JP2009203938A - Control device and control method of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of impairing reliability of a detection value, when a part of a deposit mixed in a combustion chamber sticks to and deposits on a surface of a heating tube and an inner wall of a small diameter part to form sliding resistance of a pressure receiving part, in an internal combustion engine incorporated with a glow plug-integrated cylinder internal pressure sensor. <P>SOLUTION: This control method of the internal combustion engine is provided by using the glow plug integrated cylinder internal pressure sensor of constituting the pressure receiving part of the cylinder internal pressure sensor 26 for detecting pressure in a combustion chamber 12 of an engine 10, out of the heating tube for internally storing a heater element of a glow plug 38, and determines whether or not the engine 10 is a predetermined operation state, and calculates hysteresis of an actual wave of cylinder internal pressure actually detected to a reference waveform of the preset cylinder internal pressure when the engine 10 is the predetermined operation state, and compares the calculated hysteresis with a preset first threshold value, and removes a deposit sticking to the pressure receiving part by carrying an electric current to the heater element when the calculated hysteresis is larger than the first threshold value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device and control method for an internal combustion engine using a glow plug integrated cylinder pressure sensor.

In an internal combustion engine of the compression ignition type, or to guess the cetane number of the fuel, or to detect the misfire, or to achieve a low NO _X combustion, it is practical to control the ignition timing using the cylinder pressure sensor It's getting on. In addition, although a spark ignition type internal combustion engine does not require a spark plug in a compression ignition type internal combustion engine, instead of a glow plug or a direct injection type fuel injection valve, an intake / exhaust valve and a valve mechanism thereof At the same time, it must be incorporated into the cylinder head. For this reason, particularly in a compression ignition type internal combustion engine having a plurality of intake and exhaust valves, it is extremely difficult to secure a space for mounting the above-described in-cylinder pressure sensor.

  Accordingly, Patent Document 1 discloses a technique that overcomes the problem of restriction on the mounting space of the in-cylinder pressure sensor by integrating the glow plug and the in-cylinder pressure sensor and directly setting the mounting position of the glow plug as the mounting position of the in-cylinder pressure sensor. Has been proposed. In this in-cylinder in-cylinder pressure sensor, the pressure receiving portion of the in-cylinder pressure sensor facing the combustion chamber is configured by a glow plug heat generating tube in which a heater element is housed. Therefore, the heat generating tube of the glow plug, which is the pressure receiving portion, is displaced with the pressure fluctuation in the combustion chamber, and this displacement is detected using a piezoelectric element or the like.

  The mounting hole formed in the cylinder head for accommodating the glow plug integrated cylinder pressure sensor accommodates a small diameter portion surrounding the elongated heat generating tube and facing the combustion chamber, and the casing of the glow plug integrated cylinder pressure sensor. And a step portion connecting the small diameter portion and the large diameter portion. The tip of the casing is in close contact with the stepped portion, thereby holding the small diameter portion and the combustion chamber side in a sealed state.

JP 2002-339793 A

In an internal combustion engine of the compression ignition type glow plug integrated cylinder pressure sensor is mounted, the deposit such as PM (P articulate M atter) typified by carbon compounds such as carbon fine particles and hydrocarbons contained in the EGR gas Since it is mixed in the combustion chamber, a part of this deposit may also enter between the heat generating tube and the small diameter portion of the mounting hole and adhere and accumulate on the surface of the heat generating tube and the inner wall of the small diameter portion. If the deposit adheres to and accumulates on the surface of the heat generating tube or the inner wall of the small diameter portion, this becomes the sliding resistance of the pressure receiving portion, which may impair the smooth displacement and cause hysteresis in the detected pressure change. In such a case, the characteristics of the in-cylinder pressure sensor change, so that the change in pressure in the combustion chamber cannot be detected accurately, and various problems may occur when performing combustion control of the internal combustion engine.

  In a compression ignition internal combustion engine, the supply of fuel is stopped during deceleration of the vehicle when the accelerator opening is 0. At this time, the glow plug is energized to heat the heat generating tube and adhere to the surface of the heat generating tube. It is possible to oxidize and remove the deposit. From this point of view, it is effective to grasp the hysteresis of the detection value of the glow plug integrated cylinder pressure sensor due to deposit adhesion and to remove this.

  An object of the present invention is to provide a control device and a control method for an internal combustion engine in which a glow plug integrated cylinder pressure sensor is incorporated.

  According to a first aspect of the present invention, a glow plug-integrated cylinder in which a pressure receiving portion of a cylinder pressure sensor for detecting the pressure in a combustion chamber of an internal combustion engine is constituted by a heat generating tube in which a glow plug heater element is housed. Hysteresis calculation that calculates the hysteresis of the actual waveform of the in-cylinder pressure detected by the glow plug-integrated in-cylinder pressure sensor with respect to a preset reference waveform of the in-cylinder pressure when the internal pressure sensor and the internal combustion engine are in a predetermined operating state And a glow plug drive determination comparison unit that compares the hysteresis calculated by the hysteresis calculation unit with a preset first threshold, and the comparison result of the glow plug drive determination comparison unit A control device for an internal combustion engine, comprising: a heater energization control unit that controls energization of the heater element.

