JP2019100323A - Control device for engine - Google Patents

Abstract

To suppress an increase in collection amount of a soot in a particulate filter or reduce the collection amount while protecting the particulate filter even when the collection amount increases.SOLUTION: Fuel cut is performed during deceleration of an engine E. When collection amount of soot in a GPF 33 disposed in an exhaust passage 30 becomes larger than a first predetermined value, regeneration of the GPF 33 is performed (for example, post injection or retard injection of fuel). When the collection amount of the soot becomes larger than a second predetermined value larger than the first predetermined value, control for increasing the amount of exhaust gas caused to flow into the GPF 33 is performed while the execution of the regeneration control is allowed. The control for increasing the exhaust gas amount is performed through, for example, increase correction of idling speed or increase correction of speed of return from fuel cut.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device of an engine.

  For example, in an engine using gasoline as a fuel, a particulate filter (GPF) is provided in the exhaust passage to remove soot (particulate matter = particulate) in the exhaust gas, and soot in the exhaust gas is removed. It is being collected. When the soot amount collected by the particulate filter becomes equal to or more than a predetermined value, regeneration of the particulate filter (for example, post injection or retard injection of fuel) is performed.

  Patent Document 1 discloses a diesel engine in which a particulate filter (DPF) is disposed in an exhaust passage. In Patent Document 1, when the amount of soot collected by the particulate filter is increased, the possibility that the trapped soot will cause rapid combustion is increased, thereby increasing the exhaust gas flow rate. Has been carried out (suppression of temperature rise of particulate filter).

Patent No. 4453718 gazette

  By the way, the regeneration of the particulate filter is performed when the soot collection amount becomes equal to or more than a first predetermined value set in advance. Then, when the soot collection amount becomes equal to or greater than the second predetermined value larger than the first predetermined value, the regeneration control of the particulate filter is prohibited and the warning lamp is turned on, and the selling point of the vehicle (early The driver is urged to go to a dealer or the like for maintenance and inspection of the particulate filter. In particular, for example, when a running state in which the regeneration of the particulate filter is hardly performed continues, for example, when “slightly riding” is frequently performed, the amount of trapping by the particulate filter increases. The collected amount may become equal to or more than the second predetermined value.

  However, even if the warning lamp is turned on when the collection amount becomes equal to or more than the second predetermined value, depending on the driver, the vehicle may travel for a considerably long period while being left as it is. In this case, just waiting for maintenance and inspection at the sales point (dealer) of the vehicle or the like in a state where regeneration control is prohibited, the amount of collection will increase early. Then, when the amount of collection becomes extremely large, for example, when a large amount of air is introduced to the particulate filter by the fuel cut at the time of deceleration, the large amount of collected soot is burned rapidly to damage the particulate filter ( It may also cause the heat damage due to high heat).

  The present invention has been made in consideration of the above circumstances, and an object thereof is to collect the particulate filter while protecting the particulate filter even when the amount of soot collected by the particulate filter is increased. It is an object of the present invention to provide a control device of an engine which can suppress the increase of the engine speed or reduce the collection amount.

In order to achieve the above object, the following solutions are adopted in the present invention. That is, as described in claim 1,
A particulate filter disposed in the exhaust passage of the engine;
Control means for controlling the engine;
Equipped with
The control means
Estimation control for estimating the amount of soot collected by the particulate filter;
Regeneration control that causes the particulate filter to be regenerated when the soot collection amount estimated by the estimation means becomes larger than a first predetermined value;
Fuel cut control that cuts off fuel when the engine decelerates,
When the collected amount of soot estimated by the estimation means becomes larger than a second predetermined value larger than the first predetermined value, the particulate matter flows into the particulate filter while permitting execution of the regeneration control. Exhaust gas amount increase control to increase the amount of exhaust gas
Is set to do,
It is done like that.

  According to the solution method described above, when the amount of soot collected by the particulate filter becomes larger than the second predetermined value, the temperature rise of the particulate filter is suppressed by performing control to increase the exhaust gas amount. Alternatively, it can be lowered to protect it. In addition, even when the control to increase the amount of exhaust gas (protection control of the particulate filter) is performed, the execution of regeneration control is permitted, so that the increase in the amount collected by the particulate filter is suppressed or The amount of soot can be reduced, which leads to prolonging the time until maintenance or inspection of the particulate filter or eliminating the need for this maintenance and inspection, which is extremely preferable. .

  Preferred embodiments based on the above solution method are as described in claim 2 and the following claims.

  The idle rotational speed is corrected to rise by the exhaust gas amount increase control (corresponding to claim 2). In this case, the amount of exhaust gas can be increased by a simple method of increasing and correcting the idle speed.

The control means is adapted to perform fuel return control for resuming fuel supply when the engine speed is reduced to a predetermined return speed by the fuel cut control.
The return rotational speed is raised and corrected by the exhaust gas amount increase control.
(Claim 3). In this case, the amount of exhaust gas can be increased by a simple method of increasing and correcting the return rotation speed from the fuel cut.

  The exhaust gas amount increase control is performed on the condition that the temperature of the particulate filter is higher than a predetermined temperature (corresponding to claim 4). In this case, when the temperature of the particulate filter is lower than a predetermined temperature (for example, 800 to 850 ° C.), the amount of air in the exhaust gas, for example, due to fuel cut, even if the amount of collected soot is very large. Since the trapped soot is not burned rapidly even if the amount of hydrogen increases, it is preferable to prevent the exhaust gas amount increase control from being performed unnecessarily.

