JP4946900B2 - Combustion control device and engine control system for compression ignition type cylinder injection engine - Google Patents

Description

  The present invention is applied to an engine system including a compression ignition engine and a fuel injection valve for in-cylinder injection, and controls the combustion of a compression ignition in-cylinder injection engine that controls the operation of at least one actuator in the system. And an engine control system.

  As is well known, for example, an engine (particularly an internal combustion engine) used as a power source of an automobile or the like ignites and burns fuel supplied by an appropriate fuel injection valve (injector) in a combustion chamber in a predetermined cylinder. Thus, torque (power) is generated on a predetermined output shaft (crankshaft). In recent years, in diesel engines for automobiles, etc., sub-injection with a smaller injection amount (usually minute amount) than the main injection before or after performing main injection for generating output torque in one combustion cycle The so-called multi-stage injection method has been adopted. For example, today, noise during fuel combustion and an increase in NOx emission amount are regarded as problems, and for the improvement, pilot injection and pre-injection may be performed with a small injection amount before main injection. In addition, after the main injection, after-injection (injection timing is during fuel combustion close to the main injection) or activation of the exhaust temperature is performed for the purpose of activating diffusion combustion and thus reducing PM emission. In some cases, post-injection (the injection timing is after the end of combustion, which is greatly retarded with respect to the main injection), for the purpose of activating the catalyst by supplying a reducing component, or the like. In recent engine control, the fuel is supplied to the engine in one or any combination of these various injections in an injection mode (injection pattern) more suitable for various situations.

  However, in such a multi-stage injection system, the sub-injection is performed in a minute amount, and thus is easily affected by environmental conditions. For example, in unstable combustion such as PCCI combustion or HCCI combustion, the combustion amount of fuel injected by pilot injection (pilot combustion amount) is likely to change. For example, the pilot combustion amount fluctuates due to being influenced by disturbance (change in fuel properties, intake air temperature, etc.). When such a variation in the pilot combustion amount occurs, it also affects the combustion characteristics (main combustion amount, main combustion timing, etc.) of the fuel injected by the main injection. For this reason, when performing multi-stage injection control, an error (deviation) tends to occur in the combustion characteristics of the main combustion. When such an error in combustion characteristics occurs, there is a concern about deterioration of emission and instability of the combustion state.

Therefore, conventionally, as described in Patent Document 1, for example, an in-cylinder pressure sensor (CPS) that outputs a detection signal corresponding to the pressure in the combustion chamber (in-cylinder pressure) is used to detect the main fuel injected by main injection. An apparatus that calculates (detects) a main ignition timing (combustion start timing) that is an ignition timing has also been proposed. In this device, in-cylinder pressure during engine operation is measured by a cylinder pressure sensor for a diesel engine (compression ignition type cylinder injection engine), and in detail, the cylinder pressure and heat are measured based on the sensor output. The main ignition timing is detected by utilizing the correlation between the occurrence rate and the occurrence rate. Then, the parameter that acts on the main ignition timing, that is, the command value of the main injection execution timing for the fuel injection valve for in-cylinder injection, is varied so as to reduce the deviation between the detected value of the main ignition timing and the target value from time to time. By setting, feedback control of the occasional main ignition timing to a desired value is performed.
JP 2004-1000055 A

  FIG. 17 shows the combustion characteristics (transition of the heat generation rate) of the main injection obtained by the inventor through experiments and the like for the apparatus described in Patent Document 1. In FIG. 17, (a) shows the transition of the injection command (pulse signal whose pulse width corresponds to the injection time) for the fuel injection valve, and (b) shows the unit crank angle generated by burning the fuel. It is a timing chart which shows transition of the heat release rate which is the amount of heat per (unit output shaft rotation angle), respectively.

  As shown in FIG. 17, the main ignition timing that is the ignition timing (combustion start timing) of the main fuel injected by the main injection (eg, the heat generation rate is positive in the vicinity of the fuel injection timing in the waveform of the heat generation rate). (Which can be detected as the timing of sudden change) changes depending on fuel properties (for example, cetane number in light oil fuel). Specifically, under conditions where the combustion chamber temperature is relatively low, such as a low load, for example, the low cetane number fuel indicated by the two-dot chain line L51b in the figure is higher than the high cetane number fuel indicated by the one-dot chain line L51a in the figure. However, the ignition delay time is longer and the heat generation rate is lower. This is because the time required for fuel ignition is longer for low cetane fuel than for high cetane fuel, and the combustion rate (ease of combustion) Is equivalent to higher cetane number fuel than low cetane number fuel. As a result, in the case of a low cetane number fuel, in addition to the ignitability of the fuel itself, the amount of heat generated by pilot injection is less than that in the case of a high cetane number fuel, and consequently in the cylinder (strictly, the combustion chamber) This atmosphere is more difficult to ignite than in the case of a high cetane fuel. For this reason, in the case of low cetane number fuel, the ignition timing of combustion by main injection (main ignition timing) becomes timing t50b later than timing t50 in the case of high cetane number fuel. Also, the time from pilot fuel ignition (timing t50a) to main fuel ignition (timing t50b) (interval between both timings), and from the start (start) of main injection to the start of combustion (ignition) Both of these times (main ignition delay times) are longer than in the case of the high cetane number fuel. As the main ignition delay time becomes longer, the pressure in the combustion chamber (in-cylinder pressure), and thus the combustion rate (ease of combustion) at the main ignition timing decreases, and the maximum heat generation rate (for example, heat This can also be detected as a maximum point in the vicinity of the main ignition timing in the occurrence rate waveform) as compared to the case of high cetane number fuel.

  Thus, normally, the lower the cetane number, the lower the maximum heat generation rate related to the main injection. Therefore, when a fuel having a cetane number that is too low is used, a sufficient combustion amount (heat generation rate) and thus a sufficient torque cannot be obtained by the main injection. As a result, there is a concern about the deterioration of emissions (white smoke generation due to an increase in the amount of HC generated), the deterioration of drivability (drivability), etc., and worsening will result in misfire.

  Therefore, the inventor performs feedback control of the main ignition timing based on the variable setting of the main injection execution timing (injection start timing) using the apparatus described in Patent Document 1, and the main ignition is performed even in the case of low cetane number fuel. The timing is controlled to be as early as the timing for the high cetane fuel (timing t50 in FIG. 17). Specifically, a command value (for example, FIG. 17) related to the main injection execution timing is set so that the detection value (the timing t50b) of the main ignition timing obtained from the output of the in-cylinder pressure sensor is the timing t50 on the more advanced side. (Pulse signal shown in (a)) is corrected to a timing t52 on the advance side of the timing t51 before correction. By doing so, the main ignition timing can be controlled at the timing t50 even in the case of low cetane number fuel (solid line L52 in FIG. 17). When correcting the main injection execution timing (strictly, its command value), the pilot injection execution timing corresponding to the change (correction) of the main injection execution timing is used, for example, the interval between both injections is set. The timing is changed (corrected) to a more advanced timing so as to maintain a constant (or predetermined interval).

  However, even when the above control (feedback control of the main ignition timing) is performed on the low cetane number fuel, the combustion rate is not sufficiently increased by the pilot injection, so that the main ignition is higher than the case of the high cetane number fuel. There will be no change in the delay time. For this reason, if the execution timing (injection start timing) of the main injection is made too early, a large amount of fuel that has been injected from the start of the main injection together with the unburned fuel of the pilot injection to the solid line L52 in FIG. As shown in the figure, there is a possibility that ignition and combustion will occur at a stroke at the main ignition timing (timing t50 in FIG. 17), and excessive heat generation, and thus excessive increase in in-cylinder pressure may occur. If an excessive increase in in-cylinder pressure occurs, noise or vibration is generated, or an impact exceeding the mechanical strength is given to the cylinder where the fuel is burned. If worse, there is a concern that the life of the cylinder may be reduced or it may be damaged.

  The present invention has been made in view of such circumstances, and is a compression ignition type in-cylinder injection engine that can improve the combustion characteristics of an internal combustion engine, particularly the combustion characteristics related to the main ignition timing of the main fuel supplied by the main injection. The main object is to provide a combustion control device and an engine control system.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

In the first configuration , a compression ignition type engine (internal combustion engine) that ignites and burns fuel based on compression in a combustion chamber in a cylinder and generates power (for example, torque) on an output shaft by the combustion, and the combustion chamber Combustion control of a compression ignition type in-cylinder injection engine that is applied to an engine system that includes a fuel injection valve for in-cylinder injection that directly injects the fuel into the system and that controls the operation of at least one actuator in the system In the apparatus, the main ignition timing which is the ignition timing (combustion start timing) of the main fuel injected by the main injection for mainly generating power on the output shaft, or a parameter (for example, per predetermined time) Ignition timing detection means for detecting a predetermined point in the waveform of the heat generation rate that is the amount of generated heat), and detection by the ignition timing detection means A command value for the main injection execution timing for the fuel injection valve in a direction toward a value that falls within a predetermined range (for example, a fixed range or a range that is variably set according to the engine operating state at that time). A first correction unit that corrects one command value and whether or not the first command value corrected by the first correction unit is within a first allowable range that is a predetermined range (for example, the first command value) A determination unit that determines the value itself or a parameter value that changes according to the first command value), and the determination unit determines that the first command value is not within the first allowable range. With respect to one command value and the first permissible range, the ignition timing detecting means depends on whether the first command value is on the slow side (so-called retard side) or the fast side (so-called advance side) of the first permissible range. The detected value by Among command values for actuators in the system so as to move to the side (so-called retard side) or the fast side (so-called advance side), a predetermined command value (one type of command value) other than the first command value Or a plurality of types of command values), a second correction unit that corrects the second command value.

The inventor corrects not only the command value (first command value) of the main injection timing for the fuel injection valve but also a predetermined command value (second command value) other than the command value among the command values for the actuator in the system. Then, by controlling the main ignition timing, it was found that the main injection timing by the fuel injection valve can be within a range (first permissible range) in which the above-described inconvenience such as noise does not occur, and invented the apparatus. That is, with such a configuration, for example, the main injection timing is advanced too early (or too late) to advance (or delay) the main ignition timing, and the first command value falls within the first allowable range by the determination means. If it is determined that there is no difference (excessive deviation from the assumed position), the main ignition timing can be variably controlled in the same direction as the deviation direction of the main injection timing according to other parameters. It becomes possible. Then, by performing auxiliary control based on these other parameters, the main injection timing by the fuel injection valve can be returned to the allowable range. Thus, according to the apparatus of the first configuration , it is possible to control the main ignition timing while keeping the main injection timing by the fuel injection valve in the vicinity of the predetermined range (first allowable range), As a result, the combustion characteristics of the internal combustion engine, particularly the combustion characteristics related to the main ignition timing of the main fuel supplied by the main injection can be improved.

In this case, in particular, as in the second configuration, a series of processes such as the correction process by the first correction unit and the determination process by the determination unit are performed under predetermined conditions (for example, always during engine operation). It is effective to have a configuration that includes means for repeating while it is established. By doing so, every time the first command value (corresponding to the main injection timing by the fuel injection valve) goes out of the first allowable range, the command value is returned to the first allowable range. That is, according to such a configuration, the main injection timing by the fuel injection valve is automatically converged within a predetermined allowable range.

With regard to such a configuration, as in the third configuration , each time the second correction unit determines that the first command value is not within the first allowable range by the determination unit, the second command value It is effective to adopt a configuration in which is changed cumulatively by a predetermined change amount (for example, a fixed value or a variable value according to a predetermined parameter). By doing so, it becomes possible to accurately converge the main injection timing by the fuel injection valve within a predetermined allowable range.

Further, as in the fourth configuration , in the apparatus of the third configuration , an accumulation determination unit that determines whether or not an integrated value of the amount of change accumulated by the second correction unit exceeds an allowable upper limit; A predetermined command that is neither the first command value nor the second command value among the command values for the actuators in the system when the cumulative determination means determines that the integrated value of the change amount exceeds the allowable upper limit. It is effective to include a means for performing either one of main ignition timing control by value correction and predetermined fail-safe processing. With such a configuration, it is possible to more suitably prevent or suppress inconvenience caused by the control deviation of the second correction unit. When the main ignition timing can be controlled to an appropriate value with a command value other than the first and second command values, the main ignition timing control is executed and cannot be controlled (there is no such command value). ), A predetermined fail-safe process is executed, so that it is possible to notify that fact or take some measures. The failsafe process includes, for example, a process for storing a diagnosis code in a nonvolatile memory, a process for lighting a predetermined warning light, a process for sounding a warning sound (including a process for playing a predetermined music or message), and the like. Can be adopted.

By the way, the above-mentioned inconveniences such as rapid heat generation due to the combustion of a large amount of fuel at a time, and noise, etc., as described above, can occur in one combustion cycle of the engine prior to the main injection (see FIG. For example, there is a place caused by unburned fuel of prior sub-injection (for example, so-called pilot injection) that injects a smaller amount of injection than main injection. Therefore, the first to fourth any one of the configuration of, as in the fifth configuration, the pilot pre sub injection execution means (e.g., injection map for performing such a pre-sub-injection (e.g., the pilot injection and pre-injection, etc.) The present invention is particularly effective when applied to a configuration including an injection unit having injection.

In this case, as in the sixth configuration , as the second command value, the injection of the preliminary sub-injection (for example, so-called pilot injection) performed by the preliminary sub-injection execution unit among the command values for the fuel injection valve. It is effective to use a command value relating to an aspect (for example, the number of injection stages, injection timing, injection amount, etc.). With such a configuration, the second correction means can be realized more easily and accurately.

Further, in this case, as in the seventh configuration , the second command value is a command related to the injection amount of single-stage pre-sub-injection performed by the pre-sub-injection execution means among the command values for the fuel injection valve. It is effective to adopt a configuration that is a value.

According to the inventor's experiment and the like, there is a good correlation between the main ignition timing and the injection amount of the preliminary sub-injection, particularly when single-stage injection (for example, the aforementioned pilot injection) is performed as the preliminary sub-injection performed before the main injection. (See FIG. 4). For this reason, in order to realize the second correction means more easily and accurately, it is effective to use the seventh configuration as the sixth configuration .

