JP2005127258A - Misfire detecting device for gaseous fuel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To assist to detect a misfire, and identify its cause. <P>SOLUTION: In a case where a misfire is determined based on a first detection value by first misfire determination at the time of normal driving (S20), driving force of an injector is increased (S40), and if the misfire exists or not is determined based on a second detection value as the driving force is increased in second misfire determination (S70). In a case where the state of the misfire is eliminated as the driving force is increased, the cause of the misfire in the first misfire determination can be highly possibly determined as fixture of the injector. Specification of the cause of the misfire by an inspection worker can thus be favorably assisted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine using gas fuel, and more particularly to an apparatus that performs misfire detection.

  In recent years, various gas fuel engines have been proposed to use gas fuels such as CNG (Compressed Natural Gas), hydrogen, and LPG (Liquid Petrol Gas) as fuel for internal combustion engines for automobiles. ing. In a gas fuel engine, if oil such as lubricating oil mixed in the fuel or heavy components in the fuel adheres to the seal or sliding part of the injector from the compressor that fills the fuel, the injector sticks and the injection In many cases, the characteristics change, and the combustion state fluctuates and misfires occur. This phenomenon is often observed at low temperatures such as during warm-up.

  Various means have been proposed as means for detecting misfire of a gas fuel engine. For example, Patent Document 1 discloses a technique for detecting misfire by comparing an exhaust pressure waveform of an engine with a reference waveform. Patent Document 2 discloses a technique for detecting misfire by comparing the throttle opening estimated from the output of the gas engine with the actually detected throttle opening. Patent Document 3 discloses a technique for determining a misfire when a decrease in pressure and an increase in oxygen concentration occur simultaneously on the exhaust side of a gas engine.

JP 2001-12293 A JP 2001-27148 A JP-A-5-133271

  However, the cause of misfire is not only the fixing of the injector described above, but also clogging or leakage of the fuel passage to the injector, defective spark plug, fuel deterioration, cylinder compression failure, various sensor failures, electrical system deterioration Various things can be considered. In this regard, even though it is possible to detect that misfire has occurred in the above-described prior art, it is not possible to determine what the cause is.

  In this regard, as a result of earnest research, the present inventor has found that the sticking of the injector in the gas fuel engine can be eliminated at least temporarily by an increase in the driving force of the injector, and the engine when the sticking is temporarily eliminated. It has been found that the parameters indicating the operating state (for example, exhaust pressure fluctuation and rotational speed fluctuation) are almost the same as in the case where there is no sticking.

  The present invention has been made in view of the above problems and new findings, and an object of the present invention is to provide means capable of supporting the identification of the cause in addition to detection of misfire.

  A first aspect of the present invention is a gas fuel engine misfire detection apparatus including misfire determination means for determining the presence or absence of misfire based on a first detection value indicating an operating state of a gas fuel engine, wherein the misfire determination means includes When it is determined that a misfire has occurred based on the first detection value, it further includes a driving force increasing means for increasing the driving force of the injector, and the misfire determining means is based on the second detection value in the increased state. A gas fuel engine misfire detection device that determines whether or not misfire has occurred.

  In the first aspect of the present invention, when the misfire determination means determines that there is misfire based on the first detection value indicating the operating state of the gas fuel engine, the driving force increase means increases the driving force of the injector. And a misfire determination means determines the presence or absence of misfire based on the 2nd detection value in the state which increased the driving force. When the misfire condition is resolved by the increase in the driving force, it can be estimated with high probability that the cause of the previous misfire is due to the fixation of the injector. Therefore, according to the first aspect of the present invention, the cause of misfire by the inspection operator can be specified. Can be suitably supported.

  The second aspect of the present invention is the gas fuel engine misfire detection apparatus according to claim 1, further comprising a determination result storage means for storing a determination result based on the second detection value. A fuel engine misfire detection device.

  In the second aspect of the present invention, since the determination result storage means for storing the determination result based on the second detection value is further provided, for example, the cause of misfire occurring during traveling is diagnosed at the time of inspection warehousing. Diagnosis can be performed at a different time from the occurrence.

  The third aspect of the present invention is the gas fuel engine misfire detection apparatus according to claim 1 or 2, further comprising a diagnostic means for outputting a cause of misfire based on an output of the misfire determination means. This is a gas fuel engine misfire detection device.

  In the third aspect of the present invention, the diagnostic means outputs the cause of misfire based on the output of the misfire determination means, so the inspection operator can easily identify the cause of misfire.

