JP4416122B2 - Fuel injection device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection device provided in a fuel supply system of an internal combustion engine represented by a diesel engine. In particular, the present invention performs post injection (expansion) performed to regenerate a diesel particulate filter (hereinafter referred to as DPF) that collects particulate matter (hereinafter referred to as PM) in exhaust gas. The present invention relates to measures for optimizing the execution timing of fuel injection performed in a stroke or an exhaust stroke.

  In recent years, internal combustion engines mounted on automobiles and the like have been required to improve exhaust emissions. In particular, diesel engines remove PM such as soot contained in exhaust gas in addition to CO, HC and NOx. It is demanded. For this reason, in a diesel engine, DPF comprised with the porous material is arrange | positioned in an exhaust passage, and PM in exhaust gas is collected by this DPF.

  Since this DPF is composed of a porous material as described above, if the amount of PM trapped increases excessively, the flow resistance in the DPF increases, the back pressure of the engine increases, and the output decreases. It will be. For this reason, it is necessary to appropriately remove the PM trapped in the DPF, regenerate the DPF, and recover the PM trapping ability.

  In order to make it possible to regenerate the DPF while the engine is running, an apparatus is known in which an oxidation catalyst such as platinum is provided in the DPF and the oxidation action of the oxidation catalyst is utilized. For example, in addition to the “main injection” for injecting fuel from the injector at the end of the compression stroke of the engine, “post injection” for injecting fuel from the injector in the expansion stroke or the exhaust stroke is performed, and the fuel is supplied to the DPF. The heat of oxidation reaction is obtained with an oxidation catalyst, and the PM collected in the DPF is burned and removed using the heat.

Until now, as the timing for executing the post injection, as disclosed in the following Patent Document 1 and Patent Document 2, the pressure difference between the upstream side and the downstream side of the DPF is detected by a sensor, and this pressure difference is detected. Is increased, that is, when it is detected that the DPF is clogged, post injection is performed. In addition, when a temperature sensor is attached to the DPF and the detected value continues to be below a predetermined value (for example, operation at a low speed / light load continues for a predetermined time, and PM does not undergo combustion removal in the DPF) ) Was running post injection.
JP 2003-161138 A JP 2004-11446 A

  However, in the past, a special sensor for detecting the state of the DPF such as the pressure difference sensor and the temperature sensor was required to determine the post injection execution timing, which caused an increase in the manufacturing cost of the engine. .

  In addition, the post-injection is always performed so that the sensor is not necessary, but this greatly increases the fuel consumption.

  The present invention has been made in view of such points, and the object of the present invention is to avoid an increase in fuel consumption and without requiring a special sensor for detecting the state of the DPF. Another object of the present invention is to provide a fuel injection device for an internal combustion engine capable of performing post injection at an appropriate timing.

-Summary of invention-
The solution of the present invention taken to achieve the above object is to obtain the PM trap amount of the DPF based on the operating state of the engine (for example, the fuel injection amount in the main injection of the injector, the engine speed, etc.). Assuming that the amount of PM collected becomes excessive, post-injection from the injector is started.

-Solution-
Specifically, the present invention is provided in an internal combustion engine having a particulate filter that collects particulate matter in exhaust gas in the middle of an exhaust passage, and performs the above-described particulate filter by performing post injection from a fuel injection means. And a fuel injection device that regenerates the particulate filter by burning and removing the collected particulate matter. This fuel injection device is provided with operating state recognition means, accumulated numerical value output means, integration means, determination means, post injection start means, and post injection decrease amount output means. The operating state recognition means recognizes the operating state of the internal combustion engine. The accumulated numerical value output means receives the output of the operating state recognition means and digitizes and outputs the particulate matter increase amount and the particulate matter decrease amount in the particulate filter according to the operating state of the internal combustion engine. The accumulating means accumulates the received numerical values every time the output from the accumulated numerical value outputting means is received. The determining means receives the output of the integrating means and determines whether or not the integrated value has reached a predetermined post-injection start value. The post injection start means receives the output of the determination means, and starts the post injection of the fuel injection means when the integrated value reaches a predetermined post injection start value. The post-injection decrease amount output means quantifies and outputs the particulate matter decrease amount due to post injection.

