JP6252201B2 - Abnormal combustion detector - Google Patents

Description

  The present invention relates to an abnormal combustion detection device configured to detect an abnormal combustion occurrence state in a spark ignition type internal combustion engine having an ignition plug.

  This type of device is known to be configured to detect the occurrence of knocking and pre-ignition based on the output of a vibration sensor (sometimes called a knock sensor) mounted on a cylinder block. (For example, refer to JP2013-160200A). In such a conventional apparatus, the knocking detection section and the pre-ignition detection section are set in different crank angle sections.

JP 2013-160200 A

  Knocking and preignition differ in the generation mechanism and the suppression method. For this reason, in this type of apparatus, it is required to make a good distinction between detection of occurrence of knocking and detection of occurrence of preignition. The present invention has been made in view of the circumstances exemplified above.

The present invention
An abnormal combustion detection device configured to detect an abnormal combustion occurrence state in a spark ignition internal combustion engine including an ignition plug,
A vibration sensor mounted on the cylinder block so as to output a signal having a waveform corresponding to vibration generated in the cylinder block of the internal combustion engine;
A crank angle sensor mounted on the internal combustion engine so as to output a signal corresponding to a rotation angle of a crankshaft provided in the internal combustion engine;
An ignition timing setting unit provided to set an ignition timing by the spark plug based on at least an operating state of the internal combustion engine;
An abnormal combustion detection processing unit provided to detect the occurrence state of the abnormal combustion based on outputs from the vibration sensor and the crank angle sensor;
With
The abnormal combustion detection processing unit
A section provided to set a first detection section that is a detection section of knocking as the abnormal combustion and a second detection section that is a detection section of preignition as the abnormal combustion in different crank angle sections. It has a setting part,
The section setting section sets the second detection section based on the ignition timing set by the ignition timing setting section.

  In the abnormal combustion detection apparatus of the present invention having such a configuration, the section setting unit may use different cranks for the first detection section that is a knocking detection section and the second detection section that is a pre-ignition detection section. Set in the corner section. In the first detection section, a knocking occurrence state is mainly detected based on outputs from the vibration sensor and the crank angle sensor. On the other hand, in the second detection section, a pre-ignition occurrence state is mainly detected based on outputs from the vibration sensor and the crank angle sensor.

  By the way, pre-ignition means that the air-fuel mixture reaches self-ignition in the combustion chamber before the normal (target) ignition timing, as is well known. For this reason, there is some correlation between the occurrence timing of pre-ignition and the ignition timing set by the ignition timing setting unit. That is, for example, when the ignition timing is advanced, preignition is induced due to an increase in the temperature of the spark plug (this is due to an increase in the thermal load on the spark plug).

  Therefore, in the abnormal combustion detection device of the present invention, the section setting unit sets the second detection section, which is a pre-ignition detection section, based on the ignition timing set by the ignition timing setting section. As a result, it is possible to distinguish between detection of occurrence of knocking and detection of occurrence of preignition even better than before.

The figure which shows schematic structure of the internal combustion engine which is an example of the application object of this invention. The functional block diagram of one Embodiment of the abnormal combustion detection apparatus of this invention implement | achieved by ECU etc. which are shown by FIG. The time chart which shows the specific example of the setting aspect of the detection area by the area setting part shown by FIG. The time chart which shows the specific example of the setting aspect of the detection area by the area setting part shown by FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In addition, since a modification will prevent understanding of description of one consistent embodiment, if it is inserted during the description of the said embodiment, it is described collectively at the end.

<Overall system configuration>
Referring to FIG. 1, an engine 10 that is a spark ignition type internal combustion engine includes a cylinder block 11 and a cylinder head 12. At least one cylinder 13 is formed inside the cylinder block 11. A piston 14 is accommodated in the cylinder 13 so as to be reciprocally movable. A combustion chamber is formed by the top dead center side (upper side in the drawing) of the space inside the cylinder 13.