  A fourth aspect of the present invention is the gas fuel engine misfire detection apparatus according to claim 3, wherein the diagnosis unit determines that no misfire has occurred based on the second detection value by the misfire determination unit. A gas fuel engine misfire detection device that outputs that the cause of misfire is an injector stuck.

  As described with respect to the first aspect of the present invention, when the misfire state is resolved by increasing the driving force, it can be estimated with high probability that the cause of the previous misfire is the fixation of the injector. In the fourth aspect of the present invention, the logic is implemented in the apparatus and the result is output as the diagnosis result, so that the inspection operator can more easily identify the cause of misfire.

  5th this invention is the gas fuel engine misfire detection apparatus of Claim 3 or 4, Comprising: The said diagnostic means determines with the misfire determination based on the said 2nd detection value by a misfire determination means, and there exists misfire, and A gas fuel engine misfire detection apparatus that outputs that the cause of misfire exists in addition to injector fixation when the second detection value matches the first detection value within a predetermined range.

  If the misfire condition is not resolved even if the driving force increases, and the difference between the first detection value and the second detection value is small, the engine state does not change even if the driving force is increased. Therefore, it can be estimated with high probability that the cause of the previous misfire is other than the fixation of the injector. In the fifth aspect of the present invention, this logic is implemented in the apparatus and the result is output as the diagnosis result, so that the inspection operator can more easily identify the cause of misfire.

  A sixth aspect of the present invention is the gas fuel engine misfire detection apparatus according to any one of claims 3 to 5, wherein the diagnosis means determines that misfire is present based on the second detection value by the misfire determination means. And when the second detection value does not match the first detection value within a predetermined range, the fact that the cause of misfiring is stuck to the injector and the other exists is output. Device.

  Although the misfire state does not disappear even if the driving force increases, if there is some difference between the first detection value and the second detection value, the fixed state of the injector has been eliminated by the increase of the driving force. Therefore, it is possible to estimate with high probability that the cause of the previous misfire is due to the fixation of the injector and the other. In the sixth aspect of the present invention, this logic is implemented in the apparatus, and the result is output as the diagnosis result, so that the inspection operator can more easily identify the cause of misfire.

  A seventh aspect of the present invention is the gas fuel engine misfire detection apparatus according to any one of claims 3 to 5, further comprising a diagnosis result storage means for storing the output of the diagnosis means. A fuel engine misfire detection device.

  In the seventh aspect of the present invention, it is possible to refer to the diagnosis result at a time different from the occurrence of misfire. The diagnosis result storage means in the seventh aspect of the present invention may be a common storage medium with the determination result storage means in the second aspect of the present invention, or may be a separate storage medium.

  FIG. 1 is an overall schematic diagram of a gas fuel engine 1 according to an embodiment of the present invention. The gas fuel engine 1 is a port injection type CNG engine, and includes a cylinder block 2 and a cylinder head 3. In the cylinder block 2, a plurality of cylinders 4 extending in the vertical direction are arranged side by side in the thickness direction of the drawing, and in each cylinder 4, a piston 5 is accommodated so as to be able to reciprocate. Each piston 5 is connected to a common crankshaft 7 via a connecting rod 6. The reciprocating motion of each piston 5 is converted into the rotational motion of the crankshaft 7 via the connecting rod 6.

  Between the cylinder block 2 and the cylinder head 3, the upper side of each piston 5 is a combustion chamber 8. The cylinder head 3 is provided with an intake port 9 and an exhaust port 10 that allow communication between the outer side surfaces of the cylinder head 3 and the combustion chambers 8. In order to open and close these ports 9 and 10, an intake valve 11 and an exhaust valve 12 are supported on the cylinder head 3 so as to be able to reciprocate substantially in the vertical direction. In the cylinder head 3, an intake side camshaft 13 and an exhaust side camshaft 14 are rotatably provided above the intake valve 11 and the exhaust valve 12, respectively. Cams 15 and 16 for driving the intake valve 11 and the exhaust valve 12 are attached to the camshafts 13 and 14. Timing pulleys 17 and 18 provided at end portions of the camshafts 13 and 14 are connected to a timing pulley 19 provided at an end portion of the crankshaft 7 by a timing belt 20.

  An intake passage 30 including an air cleaner 31, a throttle valve 32, a surge tank 33, an intake manifold 34 and the like is connected to the intake port 9. Air (outside air) outside the gas fuel engine 1 passes through the portions 31, 32, 33, and 34 of the intake passage 30 in order toward the combustion chamber 8. The throttle valve 32 in this embodiment is a so-called electronic throttle, and is not directly mechanically coupled to the accelerator pedal of the driver's seat, but is driven by the throttle motor 37.

