JP2008175065A - Engine control device and fuel property detection device - Google Patents

Abstract

An engine control device and a fuel property detection device are provided that make it possible to realize a better combustion state by reducing deterioration of combustion that is likely to occur particularly at the time of engine start.
When an engine control device (an ECU for engine control) performs fuel injection in a start injection control period t12 to t14 from a predetermined start timing t12 at the time of engine start to an end timing t14 when a predetermined condition is satisfied. And a program for controlling the fuel injection amount to a target value determined based on the pressure in the cylinder (cylinder pressure). Specifically, during the start injection control period t12 to t14, the combustion state is monitored (monitored), and the fuel amount is controlled to an appropriate value each time.
[Selection] Figure 7

Description

  The present invention relates to an engine control device and a fuel property detection device that are suitable for improving emissions particularly at the time of engine start.

  In engine control, if the level of heavy and light fuel used and the engine control characteristics are not sufficiently matched, it will not be possible to control to the desired air-fuel ratio, or ignition will not be performed at the desired ignition timing. As a result, there is a concern about deterioration of drivability (operability) and emission (exhaust gas purification). This is because the specific gravity and volatility of the fuel, the charging efficiency, the exhaust component, and the like change according to the degree of heavy and light fuel. In particular, when the gasoline becomes heavier, the air-fuel ratio at the time of starting the engine increases the amount of fuel adhering to the intake pipe inner wall (cylinder inner wall in the case of in-cylinder injection) due to a decrease in volatility. When the weight is reduced, the fuel adhesion amount decreases and the fuel becomes richer.

  Therefore, conventionally, as in the device described in Patent Document 1, for example, a device has been proposed in which the degree of heavyness and lightness of the fuel used is reflected in the fuel injection control to suppress the deterioration of drivability and emission. The outline of this apparatus will be described with reference to FIG. Here, as an example, description will be given assuming that this device is applied at the time of engine start.

The transition of the engine speed indicated by the solid line L50 in FIG. 8A shows the case where the fuel used is normal fuel (fuel that is neither light nor heavy with respect to the standard light and light degree). This corresponds to the engine start characteristic (rotational speed characteristic). On the other hand, when the fuel used is a heavy fuel, the engine speed is a value at the time of normal fuel (as indicated by alternate long and short dash lines L51 and L52 (two examples) in FIG. 8A). It will be lower than the solid line L50). Therefore, in the apparatus described in Patent Document 1, a heavy / light sensor is provided in the fuel supply pipe and the fuel tank so that the heavy / light degree of the used fuel can be detected, and fuel injection is performed according to the detected heavy / light degree of the used fuel. The amount is corrected. That is, when the fuel used is normal fuel, a normal engine speed is obtained, and therefore, as shown by the solid line L53a in FIG. 8B, the fuel injection amount is not increased. On the other hand, when the fuel used is heavy fuel, it is determined that the engine output is insufficient, and the fuel injection amount is increased as shown by a one-dot chain line L53b in FIG. 8B. As a result, the engine torque increases, and as a result, the engine rotation speed gradually increases as indicated by alternate long and short dash lines L51 and L52 in FIG. This fuel increase correction is executed in the engine start period (predetermined period before warm-up), that is, the period t51 to t52.
JP-A-3-179150

  However, even the apparatus described in Patent Document 1 has not yet achieved good emission characteristics on a regular basis. Specifically, with this device, it is difficult to set the execution period of fuel increase correction (periods t51 to t52 in FIG. 8) to an appropriate length, and the execution period is set to be longer than the appropriate value. There is concern that emissions will deteriorate.

  The present invention has been made in view of such circumstances, and particularly provides an engine control device and a fuel property detection device that can realize a better combustion state by reducing deterioration of combustion that is likely to occur at the time of engine start. The main purpose is to do.

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

  According to the first aspect of the present invention, there is provided an engine control apparatus for rotating an output shaft by generating torque on the output shaft of the engine through combustion of fuel in a cylinder of the target engine, and at the time of starting the engine When the fuel to be used for combustion is injected and supplied in the start injection control period from the predetermined start timing to the end timing when the predetermined condition is satisfied, the pressure is determined based on the pressure in the cylinder (cylinder pressure). The fuel injection control means for controlling the fuel injection amount to the target value is provided.

  The inventor found that the fuel property can be detected based on the in-cylinder pressure, and invented the above configuration. Specifically, if there is an abnormality (deviation from the normal value) in the fuel property, it appears in the combustion state. For this reason, the fuel property can be estimated from the in-cylinder pressure indicating the combustion state with high accuracy. The relationship between the combustion state (in-cylinder pressure) and the fuel properties is slightly different depending on the type and specification of the engine or the type of fuel. However, if the conditions are constant, there is basically a uniform relationship. can get. Normally, particularly at the time of starting the engine, if there is an abnormality (for example, a heavy fuel property), the engine output decreases. In the above configuration, it is possible to perform (suitable) injection control according to the current in-cylinder pressure through the fuel injection control means by using such characteristics. That is, as described above, even when the fuel increase correction is performed at the time of starting the engine, the combustion state is monitored (monitored) and the fuel amount and ignition timing (in the case of a spark ignition type engine) are controlled to appropriate values. Alternatively, the correction execution period can be minimized. As a result, it is possible to realize a better combustion state by reducing the deterioration of combustion at the time of starting the engine due to the fuel properties and the like, and to improve the emission and drivability.