  In the present invention, when the internal combustion engine is in a predetermined operating state, the hysteresis of the actual waveform of the in-cylinder pressure detected by the glow plug-integrated in-cylinder pressure sensor with respect to a preset reference waveform of the in-cylinder pressure is generated in the hysteresis calculation unit. Is calculated. Next, the hysteresis calculated by the hysteresis calculator is compared with a first threshold value set in advance by the glow plug drive determination comparator. The heater energization control unit controls energization to the heater element based on the comparison result in the glow plug drive determination comparison unit.

  In the control apparatus for an internal combustion engine according to the first aspect of the present invention, the heater energization control unit applies the heater element to the heater element when the glow plug drive determination comparison unit determines that the calculated hysteresis is greater than the first threshold value. May be used to energize.

  A sensor failure determination comparison unit that compares the hysteresis calculated again by the hysteresis calculation unit with the second threshold value set in advance after the heater element is energized by the heater energization control unit; Can do.

  A glow plug integrated in-cylinder pressure sensor is arranged for each cylinder of the internal combustion engine. After the heater energization control unit energizes the heater element, the hysteresis calculation unit recalculates the hysteresis for each cylinder. A fuel supply system failure determination comparator for comparison may be further provided.

  The heater energization control unit controls the energization of the heater element based on the operation state of the internal combustion engine in addition to the comparison result in the glow plug drive determination comparison unit. The heater energization control unit controls the heater element. A lower heating value calculation unit that calculates a lower heating value of the internal combustion engine after energization, and a misfire determination unit that determines the presence or absence of misfire based on the lower heating value calculated by the lower heating value calculation unit Can be prepared. In this case, the heater energization control unit determines that the calculated hysteresis is larger than the first threshold value, and the glow plug drive determination comparison unit determines that the heater element is in a low-load operation state. It may be one that conducts electricity. In addition, it is possible to further include an operation condition changing unit that changes the operation condition of the internal combustion engine of the internal combustion engine based on the determination result in the misfire determination unit.

  According to a second aspect of the present invention, a glow plug-integrated cylinder in which a pressure receiving portion of a cylinder pressure sensor for detecting a pressure in a combustion chamber of an internal combustion engine is configured by a heat generating tube in which a heater element of the glow plug is accommodated. A method for controlling an internal combustion engine using an internal pressure sensor, the step of determining whether or not the internal combustion engine is in a predetermined operating state, and a reference of a preset in-cylinder pressure when the internal combustion engine is in a predetermined operating state A step of calculating a hysteresis of the actual waveform of the in-cylinder pressure actually detected with respect to the waveform, a step of comparing the calculated hysteresis with a first threshold value set in advance, and the heater element based on the comparison result And a step of controlling the energization to.

  In the internal combustion engine control method according to the second aspect of the present invention, the step of controlling energization to the heater element energizes the heater element when the calculated hysteresis is larger than the first threshold value. It's okay.

  A step of comparing a hysteresis calculated first after energizing the heater element with a second threshold value set in advance, and a step of determining the presence or absence of a failure of the glow plug integrated sensor based on the comparison result And determining whether or not the glow plug integrated sensor has failed is determined that the glow plug integrated sensor has failed if the calculated hysteresis is greater than a preset second threshold value. It may be.

  A step of comparing the hysteresis of each cylinder, which is calculated first after energizing the heater element, is provided for each cylinder of the internal combustion engine, and a comparison result is obtained. And determining whether there is an abnormality in the fuel injection system based on the above. In this case, the step of determining whether or not there is an abnormality in the fuel injection system is performed when the hysteresis in any one cylinder is different from the hysteresis in the other remaining cylinders by a predetermined value or more, the fuel injection system for this one cylinder is It may be determined to be abnormal.

  The step of controlling energization to the heater element is performed based on the operation state of the internal combustion engine in addition to the comparison result between the calculated hysteresis and the first threshold value. The method may further include a step of calculating a calorific value and a step of determining the presence or absence of misfire based on the calculated lower calorific value. In this case, the step of controlling energization to the heater element energizes the heater element when the calculated hysteresis is larger than the first threshold and the internal combustion engine is in a low-load operation state. Good.

  The method may further include a step of changing the operating condition of the internal combustion engine of the internal combustion engine based on the determination result of the presence or absence of misfire.

  According to the present invention, when the internal combustion engine is in a predetermined operating state, the hysteresis of the actual waveform of the in-cylinder pressure actually detected with respect to the preset reference waveform of the in-cylinder pressure is calculated and this is set in advance. Compared with the threshold value of 1 and controlled the energization to the heater element based on the comparison result, when the calculated hysteresis is larger than the first threshold value, by energizing the heater element, Deposits adhering to the pressure receiving portion can be disassembled and removed. Thereby, the reliability of the detection value by the glow plug integrated cylinder internal pressure sensor can be maintained over a long period of time.

  After energizing the heater element, the initially calculated hysteresis is compared with a preset second threshold value, and the presence / absence of a failure of the glow plug integrated sensor is determined based on the comparison result. In this case, when the calculated hysteresis is larger than the second threshold value set in advance, it can be determined that the glow plug integrated sensor has failed.

