JP4474327B2 - Engine system design method and engine system designed by the design method - Google Patents

Description

  The present invention relates to an engine system design method and an engine system designed by the design method, and more particularly, to an engine system design method including a knock determination device that determines whether or not knocking has occurred, and the engine system design method. Related to the engine system.

  Conventionally, a technique for detecting knocking of an internal combustion engine is known. Japanese Patent Laying-Open No. 2001-227400 (Patent Document 1) discloses a knock control device for an internal combustion engine that can accurately determine whether or not knocking has occurred. A knock control device for an internal combustion engine described in Patent Literature 1 includes a signal detection unit that detects a vibration waveform signal generated in the internal combustion engine, and a period in which the vibration waveform signal detected by the signal detection unit is equal to or greater than a predetermined value. Is detected as an occurrence period, a peak position detection unit that detects a peak position in the occurrence period detected by the occurrence period detection unit, and occurrence of knock in the internal combustion engine based on the relationship between the occurrence period and the peak position A knock determination unit that determines presence or absence, and a knock control unit that controls the operating state of the internal combustion engine in accordance with a determination result by the knock determination unit. The knock determination unit determines that knock (knocking) has occurred when the peak position for the generation period is within a predetermined range.

According to the knock control device for an internal combustion engine described in this publication, the vibration waveform signal generated in the internal combustion engine is detected by the signal detection unit, and the generation period and the peak position where the vibration waveform signal is equal to or greater than a predetermined value. Are detected by the occurrence period detector and the peak position detector, respectively. In this way, by knowing at which position in the generation period of the vibration waveform signal the peak is generated, the knock determination unit determines whether or not knocking has occurred in the internal combustion engine, and the internal combustion engine is determined according to the knock determination result. The operating state is controlled. In the knock determination unit, when the peak position with respect to the occurrence period is within a predetermined range, that is, with a waveform shape such that the peak position appears earlier with respect to the occurrence period of the predetermined length of the vibration waveform signal. In some cases, it is recognized as unique when a knock occurs. As a result, even when the operating state of the internal combustion engine changes abruptly or when the electric load is turned on / off, the presence or absence of knocking in the internal combustion engine is accurately determined, and the operating state of the internal combustion engine can be controlled appropriately. .
JP 2001-227400 A

  By the way, Japanese Patent Laid-Open No. 2001-227400 knows in advance the peak position when knocking occurs from data obtained by actually operating the engine in order to determine whether knocking has occurred. There is a need. However, depending on the shape of the engine (internal combustion engine), even if knocking occurs, vibrations caused by knocking may not be clearly detected. For example, if the vibration caused by knocking is difficult to be transmitted to the knock sensor mounting position and the mechanical vibration of the engine itself is easily transmitted to the knock sensor mounting position, it may be difficult to specify the peak position when knocking occurs. obtain. In such a case, it is necessary to re-acquire the data by operating the engine again after changing the design to a shape that makes it easy to specify the peak position when knocking occurs. Therefore, as a result, there is a problem that man-hours required for manufacturing the engine system may increase.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an engine system design method capable of suppressing the man-hours during manufacture and an engine system designed by the method. That is.

  An engine system design method according to a first aspect of the present invention is a method of manufacturing an engine system including a knock determination device that determines whether knock has occurred. This design method applies a predetermined vibration to an engine block including a cylinder head and a cylinder block, and detects the vibration of the cylinder head and the vibration of the cylinder block, so that the transfer characteristic of vibration caused by knocking is obtained. An analysis step for analyzing, and a setting step for setting information used in the knocking determination device by operating the engine according to the analysis result of the transfer characteristic.

  According to the first aspect of the present invention, the engine block including the cylinder head and the cylinder block is given a predetermined vibration to the engine block, and the vibration of the cylinder head and the vibration of the cylinder block are detected. In an actual engine, the position of the piston at the time of knocking is in the range of about 10 ° to 60 ° after compression top dead center (ATDC), so vibration transmitted to the cylinder block in the combustion chamber is suppressed by the piston. Vibration transmission from the cylinder head (S: head portion vibration response) becomes dominant. On the other hand, when the position of the piston is lowered, the suppression of the cylinder block by the piston is released, and the cylinder block starts to resonate (N: liner portion vibration response). Therefore, the S / N ratio can be obtained in a pseudo manner with the vibration characteristics of the cylinder head as the knocking signal (S) and the vibration characteristics of the engine block as the noise signal (N). Based on this pseudo S / N ratio, the transmission characteristic of vibration caused by knocking is analyzed. For example, when the pseudo S / N ratio is small, it can be said that the transmission of vibration due to knocking is poor. Such an engine has poor controllability such as ignition timing because it is difficult to determine whether knocking has occurred due to the influence of noise (such as mechanical vibration of the engine itself). Such an engine requires a design change or the like. On the other hand, when the pseudo S / N ratio is large, it can be said that the transmission of vibration caused by knocking is good. Such an engine has a good controllability such as ignition timing because it is easy to determine whether knocking has occurred. Such an engine does not require any design changes. In accordance with such an analysis result, information used in the knocking determination device is set by operating the engine. For example, the engine is actually operated and used in the knock determination device only when it is determined that the controllability such as the ignition timing is good because the pseudo SN ratio is large and the vibration due to knocking is good. Information is set. Accordingly, it is possible to prevent the engine from being determined to have poor controllability after the engine is assembled and actually operated and information used in the knocking determination device is set. Therefore, it is possible to avoid redesigning the data by operating the engine again after changing the design. As a result, it is possible to provide a method for designing an engine system that can reduce the number of man-hours during manufacturing.