Based on this specific matter, the operating state recognition means recognizes the operating state of the internal combustion engine such as the fuel injection amount and engine speed in the main injection, and performs PM combustion removal in the DPF, for example, at low speed and light load. Recognize that the situation is incongruent. Then, the accumulated numerical value output means, in the situation where PM is not removed by combustion in the DPF according to the operating state of the internal combustion engine (the situation where the DPF cannot be regenerated), the particles corresponding to the operating state A situation where the amount of increase in particulate matter is converted into a positive value and output, and PM is burned and removed by the DPF (for example, a situation where the exhaust temperature rises and the DPF can be regenerated, such as at high speed and high load) If it is, the particulate matter reduction amount corresponding to the operation state is converted into a negative value and output. For example, a map for obtaining these values according to the fuel injection amount in the main injection and the engine speed is stored in advance, and the particulate matter increase amount and particulate matter decrease amount are digitized and output according to this map. The accumulating means sequentially accumulates the numerical values related to the increase in particulate matter and the decrease in particulate matter (addition of a negative number, that is, subtraction when a numerical value related to the decrease in particulate matter is output). The amount of PM trapped in the DPF is estimated from the integrated value. When it is determined by the determining means that the integrated value has reached a preset post-injection start value, the post-injection of the fuel injecting means is started, and the collected PM is burned and removed. Will be played. Thus, in this solution, since the amount of PM trapped is estimated based on the operating state of the internal combustion engine, a special sensor (pressure difference sensor or temperature sensor) for detecting the state of the DPF is not required. In addition, post injection can be executed at an appropriate timing. In addition, since it is not necessary to always perform post injection, there is no significant increase in fuel consumption.

Specific examples of the operation state recognition operation of the internal combustion engine by the operation state recognition unit and the output value setting operation of the accumulated numerical value output unit include the following. In other words, the operation state recognition means recognizes the operation state of the internal combustion engine by detecting the fuel injection amount in the main injection of the fuel injection means and the engine speed of the internal combustion engine. The accumulated numerical value output means outputs either the positive value or the negative value at a predetermined fuel injection amount at the same engine speed, and the predetermined fuel injection amount at the boundary is the engine rotation speed. The positive value is outputted as a larger value as the engine speed is lower, and the negative value is outputted as a smaller value as the engine speed is higher . It is configured.

  Specifically, there are the following two types of timing for the operation state recognition operation of the internal combustion engine by the operation state recognition unit and the output operation of the accumulated numerical value output unit.

  First, as a first type, the operating state recognition unit recognizes the operating state of the internal combustion engine at predetermined time intervals (for example, every several msec) and outputs the recognition information to the accumulated numerical value output unit. Further, every time the accumulated numerical value output means receives the recognition information from the operating state recognition means, the particulate matter increase amount and the particulate matter decrease amount in the particulate filter are numerically indicated according to the operation state of the internal combustion engine. Output.

  As a second type, the operation state recognition means recognizes the operation state of the internal combustion engine for each cycle of each cylinder of the internal combustion engine and outputs the recognition information to the accumulated numerical value output means. Further, every time the accumulated numerical value output means receives the recognition information from the operating state recognition means, the particulate matter increase amount and the particulate matter decrease amount in the particulate filter are numerically indicated according to the operation state of the internal combustion engine. Output.

  Further, the following two types are listed as the configuration for stopping the post injection of the fuel injection means.

  First, as a first type, even during execution of post-injection of the fuel injection means, the operation state recognition operation of the internal combustion engine by the operation state recognition means, the particulate matter increase amount and the particulate matter decrease amount by the accumulated numerical value output means. The output operation of the digitized information and the numerical integration operation by the integration unit are continuously executed, and the particulate matter reduction amount by the post injection, that is, the output value of the post injection reduction amount output unit is also integrated. And a post-injection stop means for stopping the post-injection of the fuel injection means when the determination means determines that the integrated value of the integration means falls below a predetermined post-injection stop value during the post injection of the fuel injection means. I am letting.