Further, as in the eighth configuration, when the main injection execution timing is corrected to the advance side or the retard side by the first correction unit, the preliminary sub-injection is performed in the same direction as the advance / retard direction. Change the execution time. In this case, for example, it is desirable to change the execution timing of the preliminary sub-injection to the advance side or the retard side by the same amount as the change amount on the advance side or the retard side of the main injection execution timing.

According to the eighth configuration , the interval between the preliminary sub-injection and the main injection (injection interval) can be maintained at a desired interval, and when pressure fluctuation occurs inside the fuel injection valve with the execution of the preliminary sub-injection. The fluctuation of the main injection amount due to the pressure fluctuation can be suppressed. As a result, when both the preliminary sub-injection and the main injection are executed, the main injection amount can be properly controlled and stable even if the execution timing of the main injection is changed to control the ignition timing of the main injection. The fuel injection control can be realized.

As the second command value, parameters other than the preliminary sub-injection can be used. In a ninth configuration , in the apparatus having any one of the first to fifth configurations , the second command value is a parameter that affects the ease of fuel ignition (combustion rate) in the combustion chamber. It is characterized by.

  These parameters include, for example, the in-cylinder pressure at ignition (the higher the pressure, the easier it is to ignite), the in-cylinder temperature at ignition (the higher the temperature, the easier it is to ignite), and the gas composition of the gas mixture at ignition (The easier it is to ignite, the easier it is to ignite), the degree of mixture of the air-fuel mixture at the time of ignition (the easier it is to ignite, the easier it is to ignite), and the ignition assist device (eg, glow plug) ), The parameters that affect at least one of the spray amount of the injection valve, and the like.

10 in the structure of the apparatus of any one of the configurations described above first to ninth, the first permissible range used by the determining means, the allowable deviation from the first reference value of a predetermined first reference value that Whether or not a deviation amount between the first command value corrected by the first correction means and the first reference value is smaller than the allowable deviation amount. (E.g., judging by comparing with a predetermined threshold value) and determining that the first command value is within the first allowable range when the deviation amount is smaller than the allowable deviation amount. To do.

  In general, the main injection execution timing has a target value (predetermined reference value). The closer the main injection execution timing is to the target value, that is, the smaller the deviation (deviation amount) from the target value, the better the combustion characteristics. It is done. Therefore, such a configuration is effective for setting the first allowable range easily and appropriately.

In this case, as in the eleventh configuration , the first reference value used in the determination means is the initial value of the injection control map in which the command value for the fuel injection valve is associated with the predetermined parameter for the engine. It is effective to adopt a configuration that is a value. In general in-vehicle engine control, an injection control map (a so-called adaptation map generally stored in a ROM) is used. For this reason, as a configuration for setting the first allowable range, the use of such a map is highly practical.

Above for the first 1 to 11 wherein the ignition timing detection means in the apparatus of any one of the configuration of, as in the twelfth configuration, the detection signal corresponding to the pressure (cylinder pressure) of the combustion chamber with respect to said cylinder Is applied to a configuration in which an in-cylinder pressure sensor is provided, and as the ignition timing detection means, one that detects a main ignition timing or a parameter correlated with this timing based on the output of the in-cylinder pressure sensor is used. It is valid. With such a configuration, the main ignition timing or a parameter correlated with this timing can be detected with high accuracy while having a highly practical configuration.

Further, in order to increase the practicality and detection accuracy of the device of the twelfth configuration, the ignition timing detection means is operated for a predetermined time (for example, a unit) based on the output of the in-cylinder pressure sensor as in the thirteenth configuration. Obtain the data transition (so-called waveform) of the heat generation rate, which is the amount of heat generated per unit time (such as time and unit output shaft rotation speed), and detect the main ignition timing or parameters correlated with this timing based on the obtained data transition It is effective to adopt a configuration that is a thing.

The inventor has invented the devices of the fourteenth to eighteenth configurations as a device (combustion control device) having a function equivalent to each of the above devices. Hereinafter, each of these devices will be described.

First, in the fourteenth configuration , a fuel is ignited and burned based on compression in a combustion chamber in a cylinder, and power is generated in the output shaft by the combustion, and the fuel is directly supplied to the combustion chamber. A main injection for mainly generating power in the output shaft in an apparatus for controlling an operation of at least one actuator in the system, which is applied to an engine system including an in-cylinder fuel injection valve for injection. Ignition timing detection means for detecting a main ignition timing that is the ignition timing of the main fuel injected by the engine, or a parameter correlated with this timing, permission condition determination means for determining whether or not a predetermined permission condition is satisfied, and the permission condition determination Only when it is determined by the means that the permission condition is satisfied, in the direction of the detection value by the ignition timing detection means within the predetermined range, Serial characterized by comprising: a first correction means for correcting the first command value is a command value of the main injection execution timing, the relative fuel injection valve.

Further, in the fifteenth configuration , the fuel is ignited and burned based on the compression in the combustion chamber in the cylinder, and power is generated in the output shaft by the combustion, and the fuel is directly supplied to the combustion chamber. A device for controlling the operation of at least one actuator in the system, which is applied to an engine system including a fuel injection valve for in-cylinder injection that supplies fuel to a main body for mainly generating power in the output shaft Main ignition timing, which is the ignition timing of the main fuel injected by injection, or ignition timing detection means for detecting a parameter correlated with this timing, and a direction in which the detection value by the ignition timing detection means falls within a predetermined range The first correction means for correcting the first command value, which is the command value of the main injection execution timing for the fuel injection valve, and the success or failure of a predetermined permission condition are determined. When the permission condition determining unit and the permission condition determining unit determine that the permission condition is not satisfied, a predetermined condition (for example, the permission condition) is satisfied when the correction coefficient is updated by the first correcting unit. And a means for prohibiting or limiting up to.

  With these devices, when the permission condition is not satisfied, the correction (update of the correction coefficient) of the first command value (the command value of the main injection execution timing for the fuel injection valve) is prohibited or restricted. For this reason, the deterioration (noise etc.) of the combustion characteristic resulting from excessive correction | amendment comes to be prevented or suppressed more reliably.

More specifically, as in the sixteenth configuration , in the apparatus configured as described above in the fourteenth or fifteenth configuration , the permission condition determination unit determines that the first command value corrected by the first correction unit is within a predetermined range. And determining whether the permission condition is satisfied when the first command value is within the first allowable range. It is possible to suitably prevent or suppress the deterioration of combustion characteristics (noise, etc.) due to the ignition timing shift.

In the seventeenth configuration , the fuel is ignited and burned based on the compression in the combustion chamber in the cylinder, and the fuel is directly supplied to the combustion chamber. And a fuel injection valve for in-cylinder injection to be supplied to the engine. The main system for mainly generating power in the output shaft by controlling the operation of at least one actuator in the system. In a device for controlling a main ignition timing which is an ignition timing of main fuel injected by injection, a main ignition timing is set by variably setting a first command value which is a command value of a main injection execution timing for the fuel injection valve. In addition to the first control value and the first command value, among command values for actuators in the system, other than the first command value By variably setting the second command value, which is a predetermined command value, each control law with the second control for bringing the main ignition timing closer to the target value is prepared in a manner that can be executed in advance (for example, as a program in the storage device) If the difference between the main ignition timing at that time and a target value is sufficiently small, the first control is performed to perform main ignition. Control means for bringing the timing closer to the target value, and when the difference between the main ignition timing at that time and the target value is not sufficiently small, the second control is performed to bring the main ignition timing closer to the target value. And

  With such a configuration, it is possible to suppress or suppress the deterioration of combustion characteristics (noise or the like) due to excessive control deviation by suppressing the deviation of the first command value to a small value.

In this case, as in the eighteenth configuration , when the difference between the main ignition timing at that time and the target value is not sufficiently small, the control amount of the first command value is set (for example, within a predetermined range). (2) By performing the second control in a restricted state and setting the main ignition timing close to the target value, it is possible to more reliably prevent or suppress deterioration of combustion characteristics (noise, etc.). become able to.

As described above, if the time (main ignition delay time) from the execution (start) of main injection to the start of combustion (ignition) becomes too long, a large amount of fuel is burnt at once. Inconveniences such as heat generation and eventually noise occur. On the other hand, in the cylinder injection engine, since the fuel is directly injected into the cylinder, if the main ignition delay time becomes too short, the mixing time of the intake air and fuel in the combustion chamber (premixing time) Insufficient time cannot be secured and desired combustion characteristics cannot be obtained. The devices of the nineteenth to twenty- fifth configurations are devices invented to avoid such inconvenience by paying attention to the main ignition delay time.

First, in the nineteenth aspect of the invention, a fuel is ignited and combusted based on compression in a combustion chamber in a cylinder, and power is generated in the output shaft by the combustion, and the fuel is directly supplied to the combustion chamber. In an apparatus for controlling the operation of at least one actuator in the system, which is applied to an engine system including an in-cylinder fuel injection valve for injecting and supplying the engine in order to mainly generate power for the output shaft An ignition delay time detection means for detecting a main ignition delay time which is a time from when main fuel is injected by main injection until the main fuel is ignited (combustion is started), or a parameter related to this time; Based on the detected value by the ignition delay time detection means, it affects the main ignition delay time among the command values for the actuators in the system. Characterized in that it and a ignition delay time control means for variably setting the ignition delay command value is (which may be a plurality of kinds of command values in one command value) predetermined command value.

  With such a configuration, the main ignition delay time is controlled to an appropriate value by the ignition delay time control means, and the inconvenience due to the excessive ignition delay time deviation can be suitably prevented or suppressed.

The ignition delay command value is, for example, a parameter that affects the ease of combustion of the fuel in the combustion chamber (combustion rate), such as the in-cylinder pressure during ignition (the greater the pressure, the greater the ease of ignition). In-cylinder temperature at ignition (the higher the temperature, the easier it is to ignite), the gas component of the air-fuel mixture at ignition (the more combustible gas, the easier it is to ignite), the degree of mixture of the air-fuel mixture at ignition (The closer the mixing degree is to a sufficient value, the easier it is to ignite), the driving amount of the ignition assisting device (for example, a glow plug) (the larger the driving amount, the easier it is to ignite), and the spray of the fuel injection valve Parameters that affect at least one of the forms can be used. However, in order to more easily and accurately realize the ignition delay time control means, as in the twentieth configuration , in the apparatus of the nineteenth configuration , the ignition delay command value is equal to the command value for the fuel injection valve. Of these, prior sub-injection (for example, so-called pilot injection) injection mode (for example, so-called pilot injection) that injects fuel (for example, an injection amount smaller than main injection) prior to execution of the main injection in one combustion cycle of the engine (for example, It is effective to adopt a configuration that is a command value relating to the number of injection stages, injection timing, injection amount, and the like.

Further, in this case, as in the twenty-first configuration , the command value related to the injection mode of the preliminary sub-injection is a command value related to the injection amount of the single-stage preliminary sub-injection among the command values for the fuel injection valve. Is effective.

According to the inventor's experiment and the like, the main ignition delay time and the injection amount of the preliminary sub-injection are particularly good when single-stage injection (for example, the aforementioned pilot injection) is performed as the preliminary sub-injection performed before the main injection. Correlate (see FIG. 4). Therefore, the in realizing ignition delay time control means easily and appropriately has a device structure of the first 20, it is effective to adopt a configuration of the first 21.

In a twenty- second configuration , in the apparatus according to any one of the nineteenth to twenty- first configurations , the ignition delay time detecting means is a main injection start timing that is a timing at which main injection is started by the fuel injection valve, or this An injection timing detection unit that detects a parameter that correlates to the timing (for example, a timing at a predetermined point in the waveform of the heat generation rate, which is the amount of heat generated per predetermined time), and a main injection for mainly generating power in the output shaft The main ignition timing, which is the ignition timing of the main fuel injected by the engine, or an ignition timing detection unit that detects a parameter related to this timing, and based on the detection values by these injection timing detection unit and ignition timing detection unit, An ignition delay time calculating unit that calculates an ignition delay time or a parameter correlated with this time.

  With such a configuration, the ignition delay time detecting means can be realized more easily and accurately.

In particular, as this first 22 the injection timing detecting section in the apparatus of the configuration of, as in the configuration of the 23, the command value for the fuel injection valve, and a parameter (e.g. injection valve indicating the operating state of the fuel injection valve It is effective to employ one that detects the main injection start timing or a parameter that correlates with this timing based on at least one of the needle lift amount and the rail pressure in the common rail system.

On the other hand, as the ignition timing detection unit in the twenty-second configuration , a configuration similar to the ignition timing detection means ( first to eighteenth configurations ) can be adopted. That is, for example, it is effective to detect the main ignition timing or a parameter correlated with this timing based on the output of the in-cylinder pressure sensor.

As the ignition delay time control means in the device of any one of these 19th to 23rd configurations , for example, as in the 24th configuration ,
Means for variably setting the ignition delay command value so that the detection value by the ignition delay time detection means approaches a predetermined reference value;
Or like the 25th configuration ,
When it is determined whether or not the detected value by the ignition delay time detecting means is within a predetermined allowable range (for example, set as a distance from the reference value), and the detected value is not within the allowable range Means for correcting the ignition delay command value in a direction in which the detected value falls within an allowable range.
It is effective to adopt such means. With these configurations, even if the main ignition delay time (strictly, the detected value) falls outside the allowable range, the main ignition delay time is controlled to a predetermined reference value or allowable range by the ignition delay time control means. Thus, it is possible to suitably prevent or suppress inconvenience due to the above-described ignition delay time shift. In this case as well, as in the devices having the second to fourth configurations , the main ignition delay time is automatically converged within the reference value and the allowable range by repeatedly performing such processing.

In the twenty-sixth configuration , the present invention is applied to an engine system including a fuel injection valve that directly injects fuel into a combustion chamber of a compression ignition engine, and a plurality of fuel injections by the fuel injection valve during one combustion cycle of the engine. A compression ignition type cylinder that executes (so-called multi-stage injection) and executes ignition timing feedback control so as to converge the ignition timing of the fuel with respect to a specific injection that is the second or subsequent fuel injection among the plurality of fuel injections In the internal combustion engine combustion control device, the ignition timing deviation between the actual ignition timing and its target for the specific injection, or at least one of the ignition timing feedback control amounts calculated based on the deviation is equal to or greater than a predetermined value. A determination means for determining, and either the ignition timing deviation or the ignition timing feedback control amount is determined by the determination means; When it is determined that it is value or more, characterized in that it comprises, before the injection control means for changing the injection amount for the previous injection immediately before the specific injection.

