DIAGNOSTIC SYSTEM FOR A FUEL INJECTOR

Abstract

Diagnostic system for a fuel injector (121), comprising: a plurality of sensors (180) for acquiring vehicle data; a controller (110) including a fuel injector diagnostic module (190) configured to receive the vehicle data during operation of the vehicle and: a fuel injector (121) with a fixed armature (214); and / or selectively identify a fuel injector (121) with pintle fatigue; characterized in that the fuel injector diagnostic module (190) is configured to to identify the fuel injector (121) with the stuck armature (214) in response to increasing short-term fuel trim values and occurring cylinder misfires.

Description

INTRODUCTION

[0001] The present invention relates to internal combustion engines and in particular to a diagnostic system according to the preamble of claim 1 for a fuel injector, as is essentially known from US 2016 / 0 245 221 A1.

[0002] Further prior art can be found in the documents US 7 899 608 B1 and DE 10 2012 020 490 B3.

[0003] Air is drawn into an engine through an intake manifold. A throttle valve and / or engine valve timing control the airflow into the engine. The air mixes with fuel from one or more fuel injectors to form an air / fuel mixture. The air / fuel mixture is combusted in one or more of the engine's cylinders. Combustion of the air / fuel mixture can be initiated, for example, by a spark generated by a spark plug.

[0004] The combustion of the air / fuel mixture produces torque and exhaust gas. Torque is generated via heat release and expansion during the combustion of the air / fuel mixture. The engine transfers torque to a transmission via a crankshaft, and the transmission transfers torque to one or more wheels via a driveline. Exhaust gas is expelled from the cylinders to an exhaust system.

[0005] Improper fuel injector operation can lead to one or more problems. For example, improper fuel injector operation can cause rough idle or engine misfiring or stalling. If the faulty fuel injector remains undiagnosed or identified, the engine may develop additional problems.

[0006] The invention is therefore based on the object of providing a diagnostic system with which faulty fuel injection nozzles can be reliably detected. SUMMARY

[0007] This object is achieved by a diagnostic system for a fuel injection nozzle, which is characterized by the features of claim 1.

[0008] Advantageous further developments of the invention are specified in the subclaims.

[0009] In other features, the fuel injector diagnostic module is configured to identify the fuel injector with the stuck armature based on short-term fuel trim values.

[0010] In other features, the fuel injector diagnostic module is configured to identify the fuel injector with the stuck armature during an engine cold start. The fuel injector diagnostic module is configured to identify the fuel injector with the stuck armature when the short-term fuel trim value is not nominal during an engine cold start.

[0011] In other features, the fuel injector diagnostic module is configured to identify the fuel injector with the stuck armature when a fuel rail pressure is greater than a predetermined fuel rail pressure. The fuel injector diagnostic module is configured to identify the fuel injector with pintle fatigue based on a fast Fourier transform (FFT) of cylinder misfires as a function of a plurality of groups of consecutive engine revolutions in a window. The fuel injector diagnostic module is configured to identify the fuel injector with pintle fatigue in response to the FFT having a greater amplitude than a predetermined amplitude at a greater frequency than a predetermined frequency in the window.

[0012] In other features, the fuel injector diagnostic module is configured to identify the fuel injector with pintle fatigue based on a fast Fourier transform (FFT) of cylinder misfires as a function of a plurality of groups of consecutive engine revolutions in a plurality of windows.

[0013] In other features, the fuel injector diagnostic module is configured to identify the fuel injector having pintle fatigue in response to X or more of Y consecutive windows of the plurality of windows having a greater amplitude than a predetermined amplitude at a greater frequency than a predetermined frequency, where X and Y are integers and X is less than Y.

[0014] In other features, the fuel injector diagnostic module is configured to further identify the fuel injector with the stuck armature in response to the long-term fuel trim values changing by more than a predetermined amount during a period of time less than a predetermined period of time.

[0015] A fuel injector diagnostic system includes a plurality of sensors to collect vehicle data. A fuel injector diagnostic module is configured to receive the vehicle data during vehicle operation and selectively identify a fuel injector with pintle fatigue based on a fast Fourier transform (FFT) of cylinder misfires as a function of a plurality of groups of consecutive engine revolutions within a window.

