instructions stored in non-transitory memory to generate values in a filtered cylinder pressure data array based on stored cylinder pressure values and adjust an engine actuator in response to the values in the filtered cylinder pressure data array, the filtered cylinder pressure data array comprising values that are an average of values in a first signal envelope data array and values in a second signal envelope data array. The engine system further includes: a fuel injector; and further executable instructions stored in non-transitory memory to adjust fuel injector timing in response to values in the filtered cylinder pressure data. The engine system further includes: further executable instructions stored in a non-transitory memory to generate the first array of signal envelope data. The engine system further includes: further executable instructions stored in a non-transitory memory to generate the second array of signal envelope data. The engine system further includes: further executable instructions stored in a non-transitory memory to generate the values in the array of filtered cylinder pressure data from values in the first array of signal envelope data and values in the second array of signal envelope data.

Referring now to FIG. 2, a graph of an example of a combustor resonant frequency is shown. The vertical axis represents signal amplitude in units of pressure increasing in the direction of the vertical axis arrow. The horizontal axis represents the frequency in the sampled cylinder pressure data, and the frequency increases in the direction of the horizontal axis arrow. In this example, the resonant frequency is indicated by a peak at each frequency in trace 202. The peak frequency occurs as indicated at 204.

Combustion in the engine cylinder releases chemical energy, which causes the cylinder pressure to rapidly rise or increase. The pressure from combustion may include frequency content that may overlap with the resonant natural frequencies and resonant modes of the cylinder and combustion chamber. The resonant natural frequency may be excited via an increase in cylinder pressure. In particular, the rising cylinder pressure due to combustion may excite resonant modes of the combustion chamber that appear in the measured cylinder pressure signal as sound waves or oscillatory waves that oscillate about the average combustion chamber cylinder pressure generated by combustion and lacking the resonant modes or frequencies. It may be desirable to filter out the resonant frequency so that the determination of the combustion and control parameters may be improved.

Referring now to FIG. 3, a graph is shown showing the frequency response of the original or unfiltered cylinder pressure 302 and the frequency response of the output of a Left Envelope Acoustic Filter (LEAF)304 operating on or filtering the original cylinder pressure. The vertical axis represents signal amplitude, and the signal amplitude increases in the direction of the vertical axis arrow. The horizontal axis represents the signal frequency, and the signal frequency increases from the left side of the graph to the right side of the graph. It can be observed that LEAF attenuates frequencies having peak amplitudes while maintaining most of the signal strength at frequencies where the amplitudes are fairly flat. For example, the LEAF output frequency response 304 indicates that the resonant frequency at frequency 306 is significantly attenuated. In contrast, typical low-pass analog filters and band-pass filters (not shown) typically attenuate all frequencies above their cutoff frequency and/or the filter cannot attenuate acoustic resonance frequencies that are in the pass-band of the filter. Thus, the values of the combustion parameters (e.g., start of combustion time or crank angle, location of peak cylinder pressure, location of mass fraction of 50% of combustion, and other combustion parameters) determined from the filtered cylinder pressures may not be as accurate as desired. However, LEAF generates a zero phase in its output, and it may damp resonant frequencies that may fall within a window of combustion pressure frequencies.

Referring now to FIG. 4A, a graph is shown showing a raw or unfiltered cylinder pressure signal and the output of a low pass filter applied to the raw cylinder pressure signal. The vertical axis represents cylinder pressure, and the cylinder pressure increases in the direction of the vertical axis. The horizontal axis represents engine position, and engine position advances from the left side of the figure to the right side of the figure. The raw cylinder pressure is indicated by the solid trace 402 and the low pass filtered cylinder pressure is indicated by the pressure dashed trace 404. When only trace 404 is visible, the low pass filtered cylinder pressure is equal to the original cylinder pressure. The low pass filtered cylinder pressure trace 404 is output from a 3kHz analog low pass filter that is filtering the raw cylinder pressure signal 402.

At the left side of the graph, the original cylinder pressure 402 equals the low pass filtered cylinder pressure 404 and rises, then it begins to fall and compression ignition occurs at an engine position coinciding with 406. After the original cylinder pressure begins to rise after ignition at 406, high frequency pressure oscillations begin to occur in the original cylinder pressure as the original cylinder pressure continues to rise and the engine position increases in the right direction. The low pass filtered cylinder pressure does not drop to a pressure as low as the original cylinder pressure and the low pass filtered cylinder pressure does not contain pressure oscillations that may be caused by the resonant cylinder frequency. Thus, the low pass filtered data lacks fidelity of the raw cylinder pressure data, which can lead to errors in determining some of the engine control parameters and combustion parameters determined from the cylinder pressure. Thus, low pass filtering of the raw cylinder pressure may attenuate undesirable cylinder resonant frequencies, but it may also distort or introduce errors into the determinations of the engine control parameters and combustion parameters. Thus, the low pass filter may not produce the desired result.

Referring now to FIG. 4B, a graph illustrating the output of the LEAF applied to the raw cylinder pressure signal shown in FIG. 4A is shown. The vertical axis represents cylinder pressure, and the cylinder pressure increases in the direction of the vertical axis. The horizontal axis represents engine position, and engine position advances from the left side of the figure to the right side of the figure. Trace 410 represents the LEAF output applied to the raw cylinder pressure 402 shown in FIG. 4A.