  A glow plug integrated in-cylinder pressure sensor is arranged for each cylinder of the internal combustion engine, and the hysteresis calculated for each cylinder first calculated after energizing the heater element is compared with each other. When it is determined whether there is an abnormality in the fuel injection system, when the hysteresis in any one cylinder is different from the hysteresis in the other remaining cylinders by a predetermined value or more, the fuel injection system for this one cylinder is abnormal. It can be determined that there is.

  If the heater element is energized to calculate the lower heating value of the internal combustion engine based on the comparison result between the calculated hysteresis and the first threshold value set in advance and the operating state of the internal combustion engine, a misfire may occur. The presence or absence of can be determined. Further, when the operation condition of the internal combustion engine of the internal combustion engine can be changed based on the determination result of the presence or absence of misfire, it is possible to avoid the occurrence of misfire and to stably operate the internal combustion engine.

  Embodiments of the present invention will be described in detail with reference to FIG. 1 to FIG. 7, but the present invention is not limited to these embodiments, and these may be further combined as necessary or belong to the spirit of the present invention. It can be applied to any other technology.

  The concept of the engine system in this embodiment is shown in FIG. 1, and the control block in this engine system is shown in FIG. The engine 10 in the present embodiment is a compression ignition type multi-cylinder internal combustion engine that spontaneously ignites by directly injecting light oil as fuel into the combustion chamber 12 in a compressed state from the fuel injection valve 11. In a form, this may be a single cylinder internal combustion engine. The engine 10 normally burns using an exhaust gas recirculation (EGR) device (not shown) that guides part of the exhaust gas flowing in the exhaust passage 13 to the intake passage 14 and the kinetic energy of the exhaust gas flowing in the exhaust passage 13. A turbocharger (not shown) for supercharging the chamber 12 is incorporated.

  The cylinder head 17 formed with the intake port 15 and the exhaust port 16 respectively facing the combustion chamber 12 includes a valve operating mechanism (not shown) including an intake valve 18 that opens and closes the intake port 15 and an exhaust valve 19 that opens and closes the exhaust port 16. Is incorporated. The cylinder head 17 is also provided with a fuel injection valve 11 that faces the center of the upper end of the combustion chamber 12 so as to be sandwiched between the intake valve 18 and the exhaust valve 19. The valve operating mechanism in the present embodiment can change the opening / closing timings of the intake valve 18 and the exhaust valve 19 according to the operating state of the engine 10, but these opening / closing timings may be fixed. .

  An oxidation catalyst 21 for detoxifying harmful components contained in the exhaust is disposed in the middle of the exhaust pipe 20 connected to the cylinder head 17 so as to communicate with the exhaust port 16 and defining the exhaust passage 13 together with the exhaust port 16. Etc. are incorporated.

  Accordingly, the intake air supplied into the combustion chamber 12 from the intake pipe 22 that is connected to the cylinder head 17 so as to communicate with the intake port 15 and defines the intake passage 14 together with the intake port 15 is supplied from the fuel injection valve 11 to the combustion chamber. 12 forms an air-fuel mixture with the fuel injected into the fuel cell 12. In general, the piston 23 spontaneously ignites and burns immediately before the compression top dead center of the piston 23, and exhaust gas generated thereby is discharged from the exhaust pipe 20 into the atmosphere through the oxidation catalyst 21.

  In the present embodiment, in order to grasp the operating state of the engine 10 and the vehicle on which the engine 10 is mounted, the injection valve drive control unit 25 of the ECU 24 controls the fuel injection amount and the injection timing from the fuel injection valve 11. Various sensors such as an in-cylinder pressure sensor 26, an accelerator opening sensor 27, an air flow meter 28, a water temperature sensor 29, a crank angle sensor 30, and the like are provided. The in-cylinder pressure sensor 26 detects the pressure in the combustion chamber 12 of the engine 10 and outputs it to the operating state determination unit 31 and the waveform calculation unit 32 of the ECU 24. The accelerator opening sensor 27 detects the amount of depression of the accelerator pedal 33 operated by the driver, and outputs this to the driving state determination unit 31 of the ECU 24. The air flow meter 28 detects the amount of intake air flowing into the combustion chamber 12 through the intake passage 14 and outputs this to the ECU 24. The water temperature sensor 29 detects the temperature of the cooling water in the water jacket 35 formed in the cylinder block 34 in which the piston 23 reciprocates, and outputs this to the operating state determination unit 31 of the ECU 24. The crank angle sensor 30 attached to the cylinder block 34 detects the rotational phase of the crankshaft 37 to which the piston 23 is connected via the connecting rod 36 and outputs this to the operating state determination unit 31 and the waveform calculation unit 32 of the ECU 24. To do.

  The in-cylinder pressure sensor 26 in the present embodiment is a glow plug having a pressure receiving portion (not shown) facing the combustion chamber 12 and a heat generating tube in which a heater element (not shown) of a glow plug 38 integrated with the in-cylinder pressure sensor 26 is accommodated. It is a body shape cylinder pressure sensor. The specific structure of such a glow plug-integrated in-cylinder pressure sensor is well known in Patent Document 1 and the like.