  According to the above configuration, when at least one of the ignition timing deviation of the specific injection (for example, main injection) or the ignition timing feedback control amount is equal to or greater than the predetermined value, the injection is performed for the previous injection (for example, pilot injection) immediately before the specific injection. By changing the amount, the ignition timing deviation of the specific injection or the ignition timing feedback control amount becomes small. As a result, the combustion characteristics of the internal combustion engine, particularly the combustion characteristics related to the ignition timing of the supplied fuel by the specific injection (main injection) can be improved.

In the twenty-seventh configuration , when the ignition timing deviation or ignition timing feedback control amount of the specific injection (for example, main injection) is equivalent to that the actual ignition timing is later than the target, the injection amount of the previous injection is increased. However, when the actual ignition timing is equivalent to being earlier than the target, the injection amount of the previous injection is reduced. In short, according to the inventors of the present application, by increasing the injection amount of the previous injection, the fuel ignition timing of the specific injection immediately after that is advanced, and conversely, by reducing the injection amount of the previous injection, the specific injection immediately after that It has been confirmed that the fuel ignition timing is delayed. Therefore, according to the twenty-seventh configuration , a configuration suitable for reducing the ignition timing deviation or ignition timing feedback control amount of the specific injection can be realized.

Here, as in the twenty-eighth configuration , the predetermined value for comparing and determining the ignition timing deviation of specific injection (for example, main injection) or the ignition timing feedback control variable is variable based on the target ignition timing of the specific injection. It is good to set to. Thereby, even if the target ignition timing of the specific injection is changed in accordance with the engine operating state or the like every time, an appropriate combustion characteristic can be realized each time.

As in the 29th configuration, when the execution timing of the specific injection is changed to the advance side or the retard side in the ignition timing feedback control of the specific injection, the previous injection is performed in the same direction as the advance / retard direction. Change the execution time. In this case, for example, it is desirable to change the execution timing of the previous injection to the advance side or the retard side by the same amount as the change amount of the advance side or the retard side of the specific injection execution time.

According to the twenty-ninth configuration , the interval between the pre-injection and the specific injection (injection interval) can be maintained at a desired interval, and when the pressure fluctuation occurs inside the fuel injection valve with the execution of the pre-injection, the pressure The fluctuation of the fuel injection amount of the specific injection due to the fluctuation can be suppressed. As a result, even when the pre-injection and the specific injection are executed together, the fuel injection amount of the specific injection can be properly controlled even if the execution timing of the specific injection is changed to control the ignition timing of the specific injection. Stable fuel injection control can be realized.

By the way, depending on the type of business, application, etc., when this device is used for engine control instead of the unit of the combustion control device, for example, in the engine control, not only the combustion control device but also other related devices (for example, sensors In some cases, it is handled as an engine control system constructed including various devices related to control of actuators and the like. The apparatus of any one of the configurations of the first 1 to 29 also, as one of the applications, it is envisioned to be used incorporated in the engine control system. Configuration of the 30, which corresponds to such applications, namely as an engine control system, a combustion control apparatus of the first 1 to 29 any one of the configurations HCCI injection engine of, combustion control device Actuators in the engine system to be controlled, and engine control means (for example, engine output shaft torque control or rotational speed control) for performing predetermined control related to the engine based on the operation of the actuators. It is characterized by providing. The apparatus of any one of the configurations of the first 1-29 is particularly beneficial with integrated into the engine control system.

(First embodiment)
Hereinafter, a first embodiment in which a combustion control device and an engine control system of a compression ignition type cylinder injection engine according to the present invention are embodied will be described with reference to FIGS. The engine control system of the present embodiment is a common rail fuel injection control system (high pressure fuel supply system) that controls a compression ignition type diesel engine (internal combustion engine) as a power source for automobiles. In this system as well, as in the system described in Patent Document 1 described above, high-pressure fuel (for example, light oil having an injection pressure of “1000 atm” or more) is directly supplied to the combustion chamber in the engine cylinder (portion where fuel combustion is performed) ( Direct injection).

  First, the schematic configuration of the engine control system according to the present embodiment will be described with reference to FIG. The signal lines in FIG. 1 correspond to a wiring layout. As an engine to be controlled by this system (engine 10 in the figure), a multi-cylinder (for example, in-line 4-cylinder) engine for a four-wheel automobile is assumed. However, in FIG. 1, only one cylinder (cylinder 12 in the figure) is shown for convenience of explanation. The engine 10 is a 4-stroke reciprocating in-cylinder injection engine (internal combustion engine). That is, in this engine 10, a cylinder discrimination sensor (electromagnetic pickup) provided on the camshafts (not shown) of the intake / exhaust valves 21 and 22 sequentially discriminates the target cylinder at that time. For each of the four cylinders # 1 to # 4, one combustion cycle by four strokes of intake, compression, combustion, and exhaust is a “720 ° CA” period, specifically, for example, “180 ° CA” is shifted between the cylinders. The cylinders # 1, # 3, # 4, and # 2 are sequentially executed. Since the configuration of these four cylinders # 1 to # 4 is basically the same, here, the system will be described with a focus on one cylinder (cylinder) 12.

  As shown in FIG. 1, this engine control system uses a diesel engine 10 equipped with a common rail fuel injection device as a control target, and various sensors and ECU (electronic control unit) 80 for controlling the engine 10. Etc. are built.

  The engine 10 to be controlled here basically includes a piston 13 housed in a cylinder 12 formed in a cylinder block 11, and an output shaft (not shown) is reciprocated by the piston 13. As the crankshaft rotates.

  The cylinder block 11 is provided with a cooling water passage (water jacket) 14 for circulating the cooling water through the engine 10 and a cooling water temperature sensor 14 a for detecting the temperature (cooling water temperature) of the cooling water in the water passage 14. The engine 10 is cooled by the cooling water. A cylinder head 15 is fixed to the upper end surface of the cylinder block 11, and a combustion chamber 16 is formed between the cylinder head 15 and the crown surface of the piston 13.

  In the cylinder head 15, for example, two intake ports 17 (intake ports) and exhaust ports 18 (exhaust ports) that open to the combustion chamber 16 are formed, for example, two for each cylinder (a total of four ports). The intake port 17 and the exhaust port 18 are respectively driven by an intake valve (intake valve) 21 and an exhaust valve (exhaust valve) that are driven by a cam (not shown) (specifically, a cam attached to a camshaft interlocked with the crankshaft). 22 is opened and closed. Further, in order to enable communication between the combustion chamber 16 in the cylinder 12 and the outside of the vehicle (outside air) through each of these ports, an intake pipe (intake air) for sucking outside air (fresh air) into each cylinder is provided in the intake port 17. A manifold) 23 is connected, and an exhaust pipe (exhaust manifold) 24 for discharging combustion gas (exhaust gas) from each cylinder is connected to the exhaust port 18.

  The intake pipe 23 constituting the intake system of the engine 10 includes an air cleaner 31 at the most upstream portion of the intake pipe 23 and an air amount (new air amount) sucked in while removing foreign substances in the air through the air cleaner 31. An air flow meter 32 (for example, a hot wire type air flow meter) that detects and outputs an electrical signal downstream from 31 is provided. An intercooler 33 for cooling the intake air is provided on the downstream side of the air flow meter 32. Further, on the downstream side of the intercooler 33, an electronically controlled throttle valve 34 whose opening degree is electronically adjusted by an actuator such as a DC motor, and the opening degree and movement (opening degree fluctuation) of the throttle valve 34 are detected. A throttle opening sensor 34a is provided. Further, in the vicinity of the intake port 17 further downstream, an intake pressure sensor 35 that detects intake pressure and outputs it as an electrical signal, and an intake air temperature sensor 36 that detects intake temperature and outputs it as an electrical signal are provided. .

  On the other hand, in the exhaust pipe 24 that constitutes the exhaust system of the engine 10, an exhaust pressure sensor 24a that detects the exhaust pressure and outputs it as an electrical signal in the vicinity of the exhaust port 18, and detects the exhaust temperature and outputs it as an electrical signal. An exhaust temperature sensor 24b is provided. Further, on the downstream side, a DPF (Diesel Particulate Filter) 38 for collecting PM in the exhaust and NOx for purifying NOx in the exhaust are provided as an exhaust aftertreatment system for purifying the exhaust. An occlusion reduction type catalyst 39 (hereinafter referred to as NOx catalyst 39) is provided. In the present embodiment, the DPF 38 is provided on the exhaust upstream side of the NOx catalyst 39.

  Among these, the DPF 38 is a continuous regeneration type PM removal filter that collects PM (Particulate Matter, particulate matter) in the exhaust, and repeatedly burns and removes the collected PM by post injection or the like (corresponding to regeneration processing). ) Can be used continuously. The DPF 38 carries a platinum-based oxidation catalyst (not shown) and can remove HC and CO together with a soluble organic component (SOF) which is one of the PM components.

  On the other hand, the NOx catalyst 39 is made of, for example, an alkaline earth material (occlusion material) and platinum. When the exhaust atmosphere has an air-fuel ratio lean (an air-fuel ratio having a fuel ratio lower than the stoichiometric air-fuel ratio), NOx in the exhaust is removed. When the air-fuel ratio is occluded and the air-fuel ratio becomes rich (the air-fuel ratio higher in fuel ratio than the stoichiometric air-fuel ratio), it has the characteristic of reducing and removing the stored NOx by reducing components such as HC and CO in the exhaust. By repeating NOx occlusion / reduction (release) by the NOx catalyst 39, it becomes possible to purify NOx in the exhaust gas and reduce the NOx emission amount.

  An exhaust temperature sensor 38a for detecting the exhaust temperature and an A / F sensor 38b for detecting the oxygen concentration in the exhaust are provided upstream of the DPF 38 in the exhaust pipe 24. On the other hand, A / F sensors 39a and 39b are also provided on the upstream side and the downstream side of the NOx catalyst 39, respectively. Here, these A / F sensors 38b, 39a, and 39b are all oxygen concentration sensors that output an oxygen concentration detection signal corresponding to the oxygen concentration in the exhaust gas from time to time. Calculations are performed sequentially. The oxygen concentration detection signals as sensor outputs of these A / F sensors 38b, 39a, 39b are adjusted so as to change linearly in accordance with the oxygen concentration. The exhaust temperature sensor 38a and the A / F sensors 38b, 39a, 39b play a particularly important role in the regeneration process of the DPF 38 and the NOx catalyst 39, mainly for detecting the start / end timing of the regeneration process. Used.

  Further, in this system, a turbocharger 50 is disposed between the intake pipe 23 and the exhaust pipe 24. The turbocharger 50 is provided in the middle of the intake pipe 23 (between the air flow meter 32 and the intercooler 33) and in the middle of the exhaust pipe 24 (upstream of the exhaust temperature sensor 38a). The compressor 51 and the turbine 52 are connected by a shaft 53. That is, the exhaust turbine 52 is rotated by the exhaust gas flowing through the exhaust pipe 24, and the rotational force is transmitted to the intake compressor 51 via the shaft 53, and the air flowing through the intake pipe 23 is compressed by the intake compressor 51 and excessively discharged. Pay is done. This supercharging increases the charging efficiency of the intake air to each cylinder, and at that time, the supercharged air is cooled by the intercooler 33, thereby further increasing the charging efficiency to each cylinder. become.

  Furthermore, an EGR device 60 that recirculates (recirculates) part of the exhaust gas as an exhaust gas recirculation (EGR) gas to the intake system is also disposed between the intake pipe 23 and the exhaust pipe 24. The EGR device 60 is roughly composed of an EGR pipe 61 provided so as to communicate the intake pipe 23 and the exhaust pipe 24 in the vicinity of the intake / exhaust port, an electromagnetic valve provided on the downstream side of the throttle valve 34, and the like. And an EGR valve 62. The passage area of the EGR pipe 61 and thus the EGR rate (the ratio of the EGR gas returned to the cylinder with respect to the entire exhaust gas) can be adjusted by the valve opening of the EGR valve 62. For example, in a state where the EGR valve 62 is fully closed, the EGR pipe 61 is shut off and the EGR amount becomes “0”. More specifically, here, the EGR pipe 61 (the connection path of the intake and exhaust passages) branches into two (branch passages 61a and 61b) at a predetermined portion on the exhaust side and joins again on the exhaust downstream side (intake side). The EGR valve 62 is connected to the intake passage. Among these, the branch passage 61a is provided with a water-cooled EGR cooler 63 (cooling device) that cools EGR gas passing through the passage 61a with cooling water. As a result, in the two branch passages 61a and 61b, the heat radiation amounts due to the gas flow from the branch portion (exhaust side) to the merge portion (intake side) are different from each other. In addition, a bypass valve 61c is provided at the joining portion of the two branch passages 61a and 61b so that the flow area (closing degree) of one of the branch passages 61a and 61b is variable and the other is opened. In the EGR device 60, the exhaust gas recirculation path is determined by the state of the bypass valve 61c. That is, for example, assuming that the exhaust temperature is “500 ° C.”, when the branch passage 61a is selected as the recirculation path, the EGR cooler 63 cools the EGR gas to about “100 ° C.”. On the other hand, when the branch passage 61b is selected, the EGR gas is not cooled by the EGR cooler 63 and reaches about “300 ° C.”. In this EGR device 60, based on such a configuration, a part of the exhaust gas is recirculated to the intake system through the EGR pipe 61, so that the combustion temperature can be lowered and the generation of NOx can be reduced. Further, the intake air temperature can be adjusted (variable control) through selection (switching) of the recirculation path by the bypass valve 61c and variable control of the flow area.