At the left side of the graph, the cylinder pressure 410 output from the LEAF follows the same trajectory as the original cylinder pressure, and then it begins to drop and compression ignition occurs at the engine location coinciding with 406. The cylinder pressure output from the LEAF follows the original pressure immediately before and after the firing position 406. When the raw cylinder pressure trace is oscillating as shown in fig. 4A, the cylinder pressure output from the LEAF after ignition at 406 follows the average of the raw cylinder pressure. Accordingly, the cylinder pressure output from the LEAF provides higher signal fidelity during an ignition event, such that more accurate ignition timing may be determined from the cylinder pressure output from the LEAF as compared to the cylinder pressure output from the low pass filter. In addition, LEAF attenuates the cylinder resonant frequency so that the cylinder resonant frequency may have less impact on the determination of the control parameters and cylinder pressure parameters.

Referring now to fig. 5A-5C, these figures show a cylinder pressure trace that does not include a cylinder resonant frequency (fig. 5A), a cylinder resonant frequency excited by rising cylinder pressure (fig. 5B), and a cylinder pressure trace that includes a cylinder resonant frequency (fig. 5C). These graphs are vertically aligned in terms of engine position.

The vertical axis of FIG. 5A represents cylinder pressure versus engine position, and cylinder pressure increases in the direction of the vertical axis arrow. The horizontal axis represents engine position, and engine position advances from the left side of the figure to the right side of the figure. Cylinder pressure 502 in fig. 5A represents pressure in a cylinder absent any resonant cylinder frequency mode. The cylinder pressure shown in fig. 5A is the cylinder pressure due to piston movement and combustion. Such cylinder pressures may be desired to be generated when determining or evaluating engine control parameters and cylinder combustion parameters. However, the cylinder pressure sensor may also be exposed to resonant cylinder pressures due to the natural frequency of the cylinder.

The cylinder pressure in fig. 5A begins with an increase on the left side of fig. 5A where the piston of the cylinder is approaching a top dead center compression stroke. Ignition of the air-fuel mixture in the cylinder occurs at 550. Since chemical energy is released from the air-fuel mixture in the form of heat, the cylinder pressure increases after ignition at 550.

FIG. 5B shows the generation of a cylinder resonant frequency of about 7 kHz. The vertical axis of fig. 5B represents cylinder pressure versus engine position, with cylinder pressure above the horizontal axis being positive and cylinder pressure below the horizontal axis being negative. The magnitude of the positive portion of the cylinder pressure signal 504 increases in the direction of the upward pointing vertical axis arrow in FIG. 5B. The magnitude of the negative portion of the resonant cylinder pressure signal 504 increases in the direction of the downward-pointing vertical axis arrow in FIG. 5B. The horizontal axis represents engine position, and engine position advances from the left side of the figure to the right side of the figure.

The cylinder pressure 504 in fig. 5B represents the resonant cylinder pressure, and the resonant cylinder pressure increases after combustion occurs at 550. The rising cylinder pressure excites a cylinder resonant mode, causing pressure oscillations in the cylinder. The amplitude of the pressure oscillations increases as the pressure in the cylinder increases. The cylinder pressure 504 shown in fig. 5B is the cylinder pressure due to the resonant cylinder mode. When determining or evaluating engine control parameters and cylinder combustion parameters, it may be desirable to attenuate such cylinder pressures so that engine control parameters and combustion parameters may be more accurately determined.

The vertical axis of FIG. 5C represents cylinder pressure versus engine position, and cylinder pressure increases in the direction of the vertical axis arrow. The horizontal axis represents engine position, and engine position advances from the left side of the figure to the right side of the figure. The cylinder pressure 506 in fig. 5C represents the pressure in the cylinder, and the pressure in the cylinder includes the pressure due to combustion and the pressure due to the cylinder resonance mode. This combined pressure is the pressure that can be observed via the pressure sensor in the cylinder. It may be desirable to remove or attenuate the cylinder resonance frequency so that the control parameters and the cylinder combustion parameters may be more accurately determined.

The cylinder pressure in fig. 5C begins with an increase on the left side of fig. 5C where the piston of the cylinder is approaching a top dead center compression stroke. Ignition of the air-fuel mixture in the cylinder occurs at 550. Since chemical energy is released from the air-fuel mixture in the form of heat, the cylinder pressure increases after ignition at 550. Further, the cylinder pressure starts oscillating due to the cylinder resonance mode.

Referring now to fig. 6-9, graphs showing the operation of the LEAF are shown. The LEAF may operate as described in FIGS. 6-9 to filter the cylinder pressure signal to remove undesired cylinder resonant frequencies from the cylinder pressure signal. LEAF introduces zero phase distortion and, because it is to the left, can generate a filtered pressure output with little effect on the resonant frequency that can be generated after combustion is initiated in the cylinder.

