JP4803198B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection control device in an internal combustion engine provided with fuel addition means for adding fuel to an aftertreatment device that purifies unclean substances contained in exhaust gas.

  2. Description of the Related Art An exhaust gas purification device that includes a fuel addition means in addition to a post-treatment device that purifies exhaust gas in an engine exhaust passage has been known. The purpose of adding the fuel is utilization as a reducing agent, increase in exhaust gas temperature, and the like, and examples thereof are disclosed in Patent Document 1. Patent Document 1 discloses an exhaust gas purification device in which a particulate filter carrying a NOx (nitrogen oxide) storage reduction catalyst is disposed in an exhaust gas passage of an internal combustion engine. The NOx occlusion reduction catalyst occludes NOx when the air-fuel ratio of the exhaust gas is lean, and occludes when the air-fuel ratio in the exhaust gas is small and a reducing agent such as HC or CO exists in the exhaust gas. Releases and reduces and purifies NOx. The NOx occlusion reduction catalyst disposed in the exhaust passage occludes NOx in the exhaust gas when the air-fuel ratio of the exhaust gas is lean. However, the NOx occlusion efficiency of the NOx occlusion reduction catalyst decreases with NOx occlusion. Therefore, when the NOx occlusion efficiency is lowered or before it is lowered, a reducing agent (fuel) is added upstream of the NOx catalyst to reduce and purify the NOx occluded in the NOx catalyst.

  Further, if particulate matter (PM) collected by the particulate filter accumulates in a laminated form on the particulate filter, it is difficult to ignite and burn the accumulated PM at a normal exhaust gas temperature. Become. Therefore, an oxidation catalyst is arranged upstream of the particulate filter, fuel is added from the addition nozzle to the exhaust passage, the temperature of the exhaust gas is increased by the reaction of the fuel on the oxidation catalyst, and the catalyst is deposited in a stacked manner on the particulate filter. The particulate filter is ignited and burned to regenerate the particulate filter.

  However, when the temperature at the nozzle tip of the additive nozzle becomes high, the fuel remaining in the injection hole at the nozzle tip solidifies, or black smoke in the exhaust gas adheres to the nozzle at the nozzle tip. Or the inside of the injection hole at the nozzle tip may be clogged.

In Patent Document 1, the exhaust gas temperature in the vicinity of the addition nozzle is detected, and when the detected exhaust gas temperature is equal to or higher than a predetermined temperature, the exhaust gas flow rate in the vicinity of the addition nozzle is reduced to prevent clogging in the addition nozzle. Is disclosed.
JP 2004-68761 A

  The clogging prevention measures disclosed in Patent Document 1 require a detector for detecting the exhaust gas temperature in the vicinity of the addition nozzle, and an exhaust gas flow rate switching means to reduce the exhaust gas flow rate in the vicinity of the addition nozzle. Such a configuration leads to a complicated and long path for the exhaust passage. Therefore, the exhaust gas temperature near the catalyst is lowered, and the purification performance of the catalyst is lowered. If the amount of fuel added from the addition nozzle is increased in order to avoid a decrease in the exhaust gas temperature in the vicinity of the catalyst, the fuel consumption performance deteriorates.

Further, the complicated and long exhaust passage causes an increase in exhaust resistance, resulting in a decrease in output performance.
An object of the present invention is to provide a fuel injection control device in an internal combustion engine that can prevent a clogging of an addition nozzle and suppress a fuel consumption while avoiding a decrease in output performance.

  Therefore, the present invention provides a plurality of cylinders that accommodate pistons, a fuel supply means for supplying fuel to the plurality of cylinders, and a fuel supply control that controls fuel supply to the plurality of cylinders by the fuel supply means. Means, an exhaust passage that introduces exhaust gas discharged from each cylinder, and an exhaust passage that is introduced into a post-treatment device that purifies an unclean substance after joining, and an addition target tributary portion upstream from the joining portion of the exhaust passage, Fuel addition means having an addition nozzle for adding fuel to exhaust gas, clog prevention control means for controlling clog prevention injection for injecting the fuel from the addition nozzle to prevent clogging in the addition nozzle, and operation The present invention is directed to a fuel injection control device in an internal combustion engine that includes an operation state detection unit that detects a state. In the invention of claim 1, the fuel supply control unit includes the operation state detection unit. The fuel supply amount in a specific cylinder that discharges exhaust gas to the addition target tributary portion is reduced from the normal supply amount per cylinder in at least a part of the entire range of operating states detected by the means, and other cylinders Increase / decrease control is performed to increase the fuel supply amount at the above-mentioned normal supply amount.