  According to a second aspect of the present invention, in the apparatus according to the first aspect, when the engine is a multi-cylinder engine that burns the fuel in a plurality of cylinders, the pressure in the cylinder, Alternatively, there is provided an average value calculating means for calculating an average value per cylinder of the multi-cylinder engine for another parameter using the pressure (for example, a parameter in the middle of calculating the target value of the fuel injection amount from the in-cylinder pressure). The fuel injection control means controls the fuel injection amount to a target value determined based on the average value calculated by the average value calculation means. With such a configuration, errors due to variations between cylinders are reduced, and the target value of the fuel injection amount for realizing a good combustion state can be acquired as a more accurate value.

  According to a third aspect of the present invention, in the apparatus according to the first or second aspect, the fuel injection control means further comprises combustion parameter acquisition means for converting the pressure in the cylinder into another parameter indicating a combustion state. Is characterized in that the fuel injection amount is controlled to a target value determined based on a combustion parameter as a conversion value acquired by the combustion parameter acquisition means.

  For example, depending on the application and specifications of the device (especially the type of the target engine), the same fuel is used for combustion parameters other than the in-cylinder pressure rather than controlling the fuel injection amount for the target value obtained directly from the in-cylinder pressure. It may be preferable to control the injection amount. In this regard, with the above configuration, the target value based on the combustion parameter can be obtained by the target fuel amount acquisition means, and the fuel injection amount can be controlled to the target value based on the combustion parameter by the fuel injection control means. Become.

  In this case, the in-cylinder pressure is sequentially stored in association with the engine operating conditions (elapsed time from cranking or accelerator operation amount) and the engine operating state (engine speed, engine load, cylinder temperature, etc.). A configuration (preferably stored in a nonvolatile manner) is particularly effective. With such a configuration, it becomes easy to obtain the combustion parameters with high accuracy based on the in-cylinder pressure data accumulated (sequentially stored).

  Further, in the invention according to claim 3, as the combustion parameter, as in the invention according to claim 4, the combustion end timing, the combustion period (the period from ignition to extinguishing), and the combustion center of gravity (If misfire is the degree of combustion “0%” and complete combustion is the degree of combustion “100%”, the heat generation rate of the combustion degree “50%” corresponds to the center of gravity of combustion), and at least the peak timing of the heat generation rate A configuration using one is effective. These combustion parameters are generally used as parameters indicating the combustion state, and are particularly important. Therefore, the configuration for controlling the fuel injection amount in accordance with these combustion parameters, that is, the above-described configuration is particularly effective in obtaining a good combustion state required for practical use.

  According to a fifth aspect of the present invention, in the apparatus according to any one of the first to fourth aspects, a correction coefficient for obtaining a correction coefficient for the basic target value of the fuel injection amount based on the pressure in the cylinder. An acquisition means is provided, wherein the fuel injection control means controls the fuel injection amount to a target value determined based on the correction coefficient acquired by the correction coefficient acquisition means.

  If only the deviation from the good combustion state (combustion deviation) is corrected, it is possible to maintain the good combustion state. In this respect, with the above configuration, the fuel injection control means reflects a correction coefficient based on the pressure in the cylinder to a predetermined basic value (basic target value) (for example, addition, subtraction, division, multiplication, etc.) By doing so, it becomes possible to perform fuel injection control that accurately compensates for the combustion deviation, and as a result, a good combustion state can be realized more easily and accurately.

  In this case, as in the invention described in claim 6, it is particularly effective that the correction coefficient related to the target value of the fuel injection amount corrects the fuel injection amount to be increased.

  As illustrated in FIG. 8, when the fuel used becomes heavier, the engine rotation speed tends to decrease when the engine is started. And at present, this is a particularly alarming issue. Therefore, practically, a configuration in which the fuel injection amount is corrected to be increased as in the configuration described in claim 6 is particularly useful.

  Furthermore, as a more specific configuration for realizing the configuration according to claim 6, as in the invention according to claim 7, the fuel injection control means reduces the initial increase value by a predetermined amount of decrease. In the aspect, the injection control in the start injection control period is performed, and the correction coefficient related to the target value of the fuel injection amount determines at least one of the initial increase value, the decrease end timing, and the decrease degree. Is beneficial.

  Further, when the correction of the fuel injection amount is performed in a binary manner (for example, the apparatus illustrated in FIG. 8 above), any one of the above claims 5 to 7 is provided as in the invention according to claim 8. In the apparatus according to any one of the preceding claims, it is effective to include a correction execution period varying unit that varies the length of the correction execution period with respect to the basic target value of the fuel injection amount based on the pressure in the cylinder. is there. With such a configuration, it becomes possible to set the length of the fuel injection amount correction execution period to an appropriate length based on the in-cylinder pressure, so that good emission characteristics can be obtained constantly. become.

  By the way, the possibility that the fuel property of the fuel used changes rapidly during the start-up period is extremely low. The inventor makes use of such characteristics in the apparatus according to claim 9, that is, the apparatus according to any one of claims 1 to 8, wherein the fuel is based on the pressure in the cylinder by the fuel injection control means. A device characterized by further comprising control execution means for determining whether or not to perform injection control based on a pressure value in the cylinder in a determination period provided before the start injection control period. If it is such a structure, the apparatus as described in any one of the said Claims 1-8 will be implement | achieved by simple control.

  Further, the fuel properties (especially the degree of heavyness) of the fuel used have a particularly great influence on the fuel injection control, such as the aforementioned fuel adhesion. Therefore, such information on the fuel properties is particularly effective as reflected above in the fuel injection control, particularly the fuel injection amount. However, the engine speed (output torque) can be recovered (increased) when the engine is started as long as the engine output (output torque) can be controlled even with other parameters, not limited to the fuel injection amount. It is. That is, as in the invention according to claim 10, in the engine control device that rotates the output shaft by generating torque in the output shaft of the engine through the combustion of fuel in the cylinder of the target engine, When the fuel to be used for combustion is injected and supplied in the start injection control period from the predetermined start timing at the start to the end timing when the predetermined condition is satisfied, the target value determined based on the pressure in the cylinder is set. If equipped with a torque control means for controlling the parameter related to the magnitude of the generated torque, it is possible to reduce the deterioration of combustion at the start of the engine due to fuel properties and realize a better combustion state become.