Equipped with a warning lamp
The control means performs lighting control to light the warning lamp when the collected amount of soot estimated by the estimation means becomes larger than the second predetermined value.
It corresponds (claim 5 correspondence). In this case, it is possible to make the driver clearly recognize that a large amount of soot is collected in the particulate filter. As a result, in order to prompt maintenance and inspection at a vehicle selling point etc. at an early stage, or prompting the driver to perform feasible operation of the regeneration control, the increase in the burden is suppressed or the burden is reduced. In order to reduce the

  According to the present invention, even when the amount of soot collected by the particulate filter is increased, the increase in the amount of trapping can be suppressed or the amount of trapping can be reduced while protecting the particulate filter.

The figure which shows the example of whole system | strain of the engine to which this invention was applied. The figure which shows the correspondence of the amount of control collected by GPF, and the control content. The figure which shows the temperature fall of GPF by raising idle rotation speed. The figure which shows the correlation with idle rotation speed and GPF temperature. The figure which shows the fall of the GPF temperature by reducing the entrance temperature of GPF. The figure which shows correlation with GPF entrance temperature and GPF temperature. The figure which shows the example of a control system of this invention. The flowchart which shows the example of control of this invention.

  In FIG. 1, E is an engine (engine main body), and FIG. 1 is a cross-sectional view focusing on a certain cylinder. The engine E is an in-line four-cylinder four-cycle engine fueled by gasoline or the like.

  In FIG. 1, 1 is a cylinder, 2 is a cylinder head, and 3 is a piston slidably fitted in the cylinder 1. The piston 3 is interlocked with the crankshaft 4 via a connecting rod (not shown).

  A combustion chamber 5 is formed in the space above the piston 3 by the cylinder 1, the cylinder head 2 and the piston 3. An intake port 6 and an exhaust port 7 are opened in the combustion chamber 5. The intake port 6 is opened and closed by the intake valve 8, and the exhaust port 7 is opened and closed by the exhaust valve 9.

  The cylinder head 2 is provided with a spark plug 10, a fuel injection valve 11, and a pressure sensor 12 for detecting the pressure in the cylinder substantially at the center of the combustion chamber 5. In the embodiment, the engine E is a four-valve engine having two intake ports 6 (intake valves 8) and two exhaust ports 7 (exhaust valves 9) for one cylinder. The two intake valves 8 are spaced from each other in the axial direction of the crankshaft 4, and similarly, the two exhaust valves 9 are spaced from each other in the axial direction of the crankshaft 4.

  The ISG 14 is interlocked with the crankshaft 4 via the belt 13. The ISG 14 is a device that doubles as a starter motor and a generator (alternator or generator). That is, when the ignition switch is turned on, the engine E is started by driving the ISG 14. Further, during traveling, for example, at the time of deceleration, power generation is performed by the ISG 14 to perform regeneration (the regenerative energy is used to charge a battery, a capacitor, or the like, or supplied to various electric devices).

  An intake passage 20 is connected to the intake port 6. In the intake passage 20, an air cleaner 21, a throttle valve 22, a supercharger 23, and an intercooler 24 are disposed sequentially from the upstream side to the downstream side. Reference numeral 25 denotes a motor for driving the supercharger 23. A bypass passage 26 is connected to the intake passage 20. The upstream end of the bypass passage 26 is open to the intake passage 20 between the throttle valve 22 and the supercharger 23. Further, the downstream end of the bypass passage 26 is opened to the intake passage 20 at the downstream side of the intercooler 24. A bypass valve 27 is disposed in the bypass passage 26.

  An exhaust passage 30 is connected to the exhaust port 7. The upstream end of the exhaust passage 30 is constituted by an exhaust manifold 31 common to the respective cylinders. In the exhaust passage 30, a small capacity first three-way catalyst 32, a GPF (particulate filter) 33, and a large capacity second three-way catalyst 34 are disposed sequentially from the upstream side toward the downstream side. . The GPF 33 collects particulates in the exhaust gas. Then, the amount of soot deposited on the GPF 33 is detected based on the detection signal from the pressure sensor 35 that detects the pressure difference between the upstream side and the downstream side of the GPF 33.

  The intake passage 20 and the exhaust passage 30 are connected via an EGR passage 40. The upstream end of the EGR passage 40 is open to the exhaust passage 30 between the GPF 33 and the second three-way catalyst 34. The downstream end of the EGR passage 40 is opened to the upstream side of the bypass valve 27 in the bypass passage 26. Then, an EGR cooler 41 and an EGR valve 42 are disposed in the EGR passage 40 sequentially from the upstream side to the downstream side.

  The engine E as described above uses gasoline as fuel and has an extremely lean air-fuel ratio (for example, an air-fuel ratio in a predetermined operating range (for example, a range where an accelerator opening is less than a predetermined opening and an engine speed is less than a predetermined engine speed) Is about 30) and compression self-ignition may be performed (in some cases, compression self-ignition may be promoted using the fire species generated by the ignition of the spark plug 10). And, except for the above-mentioned predetermined operation range, combustion is carried out by the spark ignition system by ignition of the spark plug 10 (the air-fuel ratio is mainly in the vicinity of the theoretical air-fuel ratio) as in a normal gasoline engine. For this reason, the geometric compression ratio of the engine E is set to be considerably higher than that of a normal gasoline engine (for example, the geometric compression ratio is 18 or more and the effective compression ratio is 16 or more).

