Apparatus and method for determining engine knocking

Abstract

To improve knocking determination accuracy in knocking determination device and method for an engine.SOLUTION: An auxiliary chamber type engine in which a flame of an auxiliary chamber is jetted out to a main chamber for combustion includes: a pressure amplitude acquisition section that acquires pressure amplitude of the main chamber; a region partition section that partitions the pressure amplitude acquired by the pressure amplitude acquisition section into a first region up to a cylinder pressure maximum value and a second region after the cylinder pressure maximum value; and a determination section that determines occurrence of knocking by comparing first maximum amplitude of the pressure amplitude in the first region with second maximum amplitude of the pressure amplitude in the second region.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an apparatus and method for determining engine knocking. [Background technology]

[0002] In engines where combustion occurs through flame propagation, the pressure and temperature of unburned gases increase as combustion progresses, and combustion due to self-ignition before flame propagation, known as knocking, can occur. Knocking generates pressure waves in the combustion chamber, which can damage components of the combustion chamber, such as the piston. On the other hand, advancing the ignition timing is effective in improving the thermal efficiency of the engine. However, advancing the ignition timing makes knocking more likely to occur, and there is a limit to how far the ignition timing can be advanced. Therefore, it is extremely important to accurately determine the occurrence of knocking in an engine.

[0003] A conventional knocking determination device for an engine is, for example, that described in Patent Document 1. The knocking determination device described in Patent Document 1 evaluates the pressure amplitude (in-cylinder pressure) after filtering the detected in-cylinder pressure, and determines that knocking has occurred when the pressure amplitude reaches or exceeds a predetermined value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-205386 Summary of the Invention [Problem to be solved by the invention]

[0005] A pre-chamber gas engine is known, which has an ignition pre-chamber in the cylinder head. In a pre-chamber engine, a fuel-air mixture is supplied to the main combustion chamber, and fuel is also supplied to the pre-chamber. When the mixture in the main combustion chamber is compressed by the piston, the fuel in the pre-chamber is ignited by a spark plug, and a flame is ejected into the main combustion chamber, igniting the mixture in the main combustion chamber and propagating the flame. In such a pre-chamber gas engine, when the flame in the pre-chamber is ejected into the main combustion chamber, a pressure wave is generated by the torch jet. Therefore, when determining the occurrence of knocking based on the magnitude of the pressure amplitude, the pressure wave due to the torch jet ejection acts as noise and affects the pressure amplitude, which may result in an erroneous determination of the occurrence of knocking.

[0006] The present disclosure is intended to solve the above-mentioned problems, and aims to provide an engine knocking determination device and method that improves the accuracy of knocking determination. [Means for solving the problem]

[0007] In order to achieve the above object, the engine knocking determination device of the present disclosure is provided in an auxiliary chamber engine in which flame in an auxiliary chamber is ejected into a main chamber for combustion, and includes: a pressure amplitude acquisition unit that acquires the pressure amplitude of the main chamber; a region division unit that divides the pressure amplitude acquired by the pressure amplitude acquisition unit into a first region up to a maximum internal cylinder pressure value and a second region after the maximum internal cylinder pressure value; and a determination unit that compares a first maximum amplitude of the pressure amplitude in the first region with a second maximum amplitude of the pressure amplitude in the second region to determine the occurrence of knocking.

[0008] Furthermore, the disclosed method for determining engine knocking in an auxiliary chamber engine in which flame in an auxiliary chamber is ejected into a main chamber for combustion includes the steps of: acquiring the pressure amplitude of the main chamber; dividing the acquired pressure amplitude into a first region up to a maximum in-cylinder pressure value and a second region after the maximum in-cylinder pressure value; and comparing a first maximum amplitude of the pressure amplitude in the first region with a second maximum amplitude of the pressure amplitude in the second region to determine the occurrence of knocking. [Effects of the Invention]

