JP7198093B2 - INTERNAL COMBUSTION ENGINE CONTROL DEVICE, INTERNAL COMBUSTION ENGINE SYSTEM, AND INTERNAL COMBUSTION SYSTEM CONTROL METHOD - Google Patents

Description

This disclosure relates to an internal combustion engine control device, an internal combustion engine system, and a control method for an internal combustion engine system, and in particular, detects vibration acceleration caused by combustion in a cylinder detected by an acceleration sensor that detects vibration acceleration of the internal combustion engine. The present invention relates to an internal combustion engine control device, an internal combustion engine system, and a control method for an internal combustion engine system suitable for identifying fuel ignition timing.

Conventionally, an acceleration sensor that detects vibrational acceleration is attached to the cylinder block of an internal combustion engine, and the crank angle is determined when the integrated value obtained by integrating the vibrational acceleration detected by the acceleration sensor over a specific interval exceeds the ignition timing determination level. A control device for an internal combustion engine that determines actual ignition timing is known (see, for example, Patent Document 1).

JP 2010-203342 A

As in Patent Document 1, in a configuration in which a single acceleration sensor for a specific cylinder detects the vibrational acceleration caused by combustion in that cylinder, the value of the vibrational acceleration detected by the acceleration sensor corresponds to the excitation force of combustion. Since it is affected by the inherent frequency characteristics and the structural damping characteristics of the portion where the acceleration sensor is attached, there is a fear that accurate detection cannot be performed when the combustion mode of the internal combustion engine changes.

For example, when the combustion form (combustion mode) is changed from a normal combustion mode to a combustion mode with a long combustion period, the center frequency of combustion shifts to the low frequency side. At this time, if an attempt is made to detect vibrational acceleration caused by internal combustion engine combustion using an acceleration sensor optimized for the normal combustion mode, the effect of structural damping will be significant, and the vibrational acceleration detected by the acceleration sensor will be greatly affected. value becomes very small.

Further, when the combustion mode is changed from the normal combustion mode to the combustion mode in which the combustion period is shortened, the center frequency of combustion shifts to the high frequency side. At this time, if an acceleration sensor optimized for normal combustion mode is used to detect the vibrational acceleration caused by the combustion of the internal combustion engine, the effect of structural damping becomes extremely small and the vibrational acceleration is measured excessively. It may get lost.

In this way, the vibration acceleration detected by the acceleration sensor attached to the internal combustion engine is affected by the structural damping determined by the mounting state of the acceleration sensor. The signal obtained by the acceleration sensor becomes too small or too large. For this reason, there is a problem that sufficient accuracy cannot be obtained as a detection value of the vibration acceleration obtained by the acceleration sensor, and an error occurs in determining the ignition timing.

This disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a control device for an internal combustion engine that can make it difficult for errors to occur in specifying ignition timing even if the combustion mode changes. An object of the present invention is to provide an engine system and a control method for an internal combustion engine system.

A control device for an internal combustion engine according to this disclosure is attached to a main body of an internal combustion engine having a plurality of cylinders, and includes a plurality of acceleration sensors for detecting vibrational acceleration of the internal combustion engine caused by combustion of fuel in the cylinders, and an acceleration sensor. and a control unit that specifies fuel ignition timing using the detected vibrational acceleration. The plurality of acceleration sensors are arranged in the internal combustion engine such that damping characteristics of vibration acceleration caused by combustion of fuel in the predetermined cylinder detected by each acceleration sensor are different for predetermined cylinders among the plurality of cylinders. The attachment to the body of the is adjusted. The control unit specifies a specific frequency band including a central frequency of combustion according to the combustion mode for a predetermined cylinder among the plurality of cylinders, and detects vibration acceleration in the specified specific frequency band from among the plurality of acceleration sensors. At least one acceleration sensor with low attenuation is specified, and the ignition timing of the predetermined cylinder is specified using the vibration acceleration detected by the at least one specified acceleration sensor.

Preferably, the plurality of acceleration sensors have different damping characteristics of vibration acceleration by having different shapes of attachment portions to the main body of the internal combustion engine.