  Further, an injector 40 that injects fuel toward each combustion chamber 8 is attached to the intake port 9. The injector 40 is a conventionally known one that selectively injects fuel from a nozzle by reciprocating a plunger held in a solenoid coil by electromagnetic force. In the present embodiment, a booster circuit (not shown) is provided in the power supply system so that the drive voltage of the injector 40 can be selectively increased. Compressed natural gas (CNG), which is a fuel, is stored in a fuel cylinder 41, adjusted to a constant pressure by a regulator 44, and then supplied to an injector 40. The fuel injected from the injector 40 merges with the air introduced into the combustion chamber 8 through the intake passage 30, the intake port 9, and the intake valve 11, and becomes an air-fuel mixture.

  In order to ignite this air-fuel mixture, a spark plug 50 is attached to the cylinder head 3. Each cylinder is provided with an ignition coil 52 with a built-in igniter that is coupled to the ignition plug 50 independently for each cylinder. At the time of ignition, the igniter controls energization and interruption of the primary current in the ignition coil 52 with built-in igniter for each cylinder that has received the ignition signal, and the secondary current is supplied to the spark plug 50.

  The burned air-fuel mixture is guided to the exhaust port 10 through the exhaust valve 12 as exhaust gas. An exhaust passage 60 having an exhaust manifold 61, a catalytic converter 62, and the like is connected to the exhaust port 10, and the exhaust gas is purified and discharged through these.

Various sensors are attached to the gas fuel engine 1. A water temperature sensor 74 for detecting the temperature of the cooling water of the gas fuel engine 1 is attached to the cylinder block 2. In the intake passage 30, in the vicinity of the throttle valve 32, there are a throttle opening sensor 72 that detects the rotation angle of the shaft and an accelerator opening sensor that detects an accelerator operation amount (also referred to as an accelerator depression amount, an accelerator opening degree, etc.). 77. The surge tank 33 is provided with a vacuum sensor 71 for detecting a negative pressure (intake pipe pressure PM) therein. An injection pressure sensor 78 for detecting the fuel injection pressure is provided in the fuel pipe connecting the regulator 44 and the injector 40. The exhaust manifold 61 is provided with an O ₂ sensor 79 for detecting the oxygen concentration in the exhaust gas.

  Further, the camshaft 13 is provided with a crank reference position sensor 80 that generates a reference position detection pulse every 720 ° CA in terms of a crank angle (CA). The crankshaft 7 is provided with a crank angle sensor 81 that generates a pulse for detecting a crank angle or a rotational speed every 30 ° CA. In the electronic control unit (ECU) 90, every time a pulse signal of the crank angle sensor 81 is input, the crank angular velocity is calculated from the pulse interval, and the data is stored in the internal memory as the crank angular velocity.

  The ECU 90 is a microcomputer system that executes a misfire determination diagnosis process described below and fuel injection control, ignition timing control, etc. performed separately from the present invention. Various types of maps are executed according to programs and various maps stored in the memory. A signal from the sensor is input, calculation processing is executed based on the input signal, and various actuator control signals are output based on the calculation result. The ECU 90 is connected to a nonvolatile memory 91 as an external storage device. As the nonvolatile memory 91, it is preferable to use a semiconductor element such as a flash memory in addition to a magnetic storage medium such as a hard disk.

  The misfire determination diagnosis process in the first embodiment configured as described above will be described below. In FIG. 2, it is first determined whether or not injector characteristic check control, which will be described later, is being performed (S10). This determination is made by referring to a predetermined check control execution flag exinjfixck that is turned on during execution of the control, and is affirmed because it is not executed here.

  Next, the crank angular velocity deviation is detected (S15). This deviation is based on the pulse signal from the crank angle sensor 81 provided on the crankshaft 7 and in the time required for the crankshaft 7 to rotate at a predetermined crank angle and the combustion cycle of the other cylinder immediately before that. It is determined based on the time required to rotate the predetermined crank angle. Next, a first misfire determination is performed based on this deviation (S20). This determination is made based on whether a predetermined parameter indicating the operating state of the engine exceeds the misfire determination criterion. In this embodiment, the deviation detected in step S15 is equal to the predetermined misfire determination reference value. If so, it is identified that a misfire has occurred in the combustion cycle of that cylinder. When the frequency of occurrence of misfire exceeds the reference value, it is determined that misfire has been detected in the engine. If it is not determined that there is a misfire, the process ends because there is no need for a diagnostic process.