  As an apparatus using a parameter other than the fuel injection amount, for example, as in the invention according to claim 11, in the apparatus according to claim 10, the engine performs fuel ignition with a predetermined ignition method. It is a spark ignition type engine that performs the ignition of the above, and a device in which the parameter relating to the magnitude of the torque is the ignition timing is effective.

  However, the parameter related to the magnitude of the torque in the apparatus according to claim 11 is not limited to the fuel injection amount and the ignition timing. Examples of such parameters include charging efficiency (for example, supercharging amount, fresh air amount, intake air temperature, etc.), EGR (exhaust gas recirculation) amount, intake / exhaust valve timing / valve lift amount, glow plug, etc. It is possible to use an arbitrary parameter such as a driving amount.

  Further, in view of the fact that the fuel property can be detected based on the in-cylinder pressure described above, the torque is generated in the output shaft through the combustion of the fuel in the cylinder as in the invention described in claim 12. A device having a fuel property detecting means for detecting a fuel property (a fuel property that affects the combustion state) based on the pressure in the cylinder (cylinder pressure) of the engine that rotates its output shaft, that is, a fuel property detection It is also useful as a device. According to such an apparatus, it becomes possible to easily measure the fuel properties with relatively high accuracy. The detected fuel property can be used for purposes other than engine control.

  Hereinafter, an embodiment in which an engine control device and a fuel property detection device according to the present invention are embodied will be described with reference to FIGS. In addition, as each apparatus according to the present embodiment, as in the apparatus illustrated in FIG. 8 above, the one that suppresses deterioration of drivability and emission by reflecting the degree of heavy and light fuel used in the fuel injection control. Assumed. Here, as an example, a case will be described in which these devices are incorporated in a system (engine control system) that performs engine control specifically for a reciprocating engine (internal combustion engine) for a four-wheeled vehicle.

  First, the configuration of this system will be described in detail with reference to FIG. FIG. 1 is a configuration diagram showing an outline of a vehicle control system to which the engine control device and the fuel property detection device according to this embodiment are applied. As an engine of the present embodiment, a multi-cylinder (for example, four-cylinder) engine is assumed. However, in FIG. 1, only one cylinder (cylinder) is illustrated for convenience of explanation.

  As shown in FIG. 1, the engine control system controls an engine 10 (internal combustion engine) that rotates an output shaft (crankshaft) (not shown) by torque generated through combustion in a cylinder 12. 10 and various sensors for controlling 10 and an ECU (electronic control unit) 40 and the like.

  The engine 10 to be controlled here is a spark ignition type reciprocating engine, and basically includes a cylinder (cylinder) 12 formed by a cylinder block 11. The cylinder block 11 is provided with a cooling water channel 11a for circulating the cooling water in the engine 10 and a water temperature sensor 11b for detecting the temperature (cooling water temperature) of the cooling water in the water channel 11a. The engine 10 is cooled by water. A piston 13 is accommodated in the cylinder 12, and a crankshaft as an output shaft (not shown) is rotated by the reciprocating motion of the piston 13. A crank angle sensor 41 that outputs a crank angle signal is provided for each predetermined crank angle (for example, in a cycle of 30 ° CA) on the outer peripheral side of the crankshaft. The crankshaft rotation angle and rotation speed (engine rotation speed) ) Can be detected. 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 upper surface of the piston 13.

  The cylinder head 15 is formed with an intake port 17 and an exhaust port 18 that open to the combustion chamber 16, and the intake port 17 and the exhaust port 18 are cams attached to camshafts that are linked to the crankshaft ( It is opened and closed by an intake valve 21 and an exhaust valve 22 which are driven by an unillustrated). The intake port 17 is connected to an intake pipe 23 (intake manifold) for sucking outside air (fresh air) into each cylinder of the engine 10, and combustion gas (from each cylinder of the engine 10) is connected to the exhaust port. An exhaust pipe 24 (exhaust manifold) for discharging (exhaust) is connected. An air flow meter 25 is provided inside the intake pipe 23 for measuring the amount of fresh air drawn through the air cleaner at the most upstream part of the intake pipe 23. Further, on the downstream side of the air flow meter 25, an electronically controlled throttle valve 26 (intake throttle valve) whose opening degree is electronically adjusted by an actuator such as a DC motor, and an opening degree of the throttle valve 26 (throttle valve). And a throttle opening sensor 26a for detecting movement (opening fluctuation).

  An electromagnetically driven (or piezo-driven type) injector 27 (fuel injection valve) for injecting and supplying fuel is attached to the intake port 17. Such an injector is provided for each cylinder. Thus, fuel (gasoline) is supplied (port injection) to these intake passages, particularly to the intake ports of the cylinders, by these injectors.

  In the engine 10, the fuel is combusted by igniting the fuel injected by the injector (strictly, the mixture with intake air). For this reason, a spark plug 28 is attached to the cylinder head of the engine 10 for each cylinder. That is, when the engine 10 is ignited, the ECU 40 applies a high voltage to the spark plug 28 at a desired ignition timing. By applying this high voltage, a spark discharge is generated between the counter electrodes of each spark plug 28, and the air-fuel mixture introduced into the combustion chamber 16 is ignited and burned by the generated spark discharge. The engine 10 is a 4-stroke engine. That is, in the engine 10, one combustion cycle by four strokes of intake, compression, combustion, and exhaust is sequentially executed at a “720 ° CA” cycle.