[0009] According to the engine knocking determination device and method disclosed herein, it is possible to improve the accuracy of knocking determination. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the internal configuration of a pre-chamber gas engine. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of the engine knocking determination device according to the first embodiment. [Figure 3] FIG. 3 is a graph showing the in-cylinder pressure versus the crank angle. [Figure 4] FIG. 4 is a flowchart showing a method for determining engine knocking. [Figure 5] FIG. 5 is a schematic diagram showing the configuration of an engine knocking determination device according to the second embodiment. [Figure 6] FIG. 6 is a graph showing the in-cylinder pressure versus the crank angle. [Figure 7] FIG. 7 is a flowchart showing a method for determining engine knocking. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

[0012] [First embodiment] <Pre-chamber gas engine> FIG. 1 is a schematic diagram showing the internal configuration of a pre-chamber gas engine.

[0013] As shown in Figure 1, the engine of the first embodiment is a pre-chamber gas engine 10. In the first embodiment, the engine is a pre-chamber gas engine 10, but other types of engines may be used as long as they have a main chamber and a pre-chamber. The pre-chamber gas engine 10 includes a cylinder block 11, a cylinder head 12, and a piston 13.

[0014] The cylinder block 11 is block-shaped and has a cylindrical space extending in the vertical direction, into which a cylinder liner 21 is attached. Although not shown, a plurality of spaces are provided at intervals in the horizontal direction of the cylinder block 11. The cylinder head 12 is disposed on top of the cylinder block 11 and is fastened to the cylinder block 11 with a plurality of bolts (not shown).

[0015] The piston 13 has a cylindrical shape and is disposed within a cylinder liner 21 of the cylinder block 11, where it is supported so as to be freely movable in the axial direction. Although not shown, a crankshaft is rotatably supported at the bottom of the cylinder block 11, and the piston 14 and the crankshaft are connected via a connecting rod.

[0016] The main combustion chamber (main chamber) 22 is a space defined by the inner circumferential surface of the cylinder liner 21 in the cylinder block 11, the lower surface of the cylinder head 12, and the top surface of the piston 13. The main combustion chamber 22 is connected to the ends of an intake port 23 and an exhaust port 24 provided in the cylinder head 12. The lower end of an intake valve 25 is disposed in the intake port 23, and the lower end of an exhaust valve 26 is disposed in the exhaust port 24. The intake valve 25 and the exhaust valve 26 are supported by the cylinder head 12 so as to be freely movable along the axial direction, and are biased by a biasing member (not shown) in a direction (upward in FIG. 1 ) that closes the intake port 23 and the exhaust port 24. The intake valve 25 and the exhaust valve 26 open the intake port 23 and the exhaust port 24 by the action of an intake cam and an exhaust cam (not shown), and a mixture of fuel gas and air is supplied to the main combustion chamber 22.

[0017] An auxiliary combustion chamber nozzle 31 is attached to the underside of the cylinder head 12, facing upward from the main combustion chamber 22. The auxiliary combustion chamber nozzle 31 is located in the radial center of the main combustion chamber 22 and protrudes toward the main combustion chamber 22. The auxiliary combustion chamber nozzle 31 has an auxiliary combustion chamber (auxiliary chamber) 32 provided inside, and has multiple injection ports 33 formed at intervals in the circumferential direction on the protruding part toward the main combustion chamber 22. The auxiliary combustion chamber 32 communicates with the main combustion chamber 22 via the multiple injection ports 33.

[0018] Additionally, an auxiliary chamber holder 34 is attached to the cylinder head 12 above the auxiliary chamber nozzle 31. The auxiliary chamber holder 34 is cylindrical and has an auxiliary chamber gas valve 35 disposed therein. The auxiliary chamber gas valve 35 opens during the intake stroke to supply fuel gas to the auxiliary combustion chamber 32. An ignition plug 36 is attached to the cylinder head 12 between the auxiliary chamber nozzle 31 and the auxiliary chamber holder 34. The spark plug 36 can ignite the fuel-containing mixture supplied to the auxiliary combustion chamber 32.