  The ECU 24 includes a microcomputer including a CPU, ROM, RAM, A / D converter, input / output interface, and the like (not shown). The ECU 24 performs predetermined calculation processing based on the detection signals from the sensors 26 to 29 described above so that the engine 10 can be smoothly operated. Then, the operation of the fuel injection valve 11 and the like is controlled according to a preset program. For this reason, an injection valve drive control unit 39 for setting and driving the injection timing and injection amount of the fuel injection valve 11, and a heater energization control unit for controlling on / off of energization to the heater element of the glow plug 38 40.

  In addition, the ECU 24 in this embodiment determines whether there is an abnormality in the in-cylinder pressure sensor 26 and a fuel supply system from a fuel tank (not shown) to the fuel injection valve 11, so In addition, a reference waveform storage unit 41, a hysteresis calculation unit 42, a drive determination comparison unit 43, a failure determination comparison unit 44, and a warning indicator drive control unit 45 are further provided.

  The driving state determination unit 31 grasps the driving state of the engine 10 based on detection signals from the various sensors 26 to 29 and determines whether or not the engine 10 is in a predetermined driving state. In this case, the predetermined operation state in the present embodiment is a motoring state, that is, a fuel cut state in which the opening degree of the accelerator pedal 33 becomes 0 during operation of the engine 10 and fuel is not injected from the fuel injection valve 11. Point to. Information regarding the operating state of the engine 10 ascertained by the operating state determination unit 31 is also output to the injection valve drive control unit 39, the heater energization control unit 40, and the reference waveform storage unit 41.

  The waveform calculation unit 32 acquires the change in the in-cylinder pressure as shown in FIG. 3 based on the detection information from the in-cylinder pressure sensor 26 and the crank angle sensor 30, and outputs this to the hysteresis calculation unit 42. In the upper graph of FIG. 3, the horizontal axis represents the crank angle phase, the vertical axis represents the pressure, and the two-dot chain line in FIG. 3 is a normal in-cylinder pressure waveform in which no deposit is deposited and deposited. A solid line indicates a state in which hysteresis is caused by adhesion deposition. The lower graph in FIG. 3 shows the magnitude of the pressure error of the waveform in a state where hysteresis has occurred with respect to the normal pressure waveform, and changes greatly before and after TDC (compression top dead center), and in particular, TDC. It will be recognized that the maximum is immediately after.

  The reference waveform storage unit 41 stores in advance a normal in-cylinder pressure waveform in which deposits are not deposited and accumulated as shown by a two-dot chain line in FIG. 3. In this embodiment, the operating state of the engine 10, for example, air flow is stored. Several types are prepared according to the intake air amount detected by the meter 28, the number of revolutions of the crankshaft 37 that can be calculated based on the detection signal from the crank angle sensor 30, the load of the engine 10, and the like. The reference waveform storage unit 41 selects a waveform corresponding to the operation state of the engine 10 at the time of detection by the in-cylinder pressure sensor 26 from the stored reference waveforms based on the output from the operation state determination unit 31. And output to the hysteresis calculation unit 42. In addition, based on the information from the in-cylinder pressure sensor 26 in the compression stroke of the piston having a relatively small hysteresis, a reference waveform as shown by a two-dot chain line in FIG. Is possible. In this case, there is an advantage that it is not necessary to store a large number of reference waveforms corresponding to the operating state of the engine 10 in the reference waveform storage unit 41, but it is necessary that the in-cylinder pressure sensor 26 does not fail. Become.

  When the internal combustion engine is in a predetermined operation state, that is, in a motoring state, the hysteresis calculation unit 42 is actually calculated by the waveform calculation unit 32 with respect to the reference waveform of the predetermined in-cylinder pressure stored in the reference waveform storage unit 41. The hysteresis ΔH of the in-cylinder pressure waveform is calculated. More specifically, the pressure difference between the output waveform from the waveform calculation unit 32 and the output waveform from the reference waveform storage unit 41 is acquired as an absolute value for each predetermined crank angle phase, and these are added. When deposits are deposited and accumulated to some extent on the pressure receiving portion of the in-cylinder pressure sensor 26, a large pressure difference appears before and after the TDC as shown in the lower graph of FIG. In the present embodiment, this is output as hysteresis ΔH to the drive determination comparison unit 43 and the failure determination comparison unit 44.

The drive determination comparison unit 43 compares the hysteresis ΔH calculated by the hysteresis calculation unit 42 with a preset first threshold value H _R1 . The first threshold value H _R1 is a minimum amount such that the amount of deposit deposited on the pressure receiving portion of the in-cylinder pressure sensor 26 is not reliable as a measurement value of the in-cylinder pressure sensor 26. Therefore, when the hysteresis ΔH calculated by the hysteresis calculation unit 42 is larger than the first threshold value H _R1 , it means that it is necessary to remove the deposit. The comparison result in the drive determination comparison unit 43 is output to the heater energization control unit 40.