  An in-cylinder pressure sensor 29 that measures a pressure (in-cylinder pressure) at a detection unit (a tip portion of a probe inserted into the combustion chamber) provided in the combustion chamber 16 is also attached to the cylinder head 15. In the engine 10, such an in-cylinder pressure sensor is also provided for each cylinder. The pressure in each cylinder (strictly, in the combustion chamber) is detected through these in-cylinder pressure sensors.

  In such a system, the ECU 40 is the part that mainly controls the engine as an electronic control unit. In addition to the sensor output (detection signal), detection signals from various sensors such as an accelerator sensor 42 for detecting the amount of accelerator operation (accelerator opening) by the driver (driver) are sequentially input to the ECU 40. . The ECU 40 grasps the operating state of the engine 10 and the user's request based on the detection signals of the various sensors, and operates the various actuators such as the injector 27 and the spark plug 28 in accordance therewith, thereby changing the situation from time to time. Various controls relating to the engine 10 are performed in an optimal manner according to the above.

  More specifically, the ECU 40 includes a known microcomputer (not shown). The microcomputer basically includes a CPU (basic processing device) for performing various calculations, a RAM (Random Access Memory) as a main memory for temporarily storing data and calculation results during the calculation, ROM (read-only storage device) as a program memory, EEPROM (electrically rewritable non-volatile memory) as a data storage memory, backup RAM (RAM powered by a backup power source such as an in-vehicle battery), and Consists of various arithmetic devices such as A / D converters and clock generation circuits, input / output ports for inputting / outputting signals to / from the outside, storage devices, signal processing devices, communication devices, etc. Has been. Furthermore, in this embodiment, by providing a high-speed digital processing processor (DSP) separately from the CPU, the processing speed of signal processing (particularly signal processing related to the output of the in-cylinder pressure sensor) performed on control can be improved. I have to. The ROM stores various programs and control maps related to engine control, and the data storage memory (for example, EEPROM) stores various control data including engine 10 design data in advance. Has been.

  Also in the present embodiment, similar to the device described in Patent Document 1 described above, the degree of heavyness (one of the fuel properties) of the fuel used is detected at the time of starting the engine, and the detected degree of heavyness of the fuel is detected. The fuel injection amount is variably controlled. However, in the engine control apparatus (ECU 40) of the present embodiment, in such fuel injection control, by performing (appropriate) injection control according to the in-cylinder pressure, combustion deterioration due to fuel properties is reduced and better. To achieve a good combustion state. Hereinafter, an aspect of such fuel injection control will be described in detail with reference to FIGS. The values of various parameters used in the processes of FIGS. 2, 5, and 6 are stored as needed in a storage device such as a RAM, EEPROM, or backup RAM mounted on the ECU 40, and updated as necessary. The And a series of processing of these each figure is fundamentally performed based on the program memorize | stored in ROM by ECU40.

  First, processing related to detection of fuel properties will be described with reference to FIG. The process of FIG. 2 is started when the engine 10 is started. Specifically, the engine 10 is started based on an on / off operation of an ignition switch. The ignition switch serves as an ignition switch and a start switch, and is turned on / off by a driver's key operation. In other words, when the driver inserts the ignition key into the key cylinder and turns it, the steering lock is released at the first stage, accessories such as radios at the second stage, current flows to the ignition device at the third stage, and the other stage When turned, the starter motor (not shown) rotates (cranks) the crankshaft (the output shaft of the engine 10) and starts the engine 10. The processing of FIG. 2 is started for each cylinder of the engine 10 triggered by cranking by the starter motor, and thereafter sequentially executed at predetermined crank angles or at predetermined time intervals until the fuel property detection end flag is turned ON. Is done.

  As shown in FIG. 2, in this series of processing, first, in step S11, the in-cylinder pressure at that time, that is, the pressure in the cylinder 12 (strictly in the combustion chamber 16) is measured by the in-cylinder pressure sensor 29. To do. Then, the measured data (actually measured value) is used for the above-mentioned water temperature corresponding to, for example, the engine operating condition (elapsed time from cranking or accelerator operation amount) and the engine operating state (engine speed, engine load, or cylinder temperature). The temperature is stored in association with the cooling water temperature or the like by the sensor 11b. In this case, in-cylinder pressure measurement data is stored in a nonvolatile manner in, for example, an EEPROM or a backup ROM so that it can be used for a long period of time. The data stored there remains without being erased. The process in step S11 is performed until a predetermined determination period (in this embodiment, for example, a fixed value of 1 or 2 combustion cycle periods, but a variable value is acceptable) elapses from cranking, that is, in the subsequent step S12. The process is repeated until it is determined that the process is completed.

  If it is determined in step S12 that the determination period has ended, it is determined that a predetermined determination period has elapsed from cranking, and the process proceeds to step S13. In step S13, based on the in-cylinder pressure data sequentially acquired (stored) during the determination period, a predetermined combustion parameter (a parameter indicating the combustion state), and thus a deviation from the reference value (normal value) of the parameter ( The combustion parameter deviation Y) is calculated. Here, as the combustion parameter, for example, one or a combination of a combustion end timing, a combustion period, a combustion center of gravity, and a peak timing of the heat generation rate can be used. Specifically, the combustion center of gravity is, for example, as shown in FIG. 3, when the misfire is the degree of combustion “0%” and the complete combustion is the degree of combustion “100%”, and the heat generation rate P10 of the degree of combustion “50%”. It is equivalent to. Further, the heat generation rate peak timing corresponds to the timing of the heat generation rate peak P12, that is, TDC (top dead center), for example, if the characteristic is indicated by the solid line L1 in FIG. The characteristics shown correspond to the timing t1 of the heat release rate peak P22. That is, for example, when the characteristic at the normal time is the characteristic indicated by the solid line L1, if the characteristic indicated by the broken line L2 is obtained, the difference “t1−TDC” is a time difference between the two. It will be calculated as Y.