[0019] The pre-chamber gas engine 10 performs four strokes (intake stroke, compression stroke, expansion stroke, and exhaust stroke) during two revolutions of the crankshaft. During this time, the intake camshaft and exhaust camshaft rotate once, and the intake valve 25 and exhaust valve 26 open and close the intake port 23 and exhaust port 24. When an air-fuel mixture is supplied to the main combustion chamber 22 from the intake port 23, the mixture is compressed as the piston 13 rises.

[0020] Meanwhile, the pre-combustion chamber gas valve 35 supplies fuel gas to the pre-combustion chamber 32. Then, the spark plug 36 ignites the fuel gas supplied to the pre-combustion chamber 32. The fuel gas then burns in the pre-combustion chamber 32, generating combustion gas. The combustion gas in the pre-combustion chamber 32 is ejected as a torch from multiple injection ports 33 into the main combustion chamber 22. The air-fuel mixture compressed in the main combustion chamber 22 is combusted by the torch from the pre-combustion chamber 32. The piston 13 is pushed down by the explosion load generated by this combustion, causing the crankshaft to rotate. The combustion gas generated in the main combustion chamber 22 is discharged from the exhaust port 24 as exhaust gas.

[0021] <Knocking detection device> FIG. 2 is a schematic diagram showing the configuration of the engine knocking determination device according to the first embodiment.

[0022] As shown in FIG. 2, a crank angle sensor 41 and an in-cylinder pressure sensor 42 are connected to the knocking determination device 40. The crank angle sensor 41 detects the rotation angle (phase of 360 degrees) of the crankshaft and outputs it to the knocking determination device 40. That is, the crank angle sensor 41 detects the rotation angle of the crankshaft with top dead center as a reference. For example, a disk with slits spaced apart in the circumferential direction is fixed to the crankshaft, and the rotating disk is detected by an optical sensor, an electromagnetic sensor, or the like, and the crank position (rotation angle) is output. The in-cylinder pressure sensor 42 detects the pressure in the main combustion chamber 22 (see FIG. 1) (hereinafter, referred to as in-cylinder pressure) and outputs it to the knocking determination device 40. The in-cylinder pressure sensor 42 is, for example, a piezoelectric high-temperature pressure sensor attached to the cylinder head.

[0023] The knocking determination device 40 is also connected to the engine control unit 43. The knocking determination device 40 outputs the knocking determination result, i.e., whether or not knocking has occurred in the pre-chamber gas engine 10, to the engine control unit 43. The engine control unit 43 controls the timing of advance of the pre-chamber gas engine 10 according to the knocking determination result.

[0024] Here, the knocking determination device 40 and the engine control unit 43 are control devices. The control devices as the knocking determination device 40 and the engine control unit 43 are controllers, and are realized by, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) executing various programs stored in a storage unit using a RAM as a work area. Note that the knocking determination device 40 and the engine control unit 43 may be configured as a single control device.

[0025] The knocking determination device 40 includes a filter processing unit (pressure amplitude acquisition unit) 51, an area partitioning unit 52, a first maximum amplitude calculation unit 53, a second maximum amplitude calculation unit 54, and a determination unit 55.

[0026] The filter processing unit 51 is a band-pass filter that uses a certain frequency to remove low-frequency and high-frequency components from the in-cylinder pressure detected by the in-cylinder pressure sensor 42, thereby determining the pressure amplitude of a specific frequency. That is, the filter processing unit 51 obtains the temporal change in the pressure amplitude of the main combustion chamber 22 relative to the crank angle (time).

[0027] The region dividing unit 52 divides the change in pressure amplitude in the main combustion chamber 22 with respect to the crank angle acquired by the filter processing unit 51 into a first region and a second region. Here, the first region is a time region up to the maximum in-cylinder pressure, and the second region is a time region after the maximum in-cylinder pressure. The start time of the first region is, for example, before the start of combustion, and the end time of the second region is after the end of combustion. In other words, the first region is the period from before the start of combustion until the in-cylinder pressure reaches its maximum in-cylinder pressure, and the second region is the period from when the in-cylinder pressure reaches its maximum in-cylinder pressure until the end of combustion.