  The supercharger 23 is operated to secure a large amount of air required when performing the above-described compression auto-ignition, and at this time, the bypass valve 27 is closed. On the other hand, in the operation region where ignition is performed by spark ignition, the operation of the supercharger 23 is stopped and the bypass valve 27 is opened.

  Here, the GPF 33 needs to be regenerated at an appropriate timing because the amount of collected soot increases by continuing the operation. The regeneration of the GPF 33 is performed by burning the soot with the GPF 33 by the post injection of fuel and the retard of the fuel injection timing. The regeneration of the GPF 33 is performed when the engine is in a predetermined operation range (for example, steady traveling except during acceleration, deceleration, the accelerator opening is equal to or greater than the predetermined opening, and the engine rotational speed is predetermined). When all the conditions of being equal to or higher than the rotation speed are satisfied).

  Next, with reference to FIG. 2, an outline of control contents according to the amount of collected soot (the amount of deposition) in the GPF 33 will be described. First, three threshold values of SLM1, SLM2, and SLM3 are set as the amount of collection of soot on the GPF 33 in ascending order from the smaller one (SLM1 <SLM2 <SLM3).

  When the collected amount of soot is equal to or less than the SLM 1, the collected amount is small, and the regeneration of the GPF 33 is not performed (a state where the collected amount of soot in the GPF 33 increases according to traveling).

  When the amount of soot collected by the GPF 33 is larger than that of the SLM 1 and smaller than or equal to the SLM 2, regeneration of the GPF 33 is performed (execution of post injection or retarded injection in normal reproduction).

  When the amount of soot collected by the GPF 33 is larger than that of the SLM 2 and not more than the SLM 3, regeneration of the GPF 33 is performed while performing protection control to prevent thermal damage to the GPF 33. This protection control can be roughly classified into the following first and second two methods as appropriate. In this case, the warning lamp S4 is turned on because the driver is in a situation where the amount of soot collected by the GPF 33 is too large. The lighting of the warning lamp S4 prompts the driver to drive to become the regeneration execution area of the GPF 33, and visit the vehicle selling point (dealer) at an early stage to receive maintenance and inspection of the GPF 33. Prompted.

  First, protection control of the GPF 33 is to increase the flow rate of exhaust gas flowing into the GPF 33 (to release the temperature of the GPF 33 into the exhaust gas). The exhaust gas flow rate can be increased, for example, by increasing the return rotation speed at the time of fuel cut or by increasing the idle rotation speed.

  In FIG. 3, fuel cut is started from a state where engine speed is increased by running after warm-up operation (time t1), fuel cut is canceled at time t2, and then idle speed is restored. Show the process of The temperature of the GPF 33 (main part = filter part) is lowered from T11 to T12 by increasing the number of revolutions after returning from the fuel cut or increasing the number of idle revolutions, thereby protecting the GPF 33. FIG. 4 shows the relationship between the idle speed and the maximum temperature of the GPF 33, and shows that the temperature of the GPF 33 is greatly reduced by reducing the idle speed.

  Second, protection control of the GPF 33 is control to suppress the temperature rise of the GPF 33 by output control of the engine. The output control of the engine can be performed, for example, by reducing the engine torque than the target torque or enriching the air-fuel ratio.

  In FIG. 5, the fuel cut is started from the state where the engine speed is increased by running after the warm-up operation (time t1), the fuel cut is canceled at time t2, and then the idle speed is restored. Show the process of By reducing the engine torque from the target torque or enriching the air-fuel ratio, the inlet temperature T1 of the GPF 33 decreases as indicated by T2, and accordingly, the temperature of (the main body portion = filter portion) of the GPF 33 decreases. The protection from GPF 33 is achieved by lowering from T11 to T12. FIG. 6 shows the relationship between the inlet temperature of GPF 33 and the maximum temperature of (the main body of) GPF 33, and shows that the temperature of GPF 33 is greatly reduced by decreasing the inlet temperature of GPF 33.

  When the amount of soot collected by the GPF 33 is larger than that of the SLM 3, regeneration of the GPF 33 is prohibited and fuel cut performed at the time of deceleration is prohibited (preventing a situation where the GPF 33 is thermally damaged) . In addition, when the fuel cut is prohibited at the time of deceleration, regeneration by causing the ISG 14 to function as a generator is performed to secure a necessary deceleration. Also, the warning lamp S4 is on, but the regeneration control of the GPF 33 is prohibited, and the amount of soot collected is increasing, so we go to the vehicle selling point (dealer) earlier to maintain and inspect the GPF 33 The warning lamp S4 can be lighted in a blinking state so as to strongly prompt the user to receive the warning.

  FIG. 7 shows an example of a control system for performing the control described above. In the figure, U is a controller configured using a microcomputer. In addition to the signal from the pressure sensor 35 for detecting the amount of soot collected by the GPF 33 described above, the controller U receives signals from various sensors S1 to S3. S1 is a rotational speed sensor that detects an engine rotational speed. S2 is an accelerator opening sensor that detects the accelerator opening. S3 is a temperature sensor that detects the inlet temperature of the GPF 33 (in the embodiment, the temperature immediately upstream of the first three-way catalyst 32). The controller U controls the warning lamp S4 in addition to controlling the fuel injection valve 11 and the ISG 14.