  A crankshaft 15 is rotatably supported at the bottom of an engine block (including the cylinder block 11 described above) that constitutes the main body of the engine 10. The crankshaft 15 is connected to the piston 14 via a connecting rod 16 or the like. A water jacket 17 is formed in the cylinder block 11. The water jacket 17 is a space through which a coolant (hereinafter abbreviated as “coolant”: specifically, coolant) can flow, and is provided so as to surround the cylinder 13 from the side of the cylinder 13.

  An intake port 18 and an exhaust port 19 are formed in the cylinder head 12 so as to communicate with the cylinder 13. Further, the cylinder head 12 is provided with a known valve driving mechanism having an intake valve 21, an exhaust valve 22, and a variable valve mechanism 23. The intake valve 21 is provided so as to control the communication state between the intake port 18 and the cylinder 13. Similarly, the exhaust valve 22 is provided so as to control the communication state between the exhaust port 19 and the cylinder 13. The variable valve mechanism 23 is configured to be able to set the opening / closing timing of the intake valve 21 to a desired timing by controlling the operation state of the hydraulic actuator 24.

  The cylinder head 12 is provided with an injector 25, a spark plug 26, and an ignition device 27. The injector 25 is provided so as to inject fuel to be supplied into the cylinder 13. The spark plug 26 is provided such that a counter electrode portion for generating spark discharge for igniting the air-fuel mixture is exposed in the cylinder 13 (combustion chamber). The ignition device 27 includes an ignition coil, an igniter, and the like, and is provided so that the spark plug 26 generates the above-described spark discharge based on the input ignition signal.

  An intake pipe 31 is connected to the intake port 18. An intake manifold 32 and a surge tank 33 are provided at a position downstream of the intake pipe 31 in the intake flow direction. The intake manifold 32 is provided in the most downstream portion of the intake pipe 31 in the intake flow direction, and is connected to the intake port 18. The surge tank 33 is provided upstream of the intake manifold 32 in the intake air flow direction.

  A throttle valve 34 is interposed in the intake pipe 31. The throttle valve 34 is a means for adjusting the amount of gas (air) sucked into the cylinder 13 and is provided upstream of the surge tank 33 in the intake air flow direction. The opening of the throttle valve 34 is adjusted by a throttle actuator 35 such as a DC motor.

  A turbocharger 36 is provided upstream of the throttle valve 34 in the intake air flow direction. In the present embodiment, the supercharger 36 is a so-called “turbocharger” driven by exhaust gas flowing through the exhaust pipe 37 so as to supercharge intake air by using the energy of the exhaust gas. It is configured.

<Schematic configuration of engine control device>
The engine control device 50 constituting the “abnormal combustion detection device” of the present invention appropriately detects an operating state and an abnormal state (including an abnormal combustion state in the cylinder 13) in the engine 10 and a vehicle equipped with the engine 10. However, the operation of the engine 10 is controlled based on the detection result. Specifically, the engine control device 50 is configured so that each part of the engine 10 (hydraulic actuator 24, injector 25, ignition device 27, throttle, etc.) in response to inputs from various sensors (main components will be described later), switches, and the like. Actuator 35, etc.) is configured to control the operation. Hereinafter, details of the configuration of the engine control device 50 will be described.

  The engine control device 50 includes an ECU 51. The ECU 51 is connected to each part of the engine 10 described above and sensors described later so as to be able to exchange signals. The ECU 51 also includes a microcomputer 52. The microcomputer 52 executes various control programs (routines) while using various information obtained based on inputs from sensors and the like to be described later, thereby controlling the driving of each part of the engine 10 described above. It is provided to generate a drive control signal. Details of the configurations of the ECU 51 and the microcomputer 52 will be described later.

  The engine control device 50 includes an air flow meter 53, an intake air temperature sensor 54, a crank angle sensor 55, a coolant temperature sensor 56, and a vibration sensor 57.