[0028] The first maximum amplitude calculation unit 53 calculates the first maximum amplitude from the change in pressure amplitude in the first region. That is, the first maximum amplitude calculation unit 53 calculates the difference between the maximum in-cylinder pressure and the minimum in-cylinder pressure when the maximum amplitude is reached in the first region as the first maximum amplitude. The second maximum amplitude calculation unit 54 calculates the second maximum amplitude from the change in pressure amplitude in the second region. That is, the second maximum amplitude calculation unit 54 calculates the difference between the maximum in-cylinder pressure and the minimum in-cylinder pressure when the maximum amplitude is reached in the second region as the second maximum amplitude. Note that the amplitude here refers to the difference between adjacent peaks and valleys (or valleys) of the pressure waveform. However, in addition to such differences, the amplitude also includes, for example, the differences between the pressure at the boundary between the first region and the second region and the peaks or valleys before and after it.

[0029] The determination unit 55 determines whether knocking has occurred by comparing the first maximum amplitude in the first region with the second maximum amplitude in the second region. That is, the determination unit 55 determines that knocking has occurred when the ratio of the second maximum amplitude to the first maximum amplitude exceeds a preset ratio determination value.

[0030] <Knocking detection method> FIG. 3 is a graph showing the in-cylinder pressure versus crank angle, and FIG. 4 is a flowchart showing a method for determining engine knocking.

[0031] The method for determining knocking in an engine of the first embodiment includes the steps of acquiring the pressure amplitude of the main combustion chamber 22, dividing the acquired pressure amplitude into a first region up to the maximum in-cylinder pressure value and a second region after the maximum in-cylinder pressure value, and comparing a first maximum amplitude of the pressure amplitude in the first region with a second maximum amplitude of the pressure amplitude in the second region to determine the occurrence of knocking.

[0032] In FIG. 3, the solid line in the upper part represents the in-cylinder pressure detected by the in-cylinder pressure sensor 42, and the solid line in the lower part represents the pressure amplitude of the main combustion chamber after the filtering process 51 processes the in-cylinder pressure.

[0033] The in-cylinder pressure reaches its maximum in-cylinder pressure value Pmax at time (crank angle) tpmax. Therefore, the first region TW1 defined by the region defining unit 52 is the period from before combustion starts to time tpmax, and the second region TW2 is the period from time tpmax to after combustion ends. In other words, by defining the first region TW1 and the second region TW2 based on the time when the in-cylinder pressure reaches its maximum in-cylinder pressure Pmax, the pressure amplitude in the first region TW1 becomes a vibration that does not include the influence of knocking, and in the second region, if knocking occurs, becomes a vibration that is influenced by knocking.

[0034] In the first region, the minimum in-cylinder pressure Pt1-max occurs when the first maximum amplitude P1 occurs at time (crank angle) t1-max, and the maximum in-cylinder pressure Pt1+max occurs when the first maximum amplitude P1 occurs at time (crank angle) t1+max. Therefore, in the first region, the first maximum amplitude calculation unit 53 calculates the first maximum amplitude P1 by subtracting the minimum in-cylinder pressure Pt1-max from the maximum in-cylinder pressure Pt1+max.

[0035] Furthermore, in the second region, the maximum in-cylinder pressure Pt2+max occurs when the second maximum amplitude P2 occurs at time (crank angle) t2+max, and the minimum in-cylinder pressure Pt2-max occurs when the second maximum amplitude P2 occurs at time (crank angle) t2-max. Therefore, in the second region, the second maximum amplitude calculation unit 54 calculates the second maximum amplitude P2 by subtracting the minimum in-cylinder pressure Pt2-max from the maximum in-cylinder pressure Pt2+max.

[0036] The determination unit 55 compares the first maximum amplitude P1 in the first region TW1 with the second maximum amplitude P2 in the second region TW2 to determine whether knocking has occurred. That is, the determination unit 55 determines that knocking has occurred when the ratio P2 / P1 between the first maximum amplitude P1 and the second maximum amplitude P2 exceeds a ratio determination value Pj. That is, the determination unit 55 determines that knocking has occurred when the second maximum amplitude P2 in the second region becomes excessively large.