  Next, control contents of the controller U will be described with reference to FIG. In the following description, Q indicates a step. First, after the signals from various sensors and the like are read in Q1, the target torque is calculated in Q2. The target torque is basically set using the engine speed and the accelerator opening as parameters, and is further corrected by the intake air temperature, the engine coolant temperature, and the like. In addition, since the method itself of calculating (setting) a target torque is variously proposed conventionally, the description beyond this is abbreviate | omitted.

  In Q3, the amount of soot collected by the GPF 33 is estimated based on the signal from the pressure sensor 35. After Q3, in Q4, it is determined whether the soot collection amount estimated in Q3 is larger than a predetermined value SLM3. When the determination of Q4 is NO, it is determined in Q5 whether the soot collection amount is larger than SML1. When the determination of Q5 is NO, fuel injection control is performed in Q6 according to the target torque. The target torque from Q5 to Q6 is the target torque set in Q2, and the target torque is not reduced.

  If YES in the determination of Q5, regeneration of the GPF 33 is executed in Q7 (execution of post injection or retard injection). Thereafter, in Q8, it is determined whether the amount of collected soot is larger or larger than SML2. If the result of the determination of Q8 is NO, then the process shifts to Q6.

  When the determination of Q8 is YES, the warning lamp S4 is turned on in Q9. Thereafter, in Q10, it is determined whether or not acceleration is in progress. If YES in the determination of Q10, the target torque set in Q2 is corrected in Q11 so as to decrease by a predetermined amount. After this, it shifts to Q6. The decrease of the target torque in Q11 suppresses the increase of (the inlet temperature of) the GPF 33, thereby protecting the GPF 33. The process from Q11 to Q6 corresponds to the state in which the inlet temperature of GPF 33 is reduced from T1 to T2 in FIG. 5 (as a result, the state in which the temperature of GPF 33 is reduced from T11 to T12) doing).

  When the determination of Q10 is NO, it is determined in Q12 whether it is time to cut the fuel at the time of deceleration. When the determination of Q12 is NO, the process is shifted to Q6 (the target torque set in Q2 is executed in Q6).

  If the determination of Q12 is YES, fuel cut is performed in Q13. After that, in Q14, the return rotational speed from the fuel cut is corrected to a large rotational speed which is higher by a predetermined amount than that at the normal time. Thereafter, in Q15, it is determined whether or not the engine speed has decreased to the return speed corrected to be increased in Q14. If NO in the determination of Q15, the process returns to Q13.

  If the determination in Q15 is YES, fuel injection is resumed in Q16. After that, in Q17, the idle speed is corrected to rise. The process from Q12 to Q17 corresponds to the state in which the engine speed is corrected to increase from N1 to N2 in FIG. 3 (as a result, it corresponds to the state in which the temperature of GPF 33 decreases from T11 to T12) doing).

  If YES in the determination of Q4, the warning lamp S4 is turned on in Q18, and the reproduction of the GPF 33 is prohibited. It is preferable to turn on the warning lamp S4 in Q18 so as to give a stronger warning than the warning by turning on Q9. After Q18, fuel cut at deceleration is prohibited in Q19. In addition, since fuel cut is not performed at the time of deceleration in Q20, regeneration by ISG 14 is performed to compensate for the decrease in deceleration.

  Although the embodiments have been described above, the present invention is not limited to the embodiments, and appropriate modifications can be made within the scope of the claims. For example, in Q11 of FIG. 8, it is also possible to make a correction to make the air-fuel ratio rich. In Q20 of FIG. 8, instead of or in addition to the fuel cut prohibition at the time of deceleration, the air fuel ratio leaning (especially the extreme return for compression self-ignition) is prohibited and the air fuel ratio is set to λ = 1, for example. Alternatively, it may be set in the vicinity (performs ordinary spark-ignition ignition). The engine may perform only ignition by spark ignition without performing compression self-ignition. The process of Q14 and Q17 (exhaust gas amount increase control) or the process of Q19 and 20 may be executed on condition that the GPF 33 (particulate filter) is at a predetermined temperature or higher. The engine may be a diesel engine (particulate filter is DPF). Of course, the object of the present invention is not limited to what is explicitly stated, but implicitly also includes providing what is substantially preferred or expressed as an advantage.

  The present invention is suitably applied to a vehicle having a particulate filter.

E: Engine U: Controller S1: Sensor (engine speed)
S2: Sensor (accelerator opening)
S3: Sensor (GPF entrance temperature)
S4: warning lamp 11: fuel injection valve 14: ISG (starter motor and generator)
30: Exhaust passage 33: GPF (particulate filter)
35: Pressure sensor (for detecting the amount of soot collected)

  The present invention relates to a control device of an engine.

  For example, in an engine using gasoline as a fuel, a particulate filter (GPF) is provided in the exhaust passage to remove soot (particulate matter = particulate) in the exhaust gas, and soot in the exhaust gas is removed. It is being collected. When the soot amount collected by the particulate filter becomes equal to or more than a predetermined value, regeneration of the particulate filter (for example, post injection or retard injection of fuel) is performed.

  Patent Document 1 discloses a diesel engine in which a particulate filter (DPF) is disposed in an exhaust passage. In Patent Document 1, when the amount of soot collected by the particulate filter is increased, the possibility that the trapped soot will cause rapid combustion is increased, thereby increasing the exhaust gas flow rate. Has been carried out (suppression of temperature rise of particulate filter).