  The air flow meter 53 and the intake air temperature sensor 54 are attached to the intake pipe 31 at a position upstream of the throttle valve 34 in the intake air flow direction. The air flow meter 53 is provided so as to generate an output corresponding to the intake air amount Ga (the mass flow rate of the intake air introduced into the cylinder 13 through the intake pipe 31). The intake air temperature sensor 54 is provided so as to generate an output corresponding to the intake air temperature THa (temperature of intake air flowing through the intake pipe 31).

  The crank angle sensor 55 is mounted on the engine block described above so as to face the crankshaft 15. The crank angle sensor 55 is provided so as to output a signal corresponding to the rotation angle of the crankshaft 15, that is, the engine speed Ne. Specifically, the crank angle sensor 55 is configured to output a signal having a narrow pulse every time the crankshaft 15 rotates 10 degrees and a wide pulse every time the crankshaft 15 rotates 360 degrees.

  The coolant temperature sensor 56 and the vibration sensor 57 are mounted on the cylinder block 11. The coolant temperature sensor 56 is provided so as to generate an output corresponding to the coolant temperature THw (the temperature of the coolant flowing through the water jacket 17). The vibration sensor 57 is provided so as to output a signal having a waveform corresponding to the vibration generated in the cylinder block 11 and propagating through the cylinder block 11.

  Referring to FIG. 2, the ECU 51 includes an interface 511. The interface 511 is provided between the above-described various sensors and parts of the engine 10 and the microcomputer 52. That is, the microcomputer 52 is connected to the above-described various sensors and each part of the engine 10 through the interface 511 so as to be able to exchange signals.

  In particular, the vibration sensor 57 is connected to the interface 511 via the filter 512 and the peak hold circuit 513. The filter 512 is a so-called band-pass filter, and is provided so as to pass the output signal of the vibration sensor 57 in the frequency band set under the control of the microcomputer 52. The peak hold circuit 513 is provided to detect and output a peak value in the output signal of the vibration sensor 57 that has been bandpass processed by the filter 512. Since the vibration sensor 57, the filter 512, and the peak hold circuit 513 are well known, further detailed description thereof will be omitted in this specification (for example, Japanese Patent Laid-Open No. 9-32623 as necessary). (See US Pat. No. 5,811,667).

  The microcomputer 52 includes a ROM 521, a RAM 522, and a CPU 523. The ROM 521 stores in advance the above-described control program and a map (lookup table) that is referred to when the control program is executed. The RAM 522 is provided so that data can be temporarily stored when the CPU 523 executes the control program described above. The CPU 523 generates and outputs the above-described drive control signal by executing the above-described control program while using various information obtained based on inputs from the above-described sensors and the like.

  In the CPU 523 in FIG. 2, functional blocks realized by executing a control program related to abnormal combustion detection according to the present embodiment are shown. Specifically, an ignition timing setting unit 523a and an abnormal combustion detection processing unit 523b are provided in the CPU 523.

  The ignition timing setting unit 523a performs abnormal combustion on the target ignition timing SAt set based on the ignition timing map Map_SA (Ne, L) using the load L calculated from the intake air amount Ga and the engine speed Ne as parameters. By providing feedback control according to the detection result of the abnormal combustion occurrence state by the detection processing unit 523b, a command ignition timing SAc (hereinafter simply referred to as “ignition timing SA”) is set. The abnormal combustion detection processing unit 523b is provided to detect an abnormal combustion occurrence state based on outputs from the crank angle sensor 55 and the vibration sensor 57.