[0037] 2 and 4, in step S11, the knocking determination device 40 takes in the in-cylinder pressure detected by the in-cylinder pressure sensor 42. In step S12, the filter processing unit 51 filters the in-cylinder pressure to calculate the pressure amplitude in the main combustion chamber 22 with respect to the crank angle (time).

[0038] In step S13, the region dividing unit 52 divides a first region TW1 and a second region TW2 using the time (crank angle) tpmax at which the in-cylinder pressure reaches the maximum value Pmax as a boundary. In step S14, the first maximum amplitude calculating unit 53 calculates the first maximum amplitude P1 by subtracting the minimum in-cylinder pressure Pt1-max at which the first maximum amplitude P1 is achieved from the maximum in-cylinder pressure Pt1+max at which the first maximum amplitude P1 is achieved in the first region. In step S15, the second maximum amplitude calculating unit 54 calculates the second maximum amplitude P2 by subtracting the minimum in-cylinder pressure Pt2-max at which the second maximum amplitude P2 is achieved from the maximum in-cylinder pressure Pt2+max at which the second maximum amplitude P2 is achieved in the second region.

[0039] Then, in step S16, the determination unit 55 compares the first maximum amplitude P1 in the first region TW1 with the second maximum amplitude P2 in the second region TW2 to determine whether knocking has occurred. That is, the determination unit 55 determines whether the ratio P2 / P1 of the second maximum amplitude P2 to the first maximum amplitude P1 exceeds a ratio determination value Pj (e.g., 1.3). If the determination unit 55 determines that the ratio P2 / P1 of the second maximum amplitude P2 to the first maximum amplitude P1 exceeds the ratio determination value Pj (Yes), the determination unit 55 determines that knocking has occurred in step S17. On the other hand, if the determination unit 55 determines that the ratio P2 / P1 of the second maximum amplitude P2 to the first maximum amplitude P1 does not exceed the ratio determination value Pj (No), the determination unit 55 determines that knocking has not occurred in step S18.

[0040] [Second embodiment] 5 is a schematic diagram showing the configuration of an engine knocking determination device according to a second embodiment. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals and detailed descriptions thereof will be omitted.

[0041] As shown in Figure 1, in the pre-combustion chamber gas engine 10, combustion gas from the pre-combustion chamber 32 is ejected into the main combustion chamber 22 as a spark, causing the compressed air-fuel mixture to burn in the main combustion chamber 22. At this time, the air-fuel mixture may self-ignite in the main combustion chamber 22 before the flame spreads, resulting in knocking. In this case, knocking may occur before the in-cylinder pressure reaches its maximum value. In the second embodiment, when it is estimated that knocking will occur early, the periods of the first and second regions are corrected to prevent erroneous determination of knocking.

[0042] As shown in FIG. 5, the knocking determination device 40A includes a filter processing unit 51, an area partitioning unit 52, a first maximum amplitude calculation unit 53, a second maximum amplitude calculation unit 54, a determination unit 55, a time difference calculation unit 61, an erroneous determination evaluation unit 63, and an area correction unit 64.

[0043] The time difference calculation unit 61 calculates the time difference between the time when the maximum in-cylinder pressure is reached in the first region and the time when the maximum in-cylinder pressure is reached in the second region, that is, the time difference.

[0044] When the determination unit 55 determines that knocking has not occurred and determines that the absolute value of the time difference is shorter than the time difference determination value, the erroneous determination evaluation unit 63 evaluates that the determination that knocking has not occurred may be erroneous. At this time, the area correction unit 64 corrects the first area and the second area.

[0045] In this case, the error judgment evaluation unit 63 sets the time difference judgment value to 1 / 2 to 1 of the time difference between the maximum in-cylinder pressure and the minimum in-cylinder pressure when the pressure amplitude is maximum in the combined first and second regions. That is, the time difference judgment value is a specified value ranging from 1 / 2 to 1 of the absolute value obtained by subtracting the time of the minimum in-cylinder pressure from the time of the maximum in-cylinder pressure. In other words, the time difference judgment value is 1 / 4 to 1 / 2 cycle of the pressure.