Referring now to fig. 6, a graph of a high envelope (e.g., data values in a first signal envelope data array) and a low envelope (e.g., data values in a second signal envelope data array) generated via LEAF during a filtering process is shown. LEAF begins by generating an upper signal envelope 604 and a lower signal envelope 606 that bound the raw cylinder pressure signal 602, as shown in FIG. 6. Thus, the cylinder pressure values in the raw cylinder pressure signal 602 are always less than or equal to the values in the upper envelope array holding the upper envelope values 604, and the cylinder pressure values in the raw cylinder pressure signal 602 are always greater than or equal to the values in the lower envelope array holding the values 606. Furthermore, the upper envelope value 604 is always larger than the lower envelope value 606. The lower envelope value 606 is generated by discretizing the raw cylinder pressure values towards local minima occurring within a time segment of the characteristic frequency. The characteristic frequency is the resonant frequency being attenuated. In the example where the resonant frequency is 7kHz, the time period is 1/7000 or 143 microseconds. Thus, for each cylinder pressure sample, the local minimum occurring within the 143 microsecond time window is recorded as the corresponding value of the lower envelope signal. The time window is bounded on the right by the index value and on the left by the number of values determining the width of the window. The same process is repeated to generate high envelope values 604, except that a local maximum is applied instead of a local minimum.

The LEAF then processes data from the raw cylinder pressures sampled during the predetermined crank angle region, starting with the earliest recorded cylinder pressure sample (e.g., the first cylinder pressure sample taken during the predetermined crank angle region). At each cylinder pressure sample point (e.g., an indexed cylinder pressure sample), LEAF collects a subset of the cylinder pressure sample points immediately preceding the indexed cylinder pressure sample point from the original cylinder pressure signal, the values in the lower envelope, and the values in the high envelope. The size or number of cylinder pressure sample points contained within the subset corresponds to a time period that is two or more times the characteristic time period. For example, in the case of a resonant frequency of 7kHz, the characteristic time period is 1/7000 or 143 microseconds, and the time period corresponding to the duration of the subset is 2 x 143 microseconds or 286 microseconds. Thus, all cylinder pressure sample points occurring 286 microseconds or less before the index sample are collected into the subset. In this example, this subset includes a total of 14 cylinder pressure sample points. The absolute minimum length of the subset may be twice the period of the characteristic frequency (e.g. 286 microseconds for 7 kHz). There is no maximum number of cylinder samples in the subset other than the total number of cylinder pressure samples in the original cylinder pressure sampled during the predetermined crank angle region, but increasing the number of cylinder samples in the subset to four or five times the characteristic time period may not provide any benefit. This is because the net improvement in LEAF is reduced to a negligible level after five times the characteristic time period.

An exemplary subset from the data shown in fig. 6 is shown in fig. 7. For the cylinder pressure subset shown in FIG. 7, X710 marks the index cylinder pressure sample, and circle 702 represents a subset of sample points. The LEAF compares the subset cylinder pressure sample points from the raw cylinder pressure to their corresponding subset sample points from the upper envelope 704 (e.g., the dashed line) and the lower envelope 706 (e.g., the dashed line). If all of the raw cylinder pressure subset samples match the values of the lower envelope 706, or if they match the upper envelope 704, the raw cylinder pressure sample values are retained as values in the output of the LEAF. In fig. 7, this is the case: all of the original signal subset cylinder pressure sample points 702 are matched to their corresponding sample points from the lower envelope 706. LEAF interprets this result as indicating: the index samples are not artifacts of the resonant frequency modes, but are merely characteristic of combustion pressure. Alternatively, if the previous condition is not satisfied and all of the raw cylinder pressure sample subset points do not match the lower envelope 706 or the upper envelope 704, then the LEAF designates the raw cylinder pressure index sample points as artifacts of the resonant frequency mode. The LEAF then records the filtered LEAF sample output of the index samples as the average of the data in the upper and lower envelopes using the same index cylinder pressure sample point from each index sample.

An example of this process is shown in FIG. 8, which shows the index cylinder pressure 850 and its corresponding subset of cylinder pressures indicated by circle 802. The upper envelope is indicated by the dash-dot line 804 and the lower envelope is indicated by the dashed line 806. Note that X (index sample) representing the LEAF filtered value is at an intermediate position between the upper envelope 804 and the lower envelope 806, which represents the average of the values in the upper envelope and the lower envelope at the same index value.

Fig. 8 shows that the raw cylinder pressure (indicated by circle 802) oscillates between an upper envelope 804 and a lower envelope 806, which is indicative of a resonant mode. The resonant mode represents cylinder pressure oscillations around the mean value. Thus, when the LEAF detects a cylinder pressure sample as an artifact of the resonant frequency mode, it replaces the cylinder pressure sample value with the average of the values in the upper and lower envelopes at the same index value, since this value represents the average pressure. LEAF performs this analysis throughout the entire length of the original cylinder pressure sampled during the predetermined crankshaft angle interval, and it replaces only the cylinder pressure samples identified as artifacts of the resonant mode frequency.

Referring now to FIG. 9, the output of the LEAF is shown along with the raw cylinder pressure that the LEAF receives as input. The vertical axis represents cylinder pressure, and the cylinder pressure increases in the direction of the vertical axis arrow. The horizontal axis represents engine position, and engine position advances in the direction of the horizontal axis arrow (e.g., moving from-15 to-5 crank degrees before the TDC compression stroke).

