JP2007092620A - Knocking condition judgment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a knocking condition judgment device for an internal combustion engine appropriately performing knocking judgment when fuel is changed over from high octane number fuel to low octane number fuel and engine appropriately performing knocking judgment in another cylinder when timing retarding correction is performed in another cylinder with interlocking with one cylinder. <P>SOLUTION: This knocking condition judgment device 100 is provided with a sensor 28 outputting waveform signal corresponding to a knocking condition of an internal combustion engine 11, a knocking detection means 80 comparing vibration intensity of waveform of each combustion output by the sensor and a threshold value L and detecting knocking when the vibration intensity exceeds the threshold value, and a knocking condition judgment means 200 judging existence of knocking condition of the internal combustion engine 11 based on vibration intensity distribution of waveform output by the sensor 28 at predetermined combustion number of times N, and keeps the threshold value without increasing the same if number of times of knocking is smaller than a predetermined value when the knocking condition judgment means judges that knocking condition does not exist. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a knock generation state determination apparatus for an internal combustion engine that determines a knock generation state.

  In general, in an internal combustion engine, a knock sensor for detecting knock vibration is attached to the cylinder block of the internal combustion engine, and a knock frequency component is extracted from the output signal of the knock sensor for each combustion by a band pass filter, and the knock frequency component for each combustion is extracted. The peak value is compared with a knock determination threshold value to perform knock determination.

  Patent Document 1 discloses a knock occurrence state determination method that is separate from the above-described knock determination method. And in patent document 1, the threshold value for knock determination is corrected for every predetermined number of combustion based on the result of the knock occurrence state determination apparatus.

  Because of such a configuration, in Patent Document 1, it is determined that no knock has occurred by the knock occurrence state determination method even if an erroneous delay occurs due to an initial matching error in the threshold for knock determination. In this case, the knock determination threshold value can be appropriately corrected.

FIG. 9A is a diagram showing the relationship between the ignition timing (horizontal axis) and torque (vertical axis) in the prior art device as disclosed in Patent Document 1. FIG. As shown in FIG. 9 (a), in the prior art device, even when the ignition timing is shifted to the excessive knock side or the erroneous delay side, the ignition timing at which the knocking starts is generated. It is possible to accurately adjust to the vicinity (control target value). For this reason, in the internal combustion engine of patent document 1, robustness improves compared with the case where a knock generation state determination method is not used (for example, refer patent document 1).
Japanese Patent Application No. 2004-121865

  However, the occurrence of knocking varies depending on the type of fuel used in the engine. In FIG. 9B, which shows another relationship between the ignition timing and the torque, knock generation ignition timing when using a low octane fuel, for example, regular gasoline, and knock generation ignition when using a high octane fuel, for example, high-octane gasoline, are used. Each time is shown.

  As shown in the figure, the knock generation ignition timing when the low octane number fuel is used is located on the more advanced side than the knock generation ignition timing when the high octane number fuel is used. For example, at the base ignition timing (MBT), it is determined that there is knocking if low-octane fuel is used, but it may be determined that there is no knocking if high-octane fuel is used.

  Therefore, if it is determined that there is no knock when using high-octane fuel, and the threshold for knock determination is increased, if it is later replaced with low-octane fuel, knock determination will occur even though knock has actually occurred. There may be situations where you cannot.

  Further, when knocking occurs, the output of the knock sensor differs depending on the plurality of cylinders of the internal combustion engine. For this reason, it is preferable to set the knock determination threshold value independently for each of the plurality of cylinders. However, since it is necessary to suppress the difference in ignition timing between cylinders from becoming excessively large, in reality, when knocking is detected in a certain cylinder and retarded control is performed, there are also other cylinders. A certain degree of retardation control is performed in conjunction.

  In such a case, knock determination is made only in the cylinder where knock is likely to occur, and knock determination is hardly performed in the cylinder where knock is unlikely to occur. When knocking is determined and retarded in a cylinder that is likely to cause knocking, the other cylinders are also retarded in conjunction with the cylinder. For this reason, in a cylinder in which knock is unlikely to occur, knock may not always be detected. As a result, if it is determined that there is no knock occurrence in a cylinder where knock is unlikely to occur and the threshold for knock determination is increased, even if a knock occurs in a cylinder where knock is unlikely to occur, knock determination will occur in that cylinder. It can be a situation that is not done.

