JP2015113805A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of determining a level of combustion noise on the basis of an output signal of a crank angle sensor.SOLUTION: A frequency spectrum with respect to a part corresponding to a combustion stroke of a cylinder 12 in an output signal of a crank angle sensor 40 is determined. The more a component of a prescribed frequency in the frequency spectrum is, the higher the level of a combustion noise is determined. The prescribed frequency is a frequency corresponding to the order half of the number of cylinders to an engine speed in the combustion stroke. As an engine 10 is a 4-stroke 4-cylinder engine, and generates the combustion noise in secondary rotation order, the level of the combustion noise can be evaluated by evaluating a size of the frequency component of the secondary rotational order. A size of a frequency band component of a prescribed width having a spread near the frequency component equivalent to the secondary rotational order, is preferably evaluated, as actually a fuel injection time may be retarded or advanced.

Description

  The present invention relates to an internal combustion engine.

  Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-233839, an internal combustion engine that performs control for suppressing combustion noise using an in-cylinder pressure sensor is known. The control device according to this publication determines whether or not the combustion noise has become excessive based on whether or not the in-cylinder pressure change rate (that is, dP / dt or dP / dθ) is greater than a predetermined change rate dPth.

JP 2006-233839 A JP 2011-117420 A JP 2006-183533 A

  The in-cylinder pressure sensor includes a sensor unit that is directly exposed in the cylinder. If unburned components in the cylinder accumulate on the sensor portion, the sensitivity of the in-cylinder pressure sensor is reduced. In addition, there are a large number of internal combustion engines that are not equipped with an in-cylinder pressure sensor. In view of these points, the inventors of the present invention have conducted extensive research and have focused on the physical phenomenon that the magnitude of the specific frequency component included in the crank angular velocity waveform correlates with the magnitude of combustion noise. A new technique has been found that uses this physical phenomenon to control or diagnose an internal combustion engine related to combustion noise.

  The present invention has been made to solve the above-described problems, and can control or diagnose an internal combustion engine related to combustion noise by utilizing the point at which combustion noise appears in the rotation of the crankshaft. An object is to provide an internal combustion engine.

In order to achieve the above object, a first invention is an internal combustion engine,
A crank angle sensor that is a sensor that emits an output signal corresponding to the rotation of a crankshaft connected to a piston provided in a cylinder of an internal combustion engine;
A function defining a relationship between the input and the control amount of the internal combustion engine or a relationship between the input and the diagnosis result of the internal combustion engine, and at least a portion corresponding to a combustion stroke of the cylinder of the output signal of the crank angle sensor The frequency analysis is performed on the internal combustion engine according to the control amount or the diagnosis result output by the function, and the value of the frequency component that increases as the combustion noise increases among the frequency components included in the portion is input to the function. A control device for controlling or diagnosing
It is characterized by providing.
The frequency that increases as the combustion noise increases may be a predetermined frequency.

According to a second invention, in the first invention,
The function is characterized in that as the input value is larger, the control amount is output so as to further suppress combustion noise.

According to a third invention, in the first or second invention,
The function alternatively outputs a control start signal and a stop signal that suppress combustion noise in accordance with the magnitude of the input value.

A fourth invention is any one of the first to third inventions,
The function is characterized in that a diagnosis result indicating whether a combustion noise abnormality has occurred or not is output according to the magnitude of the input value.

In a fifth invention, in any one of the first to fourth inventions,
A cylinder pressure sensor provided on the cylinder;
The control device calculates the value of the magnitude of combustion noise based on the output signal of the in-cylinder pressure sensor,
The function uses the magnitude value obtained from the output signal of the crank angle sensor as a first input, the combustion noise magnitude value obtained from the in-cylinder pressure sensor as a second input, and the first input. A diagnostic result indicating that at least one of the crank angle sensor and the in-cylinder pressure sensor is abnormal is output according to the magnitude of the difference from the second input.

A sixth invention is any one of the first to fifth inventions,
An in-cylinder pressure sensor provided in the cylinder;
An informing means for informing the abnormality of the internal combustion engine;
With
The control device calculates the value of the magnitude of combustion noise based on the output signal of the in-cylinder pressure sensor,
The function uses the magnitude value obtained from the output signal of the crank angle sensor as a first input, the combustion noise magnitude value obtained from the in-cylinder pressure sensor as a second input, and the first input. A different signal is output to the notification means according to the magnitude of the difference from the second input.

In a seventh invention, in any one of the first to sixth inventions,
A plurality of the cylinders are provided, and pistons of the cylinders are connected to a common crankshaft,
The control device inputs, into the function, a magnitude value of a frequency component corresponding to an order that is half the number of cylinders with respect to the engine speed during the combustion stroke, among the frequency components included in the portion. And

According to an eighth invention, in any one of the first to seventh inventions,
The control device periodically samples a portion away from a crank angular velocity peak position with respect to an output signal of the crank angle sensor, and performs frequency analysis on the sampled portion.