The raw cylinder pressure samples are indicated by solid line 902. The output of the LEAF is indicated by the dotted line 908. The upper cylinder pressure envelope is indicated by the dashed line 904. The lower cylinder pressure envelope is indicated by dashed line 906. When only the original cylinder pressure trace 902 is visible, the output of the LEAF and the upper and lower envelopes are equal to the original cylinder pressure.

The sequence starts from the left side of the graph and it moves to the right side of the graph. The original cylinder pressure rises on the left side of the graph and then it drops slightly before ignition is initiated at 950. The ignition increases the pressure in the cylinder, exciting a resonant mode of the cylinder, which causes the original cylinder pressure to begin oscillating to the right of 950. LEAF begins outputting the average of upper envelope value 904 and lower envelope value 906 shortly after 950. Therefore, the output of the LEAF approaches the cylinder pressure indicated in FIG. 5A. The output of the LEAF may then be analyzed to determine control parameters and cylinder combustion parameters for adjusting engine operation to improve engine performance and/or emissions.

Referring now to fig. 10-13, flow charts of methods for filtering cylinder pressure and operating an engine based on the filtered cylinder pressure are shown. The method of fig. 10-13 may be incorporated into and cooperate with the system of fig. 1-3. Furthermore, at least part of the methods of fig. 10-13 may be incorporated as executable instructions stored in a non-transitory memory, while other parts of the methods may be performed via a controller that transforms the operating states of devices and actuators in the physical world. The method of fig. 10-13 may be repeatedly performed for each engine cylinder including a cylinder pressure sensor.

At 1002, method 1000 operates an engine (e.g., rotates the engine and combusts air and fuel within the engine) and determines engine operating conditions. Engine operating conditions may include, but are not limited to, cylinder pressure, engine speed, engine load, engine temperature, barometric pressure, and ambient air temperature. Method 1000 proceeds to 1004.

At 1004, method 1000 judges whether or not engine combustion analysis and control is requested or required. Engine combustion analysis and control may be requested during engine start, engine operation, and engine stop. Engine combustion analysis may be requested via the controller in response to engine and vehicle operating conditions. If engine combustion analysis and control is requested or desired, the answer is yes and method 1000 proceeds to 1006. Otherwise, method 1000 proceeds to 1050.

At 1050, method 1000 operates the engine without performing combustion analysis and without combustion feedback (e.g., rotating the engine and combusting air and fuel within the engine cylinders). Method 1000 proceeds to exit.

At 1006, method 1000 samples cylinder pressure in the cylinder via controller 12. Sampling cylinder pressure may include sensing cylinder pressure via a pressure sensor and digitizing an output of the cylinder pressure sensor and storing discrete cylinder pressure values to a controller random access memory. The discrete cylinder pressure values stored in the controller memory may be referred to as raw or unfiltered cylinder pressures. The output of the cylinder pressure sensor may be sampled at a predetermined rate (sampling frequency fsampling) (e.g., 100 kHz). Method 1000 proceeds to 1008.

At 1008, method 1000 applies a windowing technique to classify sampled cylinder pressure data values stored in controller memory into cylinder combustion pressures and cylinder non-combustion pressures. For example, cylinder pressures sampled between a predetermined crank angle range (e.g., 140 crank degrees before and 180 crank degrees after the top dead center compression stroke of a cylinder cycle) may be classified as raw cylinder combustion pressures. Other cylinder pressures of the cylinder cycle sampled outside of the predetermined crank angle range may be classified as the original cylinder non-combustion pressure. The cylinder pressure sampled in the predetermined crank angle range may be referred to as raw cylinder combustion pressure signal data. Method 1000 proceeds to 1010 and 1055 after classifying the sampled cylinder pressure data values for the cylinder cycle.

At 1055, method 1000 applies a first low pass filter to the raw cylinder non-combustion pressure. The first low-pass filter may be a digital low-pass filter having a 7kHz cut-off frequency. The original cylinder non-combustion pressure is input to the first low-pass filter, and the output of the first low-pass filter is supplied to 1024. The output values of the first digital low pass filter may be stored in the controller random access memory in a first low pass filter output array.

At 1010, method 1000 applies a second low pass filter to the raw cylinder combustion pressure. The second low pass filter may be a digital low pass filter having a 2kHz cut-off frequency. The raw cylinder combustion pressure is input to the second low pass filter, and the output of the second low pass filter is supplied to 1012 and 1022. The output of the second low pass filter may be stored in a random access memory of the controller in a second array of low pass filter outputs. Method 1000 proceeds to 1012.

At 1012, method 1000 subtracts the output of the second low pass filter from the raw cylinder combustion pressure. This effectively high pass filters the raw cylinder combustion pressure to produce a high pass filtered cylinder combustion pressure that is stored to an array in controller random access memory. Method 1000 proceeds to 1014.

At 1014, method 1000 upsamples the high pass filtered cylinder combustion pressure. In one example, the high pass filtered cylinder combustion pressure is up sampled 20 times. The 20 upsampling converts the single high pass filtered cylinder combustion pressure sample into 20 high pass filtered cylinder combustion pressures having the same value as the single high pass filtered cylinder combustion pressure sample. In one example, the size of the array of high pass filtered cylinder combustion pressures increases by a factor of 20 when 20 upsamples are taken. Upsampling allows the LEAF to attenuate additional frequencies and improve the LEAF output. The upsampling frequency (uF samples) is the sampling frequency F samples multiplied by the upsampling rate (e.g., 20). The upsampled cylinder combustion pressures are stored in an array in controller random access memory. Method 1000 proceeds to 1016.