  On the other hand, an electromagnetically driven injector (fuel) that supplies fuel (light oil) for combustion in the combustion chamber 16 directly into the cylinder 12 (in-cylinder) in the combustion chamber 16 in the cylinder 12. The pressure in the cylinder 12 (in-cylinder pressure) was measured by an injection valve 27 and a detection part (tip end of the probe inserted into the combustion chamber 16) located in the combustion chamber 16 and corresponded to the measured value. An in-cylinder pressure sensor 28 that outputs a detection signal (electric signal) is further provided. Here, for the sake of convenience, only the injector 27 and the in-cylinder pressure sensor 28 provided in one cylinder (cylinder 12) are illustrated, but such an injector and sensor are provided for each cylinder of the engine 10. Yes. Each injector of the engine 10 including the injector 27 is connected to a fuel tank 44 via a fuel pipe 41, a common rail 42, and a fuel pump 43. That is, the fuel in the fuel tank 44 pumped up by the fuel pump 43 through a filter (not shown) is pressurized to a predetermined fuel pressure (for example, “1000 atmospheres” or more) in the common rail 42 as a pressure accumulation pipe, It is distributed (supplied) to each injector through the fuel pipe 41. Further, the common rail 42 is provided with a fuel pressure sensor 42a for detecting the fuel pressure in the common rail 42 (common rail pressure), and the fuel injection pressure of each injector of the engine 10 can be managed.

  FIG. 2 shows the detailed structure of the injector 27. The injector 27 according to the present embodiment is a hydraulically driven fuel injection valve that uses engine fuel for combustion (fuel in the fuel tank 44). ) Is done through.

  As shown in FIG. 2, the injector 27 is an inner open type fuel injection valve, and is configured as a so-called normally closed type fuel injection valve that is closed when not energized. That is, in this injector 27, the degree of sealing of the hydraulic chamber Cd and the pressure in the hydraulic chamber Cd (the back pressure of the needle 27b) are changed according to the energized state (energized / non-energized) of the solenoid 27a constituting the two-way solenoid valve. The needle 27b reciprocates (up and down) in the valve cylinder (inside the housing 27d) according to or against the extension force of the spring 27c (coil spring). As a result, the fuel supply passage up to the injection holes 27e (perforated as many as necessary) is opened and closed halfway (specifically, a tapered seat surface on which the needle 27b is seated or separated based on the reciprocating motion). At this time, the drive control of the needle 27b is performed through so-called PWM (Pulse Width Modulation) control. That is, a pulse signal (energization signal) is sent from the ECU 80 to the drive unit (the two-way electromagnetic valve) of the needle 27b. The lift amount (the degree of separation from the seat surface) of the needle 27b is variably controlled based on the pulse width (corresponding to the energization time). In this control, the lift amount increases as the energization time increases. As the amount increases, the injection rate (the amount of fuel injected per unit time) increases. Incidentally, the pressure increasing process of the hydraulic chamber Cd is performed by supplying fuel from the common rail 42. On the other hand, the decompression process of the hydraulic chamber Cd is performed by returning the fuel in the hydraulic chamber Cd to the fuel tank 44 through a pipe (not shown) connecting the injector 27 and the fuel tank 44.

  As described above, the injector 27 opens and closes the injector 27 by opening and closing (opening / closing) the fuel supply passage to the injection hole 27e based on a predetermined reciprocating motion inside the valve body (housing 27d). A needle 27b for closing the valve is provided. In the non-driving state, the needle 27b is displaced toward the valve closing side by a force constantly applied to the valve closing side (extension force by the spring 27c), and in the driving state, a driving force is applied. The needle 27b is displaced toward the valve opening side against the extension force of the spring 27c. At this time, the lift amount of the needle 27b changes approximately symmetrically between the non-driven state and the driven state.

  In the engine 10, a required amount of fuel is injected and supplied to each cylinder at any time by the valve opening drive of these injectors 27. That is, when the engine 10 is operated, intake air is introduced into the combustion chamber 16 of the cylinder 12 from the intake pipe 23 by the opening operation of the intake valve 21, and this is mixed with the fuel injected and supplied from the injector 27. Compressed by the piston 13 in the cylinder 12 and ignited (self-ignited) and combusted, and the exhaust valve 22 is opened to discharge the combusted exhaust gas to the exhaust pipe 24.

  In addition to the above sensors, the vehicle (not shown) is further provided with various sensors for vehicle control. For example, a crank angle sensor 71 (for example, an electromagnetic pickup) that outputs a crank angle signal at every predetermined crank angle (for example, at a cycle of 30 ° CA) is provided on the outer peripheral side of the crank shaft that is the output shaft of the engine 10. Are provided for detecting the rotational angle position, rotational speed (engine rotational speed), and the like. In addition, an accelerator sensor 72 that outputs an electric signal corresponding to the state (displacement amount) of the pedal to the accelerator pedal (driving operation unit) detects an operation amount (depression amount) of the accelerator pedal by the driver. Is provided.

  In such a system, the ECU 80 is a part that functions as a combustion control device of the present embodiment and performs engine control mainly as an electronic control unit. The ECU 80 (engine control ECU) includes a well-known microcomputer (not shown), grasps the operating state of the engine 10 and user requests based on the detection signals of the various sensors, and according to the above, By operating various actuators such as the throttle valve 34 and the injector 27, various controls related to the engine 10 are performed in an optimum manner according to the situation at that time.

  The microcomputer mounted on the ECU 80 basically includes a CPU (basic processing unit) for performing various calculations, and a RAM (main memory for temporarily storing data and calculation results during the calculation). Random Access Memory (ROM), ROM as a program memory (read-only storage device), EEPROM (electrically rewritable non-volatile memory) as data storage memory, and backup RAM (on-vehicle battery etc. even after main power supply of ECU is stopped) Memory that is constantly powered by a backup power supply), signal processing devices such as A / D converters and clock generation circuits, various arithmetic devices such as input / output ports for inputting / outputting signals to / from the outside, A storage device, a signal processing device, a communication device, a power supply circuit, and the like are included. Furthermore, in the present embodiment, by providing a high-speed digital processing processor (DSP) separately from the CPU, the processing speed of signal processing (especially signal processing related to the output of the in-cylinder pressure sensor 28) performed on control is improved. I am doing so. The ROM stores various programs (control laws) related to engine control including a program related to the ignition timing control, a control map, and the like, and a data storage memory (for example, EEPROM) stores design data of the engine 10. Various control data including the above are stored in advance.

  In the present embodiment, the ECU 80 satisfies the torque (required torque) to be generated on the output shaft (crankshaft) at that time, based on various sensor outputs (detection signals) input as needed, and thus satisfies the required torque. The fuel injection amount is calculated. In this way, by variably setting the fuel injection amount of the injector 27, the indicated torque (generated torque) generated through fuel combustion in the cylinder (combustion chamber), and thus actually output to the output shaft (crankshaft). The shaft torque (output torque) is controlled (matched to the required torque). That is, the ECU 80 calculates a fuel injection amount corresponding to, for example, the engine operating state from time to time and the amount of operation of the accelerator pedal by the driver, and injects fuel at that fuel injection amount in synchronization with a desired injection timing. An instructing injection control signal (drive amount) is output to the injector 27. Thus, that is, based on the drive amount (for example, valve opening time) of the injector 27, the output torque of the engine 10 is controlled to the target value. In the present embodiment, a portion for performing such torque control (specifically, a program in the ECU 80) corresponds to “engine control means”.

  As is well known, in a diesel engine, the intake throttle valve (throttle valve 34) provided in the intake passage of the engine 10 is substantially fully open for the purpose of increasing the amount of fresh air and reducing pumping loss during steady operation. Retained. Therefore, control of the fuel injection amount is mainly used as combustion control during steady operation (particularly combustion control related to torque adjustment). Hereinafter, the basic procedure of the fuel injection control according to the present embodiment will be described with reference to FIG. Note that the values of various parameters used in the processing of FIG. 3 are stored as needed in a storage device such as a RAM, EEPROM, or backup RAM mounted on the ECU 80, and updated as necessary. The series of processes shown in these drawings is basically executed in order at a frequency of once per combustion cycle for each cylinder of the engine 10 by executing a program stored in the ROM by the ECU 80. The That is, with this program, fuel is supplied to all the cylinders except the idle cylinder in one combustion cycle.

  As shown in FIG. 3, in this series of processes, first, in step S11, predetermined parameters, for example, the engine speed at that time (actually measured value by the crank angle sensor 71) and rail pressure (actually measured value by the fuel pressure sensor 42a) are used. Furthermore, the accelerator operation amount (actual value measured by the accelerator sensor 72) at that time by the driver is read. In the subsequent step S12, an injection pattern is set based on the various parameters read in step S11 (calculating the required torque including the loss due to the external load as necessary). For example, in the case of single-stage injection, the injection amount (injection time) of the injection, and in the case of multi-stage injection pattern, the total injection amount (total injection time) of each injection that contributes to torque is the output shaft. It is variably set according to the torque to be generated on the (crankshaft) (required torque, corresponding to the engine load at that time). Based on the injection pattern, a command value (command signal) for the injector 27 is set. As a result, the pilot injection, pre-injection, after-injection, post-injection and the like described above are appropriately performed together with the main injection in accordance with the vehicle conditions and the like.

  The injection pattern is acquired based on, for example, a predetermined basic injection map (an injection control map or a mathematical expression) stored in the ROM and a correction coefficient. Specifically, for example, an optimum injection pattern (adapted value) is obtained in advance by experiments or the like with respect to an assumed range of the predetermined parameter (step S11) and written in the basic injection map. Incidentally, this injection pattern is determined by parameters such as the number of injection stages (the number of injections in one combustion cycle) and the injection timing (injection timing) and injection time (corresponding to the injection amount) of each injection. Thus, the basic injection map shows the relationship between these parameters and the optimal injection pattern. Then, the injection pattern acquired in this map is corrected based on a correction coefficient (for example, stored in the EEPROM in the ECU 80) that is separately updated (details will be described later) (for example, “set value = value on the map + correction”). By performing the calculation “coefficient”, an injection pattern to be injected at that time, and thus a command signal for the injector 27 corresponding to the injection pattern is obtained. It should be noted that, for the setting of the injection pattern (step S12), each map provided separately for each element of the injection pattern (the number of injection stages, etc.) may be used, or some elements of these injection patterns may be used. You may make it use the map produced collectively (for example, all).

  The injection pattern thus set, and thus the command value (command signal) corresponding to the injection pattern, is used in the subsequent step S13. That is, in step S13, based on the command value (command signal) (specifically, the command signal is output to the injector 27), the drive of the injector 27 is controlled. Then, with the drive control of the injector 27, the series of processes in FIG.

  In the present embodiment, fuel is supplied to the engine 10 through such fuel injection control. Then, prior to execution of main injection for mainly generating output torque in one combustion cycle of engine 10, preliminary sub-injection is executed with a small amount of injection (small amount) than main injection. Like to do. In this way, combustion noise is suppressed and NOx is reduced. Further, the combustion control apparatus of the present embodiment also variably sets (corrects) the command value (first command value) of the main injection execution timing among the command signals to the injector 27, similarly to the device shown in FIG. Thus, a program (first correction means) is provided that moves the detected value of the main ignition timing obtained from the output of the in-cylinder pressure sensor 28 in a direction that falls within a predetermined range. However, in the present embodiment, a program (determination means) for determining whether or not the command value (first command value after correction) corrected by this program is within a predetermined allowable range (first allowable range); When it is determined by this determination that the command value is not within the allowable range, the main ignition timing (strictly, the detected value is determined depending on whether the command value is on the slow side or the early side of the allowable range. ) Is further provided with a program (second correction means) for correcting the injection amount of the pilot injection so as to be moved to the slow side or the fast side in the same direction. Hereinafter, the ignition timing control by the combustion control device of the present embodiment will be described with reference to FIGS. Here, as an example, a case where injection (two-stage injection) of an injection pattern constituted by pilot injection and main injection is performed will be mentioned. In the present embodiment, the portion that performs pilot injection (specifically, the program that performs the processing of FIG. 3 among the programs in the ECU 80) corresponds to “pre-sub-injection execution means”.

  First, the relationship between the injection amount of pilot injection (pre-sub-injection) and the combustion characteristics at the time of main injection (main ignition timing, main injection start timing, etc.) will be described with reference to FIG. In FIG. 4, (a) is a timing chart showing each transition of the injection command to the injector 27, and (b) the state of the injector 27 (lift amount of the needle 27b). Further, (c) to (e) show the heat generation rates (unit time) due to combustion in the cylinder 12 respectively when pilot injection (increase injection, reference injection, and decrease injection) with three different injection amounts is performed. It is a timing chart which shows transition of the amount of heat generation around.

  In the example shown in FIG. 4, when the pulse signal Ps as shown in (a) is given to the injector 27, the lift of the injector 27 as shown by the solid line Lf in (b). The amount (the lift amount of the needle 27b) changes. Incidentally, the time from when energization to the injector 27 is started (rising of the pulse signal Ps) to when the fuel is actually injected corresponds to an invalid injection period (so-called operation delay of the injector 27). Then, as shown in FIGS. 4C to 4E, in accordance with the injection amount of the pilot injection, the ignition timing of the combustion by the subsequent main injection, and thus the combustion starts after the main injection is executed (started). The time until main ignition (ignition) (main ignition delay time) changes. Specifically, as shown by a solid line L1 in FIG. 4D, in the reference injection in which the pilot injection Pt is performed with the reference injection amount (the injection amount that obtains a desired combustion state), the combustion by the main injection Mn Starts at timing t2 (ignites). On the other hand, as shown by the solid line L2 in FIG. 4C, in the increase injection in which the pilot injection Pt is performed with the injection amount larger than the reference (broken line L1), the combustion by the main injection Mn It starts at an earlier timing t1 (ignitions). On the other hand, as shown by a solid line L3 in FIG. 4E, in the reduced injection in which the pilot injection Pt is performed with the injection amount smaller than the reference (broken line L1), the combustion by the main injection Mn is less than that at the reference injection. Also starts at a late timing t3 (ignitions). As described above, it has been confirmed by experiments of the inventor that the ignition timing of combustion by the main injection becomes earlier and the main ignition delay time becomes shorter as the injection amount of the pilot injection becomes larger.

  In addition, as for pilot injection, which is performed with a small region injection amount, the fuel injection amount of the injection and the amount of heat per unit crank angle (unit output shaft rotation angle) generated by combustion of the injected fuel The relationship with (heat generation rate) is as shown in FIG. That is, the heat generation rate increases as the fuel injection amount increases.