  In the engine system design method according to the second invention, in addition to the configuration of the first invention, the knock determination device determines whether or not knocking has occurred in the engine based on vibration in a preset frequency band. To do. The information is a frequency band of vibration. The setting step includes a step of setting the frequency band of vibration used in the knocking determination device to a frequency band other than the frequency band including the vibration of the cylinder block.

  According to the second aspect, the frequency band of vibration used in the knocking determination device is set to a frequency band other than the frequency band including the vibration of the cylinder block. Thereby, taking in the mechanical vibration of the cylinder block itself as vibration caused by knocking can be suppressed, and it can be accurately determined whether or not knocking has occurred.

  In the engine system design method according to the third invention, in addition to the configuration of the first invention, the knocking determination device includes a vibration waveform detected in the first operating state and a preset first waveform. The vibration waveform detected in the second operating state is corrected based on the result of comparing the two, and the intensity of vibration is determined based on the result of comparing the corrected waveform with the preset second waveform. A value is calculated, and it is determined whether or not knocking has occurred in the engine based on the result of comparing the calculated value with a preset threshold value. The threshold value is corrected according to the state of occurrence of vibration in the engine. The information is an initial value of the first waveform, the second waveform, and the threshold value. The setting step includes a step of setting the first waveform, the second waveform, and the initial value of the threshold value used in the knocking determination device by operating an engine manufactured so as to satisfy a predetermined condition. Including.

  According to the third invention, the information is an initial value of the first waveform, the second waveform, and the threshold value. The setting step is set by operating an engine manufactured so that initial values of the first waveform, the second waveform, and the threshold value used in the knocking determination device satisfy a predetermined condition. For example, the first waveform, the second waveform, and the initial value of the threshold value used in the knock determination device are operated by operating an engine manufactured such that tolerances such as dimensions and knock sensor output have a median value. Is set. Thereby, the initial values of the first waveform, the second waveform, and the threshold value used in the knocking determination device can be set without individually operating all manufactured engines. Therefore, man-hours necessary for manufacturing the engine system can be suppressed.

  In the engine system design method according to the fourth aspect of the invention, in addition to the configuration of the third aspect of the invention, the predetermined condition is that the tolerance is a median value.

  According to the fourth aspect of the invention, for example, the first waveform and the second waveform used in the knock determination device by operating an engine manufactured such that the tolerances such as the size and the output of the knock sensor have a median value. And an initial threshold value is set. Thereby, the initial values of the first waveform, the second waveform, and the threshold value used in the knocking determination device can be set without individually operating all manufactured engines. Therefore, man-hours necessary for manufacturing the engine system can be suppressed.

  An engine system according to a fifth invention is an engine system designed by the engine system design method according to any one of the first to fourth inventions.

  According to the fifth invention, it is possible to provide an engine system designed by an engine system design method capable of suppressing man-hours during manufacturing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIGS. 1 to 7, a method for analyzing a transmission characteristic of vibration caused by knocking in the engine system design method according to the embodiment of the present invention will be described.

  FIG. 1 is an overall perspective view showing the configuration of the vibration transfer characteristic analyzing apparatus 100 and the computer 200 in the present embodiment, FIG. 2 is a side view showing the structure of the vibration transfer characteristic analyzing apparatus 100, and FIG. FIG. 4 is a schematic view showing the structure of the high-precision height adjustment mechanism 120, and FIG. 4 is a schematic cross-sectional view showing the internal configuration of the engine block. 5 is an enlarged cross-sectional view of the cylinder head 162, and FIG. 6 is a view taken along line VI in FIG.

  As shown in FIGS. 1 and 2, the structure of the vibration transfer characteristic analyzing apparatus 100 in the present embodiment has an engine block 160 on which a vibration transfer characteristic is to be analyzed on a surface plate 110, and a predetermined value for the engine block 160. And a vibration exciter 130 for applying the above vibration. An anti-vibration rubber 150 is interposed between the engine block 160 and the surface plate 110 in order to block vibration from the outside. In addition, the high-accuracy height adjustment mechanism 120 is interposed between the vibration device 130 and the surface plate 110 from the viewpoint of accurately applying vibration to the engine block 160. As the vibration device 130, an electromagnetic vibration device or the like is used. Note that the external dimensions of the vibration transfer characteristic analyzing apparatus 100 in the present embodiment are about 450 mm wide, 450 mm deep, and 400 mm high.

  As shown in FIG. 2, the vibration device 130 has a support bolt 131 of the vibration device 130 in a U-shaped groove 123 provided in a holding jig 122 attached to the base 121 of the high-precision height adjustment mechanism 120. It is held and allows for a rough height adjustment. Further, as shown in FIG. 3, the high-precision height adjusting mechanism 120 includes a wedge member 121b and a wedge member 121c disposed in the case 121a of the base 121, and by rotating the handle 121d, The wedge member 121c moves in the X direction and the Y direction, and the height position can be adjusted in units of several tens of micrometers.

  As shown in FIG. 2, the engine block 160 includes a cylinder block 161 having a cylinder bore and a cylinder head 162, and the vibration shaft 140 of the vibration device 130 is attached to a knock sensor mounting boss 163 provided on the cylinder block 161. It is connected. The knock sensor mounting boss 163 is a cylindrical protrusion for mounting a knock sensor (hereinafter also referred to as a knock sensor) that detects the occurrence of knocking in an actual engine.