At 1016, method 1000 applies a third low pass filter to the upsampled cylinder combustion pressure stored in the upsampled cylinder combustion pressure array. The third low pass filter may be a digital low pass filter having a 50kHz cut-off frequency. The upsampled cylinder combustion pressure is input to a third low pass filter, and the output of the third low pass filter is supplied to 1018. The output values of the third low pass filter may be referred to as filtered upsampled cylinder combustion pressure, and these values may be stored in a filtered upsampled cylinder combustion pressure array. Method 1000 proceeds to 1018.

At 1018, method 1000 applies the LEAF described in fig. 11-13 to the values stored in the filtered array of upsampled cylinder combustion pressures. Method 1000 proceeds to 1020.

At 1020, method 1000 downsamples the values output from the LEAF. In one example, the LEAF output values are downsampled 20 times. Downsampling 20 times converts twenty LEAF output values into a single LEAF output value. In one example, downsampling is performed via determining an average of 20 LEAF output values and storing the average as one LEAF output cylinder value. The downsampled LEAF output values may be stored in the controller random access memory in a downsampled LEAF output array. Method 1000 proceeds to 1022.

At 1022, the method 1000 adds the output of the second low-pass filter at 1010 to the downsampled LEAF output. The values in the downsampled LEAF output array are added to the values in the second low-pass filter output array to generate a filtered combustion pressure array. The length of the filtered combustion pressure array and the length of the downsampled LEAF output array and the second low-pass filter output array are the same or equal. Thus, the values in the first row and the first column in the downsampled LEAF output array are added to the values in the first row and the first column in the second low-pass filter output array. The resulting values are stored as values in the first row and the first column of the filtered combustion pressure array. Method 1000 proceeds to 1024.

At 1024, method 1000 combines values in the first low pass filter output array with values in the filtered combustion pressure array to generate a cylinder pressure array for the entire cylinder cycle (e.g., two engine revolutions for a four-stroke engine). In particular, the cylinder pressure array for the entire cylinder cycle includes a non-combustion cylinder pressure and a combustion cylinder pressure. Method 1000 proceeds to 1026.

At 1026, method 1000 applies a fourth low pass filter to the values in the cylinder pressure array for the entire cylinder cycle. The fourth low pass filter may be a digital low pass filter having a cutoff frequency of 18 kHz. The values in the array of cylinder pressures for the entire cylinder cycle are input to a fourth low pass filter, and the output of the fourth low pass filter is supplied to 1024 as the values in the array of final filtered cylinder pressures.

At 1028, the values in the array of final filtered cylinder pressures are processed to determine engine control parameters and engine combustion parameters. For example, the method 1000 may determine a location of ignition for a cylinder cycle (e.g., a crankshaft angle at which ignition begins during the cylinder cycle), a location of peak cylinder pressure for the cylinder cycle, a crankshaft angle at which a predetermined mass fraction of the cylinder charge is burned, a rate of heat release in the cylinder, and other known engine control and combustion parameters. Method 1000 proceeds to 1030.

At 1030, method 1000 adjusts fuel injection timing, EGR amount supplied to the engine, spark timing of the spark-ignition engine, and cylinder air charge amount in response to the engine control parameters and combustion parameters determined at 1028. For example, if it is determined that ignition occurred 10 crankshaft degrees before the top dead center compression stroke and the requested or desired ignition timing was 12 crankshaft degrees before the top dead center compression stroke, method 1000 may advance the fuel injection timing via the fuel injector such that the ignition timing may be advanced. Further, if it is determined that the rate of heat release is greater than desired, additional EGR may be delivered to the engine via further opening of the EGR valve. In another example, if the peak cylinder pressure is greater than desired, the boost pressure may be reduced via turbocharger wastegate or vane control, lift gate timing adjustments, and/or fuel injection timing adjustments may be made to reduce the peak cylinder pressure. Method 1000 proceeds to exit.

Referring now to fig. 11, a method for applying LEAF is shown. At 1102, method 1100 initializes signal periods (e.g.E.g., variable period) for processing the filtered values in the array of upsampled cylinder combustion pressures via LEAF. In one example, the signal period is a period of a maximum frequency period of the upsampled cylinder combustion pressure. For example, if the cylinder pressure is up-sampled to 2000kHz, the signal period is determined to be 500 x 10 from 1/2000kHz^-9And s. Method 1100 begins by processing the highest frequency first so that the frequency requested to be attenuated (e.g., the acoustic cylinder resonance frequency) can be attenuated without attenuating other frequencies. Method 1100 proceeds to 1104.

At 1104, method 1100 determines a hysteresis envelope for the values in the filtered array of upsampled cylinder combustion pressures. The hysteresis envelope is determined as described in fig. 12. Method 1100 proceeds to 1106.

At 1106, method 1100 applies a transient acoustic discriminator to filter the values in the filtered array of cylinder combustion pressures. An acoustic discriminator is applied as described in fig. 13. Method 1100 proceeds to 1108.