In a ninth aspect based on the eighth aspect,
The controller is
Noise transmission time until combustion noise in the cylinder is transmitted to the crank angle sensor based on the fuel injection amount to the cylinder, the fuel injection timing to the cylinder, and the position of the piston in the cylinder The longer the is, the larger the amount of the crank angular velocity peak position away from the sampling portion is set.

  According to the first aspect of the present invention, the magnitude of the frequency component corresponding to the combustion noise in the sensor output signal is obtained, and the magnitude of this frequency component is input to a function relating the combustion noise to the control amount or diagnosis result of the internal combustion engine. Include as a variable. As a result, it is possible to perform control or diagnosis related to combustion noise using a sensor capable of detecting rotation of the crankshaft.

  According to the second aspect of the invention, it is possible to perform control for suppressing combustion noise and adjust the amount of suppression based on the output signal of the crank angle sensor.

  According to the third invention, it is possible to execute or stop the control for suppressing the combustion noise by using the magnitude of the frequency component corresponding to the combustion noise as an index.

  According to the fourth invention, the magnitude of the combustion noise can be determined using the magnitude of the frequency component corresponding to the combustion noise included in the output signal of the crank angle sensor as an index.

  According to the fifth invention, by investigating the difference between the combustion noise obtained from the output signal of the crank angle sensor and the combustion noise obtained from the output signal of the in-cylinder pressure sensor, at least one of these sensors is investigated. On the other hand, it can be diagnosed whether the original performance is exhibited.

  According to the sixth aspect of the present invention, by investigating the difference between the combustion noise obtained from the output signal of the crank angle sensor and the combustion noise obtained from the output signal of the in-cylinder pressure sensor, at least one of these sensors is detected. On the other hand, it is possible to diagnose whether the original performance is exhibited and to recognize the diagnosis result from the outside of the control device.

  According to the seventh aspect, since the frequency component to be evaluated is determined in accordance with the timing at which the combustion timing appears in the output signal of the crank angle sensor, the combustion noise can be accurately evaluated.

  According to the eighth aspect of the invention, since the output signal at a specific timing suitable for combustion noise evaluation is sampled, the component due to the combustion noise in the output signal can be accurately extracted.

  According to the ninth aspect, the longer the noise transmission time until the combustion noise is transmitted to the crank angle sensor, the more the sampling timing is delayed, so that the portion where the combustion noise appears in the output signal can be sampled with high accuracy.

1 is a diagram showing an internal combustion engine according to a first embodiment of the present invention. 1 is a diagram showing an internal combustion engine according to a first embodiment of the present invention. It is a figure for demonstrating the control content of the control apparatus in the internal combustion engine concerning Embodiment 1 of this invention. It is a figure for demonstrating the control content of the control apparatus in the internal combustion engine concerning Embodiment 1 of this invention. It is a figure for demonstrating the control content of the internal combustion engine concerning Embodiment 1 of this invention. It is a flowchart of the routine which a control apparatus performs in the internal combustion engine concerning Embodiment 1 of this invention. It is a flowchart of the routine which a control apparatus performs in the internal combustion engine concerning Embodiment 1 of this invention. It is a flowchart of the routine which a control apparatus performs in the internal combustion engine concerning Embodiment 2 of this invention. It is a flowchart of the routine which a control apparatus performs in the internal combustion engine concerning Embodiment 2 of this invention.

Embodiment 1 FIG.
[Configuration of Device of Embodiment 1]
1 and 2 are views showing an internal combustion engine according to a first embodiment of the present invention. FIG. 1 shows a side view of one cylinder in the internal combustion engine 10 according to the first embodiment (hereinafter also simply referred to as “engine 10”) as viewed in the axial direction of the crankshaft, and a block diagram of the control device 50. . FIG. 2 is a perspective view showing four cylinders (that is, cylinders # 1 to # 4) of the in-line four-cylinder engine 10. The engine 10 according to the present embodiment is a diesel engine.

  As shown in FIG. 1, the engine 10 includes a cylinder 12. The cylinder 12 is formed in a cylinder block (not shown), and a piston 20 is provided therein. The upper part of the cylinder 12 is covered with a cylinder head (not shown), and a combustion chamber 26 is formed by the piston top surface and the cylinder head inner surface. The piston 20 is connected to the crankshaft 36 by a connecting rod 34.