  If it is determined that there is a misfire, it is determined whether the injector characteristic check control has not been performed (S30). This determination is made by referring to a predetermined check controlled flag exinjfixend that is turned on when the control is started, and is affirmed because it has not been executed.

  Next, injector characteristic check control is started (S40). This injector characteristic check control is specifically a process for increasing the driving force of the injector 40, and is performed, for example, by increasing the driving voltage applied to the solenoid coil of the injector 40. When the injector characteristic check control is started, the check control execution flag exinjfixck is turned on.

  Next, the determination in step S10 is performed again. Here, the check control in-execution flag exinjfixck is on, so that the determination is negative. Next, a deviation in crank angular velocity is detected (S45). This deviation is obtained by the same method as that performed previously in step S15. Next, it is determined by referring to a predetermined software timer whether a predetermined time has elapsed since the start of the injector characteristic check control (S50). Thereafter, the determinations in steps S10 and S50 and the detection in step S45 are repeatedly performed until a predetermined time elapses. When the predetermined time elapses, the injector characteristic check control is terminated, and the flags exinjfixck and exinjfixend are inverted.

  Then, a second misfire determination is performed (S70). This second misfire determination is performed by the same method as the first misfire determination previously performed in step S20, but the latest value sampled at this time is used as the deviation of the crank angular velocity used here. (That is, the detection value in a state where the driving force is increased) is used.

  If the determination in step S70 is negative (that is, if the misfire state has been eliminated by increasing the driving force), the process proceeds to step S110. When the misfire state is resolved by the increase in driving force, it can be estimated with high probability that the cause of the previous misfire is the fixation of the injector 40. For this reason, in step S110, an output indicating that the cause of misfire is due to injector sticking is performed, and the process is terminated.

  If the determination in step S70 is affirmative (that is, if the misfire condition is not resolved even if the driving force is increased), it is next determined whether the misfire symptom is improved (S80). Specifically, this determination is made based on whether or not the detection value at the time of increasing driving force sampled in step S70 matches the detection value previously sampled in step S20 within a predetermined error range. If there is no improvement, the result is negative. If they do not agree with each other and are out of the improvement side, the result is positive.

  If the determination in step S80 is negative (that is, the misfire state is not resolved even if the driving force is increased and the symptom of the misfire is not improved), the engine state is changed even if the driving force is increased. Since there is no case, it can be estimated with high probability that the cause of the previous misfire is other than the fixing of the injector 40. For this reason, in step S100, an output indicating that the cause of misfire is other than injector fixation is performed, and the process is terminated.

  On the other hand, if the determination in step S80 is affirmative (that is, the misfire condition is not resolved even if the driving force is increased, but the symptom of misfiring is improved), the fixed state of the injector is increased by the increase of the driving force. Although it has been resolved, other causes still exist, so it can be estimated with high probability that the cause of the previous misfire is due to the fixation of the injector 40 and the other. For this reason, in step S90, an output indicating that the cause of the misfire is in both the injector fixing and the other is performed, and the process is terminated.

  The output in steps S90, 100, and 110 is performed by writing a predetermined diagnostic code to a diagnostic log file stored in the nonvolatile memory 91. This diagnostic log file is read from the nonvolatile memory 91 when it is connected to an external diagnostic terminal provided in a repair shop or the like, and is referred to by an inspection operator and used for diagnosis and repair.

  As described above, in the present embodiment, when the first misfire determination during the normal operation of the gas fuel engine 1 determines that there is a misfire based on the first detection value (S20), the driving force of the injector 40 is changed. Increase (S40), based on the second detection value in the state where the driving force is increased, the presence or absence of misfire is determined by the second misfire determination (S70). When the misfire state is resolved by the increase in the driving force, it is possible to estimate with high probability that the cause of the misfire in the first misfire determination is the sticking of the injector 40. According to this embodiment, the inspection worker The cause of misfire caused by can be suitably supported.

  Moreover, in this embodiment, since the cause of misfire is output based on the result of the second misfire determination (S90, S100, S110), the inspection operator can easily identify the cause of misfire.