An internal combustion engine system according to another aspect of this disclosure includes an internal combustion engine having a plurality of cylinders and a plurality of acceleration sensors attached to a body of the internal combustion engine for detecting vibrational acceleration of the internal combustion engine resulting from combustion of fuel in the cylinders. A sensor and a control unit that specifies fuel ignition timing using vibration acceleration detected by the acceleration sensor. The plurality of acceleration sensors are arranged in the internal combustion engine such that damping characteristics of vibration acceleration caused by combustion of fuel in the predetermined cylinder detected by each acceleration sensor are different for predetermined cylinders among the plurality of cylinders. The attachment to the body of the is adjusted. The control unit specifies a specific frequency band including the center frequency of combustion according to the combustion mode for a predetermined cylinder among the plurality of cylinders, and attenuates the vibration acceleration in the specified specific frequency band from among the plurality of acceleration sensors. At least one acceleration sensor with a small acceleration sensor is specified, and the ignition timing of the predetermined cylinder is specified using the vibration acceleration detected by the specified at least one acceleration sensor.

Preferably, the plurality of acceleration sensors have different damping characteristics of vibration acceleration by having different shapes of attachment portions to the main body of the internal combustion engine.

In a method for controlling an internal combustion engine system according to yet another aspect of the present disclosure, the internal combustion engine system includes an internal combustion engine having a plurality of cylinders, and an internal combustion engine attached to a body of the internal combustion engine and caused by combustion of fuel in the cylinders. a plurality of acceleration sensors for detecting the vibration acceleration of the acceleration sensor; and a control section for specifying fuel ignition timing using the vibration acceleration detected by the acceleration sensor. The plurality of acceleration sensors are arranged in the internal combustion engine such that damping characteristics of vibration acceleration caused by combustion of fuel in the predetermined cylinder detected by each acceleration sensor are different for predetermined cylinders among the plurality of cylinders. The attachment to the body of the is adjusted. In the control method, the control unit specifies a specific frequency band including the center frequency of combustion according to the combustion mode for a predetermined cylinder among the plurality of cylinders, and selects the specified specific frequency band from among the plurality of acceleration sensors. identifying at least one acceleration sensor whose acceleration attenuation is small; and identifying the ignition timing of a predetermined cylinder using the acceleration detected by the identified at least one acceleration sensor.

According to this disclosure, it is possible to provide an internal combustion engine system design method, an internal combustion engine system, and an internal combustion engine system control method that make it difficult for errors to occur in specifying ignition timing even if the combustion mode changes. can be done.

It is a figure which shows the schematic structure of the periphery of the engine in this embodiment. 4 is a flow chart showing the flow of mounting design for the acceleration sensor in this embodiment. It is a figure for demonstrating the attachment method of an acceleration sensor. FIG. 4 is a diagram for explaining differences in damping characteristics for each frequency of engine vibration acceleration caused by fuel combustion detected by an acceleration sensor attached to a cylinder block; FIG. 4 is a diagram showing the relationship between a combustion excitation force detected by an in-cylinder pressure sensor and an acceleration value detected by an acceleration sensor; FIG. 4 is a diagram for explaining differences in engine combustion excitation force due to combustion of fuel for each frequency; FIG. 4 is a diagram for explaining the relationship between the crank angle and heat release rate for each combustion mode; 4 is a flow chart showing the flow of ignition timing correction processing in this embodiment. FIG. 7 is a diagram illustrating a method of identifying an acceleration sensor that is less affected by structural damping of vibration acceleration in the identified frequency band; It is a figure which shows the time change of the vibration acceleration of a specific frequency band.

Embodiments of the present disclosure will be described below with reference to the drawings. In the following description, identical parts are provided with identical reference numerals. Their names and functions are also the same. A detailed description thereof will therefore not be repeated.

FIG. 1 is a diagram showing a schematic configuration of an engine system in this embodiment. Referring to FIG. 1, this engine system includes an engine 10, an intake path 30 that supplies air to the engine 10, an exhaust path 40 that discharges exhaust from the engine 10, and an electronic control unit that controls the engine 10 ( 100, and acceleration sensors 110A, 110B, and 110C (hereinafter collectively referred to as "acceleration sensors 110") for detecting vibration acceleration of engine 10. The engine system is mounted on a vehicle, for example.