  Referring to FIG. 4, a cylinder block vibration detection sensor 310 as a cylinder block vibration measuring instrument is disposed at a position of the cylinder block 161 facing the knock sensor mounting boss 163 on the inner surface of the cylinder bore 161A. In an actual engine, a piston 164 that slides up and down is disposed in the cylinder bore 161A, and the position where the cylinder block vibration detection sensor 310 is disposed is disposed in a region corresponding to the combustion chamber A on the inner surface of the cylinder bore. Is done. Since the knock sensor mounting boss 163 is formed with high accuracy, the vibration shaft 140 can be mounted with high accuracy on the cylinder block 161.

  Referring to FIG. 5, a cylinder head vibration detection sensor 320 as a cylinder head vibration measuring device is disposed in a plug hole 162p provided in the cylinder head 162. The cylinder head vibration detection sensor 320 includes special bolts 301, It consists of a metal cube 302 and a sensor 303. As shown in FIG. 6, the plug hole 162p is provided in a central region of the cylinder head 162 surrounded by an intake valve hole 162i and an exhaust valve hole 162e provided in the cylinder head 162. Further, since the plug hole 162p is formed with high precision by machining, the cylinder head vibration detection sensor 320 can be attached to the cylinder head 162 with high precision.

  A vibration analysis method for the engine block 160 at the time of knocking using the vibration transfer characteristic analyzer 100 having the above-described configuration, that is, a method for analyzing the transfer characteristic of vibration caused by knocking will be described. The transfer characteristic is analyzed using an SN ratio based on a knocking signal (S: cylinder head vibration characteristic) and a noise signal (N: engine block vibration characteristic).

  First, a predetermined vibration is applied to the engine block 160 from the vibration shaft 140 connected to the knock sensor mounting boss 163 of the engine block 160 using the vibration device 130. Next, the vibration signal 1 generated in the cylinder block 161 and the vibration signal 2 generated in the cylinder head 162 are picked up using the cylinder block vibration detection sensor 310 and the cylinder head vibration detection sensor 320. The vibration signal 1 and the vibration signal 2 are input to the computer 200, and vibration transmission characteristics (S / N ratio) when the engine block 160 is knocked are analyzed.

  In the state where the assembled engine is actually operated, the position of the piston 164 when knocking occurs is in the range of about 10 ° to 60 ° after compression top dead center (ATDC) as shown in FIG. Vibration transmitted to the cylinder block 161 in A is suppressed by the piston 164, and vibration transmission from the cylinder head 162 (S: head portion vibration response) becomes dominant. On the other hand, when the position of the piston 164 is lowered, the suppression of the cylinder block 161 by the piston 164 is released, and the cylinder block 161 starts to resonate (N: liner portion vibration response).

  Therefore, a pseudo S / N ratio can be obtained by using the vibration characteristic of the cylinder head 162 as a knocking signal (S) and the vibration characteristic of the engine block 161 as a noise signal (N).

  In the vibration transfer characteristic analyzing apparatus 100 according to the present embodiment, two types of vibration measuring sensors, a cylinder block vibration measuring sensor 310 and a cylinder head vibration measuring sensor 320, are arranged in the combustion chamber A, so By picking up a response signal when a predetermined vibration is applied to the engine block 160 by the cylinder block vibration measurement sensor 310 and the cylinder head vibration measurement sensor 320, the vibration characteristics of the cylinder block 161 and the vibration characteristics of the cylinder head 162 are obtained. That is, the pseudo S / N ratio based on the knocking signal (S: vibration characteristic of the cylinder head) and the noise signal (N: vibration characteristic of the engine block) can be grasped in advance.

  Based on this pseudo S / N ratio, the transmission characteristic of vibration caused by knocking is analyzed. For example, when the pseudo S / N ratio is small, it can be said that the transmission of vibration due to knocking is poor. Such an engine has poor controllability such as ignition timing because it is difficult to determine whether knocking has occurred due to the influence of noise (such as mechanical vibration of the engine itself). Such an engine needs to be changed to a shape that facilitates transmission of vibration caused by knocking by making a design change or the like.

  On the other hand, when the pseudo S / N ratio is large, it can be said that the transmission of vibration caused by knocking is good. Such an engine has a good controllability such as ignition timing because it is easy to determine whether knocking has occurred. Such an engine does not require any design changes.

  In the present embodiment, an analysis using a pseudo S / N ratio is performed, and only when a predetermined criterion (for example, a criterion that the pseudo S / N ratio is larger than a threshold value) is satisfied, an actual engine (operable) The engine ECU (Electronic Control Unit) is adapted (optimization of information such as parameters used in the engine ECU) from the data obtained by operating the engine that is actually assembled).

  Hereinafter, a knock determination device in an engine system designed by the engine system design method according to the present embodiment will be described. The knocking determination device is realized by a program executed by engine ECU 200, for example.

  With reference to FIG. 8, engine 1000 for determining whether or not knocking has occurred by the knocking determination device will be described.

  Engine 1000 is an internal combustion engine that burns an air-fuel mixture of air sucked from air cleaner 1020 and fuel injected from injector 1040 by igniting with an ignition plug 1060 in a combustion chamber.