[0046] The region correction unit 64 then corrects the boundary position between the first region and the second region without changing the width of each section based on the time difference judgment value (a specified value from 1 / 4 to 1 / 2 cycle of the pressure waveform). Note that the region correction unit 64 preferably shifts the boundary position between the first region and the second region toward the first region by the time difference judgment value (a specified value from 1 / 4 to 1 / 2 cycle of the pressure waveform), but is not limited to this method. The region correction unit 64 may simply shift the boundary position between the first region and the second region toward the first region by between 1 / 4 cycle of the pressure waveform and 1 / 2 cycle of the pressure waveform.

[0047] After the area correction unit 64 corrects the first area and the second area, the processing of the first maximum amplitude calculation unit 53, the second maximum amplitude calculation unit 54, and the determination unit 55 is executed again.

[0048] FIG. 6 is a graph showing the in-cylinder pressure and heat release rate versus crank angle, and FIG. 7 is a flowchart showing a method for determining engine knocking.

[0049] In Figure 6, the solid line in the upper row represents the in-cylinder pressure detected by the in-cylinder pressure sensor 42, the solid line in the middle row represents the heat release rate in the main combustion chamber calculated from the in-cylinder pressure, and the solid line in the lower row represents the pressure in the main combustion chamber obtained by processing the in-cylinder pressure by the filter processing unit 51.

[0050] Since the in-cylinder pressure reaches its maximum value Pmax at time (crank angle) tpmax, the first region TW1 defined by the region defining section 52 is the period from before combustion starts to time tpmax, and the second region TW2 is the period from time tpmax to after combustion ends.

[0051] If knocking occurs early, the maximum in-cylinder pressure Pt1+max in the first region TW1 and the maximum in-cylinder pressure Pt2+max in the second region TW2 will be the same. Therefore, the time difference calculation unit 61 calculates the absolute value (|tp2max+tp1+max|) of the time difference between the time tp1+max at which the maximum in-cylinder pressure Pt1+max in the first region is reached and the time tp2+max at which the maximum in-cylinder pressure in the second region is reached, i.e., the time difference tm.

[0052] When the determination unit 55 determines that knocking has not occurred and determines that the time difference tm is shorter than the time difference determination value tmj, the error determination evaluation unit 63 evaluates that the determination that knocking has not occurred may be erroneous. That is, if the time difference calculation unit 61 determines that the time tp1+max at which the maximum in-cylinder pressure Pt1+max in the first region is reached is the same as the time tp2+max at which the maximum in-cylinder pressure Pt2+max in the second region is reached, the time difference tm=0. Therefore, the error determination evaluation unit 63 determines that the time difference tm is shorter than the time difference determination value tmj and evaluates that the determination that knocking has not occurred may be erroneous.

[0053] In this case, the error judgment evaluation unit 63 sets the time difference judgment value tmj to 1 / 2 to 1 of the time difference twm between the maximum in-cylinder pressure Pt+max and the minimum in-cylinder pressure Pt-max when the pressure amplitude is maximum in the combined region of the first region TW1 and the second region TW2. Then, the region correction unit 64 shifts the boundary position between the first region and the second region toward the first region TW1 by the time difference judgment value tmj (a specified value from 1 / 4 cycle to 1 / 2 cycle of the pressure), as shown by the dashed-dotted line in FIG.

[0054] A method for determining whether knocking has occurred will be specifically described below. As shown in Figures 2 and 7, the processes from step S11 to step S17 are the same as those in the first embodiment.

[0055] If the determination unit 55 determines in step S16 that the ratio P2 / P1 of the second maximum amplitude P2 to the first maximum amplitude P1 does not exceed the ratio determination value Pj (No), then the determination unit 55 determines in step S18 that knocking has not occurred. However, there is a possibility that the determination that knocking has not occurred is erroneous. Therefore, in step S21, the time difference calculation unit 61 calculates the absolute value of the time difference between the time tp1+max at which the maximum in-cylinder pressure Pt1+max in the first region is reached and the time tp2+max at which the maximum in-cylinder pressure Pt2+max in the second region is reached, that is, the time difference tm.