[0016] In other features, the fuel injector diagnostic module is further configured to identify a fuel injector with the stuck armature based on short-term fuel trim values. The fuel injector diagnostic module is configured to identify the fuel injector with the stuck armature during an engine cold start in response to increasing short-term fuel trim values and occurring cylinder misfires.

[0017] In other features, the fuel injector diagnostic module is configured to identify the fuel injector with pintle fatigue in response to the FFT having a greater amplitude than a predetermined amplitude at a greater frequency than a predetermined frequency in a plurality of windows. The fuel injector diagnostic module is configured to identify the fuel injector with pintle fatigue in response to X or more of Y consecutive windows of the plurality of windows having a greater amplitude than the predetermined amplitude at a greater frequency than the predetermined frequency, where X and Y are integers and X is less than Y.

[0018] In other features, the fuel injector diagnostic module is configured to further identify the fuel injector with the stuck armature in response to the long-term fuel trim values changing by more than a predetermined amount during a period of time less than a predetermined period of time.

[0019] A diagnostic system for fuel injectors of a plurality of vehicles includes a server remotely located from the plurality of vehicles and configured to receive vehicle data generated by the plurality of vehicles during operation. The server includes a fuel injector diagnostic module configured to receive the vehicle data from the plurality of vehicles and selectively identify one of the plurality of vehicles having a fuel injector with a stuck armature and / or one of the plurality of vehicles having a fuel injector with pintle fatigue.

[0020] In other features, the fuel injector diagnostic module is configured to identify the fuel injector with the stuck armature in response to increasing short-term fuel trim values during an engine cold start and to cylinder misfires occurring during the engine cold start. The fuel injector diagnostic module is configured to identify the fuel injector with pintle fatigue based on a fast Fourier transform (FFT) of cylinder misfires as a function of a plurality of groups of consecutive engine revolutions within a window.

[0021] Further areas of applicability of the present invention will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are provided for illustrative purposes only. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will become more fully understood from the detailed description and the accompanying drawings, in which: Fig. 1A is a functional block diagram of an example of an engine control system according to the present invention; Fig. 1B is a functional block diagram of an example of an engine control system according to the present invention; Fig. 2A and Fig. 2B are side cross-sectional views of an example of a fuel injector according to the present invention; Fig. 3 is an example of a fuel injector timing diagram for a single combustion event according to the present invention; Fig. Figure 4 is an example of short-term fuel trim values as a function of time according to the present invention; Fig. 5 is an example of misfire counts as a function of time according to the present invention; Fig. 6 is a flowchart of an example of a method for diagnosing a stuck armature in a fuel injector according to the present invention; Fig. 7 and Fig. 8 are examples of misfire counts as a function of engine speeds according to the present invention; Fig. 9 and Fig. 10 Examples of FFT sizes according to the present disclosure are; Fig. 11A to 11D are examples of fuel trim LTM as a function of engine speed according to the present invention; and Fig. 12 is a flowchart of an example of a method for diagnosing pintle fatigue in a fuel injector according to the present invention.

[0023] Reference numbers may be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0024] An engine burns a mixture of air and fuel in cylinders to produce driving torque. A throttle valve regulates the airflow into the engine. Fuel is injected via fuel injectors. Spark plugs can create sparks in the cylinders to initiate combustion. Some engine types, such as diesel engines, do not require spark plugs. A cylinder's intake and exhaust valves can be controlled to regulate the flow into and out of the cylinder.

[0025] The fuel injectors receive fuel from a fuel rail. In some examples, a high-pressure fuel pump receives fuel from a low-pressure fuel pump and pressurizes the fuel within the fuel rail. The low-pressure fuel pump draws fuel from a fuel tank and provides fuel to the high-pressure fuel pump. The fuel injectors inject fuel directly into the engine's cylinders. Power is supplied to a fuel injector to open the fuel injector (e.g., its pintle or armature).

[0026] One or more of the fuel injectors may have manufacturing issues. Examples of manufacturing issues include pintle fatigue and / or a stuck armature. Improper heat treatment of the pintle can cause the pintle to fatigue and fail sooner than expected. Reduced armature clearance can lead to uneven armature movement. If these types of manufacturing issues are not identified early, the fuel injectors can cause additional damage, increasing warranty costs.