  When the air-fuel mixture burns, the piston 1080 is pushed down by the combustion pressure, and the crankshaft 1100 rotates. The combusted air-fuel mixture (exhaust gas) is purified by the three-way catalyst 1120 and then discharged outside the vehicle. The amount of air taken into engine 1000 is adjusted by throttle valve 1140.

  Engine 1000 is controlled by engine ECU 2000. Engine ECU 2000 is connected to knock sensor 3000, water temperature sensor 3020, crank position sensor 3060 provided opposite to timing rotor 3040, throttle opening sensor 3080, vehicle speed sensor 3100, and ignition switch 3120. ing.

  Knock sensor 3000 is composed of a piezoelectric element. Knock sensor 3000 generates a voltage due to vibration of engine 1000. The magnitude of the voltage corresponds to the magnitude of the vibration. Knock sensor 3000 transmits a signal representing a voltage to engine ECU 2000. Water temperature sensor 3020 detects the temperature of cooling water in the water jacket of engine 1000 and transmits a signal representing the detection result to engine ECU 2000.

  The timing rotor 3040 is provided on the crankshaft 1100 and rotates together with the crankshaft 1100. A plurality of protrusions are provided on the outer periphery of the timing rotor 3040 at predetermined intervals. The crank position sensor 3060 is provided to face the protrusion of the timing rotor 3040. When the timing rotor 3040 rotates, the air gap between the protrusion of the timing rotor 3040 and the crank position sensor 3060 changes, so that the magnetic flux passing through the coil portion of the clamp position sensor 3060 increases and decreases, and an electromotive force is generated in the coil portion. . Crank position sensor 3060 transmits a signal representing electromotive force to engine ECU 2000. Engine ECU 2000 detects the crank angle based on the signal transmitted from crank position sensor 3060.

  Throttle opening sensor 3080 detects the throttle opening and transmits a signal representing the detection result to engine ECU 2000. Vehicle speed sensor 3100 detects the number of rotations of a wheel (not shown) and transmits a signal representing the detection result to engine ECU 2000. Engine ECU 2000 calculates the vehicle speed from the rotational speed of the wheel. The ignition switch 3120 is turned on by the driver when the engine 1000 is started.

  Engine ECU 2000 performs arithmetic processing based on signals transmitted from each sensor and ignition switch 3120, a map and a program stored in memory 2020, and controls equipment so that engine 1000 is in a desired operating state. .

  In the present embodiment, engine ECU 2000 determines a predetermined knock detection gate (a predetermined second crank angle from a predetermined first crank angle based on a signal and a crank angle transmitted from knock sensor 3000). The vibration waveform of the engine 1000 (hereinafter referred to as a vibration waveform) is detected in the interval until the engine section 1000), and it is determined whether or not knocking has occurred in the engine 1000 based on the detected vibration waveform. The knock detection gate in the present embodiment is from top dead center (0 degree) to 90 degrees in the combustion stroke. The knock detection gate is not limited to this.

  When knocking occurs, vibration of a frequency near the frequency indicated by the solid line in FIG. That is, when knocking occurs, vibrations of frequencies included in first frequency band A, second frequency band B, third frequency band C, and fourth frequency band D are generated in engine 100. In addition, the frequency band including the frequency of the vibration resulting from knocking is not limited to four.

  Among these frequency bands, the fourth frequency band D includes the resonance frequency of the engine 100 itself, which is indicated by a one-dot chain line in FIG. Resonance frequency vibration occurs regardless of knocking. This resonance frequency is substantially the same as the vibration frequency detected by the cylinder block vibration measurement sensor 310 in the vibration transfer characteristic analyzer 100.

  Therefore, in the present embodiment, the vibration waveform is detected based on the vibration intensity (magnitude) V in the first frequency band A to the third frequency band C that does not include the resonance frequency. The number of frequency bands used for detecting the vibration waveform is not limited to three.

  The vibration intensity V is expressed by the output voltage value of knock sensor 3000. The vibration intensity V may be expressed by a value corresponding to the output voltage value of the knock sensor 300. The output voltage value of knock sensor 3000 in each of the first frequency band A to the third frequency band C (a value representing the intensity of vibration) is integrated every 5 degrees (for 5 degrees) in crank angle. Thereby, as shown in FIG. 10, the vibration waveform for every frequency band is detected. FIG. 10 shows a vibration waveform in the frequency band A. By detecting the vibration waveform by the integrated value every 5 degrees, it is possible to suppress detection of a vibration waveform having a complicated shape in which the vibration intensity changes finely.

  The vibration waveform in each frequency band is synthesized as shown in FIG. Here, the synthesis of the waveform means adding the integrated values corresponding to the respective crank angles. The synthesized waveform is compared with a knock waveform model stored in memory 2020 of engine ECU 2000, and it is determined whether or not knocking has occurred. As shown in FIG. 12, the knock waveform model is stored for each frequency band. These knock waveform models are synthesized as shown in FIG. 13 and compared with the synthesized waveform of the vibration waveform.

  In the knock waveform model, the vibration intensity is expressed as a dimensionless number from 0 to 1, and the vibration intensity does not uniquely correspond to the crank angle. That is, in the knock waveform model of the present embodiment, after the peak value of the vibration intensity, it is determined that the vibration intensity decreases as the crank angle increases. The corner is not fixed.

  The knock waveform model in the present embodiment corresponds to vibrations after the peak value of the vibration intensity generated by knocking. Note that a knock waveform model corresponding to the vibration after the rise of vibration caused by knocking may be stored.