At 1108, method 1100 judges whether or not the value of the period is equal to 1/Fmin, where Fmin is the lowest frequency to be attenuated in the filtered array of upsampled cylinder combustion pressures. For example, if the lowest acoustic noise to be attenuated is 7kHz, the method 1100 determines if the value of the period is equal to 143 microseconds. If the value of the period is equal to fmin, the answer is yes and method 1100 proceeds to return to the method of fig. 10. Otherwise, the answer is no, and method 1100 proceeds to 1120, at 1120, the value of the period is increased by 1/F sample or the inverse of the upsampling frequency (e.g., 1/(100kHz 20)). Method 1100 proceeds to 1104.

Referring now to FIG. 12, a method for generating data values forming an upper cylinder pressure envelope and data values forming a lower cylinder pressure envelope is shown. At 1202, method 1200 retrieves the output of a third low pass filter (e.g., a value in a filtered upsampled cylinder combustion pressure array, which may be designated as a signal), a value from the period of fig. 11 (e.g., a time interval of the frequency that is attenuated during an execution cycle), and a cylinder pressure upsampling frequency (uF sample) as described in fig. 10. Method 1200 proceeds to 1204.

At 1204, the method 1200 determines a value N, which is the actual total number of cylinder pressure samples in the time period (cycle). The value of N may be determined via the following equation: n ═ uF sample/(1/cycle). After determining the value of N, method 1200 proceeds to 1206.

At 1206, method 1200 initializes an index value for advancement by the filtered upsampled cylinder combustion pressure array (signal). The index is initialized to a value of 1. The method 1200 proceeds to 1208.

At 1208, method 1200 determines an array Y of the subset of filtered upsampled cylinder combustion pressures. In particular, the array Y is determined as Y ═ signal ((index-N +1): index), which copies the element index-N +1 bitindex into the array Y. For example, if the index is 30 and N is 10, then the data from cell or entry 21 of the signal array is copied over the data of cell or entry 30 to form array Y. Thus, array Y is established by removing a subset of values from the array of signals holding the filtered up-sampled cylinder combustion pressure data. Method 1200 proceeds to 1210.

At 1210, method 1200 generates a portion of a lower envelope defining filtered upsampled cylinder combustion pressure data by finding a minimum in the current subset of data Y. The portion of the lower envelope is generated via an instruction ENV low (index) that stores the minimum value in array Y in the array low envelope (ENV low) at the position index. As the value of the index is incremented, the fill array ENV is low. Method 1200 proceeds to 1212.

At 1212, method 1200 generates a portion of an upper envelope bounding the filtered upsampled cylinder combustion pressure data via finding a maximum in the current subset of data Y. The portion of the upper envelope is generated via an instruction ENV high (index) that stores the maximum value in array Y in the array high envelope (ENV high) at the location index, min (Y). As the value of the index is incremented, the fill array ENV is high. Method 1200 proceeds to 1214.

At 1214, method 1200 determines whether the current value of the variable index is less than the length of the signal array or the actual total number of elements stored in the signal array. If so, the answer is yes and method 1200 proceeds to 1250. Otherwise, the answer is no and method 1200 proceeds to 1216.

At 1250, the value of the variable index is incremented by 1. The method 1200 returns to 1208.

At 1216, method 1200 determines all local maxima and corresponding signal indices of array ENV high. The local maximum is the last index (index) within a specified time window where the pressure derivative (dP/dt) is positive and then becomes negative at index + 1. Therefore, depending on the size of the time window, there may be multiple maxima within the cylinder pressure signal, which may be referred to as local maxima. The method 1200 proceeds to 1218.

At 1218, method 1200 linearly interpolates all index values from 1: length (signal) (e.g., length of signal array or number of elements in signal array) using ENV max and ENV max indices (e.g., secondary index values) and stores as interpolated values in the ENV high of the array. Method 1200 proceeds to 1220.

At 1220, method 1200 determines all local maxima and corresponding signal indices for array ENV low. The local minimum is the last index (index) within a specified time window where the pressure derivative (dP/dt) is negative and then becomes positive at index + 1. Therefore, depending on the size of the time window, there may be multiple minima within the cylinder pressure signal, which may be referred to as local minima. Method 1200 proceeds to 1222.

At 1222, method 1200 linearly interpolates all index values from 1: length (signal) using ENV minimum and ENV minimum indices and stores as ENV high. For example, method 1200 proceeds to exit.

Referring now to FIG. 13, a method for filtering cylinder pressure data in a filtered up-sampled cylinder combustion pressure array (signal) is shown. At 1302, method 1300 retrieves the output of the third low pass filter (e.g., a value in a filtered up-sampled cylinder combustion pressure array, which may be designated as a signal), a value of N (e.g., the number of cylinder pressure samples in a cycle) from fig. 12, an empirically determined value NP defining a number of cycles, a lower cylinder pressure envelope EVN low, and an upper cylinder pressure envelope EVN high. Method 1300 proceeds to 1304.

At 1304, method 1300 initializes an index value for advancement by the filtered upsampled cylinder combustion pressure array (signal). The index is initialized to a value of 1. Method 1300 proceeds to 1206.

At 1306, method 1300 determines the values of three variables Y, H and L. The value of Y is the signal ((index- (N × NP) +1): index). Thus, Y is an array that starts at cell or entry index- (N × NP) +1 and ends at the cell or entry index. The values of array Y are replicated from the signal array or filtered up-sampled cylinder combustion pressure array.