Patent No. 4453718 gazette

  By the way, the regeneration of the particulate filter is performed when the soot collection amount becomes equal to or more than a first predetermined value set in advance. Then, when the soot collection amount becomes equal to or greater than the second predetermined value larger than the first predetermined value, the regeneration control of the particulate filter is prohibited and the warning lamp is turned on, and the selling point of the vehicle (early The driver is urged to go to a dealer or the like for maintenance and inspection of the particulate filter. In particular, for example, when a running state in which the regeneration of the particulate filter is hardly performed continues, for example, when “slightly riding” is frequently performed, the amount of trapping by the particulate filter increases. The collected amount may become equal to or more than the second predetermined value.

  However, even if the warning lamp is turned on when the collection amount becomes equal to or more than the second predetermined value, depending on the driver, the vehicle may travel for a considerably long period while being left as it is. In this case, just waiting for maintenance and inspection at the sales point (dealer) of the vehicle or the like in a state where regeneration control is prohibited, the amount of collection will increase early. Then, when the amount of collection becomes extremely large, for example, when a large amount of air is introduced to the particulate filter by the fuel cut at the time of deceleration, the large amount of collected soot is burned rapidly to damage the particulate filter ( It may also cause the heat damage due to high heat).

  The present invention has been made in consideration of the above circumstances, and an object thereof is to collect the particulate filter while protecting the particulate filter even when the amount of soot collected by the particulate filter is increased. It is an object of the present invention to provide a control device of an engine which can suppress the increase of the engine speed or reduce the collection amount.

In order to achieve the above object, the following solutions are adopted in the present invention. That is, as described in claim 1,
A particulate filter disposed in the exhaust passage of the engine;
Control means for controlling the engine;
With a warning lamp,
Equipped with
The control means
Estimation control for estimating the amount of soot collected by the particulate filter;
Regeneration control for causing the particulate filter to be regenerated when the soot collection amount estimated by the estimation control becomes larger than a first predetermined value;
Fuel cut control that cuts off fuel when the engine decelerates,
When the collected amount of soot estimated by the estimation control becomes larger than a second predetermined value larger than the first predetermined value, the particulate matter flows into the particulate filter while allowing execution of the regeneration control. Exhaust gas amount increase control for increasing the amount of exhaust gas, and lighting control for lighting the warning lamp,
When the collection amount of soot estimated by the estimation control becomes larger than a third predetermined value larger than the second predetermined value, the execution of the regeneration control is prohibited and the warning lamp is turned on. Lighting control,
Is set to do,
It is done like that.

According to the solution method described above, when the amount of soot collected by the particulate filter becomes larger than the second predetermined value, the temperature rise of the particulate filter is suppressed by performing control to increase the exhaust gas amount. Alternatively, it can be lowered to protect it. In addition, even when the control to increase the amount of exhaust gas (protection control of the particulate filter) is performed, the execution of regeneration control is permitted, so that the increase in the amount collected by the particulate filter is suppressed or The amount of soot can be reduced, which leads to prolonging the time until maintenance or inspection of the particulate filter or eliminating the need for this maintenance and inspection, which is extremely preferable. . In addition to the above, the warning lamp is turned on when the trapped amount of soot becomes larger than the second predetermined value, so the driver is notified that a large amount of soot is collected by the particulate filter. Can be clearly recognized. As a result, in order to prompt maintenance and inspection at a vehicle selling point etc. at an early stage, or prompting the driver to perform feasible operation of the regeneration control, the increase in the burden is suppressed or the burden is reduced. In order to reduce the Furthermore, when the amount of soot collected becomes larger than the third predetermined value, the regeneration control is prohibited, so that the particulate filter can be prevented from being damaged by heat, and the warning lamp can be turned on. This makes it possible to go to the point of sale at the early stage of the vehicle and strongly encourage maintenance and inspection of the particulate filter.

  Preferred embodiments based on the above solution method are as described in claim 2 and the following claims.

  The idle rotational speed is corrected to rise by the exhaust gas amount increase control (corresponding to claim 2). In this case, the amount of exhaust gas can be increased by a simple method of increasing and correcting the idle speed.

The control means is adapted to perform fuel return control for resuming fuel supply when the engine speed is reduced to a predetermined return speed by the fuel cut control.
The return rotational speed is raised and corrected by the exhaust gas amount increase control.
(Claim 3). In this case, the amount of exhaust gas can be increased by a simple method of increasing and correcting the return rotation speed from the fuel cut.

  The exhaust gas amount increase control is performed on the condition that the temperature of the particulate filter is higher than a predetermined temperature (corresponding to claim 4). In this case, when the temperature of the particulate filter is lower than a predetermined temperature (for example, 800 to 850 ° C.), the amount of air in the exhaust gas, for example, due to fuel cut, even if the amount of collected soot is very large. Since the trapped soot is not burned rapidly even if the amount of hydrogen increases, it is preferable to prevent the exhaust gas amount increase control from being performed unnecessarily.

The control means prohibits the fuel cut control at the time of deceleration of the engine when the collected amount of soot estimated by the estimation control becomes larger than a third predetermined value larger than the second predetermined value. In addition, regenerative control is performed to compensate for the decrease in deceleration due to the prohibition of the fuel cut control (corresponding to claim 5). In this case, the particulate filter can be reliably prevented from being damaged by heat, and the decrease in deceleration can be compensated by the regeneration control.