In this embodiment, the engine 10 is described as a diesel engine, but the type of engine is not limited to this, and the engine 10 may be a gasoline engine. Each cylinder 11 of the engine 10 is provided with a fuel injection valve 20 . The combustion chamber 12 is formed by a piston that reciprocates up and down inside the cylinder 11 , a cylinder head that seals the upper portion of the cylinder 11 , and the cylinder 11 . Air is supplied to the combustion chamber 12 from an intake path 30 . Each fuel injection valve 20 is supplied with fuel from a fuel tank by a fuel pump. Each fuel injection valve 20 is operated (opened) by a control signal from the ECU 100 to inject fuel into the air in the combustion chamber 12 . Exhaust is discharged from the combustion chamber 12 to an exhaust path 40 .

The engine 10 is a four-stroke engine, and operates in one cycle including an intake stroke, a compression stroke, an expansion (combustion) stroke, and an exhaust stroke. In the intake stroke, air is drawn into the combustion chamber 12 from the intake path 30 by inertia of the piston in the cylinder 11 moving down to the bottom dead center. In the compression stroke, the air in the combustion chamber 12 is compressed and heated as the piston moves up to the top dead center due to inertia. In the expansion stroke, fuel is injected from the fuel injection valve 20 into the high-temperature, high-pressure air in the combustion chamber 12, and the fuel self-ignites, so that the expanded combustion gas pushes the piston down to the bottom dead center. In the exhaust stroke, the combustion gas in the combustion chamber 12 is discharged from the combustion chamber 12 to the exhaust path 40 as exhaust as the piston moves up to the top dead center due to inertia. The engine 10 converts the vertical motion of the piston into rotary motion and outputs power to the outside.

The acceleration sensors 110A, 110B, and 110C detect acceleration of vibration of the engine 10 due to combustion of fuel in the combustion chamber 12, etc., and output detection results to the ECU 100. FIG. Acceleration sensors 110A, 110B, 110C are attached to different positions of the cylinder block of engine 10. FIG. Note that the number of acceleration sensors 110 is three in this disclosure, but is not limited to this, and may be any number.

The ECU 100 includes a CPU (Central Processing Unit) 101, a memory 102, and an input/output port for inputting/outputting various signals. The memory 102 includes ROM (Read Only Memory) and RAM (Random Access Memory). In ECU 100, CPU 101 controls each device using RAM as a work memory based on signals from each sensor (for example, acceleration sensor 110) and devices, programs stored in ROM of memory 102, and the like. Various controls are not limited to processing by software, and can be processed by dedicated hardware (electronic circuits).

Conventionally, the acceleration detected by the acceleration sensor 110 is integrated over a certain interval, and when the integrated value exceeds the ignition timing determination level, the fuel ignition timing is determined. In such an engine 10, the acceleration detected by the acceleration sensor 110 is affected by structural damping. In addition to the fact that the obtained signal is small, the acceleration detection value obtained by the acceleration sensor 110 cannot be obtained with sufficient accuracy. there were.

Therefore, in this embodiment, the design method of the engine system is such that the plurality of acceleration sensors 110A are arranged so that the damping characteristics of the vibrational acceleration caused by the combustion of fuel in a predetermined cylinder among the plurality of cylinders 11 are different. , 110B, 110C to the main body of the engine 10 is adjusted. The ECU 100 identifies a specific frequency band including the central frequency of combustion for a predetermined cylinder according to the combustion mode, and selects from among the plurality of acceleration sensors 110A, 100B, and 110C the specific frequency band in which vibration acceleration attenuation is small. At least one acceleration sensor is specified, and the ignition timing of the predetermined cylinder is specified using the vibration acceleration detected by the specified at least one acceleration sensor. As a result, it is possible to prevent an error from occurring in determining the ignition timing even if the combustion mode changes.

FIG. 2 is a flow chart showing the flow of mounting design of the acceleration sensor in this embodiment. Referring to FIG. 2, first, the mounting positions of the plurality of acceleration sensors 110A, 110B, 110C to the cylinder block of engine 10 are determined (step S101). The mounting positions of the plurality of acceleration sensors 110A, 110B, 110C are determined to be different positions.

Next, design is made so that a plurality of acceleration sensors 110 are attached to the determined attachment positions by a standard method (step S102).

FIG. 3 is a diagram for explaining how to attach the acceleration sensor. FIG. 3A is a diagram for explaining how the acceleration sensor 110 is attached by the standard method. Referring to FIG. 3A, in this embodiment, the standard method for mounting acceleration sensor 110 is to fasten pedestal 112 and acceleration sensor 110 to the cylinder block of engine 10 with bolts 111A of length L. It is a way to The standard method may be any other method.