  The present invention has been made in view of such circumstances, and when the high-octane fuel is replaced with the low-octane fuel, knock determination is appropriately performed, and the retardation of the other cylinders is linked to one cylinder. It is an object of the present invention to provide a knock occurrence state determination device in which knock determination is appropriately performed in other cylinders when correction is performed.

  In order to achieve the above-described object, according to the first invention, in the knock generation state determination device for determining the knock generation state of the internal combustion engine, a sensor that outputs a signal having a waveform corresponding to the knock state of the internal combustion engine; A knock detection means for detecting a knock when the vibration intensity exceeds the threshold by comparing the vibration intensity of the waveform for each combustion output by the sensor with the threshold, and the knock detected by the knock detection means Counting means for counting the number of times of combustion over a predetermined number of combustion times, and a knock generation state determination means for determining the presence or absence of a knock generation state of the internal combustion engine based on the vibration intensity distribution of the waveform output by the sensor at the predetermined number of combustion times And when the knock occurrence state determining means determines that there is no knock occurrence state, the knock detection means detects the knock occurrence state. When the number of knocks is equal to or greater than a predetermined value, the threshold is increased by a predetermined correction amount, and detected by the knock detection unit when the knock generation state determination unit determines that there is no knock generation state. When the number of knocks is smaller than a predetermined value, a knock occurrence state determination device is provided that maintains the threshold value.

  That is, in the first invention, even when the knock occurrence state determination means determines that there is no knock occurrence state, the increase determination of the knock determination threshold is prohibited when the number of knocks is smaller than a predetermined value. I have to. For this reason, for example, if the above event occurs when switching from a high octane fuel to a low octane fuel, the threshold for knock determination is maintained without being increased. Nevertheless, it is possible to prevent the knock determination from becoming impossible.

  According to a second aspect of the invention, there is provided a knock generation state determination device for determining a knock generation state of an internal combustion engine having a plurality of cylinders, wherein the sensor outputs a signal having a waveform corresponding to the knock state of the internal combustion engine, and the sensor Comparing the vibration intensity of the waveform for each combustion output by the threshold with a threshold, and detecting the knock when the vibration intensity exceeds the threshold; and the waveform output by the sensor at a predetermined number of combustion times A knock occurrence state determining means for determining a knock occurrence state of the internal combustion engine based on a vibration intensity distribution of the engine, wherein no knock occurrence state is detected by the knock occurrence state determining means in one of the plurality of cylinders. When the determination is made, the remaining cylinders of the plurality of cylinders are determined to have no knock generation state by the knock generation state determination means. In this case, the threshold value for the one cylinder is increased by a predetermined correction amount, and the plurality of cylinders when the knock occurrence state determining means determines that there is no knock occurrence state in one of the plurality of cylinders. When the knock occurrence state determination means determines that the knock occurrence state exists in the remaining cylinders of the cylinders, a knock occurrence state determination device is provided that maintains the threshold value for the one cylinder. The

  That is, in the second aspect of the invention, even when it is determined that there is no knock occurrence state in one of the plurality of cylinders, if it is determined that there is a knock occurrence state in the remaining cylinders, The threshold value increase correction is prohibited. For this reason, the threshold for knock determination is maintained without being increased even in the cylinder determined to have no knock occurrence state by performing retardation correction of the other cylinders in conjunction with one cylinder, and thus the cylinder concerned. Even if knocking occurs in the cylinder, it is possible to prevent the cylinder from being knocked.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following drawings, the same members are denoted by the same reference numerals. In order to facilitate understanding, the scales of these drawings are appropriately changed.
Based on FIG. 1, a schematic configuration of an entire engine control system including a knock occurrence state determination device according to the present invention will be described. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 for detecting the intake air amount is provided downstream of the air cleaner 13. On the downstream side of the air flow meter 14, a throttle valve 15 whose opening is adjusted by the motor 10 and a throttle opening sensor 16 for detecting the throttle opening are provided.

  Further, a surge tank 17 is provided on the downstream side of the throttle valve 15, and an intake manifold 19 for introducing air into a plurality of the engine 11, for example, each of the four cylinders 1 to 4, is provided in the surge tank 17. A fuel injection valve 20 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 19 of each cylinder. A spark plug 21 is attached to each cylinder of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each spark plug 21.