  In FIG. 6, the ignition timing control mode of this embodiment is shown as a timing chart. FIG. 6 is a timing chart corresponding to FIG. Here, an example in which ignition timing control is performed when a low cetane number fuel is used will be described in comparison with a comparative example using a high cetane number fuel.

  As shown in FIG. 6, in the present embodiment as well, the detected value (timing t10) of the main ignition timing obtained from the output of the in-cylinder pressure sensor 28 is set within a predetermined range (threshold value) as in the apparatus shown in FIG. The command value (FIG. 6A) relating to the execution timing (injection start timing) of the main injection Mn is corrected so as to be within the range of TH11 to threshold value TH12. However, in this embodiment, the deviation amount between the corrected command value (main injection execution timing) and a predetermined reference value (for example, the value on the basic injection map used in step S12 in FIG. 3) is not sufficiently small (FIG. 6 is not within the allowable range corresponding to the determination value TH13 in FIG. 6, the main ignition timing (depending on whether the command value is on the retard side or the advance side of the allowable range) Strictly speaking, the injection amount of the pilot injection Pt is corrected so that the detected value) is moved to the retard side or the advance side in the same direction. That is, as shown in FIG. 6A, the command value related to the execution timing of the main injection Mn is advanced (for example, corrected from timing t11 to timing t12), and is within an allowable range (a range corresponding to the determination value TH13). In the case where the engine has come to the advance side, the correction of the pilot injection Pt is increased (change from the injection time D11 to the injection time D12), so that the main ignition timing is set to the advance side (the deviation of the command value). The command value related to the execution timing of the main injection Mn is returned to the allowable range. By doing so, it is suitably suppressed that the execution timing (injection start timing) of the main injection described above is advanced too early, and as shown in FIG. 6B, the heat generation rate of the high cetane number fuel The waveform of the heat generation rate (solid line L12 in the figure) according to the waveform (broken line L11 in the figure) can be obtained.

  Next, the process related to the ignition timing control will be described in detail with reference to FIGS. 7 and 8 are flowcharts showing the processing procedure of the same processing. The processing shown in each of these drawings is basically performed by the ECU 80 executing a program stored in the ROM. While the predetermined condition is satisfied (for example, always during engine operation), the processing is sequentially performed at a predetermined processing interval (a cycle equivalent to the processing interval in FIG. 3 or a cycle faster than that). The values of various parameters used in the processes of FIGS. 7 and 8 are also stored as needed in a storage device such as a RAM, EEPROM, or backup RAM mounted on the ECU 80, and updated as necessary.

  As shown in FIG. 7, in this series of processes, first, at step S21, it is determined whether or not the main ignition timing (timing t10 in FIG. 6) has been detected, and the main ignition timing is detected at this step S21. Only when it is determined that the process has been performed, the processes after step S22 are executed. The main ignition timing is calculated separately (in a separate routine) separately from the processing of FIG. FIG. 9 shows a part related to the signal processing of the output of the in-cylinder pressure sensor 28 of the combustion control apparatus (ECU 80) according to the present embodiment as a functional block diagram. An ignition timing calculation process will be described.

This calculation process is largely performed by the heat generation rate calculation unit B1 and the main ignition timing calculation unit B11 in FIG. Here, the heat generation rate calculation unit B1 acquires the engine rotation speed (measured value by the crank angle sensor 71) and the in-cylinder pressure (actual value by the in-cylinder pressure sensor 28) at that time,
dQ / dθ = {κ · P · (dV / dθ) + V (dP / dθ)} / (κ−1) (Equation 1)
Based on the relational expression (Formula 1), the heat generation rate “dQ / dθ” at that time is calculated. In (Expression 1), Q represents the amount of heat generated, θ represents the crank angle, P represents the pressure in the combustion chamber 16 (in-cylinder pressure), and κ represents the specific heat ratio. In the combustion control apparatus of the present embodiment, the heat generation rate calculation unit B1 sequentially calculates the heat generation rate from time to time at a predetermined interval (the shorter the processing load is, the higher the detection accuracy of the heat generation rate waveform is). It has become so.

  On the other hand, the main ignition timing calculation unit B11 in FIG. 9 receives the occasional heat generation rate sequentially calculated by the heat generation rate calculation unit B1, and based on the calculated value of the heat generation rate, the main ignition timing (timing) t10) is calculated (detected). Specifically, for example, the main ignition timing is detected as a timing at which the heat generation rate suddenly changes to the positive side in the vicinity of the fuel injection timing of the main injection Mn in the waveform of the heat generation rate (data transition). In addition, the main ignition timing can be detected with high accuracy even when the transition of the heat generation rate (time change) changes from negative to positive in the vicinity of the fuel injection timing of the main injection Mn.

  Further, the occasional heat generation rate sequentially calculated by the heat generation rate calculation unit B1 is also used in the pilot heat generation amount calculation unit B21 of FIG. That is, the pilot heat generation amount calculation unit B21 calculates the heat generation amount (total heat amount) generated by the pilot injection Pt based on the heat generation rate at each time sequentially calculated by the heat generation rate calculation unit B1. This parameter is used in the process of FIG. 8 (step S34), and will be described in detail later.

  Thus, when the main ignition timing t10 is detected and it is determined in step S21 that the main ignition timing is detected, the process proceeds to the subsequent step S22. In this step S22, thresholds TH11 and TH12 are determined (set) based on the target ignition timing for each main injection. Specifically, an appropriate value (optimum value) within an allowable range (lower and upper threshold values) is obtained in advance by experiments or the like in time units (for example, “second (sec)” units), and a predetermined storage device (for example, EEPROM in ECU 80). Store it in. In step S22, the time unit allowable ranges (lower and upper thresholds TH11 and TH12) are read from the storage device and converted into crank angle units on the basis of the engine speed at that time to advance the target ignition timing. Set the angle side and retard side respectively.

  In the subsequent step S23, the main ignition timing (timing t10) detected in the previous step S21 is within the allowable range (TH11 to TH12) set in step S22 (threshold value TH11 ≦ t10 ≦ threshold value TH12). ) Or not. If it is determined in step S23 that it is not within the same range, in the subsequent step S24, the main injection timing control unit B12 (first correction means) in FIG. 9 outputs the output of the in-cylinder pressure sensor 28. A command value relating to the execution timing (injection start timing) of the main injection Mn in a direction in which the detected value (timing t10) of the main ignition timing obtained from the above is within the allowable range (TH11 to TH12) (FIG. ) Is corrected (specifically, the correction coefficient K11 is updated). In step S25, the ignition timing control execution flag F1 is set to “0”, and the series of processes in FIG. The correction coefficient K11 update process (step S24) is performed in such a manner that the correction coefficient K11 is cumulatively increased or decreased (changed) by a predetermined amount (predetermined change amount). Specifically, for example, in the first update in which it is determined in step S23 that the main ignition timing is not within the allowable range, a predetermined map (for example, a variation map using the engine speed and the engine load as parameters) is displayed. Set the amount of change based on this. Then, when it is continuously determined in step S23 that it is not within the range, the number of continuous updates increases as the number of determinations in step S23 (particularly, determination that it is not in the range) is repeated. The smaller the amount of change. For example, the change amount is set (sequentially updated) as a value obtained by multiplying the map value by a predetermined magnification, and the magnification is set to “1/2”, “1/4”, “1/8”,. As ((1/2) ^ n, n is the number of continuous updates), the amount of change (update amount) of the correction coefficient K11 is successively decreased by setting the magnification to be smaller as the number of continuous updates increases.

  By repeatedly performing the process of FIG. 7, until the main ignition timing detected in the previous step S21 falls within the allowable range (TH11 to TH12), the basic injection map and the correction coefficient (such as the correction coefficient K11). The main injection is performed through the step S13 shown in FIG. 3 based on the command value set in step S13, and the correction coefficient K11 is updated through the steps S22 to S24 each time the main ignition timing is detected in the previous step S21. Will be. Then, the command value (first command value) of the main injection execution timing is corrected by the correction coefficient K11 in step S12 of FIG.

  As described above, even when it is determined in the previous step S23 that the main ignition timing is not within the allowable range, the process of step S24 is repeatedly performed, so that the main ignition timing is controlled to be within the allowable range. Will be. If it is determined in step S23 that the main ignition timing is within the allowable range, in step S231, the ignition timing control execution flag F1 is set to “1”, and the process shown in FIG. A series of processing ends.

On the other hand, in the process of FIG. 8, first, through steps S31 to S33,
-"1" is set to the ignition timing control execution flag F1 (step S31).
The correction coefficient K11 updated in the previous step S24 is not within the predetermined allowable range (first allowable range) (absolute value | K11 |> determination value TH13, step S32). The determination value TH13 is set in a manner according to the above threshold values TH11 and TH12 (step S22 in FIG. 7) or as a predetermined fixed value.
The correction coefficient K12 updated in step S34 (described later) is within a predetermined allowable range (second allowable range) (absolute value | K12 | ≦ determination value TH14, step S33). The determination value TH14 is set in a manner according to the above-described threshold values TH11 and TH12 (step S22 in FIG. 7) or as a predetermined fixed value.
It is determined whether or not these three conditions are satisfied at the same time. If it is determined that these conditions are satisfied at the same time, it is determined that execution of the main ignition timing control is necessary, and the process proceeds to step S34.

  In subsequent step S34, the pilot injection amount control unit B22 (second correction unit) in FIG. 9 determines whether the correction coefficient K11 is on the retard side or the advance side of the allowable range (first allowable range), that is, The detection value of the main ignition timing obtained from the output of the in-cylinder pressure sensor 28 according to the sign of the correction coefficient K11 (“positive = correction coefficient to the retard side” or “negative = correction coefficient to the advance side”) ( The command value (second command value) related to the injection amount of the pilot injection Pt is corrected so as to move the timing t10) to the retard side or the advance side in the same direction (specifically, the correction coefficient K12 is updated). That is, if the sign of the correction coefficient K11 is “positive (+)”, the injection amount of the pilot injection Pt is corrected to decrease to move the main ignition timing to the retard side, and the sign of the correction coefficient K11 is “negative (−)”. Then, the injection amount of the pilot injection Pt is increased and corrected so as to move the main ignition timing to the advance side. In step S39, the ignition timing control execution flag F1 is set to “0”, and the series of processes in FIG. 8 ends. The correction coefficient K12 is updated in such a manner that the correction coefficient K12 is cumulatively increased or decreased (changed) by a predetermined amount (predetermined change amount). Specifically, for example, in the first update in which it is determined in step S33 that the correction coefficient K12 is within the allowable range, it is calculated by a predetermined map, for example, the pilot heat generation amount calculation unit B21 of FIG. The amount of change at that time is set based on a change amount map using the amount of heat generated by the pilot injection Pt as a parameter. Then, if it is continuously determined in step S33 that it is within the range after that, for example, in a manner similar to step S24 of FIG. 7, the amount of change is reduced as the number of continuous updates increases.

  On the other hand, if it is determined in steps S31 and S32 that the conditions of each step are not satisfied, the execution of the main ignition timing control is not necessary, and in step S39, the ignition timing control execution flag F1 is set to “0”. ”Is set (F1 = 0), and the series of processes in FIG. If it is determined in step S33 that the condition in step S33 is not satisfied, in step S35, another parameter (predetermined command value of a predetermined actuator) that is neither the main injection execution timing nor the pilot injection amount is used. It is determined whether or not the main ignition timing control can be performed. Specifically, for example, for one or a plurality of predetermined parameters, a permissible range is provided for each parameter, and whether or not the main ignition timing control required within each permissible range can be performed for each parameter. to decide. For example, a command value for the bypass valve 61c (FIG. 1) or the like can be used as this parameter. That is, by adjusting (variably setting) the intake air temperature while varying the state of the bypass valve 61c (selection path and valve opening), the in-cylinder temperature at the time of ignition (the main ignition timing moves to the advance side as the temperature increases) Can be variably controlled.

  If it is determined in step S35 that the main ignition timing control can be performed (there is a parameter that enables the main ignition timing control), in the subsequent step S351, the parameter (if there are a plurality of parameters). The main ignition timing control is performed in accordance with a preset high priority order). On the other hand, if it is determined in step S35 that the main ignition timing control cannot be performed, in a subsequent step S352, a predetermined fail-safe process (for example, a process for storing a diagnosis code in an EEPROM or the like or a predetermined warning light is turned on) To execute the process.

  According to the process of FIG. 8, when the correction coefficient K11 updated in the process of FIG. 7 is not within the allowable range, the process of step S34 is performed, whereby the correction coefficient K12 is updated. Therefore, the command value (second command value) relating to the injection amount of the pilot injection Pt is corrected in step S12 of FIG. 3 by the correction coefficient K12, and the main injection is performed at the main injection execution timing corresponding to the correction coefficient K11. For the injection Mn, the main ignition timing moves in the same direction (advanced angle side or retarded angle side) as the sign of the correction coefficient K11. Accordingly, in step S23 of FIG. 7, the detected value of the main ignition timing with a correction coefficient K11 (smaller absolute value | K11 |) closer to the matching value of the basic injection map (step S12 of FIG. 3). It is determined that (timing t10) is within an allowable range (TH11 ≦ t10 ≦ TH12). Therefore, by repeatedly performing the processes of FIGS. 7 and 8, the correction coefficient K11 (and thus the main injection timing by the injector 27) is automatically converged within the allowable range.

  As described above, according to the combustion control device and the engine control system of the compression ignition type cylinder injection engine according to the present embodiment, the following excellent effects can be obtained.