The failure determination comparison unit 44 in this embodiment includes a timer (not shown) that starts counting up after the heater energization control unit 40 energizes the heater element to finish the deposit removal process. The failure determination comparison unit 44 compares the hysteresis ΔH calculated again by the hysteresis calculation unit 42 with a preset second threshold value H _R2, and based on the comparison result and the count value of the timer, the in-cylinder pressure It is determined whether the sensor 26 has a failure and whether the fuel supply system has an abnormality. More specifically, when the calculated hysteresis ΔH becomes larger than the second threshold value H _R2 immediately after the deposit removal process is completed, no deposit is deposited on the pressure receiving portion of the in-cylinder pressure sensor 26. Therefore, it is determined that there is an abnormality in the fuel supply system. Further, when the calculated hysteresis ΔH becomes larger than the second threshold value H _R2 after a predetermined time has elapsed after the deposit removal process, it is determined that the in-cylinder pressure sensor 26 itself has failed. The determination result in the failure determination comparison unit 44 is output to the warning indicator drive control unit 45.

  The injection valve drive control unit 39 sets the injection amount and the injection timing of the fuel injected from the fuel injection valve 11 based on the output information from the operation state determination unit 31, and drives the fuel injection valve 11 according to the setting conditions. To do.

The heater energization control unit 40 controls energization of the glow plug 38 to the heater element based on the comparison result in the drive determination comparison unit 43. More specifically, when the drive determination comparison unit 43 determines that the hysteresis ΔH calculated by the hysteresis calculation unit 42 is larger than the first threshold value H _R1 , the heater element is energized (for example, about 1 minute). ) To remove the deposit deposited on the pressure receiving portion. Even when the cooling water temperature detected by the water temperature sensor 29 is equal to or lower than a predetermined temperature as in the cold start, the heater element is energized, thereby increasing the temperature in the combustion chamber 12 and igniting the fuel. Improve sexiness.

  The warning indicator drive control unit 45 is for informing a driver or the like of an abnormality in the fuel supply system or a failure in the in-cylinder pressure sensor 26 based on the determination result in the failure determination comparison unit 44. A display 46 is provided in a vehicle interior (not shown). The warning indicator 46 may be any device that can alert the driver of the vehicle using hearing or vision.

  Such a control procedure in the present embodiment is shown in FIG. First, in step S11, it is determined whether or not the engine 10 is in a predetermined operation state. Only when it is determined that the engine 10 is in a predetermined operation state, that is, in a motoring state, the process proceeds to step S12 and the reference waveform is read. I do. Subsequently, in-cylinder pressure is detected in step S13, and the actual waveform is calculated in step S14.

Next, the waveform hysteresis ΔH is calculated in step S15, and it is determined whether or not the flag is set in step S16. Since the flag is not initially set, the process proceeds to step S17, and it is determined whether or not the waveform hysteresis ΔH calculated in step S15 is larger than a first threshold value H _R1 set in advance. Here, the waveform hysteresis ΔH calculated is equal to or less than the first threshold value H _R set in advance, that is, when the magnitude of the waveform hysteresis ΔH is determined to sufficiently small deposit to the pressure receiving portion of the cylinder pressure sensor 26 Does not deposit so much, so the process returns to step S11 without doing anything.

In contrast, the calculated waveform hysteresis ΔH is larger than the preset first threshold value H _R1 , that is, a deposit that has an adverse effect on the operation control of the engine 10 adheres to the pressure receiving portion of the in-cylinder pressure sensor 26. If it is determined that there is a possibility of accumulation, the process proceeds to step S18, the heater element of the glow plug 38 is energized, and the deposit deposited on the pressure receiving portion of the in-cylinder pressure sensor 26 is removed. The flag is set in step S19, and the process returns to step S11 again.

On the other hand, if it is determined that the flag is set in step S16, that is, the deposit removal process is performed in step S18, the process proceeds to step S20 and the counter count value C is incremented by one. Then, it is determined again whether the waveform hysteresis ΔH calculated in the immediately preceding step S15 is larger than a preset second threshold value H _R2 . Here, when it is determined that the calculated waveform hysteresis ΔH is equal to or less than the second threshold value H _R2 , that is, the magnitude of the waveform hysteresis ΔH is sufficiently small, the deposit is attached to the pressure receiving portion of the in-cylinder pressure sensor 26 so much. Since it is not deposited, the process returns to step S11 without doing anything.

However, when it is determined that the calculated waveform hysteresis ΔH is larger than the second threshold value H _R2 , that is, there is a possibility that some other problem has occurred, the process proceeds to step S22 and the process of step S20 is performed. the count value C of the counter in step is equal to or greater than a predetermined value C _R. Here, the count value C of the counter is less than the predetermined value C _R, that is, when it is determined that some abnormality occurred waveform hysteresis ΔH in the fuel supply system is rapidly increased, the process proceeds to S23 in step Then, after a warning notifying that there is a failure in the fuel supply system is output to the warning indicator 46, the process proceeds to step S24, the flag is reset, and a series of control is terminated.

The count value of the counter at S22 in step C is a predetermined value or more C _R, i.e. although abnormality is not in a fuel supply system, if it is determined that there is an abnormality in the output of the in-cylinder pressure sensor 26, the S24 After shifting to the step and outputting a warning notifying that the in-cylinder pressure sensor 26 has failed to the warning indicator 46, the process proceeds to the previous step S24 and a series of control is terminated.

  In this way, deposits deposited and deposited on the pressure receiving portion of the in-cylinder pressure sensor 26 can be removed at an appropriate time, and the fuel supply system is based on the rate of change of the waveform hysteresis ΔH calculated after the deposit removal. It is possible to determine whether or not there is any abnormality or failure of the in-cylinder pressure sensor 26 itself.