  On the other hand, the exhaust pipe 22 of the engine 11 is provided with a catalyst 23 such as a three-way catalyst that purifies CO, HC, NOx, etc. in the exhaust gas, and detects the air-fuel ratio of the exhaust gas upstream of the catalyst 23. An air-fuel ratio sensor 24 is provided. In addition, the cylinder block of the engine 11 includes a coolant temperature sensor 25 that detects a coolant temperature, a knock sensor 28 that detects knock vibration, and a crank that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank. An angle sensor 26 is attached. Based on the output signal of the crank angle sensor 26, the crank angle and the engine speed are detected. Instead of the knock sensor 28, an in-cylinder pressure sensor (not shown) may be used.

  Outputs of these various sensors are input to an engine control unit 27 (hereinafter referred to as “ECU 27”). The ECU 27 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), thereby allowing the fuel injection amount of the fuel injection valve 20 and the ignition timing of the spark plug 21 to be executed. To control. The RAM built in the ECU 27 is used for storing data when executing each program and various predetermined values.

  This ECU 27 determines the presence or absence of a knock occurrence state by executing various programs for determining the knock occurrence state described later. In the engine 11 of the present invention, knock detection is performed for each combustion using the knock sensor 28. FIG. 2 is a diagram showing a flowchart of a program for performing knock detection. In step 81 of the knock determination method 80 shown in FIG. 2, the knock sensor 28 is used to detect the vibration intensity M, specifically the peak value, of the knock frequency component. Next, the vibration intensity M is compared with a predetermined detection level L (step 82). The detection level L is a value determined in advance by experiments or the like, and may be referred to as a knock determination threshold. Note that a product obtained by multiplying a separately calculated shape correlation coefficient for knock determination by the detection level L may be compared with the vibration intensity M.

  If it is determined that the vibration intensity M is greater than the detection level L, it is determined that knock has occurred in the combustion (step 84), and a process of increasing the counter number Nk of the knock detection counter by one is performed. (Step 85). If it is determined that there is a knock, the ignition timing is retarded to suppress the knock.

  On the other hand, if it is not determined that the vibration intensity M is greater than the detection level L, it is determined in step 83 that there is no knock and the process ends. If the determination of no knocking is made continuously, the ignition timing is corrected to advance, thereby improving the engine output and fuel consumption by advancing the ignition timing within the allowable range of knocking sound. ing.

  Thus, in the present invention, knock detection by the knock determination method 80 is performed for each combustion. Since the engine 11 of the present invention includes four cylinders, the first cylinder 1 to the fourth cylinder 4, such knock detection is performed for each cylinder.

  On the other hand, in the knock occurrence state determination apparatus based on the first embodiment of the present invention, the counter number Nk obtained by the knock determination method 80 is used. FIG. 3 is a diagram showing a flowchart of the control program 100 by the knock occurrence state judging apparatus according to the present invention. Since the engine 11 of the present invention has four cylinders of the first cylinder 1 to the fourth cylinder 4, one of these four cylinders is selected in step 101 of the program 100, and the selected cylinder is selected. The processing described later is performed.

  Next, in step 102 of the program 100, a process of incrementing the counter number N recorded in the combustion number counter provided in the ECU 27 by one is performed. Accordingly, the steps after step 102 are performed for each combustion of the internal combustion engine. It is assumed that the combustion number counter, the counter described later, and the knock detection counter are all incorporated in the ECU 27.

  In the present invention, the knock occurrence state determination method 200 is adopted in which the vibration intensity over a predetermined number of combustion times is statistically determined to determine the “knock occurrence state”. For this reason, in step 103, it is determined whether or not the number of combustions updated in step 102 exceeds a predetermined number, and if it exceeds, the result of the knock occurrence state determination method 200 is used. If the number of combustions does not exceed the predetermined number, the process ends.