  (1) a compression ignition engine 10 (internal combustion engine) that ignites and burns fuel in the combustion chamber 16 in the cylinder 12 based on compression and generates power (torque) on the output shaft (crankshaft) by the combustion; The present invention is applied to an engine system including an injector 27 (fuel injection valve for in-cylinder injection) that directly injects fuel into the combustion chamber 16 and controls the operation of various actuators in the system. This is the ignition timing (combustion start timing) of the main fuel injected by the main injection Mn for mainly generating power on the output shaft as a combustion control device (engine control ECU 80) of the compression ignition type cylinder injection engine. A program for detecting the main ignition timing (ignition timing detection means, step S21 in FIG. 7) and a detection value (timing t10) of the main ignition timing in a direction within a predetermined range (threshold value TH11 to threshold value TH12). A program (first correction means, step S24 in FIG. 7) for updating a correction coefficient K11 of a command value (first command value) of the main injection execution timing for the injector 27 (correcting the first command value); Whether or not the correction coefficient K11 updated in step S24 is within a predetermined range (first allowable range, -TH13 to + TH13) ( And a program for determining whether or not the first command value corrected by the correction coefficient K11 is within a predetermined range (determination means, step S32 in FIG. 8), and the correction coefficient K11 is within the range at step S32. If it is determined that the correction coefficient K11 (and thus the first command value) is on the retard side or the advance side of the tolerance range, when it is determined that the correction value K11 is not within the first tolerance range. Accordingly, the correction value K12 of the command value (second command value) related to the injection amount of the pilot injection Pt is so moved that the detection value (timing t10) of the main ignition timing is moved to the retard side or the advance side in the same direction. And a program for correcting the second command value (second correction means, step S34 in FIG. 8). With such a device, the robustness is enhanced, and it is possible to control the main ignition timing while keeping the main injection timing by the fuel injection valve in the vicinity of a predetermined range (first allowable range) basically. As a result, the combustion characteristics of the engine 10 (internal combustion engine), particularly the combustion characteristics related to the main ignition timing of the main fuel supplied by the main injection can be improved.

  (2) A series of processes such as the process in step S24 in FIG. 7 (process for updating the correction coefficient K11) and the process in step S32 in FIG. 8 (determination as to whether or not the correction coefficient K11 is within a predetermined range). The processing is configured to include a program that is repeated while a predetermined condition (for example, always during engine operation) is established. By doing so, every time the correction coefficient K11 (and hence the first command value) goes out of the allowable range (determined in step S32), the correction coefficient K11 is returned to the allowable range, and the main injection timing is automatically set. It converges within a predetermined allowable range (a range corresponding to the determination value TH13).

  (3) In step S34 of FIG. 8, whenever it is determined in step S32 that the correction coefficient K11 (and thus the first command value) is not within the allowable range, a command value (second command value) regarding the injection amount of the pilot injection Pt. ) Is changed cumulatively by a predetermined change amount. In this way, the main injection timing can be accurately converged within a predetermined allowable range (a range corresponding to the determination value TH13).

  (4) A program (cumulative determination means, step S33 in FIG. 8) for determining whether or not the integrated value of the change amount accumulated in step S34 in FIG. 8 exceeds the allowable upper limit, and the change amount integration in step S33 When it is determined that the value exceeds the allowable upper limit, main ignition timing control by correcting another parameter (for example, a command value for the bypass valve 61c) that is neither the main injection execution timing nor the pilot injection amount, and a predetermined failsafe It is effective to have a configuration including a program (steps S35, S351, and S352 in FIG. 8) that performs any one of the processes. With such a configuration, it is possible to more appropriately prevent or suppress inconvenience caused by the pilot injection amount deviation. When the main ignition timing can be controlled to an appropriate value with other parameters, the main ignition timing control is executed and when the control cannot be performed (there is no such command value), a predetermined failure is performed. It is possible to execute the safe process and notify the fact or take some countermeasures.

  (5) In step S34 of FIG. 8, among the command values for the injector 27 (fuel injection valve), the command value related to the injection mode of pilot injection (single stage preliminary sub-injection), more specifically, the command value related to the injection amount is corrected. I did it. By doing so, the main ignition timing control can be performed more easily and accurately.

  (6) The permissible range (first permissible range) used in step S32 in FIG. 8 is a predetermined reference value (first reference value, value on the basic injection map used in step S12 in FIG. 3) and its first. It was set as the range prescribed | regulated by the allowable deviation | shift amount (judgment value TH13) from 1 reference value. In step S32, the difference between the correction coefficient K11 updated in step S24 of FIG. 7 (and thus the first command value corrected by the correction coefficient K11) and the first reference value (value of the correction coefficient K11). The first command value is within the first allowable range when the deviation is smaller than the allowable deviation (correction of the pilot injection amount is not necessary). ) Judgment was made. In this way, the first allowable range can be set easily and appropriately.

  (7) As the first reference value, the initial value (the main injection map) of the injection control map (basic injection map) in which the command value for the injector 27 is associated with predetermined parameters (engine speed, engine load, etc.) related to the engine 10 In the embodiment, a fixed value) is used. As described above, the first reference value can be easily and appropriately set by using an injection control map (so-called adaptation map) generally stored in the ROM.

  (8) In step S21 of FIG. 7, the main ignition timing is detected based on the output of the in-cylinder pressure sensor. With such a configuration, the main ignition timing can be detected with high accuracy with a highly practical configuration.

  (9) At this time, based on the output of the in-cylinder pressure sensor 28, the data transition (so-called waveform) of the heat generation rate, which is the amount of heat generated per predetermined time (for example, unit time, unit output shaft rotational speed, etc.) is obtained ( 9, the main ignition timing is detected based on the obtained data transition together with the relational expression (formula 1) (for example, detected as the timing at which the heat generation rate suddenly changes to the positive side in the vicinity of the fuel injection timing of the main injection Mn). ) With such a configuration, it is possible to detect the main ignition timing with high detection accuracy.

  (10) A program (engine control means) for performing predetermined control (torque control or the like) related to the engine 10 based on the operation of various actuators (see FIG. 1) in the engine system is mounted on the ECU 80 together with the above programs. In addition to the ECU 80, the engine control system further includes various sensors and actuators (see FIG. 1). In such a configuration, the combustion characteristics are improved as described above, so that more reliable engine control can be performed.

  Here, when the command value for the main injection execution timing is changed to the advance side or the retard side (when the correction coefficient K11 is updated to the advance side or the retard side), the command is set in the same direction as the advance / retard direction. It is preferable to change the execution time of pilot injection by the same amount. Specifically, as shown in FIGS. 10A and 10B, when the main injection execution timing is advanced by x1 in the figure, the pilot injection execution timing is also advanced by x2 which is the same amount as x1 ( That is, x1 = x2.)

  According to this configuration, the interval between the pilot injection and the main injection (injection interval) can be maintained at a desired interval. Variations in the injection amount can be suppressed. The same applies when retarding the main injection timing.

  As a result, even when the pilot injection and the main injection are executed together, the main injection amount can be properly controlled and stabilized even if the execution timing of the main injection is changed to control the ignition timing of the main injection. Fuel injection control can be realized. In addition, when changing the execution timing of pilot injection to the advance side or the retard side by the same amount as the advance amount or retard side change amount of the main injection execution timing, it is necessary to set an interval for each engine operating condition. Therefore, the effect that the control can be easily performed can be realized.

  However, the maximum advance timing (advance side guard value) is set for pilot injection in order to ensure combustibility. Therefore, when the pilot injection timing reaches its maximum advance timing, it is desirable not to advance further, but to limit the pilot injection timing with the maximum advance timing. That is, in such a case, x1 <x2 is allowed in FIG.

(Second Embodiment)
Next, a second embodiment in which a combustion control device and an engine control system for a compression ignition type cylinder injection engine according to the present invention are embodied will be described with reference to FIGS. Note that the basic configuration of the apparatus and system of this embodiment also conforms to the configuration of the first embodiment shown in FIG. Therefore, here, for convenience of explanation, descriptions regarding common configurations and operations are omitted, and differences from the first embodiment are mainly described.

  As described above, if the time (main ignition delay time) from the execution (start) of main injection to the start of combustion (ignition) becomes too long, a large amount of fuel is burnt at once. Inconveniences such as heat generation and eventually noise occur. On the other hand, in the cylinder injection engine, since the fuel is directly injected into the cylinder, if the main ignition delay time becomes too short, the mixing time of the intake air and fuel in the combustion chamber (premixing time) Insufficient time cannot be secured and desired combustion characteristics cannot be obtained. In the present embodiment, as shown in FIG. 11, the main ignition delay time from the injection start timing of the main injection Mn (main injection execution timing, timing t21) to the combustion start timing of the main injection Mn (main ignition timing, timing t22). Paying attention to (time D20), in order to avoid the above inconvenience, pilots among the command values for the injector 27 are set so that the detected value at this time D20 becomes an appropriate value (contains within a predetermined allowable range). A command value related to the injection amount of the injection Pt is variably set. Here, the main ignition delay time becomes shorter as the injection amount (and hence the combustion amount) of the pilot injection Pt increases as shown in the graph of FIG.

  In the present embodiment, the process of FIG. 13 is executed instead of the processes of FIGS. 7 and 8 of the first embodiment. Hereinafter, the combustion control of this embodiment will be described with reference to FIG. Note that the series of processing shown in FIG. 13 is also basically performed at a predetermined processing interval (a period equivalent to the processing interval in FIG. (Sequentially). The values of various parameters used in the processing of FIG. 13 are also stored in a storage device such as a RAM, EEPROM, or backup RAM mounted on the ECU 80 as needed, and updated as needed.

  As shown in FIG. 13, in this series of processing, first in step S41, predetermined parameters, for example, the engine speed at that time (actually measured value by the crank angle sensor 71) and the accelerator operation amount at that time by the driver ( Further, the main injection timing (timing t21 in FIG. 11, for example, detected based on a command value for the injector 27) is read. In the subsequent step S42, the main ignition delay time is calculated based on the predetermined parameters included in the various parameters read in step S41 (the required torque including the loss due to the external load is separately calculated as necessary). The reference value DT1 (desired value) is acquired. Specifically, it is acquired using, for example, a predetermined map (which may be a mathematical expression) stored in a ROM or the like. As this map, for example, for each of the engine speed and the accelerator operation amount (or the required torque calculated based on the accelerator operation amount), the reference value DT1 conforming value (optimum value) corresponding to the magnitude thereof. However, what has been written in advance through experiments or the like can be used.

  In subsequent step S43, the main ignition timing (timing t22 in FIG. 11) is detected. Note that the detection (calculation) of the main ignition timing is similar to that in the first embodiment, while acquiring the in-cylinder pressure (actually measured value by the in-cylinder pressure sensor 28) and the relational expression ( Based on equation 1).

  In the subsequent step S44, based on the main injection timing (timing t21) acquired in the previous step S41 and the main ignition timing (timing t22) calculated in step S43, the detected value DT2 of the main ignition delay time (in FIG. 11). Time D20) is calculated. In the subsequent step S45, the difference (absolute value | DT1-DT2 |) between the reference value DT1 acquired in the previous step S42 and the detected value DT2 is compared with a predetermined determination value TH21, and the detected value DT2 is determined to be predetermined. Is determined to be within the allowable range (| DT1-DT2 | ≦ determination value TH21). The determination value TH21 is set in a manner according to the case of the threshold values TH11 and TH12 (step S22 in FIG. 7) in the first embodiment, or as a predetermined fixed value.

  If it is determined in step S45 that the detected value DT2 is not within the allowable range, in a subsequent step S451, a command related to the injection amount of the pilot injection Pt is set so that the detected value DT2 approaches the reference value DT1. The value (FIG. 6A) is corrected (specifically, the correction coefficient K21 is updated). That is, when the detection value DT2 is earlier than the reference value DT1 (positioned on the advance side), the injection amount of the pilot injection Pt is corrected to decrease so as to bring them closer together, and the detection value DT2 is later than the reference value DT1 ( If it is located on the retard side), the injection amount of the pilot injection Pt is corrected to increase (see FIG. 4). Then, with this correction coefficient update processing, this series of processing ends. The update of the correction coefficient K21 is, for example, in a manner similar to step S34 of FIG. 8 in the previous first embodiment, and the correction coefficient K21 is cumulatively increased or decreased by a predetermined amount (predetermined change amount). Changed).

  On the other hand, if it is determined in step S44 that the detected value DT2 is within the allowable range, the series of processes in FIG. 13 is terminated without updating the correction coefficient K21.

  According to the process of FIG. 13, the correction coefficient K21 is updated by performing the process of step S451 when the detection value DT2 updated in step S43 is not within the allowable range. For this reason, the command value (ignition delay command value) related to the injection amount of the pilot injection Pt is corrected in step S12 of FIG. 3 by the correction coefficient K21, so that the detected value DT2 (and thus the main ignition delay time) is the reference. It becomes possible to approach the value DT1. Then, by repeatedly performing the process of FIG. 13, the detection value DT2 (and thus the main ignition delay time) is automatically converged within the allowable range.

  As described above, according to the combustion control device and the engine control system of the compression ignition type cylinder injection engine according to the present embodiment, the following excellent effects can be obtained.

  (11) Program for detecting a main ignition delay time which is a time from when main fuel is injected by main injection Mn until the main fuel is ignited (combustion is started) (ignition delay time detecting means, step of FIG. 13) S41, S43, S44) and a command value (ignition delay command value) regarding the injection amount of pilot injection Pt are variably set based on the detected value, more specifically, the correction coefficient K21 is updated (ignition delay command value is changed). A program for correcting (ignition delay time control means, step S451 in FIG. 13). In such a configuration, the main ignition delay time is controlled to an appropriate value in step S451, and inconveniences (such as noise and insufficient premixing time) caused by excessive ignition delay time can be suitably prevented or suppressed. It becomes possible.

  (12) In step S451 of FIG. 13, among the command values for the injector 27 (fuel injection valve), the command value related to the injection mode of pilot injection (single stage preliminary sub-injection), more specifically, the command value related to the injection amount is corrected. I did it. By doing so, it becomes possible to control the main ignition delay time more easily and accurately.

  (13) As a program for detecting the main ignition delay time, a program for detecting the main injection start timing (injection timing detection unit, step S41 in FIG. 13) and a program for detecting the main ignition timing (ignition timing detection unit, in FIG. 13) Step S43) and a program for calculating the main ignition delay time (ignition delay time calculation unit, step S44 in FIG. 13) based on each detected value by these programs are used. . With such a configuration, it becomes possible to detect the main ignition delay time more easily and accurately.

  (14) In step S41 of FIG. 13, the main injection start timing is detected based on the command value for the injector 27. This makes it possible to detect the main injection start timing more easily and accurately.

  (15) In step S43 of FIG. 13, the main ignition timing is detected based on the output of the in-cylinder pressure sensor. With such a configuration, the main ignition timing can be detected with high accuracy with a highly practical configuration.