  An in-cylinder fuel injection valve 28 and an in-cylinder pressure sensor 30 are provided above the cylinder 12. The in-cylinder fuel injection valve 28 injects the spray 32 made of fuel into the combustion chamber 26, so that the cylinder 12 reaches the combustion stroke. Combustion noise generated in the combustion stroke passes through the inside of the piston 20 from the top surface of the piston 20 as shown by a vibration 42 shown by a broken line, and reaches the crankshaft 36 via the connecting rod 34. As shown in FIG. 2, the vibrations 42 from the pistons 20 of the cylinders # 1 to # 4 reach the crankshaft 36, respectively.

  In the present embodiment, the engine 10 is a diesel engine, but the present invention is not limited to this and may be a gasoline engine. In that case, a cylinder head (not shown) is provided with an ignition plug and one or both of a port injection valve and an in-cylinder injection valve.

  A crankshaft timing rotor 38 is attached to the end of the crankshaft 36. The engine 10 includes a crank angle sensor 40. The crank angle sensor 40 can generate an output signal indicating a crank angle and a top dead center position by detecting a signal tooth 39 and a missing tooth portion (not shown) of the crankshaft timing rotor 38. The resolution of crank angle detection by the crank angle sensor 40 is preferably a high resolution of about 1 degree, for example.

  The engine 10 includes a control device 50. The control device 50 is an ECU (Electronic Control Unit), and includes a hardware configuration such as a CPU for performing arithmetic processing, a RAM, a ROM, and an input / output interface. The control device 50 is connected to various sensors such as an in-cylinder fuel injection valve 28, an in-cylinder pressure sensor 30, a crank angle sensor 40, an air flow meter (not shown), and an air-fuel ratio sensor (not shown). The control device 50 stores a program for calculating the fuel injection amount and fuel injection timing of the in-cylinder fuel injection valve 28 based on the output signals of the various sensors. The control device 50 detects the crank angle based on the output signal of the crank angle sensor 40.

  In the first embodiment and the second embodiment to be described later, the control device 50 calculates a function that defines a “relationship between the input and the engine control amount” or a “relationship between the input and the engine diagnosis result”. , Stored in the internal ROM. Here, the “function” widely means a function in which a correspondence relationship between an input value and an output value is determined in advance. That is, the “function” here includes a program for calculating a numerical value by numerical calculation, data storing a plurality of sets of input values and output values like a map, and the magnitude of the input value and a predetermined comparison value. A program that outputs a truth value or a logical value according to the relationship or the magnitude relationship of a plurality of input values is included. Further, the input value is not limited to one and may be plural. A value obtained by frequency analysis processing, which will be described later, is input to this function, and the engine 10 is controlled or diagnosed according to the engine control amount or diagnosis result output by this function.

[Control contents of the apparatus of the first embodiment]
3-5 is a figure for demonstrating the control content of the internal combustion engine concerning Embodiment 1 of this invention. FIG. 6 is a flowchart of a routine executed by the internal combustion engine according to the first embodiment of the present invention. Hereinafter, the control content of the control apparatus 50 is demonstrated using these figures.

  Of the spray 32, the spray component that diffuses perpendicularly to the combustion chamber 26 greatly contributes to the combustion noise. The vibration generated when the vertically diffused spray component burns is transmitted to the piston 20, the connecting rod 34, and the crankshaft 36. The transmitted vibration affects the magnitude of a specific frequency component included in the crank angular velocity detected by the crank angle sensor 40.

  Therefore, in the present embodiment, first, a frequency spectrum for a portion corresponding to the combustion stroke of the cylinder 12 in the output signal of the crank angle sensor 40 is obtained. Next, it is determined that the combustion noise is larger as the component of the predetermined frequency is larger in the frequency spectrum. This predetermined frequency is predetermined and stored in the memory of the control device 50 at the stage of designing, testing, etc. of the engine 10.

  For convenience, the frequency used for the combustion noise determination is referred to as a frequency fb. In the case of the engine 10, the frequency fb is a frequency corresponding to a secondary rotation order. The engine 10 according to the present embodiment is a four-stroke four-cylinder engine and generates combustion noise at a secondary rotational order. Therefore, if the magnitude of the frequency component corresponding to the secondary rotational order is evaluated, the magnitude of the combustion noise is obtained. Can be evaluated. For engines other than the four-cylinder engine, the frequency corresponding to the rotation order that is half the number of cylinders may be set to the frequency fb. For example, if the engine is 5 cylinders, the 2.5th order rotation order is used. What is necessary is just to evaluate the magnitude | size of the frequency component which corresponds to each.

  In actuality, the fuel injection timing may be retarded or advanced. Therefore, a frequency band of a predetermined width having a frequency corresponding to the secondary rotation order as a center frequency and spreading in the vicinity thereof is determined. It is preferable to use the magnitude of the frequency component included in the frequency band for determining combustion noise. For example, the maximum value of frequency components included in the frequency band may be used for combustion noise determination.