  As a second type, the operation state recognition operation of the internal combustion engine by the operation state recognition unit and the particulate matter increase amount and the particulate matter decrease amount by the accumulated numerical value output unit are quantified even during the post injection of the fuel injection unit. The output operation of the information and the numerical integration operation by the integration means are continuously executed. During the post injection of the fuel injection means, the elapsed time from the start time of the post injection has reached a preset post injection completion time, or the integrated value of the integrating means is a predetermined post injection stop value. A post-injection stop means is provided for stopping the post-injection of the fuel injection means when any of the conditions determined by the determination means as being lower than is satisfied.

  In the case where the post injection stopping means is provided, the integrated value of the integrating means is returned to the initial value (for example, “0”) when the post injection of the fuel injection means is stopped. In other words, when post-injection stops, it is assumed that PM in the DPF has been completely burned and removed, and it is assumed that there is almost no PM in the DPF, and the amount of PM trapped in the subsequent DPF is estimated. We will move on.

  Further, by setting different values for the post injection start value and the post injection stop value, a hysteresis is provided between the integrated value for determining the post injection start time and the integrated value for determining the post injection stop time. Thereby, it is possible to avoid hunting in which execution and non-execution of post-injection are alternately repeated in a short time.

  As described above, in the present invention, the post injection start timing is determined while estimating the PM collection amount of the DPF based on the operating state of the engine. Therefore, it is possible to regenerate the DPF by executing post injection at an appropriate timing without requiring a special sensor for detecting the state of the DPF such as a pressure difference sensor or a temperature sensor. As a result, the manufacturing cost of the engine can be reduced, and the post-injection does not need to be constantly performed, so that the fuel consumption is not significantly increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a case where the present invention is applied to a fuel injection device mounted on a four-cylinder industrial diesel engine will be described.

-Description of fuel injection system configuration-
First, the overall configuration of the fuel injection device applied to the engine according to the present embodiment will be described. FIG. 1 shows a pressure accumulation type fuel injection device provided in a four-cylinder marine diesel engine.

  This accumulator fuel injection device includes a plurality of fuel injection valves (hereinafter referred to as injectors) 1, 1,... Attached corresponding to each cylinder of a diesel engine (hereinafter simply referred to as an engine), and a relatively high pressure ( A common rail 2 for accumulating high-pressure fuel with a common rail internal pressure (for example, 100 MPa), and a high-pressure pump as a fuel pump that pressurizes fuel sucked from the fuel tank 4 via a low-pressure pump (feed pump) 6 and discharges the fuel into the common rail 2 , And a controller (ECU) 12 that electronically controls the high-pressure pump 8.

  The high-pressure pump 8 is a so-called plunger-type supply fuel supply pump that is driven by an engine, for example, and boosts the fuel to a high pressure determined based on an operating state or the like and supplies the fuel to the common rail 2 through the fuel supply pipe 9. For example, the high-pressure pump 8 is connected to a crankshaft of the engine via a gear so that power can be transmitted. As another configuration for transmitting the power, a pulley is provided on each of the drive shaft of the high-pressure pump 8 and the crankshaft of the engine, and a belt is placed on the pulley so that the power can be transmitted, or a sprocket is provided on each shaft. It is also possible to provide a power transmission by linking a chain to the sprocket.

  Each of the injectors 1, 1,... Is attached to the downstream end of a fuel pipe that communicates with the common rail 2. The fuel injection from the injector 1 is controlled, for example, by energizing and stopping energization (ON / OFF) of an electromagnetic valve for injection control (not shown) integrated in the injector. That is, the injector 1 injects the high-pressure fuel supplied from the common rail 2 toward the combustion chamber of the engine while the injection control electromagnetic valve is open.

  The controller 12 receives various engine information such as the engine speed and engine load, and provides the injection control solenoid valve with the optimal fuel injection timing and fuel injection amount determined from these signals. Output a control signal. At the same time, the controller 12 outputs a control signal to the high pressure pump 8 so that the fuel injection pressure becomes an optimum value according to the engine speed and the engine load. Further, a pressure sensor 13 for detecting the common rail internal pressure is attached to the common rail 2, and the high pressure pump is set so that the signal of the pressure sensor 13 becomes an optimum value set in advance according to the engine speed and the engine load. The amount of fuel discharged from 8 to the common rail 2 is controlled.