  In the subsequent step S14 (FIG. 2), it is determined whether or not the combustion parameter deviation Y calculated in step S13 is within an allowable range. Specifically, the combustion parameter deviation Y is a predetermined threshold value B1 (here, a fixed value, but a variable value). However, it is determined whether it is larger. When there are a plurality of target combustion parameters, a plurality of threshold values B1 are prepared correspondingly. If it is determined in step S14 that the combustion parameter deviation Y is larger than the threshold value B1, it is determined that the fuel used is heavy fuel, and in step S141, the heavy fuel flag F (initial value = reset) is set. Set to ON. On the other hand, if it is determined in step S14 that the combustion parameter deviation Y is not larger than the threshold value B1 (below the threshold value B1), it is determined that the fuel used is not heavy fuel, and in step S142, the heavy fuel is used. Set flag F to OFF.

  In any of the cases where the degree of heavy or light fuel used is detected in these steps S141 and S142, in the next step S15, the fuel property detection end flag (initial value = OFF) is turned ON. Then, when this fuel property detection end flag is turned ON, the series of processes in FIG. 2 ends.

  Next, referring to FIG. 5, the fuel increase correction process that is started when the heavy fuel flag F is turned on in step S141 of FIG. 2 will be described. Note that the processing in FIG. 5 is sequentially executed at predetermined crank angles or at predetermined time intervals until the heavy fuel flag F is not turned on (turned off or reset).

  As shown in FIG. 5, in this series of processing, first in step S21, the combustion parameter deviation Y (calculated in step S13 in FIG. 2 or step S24 described later) and a predetermined engine operating state (for example, engine load and Based on the cylinder temperature, an initial value K1 (initial increase value) of the fuel increase correction coefficient is calculated. In detail, for example, a predetermined map in which an appropriate value (optimum value) of the initial value K1 is written for each combustion parameter deviation Y, every engine load, and every engine cooling water temperature by an experiment or the like is stored in advance (for example, stored in a ROM or a mathematical expression). ) To obtain.

  In the subsequent step S22, the reduction degree K2 of the fuel increase correction coefficient is calculated this time based on the combustion parameter deviation Y and the predetermined engine operating state (for example, engine load and cylinder temperature). Also in this step S22, a predetermined map (for example, stored in a ROM or the like, may be a mathematical expression) is used.

  In the subsequent step S23, it is determined whether or not the elapsed time from the start of fuel increase correction (timing when the heavy fuel flag F is turned on) is less than a predetermined threshold B2 (here, a fixed value, but a variable value is also acceptable). The initial value K1 (calculated in step S21) is repeatedly (continuously) set in the fuel increase correction coefficient K in the following step S231 until the predetermined threshold B2 has elapsed from the start of the fuel increase correction. become.

  In the present embodiment, at least at the time of engine start, the basic injection amount Q1 (for example, a map conforming value determined for each engine operating state) is multiplied by the fuel increase correction coefficient K to thereby obtain a target value for the fuel injection amount ( = Q1 × K) is determined (calculated). Then, the fuel injection amount is controlled to the target value by variably controlling the drive amount (for example, valve opening time) of the injector 27 according to the target value of the fuel injection amount. Note that this correction processing (processing for calculating the fuel injection amount) is performed according to a generally known processing procedure, and therefore illustration (flow chart) is omitted. Incidentally, here, since it is assumed that the fuel injection amount is corrected to be increased, K is set to a value larger than “1 time”.

  In subsequent step S24, processing similar to steps S11 and S13 of FIG. 2, that is, in-cylinder pressure measurement, data storage, and combustion parameter deviation Y are calculated. In the subsequent step S25, it is determined whether or not the combustion parameter deviation Y calculated in step S24 is within an allowable range. Specifically, the combustion parameter deviation Y is based on a predetermined threshold B3 (here, a fixed value, but a variable value is also acceptable). It is judged whether it is also large. In this embodiment, the threshold value B3 is set to a value smaller than the threshold value B1 used in the determination of the degree of heavy / light fuel in the previous step S14 in order to compensate for the combustion deviation more reliably.

  Then, while it is determined in step S25 that the combustion parameter deviation Y is larger than the threshold value B3 (Y> B3), the process proceeds to step S26, and abnormality (failure) determination is performed in step S26. Specifically, the integrated value (integrated air amount) of the fresh air amount measured by the air flow meter 25 is set to a predetermined threshold B4 (here, a fixed value, for example, a value corresponding to a predetermined period before warming up. It is determined whether it is less than a variable value. If the combustion parameter deviation Y is not less than or equal to the threshold value B3 even if the integrated air amount is equal to or greater than the threshold value B4, the process proceeds to the subsequent step S261 as being abnormal (failed), and the heavy fuel is obtained. The flag F is reset (to make it a neutral state that is neither ON nor OFF), and predetermined fail-safe processing (for example, processing for storing a diagnostic code in an EEPROM or the like, processing for lighting a predetermined warning lamp, etc.) is executed. . Note that when the heavy fuel flag F is reset, the series of processes in FIG. 5 ends with the reset. On the other hand, if it is determined in step S26 that the integrated air amount is less than the threshold value B4 (integrated air amount <threshold value B4), it is determined that the operation is normal, and the processes in steps S21 to S25 are repeated. However, if it is determined in the previous step S23 that the elapsed time from the start of the fuel increase correction is not less than the threshold B2 (is greater than or equal to the threshold B2), the process proceeds to step S232, and the fuel increase correction coefficient K is set to the initial value K1. From now on, the amount of weight loss will be updated by decreasing K2. Specifically, in step S232, a value obtained by subtracting the degree of decrease K2 from the previous value (K (previous value)) of the fuel increase correction coefficient K is used as the current value (K (current value)) of the fuel increase correction coefficient K. And