Returning to FIG. 2, next, in an actual or simulated engine system, the engine 10 is brought into operation under various predetermined operating conditions, and a predetermined cylinder 11 (for example, the cylinder furthest from the timing chain or timing belt of the engine 10) is operated. 11) Record the combustion excitation force obtained by the in-cylinder pressure sensor that detects the pressure of the combustion chamber 12 inside, and the vibration acceleration obtained by the plurality of acceleration sensors 110A, 110B, and 110C (step S103). The in-cylinder pressure sensor is provided in the cylinder 11 to measure the combustion state during the development process of the engine 10 . The predetermined cylinder 11 may be another cylinder 11 .

Then, using the recorded combustion exciting force and vibrational acceleration, it is determined whether or not the frequency bands in which the vibrational acceleration is less damped are different for each of the plurality of acceleration sensors 110A, 110B, and 110C (step S104).

FIG. 4 is a diagram for explaining the difference in damping characteristics for each frequency of the vibrational acceleration of the engine 10 caused by fuel combustion detected by an acceleration sensor attached to the cylinder block. When fuel burns in the combustion chamber 12 in the cylinder 11 of the engine 10, vibrations are generated due to the combustion. This vibration is attenuated in the process of propagating through a structure such as the cylinder block of the engine 10, and is detected as vibration acceleration by the acceleration sensor. However, the vibration damping characteristics of this structure (influence of structural damping for each frequency band) differ depending on the mounting position and mounting state of the sensor. Therefore, in order to accurately detect the vibration acceleration caused by combustion with the acceleration sensor, it is necessary to adjust the mounting state of the acceleration sensor so that the effect of structural damping is small in the frequency band you want to detect, or It is necessary to select an acceleration sensor that is less affected by structural damping. For example, in the acceleration sensor having the structural damping characteristics shown in FIG. 4, the structural damping is large in the low-frequency region and small in the high-frequency region. Vibrational acceleration due to combustion can be detected. Conversely, in the low-frequency region, structural damping has a large effect, so the detected value becomes very small, and there is a fear that the change in acceleration cannot be detected accurately.

FIG. 5 is a diagram showing the relationship between the combustion excitation force obtained by the in-cylinder pressure sensor and the acceleration sensor value obtained by the acceleration sensor. Referring to FIG. 5, the relationship between the combustion excitation force and the acceleration sensor value is approximately linear. When only one acceleration sensor is attached to the cylinder block as in the conventional method, when the combustion mode is changed from combustion mode A to combustion mode B, the detection value of the acceleration sensor is affected by structural damping. The combustion excitation force also causes a difference in the detected value of the acceleration sensor. That is, in the conventional method in which only one acceleration sensor is attached to the cylinder block, it is difficult to specify the ignition timing from the detection value of the acceleration sensor in an engine in which the combustion mode is changed.

FIG. 6 is a diagram for explaining the difference for each frequency in the combustion excitation force of the engine 10 caused by fuel combustion. Referring to FIG. 6 , in engine 10 , combustion excitation force is generated due to fuel combustion in combustion chamber 12 in cylinder 11 . The combustion excitation force can be detected by an in-cylinder pressure sensor. Fourier transformation of the time change of the combustion excitation force detected by the in-cylinder pressure sensor yields the magnitude of the combustion excitation force for each frequency component, as shown in FIG. The magnitude of the combustion excitation force for each frequency component differs depending on the combustion mode. Compared to combustion mode A, in combustion mode B, the combustion excitation force is small in the relatively low frequency band C, and the combustion excitation force is large in the relatively high frequency band D.

FIG. 7 is a diagram for explaining the relationship between the crank angle and the heat release rate for each combustion mode. Referring to FIG. 7, in the case of a combustion mode in which the combustion period in one cycle is long as shown in FIG. Combustion excitation force increases. As shown in FIG. 7B, in the case of a combustion mode in which the combustion period in one cycle is short, the change in the heat release rate is relatively steep, so the combustion excitation force in the high frequency band increases. . Due to these factors, the magnitude of the combustion excitation force for each frequency component varies depending on the combustion mode.

Returning to FIG. 2, when it is determined that the frequency bands in which the vibration acceleration is less attenuated are different among the plurality of acceleration sensors 110A, 110B, and 110C (YES in step S104), the mounting design of the acceleration sensors ends.