[0027] Systems and methods according to the present invention perform identification of fuel injectors with manufacturing issues. Specifically, the systems and methods monitor control and diagnostic signals to identify fuel injectors with manufacturing issues to enable earlier repair before further damage occurs.

[0028] With reference to Fig. 1A, a functional block diagram of an exemplary engine system 100 is presented. The engine system 100 includes an engine 102 that combusts an air / fuel mixture to produce propulsion torque for a vehicle. While the engine 102 is discussed as a spark-ignition direct injection (SIDI) engine, the engine 102 may include another type of direct injection engine. In some examples, one or more electric motors and / or motor-generator units (MGUs) (not shown) may be provided in addition to the engine 102.

[0029] Air is drawn into an intake manifold 106 through a throttle valve 108. The throttle valve 108 may vary airflow into the intake manifold 106. For example only, the throttle valve 108 may include a butterfly valve with a rotatable vane. An engine control module (ECM) 110 controls a throttle valve actuator module 112 (e.g., an electronic throttle controller or ETC), and the throttle valve actuator module 112 controls opening of the throttle valve 108.

[0030] Air from intake manifold 106 is drawn into cylinders of engine 102. While engine 102 may include more than one cylinder, only a single representative cylinder 114 is shown. Air from intake manifold 106 is drawn into cylinder 114 via an intake valve 118. Each cylinder may have one or more intake valves.

[0031] The ECM 110 controls fuel injection (e.g., amount and timing) into cylinder 114 via a fuel injector 121. The fuel injector 121 injects fuel, such as gasoline or diesel, directly into the cylinder 114. In some examples, the fuel injector 121 is a solenoid-type direct injection fuel injector. The ECM 110 can control fuel injection to achieve a desired air / fuel ratio, such as a stoichiometric air / fuel ratio. One fuel injector is provided for each cylinder.

[0032] The injected fuel mixes with air, creating an air / fuel mixture in cylinder 114. Based on a signal from the ECM 110, a spark actuator module 122 may energize a spark plug 124 in cylinder 114. A spark plug may be provided for each cylinder. The spark generated by the spark plug 124 ignites the air / fuel mixture. Some engine types, such as diesel engines, may not require spark plugs.

[0033] The engine 102 may operate utilizing a four-stroke cycle or other suitable operating cycle. The four strokes described below may be referred to as the intake stroke, the compression stroke, the combustion stroke, and the exhaust stroke. During each revolution of a crankshaft (not shown), two of the four strokes occur within cylinder 114. Therefore, two revolutions of the crankshaft are required for the cylinders to experience all four strokes.

[0034] During the intake stroke, air is drawn from intake manifold 106 through intake valve 118 into cylinder 114. Fuel injected by fuel injector 121 mixes with air to create an air / fuel mixture in cylinder 114. One or more fuel injections may occur during a combustion cycle. During the compression stroke, a piston (not shown) in cylinder 114 compresses the air / fuel mixture. During the combustion stroke, the combustion of the air / fuel mixture drives the piston, thereby rotating the crankshaft. During the exhaust stroke, the byproducts of combustion are expelled via an exhaust valve 126 to an exhaust system 127.

[0035] A low-pressure fuel pump 142 draws fuel from a fuel tank 146 and delivers fuel at low pressures to a high-pressure fuel pump 150. Although only fuel tank 146 is illustrated, more than one fuel tank 146 may be used. The high-pressure fuel pump 150 further pressurizes the fuel in a fuel rail 154. The fuel injectors of the engine 102, including fuel injector 121, receive the fuel via the fuel rail 154. Low pressures provided by the low-pressure fuel pump 142 are described relative to high pressures provided by the high-pressure fuel pump 150.

[0036] The low-pressure fuel pump 142 may be an electrically driven pump. The high-pressure fuel pump 150 may be a variable-discharge pump mechanically driven by the engine 102. A pump actuator module 158 may control the operation (e.g., discharge) of the high-pressure fuel pump 150. The pump actuator module 158 controls the high-pressure fuel pump 150 based on signals from the ECM 110. The pump actuator module 158 may also control the operation (e.g., ON / OFF state) of the low-pressure fuel pump 142.