  The abnormal combustion detection processing unit 523b includes a section setting unit 523b1 and a determination unit 523b2. The section setting unit 523b1 divides the first detection section D1 that is the detection section of knocking as abnormal combustion and the second detection section D2 that is the detection section of preignition as the abnormal combustion into different crank angle sections (but both Can be overlapped). The determination unit 523b2 corresponds to the detection section (D1, D2) set by the section setting unit 523b1, and the abnormal combustion occurrence state based on the output of the vibration sensor 57 (specifically, the output of the peak hold circuit 513). Is provided to detect

  In the present embodiment, the section setting unit 523b1 sets the second detection section D2 based on the ignition timing SA. Specifically, the section setting unit 523b1 sets the start period D2st and / or the end period D2ed in the second detection section D2 with reference to the ignition timing SA. In particular, in the present embodiment, the section setting unit 523b1 sets the interval between the start period D2st and / or the end period D2ed and the ignition timing SA based on the operating state of the engine 10.

<Action and effect>
Hereinafter, the operation and effect of the configuration of the present embodiment will be described with reference to the time charts of FIGS. 3 and 4 in addition to FIGS. 1 and 2 as appropriate.

  The engine control device 50 of this embodiment is disclosed in Japanese Patent Application Laid-Open No. 8-319931 (US Pat. No. 5,632,247, European Patent Application Publication No. 1098184) or Japanese Patent Application Laid-Open No. 2013-142333 (US Pat. Similar to the configuration disclosed in Japanese Patent Application Publication No. 2013/0179052), a detection section for detecting knocking (first detection section D1) and a detection section for detecting preignition (second outgoing section) By setting D2) in different sections (crank angle sections), knocking and pre-ignition are individually detected using the common vibration sensor 57.

  That is, in the first detection section D1, the occurrence of knocking is mainly detected based on the outputs from the crank angle sensor 55 and the vibration sensor 57. On the other hand, in the second detection section D2, the pre-ignition occurrence state is mainly detected based on the outputs from the crank angle sensor 55 and the vibration sensor 57.

  By the way, pre-ignition means that the air-fuel mixture reaches self-ignition in the combustion chamber before the ignition timing SA, as is well known. Therefore, there is some correlation between the pre-ignition occurrence timing and the ignition timing SA. That is, for example, when the ignition timing SA is advanced, preignition is induced due to a rise in the temperature of the spark plug 26 (this is due to an increase in the thermal load on the spark plug 26). Therefore, the section setting unit 523b1 sets the second detection section D2, which is a pre-ignition detection section, based on the ignition timing SA set by the ignition timing setting section 523a.

  In this specific example, the start period D1st in the first detection section D1 is set based on a map Map_D1st (SA) using the ignition timing SA as a parameter. On the other hand, the final period D1ed in the first detection section D1 is set after a predetermined crank angle (interval D1int [CA]: constant value) from the initial period D1st.

The start period D2st in the second detection section D2 is set in advance to a predetermined crank angle (for example, BTDC 20 ° CA). On the other hand, the end period D2ed in the second detection section D2 is set based on the ignition timing SA and the interval ΔC between the end period D2ed and the ignition timing SA. Specifically, the interval ΔC and the end period D2ed are calculated by the following equations. In this case, the interval D2int [CA] of the second detection section D2 becomes variable as the ignition timing SA varies based on the operating state of the engine 10.
ΔC = Map_ΔC (Ne, L) · Map_K (THa, THw) (1)
D2ed = SA−ΔC (2)

  3 shows a case where ΔC ≧ 0, and FIG. 4 shows a case where ΔC <0. The pre-ignition usually occurs before the ignition timing SA. For this reason, as shown in FIG. 4, it is possible to satisfactorily distinguish between detection of occurrence of knocking and detection of occurrence of preignition by providing the preignition detection section before the ignition timing SA. It becomes.