On the other hand, if it is determined that the frequency bands with low vibration acceleration attenuation are not different among the plurality of acceleration sensors 110A, 110B, and 110C (NO in step S104), the acceleration sensor 110 whose mounting method is to be adjusted is selected (step S106). For example, if there are a plurality of acceleration sensors 110 having similar frequency bands with low damping of vibration acceleration, one of them is selected as the acceleration sensor to be adjusted.

Next, the mounting method of the selected acceleration sensor 110 is adjusted so as to improve the attenuation of the target frequency band (step S107). The target frequency band is, for example, a frequency band in which vibration acceleration is less attenuated from any of the acceleration sensors 110 other than the selected acceleration sensor 110 .

Referring to FIG. 3 again, as shown in FIG. 3B, the pedestal 112 is filled with a welded build-up 113 to change the shape of the pedestal, and the length of the bolt 111B for attaching the acceleration sensor 110 is changed to If the length of the bolt 111A is longer than that of the bolt 111A shown in FIG. 3A, structural damping of vibration acceleration in all frequency bands is increased. Conversely, if the mounting bolts are shortened, the structural damping of vibration acceleration in all frequency bands increases. Further, if the thickness of the bolt is made thin, the structural damping of the vibration acceleration in all frequency bands becomes small, and if the thickness of the bolt is made thick, the structural damping of the vibration acceleration in all frequency bands becomes large. Structural damping of vibration acceleration in all frequency bands also differs depending on the shape of the pedestal. By combining these changes, adjustments are made in the direction of improving the attenuation of the target frequency band.

Returning to FIG. 2, after step S107, steps S103 to S107 are repeated until all the acceleration sensors have different frequency bands in which vibration acceleration is less attenuated.

FIG. 8 is a flowchart showing the flow of ignition timing correction processing in this embodiment. This ignition timing correcting process is called and executed by the ECU 100 from the main process every predetermined control cycle. Referring to FIG. 8, CPU 101 of ECU 100 acquires acceleration values from a plurality of acceleration sensors 110A, 110B, and 110C (step S111), and stores the acquired acceleration values in the RAM of memory 102 in chronological order (step S102). ).

The CPU 101 determines whether or not it is time to specify the ignition timing (step S113). In this embodiment, the timing for specifying the ignition timing is each time the vehicle travels a predetermined distance (eg, 5000 km, 10000 km, etc.), but is not limited to this, and may be other timing. For example, in order to improve the performance of the engine or extend the service life of the engine, if it is better to check the ignition timing frequently, such as in situations where the composition of the fuel fluctuates greatly, the timing to specify the ignition timing is , or every predetermined control period when the ignition timing control process is called from the main process.

When determining that it is not the timing to specify the ignition timing (NO in step S113), the CPU 101 returns the processing to be executed to the main processing that called the ignition timing specifying processing. On the other hand, if it is determined that it is time to specify the ignition timing (YES in step S113), the CPU 101 acquires the current combustion mode, and from the combustion period in that combustion mode, the combustion of fuel in the predetermined cylinder 11 is performed. A specific frequency band is specified that includes the center frequency of combustion with moderately large vibration acceleration and does not contain excessive vibration acceleration frequencies other than vibration acceleration caused by . The central frequency of combustion is specified in advance by experiment or simulation for each combustion mode and combustion period. In addition, the frequency of excessive vibrational acceleration other than the vibrational acceleration caused by combustion of fuel in a predetermined cylinder 11 is also specified in advance by experiments or simulations.

As shown in FIG. 7, the change in the heat release rate differs depending on the combustion mode, so the characteristics of the frequency component of the combustion excitation force differ. As shown in FIG. 5, there is a linear functional relationship between the combustion excitation force and the vibration acceleration. Therefore, the characteristics of the frequency component of the vibration acceleration differ depending on the combustion mode.

For example, in the case of combustion mode A with a relatively long combustion period as shown in FIG. 7A, as shown in FIG. Vibration acceleration in the low frequency band C increases. Therefore, in the case of combustion mode A with a relatively long combustion period, the frequency of excessive vibrational acceleration other than the vibrational acceleration caused by the combustion of fuel in the predetermined cylinder 11 is minimized, and the vibrational acceleration is moderately controlled. A frequency band C is identified as a specific frequency band containing a large central frequency of combustion.