Here, the knock occurrence state determination method 200 according to the present invention will be described.
4 and 5 are flowcharts showing a program for determining the knock occurrence state. In the knock occurrence state determination method 200, after performing the process of incrementing the counter number N recorded in the combustion number counter by one (step 201), the average value of the vibration intensity M calculated in advance in steps 202 and 203 is obtained. Update Vav and distributed Xdiv. Specifically, these update operations are performed based on the following formulas (1) and (2) using smoothing constants α and β (0 <α, β <1). In step 204, the standard deviation σ is calculated based on the following equation (3). Since the combustion number counter is updated in step 102 of the program 100, the update of the combustion number counter in step 201 is actually omitted.
Vav ← α × vibration intensity + (1−α) × Vav (1)
Xdiv ← β × (vibration intensity−Vav) ² + (1−β) × Xdiv (2)
σ ← (Xdiv) ^0.5 (3)

  By the way, FIG. 6 is a figure for demonstrating the area | region used by the knock generation state determination method. In the typical vibration intensity distribution shown in FIG. 6, in addition to the average value Vav and the standard deviation σ, three regions ZA, a region ZC, and a region ZD are shown. As illustrated, the region ZA is a region larger than “Vav + σ”, and the region ZD is a region smaller than “Vav−σ”. Further, the region ZC is a region located between “Vav−σ” and “Vav”.

  The reason why such area division is performed will be described with reference to FIG. FIG. 7A is a diagram for explaining a knock occurrence state determination method. FIG. 7A shows a state in which the knock intensity increases from the vibration intensity distribution D1 to the vibration intensity distribution D4. As can be seen from FIG. 7A, when the knock intensity increases from the vibration intensity distribution D1 to the vibration intensity distribution D4, the vibration intensity distribution extends in the right direction, that is, the direction in which the peak increases. As a result, the average value Vav also shifts in the direction of increasing, and the standard deviation σ increases. As a result, when the knock intensity increases, for example, as shown in the vibration intensity distribution D3, most of the vibration intensity distribution is included in the region ZC.

  Therefore, in the knock occurrence state determination method of the present invention, the ratio ZD / ZC between the region ZC and the region ZD is calculated for each of the vibration intensity distribution D1 from the vibration intensity distribution D1, and the knock is generated through the ratio ZD / ZC. The presence or absence of a state is determined. In this regard, in the knock occurrence state determination method 200, instead of the area ratio, the number of times the detection level L is exceeded in each of the areas ZA, ZC, ZD, that is, the counter values Na, Nc, Nd and the counter values Nd, Nc The ratio Nd / Nc is used.

  FIG. 7B shows the relationship between the knocked state, the counter value ratio Nd / Nc, and the counter value Na. As shown in FIG. 7B, the ratio Nd / Nc is relatively large in the state where no knock has occurred, and gradually decreases as knock occurs and its strength increases. As shown in the figure, when the knock strength further increases and the so-called “small knock” state is reached, the ratio Nd / Nc takes a constant value (generally zero), and the knock strength increases more than “small knock”. Even if “divergence knock” occurs, the ratio Nd / Nc does not change. In other words, the ratio Nd / Nc is effective for determining the presence or absence of a knock occurrence state in a region where the knock intensity is smaller than “small knock”.

  On the other hand, when attention is paid to the area ZA in FIG. 7A, the vibration intensity distribution in the area ZA decreases as the knock intensity increases. Accordingly, as shown in FIG. 7B, the counter value Na in the region ZA also decreases as the knock strength increases. This counter value takes a constant value in the “small knock” state. Then, in the vibration intensity distribution D4 at the time of “divergence knock”, the vibration intensity distribution is distorted and the standard deviation σ is increased, but the distortion of the vibration intensity distribution is more than that, and as shown in FIG. The counter value Na increases again. Therefore, the counter value Na can determine whether or not the “divergence knock” occurrence state exists.

  With reference to the above description, the knock occurrence state determination in the knock occurrence state determination method 200 will be described with reference to FIG. 4 again. In Step 205 to Step 207 of FIG. 4, the case division into the area ZA, the area ZC, and the area ZD shown in FIG. 7A is performed. That is, in step 205, the vibration strength M in the region ZD is selected through determination of whether or not the vibration strength M is smaller than “Vav−σ”. In step 206, the vibration strength M is “Vav−σ” or more. The vibration intensity M in the region ZC is selected through determination of whether or not it is smaller than “Vav”. Similarly, in step 207, the vibration intensity M in the region ZA is selected through determination of whether or not the vibration intensity M is larger than “Vav + σ”. Next, in each of Step 208 to Step 210, a process of incrementing the counter values Nd, Nc, Na related to the areas ZD, ZC, ZA by one is performed.