  The fuel supply operation to each injector 1 is performed from the common rail 2 through the branch pipe 3 constituting a part of the fuel flow path. That is, the fuel taken out from the fuel tank 4 through the filter 5 by the low-pressure pump 6 and pressurized to a predetermined suction pressure is sent to the high-pressure pump 8 through the fuel pipe 7. The fuel supplied to the high-pressure pump 8 is stored in the common rail 2 in a state where the pressure is increased to a predetermined pressure, and is supplied from the common rail 2 to the injectors 1, 1,. A plurality of injectors 1 are provided according to the type of engine (the number of cylinders, four cylinders in this embodiment), and the fuel supplied from the common rail 2 is optimally injected at the optimal injection timing under the control of the controller 12. A quantity is injected into the corresponding combustion chamber (main injection). Since the injection pressure of the fuel injected from the injector 1 is substantially equal to the pressure of the fuel stored in the common rail 2, the pressure in the common rail 2 is controlled to control the fuel injection pressure.

  Further, of the fuel supplied from the branch pipe 3 to the injector 1, the fuel that was not spent for injection into the combustion chamber and the excess fuel when the common rail internal pressure excessively rises are returned to the fuel tank 4 through the return pipe 11. .

  The controller 12, which is an electronic control unit, receives information on a cylinder number and a crank angle (not shown).

  The controller 12 includes a fuel injection amount control means for determining a fuel injection amount, and a target fuel injection condition (for example, a target fuel injection) determined in advance based on the engine operating state so that the engine output becomes an optimum output in accordance with the operating state. The fuel injection timing and the target common rail internal pressure are stored as functions (these are not shown), and the target fuel injection conditions (that is, the fuel by the injector 1) corresponding to the signals representing the current engine operating state detected by various sensors. The operation of the injector 1 and the fuel pressure in the common rail are controlled so that fuel injection (main injection) is performed under the conditions.

  FIG. 2 is a control block of the fuel injection amount control means stored in the controller 12. As shown in FIG. 2, the calculation of the fuel injection amount is performed by the command rotational speed calculation means 12A receiving the opening signal of the regulator operated by the user, and the command rotational speed calculation means 12A corresponds to the opening of the regulator. Command rotation speed "is calculated. Then, the injection amount calculation means 12B calculates the fuel injection amount so that the engine rotation speed becomes the command rotation speed. In the injector 1 of the engine (internal combustion engine) E, the fuel injection operation is performed with the fuel injection amount obtained by this calculation. In this state, the rotational speed calculation means 12C calculates the actual engine rotational speed, and this actual engine Comparing the rotational speed with the command rotational speed, the fuel injection amount is corrected (feedback control) so that the actual engine rotational speed matches the command rotational speed.

  In this way, the pressure accumulation type fuel injection device accumulates the discharged fuel pumped from the high pressure pump 8 in the common rail 2, and appropriate fuel injection timing (fuel injection timing) and fuel injection duration time according to the operating state of the engine E. And the injector 1 is driven to inject fuel. The common rail internal pressure is controlled by controlling the high pressure pump 8 according to the fuel injection from the injector 1 to pump the fuel and controlling the pumping amount so that the common rail internal pressure is maintained at the optimum injection pressure. Like to do.

-Configuration explanation of engine exhaust system-
Next, the configuration of the engine exhaust system according to this embodiment will be described. FIG. 3 is a schematic configuration diagram showing the engine body E1 and the exhaust system 15 thereof. As shown in FIG. 3, the exhaust system 15 includes an exhaust pipe 15a connected to an exhaust manifold E2 extending from the engine body E1, and a DPF 15b as a post-processing device is provided in the middle of the exhaust pipe 15a. It has been. The DPF 15b is configured such that exhaust gas discharged from each cylinder of the engine body E1 through the exhaust manifold E2 to the exhaust pipe 15a flows. The DPF 15b is, for example, one in which an oxidation catalyst such as platinum is supported on a porous material such as ceramic through which exhaust gas can flow. More specifically, the DPF 15b is configured by holding a porous material carrying a catalyst in a metal catalyst case (catalyst container) constituting an exhaust passage. The DPF 15b may be a ceramic honeycomb filter, a foam filter, a fiber filter, or the like in addition to a wall flow type in which a catalyst is coated on the surface of a porous ceramic as described above. A metal filter may also be used.