  Thus, according to the series of processes in FIG. 5, the fuel increase correction coefficient K is updated as described above. If it is determined in the previous step S25 that the combustion parameter deviation Y is not greater than the threshold value B3 (below the threshold value B3), the heavy fuel flag F is turned off in the following step S251. When the fuel flag F is turned off, the series of processes in FIG. 5 is terminated.

  Next, referring to FIG. 6, the fuel injection control that is started when the heavy fuel flag F is turned off in step S142 of FIG. 2 or step S251 of FIG. 5 will be described. 6 is sequentially executed at predetermined crank angles or at predetermined time intervals until the heavy fuel flag F is not turned off (turned on or reset).

  As shown in FIG. 6, in this series of processes, the fuel increase correction coefficient K is set to “1” in the first step S31. However, at this time, the value of the fuel increase correction coefficient K is gradually changed based on the previous value (gradual change process). Then, in the following step S32, the integrated air amount is not less than a predetermined threshold B5 (here, a fixed value, for example, a value corresponding to a predetermined period before warm-up is set. However, a variable value is also acceptable) (is a threshold B5 or more). In step S31, “1 time” is repeatedly (continuously) set in the fuel increase correction coefficient K until it is determined. That is, during this time, the fuel injection amount is not corrected by the fuel increase correction coefficient K.

  If it is determined in step S32 that the integrated air amount is not less than the threshold value B5 (is greater than or equal to the threshold value B5), the heavy fuel flag F is reset and a correction end flag (initial value = OFF) in subsequent step S321. Set to ON. Then, when the correction end flag is turned ON, the series of processes in FIG. 6 ends.

  Next, an aspect of fuel injection control by the ECU 40 (engine control device) will be briefly described with reference to FIG. 7A is a timing chart showing the transition of the heavy fuel flag F, and FIG. 7B is a timing chart showing the transition of the fuel injection amount. For comparison, the injection control characteristic by the apparatus illustrated in FIG. 8 is shown as a broken line L20 in FIG.

  As shown in FIG. 7, when cranking is performed by the starter motor at timing t11, the determination period (step S12) is entered. As described above, the cylinder pressure data at that time is sequentially stored (accumulated) during this determination period. Then, by sequentially determining whether or not this period has ended in step S12 of FIG. 2, the period end timing t12 is detected, and at this period end timing t12, the degree of heavy / light fuel used is detected. .

  Here, that is, when it is determined in step S14 of FIG. 2 that the fuel used is heavy fuel, in step S141, as shown by the solid line L11a in FIG. The flag F is turned ON, and fuel increase correction is performed as indicated by the solid line L11b in FIG. 7B. Specifically, the fuel injection amount maintained at the basic injection amount Q1 is the injection amount Q2 (= Q1 ×) based on the initial value K1 of the fuel increase correction coefficient (calculated in step S21 in FIG. 5) at the period end timing t12. Increased to K1). When it is determined in step S23 of FIG. 5 that the time corresponding to the threshold value B2 has elapsed, at time t13, the amount of decrease by a predetermined injection amount determined by the amount of decrease K2 (calculated in step S22 of FIG. 5) is decreased. Be started. In the present embodiment, such fuel increase correction is executed in the start injection control period t12 to t14 (FIG. 7). Then, by executing such fuel increase correction, the decrease in the engine rotation speed (see FIG. 8) at the time of starting the engine is recovered (increased) to a predetermined level.

  Thereafter, when the combustion parameter deviation Y becomes equal to or less than the threshold value B3 (determined in step S25 in FIG. 5), it is assumed that the decrease in the engine speed has sufficiently recovered, as shown by the solid line L11a in FIG. At the timing t14, the heavy fuel flag F is turned off (step S251 in FIG. 5). As a result, in step S31 of FIG. 6, the fuel increase correction coefficient K is gradually reduced to "1" over time from timing t14 to timing t15.

  Such fuel injection control is executed in the starting period of the engine 10 determined by the threshold value B5 (step S32 in FIG. 5), that is, the periods t11 to t20. Therefore, at time t20, the heavy fuel flag F is reset by the process of step S321 in FIG.

  On the other hand, if it is determined in step S14 of FIG. 2 that the fuel used is not a heavy fuel, the process of step S141 is performed at timing t12 as shown by a two-dot chain line L12a in FIG. 7A. As a result, the heavy fuel flag F is turned OFF and the processing of FIG. 6 is executed. For this reason, as shown by a two-dot chain line L12b in FIG. 7B, the fuel increase correction is not performed.

  According to the engine control device and the fuel property detection device according to the present embodiment described above, the following excellent effects can be obtained.

