JP2016094889A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine that enables improvement of fuel economy and that can prevent occurrence of a dilution phenomenon of engine oil.SOLUTION: An exhaust emission control device for an internal combustion engine includes: a filter 17 disposed in an exhaust passage 11 of the internal combustion engine 1 to collect particulate matters in exhaust gas; filter regeneration determination means 30 for determining the necessity of a regeneration processing operation for regenerating the filter 17 by removing the particulate matters; temperature rise means 19 for injecting fuel to combustion gas to raise a temperature of the filter 17 when the filter regeneration determination means 30 determines that the regeneration processing operation is necessary; and a fuel container 18 for storing fuel. By using the temperature rise means 19, a first injection pattern in which fuel is injected in first injection amount per unit time and then injected in second injection amount larger than the first injection amount is intermittently repeated and the second injection amount is reduced as residual amount of the fuel stored in the fuel container 18 decreases.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine.

  Exhaust gas discharged from a diesel engine contains contaminants such as carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM). In order to prevent air pollution caused by these pollutants, technologies using an exhaust gas recirculation device (EGR), a common rail type high pressure fuel injection device, a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), etc. have been developed. Yes.

  The above-mentioned DPF is provided in the middle of the exhaust pipe of the engine and directly collects particulate matter in the exhaust gas, and is formed in a filter shape. However, since the clogging of DPF progresses as particulate matter is collected and the exhaust gas pressure rises, so-called regeneration treatment operation is required to periodically remove the collected and accumulated particulate matter. It is. In the conventional regeneration processing operation, the DPF temperature is raised to about 600 ° C. or more by raising the engine exhaust temperature by delaying the fuel injection timing or by generating heat based on the hydrocarbon supply to the DOC by post-injecting fuel. The particulate matter is burned and removed by heating. As an example of such a prior art, the undershoot amount at the time of temperature control during the regeneration processing operation is controlled to quickly and accurately control the filter within a reproducible temperature range, and the fuel injection amount required for the temperature rise of the filter is controlled. A technique capable of achieving reduction is known (see, for example, “Patent Document 1”).

Japanese Patent No. 4371405

The DPF described above has a DOC (supporting OSC material) upstream of the exhaust pipe. However, if the period of the regeneration process is long, the oxygen release amount of the DOC decreases during the regeneration process and the combustion temperature of the DPF As a result, the fuel post-injection amount increases, the injection period becomes longer, the fuel consumption deteriorates, and the engine oil dilution phenomenon (oil dilution) may occur.
SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust purification device for an internal combustion engine that can solve the above-described problems and can improve the fuel consumption and prevent the occurrence of engine oil dilution.

  According to the first aspect of the present invention, there is provided a filter that is disposed in an exhaust passage of an internal combustion engine and collects particulate matter in the exhaust, and a regeneration processing operation that removes the particulate matter and regenerates the filter. A filter regeneration determining means for determining; a temperature raising means for injecting fuel into combustion gas to raise the temperature of the filter when the filter regeneration determining means determines that the regeneration processing operation is necessary; A fuel container for storing, and the temperature raising means intermittently injects a first injection pattern in which an injection amount per unit time is injected at a first injection amount and then injected at a second injection amount that is greater than the first injection amount. The second injection amount is decreased as the remaining amount of fuel stored in the fuel container decreases.

  According to a second aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to the first aspect, the temperature raising means further reduces an injection time for injecting at the second injection amount as the remaining fuel amount decreases. It is characterized by that.

  According to a third aspect of the present invention, in the exhaust gas purification apparatus for an internal combustion engine according to the first or second aspect, the temperature raising means further comprises a first injection amount when the remaining amount of fuel becomes a predetermined amount or less. It switches to the 2nd injection pattern which makes injection intermittent.

  The invention according to claim 4 is the exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 3, further comprising a filter temperature detecting means for detecting a temperature of the filter or the vicinity of the filter, The injection time by the temperature raising means is determined based on the temperature detected by the filter temperature detecting means.

  According to the present invention, fuel consumed by post-injection can be reduced as the remaining amount of fuel decreases, so that fuel efficiency can be improved and fuel can be used at a time not intended by the driver during vehicle travel. Can be prevented from disappearing. Furthermore, since post-injection is stopped during the regeneration processing operation and oxygen is occluded in the OSC material, fuel injection by post-injection can be reduced, and engine oil dilution can be prevented.