  The DPF 15b configured in this manner collects PM, which is fine particles discharged from the engine body E1 (main components are carbon suit, unburned fuel, and high-molecular hydrocarbons (HC) such as oil). The exhaust gas can be purified.

-Configuration for performing post injection and post injection operation-
When the amount of collected PM increases excessively, the DPF 15b may increase the flow resistance in the DPF 15b and cause a decrease in engine output. For this reason, apart from “main injection” in which fuel is injected from the injector 1 at the end of the compression stroke of the engine E, “post injection” in which fuel is injected from the injector 1 in the expansion stroke or exhaust stroke is executed. As a result, the fuel is supplied to the DPF 15b, the oxidation reaction heat is obtained by the oxidation catalyst, the PM trapped in the DPF 15b is burned and removed using the heat, and the DPF 15b is regenerated to improve the PM trapping ability. It tries to recover.

  The feature of this embodiment is that optimization of the execution timing of the post injection for removing the PM by combustion is achieved. Hereinafter, a configuration for setting the execution timing of the post injection will be described.

  As shown in FIGS. 1 and 4, the controller 12 is a means for setting the execution timing of the post injection, as shown in FIGS. 1 and 4, an operating state recognition unit 12D, an accumulated numerical value output unit 12E, an integration unit 12F, a determination unit 12G, a post unit An injection start unit 12H, a post injection stop unit 12I, and a post injection decrease amount output unit 12J are provided.

  The operating state recognition means 12D recognizes the operating state of the engine E. Specifically, the fuel injection amount and the engine speed in the main injection of the injector 1 are detected to recognize the operating state of the engine E. For example, the output from the injection amount calculation means 12B is received to detect the fuel injection amount in the main injection, and the output from the engine speed sensor (not shown) is detected to detect the engine speed.

  The operation state recognition unit 12D recognizes the operation state of the engine E. The recognition operation is executed every predetermined time interval (for example, several milliseconds), and the recognition information is output to the accumulated numerical value output unit 12E. Is done. Further, the operation of recognizing the operating state of the engine E may be executed for each cycle of each cylinder of the engine E.

  The accumulated numerical value output means 12E receives the output of the operating state recognition means 12D, and outputs the increased amount of particulate matter and the amount of reduced particulate matter in the DPF 15b according to the operating state of the engine E. . Specifically, a situation where PM is not burned and removed by the DPF 15b according to the operating state of the engine E recognized by the operating state recognition means 12D (a situation where the exhaust temperature does not rise such as low speed and low load). In this case, the amount of increase in particulate matter (positive value) corresponding to the operation state is converted into a numerical value and output, and PM is burned and removed by the DPF 15b (exhaust gas such as high speed and high load). When the temperature rises), the particulate matter reduction amount (negative value) corresponding to the operation state is digitized and output.

  More specifically, as shown in FIG. 5, a map for obtaining the above numerical values in accordance with the fuel injection amount and the engine speed in the main injection is stored in advance (stored in the memory in the controller 12), and according to this map The amount of increase in particulate matter and the amount of decrease in particulate matter are digitized and output. In this map, the exhaust gas temperature is relatively high in the area with the solid line, and PM is burned and removed. That is, this is an area where the DPF 15b can be regenerated without performing post injection. When the operating state of the engine is in this region, the accumulated numerical value output means 12E outputs a negative value (values “−1” to “−3” in the figure) obtained by quantifying the amount of particulate matter reduction. As can be seen from this map, this value is output as a smaller value as the engine speed is higher.

  On the other hand, in this map, the exhaust gas temperature is relatively low in the hatched area of the broken line, and PM is not removed by combustion, and PM accumulates in the DPF 15b. That is, in a situation where this state continues, the DPF 15b cannot be regenerated unless post injection is executed. When the engine operating state is in this region, the accumulated numerical value output means 12E outputs a positive value (a value of “5” or “4” in the figure) obtained by quantifying the amount of increase in particulate matter. As can be seen from this map, this value is output as a larger value as the engine speed is lower.