Further, in the case of combustion mode B with a relatively short combustion period as shown in FIG. 7B, as shown in FIG. Vibration acceleration in the high frequency band D increases. Therefore, in the case of the combustion mode B in which the combustion period is relatively short, the frequency of excessive vibration acceleration other than the vibration acceleration caused by the combustion of the fuel in the predetermined cylinder 11 is minimized, and the vibration acceleration is moderately controlled. A frequency band D is identified as a specific frequency band containing a large central frequency of combustion.

Returning to FIG. 8, next, the CPU 101 identifies the acceleration sensor 110 with less attenuation in the specific frequency band identified in step S114 (step S115). In this embodiment, the acceleration sensor 110 with the least attenuation in the specific frequency band is specified as the acceleration sensor 110 with the least attenuation in the specific frequency band.

FIG. 9 is a diagram illustrating a method of identifying an acceleration sensor that is less affected by structural damping of vibration acceleration in the frequency band identified in step S114. By Fourier transforming the time change of the vibration acceleration detected by the acceleration sensor 110, the magnitude of the vibration acceleration for each frequency component can be obtained. As shown in FIG. Therefore, it is necessary to select the optimum acceleration sensor according to the combustion mode. Therefore, as shown in FIG. 9, the frequency band is divided into a plurality of bands in advance, and numbers from N=1 to N are assigned to the respective divided frequency bands. Then, as described with reference to FIG. 2, at the time of design, the number of the frequency band with less structural damping is specified for each acceleration sensor. For example, compared to combustion mode A, in combustion mode B, the combustion excitation force is smaller in relatively low frequency band C, and the combustion excitation force is larger in relatively high frequency band D. When acquiring the vibration acceleration of the combustion mode B with an acceleration sensor, as shown in FIG. Select an accelerometer with low attenuation.

Returning to FIG. 8, the CPU 101 reads from the memory 102 the temporal change in the acceleration value of the specified acceleration sensor 110, and Fourier-transforms the temporal change in the read acceleration value to calculate the frequency distribution of the acceleration value (step S116).

Next, the CPU 101 performs an inverse Fourier transform on the vibration acceleration in a specific frequency band in the frequency distribution of the calculated acceleration values, thereby calculating the time change of the vibration acceleration (step S117). As a result, it is possible to obtain the time change of the vibration acceleration excluding the influence of the vibration acceleration in the frequency band weakened by the structural damping.

Next, the CPU 101 identifies the ignition timing from the calculated temporal change in the vibration acceleration (step S118).

FIG. 10 is a diagram showing temporal changes in vibration acceleration in a specific frequency band. Referring to FIG. 10, in the graph of the time change of the vibration acceleration, the point of time of the zero cross point immediately before the point where the amplitude exceeds the determination threshold can be specified as the ignition timing.

Returning to FIG. 8, the CPU 101 uses the identified ignition timing to correct the injection timing used to control fuel injection (step S119). For example, if the ignition timing is earlier than the assumed timing by a predetermined time, the injection timing is advanced by a predetermined time. Conversely, if the ignition timing is later than the assumed timing by a predetermined time, the injection timing is delayed by a predetermined time. After that, the CPU 101 returns the process to be executed to the main process that called the ignition timing specifying process.

[Modification]
(1) In the above-described embodiment, as shown in FIG. 3, the acceleration sensor 110 is fastened to the cylinder block with one bolt. However, the present invention is not limited to this, and as long as the acceleration sensor 110 is attached to any portion such as the cylinder block of the engine 10, it may be attached by other methods. Acceleration sensor 110 may be fixed with a plurality of screws.

(2) In the above-described embodiment, the acceleration sensor 110 is mounted by changing the size and shape of the weld overlay 113, the pedestal 112, and the bolts 111A and 111B. The structural damping of the vibration acceleration of the engine 10 is adjusted. However, the method of adjusting structural damping is not limited to this and may be other methods, for example, by changing the shape or weight of engine parts such as the cylinder block.

(3) In the above-described embodiment, as shown in FIG. 2, the mounting method of the acceleration sensor is designed so that the frequency bands with less vibration acceleration attenuation (amount) are different as a feature of vibration acceleration attenuation. I made it However, the vibration acceleration damping feature is not limited to this, and may be, for example, a frequency band with a low vibration acceleration damping rate.