  However, the preignition occurrence timing may be slightly delayed depending on the presence state of the “fire type” (floating matter in the cylinder or the like) that is the trigger for the occurrence of preignition. For this reason, normally, as shown in FIG. 3, the end period D2ed of the second detection section D2, which is the pre-ignition detection section, is set slightly after the ignition timing SA (ΔC ≧ 0). However, when the pre-ignition occurrence timing is only an early timing due to the specifications of the engine 10 (for example, supercharging pressure setting, etc.), the distinction between knocking occurrence detection and pre-ignition occurrence detection is made. In order to further improve the condition, the end period D2ed of the second detection interval D2 may be set before the ignition timing SA as shown in FIG. 4 (ΔC <0).

  As described in detail above, according to the configuration of the present embodiment, it is possible to better distinguish between detection of occurrence of knocking and detection of occurrence of preignition than before.

  In particular, in recent years, so-called “supercharged downsize”, in which the supercharger 36 is provided while reducing the displacement of the engine 10 in order to improve fuel efficiency, has been attracting attention. In such a supercharged downsize configuration, the occurrence of pre-ignition can be a particular problem. In addition, the pre-ignition occurrence timing may vary due to changes in fuel properties (particularly octane number), aging degradation of the engine 10 and the like. In this regard, according to the configuration of this embodiment, even in such a supercharged downsize configuration, it is possible to distinguish between occurrence detection of knocking and detection of occurrence of pre-ignition with higher accuracy than in the past. .

<Modification>
Hereinafter, some typical modifications will be exemplified. In the following description of the modified examples, the same reference numerals as those in the above embodiment can be used for portions having the same configurations and functions as those described in the above embodiment. And about description of this part, the description in the above-mentioned embodiment shall be used suitably in the range which is not technically consistent. Needless to say, the modifications are not limited to those listed below. In addition, a part of the above-described embodiment and all or a part of the plurality of modified examples can be combined appropriately as long as they are technically consistent.

  The present invention is not limited to the specific apparatus configuration and operation (control) mode described above. For example, the supercharger 36 may be an electric supercharger, a so-called electric assist turbocharger, or a so-called supercharger that is driven by the rotational driving force of the crankshaft 15. Good. Furthermore, a plurality of superchargers 36 may be interposed in the intake pipe 31. In addition, according to this invention, it is natural that a favorable effect is acquired also in the structure which is not provided with the supercharger 36. FIG.

  The microcomputer 52 may include a nonvolatile memory (for example, flash memory or EEPROM (registered trademark)) that can be rewritten when energized. In this case, the above-described control program, a map (lookup table) referred to when executing the control program, and the like may be stored in the nonvolatile memory. Alternatively, such a nonvolatile memory may be used as the ROM 521 described above.

  In calculating the load L, the opening degree of the throttle valve 34 and / or the accelerator pedal operation amount may be used instead of or together with the intake air amount Ga. In setting the target ignition timing SAt, other parameters may be used instead of or in addition to the load L. The same applies to the engine speed Ne.

  The target ignition timing SAt may be used instead of the above-described command ignition timing SAc as the ignition timing SA used when setting the section in the section setting unit 523b1.

  The start period D2st in the second detection section D2 may also be set variably based on the operating state of the engine 10 and the like, as in the specific example described above. The same applies to the end period D1ed in the first detection section D1. Alternatively, the first detection section D1 may be a predetermined crank angle section (for example, TDC to ATDC 90 ° CA) regardless of the operating state of the engine 10 or the like.

  Instead of the final period D2ed in the second detection section D2, the interval D2int may be set based on the ignition timing SA. In this case, the start period D2st in the second detection section D2 is set in advance to a predetermined crank angle (for example, BTDC 20 ° CA) as in the above-described specific example. The same applies to the interval D1int in the first detection section D1. In this case, the final period D1ed in the first detection section D1 is set in advance to a predetermined crank angle (for example, BTDC 90 ° CA).