  (16) In step S451 of FIG. 13, the command value (ignition delay command value) regarding the injection amount of pilot injection Pt is varied so that the detection value DT2 of the main ignition delay time approaches the predetermined reference value (reference value DT1). I set it. Specifically, in step S45 of FIG. 13, it is determined whether or not the detection value DT2 is within a predetermined allowable range (a range determined by the reference value DT1 and the determination value TH21), and the detection value is within the allowable range. If not, in step S451, the command value related to the pilot injection amount is corrected in the direction in which the detected value falls within the allowable range. With such a configuration, even if the main ignition delay time (strictly, the detected value DT2) is out of the allowable range, the main ignition delay time is variably controlled within the predetermined allowable range by the process of step S451. It is possible to suitably prevent or suppress inconvenience due to the above-described ignition delay time shift.

  (17) A series of processes in FIG. 13 is configured to include a program that is repeatedly performed while a predetermined condition (for example, always during engine operation) is established. By doing so, the main ignition delay time is automatically converged within a predetermined allowable range.

  (18) A program (engine control means) for performing predetermined control (torque control or the like) related to the engine 10 based on the operation of various actuators (see FIG. 1) in the engine system is mounted on the ECU 80 together with the above programs. In addition to the ECU 80, the engine control system further includes various sensors and actuators (see FIG. 1). In such a configuration, the combustion characteristics are improved as described above, so that more reliable engine control can be performed.

(Third embodiment)
Next, a third embodiment of the present invention will be described. Since the basic configuration of the apparatus and system of the present embodiment is similar to the configuration of the first embodiment shown in FIG. 1, the description regarding the common configuration and operation is omitted.

  In this embodiment, the ignition timing feedback control is performed so that the actual ignition timing of the main injection coincides with the target ignition timing. Based on the deviation between the actual ignition timing of the main injection and the target ignition timing, Control the injection timing. In such ignition timing feedback control, when the ignition timing deviation of the main injection is greater than or equal to a predetermined value, or when the injection timing feedback control amount calculated based on the ignition timing deviation is greater than or equal to the predetermined value, pilot injection The correction is performed with respect to the injection amount.

  FIG. 14 is a flowchart showing the processing procedure of the fuel injection control process in the present embodiment. The series of processes shown in FIG. 14 is basically executed by the ECU 80 executing a program stored in the ROM. Sequentially executed at a predetermined processing interval (with a cycle equal to or faster than the processing interval of FIG. 3). Although illustration is omitted, the main injection amount and the pilot injection amount are calculated based on the engine operating state (accelerator operation amount and engine rotation speed) by different calculation processing.

  In FIG. 14, in step S51, the actual ignition timing of the main injection is detected. Note that the detection (calculation) of the actual ignition timing is similar to the detection value (t10) of the main ignition timing in the first embodiment, while obtaining the in-cylinder pressure (measured value by the in-cylinder pressure sensor 28) from time to time. This is performed based on the configuration of FIG. 9 and the relational expression (formula 1). In the subsequent step S52, a target ignition timing for main injection is calculated. At this time, for example, using the map data prepared in advance, the target ignition timing of the main injection is calculated based on the engine speed and the required load (for example, accelerator operation amount).

  In step S53, the main injection timing correction amount Km as a feedback control amount is calculated based on the deviation between the actual ignition timing of the main injection and the target ignition timing, and in the subsequent step S54, the main injection timing correction amount Km is calculated. Based on this, an injection timing command value for main injection is calculated. As the feedback calculation, a known PI calculation, PID calculation, or the like is used.

  Here, if the actual ignition timing of the main injection is on the retard side of the target ignition timing, a correction amount for shifting the main injection timing to the advance side is set as the main injection timing correction amount Km. If the actual ignition timing is closer to the advance side than the target ignition timing, a correction amount for shifting the main injection timing to the retard side is set as the main injection timing correction amount Km. For example, if the injection timing correction amount Km is to advance the injection timing, a negative value is set as the Km value. If the injection timing correction amount Km is to correct the injection timing, the Km value is set. Is set to a positive value.

  Thereafter, in step S55, it is determined whether or not the absolute value of the main injection timing correction amount Km (feedback correction amount) calculated in step S53 is greater than or equal to a predetermined threshold value THx. At this time, the threshold value THx is set based on the target ignition timing of the main injection at that time. However, the threshold value THx can be a fixed value.

  If | Km | ≧ THx, the process proceeds to step S56, and injection amount correction related to pilot injection is executed based on the main injection timing correction amount Km. At this time, the already set pilot injection amount is corrected to decrease or increase, and the injection amount command value is calculated. Specifically, with regard to this injection amount correction, if the main injection timing correction amount Km is a negative value (the actual ignition timing is later than the target and a value for advance correction), the pilot injection amount is corrected to increase. Further, if the main injection timing correction amount Km is a positive value (the actual ignition timing is earlier than the target and the value for delay correction), the pilot injection amount is corrected to decrease.

  Thereafter, in step S57, main injection and pilot injection are performed based on command value data (including the above-described injection timing command value) related to main injection and command value data (including the above-described injection amount command value) related to pilot injection. Execute.

  In step S55, if | Km | <THx, the main injection and the pilot injection are performed without executing the injection amount correction of the pilot injection based on the main injection timing correction amount Km.

  Instead of the main injection timing correction amount Km (feedback correction amount), it is also possible to determine whether or not the pilot injection amount needs to be corrected based on the ignition timing deviation of the main injection (= actual ignition timing−target ignition timing). It is. That is, when it is determined that the ignition timing deviation of the main injection is greater than or equal to a predetermined value, the pilot injection amount increase correction or decrease correction is executed. At this time, if the deviation in the ignition timing of the main injection corresponds to the actual ignition timing being later than the target, the pilot injection amount should be increased and the actual ignition timing to be earlier than the target. If so, the pilot injection amount is reduced.

  As described above, in the third embodiment, the actual ignition timing of the main injection can be advanced or delayed by increasing or decreasing the pilot injection amount. Therefore, even if the ignition timing deviation of the main injection or the ignition timing feedback control amount is large, it can be reduced. Thereby, it is possible to improve the combustion characteristics of the engine, particularly the combustion characteristics related to the ignition timing of the supplied fuel by the main injection.

  Since the threshold value THx for comparing the main injection timing correction amount Km (feedback correction amount) is set based on the target ignition timing of the main injection, the target ignition timing of the main injection is determined according to the engine operating state etc. Even if is changed, appropriate combustion characteristics can be realized each time.

  Here, when the execution timing of the main injection is changed to the advance angle side or the retard angle side, the execution timing of the pilot injection may be changed in the same direction as the advance / retard angle direction (see FIG. 10 described above). . In this case, for example, it is desirable to change the execution timing of pilot injection to the advance side or the retard side by the same amount as the advance amount or the retard side change amount of the main injection execution timing.

  According to this configuration, the interval between the pilot injection and the main injection (injection interval) can be maintained at a desired interval. Variations in the injection amount can be suppressed. The same applies when retarding the main injection timing.

  As a result, even when the pilot injection and the main injection are executed together, the main injection amount can be properly controlled and stabilized even if the execution timing of the main injection is changed to control the ignition timing of the main injection. Fuel injection control can be realized. In addition, when changing the execution timing of pilot injection to the advance side or the retard side by the same amount as the advance amount or retard side change amount of the main injection execution timing, it is necessary to set an interval for each engine operating condition. Therefore, the effect that the control can be easily performed can be realized.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  In the process of FIG. 7, a process similar to the process of step S32 of FIG. 8 is performed prior to the update process of the correction coefficient K11 in step S24 of FIG. If the correction coefficient K11 is out of the allowable range when updated, the correction coefficient K11 may not be updated in step S24. In this case, a program that performs a process similar to the process of step S32 prior to the process of step S24 corresponds to the “permission condition determination unit”.

  Further, the update process of the correction coefficient K11 is not prohibited, and the update process is limited (for example, the update amount is reduced) until a predetermined condition is satisfied (for example, the scheduled update value falls within the first allowable range). You may do it. By doing so, deterioration of combustion characteristics (noise, etc.) due to excessive correction can be prevented or suppressed more reliably.

  Further, in this case, the determination process performed prior to the update of the correction coefficient K11 in step S24 in FIG. 7 is not limited to the above determination process (a process similar to the process in step S32), and an optimum predetermined value according to the application or the like. It can be set as the process which judges the success or failure of permission conditions.

  8 is not performed. In the process of FIG. 7, prior to the process of step S24 of FIG. 7, the main ignition timing falls within a predetermined range wider than the allowable range (threshold value TH11 to threshold value TH12) used in step S23. If the main ignition timing falls within the range, it is determined that the difference between the main ignition timing at that time and the target value is sufficiently small, and step S24 in FIG. While processing (first control) is performed to bring the main ignition timing closer to the target value, if the main ignition timing is not within that range, the difference between the main ignition timing and the target value at that time is sufficiently small If not, the process of step S24 in FIG. 7 is performed (however, the update amount of the correction coefficient K11 is limited if necessary) and the process of step S34 in FIG. Control is performed) may be closer to the main ignition timing to the target value. In this case, a program for performing a series of processes related to the control corresponds to a “control unit”. With such a configuration, it becomes possible to suitably prevent or suppress deterioration in combustion characteristics (noise, etc.) due to excessive control deviation.

  The update mode of the correction coefficients K11, K12, and K21 in the above embodiments is not limited to the above mode and is arbitrary. For example, in order to simplify the program, it may be changed cumulatively by a fixed change amount.

  In each of the above embodiments, the in-cylinder pressure sensor is provided for each cylinder, but this sensor is provided only for some cylinders (for example, one cylinder), and other cylinders are estimated based on the sensor output. A value may be used. If the cylinder pressure sensor is not provided in all cylinders but only in some cylinders, the cylinder pressures of other cylinders are measured using the measured values of cylinder pressures obtained with the cylinders with cylinder pressure sensors. It is effective to adopt a configuration that estimates the internal pressure. By doing so, the in-cylinder pressure of many cylinders can be measured while suppressing the number of sensors and calculation load as much as possible.

  In addition, the in-cylinder pressure may be estimated from other parameters without providing the in-cylinder pressure sensor at all. For example, the pressure in the cylinder 12 (cylinder pressure) generally changes as shown in FIG. 15 in one combustion cycle. That is, the in-cylinder pressure becomes the highest in the vicinity of TDC (top dead center), and decreases at a distance from the pressure peak (maximum point) at least in the vicinity of TDC. Along with such a crank angle, the in-cylinder pressure corresponding to each state is mapped for each state defined by the values of other parameters that affect the in-cylinder pressure (particularly those that have a large effect). Then, the in-cylinder pressure can be estimated based on each value of the mapped parameter. Incidentally, as the in-cylinder pressure increases, the combustion rate (corresponding to the ease of combustion), which is the amount of heat per unit fuel amount generated by burning the fuel, also increases.

  In the first embodiment, in order to set the allowable range to a more appropriate range, threshold values TH11 and TH12 are prepared in the storage device in units of time, and converted into units of crank angle in step S22. did. However, the present invention is not limited to this, and thresholds TH11 and TH12 may be prepared in units of crank angle from the beginning. By doing so, it is possible to omit the conversion processing to the crank angle unit.

  Further, as shown in FIG. 16, the data transition (so-called waveform) of the heat release rate changes according to the engine load (for example, detected as a required torque that is a basis for determining command values of various actuators in torque control). That is, when the load is high, as shown by the solid line L31 in the figure, a rapid change in the heat generation rate is observed at the main ignition timing (change to the increase side), but at a low load, the change is gentle. Become. Therefore, it becomes difficult to detect the main ignition timing with high accuracy at low load. Therefore, it is also effective to variably set the thresholds TH11 and TH12 based on the engine load at that time, for example, a configuration in which the allowable range is widened as the engine load is lower. The same applies to the allowable range related to the main ignition delay time of the second embodiment.

  In each of the above embodiments, when it is determined that normal control should not be performed, main ignition is performed by correcting (changing) the command value related to the pilot injection amount among the command values for the injector 27 as the next control. The timing and main ignition delay time are variably controlled. However, the present invention is not limited to this, and these may be variably controlled by another parameter. For example, even with the same prior sub-injection mode, parameters other than the injection amount, that is, command values related to the number of injection stages (including pre-injection in addition to pilot injection, etc.), injection timing, injection interval, etc. are corrected (changed). You may do it.

  Further, the command value for the actuators other than the injector 27 may be used as a second command value or an ignition delay command value in which the main ignition timing and the main ignition delay time are variable. Basically, any command value related to the combustion rate during the main injection (ease of fuel ignition in the combustion chamber 16) can be adopted as the second command value or the ignition delay command value. .

  For example, a command value that affects the in-cylinder temperature at the time of ignition or a command value that affects the in-cylinder pressure at the time of ignition can be used. When the intake air temperature is variably controlled, it is effective to employ a command value that makes the state of the bypass valve 61c (selection path or valve opening) variable as described above. In addition, when the system configuration to which the present invention is applied is changed and there is a similar valve in the system, a command value that makes the state of the valve variable can be used. That is, for example, instead of the EGR pipe 61 (the connection path of the intake / exhaust passage), a branch passage may be formed in the intake passage or the exhaust passage. Further, for example, a bypass passage (a bypass passage) may be provided for the intercooler 33 (corresponding to the cooling device similarly to the EGR cooler 63). Further, the present invention is not limited to two branch paths, and three or more branch paths may be formed. Furthermore, you may make it vary the heat radiation amount of those branch passages by conditions other than the presence or absence of a cooling device (for example, the kind of piping etc.). Further, when the distribution area (degree of closure) of the branch passage is variable, switching between closing and opening may be performed in a binary manner. Alternatively, a technique (low pressure EGR) that introduces a low-temperature inert gas by returning the exhaust gas upstream of the intake side compressor may be applied. Furthermore, the intake air temperature can be variably controlled by other methods without using the bypass passage. For example, the intake air temperature may be variable using a sub-radiator, an appropriate heater (for example, nichrome wire), or the like. In addition, the temperature of the intake air may be indirectly adjusted by changing the temperature of the EGR gas or the EGR rate without directly adjusting the temperature of the intake air. Also in this case, the temperature of the EGR gas can be made variable by using, for example, a sub-radiator or an appropriate heater.