In the multi-cylinder internal combustion engine as in the present embodiment, the in-cylinder pressure sensor 26 as described above can be incorporated in each cylinder. In this case, the hysteresis calculating unit 42 calculates the hysteresis of the actual waveform of the in-cylinder pressure detected by each in-cylinder pressure sensor 26 for each cylinder. When the drive determination comparison unit 43 determines that at least one of the in-cylinder pressure hysteresis ΔH in each cylinder is greater than the first threshold value H _R1 , the heater energization control unit 40 includes all in-cylinder pressure sensors. The 26 glow plugs 38 may be energized. Further, the failure determination comparison unit 44 may compare the hysteresis ΔH of the actual waveform of the in-cylinder pressure for each cylinder calculated again by the hysteresis calculation unit 42 with each other. As a result, when any one of the hysteresis ΔH is different from the other remaining hysteresis ΔH by a predetermined value or more, the failure determination comparison unit 44 has an abnormality in the fuel supply system for the cylinder having the hysteresis ΔH that is significantly different from the other. It can be determined that there is.

  After the deposit removal process, in addition to determining whether there is an abnormality in the fuel supply system or the in-cylinder pressure sensor 26 itself, it is also possible to detect misfire and change the operating conditions.

  Such other embodiments of the present invention will be described with reference to FIGS. 5 to 7, but elements having the same functions as those of the previous embodiments are denoted by the same reference numerals, and redundant descriptions are omitted. . The control block in this embodiment is shown in FIG. The ECU 24 in this embodiment includes the above-described injection valve drive control unit 25, operation state determination unit 31, waveform calculation unit 32, heater energization control unit 40, reference waveform storage unit 41, hysteresis calculation unit 42, and drive determination comparison unit 43. In addition, a lower heating value calculation unit 47, a misfire determination unit 48, and an operation condition change unit 49 are provided.

However, the injection valve drive control unit 25 in this embodiment also outputs information related to the fuel injection amount supplied to the combustion chamber 12 to the lower heating value calculation unit 47. The heater energization control unit 40 determines that the in-cylinder pressure waveform hysteresis ΔH calculated by the waveform calculation unit 32 is greater than the (first) threshold value H _R1 , and the drive determination comparison unit 43 determines that the engine 10 In the low load operation state, the heater element of the glow plug 38 is energized.

  The low load operation state here refers to an idling state of the engine 10 or an operation state with a lighter load than this, for example, a single injection state of fuel in the previous motoring state. The single injection of fuel in the motoring state does not give a large driving force to the engine 10 and is used for detecting abnormalities of sensors, etc., but at the time of misfire determination in this embodiment, Can also be used. Whether or not the engine 10 is in the low load operation state is determined by the operation state determination unit 31.

  FIG. 6 shows the change rate of the lower heat generation amount in such a low load operation state. The two-dot chain line in FIG. 6 shows the case of a normal combustion state in which no misfire has occurred, and it can be seen that the rate of change in the lower heat generation amount changes rapidly immediately before and after the TDC. On the other hand, the solid line shows the case where misfire occurs, and it can be seen that the rate of change in the lower heat generation amount changes gently. Such a difference can be noticeable particularly when the engine 10 is in the low-load operation state described above. Therefore, it is possible to determine misfire based on the low heat generation amount in the low load operation state of the engine 10.

After the heater energization control unit 40 energizes the heater element of the glow plug 38 to perform deposit removal processing, the lower heating value calculation unit 47 calculates the lower heating value Q of the fuel supplied to the combustion chamber 12 as an in-cylinder pressure sensor. 26 and the detection signal from the crank angle sensor 30 are used for calculation. Specific theories and details regarding the calculation method of the lower heating value Q are described in Japanese Patent Application Laid-Open Nos. 2001-152952 and 2005-30332. That is, the lower heating value calculation unit 47 first raised the pressure in the combustion chamber 14 in the expansion stroke, that is, the cylinder pressure P, and the volume V of the combustion chamber 14 at the time of detection of the cylinder pressure P to a power of a predetermined index κ. The product PV ^κ with the value is calculated as a control parameter related to the instantaneous heat generation amount h when the in-cylinder pressure P is detected, that is, as a heat generation amount index.

The product of the in-cylinder pressure P and the value V ^{κ obtained} by raising the volume V of the combustion chamber 14 to the exponent κ at the time of detection of the in-cylinder pressure P (hereinafter referred to as a heat generation amount parameter) PV ^κ and the instantaneous heat generation amount The fact that h has a correlation, that is, h∽PV ^κ has been described in detail in JP-A-2005-36754 and is well known.

Next, the fuel supply amount per cycle to one cylinder set by the injection valve drive control unit 25 using the calculated heat generation amount parameter PV ^κ (hereinafter referred to as a set injection amount) τ Is calculated as a control parameter relating to the lower heating value Q that is the heating value of the true fuel, that is, the lower heating value index h / τ. The lower heating value Q is obtained by dividing the instantaneous heat generation amount h by the set injection amount τ, and can be expressed as Q∽PV ^κ / τ from the relationship of h∽PV ^κ described above.