  (1) As a control device for the engine 10 (engine control ECU 40), from a predetermined start timing t12 at the time of engine start to an end timing t14 at which a predetermined condition (condition relating to the magnitude of combustion deviation in this embodiment) is established. A program for controlling the fuel injection amount to a target value determined based on the pressure in the cylinder (cylinder pressure) when performing fuel injection in the start injection control period t12 to t14 (FIG. 7) (fuel injection control means, 5). Specifically, during the starting injection control period t12 to t14, the combustion state is monitored (monitored) (step S24 in FIG. 5), and the fuel amount at each time is controlled to an appropriate value. As a result, the deterioration of combustion at the time of starting the engine due to the fuel properties and the like is reduced, and as a result, the emission is improved.

  (2) A program (combustion parameter acquisition means, step S24 in FIG. 5) for converting the pressure in the cylinder (in-cylinder pressure) into another parameter (combustion parameter) indicating the combustion state is provided, and the step in FIG. In S21 and S22, the fuel injection amount is controlled to the target value determined based on the combustion parameter as the conversion value acquired in step S24 of FIG. Specifically, an example is shown in which at least one of the combustion end timing, the combustion period, the combustion center of gravity (see FIG. 3), and the peak timing of the heat generation rate (see FIG. 4) is used as the combustion parameter. These combustion parameters are generally used as parameters indicating the combustion state, and are particularly important. Therefore, by adopting such a configuration, a good combustion state particularly required for practical use can be obtained.

  (3) In step S11 of FIG. 2 and step S24 of FIG. 5, the engine operating conditions (elapsed time from cranking or accelerator operation amount, etc.) and the engine operating state (engine speed, engine load, cylinder temperature, etc.) at that time ), The cylinder pressure is successively stored in a nonvolatile manner. With such a configuration, it becomes easy to obtain the combustion parameters with high accuracy based on the in-cylinder pressure data accumulated (sequentially stored).

  (4) A program (correction coefficient acquisition means, steps S21, S22, S231, S232 in FIG. 5) for obtaining a correction coefficient K for the basic target value Q1 of the fuel injection amount based on the pressure in the cylinder (cylinder pressure). It was set as the structure provided. The fuel injection amount is controlled to the target value (= Q1 × K) determined based on the correction coefficient K. By doing so, it becomes possible to perform fuel injection control that accurately compensates for the combustion deviation (combustion parameter deviation Y), and thus it becomes possible to realize a good combustion state more easily and accurately. .

  (5) The correction coefficient K related to the fuel injection amount is corrected to increase the fuel injection amount. By adopting such a configuration, it is possible to recover (increase) the above-described decrease in the engine rotation speed (see FIG. 8) at the time of starting the engine more accurately to a predetermined level.

  (6) In the process of FIG. 5, the start injection control period in a manner in which the initial increase value (basic injection amount Q1) is decreased by a predetermined injection amount determined by the decrease degree K2 (calculated in step S22 of FIG. 5). The injection control in was performed. Then, the initial increase value (K1), the decrease end timing (end at “K = 1”), and the decrease degree (K2) are determined for the correction coefficient K related to the target value of the fuel injection amount. In this way, the fuel increase correction can be easily and accurately performed.

  (7) A program that determines whether or not to perform fuel increase correction based on the pressure value in the cylinder in the determination periods t11 to t12 (FIG. 7) provided before the start injection control period t12 to t14 (FIG. 7). (Control execution means, FIG. 2). With such a configuration, the above configuration can be realized with simple control.

  (8) Further, the fuel property detection device includes a program (fuel property detection means, FIG. 2) that detects the fuel property based on the pressure in the cylinder (cylinder pressure). According to such an apparatus, it becomes possible to easily measure the fuel property (height and lightness in this embodiment) with relatively high accuracy.

  The above embodiment may be modified as follows.

  In the above embodiment, the gradual change process is performed in step S31 of FIG. 6, but this gradual change process is not essential, and the fuel increase correction coefficient K may be reduced to “1” at a stretch. Good.

  In the above embodiment, the determination periods t11 to t12 (FIG. 7) are provided before the start injection control periods t12 to t14 (FIG. 7), and whether or not the fuel increase correction is performed is determined only by this determination period. . However, the present invention is not limited to such a configuration. For example, the execution determination of the fuel increase correction may be performed all over the start period t11 to t20.

  In the above embodiment, the fuel property of the fuel used and the target value of the fuel injection amount are obtained for each cylinder (for all four cylinders) based on the in-cylinder pressure when the engine is started. However, the present invention is not limited to such a configuration, and an average value per cylinder of the multi-cylinder engine (4 in the above embodiment) regarding the pressure in the cylinder (in-cylinder pressure) or another parameter (for example, a combustion parameter) using the pressure. (Cylinder average value) is calculated, and a program (average value calculation means) is provided. Based on the calculated average value, for example, the fuel property of the fuel used is detected, or the target value of the fuel injection amount is determined. It may be configured to do. With such a configuration, errors due to variations between cylinders are reduced, and it becomes possible to more accurately detect the fuel properties of the fuel used. As a result, as a target value of the fuel injection amount for realizing a good combustion state Even you will be able to get more accurate values.

  In the above embodiment, the fuel injection amount is variably controlled during the start injection control period t12 to t14 (FIG. 7). However, the present invention is not limited to this. For example, the correction of the fuel injection amount may be performed in a binary manner as in the control shown in FIG. In this case, a program (correction execution period variable means) is provided that makes the length of the correction execution period (periods t51 to t52 in FIG. 8) variable based on the pressure in the cylinder (cylinder pressure). Is effective. With such a configuration, it is possible to set the length of the correction execution period to an appropriate length based on the in-cylinder pressure, and as a result, good emission characteristics can be constantly obtained.

  In the above embodiment, the fuel injection amount is variably controlled based on the pressure in the cylinder (cylinder pressure), so that the engine output (output torque) is controlled to a desired value. did. However, instead of the fuel injection amount, other parameters relating to the magnitude of the output torque can be used. In this case, the program for controlling the parameter relating to the magnitude of the output torque corresponds to “torque control means”.