(4) In the above-described embodiment, as shown in step S117 in FIG. 8, the vibration acceleration in a specific frequency band with large vibration acceleration is subjected to inverse Fourier transform to calculate the time change of the vibration acceleration. . However, the present invention is not limited to this, and the time change of the vibration acceleration may be calculated by inverse Fourier transforming the vibration acceleration of all frequency bands.

(5) In the above-described embodiment, as shown in FIG. 8, the specified ignition timing is used to correct the injection timing. However, the invention is not limited to this, and the specified ignition timing may be used for other purposes, such as failure determination. In this case, for example, if the error between the specified ignition timing and the assumed ignition timing is greater than or equal to a predetermined value, it may be determined that there is a failure.

(6) The above-described embodiment can be regarded as disclosure of a control device such as the ECU 100 of an internal combustion engine such as the engine 10 or disclosure of a control method by the control device. Moreover, it can be regarded as disclosure of an internal combustion engine system including such an internal combustion engine and a control device. It can also be taken as disclosure of a design method for an internal combustion engine system.

[effect]
(1-1) As shown in FIG. 1, in the engine system design method, the engine system includes an engine 10 having a plurality of cylinders 11, and a body of the engine 10, which is attached to the body of the engine 10 and burns fuel in the cylinders 11. a plurality of acceleration sensors 110A, 110B, and 110C for detecting vibration acceleration of the engine 10 caused by the acceleration sensor 110; As shown in FIG. 8, the ECU 100 identifies a specific frequency band including the central frequency of combustion according to the combustion mode for a predetermined cylinder 11 out of the plurality of cylinders, and sets the acceleration sensors 110A, 100B, 110C. Among them, at least one acceleration sensor 110 whose vibration acceleration is less damped in the specified specific frequency band is specified, and the vibration acceleration detected by the specified at least one acceleration sensor 110 is used to ignite a predetermined cylinder 11 Identify when. As shown in FIG. 2, the design method is such that the acceleration sensors 110A, 110B, and 110C of the body of the engine 10 are arranged so that the damping characteristics of the vibrational acceleration caused by the combustion of fuel in a given cylinder 11 are different. including adjusting the attachment to the

As a result, it is possible to provide an engine system designing method that makes it difficult for errors to occur in specifying the ignition timing even if the combustion mode changes.

(1-2) As shown in FIG. 3, the step of adjusting the mounting of the plurality of acceleration sensors 110A, 110B, and 110C includes adjusting the shape of the mounting portion of the plurality of acceleration sensors 110A, 110B, and 110C to the main body of the engine 10. and adjusting the mounting of the plurality of acceleration sensors 110A, 110B, 110C so that the damping characteristics of the vibration acceleration are different. Accordingly, it is possible to appropriately adjust the mounting method of the acceleration sensors 110A, 110B, and 110C.

(2-1) As shown in FIG. 1, the engine system includes an engine 10 having a plurality of cylinders 11 and a body of the engine 10 that is attached to the body of the engine 10. It includes a plurality of acceleration sensors 110A, 110B, 110C that detect acceleration, and an ECU 100 that specifies fuel ignition timing using the vibration acceleration detected by the acceleration sensors 110A, 110B, 110C. As shown in FIG. 2, the plurality of acceleration sensors 110A, 110B, and 110C correspond to a predetermined cylinder 11 among the plurality of cylinders 11, and the predetermined cylinder 11 detected by each of the acceleration sensors 110A, 110B, and 110C. The mounting to the body of the engine 10 is tailored to provide different vibrational acceleration damping characteristics due to combustion of fuel therein. As shown in FIG. 8, the ECU 100 identifies a specific frequency band including the central frequency of combustion in accordance with the combustion mode for a predetermined cylinder 11 out of the plurality of cylinders, and the acceleration sensors 110A, 110B, 110C. Among them, at least one acceleration sensor 110 with low damping of vibration acceleration in the specified specific frequency band is specified, and the vibration acceleration detected by the specified at least one acceleration sensor is used to determine the ignition timing of the cylinder 11 identify.

As a result, it is possible to provide an engine system that makes it difficult for errors to occur in identifying the ignition timing even if the combustion mode changes.