1 is a schematic diagram of an exhaust emission control device for a diesel engine to which a first embodiment of the present invention can be applied. It is a figure explaining fuel injection in a 1st embodiment of the present invention. It is a flowchart explaining the post injection process in the 1st Embodiment of this invention. It is a diagram which shows the aspect of the fuel injection in the 1st Embodiment of this invention. It is a diagram which shows the aspect of the fuel injection in the 2nd Embodiment of this invention. It is a diagram which shows the relationship between the filter temperature and fuel injection quantity in the 6th Embodiment of this invention.

  FIG. 1 is a schematic configuration diagram of an exhaust emission control device for a diesel engine showing a first embodiment of the present invention. In the figure, a multi-cylinder diesel engine (hereinafter referred to as an engine) 1 which is an internal combustion engine has a cylinder head 2 and a cylinder block 3, and a piston 4 is disposed in a cylinder bore of the cylinder block 3 so as to be capable of reciprocating. Yes. A combustion chamber 5 is formed by the inner wall surface of the cylinder bore, the top surface of the piston 4, and the lower surface of the cylinder head 2.

  An intake port 7 that is opened and closed by an intake valve 6 is formed in the cylinder head 2, and an intake passage 8 including an intake manifold is connected to the intake port 7. Further, an exhaust port 10 that is opened and closed by an exhaust valve 9 is formed in the cylinder head 2, and an exhaust passage 11 including an exhaust manifold is connected to the exhaust port 10.

  A variable capacity turbocharger (VGT) 12 is provided between the intake passage 8 and the exhaust passage 11 so that the intake air pressurized by the VGT 12 is cooled by the intercooler 13 and supplied to the combustion chamber 5. It is configured. The intake passage 8 downstream of the intercooler 13 and the exhaust passage 11 upstream of the VGT 12 are connected by an exhaust gas recirculation passage (EGR passage) 14. The EGR passage 14 is provided with an EGR valve 15, and the amount of exhaust gas flowing through the EGR passage 14 is controlled by the EGR valve 15. Furthermore, a diesel oxidation catalyst (DOC) 16 and a diesel particulate filter (DPF) 17 are provided in the exhaust passage 11 downstream of the VGT 12 in order from the upstream side of the exhaust gas flow. The DPF 17 carries an OSC material as a catalyst.

  Further, the cylinder head 2 is provided with a fuel injection valve 19 which is an electronically controlled temperature raising means for directly injecting fuel into the combustion chamber 5 of each cylinder. The high pressure fuel controlled to the pressure of is supplied. Fuel is supplied to the common rail 20 from a fuel tank 18 that is a fuel container by a fuel supply pump 21 that is rotationally driven in conjunction with the engine 1. The fuel injection valve 19 is a control means (ECU) 30 to which an opening degree signal from an accelerator sensor (not shown) for detecting the accelerator opening degree and a rotation speed signal from a rotation speed detection sensor (not shown) for detecting the engine speed are input. Is controlled to open and close, and the fuel is injected at an injection amount corresponding to the length of the valve opening time. The ECU 30 searches for the target fuel injection amount and the target injection timing based on each input signal, and controls the opening / closing timing of the solenoid valve of the fuel injection valve 19 so as to be the target fuel injection amount and the target injection timing. A float sensor 27 that linearly detects the amount of fuel stored inside is provided in the fuel tank 18. The remaining amount of fuel detected by the float sensor 27 is input to the ECU 30 as remaining fuel information.

  Further, the ECU 30 receives a detection signal of a temperature sensor 22 as filter temperature detection means attached to the inlet of the DPF 17 in order to detect the temperature of the DPF 17. The temperature sensor 22 may be a sensor that directly detects the temperature of the DPF 17 or may estimate the temperature of the DPF 17 from an operating state or a temperature in the vicinity of the DPF 17. Reference numeral 25 denotes an electronically controlled throttle valve that is driven and controlled by the ECU 30 in accordance with the operating state of the engine 1, similarly to the EGR valve 15 and the VGT 12.

  The exhaust passage 11 is provided with a first branch passage 23 that branches at a position immediately upstream of the DOC 16 and a second branch passage 24 that branches at a position immediately downstream of the DPF 17. Is provided with a differential pressure sensor 26 for detecting the differential pressure between the branch passages 23 and 24. The detection value detected by the differential pressure sensor 26 is input to the ECU 30.