The value of H is EVN high ((index- (N × NP) +1): index). Thus, H is an array that starts at cell or entry index- (N × NP) +1 and ends at the cell or entry index. The values of array H are replicated from the EVN high array or upper cylinder pressure envelope.

The value of L is ENV low ((index- (N × NP) +1): index). Thus, L is an array that starts at cell or entry index- (N × NP) +1 and ends at the cell or entry index. The value of array L is replicated from the ENV low array or lower cylinder pressure envelope. After determining the values in arrays Y, H and L, method 1300 proceeds to 1308.

At 1308, method 1300 determines whether the sum of the absolute values of (Y-H) is zero or whether the sum of the absolute values of (Y-L) is zero. If so, the answer is yes and method 1300 proceeds to 1310. Otherwise, the answer is no, and method 1300 proceeds to 1311. If (Y-H) is zero or if (Y-L) is zero, the cylinder pressure is based on or equal to a cylinder pressure value in the lower or upper cylinder pressure envelope, indicating that the cylinder pressure at the current index is combustion pressure only. Thus, combustion pressure will remain in the final filtered LEAF output. However, if (Y-H) is not zero and if (Y-L) is not zero, the cylinder pressure is not based on or not equal to the cylinder pressure value in the lower or upper cylinder pressure envelope, which indicates that the cylinder pressure at the current index is a sound pressure related to the natural frequency of the cylinder. Thus, the combustion pressure value will be replaced by the average of the value of the upper cylinder pressure envelope at the indexed position and the value of the lower cylinder pressure envelope at the indexed position. If (Y-H) is zero or if (Y-L) is zero, the answer is yes and method 1300 proceeds to 1310. Otherwise, method 1300 proceeds to 1311.

At 1310, method 1300 stores the current value in array Y at the indexed position reference in the LEAF output array F signal at the position reference position index. Method 1300 proceeds to 1312.

At 1312, method 1300 adds the value of array H at the position reference index to the value of array L at the position reference index, and then divides the result by two and stores the division result in the LEAF output array F signal at the position reference position index. Alternatively, method 1300 may store the percentage of the sum of the values from the H array plus the values from the L array (e.g., F signal ═ (H (index) + L (index)). 02) method 1300 proceeds to 1314.

At 1312, method 1300 determines whether the current value of the variable index is less than the length of the signal array or the actual total number of elements stored in the signal array. If so, the answer is yes and method 1300 proceeds to 1350. Otherwise, the answer is no, and method 1300 proceeds to exit.

At 1350, the value of the variable index is incremented by 1. Method 1300 returns to 1306.

In this manner, the method of fig. 10-13 generates an upper cylinder pressure envelope and a lower cylinder pressure envelope, and then generates a filtered cylinder pressure value that is an average of the upper cylinder pressure envelope and the lower cylinder pressure envelope of the filtered upsampled cylinder combustion pressure. The processes described in fig. 10-13 may remove undesirable acoustic pressures from the combustion pressure generated in the cylinder so that the determination of the combustion parameter and the engine control parameter may be improved. A variable "index" is a real number that may reference one or more of the arrays described herein.

Thus, the method of fig. 10-13 provides for an engine operating method comprising: storing the values of the sampled cylinder pressure in a data array in a memory of the controller; generating a first array of signal envelope data and a second array of signal envelope data from the values of the sampled cylinder pressure in the data array, the values in the first array of signal envelope data and the values in the second array of signal envelope data defining the values in the data array; generating in the filtered array of cylinder pressure data values less than or equal to the values in the first array of signal envelope data and values equal to or greater than the values in the second array of signal envelope data; and adjusting, via the controller, an engine actuator in response to the value in the filtered array of cylinder pressure data. The engine method includes: wherein the engine actuator is a fuel injector. The engine method includes: wherein the engine actuator is an exhaust gas recirculation valve. The engine method includes: wherein the engine actuator is a turbocharger waste gate. The engine method includes: wherein the engine actuator is a turbocharger vane control actuator. The engine method includes: wherein the values in the first array of signal envelope data are greater than the values in the second array of signal envelope data. The engine method includes: wherein the values in the first array of signal envelope data are based on one of the set of values of the sampled cylinder pressure being greater than all other values in the set of values of the sampled cylinder pressure. The engine method includes: wherein the values in the second array of signal envelope data are based on one of the set of values of the sampled cylinder pressure being less than all other of the set of values of the sampled cylinder pressure.

The method of fig. 10-13 provides for an engine operating method comprising: storing the values of the sampled cylinder pressure in a data array in a memory of the controller; generating values in a filtered cylinder pressure data array based on the stored values, the filtered cylinder pressure data array including values that are an average of values in a first signal envelope data array and values in a second signal envelope data array; and adjusting, via the controller, an engine actuator in response to the value in the filtered array of cylinder pressure data. The engine method includes: wherein the filtered array of cylinder pressure data further comprises a value that is not an average of the values in the first array of signal envelope data and the values in the second array of signal envelope data. The engine method further comprises: the stored value is filtered via a low pass filter. The engine method further comprises: upsampling an output of the low pass filter to generate an array of upsampled cylinder pressure data. The engine method further comprises: generating the first array of signal envelope data via selecting a maximum of a group of data in the array of upsampled cylinder pressure data. The engine method further comprises: generating the second array of signal envelope data via selecting a minimum of the set of data in the array of upsampled cylinder pressure data. The engine includes: wherein the engine actuator is an exhaust gas recirculation valve.