PV ^κ / τ calculated in this way by the lower heating value calculation unit 47 is output to the misfire determination unit 48 as the lower heating value Q. Note that the method for calculating the lower heating value Q is not limited to the above-described embodiment, and other known methods can naturally be employed.

Misfire determining unit 48, a threshold Q _R based on the property of the fuel in the set set injection amount τ stored in advance in use by injector driving control unit 25 are stored, to the threshold Q _R , and compares the lower calorific value Q calculated by the lower calorific value calculation unit 47, which determines whether the threshold value Q _R above. More specifically, when lower calorific value Q calculated by the lower calorific value calculation unit 47 is less than the threshold Q _R for determining misfire, because naturally a predetermined output to be obtained is not obtained, the misfire determination section 48 determines that a misfire has occurred, and outputs the information to the operating condition changing unit 49.

  The operating condition changing unit 49 changes the operating condition of the engine 10 only when a misfire has occurred based on the determination result of the misfire determining unit 48. Specifically, control that makes it difficult to misfire, for example, correction information for advancing the fuel injection timing and correction information for increasing the fuel injection amount are output to the injection valve drive control unit 25.

  The previous injection valve drive control unit 25 corrects the fuel injection timing and the injection amount from the fuel injection valve 11 based on the correction information from the operating condition changing unit 49. Thereby, the misfire of the engine 10 is eliminated and smooth operation can be continued.

  FIG. 7 shows a control procedure in this embodiment. First, in step S31, it is determined whether or not the vehicle is in a predetermined driving state. If the driving state determination unit 31 determines that the vehicle is in the predetermined driving state, the process proceeds to step S32 to detect the in-cylinder pressure. In step S33, the detected waveform hysteresis of the in-cylinder pressure is calculated with respect to the reference waveform of the in-cylinder pressure supplied from the reference waveform storage unit 41.

Then, it is determined whether or not the waveform hysteresis ΔH calculated in step S34 is larger than the first threshold value H _R set in advance, and the calculated waveform hysteresis ΔH is equal to or less than the first threshold value H _R set in advance. In other words, when it is determined that the magnitude of the waveform hysteresis ΔH is sufficiently small, the deposit is not so much deposited and deposited on the pressure receiving portion of the in-cylinder pressure sensor 26, so the process returns to step S31 without doing anything. In contrast, the waveform hysteresis ΔH calculated is greater than a first threshold value H _R set in advance, that is attached to the pressure receiving portion of the deposit cylinder pressure sensor 26 to the extent that adversely affect the time of performing the operation control of the engine 10 If it is determined that there is a possibility of accumulation, the process proceeds to step S35 to determine again whether or not the vehicle is in the predetermined operation state, and in the predetermined operation state, in this case, the low load operation state. Only when the operation state determination unit determines that there is, the process proceeds to step S36 to energize the heater element of the glow plug 38 to remove deposits deposited and deposited on the pressure receiving unit of the in-cylinder pressure sensor 26.

At this time, a predetermined amount of fuel is injected into the combustion chamber 12 in step S37, and the lower heating value Q is calculated based on detection signals from the in-cylinder pressure sensor 26 and the crank angle sensor 30. The misfire when the calculated lower calorific value Q is determined by preset threshold Q _R greater than or equal is whether the S38 in step determines that the lower heating value Q is the threshold value Q _R or Since this has not occurred, the operation conditions are not changed and the processing is finished as it is.

If it is determined in step S38 that the lower heating value Q is smaller than the threshold value Q _R , that is, misfire has occurred, the process proceeds to step S39 and the operation condition change process is made such that misfire is less likely to occur. For example, a control for increasing the fuel injection amount or advancing the injection timing is performed.

  In this way, it is possible to more appropriately control the operating state of the engine 10 by determining the presence or absence of misfire during the deposit removal process of the in-cylinder pressure sensor 26 and changing the operating conditions as necessary. . Therefore, it is also effective to simultaneously perform the misfire determination process described above in step S18 in the embodiment shown in FIG.

  It should be noted that the present invention should be construed only from the matters described in the claims, and in the above-described embodiment, all the changes and modifications included in the concept of the present invention are other than those described. Is possible. That is, all matters in the above-described embodiment are not intended to limit the present invention, and include any configuration not directly related to the present invention. To get.

1 is a conceptual diagram of an embodiment according to the present invention. It is a control block diagram in the embodiment shown in FIG. 2 is a graph schematically showing an output waveform of a glow plug integrated cylinder pressure sensor in the embodiment shown in FIG. 1. It is a flowchart showing the control procedure in embodiment shown in FIG. It is a control block diagram in other embodiments of the present invention. 6 is a graph schematically showing a relationship between a crank angle phase and a lower heating value change rate in the embodiment shown in FIG. 5. It is a flowchart showing the control procedure in embodiment shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 11 Fuel injection valve 12 Combustion chamber 13 Exhaust passage 14 Intake passage 15 Intake port 16 Exhaust port 17 Cylinder head 18 Intake valve 19 Exhaust valve 20 Exhaust pipe 21 Oxidation catalyst 22 Intake pipe 23 Piston 24 ECU
25 Injection valve drive control unit 26 In-cylinder pressure sensor 27 Accelerator opening sensor 28 Air flow meter 29 Water temperature sensor 30 Crank angle sensor 31 Operating state determination unit 32 Waveform calculation unit 33 Accelerator pedal 34 Cylinder block 35 Water jacket 36 Connecting rod 37 Crankshaft 38 Glow plug 39 Injection valve drive control unit 40 Heater energization control unit 41 Reference waveform storage unit 42 Hysteresis calculation unit 43 Drive determination comparison unit 44 Failure determination comparison unit 45 Warning display drive control unit 46 Warning display 47 Low calorific value calculation Section 48 Misfire determination section 49 Operating condition change section