  FIG. 2 is a diagram showing the state of fuel injection by the fuel injection valve 19. Prior to the main injection in which the piston 4 is injected at the compression top dead center, pre-injection is performed in order to bring the injection rate close to the ideal state. Is called. Then, after the main injection, after injection is performed in the expansion stroke, and post injection is performed in the expansion stroke or the exhaust stroke. After-injection is performed in order to increase the temperature of the DPF 17 to some extent by supplying high-temperature exhaust gas to the DPF 17 in advance prior to post-injection. A feature of the present invention is post-injection fuel injection control performed to regenerate the DPF 17.

  Next, fuel injection control during the regeneration processing operation of the DPF 17 by the ECU 30 will be described with reference to FIG. First, initialization is performed with the ignition turned on (ST01). Here, the control parameters of the ECU 30 are returned to the initial state and prepared for the following control.

  Next, the accelerator opening and the engine speed, which are parameters for engine control, are acquired (ST02), and the total injection amount of the pre-injection and the main injection is calculated based on the acquired accelerator opening and the engine speed. (ST03). Then, the pre-injection amount and the pre-injection timing are calculated based on the total injection amount and the engine speed (ST04), and the main injection amount and the main injection timing are calculated based on the total injection amount and the engine speed. (ST05).

  Next, based on the detected value of the differential pressure sensor 26, it is determined whether or not the differential pressure across the DPF 17 is greater than a predetermined value A (ST06). This is because the ECU 30 functions as a filter regeneration determination means, and the predetermined value A is set in consideration of the upper limit value of the allowable front-rear differential pressure, so that the front-rear differential pressure, that is, the back pressure of the internal combustion engine does not become too large. Is set to If it is determined that the front-rear differential pressure is greater than the predetermined value A, it is determined that the amount of particulate matter deposited on the DPF 17 has reached the level required for regeneration of the DPF 17, and the regeneration processing operation is performed below.

  If it is determined in step ST06 that the front-rear differential pressure is greater than the predetermined value A, the regeneration processing operation waiting flag is set to fw = 1 (ST07). When the flag is set, it indicates that the DPF 17 needs to be regenerated and is referred to in another control routine or notified to the ECU in the vehicle. Next, the detected temperature detected by the temperature sensor 22 is compared with a predetermined temperature that is a threshold value to determine whether or not the detected temperature is higher than the predetermined temperature (ST08). Here, the predetermined temperature is set in consideration of the lower limit value of the temperature at which the particulate matter collected by the DPF 17 can be purified.

  Next, a flag for executing the regeneration processing operation is set (ST09), and then the post injection amount and the post injection timing are calculated based on the total injection amount and the engine speed (ST10), and further the post injection based on the detected temperature. An injection amount initial value is calculated (ST11), and an increase value per unit time of the post injection amount is calculated based on the detected temperature (ST12). Both the initial value of the post injection amount and the increase value per unit time of the post injection amount are set to smaller values as the detected temperature is lower. In this case, the ECU 30 stores a map in which the initial value of the post injection amount and the increase value per unit time of the post injection amount correspond to the detected temperature, and is set based on this map. Next, the post-injection amount during the regeneration process is reset (ST13), and after setting parameters that define the content of these regeneration process operations, the regeneration process operation is executed (ST14).

  If it is determined in step ST06 that the differential pressure before and after is smaller than the predetermined value A, this state is during the regeneration processing operation or in the non-execution state of the regeneration processing operation, and the amount of accumulated particulate matter has yet reached the necessary regeneration level. That is not. In this case, it is first determined whether or not the regeneration processing operation execution flag is set (ST15). If it is set, it is determined whether or not the differential pressure across the DPF 17 is equal to or less than a predetermined value B (ST16). The predetermined value B is set to a pressure value at which it is determined that the amount of particulate matter accumulated in the DPF 17 is sufficiently reduced and the back pressure of the internal combustion engine is sufficiently reduced. When it is determined that the front-rear differential pressure is less than or equal to the predetermined value B, it is determined that the regeneration processing operation has been completed (ST17), and when it is determined that the front-rear differential pressure is greater than the predetermined value B, the post-injection end flag It is determined whether or not is set (ST18). If it is determined that the post injection end flag is not set, the routine proceeds to step ST14 where post injection is performed.