[0037] The engine system 100 may include one or more sensors 180. The sensors 180 may include, for example, one or more fuel pressure sensors, a mass air flow (MAF) sensor, a manifold absolute pressure (MAP) sensor, an intake air temperature (IAT) sensor, a coolant temperature sensor, an oil temperature sensor, a crankshaft position sensor, one or more wheel speed sensors, a fuel rail pressure sensor, and / or one or more other suitable sensors.

[0038] The ECM 110 includes a fuel injector diagnostic module 190 that performs one or more diagnostics to identify manufacturing issues with one or more fuel injectors. The fuel injector diagnostic module 190 includes an armature diagnostic module 192 configured to diagnose manufacturing issues related to a stuck armature. The fuel injector diagnostic module 190 includes a pintle diagnostic module 194 configured to diagnose manufacturing issues related to pintle fatigue.

[0039] Now on Fig. Referring to Figure 1B, the ECMs 110 of a plurality of vehicles may transmit the vehicle data for remote processing rather than processing the collected data locally. For example, the plurality of vehicles may include wireless transceivers 195 that transmit and receive data to and from cellular or satellite transceivers 196 that are directly or indirectly connected to a distributed communications system 197, such as the Internet. A remote server 198 is directly or indirectly connected to the distributed communications system 197 and includes the fuel injector diagnostic module 190 that performs one or more diagnostics based on vehicle data sent from the plurality of vehicles to identify manufacturing issues with one or more fuel injectors of a plurality of vehicles.The fuel injector diagnostic module 190 includes the armature diagnostic module 192 and / or the pintle diagnostic module 194 described above. If an injector problem is diagnosed, the remote server 198 generates and transmits a diagnostic message to corresponding vehicles of the plurality of vehicles that submitted the vehicle data with an injector problem. In some examples, the diagnostic message generates a visual or audible indication that the fuel injectors or the vehicle require service.

[0040] With reference to Fig. 2A and Fig. 2B, an example of a fuel injector 200 is shown. The fuel injector 200 includes a body 210 housing an armature 214 disposed radially within a guide sleeve 216. When energized, the armature 214 selectively moves a pintle 222 upward against one or more springs 230, temporarily relieving pressure on a pintle ball 234 against an inner surface of a nozzle body 236 defining a nozzle 238. When the pressure on the pintle ball is relieved, fuel flows through the nozzle 238. In the de-energized state, the armature 214 exerts no force against the springs 230, and the pintle 222 forces the pintle ball 234 against the inner surface of the nozzle body 236, blocking the nozzle 238.

[0041] One or more of the fuel injectors may be causing improper operation due to manufacturing issues. Examples of manufacturing issues include pintle fatigue and / or a stuck armature. For example, improper heat treatment of the pintle can cause the pintle to fatigue and fail sooner than expected. Reduced armature clearance can lead to uneven armature movement. If these types of manufacturing issues are not identified early, the fuel injectors can cause additional damage and increase warranty costs.

[0042] With reference to Fig. 3, Fig. 4 and Fig. 5 shows faulty and nominal operation of the fuel injectors. In Fig. Figure 3 shows a timing diagram of the fuel injectors for a single combustion event. Fig. 4 shows the short-term fuel trim to compensate for faulty operation. In Fig. Figure 5 shows the misfire count for each cylinder. Systems and methods according to the present invention extract features from control and diagnostic signals to detect failure modes related to manufacturing problems early.

[0043] During cold start operation, Fig. 3 in an upper part the injection nozzle openings with nominal pulses and in Fig. 3 shows the injector openings with faulty pulses in the lower part. As can be seen, a reduced clearance between the armature and the guide sleeve requires a greater force and consequently increases the response time of the injector. Less fuel is delivered, and idling becomes rougher. This problem can be compensated for by opening the fuel injector for a longer period (short-term fuel trim as in Fig. 4). If less fuel is delivered, this condition can also cause cylinder misfires (as shown in Fig. 5 is shown).

[0044] With reference to Fig. 6 illustrates a method 300 for detecting fuel injectors with manufacturing issues. At 320, a cold start threshold temperature is retrieved. At 324, a determination is made based on the cold start temperature and the engine temperature whether the engine is currently undergoing a cold start. In some examples, the engine temperature is used as the engine temperature and compared to the cold start threshold temperature to determine whether the engine start is a cold start or not.