[0056] In step S22, the error determination evaluation unit 63 determines whether the time difference tm is shorter than the time difference determination value tmj. If the error determination evaluation unit 63 determines that the time difference tm is not shorter than the time difference determination value tmj (No), the determination of the occurrence of knocking is deemed correct and the routine is terminated. On the other hand, if the error determination evaluation unit 63 determines that the time difference tm is shorter than the time difference determination value tmj (Yes), the determination of the occurrence of knocking is deemed incorrect and the routine proceeds to step S23. Then, in step S23, the region correction unit 64 shifts the boundary position between the first region and the second region toward the first region TW1 by the time difference determination value tmj (a specified value from ¼ cycle to ½ cycle of the pressure amplitude) without changing the widths of the respective sections of the first region and the second region.

[0057] In step S23, when the area correction unit 64 corrects the first area and the second area, the process returns to step S14, and the processes from step S14 onward are repeatedly executed.

[0058] [Effects of this embodiment] The engine knocking determination device according to the first aspect is provided in an auxiliary combustion chamber gas engine 10 in which flame from an auxiliary combustion chamber (auxiliary chamber) 32 is ejected into a main combustion chamber (main chamber) 22 for combustion, and includes a filter processing unit (pressure amplitude acquisition unit) 51 that acquires the pressure amplitude of the main combustion chamber 22, a region division unit 52 that divides the pressure amplitude acquired by the filter processing unit 51 into a first region up to the maximum in-cylinder pressure and a second region after the maximum in-cylinder pressure, and a determination unit 55 that compares the first maximum amplitude of the pressure amplitude in the first region with the second maximum amplitude of the pressure amplitude in the second region to determine the occurrence of knocking.

[0059] According to the engine knocking determination device of the first aspect, the region dividing unit 52 divides the region into a first region and a second region, with the time when the in-cylinder pressure reaches its maximum in-cylinder pressure as the boundary. The pressure amplitude in the first region is vibration that does not include the influence of knocking, and in the second region, if knocking occurs, is vibration that includes the influence of knocking. The determination unit 55 compares the first maximum amplitude of the pressure amplitude in the first region with the second maximum amplitude of the pressure amplitude in the second region, thereby eliminating the influence of the torch jet in the first region and the second region and appropriately determining the occurrence of knocking. As a result, the accuracy of knocking determination can be improved.

[0060] In the engine knocking determination device according to the second aspect, the determination unit 55 determines that knocking has occurred when the ratio between the first maximum amplitude and the second maximum amplitude exceeds a preset ratio determination value, thereby making it possible to easily determine the occurrence of knocking.

[0061] A knocking determination device for an engine according to a third aspect includes a region correction unit 64 that corrects the first region and the second region when the ratio of the first maximum amplitude to the second maximum amplitude in the first region or the second region is equal to or less than an amplitude determination value and when the time difference between the time at which the maximum in-cylinder pressure is reached in the first region and the time at which the maximum in-cylinder pressure is reached in the second region is shorter than a preset time difference determination value. As a result, even in an engine operating state in which knocking occurs early, the region correction unit 64 corrects the first region and the second region, thereby making it possible to determine the occurrence of knocking with high accuracy.

[0062] In the engine knocking determination device according to the fourth aspect, the time difference determination value is set to half the time difference between the maximum in-cylinder pressure and the minimum in-cylinder pressure when the pressure amplitude is maximum in the combined region of the first and second regions, thereby making it possible to appropriately determine the occurrence of knocking.

[0063] In the engine knocking determination device according to the fifth aspect, the region corrector 64 corrects the boundary position between the first region and the second region based on the time difference determination value, which is equivalent to a quarter cycle of the pressure waveform in the pressure amplitude. This allows the first region and the second region to be appropriately corrected.