  In the routine of FIG. 6, first, the control device 50 executes a fuel injection amount acquisition process (step S100), a spray shape determination process (step S102), and a fuel injection timing acquisition process (step S104). A control target value calculated by the control device 50 may be used for the fuel injection amount and the fuel injection timing. The spray shape is determined by mechanical factors such as the nozzle direction of the in-cylinder fuel injection valve 28 and the intake port shape. Therefore, in the first embodiment, the information indicating the spray shape is stored in the control device 50 in advance.

  Next, the control apparatus 50 performs a piston position detection process (step S106). In this step, the position of the piston 20 when the in-cylinder fuel injection valve 28 injects fuel is calculated from the crank angle.

  Next, the control device 50 executes a combustion chamber distance estimation process (step S108). This “combustion chamber distance” is the distance between the tip of the injector of the in-cylinder fuel injection valve 28 and the top surface of the piston 20 in the cylinder 12. The combustion chamber distance can be calculated using the piston position during combustion detected in step S106 because the injector tip of the in-cylinder fuel injection valve 28 is determined when the engine 10 is designed.

  Next, the control device 50 executes combustion cylinder information acquisition processing (step S110). In this step, the timing at which combustion occurs in each of the cylinders # 1 to # 4 is associated with the output signal of the crank angle sensor 40. Since the combustion order of the engine 10 is determined, it is possible to specify which part of the output signal of the crank angle sensor 40 is near the combustion stroke of which cylinder. As shown in FIG. 2, the crankshaft 36 has a certain length. The distance between each of the cylinders # 1 to # 4 and the crankshaft timing rotor 38 is different for each cylinder number, and the cylinder # 1 is the closest and the cylinder # 4 is the farthest. Therefore, this cylinder number information may be included in the calculation of “noise transmission time” described later.

  Next, the control device 50 executes sampling processing and crank angular velocity acquisition processing (step S112). FIG. 3 is a diagram schematically illustrating a crank angular velocity waveform of the internal combustion engine according to the first embodiment of the present invention. The crank angular velocity is calculated from the crank angle value indicated by the output signal of the crank angle sensor 40. The crank angular velocity with the horizontal axis as the time axis has a waveform that peaks at a constant period as shown in FIG.

  In the crank angular velocity waveform shown in FIG. 3, there is a portion where more vibration due to combustion of each cylinder of the engine 10 appears. This portion is indicated by the symbol X in FIG. In the present embodiment, sampling is performed on the output signal of the crank angle sensor 40 so as to extract only a portion where a large amount of vibration due to combustion appears.

  The control device 50 changes the content of the sampling process for the crank angular velocity waveform obtained from the output signal of the crank angle sensor 40 according to which of the cylinders # 1 to # 4 is subjected to combustion noise detection. Specifically, the sampling process includes a sampling start timing ds, a sampling period Ts, and a sampling period Ws.

  FIG. 3 shows the sampling start timing ds, the sampling period Ts, and the sampling period Ws. The sampling interval Ws is the length of the sampling start point and end point, that is, the sampling width. The sampling period Ts is a period for performing sampling. The sampling start timing ds is an amount by which the start position of the sampling section Ws is delayed with reference to the angular velocity peak position in the crank angular velocity waveform.

  In the first embodiment, the sampling interval Ws is optimized using the following processing. As can be seen from the hardware diagrams of FIGS. 1 and 2, the top surface and main body of the piston 20, the connecting rod 34, and the crankshaft 36 are interposed in the path from the spray 32 to the crank angle sensor 40. It takes time until the crank angle sensor 40 detects the combustion noise of each of the cylinders # 1 to # 4 through this path. This time is also referred to as “noise transmission time”.

  When the noise transmission time is short, the angular velocity peak position in the crank angular velocity waveform shown in FIG. 3 approaches the portion where a lot of vibration due to combustion appears. Conversely, when the noise transmission time is long, the angular velocity peak position in the crank angular velocity waveform shown in FIG. 3 is separated from the portion where a lot of vibration due to combustion appears. It is preferable that the start position of the sampling section Ws with reference to the angular velocity peak position is largely delayed as the noise transmission time is longer. Therefore, the control device 50 increases or decreases the sampling start timing ds in conjunction with the noise transmission time.