  Here, the characteristic part in the 1st Embodiment of this invention is demonstrated. In the first embodiment of the present invention, the post injection by the fuel injection valve 19 during the regeneration processing operation of the DPF 17 is performed based on the graph shown in FIG. This post-injection is a first injection amount in which the initial fuel injection amount per unit time is suppressed as compared with the conventional case, and the fuel per unit time when the temperature of the DPF 17 detected by the temperature sensor 22 exceeds a predetermined temperature A. The injection amount is increased to a second injection amount that is larger than the first injection amount. The temperature of the DPF 17 is increased by the post injection, and the adhering particulate matter is burned and removed, and the oxygen release amount of the loaded OSC material is reduced, so that the temperature starts to decrease even if the post injection is continued. Then, when the temperature of the DPF 17 becomes equal to or lower than the predetermined temperature B, the post injection is stopped, and when the temperature further decreases and the temperature of the DPF 17 becomes equal to or lower than the predetermined temperature C, the post injection of the first injection amount is restarted. Is raised to a predetermined temperature A. By temporarily stopping the post injection, oxygen is stored in the OSC material to recover the oxygen release amount. One operation cycle including the temporary stop shown in FIG. 4 is the first injection pattern, and the first injection pattern is repeated below.

  At this time, in the second and subsequent first injection patterns, the fuel injection amount per unit time at the second injection amount is decreased based on the remaining fuel amount detected by the float sensor 27. When the value detected by the differential pressure sensor 26 is equal to or less than the predetermined value A in step ST06 shown in FIG. 3, it is determined that the particulate matter adhering to the DPF 17 has been removed, and the regeneration processing operation of the DPF 17 ends. In the first injection pattern of the first time, the injection time at the first injection amount is longer than the second time in order to wait for the temperature of the DPF 17 to rise. The injection time at the first injection amount for the second and subsequent times in the first injection pattern is the same as the second injection time.

  According to the above-described configuration, the fuel consumed by the post-injection can be reduced as the remaining amount of fuel decreases, so that fuel consumption can be improved and the vehicle is not intended when the vehicle travels. While preventing the fuel from running out, post-injection is stopped during the regeneration processing operation, and oxygen is occluded in the OSC material, so that it is possible to prevent the engine oil from being diluted.

  In the first embodiment, as a method of reducing the fuel injection amount per unit time at the second injection amount in the first injection pattern, the fuel supply pressure from the common rail 20 is reduced to reduce the fuel from the fuel injection valve 19. A method of reducing the injection amount, a method of shortening the opening / closing time of the solenoid valve of the fuel injection valve 19 to shorten the fuel injection time, and a method of using both in combination. According to the method of reducing the injection amount, the height of the first injection pattern in FIG. 4 at the second injection amount is reduced, and according to the method of shortening the fuel injection time, the second injection of the first injection pattern in FIG. The injection time by the amount is reduced, and the total fuel injection amount (area) at the second injection amount of the first injection pattern is reduced by any method.

  Next, a second embodiment of the present invention will be described. In the second embodiment, post injection by the fuel injection valve 19 during the regeneration processing operation of the DPF 17 is performed based on the graph shown in FIG. 5 in addition to intermittently repeating the first injection pattern described above. In the post-injection shown in FIG. 5, the initial fuel injection amount per unit time is set as the first injection amount described above, and the post-injection is stopped when the temperature of the DPF 17 detected by the temperature sensor 22 exceeds the predetermined temperature A. Thereafter, when the temperature of the DPF 17 becomes equal to or lower than the predetermined temperature B, the post injection is resumed and the temperature of the DPF 17 is raised to the predetermined temperature A. A method of intermittently post-injecting the first injection amount is the second injection pattern. By temporarily stopping the post injection, oxygen is stored in the OSC material to recover the oxygen release amount.

  In the second embodiment, post injection is performed in which the first injection pattern shown in the first embodiment described above is intermittently repeated, and the remaining amount of fuel detected by the float sensor 27 is a predetermined amount (for example, 10 liters). ) When the following occurs, switch to the second injection pattern and perform post injection. When the value detected by the differential pressure sensor 26 is equal to or less than the predetermined value A in step ST06 shown in FIG. 3, it is determined that the particulate matter adhering to the DPF 17 has been removed, and the regeneration processing operation of the DPF 17 ends. The first post injection in the second injection pattern is longer than the second in order to wait for the temperature of the DPF 17 to rise. The second and subsequent post injections have the same injection time as the second injection.