  As the timing of the output operation of the accumulated numerical value output means 12E, the numerical information extracted from the map is output every time the recognition information from the driving state recognition means 12D is received.

  Every time the accumulating unit 12F receives the output from the accumulated numerical value output unit 12E, the accumulating unit 12F accumulates the received numerical values. In other words, in a situation where the exhaust temperature is relatively low (the region hatched with a broken line in FIG. 5), this integrated value gradually increases (the amount of accumulated PM increases), while the exhaust temperature is relatively high. In a high situation (a region with a solid diagonal line in FIG. 5), this integrated value gradually decreases (PM is burned and removed). However, if the integrated value becomes a negative value, the integration calculation is stopped.

  The engine operation state recognition operation by the above-described operation state recognition unit 12D, the output operation of information obtained by quantifying the particulate matter increase amount and the particulate matter decrease amount by the accumulated numerical value output unit 12E, and the numerical integration operation by the integration unit 12F are as follows. This is continued during the post injection. In addition, during post-injection execution, the post-injection decrease amount output means 12J that outputs the numerical value of the decrease in the collection amount by post-injection operates to output the PM accumulation amount decrease during post-injection execution. The decrease is received by the integrating means 12F, and the integrated value operates to decrease. This makes it possible to estimate the current PM accumulation amount in consideration of the decrease in the PM accumulation amount due to the post injection.

  The determination unit 12G receives the output of the integration unit 12F, and compares the integrated value with a preset post-injection start value and post-injection stop value. As a result of the comparison, when the integrated value reaches the post injection start value, a determination signal (command signal for starting post injection) is transmitted to the post injection start means 12H. When the value is below the injection stop value, the determination signal (command signal for stopping the post injection) is transmitted to the post injection stop means 12I. These post-injection start value and post-injection stop value are preset as different values. For example, the post injection start value is “100” and the post injection stop value is “10”. These numbers are not limited to this.

  When the integrated value reaches the post injection start value and receives the determination signal from the determination unit 12G, the post injection start unit 12H drives the injector 1 to start the post injection. On the other hand, the integrated value falls below the post-injection stop value during execution of the post-injection, and the post-injection stop unit 12I that has received the determination signal from the determination unit 12G stops the post-injection of the injector 1. When the post injection of the injector 1 is stopped by the post injection stopping means 12I, the integrated value stored in the integrating means 12F is returned to the initial value “0”.

  The above is the configuration for setting the execution timing of the post injection.

  Next, the post injection execution procedure in this embodiment will be described with reference to the flowchart of FIG.

  First, in step ST1, it is determined whether or not post injection is currently being executed. That is, it is determined whether or not an operation for regenerating the DPF 15b is being executed. When this determination is No (non-execution), the process proceeds to step ST2, where the integrated value integrated by the integrating means 12F is compared with the post injection start value (execution determination value), and post injection start is started. When the value is larger or when both values are equal (when No is determined in step ST2), it is determined that the PM accumulation amount of the DPF 15b is still small, and the post injection is not executed. On the other hand, when the integrated value integrated by the integrating means 12F is larger (when determined Yes in step ST2), it is determined that the PM accumulation amount has become excessive, and the process proceeds to step ST3 to perform post injection. The post injection of the injector 1 is started by the start means 12H. That is, the regeneration operation of the DPF 15b is started.

  On the other hand, if it is determined in step ST1 that the post injection is being performed (Yes is determined), the process proceeds to step ST4, where the integrated value accumulated by the integrating means 12F and the post injection are determined. The stop value (stop determination value) is compared, and when the integrated value integrated by the integration means 12F is larger or when both values are equal (when No determination is made in step ST4), the DPF 15b It is judged that regeneration is not completed, and post injection is continued. On the other hand, if the post injection stop value is larger (Yes in step ST4), it is determined that the regeneration of the DPF 15b is completed, and the process proceeds to step ST5 where the post injection stop means 12I performs post injection. Stop. That is, the regeneration operation of the DPF 15b is finished.