  Specifically, for example, ignition timing, charging efficiency (for example, supercharging amount, fresh air amount, intake air temperature, etc. in the case of an engine equipped with a supercharging device), EGR (exhaust gas recirculation) amount (engine equipped with an EGR device) ), Intake / exhaust valve timing / valve lift amount (in the case of an engine having a variable valve mechanism), driving amount of an ignition auxiliary device (in an engine having an ignition auxiliary device such as a glow plug), Any arbitrary parameters (including combinations) can be used instead of the fuel injection amount. Even with such a configuration, by controlling the engine output based on the in-cylinder pressure, it is possible to recover (increase) the above-described decrease in engine rotation speed (see FIG. 8) at the time of engine start to a predetermined level.

  -You may comprise so that the fuel property (heavy / lightness degree) detected by the process of the said FIG. 2 may be used for uses other than engine control.

  The type of engine to be controlled (including, for example, an in-cylinder gasoline engine or a compression ignition type diesel engine) and the system configuration can be changed as appropriate according to the application. For example, in the above embodiment, the in-cylinder pressure sensor is provided for each cylinder, but this sensor is provided only for some cylinders (for example, one cylinder), and the estimated values based on the sensor output for other cylinders. May be used. Further, as in the apparatus described in Patent Document 1, a heavy / light sensor may be provided to detect the heavy / light degree of the used fuel with higher accuracy.

  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.

1 is a configuration diagram showing an outline of an engine control system to which an engine control device and a fuel property detection device according to an embodiment of the invention are applied. The flowchart which shows the process sequence of the process which concerns on detection of a fuel property. The graph which shows an example of a combustion parameter. The graph which shows another example of a combustion parameter. The flowchart which shows the process sequence of a fuel increase correction process. The flowchart which shows the process sequence of fuel-injection control when not performing increase correction. The timing chart which shows the one aspect | mode of the fuel-injection control by the engine control apparatus of this embodiment. The timing chart which shows the operation | movement aspect about an example of the conventional engine control apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 12 ... Cylinder (cylinder), 16 ... Combustion chamber, 26 ... Throttle valve, 27 ... Injector, 28 ... Spark plug, 29 ... In-cylinder pressure sensor, 40 ... ECU (electronic control unit).

Claims (12)

An engine control device that rotates the output shaft by generating torque on the output shaft of the engine through combustion of fuel in a cylinder of the target engine,
It is determined based on the pressure in the cylinder when injecting and supplying the fuel to be used in the start-up injection control period from the predetermined start timing at the start of the engine to the end timing at which the predetermined condition is satisfied. An engine control apparatus comprising fuel injection control means for controlling a fuel injection amount to a target value. When the engine is a multi-cylinder engine that burns the fuel in each of a plurality of cylinders, the pressure in the cylinder or another parameter using the pressure is determined per cylinder of the multi-cylinder engine. An average value calculating means for calculating the average value of
The engine control apparatus according to claim 1, wherein the fuel injection control means controls the fuel injection amount to a target value determined based on the average value calculated by the average value calculation means. Combustion parameter acquisition means for converting the pressure in the cylinder into another parameter indicating a combustion state,
The engine control according to claim 1 or 2, wherein the fuel injection control means controls the fuel injection amount to a target value determined based on a combustion parameter as a conversion value acquired by the combustion parameter acquisition means. apparatus.   The engine control device according to claim 3, wherein the combustion parameter is at least one of a combustion end timing, a combustion period, a combustion gravity center, and a peak timing of a heat generation rate. Correction coefficient obtaining means for obtaining a correction coefficient for the basic target value of the fuel injection amount based on the pressure in the cylinder;
The engine according to any one of claims 1 to 4, wherein the fuel injection control means controls a fuel injection amount to a target value determined based on a correction coefficient acquired by the correction coefficient acquisition means. Control device.   The engine control apparatus according to claim 5, wherein the correction coefficient related to the target value of the fuel injection amount corrects the fuel injection amount to be increased. The fuel injection control means performs injection control in the start injection control period in a manner of decreasing the initial increase value by a predetermined amount of decrease.
The engine control apparatus according to claim 6, wherein the correction coefficient related to the target value of the fuel injection amount determines at least one of an initial increase value, a decrease end timing, and a decrease degree.   The engine control device according to any one of claims 5 to 7, further comprising a correction execution period varying unit that varies a length of a correction execution period with respect to a basic target value of the fuel injection amount based on a pressure in the cylinder. .   Control execution means for determining whether or not fuel injection control based on the cylinder pressure by the fuel injection control means is executed based on a pressure value in the cylinder in a determination period provided before the start injection control period. The engine control apparatus as described in any one of Claims 1-8. An engine control device that rotates the output shaft by generating torque on the output shaft of the engine through combustion of fuel in a cylinder of the target engine,
It is determined based on the pressure in the cylinder when injecting and supplying the fuel to be used in the start-up injection control period from the predetermined start timing at the start of the engine to the end timing at which the predetermined condition is satisfied. An engine control device comprising torque control means for controlling a parameter related to the magnitude of the generated torque to a target value.   The engine control device according to claim 10, wherein the engine is a spark ignition engine that performs ignition for fuel ignition by a predetermined ignition method, and the parameter related to the magnitude of the torque is an ignition timing.   A fuel property detecting means for detecting a fuel property based on the pressure in the cylinder is provided for an engine that rotates the output shaft by generating torque on the output shaft through combustion of fuel in the cylinder. Fuel property detection device.

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