  As the parameter related to the in-cylinder pressure at the time of ignition, for example, an engine having a variable compression ratio mechanism that has been developed recently, such as an eccentric crankshaft, can employ a command value related to the drive amount of the mechanism. In addition, for example, a command value that acts on a parameter (for example, a fresh air amount) related to the intake charging efficiency for the target cylinder is effective, and among them, a command that affects the intake pressure (intake pressure) for the target cylinder. It is particularly effective to use a value. When the intake pressure is variably controlled, it is effective to use a command value that makes the intake air supercharging amount variable, for example, through a supercharger that makes the supercharging amount variable. As a device (supercharger) that makes the supercharging amount variable, for example, a variable nozzle mechanism that makes the supercharging pressure (strictly speaking, the supercharging amount by the rotation of the turbine) variable by a geometric mechanism, etc. It is effective to use a turbocharger with a variable geometry mechanism attached to the turbocharger, a turbocharger equipped with an electric assist motor, a turbocharger equipped with an auxiliary compressor upstream or downstream of the compressor, and the like.

  It is also effective to use a command value relating to the drive amount of the ignition assist device composed of a glow plug or the like. A glow plug is an electric heater that heats a heating element provided at a predetermined part in a cylinder to locally raise the atmosphere in the cylinder, and is generally used to assist ignition at the start of a diesel engine or the like. ing. For this reason, the practicality of such a configuration is high. In recent years, an ignition auxiliary device that makes it easy to generate ignition by locally changing the atmosphere in the cylinder to the energy level increasing side by electromagnetic action of a laser or the like has been studied. Therefore, you may make it employ | adopt such an ignition assistance apparatus.

  In addition to this, for example, the combustion rate is controlled to a desired value by variable control of the valve opening of the swirl control valve, the discharge amount of the fuel pump 43, and the valve timing and valve lift amount by the variable valve device. You may do it.

  Further, a combination of the above-mentioned various command values including the command value related to the injection mode of the above-described preliminary sub-injection is appropriately used as the second command value and the ignition delay command value that make the main ignition timing and the main ignition delay time variable. You may make it use. In this case, for example, a configuration in which a plurality of types of command values are prepared in advance as command values related to the combustion rate is also effective. That is, in step S34 in FIG. 8, step S451 in FIG. 13, or step S351 in FIG. 8, some (one or more) of these plural types of command values are selected based on the engine operating conditions at that time. In addition, a configuration in which the above-described correction is performed on the selected one or more command values is effective.

  In each of the above embodiments, the main ignition timing is detected based on the in-cylinder pressure. However, the present invention is not limited to this, and a configuration in which a sensor for measuring the in-cylinder temperature and the in-cylinder gas composition is provided in the cylinder, and the heat generation rate and thus the main ignition timing is detected based on the sensor output. Further, based on at least one of predetermined intake parameters (for example, intake temperature, intake pressure, intake component information, etc.) and exhaust parameters (for example, exhaust temperature, exhaust pressure, exhaust component information, etc.), the heat generation rate, and thus A configuration for detecting the main ignition timing (for example, map estimation) is also possible.

  In the second embodiment, the main injection start timing is detected based on the command value for the injector 27 in step S41 of FIG. However, the detection mode of the main injection start timing is not limited to such a mode, and is arbitrary. For example, an engine operation state or the like (equivalent value of the command value) referred to when determining the command value is used instead of the command value. You may do it. Alternatively, detection may be performed based on a parameter indicating the operating state of the fuel injection valve (injector 27). For example, a configuration is conceivable in which a sensor for measuring the lift amount of the needle 27b (FIG. 2) is provided in the fuel injection valve (injector 27) and the main injection start timing is detected based on the sensor output. Alternatively, a configuration in which the main injection start timing is detected based on the degree of variation in rail pressure due to fuel injection, or a fuel pressure sensor is provided in the injector 27 itself (or in the vicinity thereof) in order to improve detection accuracy, and the fuel injection of the injector 27 is performed. A configuration is also conceivable in which the main injection start timing is detected based on the degree of fluctuation of the fuel pressure accompanying the.

  In the second embodiment, the main ignition delay time is detected based on the main injection start timing and the main ignition timing. However, the present invention is not limited to this. For example, a configuration in which main ignition delay time is directly detected (for example, map estimation) based on predetermined intake parameters (for example, intake temperature, intake pressure, intake component information, etc.) is also possible. .

  Each of the above sensors (in-cylinder temperature detection sensor, in-cylinder gas composition detection sensor, needle lift amount detection sensor, fuel pressure sensor in the vicinity of the injector, etc.) still has a sufficient sensor life. Although it has not yet been put into practical use (although some are used in tests, etc.), there is a possibility that it will be put into practical use (installed in commercially available automobiles, etc.) in the future.

  The timings and times (main injection start timing, main ignition timing, main ignition delay time, etc.) targeted for detection in each of the above embodiments and modifications can be substituted with parameters that correlate with the timing and time. Specifically, for example, a timing indicating a predetermined point (particularly, a predetermined point during main combustion) in the waveform of the heat generation rate, that is, a maximum point / minimum point (the direction of change of the data value from positive to negative or from negative to positive) Timing when the data value becomes maximum or minimum in a predetermined period, timing when the data value suddenly changes (or stabilizes) to the positive side or negative side, timing when the data value exceeds (or falls below) a predetermined threshold value (For example, a zero cross point) can be substituted.

  In the above embodiment, an example in which main injection and a smaller amount of pilot injection are executed as a plurality of fuel injections (multi-stage injection) executed during one combustion cycle of the engine has been described. The configuration may be such that the same amount of fuel injection is executed a plurality of times during one combustion cycle. In such a configuration, the ignition timing feedback control is executed to converge the fuel ignition timing to the target for the specific injection that is the second and subsequent fuel injections among the plurality of fuel injections. Then, it is determined that the ignition timing deviation between the actual ignition timing and the target for the specific injection (or the ignition timing feedback control amount calculated based on the deviation) is a predetermined value or more, and the ignition timing deviation or ignition timing feedback control is performed. When it is determined that any of the amounts is equal to or greater than a predetermined value, the injection amount may be changed for the previous injection immediately before the specific injection. Details are as described in the third embodiment.

  The system configuration shown in FIG. 1 is merely an example of a configuration to which the present invention can be applied, and is a control system for a compression ignition type in-cylinder injection engine (including a mixed compression ignition PCCI engine, an HCCI engine, and the like). Even when the configuration of FIG. 1 is changed as appropriate, the present invention can be applied basically in the same manner as the above embodiments. For example, in each of the above-described embodiments, the injector 27 having the structure as shown in FIG. 2 is employed. However, any structure of the fuel injection valve can be selected according to the application. That is, the present invention is not limited to an electromagnetically driven fuel injection valve using an electromagnetic solenoid as an actuator, and for example, a piezo injector using a piezoelectric element as a needle actuator may be employed. Further, the present invention is not limited to a hydraulically driven fuel injection valve that is binary-controlled by a pulse signal, and the needle lift amount, and hence the injection rate, can be continuously and directly variable according to the amount of drive current supplied. A direct-acting fuel injection valve (for example, a direct-acting piezo injector being developed in recent years) may be employed. Further, it may be a nozzle that opens and closes the injection hole itself with a needle, or may be a fuel injection valve of an outer opening type. When such a configuration change is made for each of the above-described embodiments, the details of the various processes (programs) described above are appropriately changed (design change) to an optimum form according to the actual configuration. Is preferred.

  In the embodiment and the modification, it is assumed that various kinds of software (programs) are used. However, similar functions may be realized by hardware such as a dedicated circuit.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows the outline of this system about 1st Embodiment of the combustion control apparatus of the compression ignition type cylinder injection engine which concerns on this invention, and the engine control system by which the apparatus is mounted. The internal side view which shows typically the internal structure of the fuel injection valve used for the system. The flowchart which shows the basic process sequence of the fuel-injection control which concerns on the same embodiment. (A) is a timing chart which shows each transition of the injection command with respect to a fuel injection valve, (b) is the state (needle lift amount) of a fuel injection valve. (C)-(e) is a timing chart which shows transition of a heat release rate, respectively, about the case where pilot injection (increase injection, reference injection, reduction injection) by three different types of injection is performed. The graph which shows the relationship between the fuel injection amount in a micro injection amount area | region, and a heat release rate. (A) And (b) is a timing chart which shows the ignition timing control aspect of 1st Embodiment, respectively. The flowchart which shows the process sequence of the process which concerns on the ignition timing control of the embodiment. The flowchart which shows the process sequence of the process which concerns on the ignition timing control of the embodiment. The block diagram which shows the part which concerns on the signal processing of the output of the in-cylinder pressure sensor of the combustion control apparatus which concerns on the 1st Embodiment according to a function. The time chart which shows the injection command signal of pilot injection and main injection. Regarding the second embodiment of the combustion control device for a compression ignition type in-cylinder injection engine and the engine control system on which the device is mounted according to the present invention, (a) and (b) are the same as those of the second embodiment. The timing chart which shows the ignition timing control mode. The graph which shows the ignition timing control aspect of the 2nd embodiment. The flowchart which shows the process sequence of the process which concerns on the combustion control of the embodiment. The flowchart which shows the process sequence of the fuel-injection control process in 3rd Embodiment. The graph which shows the modification of each said embodiment. The graph which shows the modification of each said embodiment. (A) And (b) is a timing chart which shows the operation | movement aspect about an example of the combustion control apparatus of the conventional compression ignition type cylinder injection engine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 16 ... Combustion chamber, 27 ... Injector (fuel injection valve), 28 ... In-cylinder pressure sensor, 27b ... Needle, 60 ... EGR apparatus, 61c ... Bypass valve, 80 ... ECU (electronic control unit).

Claims (14)

A compression ignition engine that ignites and burns fuel based on compression in a combustion chamber in a cylinder and generates power on the output shaft by the combustion, and for in-cylinder injection that directly injects the fuel into the combustion chamber An apparatus for controlling an operation of at least one actuator in the engine system, comprising:
An ignition timing detection means for detecting a main ignition timing which is an ignition timing of main fuel injected by main injection for mainly generating power on the output shaft, or a parameter correlated with this timing;
First correction means for correcting a first command value, which is a command value of the main injection execution timing for the fuel injection valve, in a direction toward the side where the detection value by the ignition timing detection means falls within a predetermined range;
Determining means for determining whether or not the first command value corrected by the first correcting means is within a first allowable range which is a predetermined range;
When it is determined by the determination means that the first command value is not within the first allowable range, the first command value for the first command value and the first allowable range is the late side and the early side of the first allowable range. Of the command values for the actuators in the system other than the first command value so as to move the detection value by the ignition timing detection means to the slow side or the fast side in the same direction according to which Second correction means for correcting a second command value which is a predetermined command value;
A combustion control apparatus for a compression ignition type in-cylinder injection engine.   The compression ignition type in-cylinder according to claim 1, further comprising means for repeatedly performing a series of processes such as a correction process by the first correction unit and a determination process by the determination unit while a predetermined condition is satisfied. Injection engine combustion control device.   The second correction unit is configured to cumulatively change the second command value by a predetermined change amount each time the determination unit determines that the first command value is not within the first allowable range. 2. A combustion control device for a compression ignition type cylinder injection engine according to 2. Cumulative determination means for determining whether or not an integrated value of the amount of change accumulated by the second correction means exceeds an allowable upper limit;
A predetermined command that is neither the first command value nor the second command value among the command values for the actuators in the system when the cumulative determination means determines that the integrated value of the change amount exceeds the allowable upper limit. Means for performing either one of main ignition timing control by value correction and predetermined fail-safe processing;
A combustion control device for a compression ignition type cylinder injection engine according to claim 3.   The compression ignition type according to any one of claims 1 to 4, further comprising pre-sub-injection execution means for performing pre-sub-injection for injecting fuel prior to execution of the main injection in one combustion cycle of the engine. In-cylinder injection engine combustion control device.   6. The compression ignition type in-cylinder injection according to claim 5, wherein the second command value is a command value related to an injection mode of preliminary sub-injection performed by the preliminary sub-injection execution unit among command values for the fuel injection valve. Engine combustion control device.   The compression ignition type according to claim 6, wherein the second command value is a command value related to an injection amount of single-stage pre-sub-injection performed by the pre-sub-injection execution unit among command values for the fuel injection valve. In-cylinder injection engine combustion control device.   A means for changing the execution timing of the preliminary sub-injection in the same direction as the advance / retard direction when the main injection execution timing is corrected to the advance side or the retard side by the first correction unit. A combustion control apparatus for a compression ignition type cylinder injection engine according to any one of claims 5 to 7.   The combustion control device for a compression ignition type in-cylinder injection engine according to any one of claims 1 to 5, wherein the second command value is a parameter that affects the ease of fuel ignition in the combustion chamber. The first allowable range used in the determination means is a range defined by a predetermined first reference value and an allowable deviation amount from the first reference value,
The determination means determines whether or not a deviation amount between the first command value corrected by the first correction means and the first reference value is smaller than the allowable deviation amount, and the deviation amount is an allowable deviation amount. The combustion control device for a compression ignition type in-cylinder injection engine according to any one of claims 1 to 9, wherein the first command value is determined to be within a first permissible range when the value is smaller than.   The compression ignition system according to claim 10, wherein the first reference value used in the determination means is an initial value of an injection control map in which a command value for the fuel injection valve is associated with a predetermined parameter relating to the engine. In-cylinder injection engine combustion control device. The cylinder is provided with an in-cylinder pressure sensor that outputs a detection signal corresponding to the pressure in the combustion chamber,
The compression ignition type in-cylinder according to any one of claims 1 to 11, wherein the ignition timing detection means detects a main ignition timing or a parameter correlated with the timing based on an output of the in-cylinder pressure sensor. Injection engine combustion control device.   The ignition timing detection means obtains the data transition of the heat generation rate, which is the amount of heat generated per predetermined time, based on the output of the in-cylinder pressure sensor, and at the main ignition timing or this timing based on the obtained data transition. The combustion control device for a compression ignition type in-cylinder injection engine according to claim 12, which detects a correlated parameter. A combustion control device for a compression ignition type cylinder injection engine according to any one of claims 1 to 13 , an actuator in the engine system to be controlled by the combustion control device, and an operation of the actuator Engine control means for performing predetermined control related to the engine.

Images