  FIG. 7 is a graph showing an example of a change state of the integrated value of the integrating means 12F before and after the execution of post injection. As the operation of the engine E starts and the amount of PM in the DPF 15b gradually increases, the integrated value also gradually increases. Then, the post-injection is started when the integrated value reaches the post-injection start value (execution determination value) (timing I in the drawing). As the post injection is performed, the PM in the DPF 15b is burned and removed, and the integrated value gradually decreases. Then, the post injection is stopped when the integrated value reaches the post injection stop value (stop determination value) (timing II in the figure). By repeating this operation, the PM collection performance of the DPF 15b is maintained.

  Thus, in this embodiment, since the amount of collected PM is estimated based on the operating state of the engine E, a special sensor (pressure difference sensor or temperature sensor) for detecting the state of the DPF is not required. In addition, post injection can be executed at an appropriate timing. In addition, since it is not necessary to always perform post injection, there is no significant increase in fuel consumption.

(Modification)
Next, a modified example of the present invention will be described. In this example, the configuration and conditions for stopping the post-injection are different from those of the above-described embodiment. Other configurations and operations are the same as those of the above embodiment. Therefore, only differences from the above embodiment will be described here.

In this example, the post injection is stopped when one of the following two conditions is satisfied as a condition for stopping the post injection.
(1) The elapsed time from the start time of the post injection has reached a preset post injection completion time.
(2) The determination means 12G has determined that the integrated value of the integrating means 12F has fallen below a predetermined post-injection stop value.

  For this reason, as shown in FIG. 8, the controller 12 of this example is provided with time measuring means 12K. The time measuring means 12K measures the elapsed time since the start of post-injection. When this elapsed time reaches a preset time (for example, tens of seconds), the determining means 12G A post-injection stop signal is transmitted to the. The determination unit 12G receives the post injection stop signal and transmits a stop signal to the post injection stop unit 12I to stop the post injection.

  FIG. 9 is a flowchart of the post injection execution procedure in this example. Since the operations in steps ST1 to ST5 are the same as those in the above-described embodiment, description thereof is omitted here.

  In this example, the time measuring means 12K operates from the time when post injection is started in step ST3, and the elapsed time since the start of post injection is measured (step ST6).

  If NO is determined in step ST4 (when the integrated value accumulated by the integrating means 12F is larger than the post-injection stop value), the process moves to step ST7 and the time measuring means 12K measures. If the post-injection completion time is larger or both are equal (when No is determined in step ST7), the DPF 15b is still in the process. It is determined that the regeneration is not completed, and the post injection is continued. On the other hand, when the elapsed time measured by the time measuring means 12K is larger (when determined Yes in step ST7), it is determined that the regeneration of the DPF 15b is completed, and the process proceeds to step ST8 to perform post injection. Post injection is stopped by the stop means 12I. That is, the regeneration operation of the DPF 15b is finished.

-Other embodiments-
In the embodiment described above, the case where the present invention is applied to the pressure accumulation type fuel injection device provided in the fuel supply system of the four-cylinder industrial diesel engine has been described. The present invention is not limited to this, and can be applied to various types of engines such as a 6-cylinder marine diesel engine. Further, the present invention is not limited to industrial engines, and can be applied to engines used for other purposes such as marine and vehicle use.

It is a figure which shows the pressure accumulation type fuel injection apparatus which concerns on embodiment. It is a control block diagram for determining the fuel injection amount. It is a schematic block diagram which shows an engine main body and an exhaust system. It is a control block diagram for setting the execution timing of post injection. It is a figure which shows the map for determining the output value from a stored numerical value output means. It is a flowchart figure which shows the post injection execution procedure. It is a figure which shows an example of the change state of the integration value of the integration means by the post injection being performed. FIG. 5 is a diagram corresponding to FIG. 4 in a modified example. FIG. 7 is a diagram corresponding to FIG. 6 in a modified example.