  According to the present invention, even when the amount of soot collected by the particulate filter is increased, the increase in the amount of trapping can be suppressed or the amount of trapping can be reduced while protecting the particulate filter.

The figure which shows the example of whole system | strain of the engine to which this invention was applied. The figure which shows the correspondence of the amount of control collected by GPF, and the control content. The figure which shows the temperature fall of GPF by raising idle rotation speed. The figure which shows the correlation with idle rotation speed and GPF temperature. The figure which shows the fall of the GPF temperature by reducing the entrance temperature of GPF. The figure which shows correlation with GPF entrance temperature and GPF temperature. The figure which shows the example of a control system of this invention. The flowchart which shows the example of control of this invention.

  In FIG. 1, E is an engine (engine main body), and FIG. 1 is a cross-sectional view focusing on a certain cylinder. The engine E is an in-line four-cylinder four-cycle engine fueled by gasoline or the like.

  In FIG. 1, 1 is a cylinder, 2 is a cylinder head, and 3 is a piston slidably fitted in the cylinder 1. The piston 3 is interlocked with the crankshaft 4 via a connecting rod (not shown).

  A combustion chamber 5 is formed in the space above the piston 3 by the cylinder 1, the cylinder head 2 and the piston 3. An intake port 6 and an exhaust port 7 are opened in the combustion chamber 5. The intake port 6 is opened and closed by the intake valve 8, and the exhaust port 7 is opened and closed by the exhaust valve 9.

  The cylinder head 2 is provided with a spark plug 10, a fuel injection valve 11, and a pressure sensor 12 for detecting the pressure in the cylinder substantially at the center of the combustion chamber 5. In the embodiment, the engine E is a four-valve engine having two intake ports 6 (intake valves 8) and two exhaust ports 7 (exhaust valves 9) for one cylinder. The two intake valves 8 are spaced from each other in the axial direction of the crankshaft 4, and similarly, the two exhaust valves 9 are spaced from each other in the axial direction of the crankshaft 4.

  The ISG 14 is interlocked with the crankshaft 4 via the belt 13. The ISG 14 is a device that doubles as a starter motor and a generator (alternator or generator). That is, when the ignition switch is turned on, the engine E is started by driving the ISG 14. Further, during traveling, for example, at the time of deceleration, power generation is performed by the ISG 14 to perform regeneration (the regenerative energy is used to charge a battery, a capacitor, or the like, or supplied to various electric devices).

  An intake passage 20 is connected to the intake port 6. In the intake passage 20, an air cleaner 21, a throttle valve 22, a supercharger 23, and an intercooler 24 are disposed sequentially from the upstream side to the downstream side. Reference numeral 25 denotes a motor for driving the supercharger 23. A bypass passage 26 is connected to the intake passage 20. The upstream end of the bypass passage 26 is open to the intake passage 20 between the throttle valve 22 and the supercharger 23. Further, the downstream end of the bypass passage 26 is opened to the intake passage 20 at the downstream side of the intercooler 24. A bypass valve 27 is disposed in the bypass passage 26.

  An exhaust passage 30 is connected to the exhaust port 7. The upstream end of the exhaust passage 30 is constituted by an exhaust manifold 31 common to the respective cylinders. In the exhaust passage 30, a small capacity first three-way catalyst 32, a GPF (particulate filter) 33, and a large capacity second three-way catalyst 34 are disposed sequentially from the upstream side toward the downstream side. . The GPF 33 collects particulates in the exhaust gas. Then, the amount of soot deposited on the GPF 33 is detected based on the detection signal from the pressure sensor 35 that detects the pressure difference between the upstream side and the downstream side of the GPF 33.

  The intake passage 20 and the exhaust passage 30 are connected via an EGR passage 40. The upstream end of the EGR passage 40 is open to the exhaust passage 30 between the GPF 33 and the second three-way catalyst 34. The downstream end of the EGR passage 40 is opened to the upstream side of the bypass valve 27 in the bypass passage 26. Then, an EGR cooler 41 and an EGR valve 42 are disposed in the EGR passage 40 sequentially from the upstream side to the downstream side.

  The engine E as described above uses gasoline as fuel and has an extremely lean air-fuel ratio (for example, an air-fuel ratio in a predetermined operating range (for example, a range where an accelerator opening is less than a predetermined opening and an engine speed is less than a predetermined engine speed) Is about 30) and compression self-ignition may be performed (in some cases, compression self-ignition may be promoted using the fire species generated by the ignition of the spark plug 10). And, except for the above-mentioned predetermined operation range, combustion is carried out by the spark ignition system by ignition of the spark plug 10 (the air-fuel ratio is mainly in the vicinity of the theoretical air-fuel ratio) as in a normal gasoline engine. For this reason, the geometric compression ratio of the engine E is set to be considerably higher than that of a normal gasoline engine (for example, the geometric compression ratio is 18 or more and the effective compression ratio is 16 or more).

  The supercharger 23 is operated to secure a large amount of air required when performing the above-described compression auto-ignition, and at this time, the bypass valve 27 is closed. On the other hand, in the operation region where ignition is performed by spark ignition, the operation of the supercharger 23 is stopped and the bypass valve 27 is opened.

  Here, the GPF 33 needs to be regenerated at an appropriate timing because the amount of collected soot increases by continuing the operation. The regeneration of the GPF 33 is performed by burning the soot with the GPF 33 by the post injection of fuel and the retard of the fuel injection timing. The regeneration of the GPF 33 is performed when the engine is in a predetermined operation range (for example, steady traveling except during acceleration, deceleration, the accelerator opening is equal to or greater than the predetermined opening, and the engine rotational speed is predetermined). When all the conditions of being equal to or higher than the rotation speed are satisfied).