  FIG. 4 is a map for calculating the noise transmission time of the internal combustion engine according to the first embodiment of the present invention. In the first embodiment, the noise transmission time is calculated from the diffusion speed of the spray 32 and the time for transmitting the piston 20, the connecting rod 34, etc. after combustion. Specifically, a map with the horizontal axis representing a function having the spray shape, the fuel injection amount, the fuel injection timing, and the above-described combustion chamber distance as parameters, and the noise transmission time defined on the vertical axis is created. Store in memory. The fuel injection amount and the spray shape are used for obtaining the diffusion speed of the spray 32. The slower the spray diffusion speed or the greater the above-mentioned combustion chamber distance, the greater the distance that the combustion noise is transmitted, and the longer the noise transmission time.

  The control device 50 increases or decreases the sampling start timing ds in conjunction with the noise transmission time acquired from the map shown in FIG. As described above, according to the first embodiment, the combustion noise in the cylinder 12 is based on the fuel injection amount into the cylinder 12, the fuel injection timing into the cylinder 12, and the position of the piston 20 in the cylinder 12. The start point of the sampling interval can be optimized in conjunction with the noise transmission time until the noise is transmitted to the crank angle sensor 40. As a result, the portion where the combustion noise appears in the output signal can be sampled with high accuracy.

  Next, the control device 50 performs frequency analysis processing on the signal acquired by the sampling processing in step S112 (step S114). In this step, a frequency analysis process for analyzing the frequency component included in the signal acquired by the sampling process is performed. Various techniques such as Fast Fourier Transform are already known as specific techniques for frequency analysis, and are not a new matter, so a description thereof is omitted here.

  FIG. 5 is a frequency spectrum obtained by frequency analysis of the internal combustion engine according to the first embodiment of the present invention. FIG. 5 is a power spectrum in which the horizontal axis represents the rotation order and the vertical axis represents the signal power.

  As described above, since the engine 10 is a four-stroke four-cylinder engine, combustion noise is generated at the second rotational order. Therefore, the magnitude of the frequency component corresponding to the secondary rotational order has a correlation with the magnitude of the combustion noise. The frequency fb in FIG. 5 is a frequency corresponding to the secondary rotation order. The value Pfb in FIG. 5 is a component at the frequency fb in the frequency spectrum, and increases as the combustion noise increases. In FIG. 5, what is surrounded by a solid line is a frequency component corresponding to the secondary rotation order in the frequency spectrum. On the other hand, in FIG. 5, what is surrounded by a broken line is a frequency component corresponding to a rotation order of less than the second order (that is, the first order or 1.5th order) in the frequency spectrum.

  Next, the control device 50 performs a filtering process for filtering a frequency component unrelated to the combustion noise and selectively extracting the value Pfb (step S116). A frequency component not related to combustion does not ride on a frequency component corresponding to the secondary rotation order. For example, it is known that misfire appears in a frequency component corresponding to a rotation order of 0.5th order, and engine friction and noise components appear in a frequency component corresponding to a rotation order of 3rd order or higher. Therefore, a band rejection filter process that does not pass a frequency component corresponding to a rotation order of 0.5th order or 3rd order or more may be applied to the frequency analysis result. Also, the resonance frequency of the engine 10 may be examined in advance, and the resonance frequency component may be attenuated by filtering.

  Next, the control device 50 executes a process for calculating a combustion noise index value (step S118). The combustion noise index value is an index value that is calculated to be larger as the combustion noise is larger. The control device 50 calculates a larger index value representing the magnitude of combustion noise as the value Pfb is larger. In this way, an index value that quantitatively represents the magnitude of combustion noise can be calculated from the output signal of the crank angle sensor 40.

  Thereafter, the current routine ends. According to the routine of FIG. 6 described above, the index value that quantitatively indicates the magnitude of the combustion noise using the magnitude of the value Pfb that is the frequency component corresponding to the combustion noise included in the output signal of the crank angle sensor 40 as an index. Can be calculated.

  In addition, without calculating the combustion noise index value, whether or not the combustion noise is abnormal may be determined alternatively according to whether or not the value Pfb exceeds the threshold value Pth. The routine of FIG. 6 can detect combustion noise using the output signal of the crank angle sensor 40, and does not use the output of the in-cylinder pressure sensor 30.

[Modification of Embodiment 1]
FIG. 7 is a flowchart of a routine executed by the control device for the internal combustion engine according to the modification of the first embodiment of the present invention. The routine of FIG. 7 differs from the routine of FIG. 6 in that steps S130 and S132 are provided instead of step S118.

  In step S130, control device 50 executes a process of determining whether value Pfb is equal to or greater than threshold value Pth. Specifically, if the determination result of Pfb ≧ Pth is true (true), the process proceeds to step S130. If the determination result of Pfb ≧ Pth is false (false), the combustion noise suppression control is started in step S130. The current routine ends without issuing a command to instruct.