[0045] If 324 is false, the method returns to 320. If 324 is true, the method continues to 328 and queries short-term fuel trim values. At 332, the method determines if the short-term fuel trim value is nominal for a cold start. If 332 is true, the method returns to 320. If 332 is false, the method continues to 334 and determines if the fuel rail pressure is in a low fault condition. If 334 is true, the method continues to 338 and sets a diagnostic flag related to suspected fuel pressure problems (and does not set a diagnostic flag related to the fuel injectors).

[0046] If 334 is false, the method continues at 340 and determines whether an intake air system is healthy based on intake air system health parameters. An example of systems and methods for determining whether the air system is healthy can be found in commonly assigned U.S. Patent No. 10,026,241 B1 and U.S. Patent No. 10,152,834 B1. If 340 is false and the intake air system is not healthy, the method diagnoses a suspected air delivery problem and sets a diagnostic flag (and not a fuel injector diagnostic flag).

[0047] If 340 is true and the intake air system is healthy, the method determines whether the short-term fuel trim is increasing at 348. In some examples, the slope and / or magnitude of the short-term fuel trim is compared to a predetermined slope and / or magnitude, respectively. For example, the short-term fuel trim is considered to be increasing if the slope is greater than a predetermined slope (such as 0.4, 0.5, 0.6, 0.7, and / or another value) and / or if the magnitude of the short-term fuel trim is greater than a predetermined magnitude (such as 110% or 120% of a nominal short-term fuel trim value) (although other thresholds may be used). If the slope and / or value exceeds the predetermined slope and / or value, then in some examples, the short-term fuel trim value is considered to be increasing.

[0048] If 348 is false (the short-term fuel trim is decreasing or not increasing sufficiently), the method determines at 352 that another fuel injector fault is suspected. If 348 is true (the short-term fuel trim is increasing sufficiently), the method continues at 360 and determines if a misfire is detected at a cylinder. In some examples, a single misfire is sufficient, although a higher number of misfires may be used. If 360 is true, the method continues at 364 and identifies the fuel injector with a stuck armature. If 360 is false, the method continues at 368 and queries whether the engine has multiple cylinder banks. If 368 is true, the method generates a message identifying the bank with the stuck armature at 374. If 368 is false, the method generates a message that the engine has a stuck armature at 372.

[0049] With reference to Fig. 7 to 10, cylinder-specific misfire patterns are used to identify fuel injector failure due to pintle fatigue. In Fig. 7 and Fig. 8, misfire counts are collected as a function of total engine speed. In some examples, misfire counts are collected, grouped, or classified for consecutive engine revolutions. In some examples, misfire counts are collected for each class or group including B engine revolutions, where B is an integer greater than 100. For example, B may be set to 100, 200, 500, 1000, 2000, or another number of engine revolutions.

[0050] A moving window fast Fourier transform (FFT) can be used to detect the presence of higher frequency signals with large magnitudes. Each of the engine revolution bins corresponds to a unit of time. The moving window comprises M bins, where M is an integer greater than 1. In some examples, B = 25, 50, 75, or 100, although higher or lower numbers can be used. The FFT is performed on the moving window. Then, the moving window is incremented by one bin, and the FFT is repeated.

[0051] In Fig. 9 and Fig. Figure 10 shows examples of magnitude and frequency thresholds for FFTs with two moving windows. The amplitude and frequency thresholds can be adjusted for a specific engine and / or vehicle.

[0052] Now on Fig. Referring to Figures 11A to 11D, sudden changes in long-term fuel trim are shown as a function of engine revolutions. Relatively sudden changes in long-term fuel trim are at 400 in Fig. 11A and Fig. 11B and at 410 in Fig. 11C and Fig. 11D.

[0053] With reference to Fig. 12, a method 500 for diagnosing a fuel injector with a manufacturing problem is shown. At 510, engine revolution data is collected. At 514, the method determines whether any of the cylinders are misfiring. If 514 is false, the method returns to 510. If 514 is true, the method continues at 518 and performs a moving window fast Fourier transform (FFT). At 522, the method determines whether signal frequencies above a predetermined frequency with amplitudes greater than a predetermined amplitude are present. For example, only Fig. 9 and Fig. 10 show examples of predetermined frequencies and / or amplitudes.