[0064] A knocking determination method for an engine according to a sixth aspect includes the steps of acquiring a pressure amplitude in the main combustion chamber 22, dividing the acquired pressure amplitude into a first region up to the maximum in-cylinder pressure and a second region after the maximum in-cylinder pressure, and determining the occurrence of knocking by comparing a first maximum amplitude of the pressure amplitude in the first region with a second maximum amplitude of the pressure amplitude in the second region. The pressure amplitude in the first region is vibration that does not include the influence of knocking, and the pressure amplitude in the second region is vibration that includes the influence of knocking if knocking occurs. By comparing the first maximum amplitude of the pressure amplitude in the first region with the second maximum amplitude of the pressure amplitude in the second region, the determination unit 55 can appropriately determine the occurrence of knocking while eliminating the influence of the torch jet in the first region and the second region. As a result, the accuracy of knocking determination can be improved. [Explanation of symbols]

[0065] 10. Pre-chamber gas engine 11 Cylinder block 12 Cylinder head 13 Piston 21 Cylinder liner 22 Main combustion chamber (main chamber) 23 Intake port 24 exhaust port 25 Intake valve 26 Exhaust valve 31 Antechamber cap 32 Pre-combustion chamber (pre-chamber) 33 Nozzle 34 Antechamber Holder 35 Sub-chamber gas valve 36 Spark plug 40,40A Knocking detection device 41 Crank angle sensor 42 Cylinder pressure sensor 43 Engine control unit 51 Filter processing unit (pressure amplitude acquisition unit) 52 Area division 53 1st maximum amplitude calculation section 54 Second maximum amplitude calculation section 55 Judgment section 61 Time difference calculation unit 63 False positive evaluation unit 64 Area correction section

Claims

1. In a pre-chamber engine, the flame in the pre-chamber is ejected into the main chamber for combustion. a pressure amplitude acquisition unit that acquires a pressure amplitude of the main chamber; a region dividing unit dividing the pressure amplitude acquired by the pressure amplitude acquiring unit into a first region up to a maximum in-cylinder pressure and a second region after the maximum in-cylinder pressure; a determination unit that compares a first maximum amplitude of the pressure amplitude in the first region with a second maximum amplitude of the pressure amplitude in the second region, and determines that knocking has occurred when a ratio between the first maximum amplitude and the second maximum amplitude exceeds a predetermined ratio determination value; a region correction unit that corrects the first region and the second region when a ratio between the first maximum amplitude and the second maximum amplitude in the first region or the second region is equal to or less than the ratio determination value and a time difference between a time when the maximum in-cylinder pressure in the first region is reached and a time when the maximum in-cylinder pressure in the second region is reached is shorter than a predetermined time difference determination value; An engine knocking determination device comprising:

2. the time difference determination value is set as half of a time difference between a maximum in-cylinder pressure and a minimum in-cylinder pressure when the pressure amplitude is maximized in a region including the first region and the second region. The engine knocking determination device according to claim 1.

3. the region correction unit corrects the boundary position between the first region and the second region based on the time difference determination value, based on a time difference equivalent to a quarter cycle of a pressure waveform in the pressure amplitude.

3. The engine knocking determination device according to claim 1 or 2.

4. In a pre-chamber engine, the flame in the pre-chamber is ejected into the main chamber for combustion. acquiring a pressure amplitude of the main chamber; dividing the acquired pressure amplitude into a first region up to a maximum in-cylinder pressure value and a second region after the maximum in-cylinder pressure value; comparing a first maximum amplitude of the pressure amplitude in the first region with a second maximum amplitude of the pressure amplitude in the second region, and determining that knocking has occurred when a ratio between the first maximum amplitude and the second maximum amplitude exceeds a predetermined ratio determination value; correcting the first region and the second region when a time difference between a time when the maximum in-cylinder pressure is reached in the first region and a time when the maximum in-cylinder pressure is reached in the second region is shorter than a predetermined time difference judgment value when a ratio between the first maximum amplitude and the second maximum amplitude in the first region or the second region is equal to or less than the ratio judgment value; A method for determining knocking in an engine having the above-mentioned features.

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