  Next, at step 211 in FIG. 5, it is determined whether or not the counter value of the combustion number counter has exceeded a predetermined number. Then, when the predetermined number of times is exceeded, the knock occurrence state is determined by the knock occurrence state determination method. Since step 104 of the program 100 exists, step 211 may be omitted.

  First, in step 212, the ratio Nd / Nc is compared with a predetermined value related to the ratio Nd / Nc. If it is determined that the ratio Nd / Nc is not smaller than the predetermined value, it is determined in step 214 that there is no knock occurrence state. (See FIG. 7 (b)). On the other hand, if it is determined that the ratio Nd / Nc is smaller than the predetermined value, it is determined that a knock has occurred, and the process proceeds to step 213.

  In step 213, it is determined whether the knock occurrence state is “small knock” or “divergence knock”. If the counter value Na is smaller than a predetermined value related to the counter value Na, it is determined in step 215 that the knock occurrence state is “small knock”. On the other hand, if the counter value Na is not smaller than the predetermined value, it is determined in step 216 that the knock occurrence state is “divergence knock”. Thereafter, in step 217, the counter values N, Na, Nc, and Nd are reset, and the processing of the knock occurrence state determination method 200 ends. As described above, in the knock occurrence state determination method 200, by using the ratio Nd / Nc and the counter value Na, it is possible to distinguish and determine the no knock state, the small knock state, and the divergent knock state.

  Here, referring to FIG. 3 again, after determining the knock occurrence state by the knock occurrence state determination method 200, it is determined in step 104 whether or not there is a knock occurrence state. Specifically, when it is determined in steps 215 and 216 of the knock occurrence state determination method 200 that “small knock” or “divergence knock”, it is determined in step 104 of the program 100 that there is a knock occurrence state.

  If it is determined that there is a knocking occurrence state, the process proceeds to step 106 where correction is performed to reduce the detection level L by a predetermined correction amount ΔL. This makes it easy to detect the subsequent knock by the knock determination method 80 described later.

  On the other hand, if it is determined in step 104 that there is a knock occurrence state, the process proceeds to step 105. In step 105, it is determined whether or not the knock detection counter value Nk obtained from step 85 of the knock determination method 80 is equal to or greater than a predetermined value Nk1 related to the knock detection counter value Nk. Here, it is assumed that the predetermined value Nk1 is obtained in advance by experiments or the like and incorporated in the ECU 27.

  If the knock detection counter value Nk is equal to or greater than the predetermined value Nk1, correction is performed in step 107 to increase the detection level L by a predetermined correction amount ΔL. This makes it difficult to detect the subsequent knock by the knock determination method 80 described later. In the drawing, the absolute values of the correction amounts ΔL in step 106 and step 107 are equal to each other, but different correction amounts may be employed in each step.

  On the other hand, if the knock detection counter value Nk is not equal to or greater than the predetermined value Nk1, the routine proceeds to step 108. At this time, the detection level L is maintained, and correction using the correction amount ΔL is not performed. In other words, in the first embodiment, when the knock detection counter value Nk is not equal to or greater than the predetermined value Nk1, the correction of the detection level L is prohibited from increasing. Next, the routine proceeds to step 109, where the combustion number counter, knock detection counter, etc. are reset and the processing is terminated.

  Thus, in the first embodiment of the present invention, even when it is determined that there is no knock occurrence state by the knock occurrence state determination method 200, the threshold for knock determination is changed based on the knock detection counter value Nk. It is decided whether to do or not. That is, in the first embodiment, the detection level L is increased only when the knock detection counter value Nk is equal to or greater than the predetermined value Nk1.

  For example, if a high-octane fuel is replaced with a low-octane fuel and the detection level is increased based on the determination that there is a knock occurrence, there will be a problem that knock determination will not be possible even though knock has actually occurred. sell. However, in the first embodiment of the present invention, since the detection level L is not corrected when the knock detection counter value Nk is not equal to or greater than the predetermined value Nk1, the above-described problems can be suppressed. It has become. Therefore, in the first embodiment, even when the high-octane fuel is replaced with the low-octane fuel, the knock determination threshold can be appropriately corrected.

  In the first embodiment, after the process for one of the first cylinder 1 to the fourth cylinder 4 is completed, the process for the other cylinder is performed. Accordingly, at this time, in step 101 of the program 100, a cylinder different from the cylinder for which the processing by the program 100 has already been completed is selected. Thereafter, the same processing as described above is repeatedly performed for all the remaining cylinders 2 to 4.