  In step S132, a command for instructing the start of the combustion noise suppression control is issued, and the control device 50 executes the combustion noise suppression control. The combustion noise suppression control is to adjust various engine control amounts such as fuel injection timing so as to suppress the combustion noise. Various technologies are known for the combustion noise suppression control, and there are various engine control amounts that are adjusted to suppress the combustion noise as described below. For example, the technique disclosed in Japanese Patent Application Laid-Open No. 2005-315077 or Japanese Patent Application Laid-Open No. 2007-278175 may be used. For example, the combustion noise suppression control may retard the fuel injection timing as described in JP-A-2007-278175. Also, for example, in Japanese Patent Application Laid-Open No. 2005-315077, pilot injection is used as combustion noise suppression means for suppressing combustion noise in a combustion chamber, and combustion noise is arbitrarily controlled by controlling the presence, amount, and number of times. Techniques for controlling with timing and quantity are disclosed. Further, in JP-A-2005-315077, as other combustion noise suppression means, for example, selective reduction of the internal pressure of a delivery pipe by control of a high-pressure pump, variable nozzle type turbocharger (rotary blades of an exhaust side turbine) Selective reduction of supercharging pressure in vehicles equipped with a movable nozzle vane around and a supercharger with variable supercharging pressure), change of valve timing and valve lift amount by VVT control, gasoline engine, etc. It is also described that other means that can control the combustion conditions and any combination thereof can be used, such as changing the ignition timing in the case of an engine that is ignited by a spark plug.

  Thereafter, the current routine ends. According to the routine of FIG. 7 described above, focusing on the fact that the combustion noise component is added to the output signal of the crank angle sensor 40, the magnitude of the frequency component corresponding to the combustion noise included in the output signal of the crank angle sensor 40 is used as an index. Thus, the control for suppressing the combustion noise can be executed.

  As a modification of the routine of FIG. 7, in the combustion noise suppression control in step S132, the control device 50 may adjust the engine control amount so as to further suppress the combustion noise as the value Pfb increases. Accordingly, the engine control amount can be adjusted based on the output signal of the crank angle sensor 40 so as to reduce the combustion noise. Specifically, for example, as in the technique disclosed in Japanese Patent Application Laid-Open No. 2007-278175, the fuel injection timing may be delayed so that the combustion noise is reduced. Further, various engine control amounts in various combustion noise suppression means described in Japanese Patent Application Laid-Open No. 2005-315077 may be adjusted. A function that predetermines the relationship between the magnitude of combustion noise and various engine control amounts disclosed in the above-described known technology may be stored in the memory of the control device 50 in the form of a numerical calculation program or a map. In addition, by deleting step S130 from the routine of FIG. 7, the combustion noise suppression control in step S132 according to this modification may be performed constantly.

  In the first embodiment, the program in step S118 in the flowchart of FIG. 6 corresponds to “a function that defines the relationship between the input and the engine diagnosis result”. In the first embodiment, the process of step S130 and the program of S132 in the flowchart of FIG. 7 correspond to “a function that defines the relationship between the input and the engine control amount”.

Embodiment 2. FIG.
The control device for an internal combustion engine according to the second embodiment has the same hardware configuration as that of the first embodiment, and also has the same software processing executed by the control device. Therefore, in the following description, the difference between the first embodiment and the second embodiment will be mainly described, and the same reference numerals are given to the common configurations, and the description of the contents disclosed in common will be omitted. It shall be simplified.

  The main difference between the first embodiment and the second embodiment is that, in the second embodiment, the value of the combustion noise detected from the output signal of the in-cylinder pressure sensor 30 as well as the combustion noise detected from the output signal of the crank angle sensor 40 is different. It is to use together. Further, in the second embodiment, the control device 50 performs the combustion noise control described in step S132 of FIG. 7 using the combustion noise index value obtained from the output signal of the in-cylinder pressure sensor 30. To do.

  FIG. 8 is a flowchart of a routine executed by the control device for an internal combustion engine according to the second embodiment of the present invention. In the second embodiment, the control device 50 executes the routine of FIG.

  In the routine of FIG. 8, first, the control device 50 calculates the combustion noise index value CNcps calculated from the output signal of the in-cylinder pressure sensor 30 (step S200). The combustion noise index value CNcps is a parameter value having a correlation with the magnitude of the combustion noise. This combustion noise index value CNcps may be calculated based on, for example, dP / dt or dP / dθ, and various techniques for detecting combustion noise from the output signal of the in-cylinder pressure sensor 30 are already known. Since it is not a matter, explanation is omitted here.

  The “parameter values having a correlation with the magnitude of the combustion noise” calculated by these various known techniques are assumed to take various units, and are not necessarily the same unit as the following combustion noise index value CNcr. It is also assumed that this is not possible. In this case, the units may be matched by converting to a common unit (for example, decibel dB).