  According to the above-described configuration, the fuel consumed by the post injection can be reduced as the remaining amount of fuel decreases, and further consumed by the post injection when the remaining fuel amount becomes a predetermined amount or less. Since fuel can be reduced, fuel consumption can be further improved, and post-injection is stopped during regeneration processing while reliably preventing fuel from running out at times not intended by the driver during vehicle travel. Since the OSC material stores oxygen, the engine oil dilution phenomenon can be prevented.

  In each of the first and second embodiments described above, an example in which post-injection is performed as the regeneration processing operation of the DPF 17 has been described. However, the scope of application of the present invention is not limited to post-injection, and direct fuel injection into the exhaust pipe The present invention can also be applied to the exhaust pipe injection for performing the above.

  Next, a third embodiment of the present invention will be described. In the third embodiment, the remaining amount of the particulate matter remaining in the DPF 17 is estimated based on the detection value detected by the differential pressure sensor 26 with a predetermined load, and based on this remaining amount, the DPF 17 The post injection method during the regeneration processing operation is changed. In this third embodiment, the differential pressure sensor 26 functions as a remaining amount detecting means, and the ECU 30 estimates the remaining amount of particulate matter remaining in the DPF 17 from the detection value of the differential pressure sensor 26. The relationship between the detected value of the differential pressure sensor 26 and the remaining amount of the particulate matter is mapped and stored in the storage means in the ECU 30.

  In the third embodiment, post injection by the fuel injection valve 19 during the regeneration processing operation of the DPF 17 is performed when the remaining amount of particulate matter remaining in the DPF 17 is equal to or greater than the predetermined value Z. The injection pattern is intermittently repeated, and when it is less than the predetermined value Z, the above-described second injection pattern is used. When the value detected by the differential pressure sensor 26 is equal to or less than the predetermined value A in step ST06 shown in FIG. 3, it is determined that the particulate matter adhering to the DPF 17 has been removed, and the regeneration processing operation of the DPF 17 ends.

  According to the above-described configuration, when the remaining amount of the particulate matter is large, a large amount of fuel is injected to remove the particulate matter in a short time, and when the remaining amount of the particulate matter is small, the amount of fuel is small. Since particulate matter is removed, fuel consumption can be improved and post-injection is stopped during the regeneration processing operation, and oxygen is occluded in the OSC material, thereby preventing the occurrence of engine oil dilution. it can.

  Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, in addition to the control shown in the third embodiment, the predetermined value Z is changed based on the remaining fuel amount detected by the float sensor 27, and the predetermined value is decreased as the remaining fuel amount decreases. Increase Z. According to this configuration, in addition to the operational effects shown in the third embodiment, the selection range of the second injection pattern that consumes less fuel as the remaining amount of fuel decreases becomes wider, so that fuel efficiency can be improved. At the same time, it is possible to prevent the fuel from running out when the vehicle is not intended.

  Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, in addition to the control shown in the third or fourth embodiment, when the remaining amount of fuel detected by the float sensor 27 falls below a predetermined amount (for example, 10 liters), the second Switch to the injection pattern and perform post injection. According to this configuration, in addition to the operational effects shown in the third or fourth embodiment, when the remaining fuel amount becomes a predetermined amount or less, the fuel consumed by the post injection can be further reduced. In addition, fuel consumption can be further improved and fuel can be reliably prevented from running out at a time unintended by the driver during vehicle travel.

  In each of the third, fourth, and fifth embodiments described above, the example in which the post injection is performed as the regeneration processing operation of the DPF 17 has been shown. However, the range in which the present invention can be applied is not limited to the post injection, but in the exhaust pipe. The present invention can also be applied to exhaust pipe injection in which direct fuel injection is performed.

  Next, a sixth embodiment of the present invention will be described. In the sixth embodiment, as shown in FIG. 1, a timer 28 is provided as stop time detecting means for detecting the stop time of the engine 1, and the detection result of the timer 28 is input to the ECU 30. The sixth embodiment is applied when the engine 1 is stopped after the regeneration processing operation of the DPF 17 is started and the regeneration processing operation of the DPF 17 is performed again after the engine 1 is restarted.