[0054] If 522 is false, the method continues to 532 (whereby diagnosing issues other than fuel injector manufacturing issues). If 522 is true, the method continues to 534 and determines if there is a change in long-term fuel trim. In some examples, if the slope and / or magnitude increases and / or decreases sufficiently, the long-term fuel trim is considered to be changing.

[0055] For example, the long-term fuel trim is considered to be changing if the slope of the long-term fuel trim is greater than a predetermined positive slope of (and / or less than a predetermined negative slope) the long-term fuel trim and / or if its magnitude is greater than a first predetermined magnitude (and / or less than a second predetermined magnitude), although other thresholds may be used. For example, the predetermined positive slope may be equal to 0.4, 0.5, 0.6, 0.7, and / or another value. For example, the predetermined negative slope may be equal to -0.4, -0.5, -0.6, -0.7, and / or another value.

[0056] The first predetermined long-term fuel trim value may be set to 110% or 120% of a nominal long-term fuel trim value. The second predetermined long-term fuel trim value may be set to 80% or 90% of a nominal long-term fuel trim value.

[0057] If 534 is true, the method continues at 538 and determines whether the change has been observed for a period of time shorter than a predetermined period. If either 534 or 538 is false, a problem other than manufacturing issues with the fuel injectors is diagnosed at 540.

[0058] If 538 is true, the method continues at 544 and determines whether higher frequencies with large amplitudes are observed in X of Y previous moving windows, where X and Y are integers and X ≤ Y. By way of example only, X = 4 and Y = 7, although other values may be used.

[0059] If 544 is true, the fuel injector is flagged at 548 indicating that it has pintle fatigue. If 544 is false, then a problem other than manufacturing issues with the fuel injectors is diagnosed.

[0060] The systems and methods described here can be used to detect fuel injectors with pintle fatigue and / or stuck armature. Early detection of these types of manufacturing problems allows the fuel injectors to be replaced before they cause additional damage and increased warranty costs.

Claims

[1] Diagnostic system for a fuel injector (121), comprising: a plurality of sensors (180) for acquiring vehicle data; a controller (110) including a fuel injector diagnostic module (190) configured to receive the vehicle data during operation of the vehicle and: a fuel injector (121) with a fixed armature (214); and / or selectively identify a fuel injector (121) with pintle fatigue; characterized by , that the fuel injector diagnostic module (190) is configured to to identify the fuel injector (121) with the stuck armature (214) in response to increasing short-term fuel trim values and occurring cylinder misfires. [2] The diagnostic system of claim 1, wherein the fuel injector diagnostic module (190) is configured to identify the fuel injector (121) having the stuck armature (214) during a cold start of the engine (102). [3] The diagnostic system of claim 1, wherein the fuel injector diagnostic module (190) is configured to identify the fuel injector (121) having the stuck armature (214) when a short-term fuel trim value is not nominal during engine cold start. [4] The diagnostic system of claim 1, wherein the fuel injector diagnostic module (190) is configured to identify the fuel injector (121) having the stuck armature (214) when a fuel rail pressure is greater than a predetermined fuel rail pressure. [5] The diagnostic system of claim 1, wherein the fuel injector diagnostic module (190) is configured to identify the fuel injector (121) with pintle fatigue based on a fast Fourier transform (FFT) of cylinder misfires as a function of a plurality of groups of consecutive engine revolutions in a window. [6] The diagnostic system of claim 5, wherein the fuel injector diagnostic module (190) is configured to identify the fuel injector (121) having pintle fatigue in response to the FFT having a greater amplitude than a predetermined amplitude at a greater frequency than a predetermined frequency in the window. [7] The diagnostic system of claim 1, wherein the fuel injector diagnostic module (190) is configured to identify the fuel injector (121) with pintle fatigue based on a fast Fourier transform (FFT) of cylinder misfires as a function of a plurality of groups of consecutive engine revolutions in a plurality of windows. [8] The diagnostic system of claim 7, wherein the fuel injector diagnostic module (190) is configured to identify the fuel injector (121) having pintle fatigue in response to X or more of Y consecutive windows of the plurality of windows having a greater amplitude than a predetermined amplitude at a greater frequency than a predetermined frequency, where X and Y are integers and X is less than Y.

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