  Next, with reference to FIG. 2, an outline of control contents according to the amount of collected soot (the amount of deposition) in the GPF 33 will be described. First, three threshold values of SLM1, SLM2, and SLM3 are set as the amount of collection of soot on the GPF 33 in ascending order from the smaller one (SLM1 <SLM2 <SLM3).

  When the collected amount of soot is equal to or less than the SLM 1, the collected amount is small, and the regeneration of the GPF 33 is not performed (a state where the collected amount of soot in the GPF 33 increases according to traveling).

  When the amount of soot collected by the GPF 33 is larger than that of the SLM 1 and smaller than or equal to the SLM 2, regeneration of the GPF 33 is performed (execution of post injection or retarded injection in normal reproduction).

  When the amount of soot collected by the GPF 33 is larger than that of the SLM 2 and not more than the SLM 3, regeneration of the GPF 33 is performed while performing protection control to prevent thermal damage to the GPF 33. This protection control can be roughly classified into the following first and second two methods as appropriate. In this case, the warning lamp S4 is turned on because the driver is in a situation where the amount of soot collected by the GPF 33 is too large. The lighting of the warning lamp S4 prompts the driver to drive to become the regeneration execution area of the GPF 33, and visit the vehicle selling point (dealer) at an early stage to receive maintenance and inspection of the GPF 33. Prompted.

  First, protection control of the GPF 33 is to increase the flow rate of exhaust gas flowing into the GPF 33 (to release the temperature of the GPF 33 into the exhaust gas). The exhaust gas flow rate can be increased, for example, by increasing the return rotation speed at the time of fuel cut or by increasing the idle rotation speed.

In FIG. 3, fuel cut is started from a state where engine speed is increased by running after warm-up operation (time t1), fuel cut is canceled at time t2, and then idle speed is restored. Show the process of The temperature of the GPF 33 (main part = filter part) is lowered from T11 to T12 by increasing the number of revolutions after returning from the fuel cut or increasing the number of idle revolutions, thereby protecting the GPF 33. FIG. 4 shows the relationship between the idle speed and the maximum temperature of the GPF 33, and shows that the temperature of the GPF 33 is greatly reduced by increasing the idle speed.

  Second, protection control of the GPF 33 is control to suppress the temperature rise of the GPF 33 by output control of the engine. The output control of the engine can be performed, for example, by reducing the engine torque than the target torque or enriching the air-fuel ratio.

  In FIG. 5, the fuel cut is started from the state where the engine speed is increased by running after the warm-up operation (time t1), the fuel cut is canceled at time t2, and then the idle speed is restored. Show the process of By reducing the engine torque from the target torque or enriching the air-fuel ratio, the inlet temperature T1 of the GPF 33 decreases as indicated by T2, and accordingly, the temperature of (the main body portion = filter portion) of the GPF 33 decreases. The protection from GPF 33 is achieved by lowering from T11 to T12. FIG. 6 shows the relationship between the inlet temperature of GPF 33 and the maximum temperature of (the main body of) GPF 33, and shows that the temperature of GPF 33 is greatly reduced by decreasing the inlet temperature of GPF 33.

  When the amount of soot collected by the GPF 33 is larger than that of the SLM 3, regeneration of the GPF 33 is prohibited and fuel cut performed at the time of deceleration is prohibited (preventing a situation where the GPF 33 is thermally damaged) . In addition, when the fuel cut is prohibited at the time of deceleration, regeneration by causing the ISG 14 to function as a generator is performed to secure a necessary deceleration. Also, the warning lamp S4 is on, but the regeneration control of the GPF 33 is prohibited, and the amount of soot collected is increasing, so we go to the vehicle selling point (dealer) earlier to maintain and inspect the GPF 33 The warning lamp S4 can be lighted in a blinking state so as to strongly prompt the user to receive the warning.

  FIG. 7 shows an example of a control system for performing the control described above. In the figure, U is a controller configured using a microcomputer. In addition to the signal from the pressure sensor 35 for detecting the amount of soot collected by the GPF 33 described above, the controller U receives signals from various sensors S1 to S3. S1 is a rotational speed sensor that detects an engine rotational speed. S2 is an accelerator opening sensor that detects the accelerator opening. S3 is a temperature sensor that detects the inlet temperature of the GPF 33 (in the embodiment, the temperature immediately upstream of the first three-way catalyst 32). The controller U controls the warning lamp S4 in addition to controlling the fuel injection valve 11 and the ISG 14.

  Next, control contents of the controller U will be described with reference to FIG. In the following description, Q indicates a step. First, after the signals from various sensors and the like are read in Q1, the target torque is calculated in Q2. The target torque is basically set using the engine speed and the accelerator opening as parameters, and is further corrected by the intake air temperature, the engine coolant temperature, and the like. In addition, since the method itself of calculating (setting) a target torque is variously proposed conventionally, the description beyond this is abbreviate | omitted.

  In Q3, the amount of soot collected by the GPF 33 is estimated based on the signal from the pressure sensor 35. After Q3, in Q4, it is determined whether the soot collection amount estimated in Q3 is larger than a predetermined value SLM3. When the determination of Q4 is NO, it is determined in Q5 whether the soot collection amount is larger than SML1. When the determination of Q5 is NO, fuel injection control is performed in Q6 according to the target torque. The target torque from Q5 to Q6 is the target torque set in Q2, and the target torque is not reduced.