  Further, in the present embodiment, “when the misfire state is resolved by the increase in driving force, it can be estimated that the cause of the previous misfire is due to the fixation of the injector” (S110), “Even if the driving force is increased, the engine If there is no change in the state, it can be estimated that the cause of the previous misfire is other than the fixing of the injector ”(S100),“ Although the misfire state is not resolved even by an increase in driving force, the first detected value and the first When there is some difference between the two detection values, that is, the first detection value and the second detection value do not match within a predetermined range, and the second detection value is out of the misfire improvement side. In this case, it is possible to estimate that the cause of the previous misfire is due to both the fixation of the injector and the other "(S90). Inspection worker misfires It can be further easily identify the cause.

  Further, in the present embodiment, since the nonvolatile memory 91 is further provided as a diagnostic result storage means for storing the diagnostic result, for example, the cause of misfire that occurs during traveling is diagnosed at the time of inspection warehousing, Diagnosis can be made at different times.

  In the above embodiment, the system is configured to output the diagnosis result by writing to the diagnosis log file. However, the output of the diagnosis result is a warning message in the passenger compartment, a language message in the display device, or a voice message. Or you may perform in real time with respect to the predetermined | prescribed terminal outside a vehicle via a wireless data communication network.

  Moreover, in the said embodiment, although it was set as the structure which outputs the kind of estimated cause as a diagnostic result, it replaces with such a structure (or in addition to such a structure), 2nd misfire determination (S70). The determination result, that is, only the presence or absence of misfire in the second misfire determination may be output (stored in the nonvolatile memory 91), and even with such a configuration, the inspection worker who refers to this may easily cause the misfire The desired effect of the present invention can be obtained.

  Further, in the above embodiment, the misfire determination is performed based on the deviation of the crank angular speed, which is the rotational speed fluctuation of the crankshaft 7, but the misfire determination in the present invention is based on the combustion pressure such as the exhaust pressure waveform of the engine. , By comparing the throttle opening estimated from the output of the gas engine with the actually detected throttle opening, by monitoring the decrease in pressure and oxygen concentration on the exhaust side, by combustion light, by ignition Various conventionally known methods such as those based on the current value of the system can be used, and all belong to the category of the present invention. Moreover, although the said embodiment demonstrated the example which applied this invention about the port injection type engine, this invention is applicable not only to a port injection engine but to a direct injection engine. Furthermore, although the said embodiment demonstrated the example which applied this invention about the CNG engine, this invention is widely applicable also to other types of gaseous fuel engines, such as an LPG engine.

1 is an overall schematic diagram of a misfire detection device according to an embodiment of the present invention. It is a flowchart which shows the misfire determination diagnostic process in embodiment of this invention.

Explanation of symbols

1 Gas Fuel Engine 40 Injector 81 Crank Angle Sensor 90 Electronic Control Unit (ECU)
91 Nonvolatile memory

Claims (7)

A gas fuel engine misfire detection device comprising misfire determination means for determining the presence or absence of misfire based on a first detection value indicating an operating state of a gas fuel engine,
When the misfire determination means determines a misfire based on the first detection value, the misfire determination means further includes a driving force increasing means for increasing the driving force of the injector,
The gas fuel engine misfire detection device, wherein the misfire determination means determines the presence or absence of misfire based on the second detection value in the increased state. A gas fuel engine misfire detection device according to claim 1,
A gas fuel engine misfire detection apparatus, further comprising determination result storage means for storing a determination result based on the second detection value. A gas fuel engine misfire detection device according to claim 1 or 2,
A gas fuel engine misfire detection apparatus, further comprising diagnostic means for outputting a cause of misfire based on an output of the misfire determination means. A gas fuel engine misfire detection device according to claim 3,
The gas fuel engine misfire detection device characterized in that the diagnostic means outputs that the cause of the misfire is injector sticking when it is judged by the misfire judgment means that there is no misfire based on the second detection value. . A gas fuel engine misfire detection device according to claim 3 or 4,
The diagnostic means determines that there is a misfire based on the second detection value by the misfire determination means, and the cause of the misfire is when the second detection value matches the first detection value within a predetermined range. A gas fuel engine misfire detection device that outputs that there is something other than an injector fixed. A gas fuel engine misfire detection device according to any one of claims 3 to 5,
The diagnostic means determines that there is a misfire based on the second detection value by the misfire determination means, and the cause of the misfire is when the second detection value does not coincide with the first detection value within a predetermined range. A gas fuel engine misfire detection device that outputs that the injector is stuck and that the other exists. A gas fuel engine misfire detection device according to any one of claims 3 to 5,
A gas fuel engine misfire detection device further comprising diagnostic result storage means for storing the output of the diagnostic means.

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