  FIG. 8 is a diagram showing a flowchart of a control program by the knock occurrence state judging device according to the second embodiment of the present invention. Steps 401 to 403, 200, and 404 of the program 400 shown in FIG. 8 are the same as steps 101 to 103, 200, and 104 in the program 100, and thus description thereof is omitted. However, in the second embodiment, it is necessary to determine the knock occurrence state for all of the cylinders 1 to 4 of the engine 11. In this regard, it should be noted that step 401 of program 400 and step 101 of program 100 are actually different.

  If it is determined in step 404 in the second embodiment that there is a knock occurrence state, the process proceeds to step 406 and correction is performed to decrease the detection level L by a predetermined correction amount ΔL. This makes it easy to detect the subsequent knock by the knock determination method 80 described later.

  On the other hand, if it is determined in step 404 that there is no knock occurrence state, the process proceeds to step 405. In step 405, it is determined whether or not there is no knock occurrence state based on the knock occurrence state determination method 200 in all of the cylinders different from the cylinder for which knock is currently determined. Specifically, when the first cylinder 1 is determined in the engine 11 having four cylinders, it is determined whether or not there is a knock occurrence state in all of the second cylinder 4 to the fourth cylinder 4. The

  If it is determined that there is no knock occurrence state in all of the second cylinder 2 to the fourth cylinder 4, the process proceeds to step 407, and correction for increasing the detection level L by a predetermined correction amount ΔL is performed. Do. This makes it difficult to detect the subsequent knock by the knock determination method 80 described later. As in the first embodiment, the correction amount ΔL in step 406 and step 407 may be different from each other.

  On the other hand, when it is not determined that the knock generation state is absent in the second cylinder 2 to the fourth cylinder 4, that is, when it is determined that all of the second cylinder 2 to the fourth cylinder 4 are in the knock generation state. Go to step 408. At this time, the detection level L is maintained, and correction using the correction amount ΔL is not performed. In other words, in the second embodiment, when it is not determined that the knock occurrence state is absent in the second cylinder 4 to the fourth cylinder 4, the increase correction of the detection level L is prohibited. Next, the routine proceeds to step 409, where the determination result regarding the first cylinder, that is, the presence or absence of the knock occurrence state in the first cylinder 1 is stored in the ROM of the ECU 27, and the process is terminated.

  Thereafter, in the second embodiment, after the processing for one of the first cylinder 1 to the fourth cylinder 4 (in this case, the first cylinder 1) is completed, the processing for the other cylinders is performed. Do. Accordingly, at this time, in step 401 of the program 400, a cylinder different from the cylinder for which the processing by the program 400 has already been completed is selected. Thereafter, the same processing as described above is performed for all the remaining cylinders 2 to 4. At this time, it is assumed that the presence / absence of the knock generation state of the other cylinder stored in step 409 is appropriately used.

  Thus, in the second embodiment of the present invention, even if it is determined that there is no knock generation state by the knock generation state determination method 200, the knock determination is based on the presence or absence of the knock generation state of other cylinders. Whether to change the threshold value for use is determined. In other words, in the second embodiment, the detection level L is increased only when all of the second cylinder 4 to the fourth cylinder 4 are not knocked.

  As described above, when the retard control is performed in a certain cylinder, a certain degree of retard control is also performed in conjunction with another cylinder, for example, the first cylinder 1. Accordingly, if it is determined that there is no knock occurrence state in the first cylinder 1, the detection level is increased based on the determination that there is a knock occurrence state. There may be a problem that the knock determination is not made in the cylinder 1. However, in the second embodiment, since the detection level L is not corrected when knocking is occurring in all of the other cylinders 2 to 4, the above-described problems are suppressed. It is possible. Therefore, in the second embodiment, it is possible to appropriately correct the knock determination threshold even when retarding the other cylinders in conjunction with one cylinder.

  In step 405 of the program 400, it is determined whether or not all the remaining cylinders 2 to 4 are in a knocking state. However, it may be determined whether or not half of all the remaining cylinders 2 to 4 have no knock occurrence state. In the embodiment described with reference to FIG. 1 and the like, the engine 11 is assumed to include four cylinders 1 to 4, but it is obvious that the number of cylinders of the engine 11 may be different. I will.