  The knock waveform model detects the vibration waveform of engine 1000 when knocking is forcibly generated by experiments or the like, and is created and stored in advance based on the vibration waveform.

  The knock waveform model is created using engine 1000 (hereinafter referred to as a characteristic center engine) in which the dimensions of engine 1000 and the output value of knock sensor 3000 are the median of the tolerances of the dimensions and the output value of knock sensor 3000. Is done. That is, the knock waveform model is a vibration waveform when knocking is forcibly generated in the characteristic center engine. Note that the method of creating the knock waveform model is not limited to this.

  In the comparison between the vibration waveform and the knock waveform model, the normalized vibration waveform and the knock waveform model are compared. Here, normalization is to express the intensity of vibration by a dimensionless number from 0 to 1, as shown by a solid line in FIG. 14 by dividing each integrated value by the maximum integrated value. By this normalization, it is possible to compare the detected vibration waveform with the knock waveform model regardless of the vibration intensity. Therefore, it is not necessary to store a large number of knock waveform models corresponding to the vibration intensity, and the creation of the knock waveform model can be facilitated.

  By comparing the normalized vibration waveform with the knock waveform model, a correlation coefficient K, which is a value related to the deviation between the normalized vibration waveform and the knock waveform model, is calculated. As shown in FIG. 14, in a state where the timing at which the vibration intensity is maximized in the vibration waveform after normalization is matched with the timing at which the vibration intensity is maximum in the knock waveform model, The correlation coefficient K is calculated by calculating the absolute value (deviation amount) of the deviation from the knock waveform model for each crank angle (every 5 degrees).

  The absolute value of the deviation for each crank angle between the normalized vibration waveform and knock waveform model is ΔS (I) (I is a natural number), and the value obtained by integrating the vibration intensity in the knock waveform model with the crank angle (knock waveform model) If S is the area, the correlation coefficient K is calculated by the equation K = (S−ΣΔS (I)) / S. Thereby, the degree of coincidence between the detected vibration waveform and the knock waveform model can be expressed numerically and objectively determined. Here, ΣΔS (I) is the total sum of ΔS (I) from the top dead center to 90 degrees. Note that the method of calculating the correlation coefficient K is not limited to this.

  Based on the correlation coefficient K, a knock intensity N that is a value representing the intensity of vibration caused by knocking is calculated. When the maximum value of the calculated integrated value is P and a value representing the vibration intensity of the engine 1000 in a state where the engine 1000 is not knocked is BGL (Back Ground Level), the knock intensity N is N = It is calculated by the equation P × K / BGL. The knock magnitude N may be calculated based on the total sum of the integrated values instead of the maximum integrated value. Further, the calculation method of knock strength N is not limited to this.

  When knock magnitude N is larger than a predetermined determination value V (KX), it is determined that knocking has occurred, and the ignition timing is retarded. Thereby, occurrence of knocking is suppressed. On the other hand, if knock magnitude N is not greater than a predetermined determination value V (KX), it is determined that knocking has not occurred, and the ignition timing is advanced.

  Here, there are variations in dimensions in engines that are actually manufactured, and variations in the output of sensors such as the knock sensor 3000. For this reason, when the vibration waveform actually detected is directly compared with the knock waveform model, it may not be possible to accurately determine whether or not knocking has occurred.

  Further, even if the same vibration occurs in engine 1000 due to variations or deterioration in the output value of knock sensor 3000, the intensity V of the detected vibration can change. In this case, it is necessary to correct the determination value V (VK) and determine whether knocking has occurred using the determination value V (KX) corresponding to the actually detected intensity. Therefore, in the present embodiment, the vibration waveform is corrected or the determination value is corrected.

  Hereinafter, a method for correcting the vibration waveform will be described. In the memory 2020, in addition to the knock waveform model, as shown in FIG. 15, the characteristic central engine is operated in the fuel cut state (the crankshaft 1100 is rotating but the fuel supply is stopped). The vibration waveform is stored. Hereinafter, the vibration waveform of the characteristic center engine in the fuel cut state is also referred to as a hard model. In addition, you may make it memorize | store the vibration waveform at the time of cranking instead of a fuel cut state.

  In the present embodiment, the correction coefficient is calculated by dividing the integrated value of the vibration waveform detected in the fuel cut state by the integrated value in the hardware model for each crank angle (every 5 degrees). The correction coefficient calculation method is not limited to this.

  The calculated integrated value (detected vibration waveform) is corrected by multiplying this correction coefficient by the integrated value of the vibration waveform detected in an operating state (for example, during acceleration) different from the fuel cut state.

  For example, as shown in FIG. 16, when the integrated value (solid line) in the detected vibration waveform is smaller than the integrated value (broken line) in the hard model vibration waveform, the correction coefficient is calculated as a value of 1 or more. As shown in FIG. 17, the calculated integrated value (solid line) is increased to a value indicated by a broken line.

  The vibration waveform corrected in this way is compared with the knock waveform model. Thereby, variation in the intensity of vibration due to individual differences of the engine 100 can be corrected. In addition, what is necessary is just to correct | amend so that the calculated integrated value may be made small, when the integrated value in the detected vibration waveform is larger than the integrated value in a hard model.