  In the sixth embodiment, post injection by the fuel injection valve 19 during the regeneration processing operation of the DPF 17 is performed based on the graph shown in FIG. In the post-injection shown in FIG. 5, the initial fuel injection amount per unit time is the first injection amount that is smaller than the conventional fuel injection amount, and the temperature of the DPF 17 detected by the temperature sensor 22 is equal to or higher than the predetermined temperature A. By the way, the post injection is stopped, and then the post injection is restarted when the temperature of the DPF 17 becomes equal to or lower than the predetermined temperature B, and the temperature of the DPF 17 is raised to the predetermined temperature A. The following is an injection pattern in which this operation is repeated intermittently. By temporarily stopping the post injection, oxygen is stored in the OSC material to recover the oxygen release amount.

  In the sixth embodiment, the ECU 30 determines the fuel injection amount per unit time from the fuel injection valve 19 when the regeneration process operation of the DPF 17 is restarted when the engine 1 is restarted after stopping based on the detection result of the timer 28. The increase control is performed as shown by the solid line in FIG. 6 in comparison with the fuel injection amount per unit time from the fuel injection valve 19 during the regeneration processing operation of the DPF 17 before the engine 1 is stopped.

  In FIG. 6, the broken line indicates the estimated temperature of the DPF 17. In this embodiment, since the engine 1 is stopped, no exhaust gas flows, and the temperature of the DPF 17 cannot be measured by the temperature sensor 22. For this reason, the temperature of the DPF 17 is estimated based on the stop time of the engine 1 measured by the timer 28, and the ECU 30 performs the increase control of the fuel injection amount based on the estimated temperature.

  As shown in FIG. 6, the temperature of the DPF 17 maintains the regeneration processing temperature (about 650 ° C. in this embodiment) for a while after the engine 1 is stopped, and rapidly decreases after a predetermined time Y. For this reason, when the stop time of the engine 1 measured by the timer 28 is within the predetermined time Y, the temperature of the DPF 17 does not decrease so much. The fuel injection amount per unit time is not increased. In this way, the temperature of the DPF 17 is estimated from the stop time of the engine 1, and in the region where the temperature of the DPF 17 has not decreased so much, the fuel injection amount per unit time from the fuel injection valve 19 is larger than that before the stop of the engine 1. Since the increase is not performed, fuel consumption can be improved.

  Further, as shown in FIG. 6, when the stop time of the engine 1 exceeds a predetermined time Y, the temperature of the DPF 17 rapidly decreases. The fuel injection amount per unit time from the injection valve 19 is increased proportionally. With this configuration, it is possible to compensate for the temperature drop of the DPF 17 caused by stopping the engine 1 by increasing the exhaust gas temperature, and to improve the fuel efficiency by efficiently performing the regeneration processing operation of the DPF 17 with an appropriate fuel. . Further, since the post-injection is stopped during the regeneration processing operation and oxygen is stored in the OSC material, it is possible to prevent the occurrence of engine oil dilution.

  Next, a seventh embodiment of the present invention will be described. In the sixth embodiment, the predetermined time Y indicates a time estimated that the temperature of the DPF 17 rapidly decreases. In the seventh embodiment, a temperature sensor (not shown) that measures the outside air temperature is provided, and the predetermined time Y is set short each time the outside air temperature decreases by a predetermined temperature. By adopting this configuration, it is possible to estimate the temperature drop of the DPF 17 according to the drop in the outside air temperature, and even if the outside air temperature changes, the engine 1 is in a region where the temperature of the DPF 17 does not drop so much. Since the fuel injection amount per unit time from the fuel injection valve 19 is not increased as compared to before the stop, the fuel consumption can be improved, and the exhaust gas temperature is raised in the region where the temperature of the DPF 17 rapidly decreases. As a result, the temperature drop of the DPF 17 due to the stop of the engine 1 can be compensated, and the fuel consumption can be improved by efficiently performing the regeneration processing operation of the DPF 17 with an appropriate fuel.

  Next, an eighth embodiment of the present invention will be described. In the eighth embodiment, in addition to the post-injection control from the fuel injection valve 19 shown in the sixth or seventh embodiment, the predetermined time Y is changed based on the remaining fuel amount detected by the float sensor 27. The predetermined time Y is lengthened as the remaining fuel amount decreases. According to this configuration, in addition to the operational effects shown in the sixth or seventh embodiments, since the DPF 17 does not shift to the regeneration processing operation as the remaining fuel amount decreases, the fuel consumption can be improved. In addition, fuel can be prevented from running out at times not intended by the driver during vehicle travel.