Explanation of symbols

1 Injector (fuel injection means)
12D Operating state recognition means 12E Accumulated numerical value output means 12F Accumulation means 12G Determination means 12H Post injection start means 12I Post injection stop means 15b DPF (diesel particulate filter)
E engine (internal combustion engine)

Claims (7)

Provided in an internal combustion engine having a particulate filter that collects particulate matter in the exhaust gas in the middle of the exhaust passage, the particulate filter is heated by performing post-injection from the fuel injection means, and the collection In a fuel injection device that regenerates a particulate filter by burning and removing particulate matter that has been removed,
Operating state recognition means for recognizing the operating state of the internal combustion engine;
In response to the output of the operating state recognition means, and depending on the operating state of the internal combustion engine, the particulate matter increase amount in the particulate filter is set as a positive value, and the particulate matter decrease amount is expressed as a negative value. Accumulated numerical value output means to output,
Accumulating means for accumulating the received numerical value each time the output from the accumulated numerical value output means is received;
Determining means for receiving the output of the integrating means and determining whether or not the integrated value has reached a predetermined post-injection start value;
A post-injection start means for starting the post-injection of the fuel injection means when the integrated value reaches a predetermined post-injection start value in response to the output of the determination means ;
The operating state recognition unit is configured to recognize the operating state of the internal combustion engine by detecting the fuel injection amount in the main injection of the fuel injection unit and the engine speed of the internal combustion engine,
The accumulated numerical value output means outputs either the positive value or the negative value at a predetermined fuel injection amount at the same engine speed, and the predetermined fuel injection amount at the boundary is the engine speed. And a configuration in which the positive value is output as a larger value as the engine speed is lower, and the negative value is output as a smaller value as the engine speed is higher. the fuel injection system for an internal combustion engine, characterized in that has become. In the fuel injection device for an internal combustion engine according to claim 1,
The operation state recognition means is configured to recognize the operation state of the internal combustion engine at predetermined time intervals and output the recognition information to the accumulated numerical value output means,
Each time the accumulated numerical output means receives the recognition information from the operating state recognizing means, the particulate matter increase amount and the particulate matter decrease amount in the particulate filter are digitized according to the operation state of the internal combustion engine. it has a configuration that outputs Te fuel injection system for an internal combustion engine characterized by. In the fuel injection device for an internal combustion engine according to claim 1 or 2,
The operating state recognizing means is configured to recognize the operating state of the internal combustion engine for each cycle of each cylinder of the internal combustion engine and output the recognition information to the accumulated numerical value output means,
Each time the accumulated numerical output means receives the recognition information from the operating state recognizing means, the particulate matter increase amount and the particulate matter decrease amount in the particulate filter are digitized according to the operation state of the internal combustion engine. it has a configuration that outputs Te fuel injection system for an internal combustion engine characterized by. In the fuel injection device for an internal combustion engine according to any one of claims 1 to 3,
During post-injection of the fuel injection means, the operation state recognition operation of the internal combustion engine by the operation state recognition means, and the output operation of information obtained by quantifying the particulate matter increase amount and particulate matter decrease amount by the accumulated numerical value output means In addition to the fact that the numerical integration operation by the integration means is continuously executed, the output value by the post injection reduction amount output means for calculating the numerical value corresponding to the particulate matter reduction amount by the post injection is Accumulated in the accumulating means,
A post-injection stop means for stopping the post-injection of the fuel injection means when the determination means determines that the integrated value of the integration means has fallen below a predetermined post-injection stop value during the post injection of the fuel injection means; A fuel injection device for an internal combustion engine. In the fuel injection device for an internal combustion engine according to any one of claims 1 to 3,
Even during the post injection of the fuel injection means, the operation state recognition operation of the internal combustion engine by the operation state recognition means, the particulate matter increase amount and the particulate matter decrease amount by the accumulated numerical output means, the information output operation that is quantified, The numerical integration operation by the integration means is continuously executed,
During the post injection of the fuel injection means, the elapsed time from the start time of the post injection has reached a preset post injection completion time, or the integrated value of the integrating means falls below a predetermined post injection stop value. A fuel injection device for an internal combustion engine, comprising: a post-injection stop means for stopping post-injection of the fuel injection means when any of the conditions determined by the determination means is satisfied . In the fuel injection device for an internal combustion engine according to claim 4 or 5,
The fuel injection device for an internal combustion engine, wherein the integrated value of the integrating means is returned to the initial value when the post injection of the fuel injection means is stopped . In the fuel injection device for an internal combustion engine according to claim 4, 5 or 6,
By making the post injection start value and the post injection stop value different from each other, hysteresis is provided between the integrated value for determining the post injection start time and the integrated value for determining the post injection stop time. A fuel injection device for an internal combustion engine.

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