  Next, the control device 50 calculates the combustion noise index value CNcr calculated from the output signal of the crank angle sensor 40 (step S202). The combustion noise index value CNcr to be calculated in this step can be calculated by executing the routine according to FIG. 6 of the first embodiment described above.

Next, the control device 50 executes processing for determining whether or not a condition shown in the following equation (1) is satisfied (step S204).
| CNcps-CNcr | <CNth1 (1)

  CNth1 in Expression (1) is a correction threshold value for determining a decrease in the output of the in-cylinder pressure sensor 30. This correction threshold value is a threshold value for determining whether or not the sensitivity of the in-cylinder pressure sensor 30 tends to decrease. The accumulation of unburned components, soot, or HC in the sensor portion of the in-cylinder pressure sensor 30 may cause a problem that the sensitivity of the in-cylinder pressure sensor 30 is lowered and the reliability is lowered. Therefore, in the second embodiment, a decrease in sensitivity of the in-cylinder pressure sensor 30 is detected using this correction threshold value.

  When the condition of Expression (1) is not satisfied, the absolute value of the difference between CNcps and CNcr is less than the correction threshold value CNth1. In this case, the process returns to step S200.

When the condition of Expression (1) is satisfied, the absolute value of the difference between CNcps and CNcr is equal to or greater than the correction threshold value CNth1. In this case, the difference between CNcps and CNcr is so large that a decrease in sensitivity of the in-cylinder pressure sensor 30 is recognized. Therefore, in the second embodiment, a process for determining whether or not a condition shown in the following equation (2) is satisfied is executed (step S206).
| CNcps-CNcr | <CNth2 (2)
However, CNth1 <CNth2.

  CNth2 in the equation (2) is a failure threshold value for detecting a failure of the in-cylinder pressure sensor 30, and is set to a value larger than the correction threshold value.

When the condition of Expression (2) is satisfied, the absolute value of the difference between CNcps and CNcr is less than the threshold value CNth2. In this case, it can be determined that the in-cylinder pressure sensor 30 has a reduced sensitivity but has not failed. Therefore, in the second embodiment, the control device 50 executes a process of calculating the corrected index value CNcpsc according to the following equation (3) (step S208).
CNcps + CNcor = CNcpsc (3)
The correction value CNcor may be set in advance, may be a fixed value, or may be variable so as to increase in proportion to the difference between CNcps and CNcr.

  Thereafter, the routine returns to step S202, and steps S204 and S206 are sequentially executed again. Further, the control device 50 controls the engine 10 using the corrected index value CNcpsc calculated in step S208.

  On the other hand, when the condition of Expression (2) is satisfied, the absolute value of the difference between CNcps and CNcr is equal to or greater than threshold value CNth2. In this case, it can be determined that the sensitivity drop of the in-cylinder pressure sensor 30 is too great. Therefore, in this case, the control device 50 stops the combustion noise control performed using the combustion noise index value CNcps (step S210), and ends the current routine. The combustion noise control may be performed using various known techniques described in the first embodiment.

  According to the specific control according to the second embodiment described above, it is possible to determine whether or not the in-cylinder pressure sensor 30 has any abnormality such as a decrease in sensitivity or a failure. In addition, the change in output sensitivity of the in-cylinder pressure sensor 30 can be compensated based on the combustion noise obtained from the output signal of the crank angle sensor 40.

  In the second embodiment, on the assumption that the output of the crank angle sensor 40 is correct, it is determined whether or not the cylinder pressure sensor 30 has any abnormality such as a sensitivity drop or failure. However, the present invention is not limited to this. For example, when the absolute value of the difference between CNcps and CNcr is greater than or equal to the threshold value CNth2 in step S206, it may be determined in step S210 that both the crank angle sensor 40 and the in-cylinder pressure sensor 30 are abnormal. Alternatively, in contrast to the second embodiment, when the absolute value of the difference between CNcps and CNcr is equal to or greater than the threshold value CNth2, the output of the in-cylinder pressure sensor 30 is assumed to be correct, and the crank angle sensor 40 is set in step S210. It may be determined that there is some abnormality. By investigating the difference between the combustion noise obtained from the output signal of the crank angle sensor 40 and the combustion noise obtained from the output signal of the in-cylinder pressure sensor 30, it is diagnosed whether these sensors exhibit their original performance. can do.

  In the second embodiment, in addition to the above-described abnormality determination, the correction process in step S208 is performed so as to compensate for the change in output sensitivity of the in-cylinder pressure sensor 30 with the combustion noise index value CNcr as a reference. It is not limited. Of the routine shown in FIG. 8, the process of calculating the combustion noise correction value may not be performed, and only the abnormality determination of the in-cylinder pressure sensor 30 may be performed. Conversely, in the routine shown in FIG. 8, only the correction process may be performed without determining whether the in-cylinder pressure sensor 30 is abnormal.