  Next, a ninth embodiment of the present invention will be described. In the ninth embodiment, the vehicle having the engine 1 has a coast idle stop function that stops the engine 1 when the vehicle speed becomes a predetermined speed (for example, 10 km / h) or less when the vehicle is running. When the coast idle stop function is manifested, the low-temperature exhaust gas flows into the DPF 17, so that the temperature drop of the DPF 17 is accelerated. Therefore, the predetermined time Y is shortened when the coast idle stop function is manifested. According to this configuration, in addition to the operational effects shown in the sixth, seventh, and eighth embodiments, the fuel injection is performed in a state where the temperature of the DPF 17 does not decrease so much when the coast idle stop function in which the temperature of the DPF 17 is rapidly decreased is exhibited. Since the post-injection from the valve 19 is performed, fuel efficiency can be improved by efficiently performing the regeneration processing operation of the DPF 17 with an appropriate fuel.

  In the sixth, seventh, eighth and ninth embodiments described above, the engine 1 is stopped after the regeneration processing operation of the DPF 17 is started, and then the regeneration processing operation of the DPF 17 is performed again after the engine 1 is restarted. The case where the regeneration processing operation flag of the DPF 17 is set and the regeneration processing operation is not performed before the engine 1 is stopped is not included. That is, it is a precondition that the temperature of the DPF 17 has risen to the temperature at which the regeneration process can be performed. Further, when the engine 1 is stopped, in addition to the coast idle stop function appearing in the ninth embodiment, when the idle stop function is manifested, the engine 1 is stopped once and then the engine 1 is started again. This includes all cases where the engine 1 is started after being stopped.

  In each of the sixth, seventh, eighth, and ninth embodiments described above, post injection by the fuel injection valve 19 during the regeneration processing operation of the DPF 17 is performed based on the graph shown in FIG. The mode is not limited to this, and any post-injection may be performed as long as the fuel is intermittently injected at a predetermined injection amount per unit time. Further, in each of the sixth, seventh, eighth, and ninth embodiments, the example in which the post injection is performed as the regeneration processing operation of the DPF 17 has been shown. However, the applicable range of the present invention is not limited to the post injection, The present invention is also applicable to exhaust pipe injection in which fuel is directly injected into the exhaust pipe.

1 Internal combustion engine
11 Exhaust passage 17 Filter (DPF)
18 Fuel container (fuel tank)
19 Temperature raising means (fuel injection valve)
22 Filter temperature detection means (temperature sensor)
30 Filter regeneration judgment means (ECU)

Claims (4)

A filter that is disposed in an exhaust passage of the internal combustion engine and collects particulate matter in the exhaust; filter regeneration judgment means that judges whether or not a regeneration processing operation for removing the particulate matter and regenerating the filter is necessary; A temperature raising means for injecting fuel to combustion gas to raise the temperature of the filter when the regeneration judgment operation is judged to be necessary by the filter regeneration judging means; and a fuel container for storing fuel,
The temperature raising means intermittently repeatedly performs a first injection pattern in which an injection amount per unit time is injected at a first injection amount and then injected at a second injection amount larger than the first injection amount, and the fuel An exhaust emission control device for an internal combustion engine, wherein the second injection amount is decreased as the remaining amount of fuel stored in the container decreases. The exhaust gas purification apparatus for an internal combustion engine according to claim 1,
The internal combustion engine exhaust gas purification apparatus according to claim 1, wherein the temperature raising means reduces an injection time for injection at the second injection amount as the remaining fuel amount decreases. The exhaust gas purification apparatus for an internal combustion engine according to claim 1 or 2,
The exhaust gas purification apparatus for an internal combustion engine, wherein the temperature raising means switches to a second injection pattern for intermittently injecting the fuel at the first injection amount when the fuel remaining amount becomes a predetermined amount or less. The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 3,
An internal combustion engine comprising: a filter temperature detecting means for detecting a temperature of the filter or the vicinity of the filter; and an injection time by the temperature raising means is determined based on a temperature detected by the filter temperature detecting means. Exhaust purification equipment.

Images