  Hereinafter, a method for correcting the determination value V (KX) compared with the knock magnitude N will be described. In the present embodiment, as shown in FIG. 18, an intensity value LOG (V) that is a logarithmically converted intensity V for a predetermined number of ignition cycles (for example, 200 cycles) and each intensity value LOG. The determination value V (KX) is corrected using a frequency distribution indicating the relationship with the frequency (number of times, also referred to as probability) at which (V) is detected. The intensity V used for calculating the intensity value LOG (V) is a peak value of the intensity (integrated value) between predetermined crank angles.

  In the frequency distribution, a median value V (50) is calculated that accumulates the frequency of the intensity value LOG (V) from the minimum value to 50%. Further, a standard deviation σ in the frequency distribution is calculated. A value obtained by adding the product of coefficient U (U is a constant, for example, U = 3) and standard deviation σ to median value V (50) is knock determination level V (KD). The frequency of the intensity value LOG (V) greater than the knock determination level V (KD) is determined as the frequency of occurrence of knocking.

  That is, the number of magnitude values LOG (V) greater than the knock determination level V (KD) is counted as the number of times that knocking has occurred, and the ratio of magnitude values LOG (V) greater than the knock determination level V (KD) Counted as knock occupancy KC.

  Normally, knock occupancy KC is counted in this way. If knocking does not occur in engine 100, the frequency distribution is a normal distribution as shown in FIG. 19, and the maximum value V (MAX) of the intensity value LOG (V) matches the knock determination level V (KD). To do. On the other hand, when knocking occurs and the detected intensity V increases and a large intensity value LOG (V) is calculated, as shown in FIG. 20, the maximum value V is greater than the knock determination level V (KD). (MAX) increases.

  Further, when the frequency of knocking increases or the mechanical vibration of engine 100 itself increases, the maximum value V (MAX) further increases as shown in FIG. At this time, the median value V (50) and the standard deviation σ in the frequency distribution increase with the maximum value V (MAX). Therefore, knock determination level V (KD) increases.

  An intensity value LOG (V) smaller than knock determination level V (KD) is not determined to be an intensity value LOG (V) in a cycle in which knocking has occurred. Therefore, if knock determination level V (KD) increases, knocking is correspondingly increased. Even if this occurs, the frequency at which it is determined that knocking has not occurred increases.

  Therefore, when knock determination level V (KD) becomes too large, the counting method of knock occupancy KC is changed. In the count method after the change, when knock determination level V (KD) is smaller than maximum value V (MAX), maximum value V (MAX) is removed from the frequency distribution. The total sum of the frequency of the maximum value V (MAX) removed is counted as the knock occupancy KC.

  In the frequency distribution from which the maximum value V (MAX) is removed, the maximum value V (MAX) is determined again. That is, the maximum value V (MAX) in the frequency distribution is corrected to be small.

  Further, knock determination level V (KD) is calculated again in the frequency distribution after maximum value V (MAX) is determined again. That is, the knock determination level V (KD) in the frequency distribution for the intensity value LOG (V) that is less than or equal to the re-determined maximum value V (MAX) is calculated again. As long as knock determination level V (KD) is smaller than maximum value V (MAX), this process is repeated.

  When the maximum value V (MAX) is removed and the knock determination level V (KD) is recalculated, as the removed maximum value V (MAX) increases, as shown in FIG. Knock determination level V (KD) decreases as (MAX) decreases. Since the reduction rate of the maximum value V (MAX) is larger than the reduction rate of the knock determination level V (KD), there is a point where both coincide.

  As described above, the maximum value V (MAX) and the knock determination level V (KD) coincide with each other in the frequency distribution when knocking does not occur. Therefore, as shown in FIG. 23, when the maximum value V (MAX) matches the knock determination level V (KD), this knock determination level V (KD) is the frequency distribution in the case where knocking has not occurred. It can be said that the knock determination level V (KD) is simulated.

  Therefore, the frequency of the intensity value LOG (V) larger than the knock determination level V (KD) (maximum value V (MAX)) when the maximum value V (MAX) matches the knock determination level V (KD), that is, The total sum of the frequencies of the maximum values V (MAX) removed until the maximum value V (MAX) and the knock determination level V (KD) coincide with each other is counted as the knock occupancy KC (frequency of occurrence of knocking). Is done.

  When knock occupancy KC is larger than threshold value KC (0), it can be said that knocking has occurred at a frequency higher than the allowable frequency. In this case, the determination value V (KX) is decreased in order to easily determine that knocking has occurred. Accordingly, it is possible to increase the frequency at which it is determined that knocking has occurred, retard the ignition timing, and suppress the occurrence of knocking.

  On the other hand, if knock occupancy KC is smaller than threshold value KC (0), it can be said that the occurrence frequency of knocking is within an allowable value. In this case, it can be said that the output of engine 100 may be further increased.

  Therefore, the determination value V (KX) is increased. Thereby, the frequency at which it is determined that knocking has occurred can be suppressed, the ignition timing can be advanced, and the output of engine 1000 can be increased. In this way, the determination value V (KX) is corrected.

  With reference to FIG. 24, a process of manufacturing the engine system in the engine system design method according to the present embodiment will be described.

  In step (hereinafter, step is abbreviated as S) 100, the transfer characteristic of vibration caused by knocking is analyzed using the transfer characteristic analyzer 100. At this time, based on the pseudo S / N ratio obtained by using the vibration characteristic of the cylinder head 162 as the knocking signal (S) and the vibration characteristic of the engine block 161 as the noise signal (N), the transmission characteristic of vibration due to knocking is analyzed. The The analysis of the transfer characteristic is performed only on the engine block 160 without operating the engine 1000. Note that the transmission characteristics may be analyzed in a state where the piston 1080 and the crankshaft 1100 are incorporated in the engine block 160.