In another representation, the method of FIGS. 10-13 provides for an engine operating method comprising: storing the values of the sampled cylinder pressure in a data array in a memory of the controller; separating combustion cylinder pressure from non-combustion cylinder pressure from data in the data array, generating values in a filtered cylinder pressure data array based on the combustion cylinder pressure, the filtered cylinder pressure data array including values that are an average of values in a first signal envelope data array and values in a second signal envelope data array; and adjusting, via the controller, an engine actuator in response to the value in the filtered array of cylinder pressure data. The engine method includes: wherein the combustion cylinder pressure is identified via an engine crankshaft angle.

Note that the example control and estimation routines included herein may be used with various engine and/or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in a non-transitory memory and may be executed by a control system, including a controller, in conjunction with various sensors, actuators, and other engine hardware. Further, part of the method may be a physical action taken in the real world to change the state of the device. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various acts, operations, or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example examples described herein, but is provided for ease of illustration and description. One or more of the illustrated acts, operations, and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described acts, operations, and/or functions may graphically represent code to be programmed into the non-transitory memory of the computer readable storage medium in the engine control system, with the described acts being performed by executing instructions in the system including the various engine hardware components and the electronic controller. One or more of the method steps described herein may be omitted, if desired.

It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific examples are not to be considered in a limiting sense, because numerous variations are possible. For example, the above-described techniques may be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations and subcombinations regarded as novel and nonobvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.

According to the present invention, an engine operating method includes: storing the values of the sampled cylinder pressure in a data array in a memory of the controller; generating a first array of signal envelope data and a second array of signal envelope data from the values of the sampled cylinder pressure in the data array, the values in the first array of signal envelope data and the values in the second array of signal envelope data defining the values in the data array; generating in the filtered array of cylinder pressure data values less than or equal to the values in the first array of signal envelope data and values equal to or greater than the values in the second array of signal envelope data; and adjusting, via the controller, an engine actuator in response to the value in the filtered array of cylinder pressure data.

According to one embodiment, the engine actuator is a fuel injector.

According to one embodiment, the engine actuator is an exhaust gas recirculation valve.

According to one embodiment, the engine actuator is a turbocharger wastegate.

According to one embodiment, the engine actuator is a turbocharger vane control actuator.

According to one embodiment, the values in the first array of signal envelope data are larger than the values in the second array of signal envelope data.

According to one embodiment, said values in said first array of signal envelope data are based on one of said set of values of said sampled cylinder pressure being greater than all other values in said set of values of said sampled cylinder pressure.

According to one embodiment, said values in said second array of signal envelope data are based on one of said set of values of said sampled cylinder pressure being less than all other of said set of values of said sampled cylinder pressure.

According to the present invention, an engine operating method includes: storing the values of the sampled cylinder pressure in a data array in a memory of the controller; generating values in a filtered cylinder pressure data array based on the stored values, the filtered cylinder pressure data array including values that are an average of values in a first signal envelope data array and values in a second signal envelope data array; and adjusting, via the controller, an engine actuator in response to the value in the filtered array of cylinder pressure data.

According to one embodiment, the filtered array of cylinder pressure data further comprises values that are not an average of the values in the first array of signal envelope data and the values in the second array of signal envelope data.

According to one embodiment, the above invention is further characterized in that: the stored value is filtered via a low pass filter.

According to one embodiment, the above invention is further characterized in that: upsampling an output of the low pass filter to generate an array of upsampled cylinder pressure data.

According to one embodiment, the above invention is further characterized in that: generating the first array of signal envelope data via selecting a maximum of a group of data in the array of upsampled cylinder pressure data.

According to one embodiment, the above invention is further characterized in that: generating the second array of signal envelope data via selecting a minimum of the set of data in the array of upsampled cylinder pressure data.

According to one embodiment, the engine actuator is an exhaust gas recirculation valve.

According to the present invention, an engine system includes: an internal combustion engine including a cylinder with a pressure sensor; and a controller comprising executable instructions stored in non-transitory memory to generate values in a filtered cylinder pressure data array based on stored cylinder pressure values and adjust an engine actuator in response to the values in the filtered cylinder pressure data array, the filtered cylinder pressure data array comprising values that are an average of values in a first signal envelope data array and values in a second signal envelope data array.

According to one embodiment, the above invention is further characterized in that: a fuel injector; and further executable instructions stored in non-transitory memory to adjust fuel injector timing in response to values in the filtered cylinder pressure data.

According to one embodiment, the above invention is further characterized in that: further executable instructions stored in a non-transitory memory to generate the first array of signal envelope data.

According to one embodiment, the above invention is further characterized in that: further executable instructions stored in a non-transitory memory to generate the second array of signal envelope data.

According to one embodiment, the above invention is further characterized in that: further executable instructions stored in a non-transitory memory to generate the values in the array of filtered cylinder pressure data from values in the first array of signal envelope data and values in the second array of signal envelope data.