  FIG. 9 is a flowchart of a routine executed by the control device for an internal combustion engine according to the modification of the second embodiment of the present invention. The processes included in FIGS. 8 and 9 are the same except that the process of step S220 is provided instead of step S210. Moreover, in this modification, the control apparatus 50 is connected to MIL (malfunction Indicator Light) for abnormality notification.

  In the routine of FIG. 9, when the absolute value of the difference between CNcps and CNcr is greater than or equal to threshold value CNth2 in step S206, control device 50 turns on MIL (step S220). Thereby, the result of the abnormality diagnosis can be recognized from the outside of the control device 50. Note that information transmission may be performed by an image, sound, or other method indicating abnormality notification instead of MIL lighting.

  In the second embodiment, the program in steps S206 and S210 in the flowchart of FIG. 8 corresponds to “a function that defines the relationship between the input and the engine diagnosis result”. Further, in the second embodiment, the program in step S206 and step S220 in the flowchart of FIG. 9 corresponds to “a function that defines the relationship between the input and the engine diagnosis result”.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Cylinder 20 Piston 26 Combustion chamber 28 In-cylinder fuel injection valve 30 In-cylinder pressure sensor 32 Spray 34 Connecting rod 36 Crankshaft 38 Crankshaft timing rotor 39 Signal tooth 40 Crank angle sensor 42 Vibration 50 Control device

Claims (9)

A crank angle sensor that is a sensor that emits an output signal corresponding to the rotation of a crankshaft connected to a piston provided in a cylinder of an internal combustion engine;
A function defining a relationship between the input and the control amount of the internal combustion engine or a relationship between the input and the diagnosis result of the internal combustion engine, and at least a portion corresponding to a combustion stroke of the cylinder of the output signal of the crank angle sensor The frequency analysis is performed on the internal combustion engine according to the control amount or the diagnosis result output by the function, and the value of the frequency component that increases as the combustion noise increases among the frequency components included in the portion is input to the function. A control device for controlling or diagnosing
An internal combustion engine comprising:   2. The internal combustion engine according to claim 1, wherein the function outputs the control amount so as to suppress combustion noise as the input value increases.   The internal combustion engine according to claim 1, wherein the function selectively outputs a signal instructing start of control for suppressing combustion noise in accordance with a magnitude of an input value.   The internal combustion engine according to any one of claims 1 to 3, wherein the function outputs a diagnosis result as to whether or not a combustion noise abnormality has occurred according to a magnitude of an input value. . A cylinder pressure sensor provided on the cylinder;
The control device calculates the value of the magnitude of combustion noise based on the output signal of the in-cylinder pressure sensor,
The function uses the magnitude value obtained from the output signal of the crank angle sensor as a first input, the combustion noise magnitude value obtained from the in-cylinder pressure sensor as a second input, and the first input. The diagnostic result that at least one of the crank angle sensor and the in-cylinder pressure sensor is abnormal is output according to the magnitude of the difference between the second input and the second input. An internal combustion engine according to claim 1. An in-cylinder pressure sensor provided in the cylinder;
An informing means for informing the abnormality of the internal combustion engine;
With
The control device calculates the value of the magnitude of combustion noise based on the output signal of the in-cylinder pressure sensor,
The function uses the magnitude value obtained from the output signal of the crank angle sensor as a first input, the combustion noise magnitude value obtained from the in-cylinder pressure sensor as a second input, and the first input. The internal combustion engine according to any one of claims 1 to 5, wherein a different signal is output to the notification means in accordance with a magnitude of a difference from the second input. A plurality of the cylinders are provided, and pistons of the cylinders are connected to a common crankshaft,
The control device inputs, into the function, a magnitude value of a frequency component corresponding to an order that is half the number of cylinders with respect to the engine speed during the combustion stroke, among the frequency components included in the portion. The internal combustion engine according to any one of claims 1 to 6.   The said control apparatus samples periodically the part away from the crank angular velocity peak position with respect to the output signal of the said crank angle sensor, and performs a frequency analysis with respect to the said sampled part. 8. The internal combustion engine according to any one of 7 above. The controller is
Noise transmission time until combustion noise in the cylinder is transmitted to the crank angle sensor based on the fuel injection amount to the cylinder, the fuel injection timing to the cylinder, and the position of the piston in the cylinder 9. The internal combustion engine according to claim 8, wherein a larger amount of the crank angular velocity peak position away from the portion where the sampling is performed is set to be longer as is longer.

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