  Further, in the present invention, a method different from the knock occurrence state determination method 200 is used as long as it is a knock occurrence state determination method that statistically determines the vibration intensity over a predetermined number of combustion times and determines the presence or absence of the “knock occurrence state”. It can also be adopted. As a matter of course, the first and second embodiments may be used in combination.

It is a schematic block diagram of the whole engine control system containing the knock generation state determination apparatus based on this invention. It is a figure which shows the flowchart of the program which performs a knock detection. It is a figure which shows the flowchart of the control program by the knock generation state determination apparatus based on 1st embodiment of this invention. It is a figure which shows the flowchart of the program which performs the determination of a knock generation state. It is a figure which shows the flowchart of the program which performs the determination of a knock generation state. It is a figure for demonstrating the area | region used by the knock generation state determination method. (A) It is a figure for demonstrating the knock generation state determination method. (B) It is a figure which shows the relationship between knock state, ratio Nd / Nc of counter value, and counter value Na. It is a figure which shows the flowchart of the control program by the knock generation state determination apparatus based on 2nd embodiment of this invention. (A) It is a figure which shows the relationship between the ignition timing and torque in the apparatus of a prior art. (B) It is another figure which shows the relationship between ignition timing and a torque.

Explanation of symbols

1-4 cylinder 11 engine 12 intake pipe 13 air cleaner 14 air flow meter 15 throttle valve 16 throttle opening sensor 17 surge tank 19 intake manifold 20 fuel injection valve 21 spark plug 22 exhaust pipe 23 catalyst 24 air-fuel ratio sensor 25 cooling water temperature sensor 26 crank Angle sensor 27 Engine control unit 28 Knock sensor 80 Knock determination method 100 Control program (knock occurrence state determination device of the first embodiment)
200 Knock Generation State Determination Method 400 Control Program (Knock Generation State Determination Device of Second Embodiment)
L Detection level (threshold)
N Counter value Nk Knock detection counter value ΔL Correction amount

Claims (2)

In the knock generation state determination device (100) for determining the knock generation state of the internal combustion engine (11),
A sensor (28) that outputs a signal having a waveform corresponding to a knock state of the internal combustion engine (11), and a vibration intensity of the waveform for each combustion output by the sensor (28) and a threshold value (L) are compared. Knock detecting means (80) for detecting knock when the vibration intensity exceeds the threshold (L);
Counting means for counting the number of knocks (Nk) detected by the knock detection means over a predetermined number of combustion times;
A knock occurrence state determining means (200) for determining the presence or absence of a knock occurrence state of the internal combustion engine (11) based on a vibration intensity distribution of a waveform output by the sensor (28) at a predetermined number of combustion times (N). And
If the number of knocks (Nk) counted by the counting means is greater than or equal to a predetermined value when the knock occurrence state determination means (200) determines that there is no knock occurrence state, the threshold (L) is set. Increase by a predetermined correction amount,
If the number of knocks (Nk) counted by the counting means is smaller than a predetermined value when the knock occurrence state determining means (200) determines that there is no knock occurrence state, the threshold (L) is set. A knock occurrence state determination device that is maintained. In a knock occurrence state determination device (400) for determining a knock occurrence state of an internal combustion engine (11) having a plurality of cylinders,
A sensor (28) that outputs a signal having a waveform corresponding to a knock state of the internal combustion engine (11), and a vibration intensity of the waveform for each combustion output by the sensor (28) and a threshold value (L) are compared. Knock detecting means (80) for detecting knock when the vibration intensity exceeds the threshold (L);
Knock generation state determination means (200) for determining a knock generation state of the internal combustion engine (11) based on the vibration intensity distribution of the waveform output by the sensor (28) at a predetermined number of combustion times (N);
When one of the plurality of cylinders determines that there is no knock generation state by the knock generation state determination unit (200), the knock generation state determination unit (200) in the remaining cylinders of the plurality of cylinders. ), The threshold value (L) for the one cylinder is increased by a predetermined correction amount.
When one of the plurality of cylinders determines that there is no knock generation state by the knock generation state determination unit (200), the knock generation state determination unit (200) in the remaining cylinders of the plurality of cylinders. ), The knock occurrence state determination device is configured to maintain the threshold value (L) relating to the one cylinder.

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