  If YES in the determination of Q5, regeneration of the GPF 33 is executed in Q7 (execution of post injection or retard injection). Thereafter, in Q8, it is determined whether the amount of collected soot is larger or larger than SML2. If the result of the determination of Q8 is NO, then the process shifts to Q6.

  When the determination of Q8 is YES, the warning lamp S4 is turned on in Q9. Thereafter, in Q10, it is determined whether or not acceleration is in progress. If YES in the determination of Q10, the target torque set in Q2 is corrected in Q11 so as to decrease by a predetermined amount. After this, it shifts to Q6. The decrease of the target torque in Q11 suppresses the increase of (the inlet temperature of) the GPF 33, thereby protecting the GPF 33. The process from Q11 to Q6 corresponds to the state in which the inlet temperature of GPF 33 is reduced from T1 to T2 in FIG. 5 (as a result, the state in which the temperature of GPF 33 is reduced from T11 to T12) doing).

  When the determination of Q10 is NO, it is determined in Q12 whether it is time to cut the fuel at the time of deceleration. When the determination of Q12 is NO, the process is shifted to Q6 (the target torque set in Q2 is executed in Q6).

  If the determination of Q12 is YES, fuel cut is performed in Q13. After that, in Q14, the return rotational speed from the fuel cut is corrected to a large rotational speed which is higher by a predetermined amount than that at the normal time. Thereafter, in Q15, it is determined whether or not the engine speed has decreased to the return speed corrected to be increased in Q14. If NO in the determination of Q15, the process returns to Q13.

  If the determination in Q15 is YES, fuel injection is resumed in Q16. After that, in Q17, the idle speed is corrected to rise. The process from Q12 to Q17 corresponds to the state in which the engine speed is corrected to increase from N1 to N2 in FIG. 3 (as a result, it corresponds to the state in which the temperature of GPF 33 decreases from T11 to T12) doing).

  If YES in the determination of Q4, the warning lamp S4 is turned on in Q18, and the reproduction of the GPF 33 is prohibited. It is preferable to turn on the warning lamp S4 in Q18 so as to give a stronger warning than the warning by turning on Q9. After Q18, fuel cut at deceleration is prohibited in Q19. In addition, since fuel cut is not performed at the time of deceleration in Q20, regeneration by ISG 14 is performed to compensate for the decrease in deceleration.

  Although the embodiments have been described above, the present invention is not limited to the embodiments, and appropriate modifications can be made within the scope of the claims. For example, in Q11 of FIG. 8, it is also possible to make a correction to make the air-fuel ratio rich. In Q20 of FIG. 8, instead of or in addition to the fuel cut prohibition at the time of deceleration, the air fuel ratio leaning (especially the extreme return for compression self-ignition) is prohibited and the air fuel ratio is set to λ = 1, for example. Alternatively, it may be set in the vicinity (performs ordinary spark-ignition ignition). The engine may perform only ignition by spark ignition without performing compression self-ignition. The process of Q14 and Q17 (exhaust gas amount increase control) or the process of Q19 and 20 may be executed on condition that the GPF 33 (particulate filter) is at a predetermined temperature or higher. The engine may be a diesel engine (particulate filter is DPF). Of course, the object of the present invention is not limited to what is explicitly stated, but implicitly also includes providing what is substantially preferred or expressed as an advantage.

  The present invention is suitably applied to a vehicle having a particulate filter.

E: Engine U: Controller S1: Sensor (engine speed)
S2: Sensor (accelerator opening)
S3: Sensor (GPF entrance temperature)
S4: warning lamp 11: fuel injection valve 14: ISG (starter motor and generator)
30: Exhaust passage 33: GPF (particulate filter)
35: Pressure sensor (for detecting the amount of soot collected)

Claims (5)

A particulate filter disposed in the exhaust passage of the engine;
Control means for controlling the engine;
Equipped with
The control means
Estimation control for estimating the amount of soot collected by the particulate filter;
Regeneration control that causes the particulate filter to be regenerated when the soot collection amount estimated by the estimation means becomes larger than a first predetermined value;
Fuel cut control that cuts off fuel when the engine decelerates,
When the collected amount of soot estimated by the estimation means becomes larger than a second predetermined value larger than the first predetermined value, the particulate matter flows into the particulate filter while permitting execution of the regeneration control. Exhaust gas amount increase control to increase the amount of exhaust gas
Is set to do,
An engine control device characterized by In claim 1,
An engine control system characterized in that an idle speed is corrected to rise by the exhaust gas amount increase control. In claim 1 or claim 2,
The control means is adapted to perform fuel return control for resuming fuel supply when the engine speed is reduced to a predetermined return speed by the fuel cut control.
The return rotational speed is raised and corrected by the exhaust gas amount increase control.
An engine control device characterized by In any one of claims 1 to 3,
The engine control device according to claim 1, wherein the exhaust gas amount increase control is executed on the condition that the temperature of the particulate filter is higher than a predetermined temperature. In any one of claims 1 to 4,
Equipped with a warning lamp
The control means performs lighting control to light the warning lamp when the collected amount of soot estimated by the estimation means becomes larger than the second predetermined value.
An engine control device characterized by

Images