  In S102, the resonance frequency of cylinder block 161 is detected based on the output signal of cylinder block vibration measurement sensor 310 in transfer characteristic analyzer 100.

  In S104, it is determined whether or not the pseudo S / N ratio satisfies a predetermined criterion (for example, a criterion that the pseudo SN ratio is larger than a threshold value). If the pseudo SN ratio satisfies a predetermined criterion (YES in S104), the process proceeds to S200. If not (NO in S104), the process proceeds to S106.

  In S106, at least one of cylinder block 160 and cylinder head 161 is redesigned. Thereafter, the process returns to S100.

  In S200, when knocking is forcibly generated in a state where an actual engine (characteristic center engine) manufactured so that the tolerance of the size and the output from the knock sensor 300 is the median value is actually operated. Based on the signal from the obtained knock sensor 300, the frequency band of vibration caused by knocking is selected. At this time, a frequency band other than the frequency band including the resonance frequency of the cylinder block 161 is selected as a frequency band of vibration caused by knocking.

  In S202, a knock waveform model is set based on a signal from knock sensor 3000 obtained when knocking is forcibly generated while the characteristic central engine is actually operated.

  In S204, a hardware model is set based on a signal from knock sensor 3000 obtained when the characteristic center engine is actually operated so as to be in a fuel cut state.

  In S206, the characteristic central engine is actually operated, and an initial value of determination value V (KX) is set. The initial value of the determination value V (KX) is set to a value such that the knocking intensity and occurrence frequency in the characteristic central engine are in a desired state (ignition timing is retarded at a desired frequency).

  The operation of the engine system design method according to the present embodiment, which is expressed based on the above-described structure and flowchart, will be described.

  After the shapes of the cylinder head 160 and the cylinder block 161 are designed and before the engine ECU 2000 is adapted, first, the transfer characteristic of vibration caused by knocking is analyzed using the transfer characteristic analyzer 100 (S100). .

  In the analysis of the transfer characteristic, the pseudo S / N ratio is obtained by using the vibration characteristic of the cylinder head 160 as the knocking signal (S) and the vibration characteristic of the cylinder block 161 as the noise signal (N). Based on the magnitude of the pseudo S / N ratio, the transmission characteristic of vibration caused by knocking is analyzed.

  Further, the resonance frequency of the cylinder block 161 is measured based on the output signal of the cylinder block vibration measurement sensor 310 obtained when obtaining the pseudo S / N ratio (S102).

  Here, if the pseudo S / N ratio is small and does not satisfy a predetermined standard (NO in S104), it can be said that the transmission of vibration caused by knocking is poor. Such an engine has poor controllability such as ignition timing because it is difficult to determine whether knocking has occurred due to the influence of noise (such as mechanical vibration of the engine itself).

  Such an engine is redesigned (S106), and is changed to a shape that facilitates transmission of vibration caused by knocking. Thereby, it is possible to determine whether or not the shape of engine 1000 should be changed before adaptation of engine ECU 2000, and to prevent the adaptation result from being wasted. Therefore, reworking can be avoided and man-hours required when manufacturing the engine system can be reduced.

  On the other hand, if the pseudo S / N ratio is large and satisfies a predetermined standard (YES in S104), it can be said that the transmission of vibration caused by knocking is good. Such an engine has a good controllability such as ignition timing because it is easy to determine whether knocking has occurred. Such an engine does not require any design changes.

  In this case (YES in S104), the actual engine (characteristic central engine) manufactured so that the dimensional tolerance and the tolerance of the output from the knock sensor 3000 are the median value is actually operated to forcibly generate knocking. Based on the signal from the knock sensor 3000 obtained in the case of the selection, the frequency band of vibration caused by knocking is selected (S200). At this time, a frequency band other than the frequency band including the resonance frequency of the cylinder block 161 is selected as a frequency band of vibration caused by knocking.

  Further, a knock waveform model and a hard model are created (S202, S204) so that the knocking intensity and occurrence frequency in the characteristic center engine become a desired state (ignition timing is retarded at a desired frequency). The determination value V (KX) is set as the value.

  Although the knock waveform model and determination value V (KX) are not necessarily appropriate for all engines that are actually marketed, in the present embodiment, vibration waveform that is compared with the knock waveform model by engine ECU 2000. Or the determination value V (KX) is corrected according to the occurrence frequency of knocking.

  Therefore, when the engine ECU 2000 is adapted, it is not necessary to set the knock waveform model, the hard model, and the determination value V (KX) by operating the engine manufactured in various modes, and only the characteristic center engine is operated. The ECU 2000 can be adapted. Therefore, the number of engines to be operated in conforming to engine ECU 2000 can be suppressed, and the number of man-hours in conforming to engine ECU 2000 can be suppressed. As a result, the man-hours required for manufacturing the engine system can be suppressed.