(2-2) As shown in FIG. 2, by varying the shapes of the mounting portions of the plurality of acceleration sensors 110A, 110B, and 110C to the main body of the engine 10, the damping characteristics of vibration acceleration are varied. . Accordingly, the mounting of the acceleration sensors 110A, 110B, 110C to the engine 10 can be appropriately adjusted.

It is also planned to implement each embodiment disclosed this time in appropriate combination. And the embodiment disclosed this time should be considered as an illustration and not restrictive in all respects. The scope of the present disclosure is indicated by the scope of claims rather than the description of the above-described embodiments, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

10 engine, 11 cylinder, 12 combustion chamber, 20 fuel injection valve, 30 intake path, 40 exhaust path, 100 ECU, 110, 110A, 110B, 110C acceleration sensor, 101 CPU, 102 memory, 111A, 111B bolt, 112 base, 113 Meat plate.

Claims (3)

a plurality of acceleration sensors attached to a body of an internal combustion engine having a plurality of cylinders for detecting vibrational acceleration of the internal combustion engine caused by combustion of fuel in the cylinders;
A control unit that specifies fuel ignition timing using the vibration acceleration detected by the acceleration sensor,
The plurality of acceleration sensors are arranged so that attenuation characteristics of vibration acceleration caused by combustion of fuel in the predetermined cylinder detected by each acceleration sensor are different for a predetermined cylinder among the plurality of cylinders. , the attachment to the body of the internal combustion engine is adjusted,
The control unit
For the predetermined cylinder among the plurality of cylinders, a specific frequency band including a central frequency of combustion is specified according to the combustion mode, and vibration acceleration is damped in the specified specific frequency band from among the plurality of acceleration sensors. identifying at least one of the acceleration sensors with less
identifying the ignition timing of the predetermined cylinder using the vibration acceleration detected by the identified at least one acceleration sensor;
The control device for an internal combustion engine , wherein the plurality of acceleration sensors have different vibration acceleration damping characteristics by differentiating shapes of attachment portions to the main body of the internal combustion engine. an internal combustion engine having a plurality of cylinders;
a plurality of acceleration sensors attached to the body of the internal combustion engine for detecting vibrational acceleration of the internal combustion engine caused by combustion of fuel in the cylinder;
A control unit that specifies fuel ignition timing using the vibration acceleration detected by the acceleration sensor,
The plurality of acceleration sensors are arranged so that attenuation characteristics of vibration acceleration caused by combustion of fuel in the predetermined cylinder detected by each acceleration sensor are different for a predetermined cylinder among the plurality of cylinders. , the attachment to the body of the internal combustion engine is adjusted,
The control unit
For the predetermined cylinder among the plurality of cylinders, a specific frequency band including a central frequency of combustion is specified according to the combustion mode, and vibration acceleration is damped in the specified specific frequency band from among the plurality of acceleration sensors. identifying at least one of the acceleration sensors with less
identifying the ignition timing of the predetermined cylinder using the vibration acceleration detected by the identified at least one acceleration sensor;
The internal combustion engine system according to claim 1, wherein the plurality of acceleration sensors have different vibration acceleration damping characteristics by differentiating shapes of attachment portions to the main body of the internal combustion engine. A control method for an internal combustion engine system, comprising:
The internal combustion engine system includes:
an internal combustion engine having a plurality of cylinders;
a plurality of acceleration sensors attached to the body of the internal combustion engine for detecting vibrational acceleration of the internal combustion engine caused by combustion of fuel in the cylinder;
A control unit that specifies fuel ignition timing using the vibration acceleration detected by the acceleration sensor,
The plurality of acceleration sensors are arranged so that attenuation characteristics of vibration acceleration caused by combustion of fuel in the predetermined cylinder detected by each acceleration sensor are different for a predetermined cylinder among the plurality of cylinders. , the attachment to the body of the internal combustion engine is adjusted,
In the control method, the control unit
A specific frequency band including a central frequency of combustion is specified according to a combustion mode for the predetermined cylinder among the plurality of cylinders, and acceleration attenuation is detected in the specified specific frequency band from among the plurality of acceleration sensors. identifying fewer at least one of said acceleration sensors;
and identifying the ignition timing of the predetermined cylinder using the acceleration detected by the identified at least one acceleration sensor ,
A control method for an internal combustion engine system , wherein the plurality of acceleration sensors have different vibration acceleration damping characteristics by differentiating shapes of attachment portions to the main body of the internal combustion engine.

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