  Other modifications not specifically mentioned are naturally included in the technical scope of the present invention without departing from the essential part of the present invention. In addition, in each element constituting the means for solving the problems of the present invention, elements expressed in terms of function and function are specific configurations disclosed in the above-described embodiments and modifications, and equivalents thereof. In addition to objects, any configuration capable of realizing the action / function is included. Furthermore, corresponding to the points where the description of the known or well-known technical matters is omitted, the description (including the specification and drawings) of each publication cited in this specification is intended to supplement the omitted description. As long as there is no technical contradiction, it can be used as appropriate as a part of this specification.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Cylinder block, 13 ... Cylinder, 15 ... Crankshaft, 26 ... Spark plug, 27 ... Ignition device, 36 ... Supercharger, 50 ... Engine control device, 51 ... ECU, 52 ... Microcomputer, 53 ... Air flow meter, 54 ... Intake air temperature sensor, 55 ... Crank angle sensor, 56 ... Cooling water temperature sensor, 57 ... Vibration sensor, 523 ... CPU, 523a ... Ignition timing setting unit, 523b ... Abnormal combustion detection processing unit, 523b1 ... Section setting Part, 523b2 ... determining part, D1 ... first detection section, D1ed ... end, D1int ... interval, D1st ... start, D2 ... second detection section, D2ed ... end, D2int ... interval, D2st ... start.

Claims (3)

An abnormal combustion detection device (50) configured to detect an abnormal combustion occurrence state in a spark ignition internal combustion engine (10) provided with an ignition plug (26),
A vibration sensor (57) attached to the cylinder block so as to output a signal having a waveform corresponding to vibration generated in the cylinder block (11) of the internal combustion engine;
A crank angle sensor (55) attached to the internal combustion engine so as to output a signal corresponding to a rotation angle of a crankshaft (15) provided in the internal combustion engine;
An ignition timing setting section (523a) provided to set an ignition timing by the spark plug based on at least an operating state of the internal combustion engine;
An abnormal combustion detection processing unit (523b) provided to detect the occurrence state of the abnormal combustion based on outputs from the vibration sensor and the crank angle sensor;
With
The abnormal combustion detection processing unit
A section provided to set a first detection section that is a detection section of knocking as the abnormal combustion and a second detection section that is a detection section of preignition as the abnormal combustion in different crank angle sections. A setting unit (523b1),
The section setting unit
Based on the ignition timing set by the ignition timing setting unit, is configured to set the second detection interval ,
When setting the second detection section, with the ignition timing as a reference, setting the start and / or end in the second detection section,
An abnormal combustion detection device that sets an interval between the final stage and the ignition timing based on an operating state of the internal combustion engine.   An abnormal combustion detection device (50) configured to detect an abnormal combustion occurrence state in a spark ignition internal combustion engine (10) provided with an ignition plug (26),
  A vibration sensor (57) attached to the cylinder block so as to output a signal having a waveform corresponding to vibration generated in the cylinder block (11) of the internal combustion engine;
  A crank angle sensor (55) attached to the internal combustion engine so as to output a signal corresponding to a rotation angle of a crankshaft (15) provided in the internal combustion engine;
  An ignition timing setting section (523a) provided to set an ignition timing by the spark plug based on at least an operating state of the internal combustion engine;
  An abnormal combustion detection processing unit (523b) provided to detect the occurrence state of the abnormal combustion based on outputs from the vibration sensor and the crank angle sensor;
  With
  The abnormal combustion detection processing unit
  A section provided to set a first detection section that is a detection section of knocking as the abnormal combustion and a second detection section that is a detection section of preignition as the abnormal combustion in different crank angle sections. A setting unit (523b1),
  The section setting unit
  Based on the ignition timing set by the ignition timing setting unit, is configured to set the second detection interval,
  When setting the second detection section, with the ignition timing as a reference, setting the start and / or end in the second detection section,
  An abnormal combustion detection device that sets an interval between the start timing and the ignition timing based on an operating state of the internal combustion engine. The abnormal combustion detection device according to claim 1 or 2 ,
The abnormal combustion detection device, wherein the internal combustion engine is a supercharged internal combustion engine.

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