  As described above, according to the design method of the engine system according to the present embodiment, the transmission characteristics of vibration caused by knocking are analyzed using the cylinder head and the cylinder block before assembling the engine. Only when the pseudo signal-to-noise ratio satisfies a predetermined criterion, the engine ECU is adapted by actually operating the characteristic central engine. Thereby, it is possible to determine whether or not the design change should be performed before the engine ECU is adapted, and to avoid the design change after the engine ECU is adapted. For this reason, it is possible to avoid re-adapting the engine ECU. As a result, the man-hours required for manufacturing the engine system can be suppressed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is an overall perspective view showing a configuration and a computer of a vibration transfer characteristic analyzing apparatus in an engine system manufacturing apparatus according to an embodiment of the present invention. It is a side view which shows the structure of a vibration transfer characteristic analyzer. It is a figure which shows the structure of the high precision height adjustment mechanism of a vibration transfer characteristic analyzer. It is sectional drawing which shows the internal structure of an engine block. It is sectional drawing of a cylinder head. FIG. 6 is a view taken along line VI in FIG. 5. It is a figure which shows the vibration which arises in a cylinder block, and the vibration which arises in a cylinder head. It is a schematic block diagram which shows an engine. It is a figure which shows the frequency of the vibration detected at the time of knocking generation | occurrence | production. It is a figure which shows the vibration waveform before a synthesis | combination. It is a figure which shows the vibration waveform after a synthesis | combination. It is a figure which shows the knock waveform model memorize | stored in memory of engine ECU. It is a figure which shows the knock waveform model after a synthesis | combination. It is a figure which shows the state which compared the vibration waveform after normalization, and a knock waveform model. It is a figure which shows the vibration waveform of the characteristic center engine in a fuel cut state. It is a figure which shows the state which compared the vibration waveform of the characteristic center engine, and the detected vibration waveform. It is a figure which shows the vibration waveform before and behind correction | amendment. It is a figure which shows frequency distribution of intensity value LOG (V). It is a figure which shows frequency distribution of intensity value LOG (V) in case knocking has not occurred. It is FIG. (1) which shows frequency distribution of intensity value LOG (V) when knocking occurs. FIG. 11 is a second diagram illustrating a frequency distribution of intensity values LOG (V) when knocking occurs. It is a figure which shows transition of the maximum value V (MAX) and knock determination level V (KD) in frequency distribution. It is a figure which shows frequency distribution of the state in which the maximum value V (MAX) and the knock determination level V (KD) corresponded. It is a flowchart which shows the process in which an engine system is manufactured in the design method of the engine system which concerns on this Embodiment.

Explanation of symbols

100 vibration transfer characteristic analyzer, 110 surface plate, 120 high-precision height adjustment mechanism, 121
Base, 121a Case, 121b, 121c Wedge member, 121d Handle, 122 Holding jig, 123 U-shaped groove, 130 Excitation device, 131 Support bolt, 140 Excitation shaft, 141 Excitation bolt, 145 Excitation rod, 146 Attachment, 146h Shaft hole, 146s Screw hole, 146b Fixing screw, 150 Anti-vibration rubber, 161 Cylinder block, 161A Cylinder bore, 161h Screw hole, 160 Engine block, 162 Cylinder head, 162e Exhaust valve hole, 162i Intake valve hole, 162p Plug Hole, 163 Knock sensor mounting boss, 164 Piston, 200 Computer, 301 Special bolt, 302 Metal cube, 303 Sensor, 305A Male thread, 305B Female thread, 310 Cylinder block vibration detection sensor, 320 Cylinder head Vibration detection sensor, 1000 engine, 1040 injector, 1060 spark plug, 1100 crankshaft, 1160 intake valve, 1180 exhaust valve, 1200 pump, 2000 engine ECU, 3000 knock sensor, 3020 water temperature sensor, 3040 timing rotor, 3060 crank position sensor, 3080 Throttle opening sensor.

Claims (4)

A design method for an engine system including a knocking determination device that determines whether knocking has occurred based on vibration in a preset frequency band ,
Giving vibration to an engine block and a cylinder head and a cylinder block, by detecting the vibration of the vibration and the cylinder block of the cylinder head, the vibration characteristics of the cylinder head and knocking signals, vibration characteristics of the engine block An analysis step for determining whether or not the obtained pseudo S / N ratio is larger than a threshold ,
If the pseudo SN ratio is larger than the threshold value, the frequency of vibration forcibly operating the engine to generate knocking, the frequency band of vibration to be used in the knock determination device, due to knocking A setting step of setting to a frequency band other than the frequency band including the resonance frequency of the cylinder block among the included frequency bands . Based on the result of comparison between the vibration waveform detected in the fuel cut state and the preset first waveform, the vibration waveform detected in the operation state different from the fuel cut state is corrected, and the correction is performed. Based on the result of comparing the measured waveform and the preset second waveform, a value related to the intensity of vibration is calculated, and based on the result of comparing the calculated value with a preset threshold value , a design method of an engine system including a knock determination device for determining whether Roh Kkingu occurs,
By applying vibration to an engine block including a cylinder head and a cylinder block and detecting the vibration of the cylinder head and the vibration of the cylinder block, the vibration characteristic of the cylinder head is made a knocking signal, and the vibration characteristic of the engine block An analysis step for determining whether or not the obtained pseudo S / N ratio is larger than a threshold,
When the pseudo signal-to-noise ratio is larger than the threshold value, the first waveform is set based on a signal from a knock sensor when the engine is operated so as to be in a fuel cut state, and knocking is forcibly performed. on the basis of the signal from the knock sensor in the case of operating the engine to generate including setting step of setting the second waveform, et emissions gin system design methods. The engine system design method according to claim 2 , wherein the engine used in the setting step is manufactured so as to satisfy a condition that a tolerance is a median value. Engine system designed by the design method for an engine system according to any of claims 1-3.

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