Claims (12)

A glow plug-integrated in-cylinder pressure sensor in which the pressure receiving portion of the in-cylinder pressure sensor for detecting the pressure in the combustion chamber of the internal combustion engine is constituted by a heat generating tube in which the heater element of the glow plug is housed;
When the internal combustion engine is in a predetermined operating state, a hysteresis calculating unit that calculates the hysteresis of the actual waveform of the in-cylinder pressure detected by the glow plug-integrated in-cylinder pressure sensor with respect to a preset reference waveform of the in-cylinder pressure;
A glow plug drive determination comparison unit that compares the hysteresis calculated by the hysteresis calculation unit with a preset first threshold;
A control device for an internal combustion engine, comprising: a heater energization control unit that controls energization of the heater element based on a comparison result in the glow plug drive determination comparison unit.   A sensor failure determination comparison unit that compares the hysteresis calculated again by the hysteresis calculation unit with the second threshold value set in advance after the heater energization control unit supplies power to the heater element; The control apparatus for an internal combustion engine according to claim 1, further comprising: The glow plug integrated in-cylinder pressure sensor is arranged for each cylinder of the internal combustion engine,
A fuel supply system failure determination comparing unit that compares the hysteresis of each cylinder that is recalculated by the hysteresis calculating unit after energizing the heater element by the heater energizing control unit; The control apparatus for an internal combustion engine according to claim 1 or 2, characterized by the above-mentioned. The heater energization control unit controls energization to the heater element based on the operation state of the internal combustion engine in addition to the comparison result in the glow plug drive determination comparison unit.
A lower heating value calculation unit that calculates a lower heating value of the internal combustion engine after the heater element is energized by the heater energization control unit;
The control of the internal combustion engine according to claim 1 or 2, further comprising: a misfire determination unit that determines the presence or absence of misfire based on the lower heat generation amount calculated by the lower heat generation amount calculation unit. apparatus.   5. The control apparatus for an internal combustion engine according to claim 4, further comprising an operation condition changing unit that changes an operation condition of the internal combustion engine based on a determination result in the misfire determination unit. Control of an internal combustion engine using a glow plug-integrated in-cylinder pressure sensor in which a pressure receiving portion of an in-cylinder pressure sensor for detecting a pressure in a combustion chamber of the internal combustion engine is composed of a heat generating tube in which a heater element of the glow plug is housed. A method,
Determining whether the internal combustion engine is in a predetermined operating state;
Calculating the hysteresis of the actual waveform of the in-cylinder pressure actually detected with respect to a preset reference waveform of the in-cylinder pressure when the internal combustion engine is in a predetermined operating state;
Comparing the calculated hysteresis with a first preset threshold;
A control method for an internal combustion engine, comprising: a step of controlling energization to the heater element based on the comparison result. Comparing the hysteresis initially calculated after energization of the heater element with a preset second threshold;
A step of determining whether or not the glow plug integrated sensor has failed based on the comparison result, and the step of determining whether or not the glow plug integrated sensor has failed has a preset hysteresis. The method for controlling an internal combustion engine according to claim 6, wherein if it is greater than the second threshold value, it is determined that the glow plug integrated sensor has failed. The glow plug integrated in-cylinder pressure sensor is arranged for each cylinder of the internal combustion engine,
Comparing the hysteresis for each cylinder calculated first after energizing the heater element with each other;
8. The method for controlling an internal combustion engine according to claim 6, further comprising a step of determining whether there is an abnormality in the fuel injection system based on the comparison result.   The step of determining whether or not there is an abnormality in the fuel injection system is such that when the hysteresis in any one cylinder is different from the hysteresis in the other remaining cylinders by a predetermined value or more, the fuel injection system for this one cylinder is abnormal. The method for controlling an internal combustion engine according to claim 8, wherein it is determined that the engine is present. The step of controlling energization to the heater element is performed based on the operation state of the internal combustion engine in addition to the comparison result between the calculated hysteresis and the first threshold value.
Calculating a lower heating value in the internal combustion engine after energizing the heater element;
8. The method for controlling an internal combustion engine according to claim 6, further comprising a step of determining the presence or absence of misfire based on the calculated lower heating value.   The step of controlling the energization of the heater element is characterized in that the heater element is energized when the calculated hysteresis is greater than a first threshold and the internal combustion engine is in a low load operating state. The method for controlling an internal combustion engine according to claim 8.   The method for controlling an internal combustion engine according to claim 10 or 11, further comprising a step of changing an operating condition of the internal combustion engine of the internal combustion engine based on a determination result of the presence or absence of misfire.

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