  The control for reducing the fuel supply amount in the specific cylinder that discharges the exhaust gas to the addition target tributary portion from the normal supply amount reduces the temperature of the exhaust gas discharged from the specific cylinder and reduces the exhaust amount in the addition nozzle. Delay clogging. Therefore, the amount of fuel consumed by the clogging prevention injection can be reduced, and the amount of fuel consumed can be suppressed. Control for increasing the fuel supply amount of the other cylinders from the normal supply amount avoids a decrease in output performance.

In a preferred example, the fuel supply control means performs the increase / decrease control when the operation state detected by the operation state detection means is in a high temperature region.
In a situation where the operating state is in a high temperature region, the exhaust gas temperature is high and the exhaust gas discharge flow rate is large, so that the clogging of the addition nozzle is fast. Such a situation is particularly suitable for application of control in which the fuel supply amount in the cylinder that discharges the exhaust gas to the addition target tributary portion is less than the normal supply amount.

  In a preferred example, the fuel supply control unit gradually changes the fuel supply amount in the specific cylinder from the normal supply amount as the operation state detected by the operation state detection unit shifts from the low temperature region to the high temperature region. And the first gradual change control for gradually increasing the fuel supply amount in the other cylinders from the normal supply amount, and the fuel supply control means detects the operating state detected by the operating state detecting means. As the fuel temperature shifts from the high temperature region to the low temperature region, the fuel supply amount in the specific cylinder is gradually increased to return to the normal supply amount, and the fuel supply amount in the other cylinders is gradually decreased. Second gradual change control for returning to the normal supply amount is performed.

The first gradual change control and the second gradual change control are preferable in order to bring about a smooth change in the engine speed.
In a preferred example, the fuel supply control means performs the increase / decrease control in the entire region of the operation state detected by the operation state detection means.

The increase / decrease control in the entire region of the operating state is particularly preferable for suppressing the fuel consumption.
In a preferred example, when the operating state detected by the operating state detecting unit is in a low temperature region and the fuel supply control unit adds fuel to the aftertreatment device, the fuel supply amount in the specific cylinder is reduced. The control for reducing the normal supply amount is stopped.

  If the fuel supply amount in the specific cylinder is reduced from the normal supply amount when the operation state is in the low temperature region, the temperature of the exhaust gas discharged from the specific cylinder becomes low. Therefore, the fuel injected from the addition nozzle for adding the fuel to the post-processing device is difficult to atomize. Stopping the control for reducing the fuel supply amount in the specific cylinder from the normal supply amount when the operation state is in the low temperature region is preferable in terms of atomization of the fuel injected from the addition nozzle.

  In a preferred example, the fuel supply control means sets the fuel supply amount in the specific cylinder to the normal supply amount in a part of the operation state other than the operation state in which control for reducing the fuel supply amount in the specific cylinder is performed. While maintaining, control is performed to increase the fuel supply amount in the other cylinders than the normal supply amount.

  Such control is suitable for application in an operating state in which it is required to improve output performance.

  The present invention has an excellent effect of preventing a decrease in output performance while preventing clogging in the addition nozzle and suppressing fuel consumption.

Hereinafter, a first embodiment in which the present invention is embodied in a four-cylinder diesel engine will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1 (a), the diesel engine 10 (internal combustion engine) includes a plurality of cylinders 11, 12, 13, and 14 that accommodate pistons (not shown). A combustion chamber is defined in 14. Fuel injection nozzles 16, 17, 18, and 19 are attached to the cylinder head 15 for each of the cylinders 11, 12, 13, and 14. The fuel (light oil) is supplied to the fuel injection nozzles 16, 17, 18, 19 via the fuel pump 20 and the common rail 21, and the fuel injection nozzles 16, 17, 18, 19 are connected to the cylinders 11, 12, 13, 19. Fuel is injected into the combustion chamber in 14. The fuel pump 20 and the fuel injection nozzles 16, 17, 18, 19 constitute fuel supply means for supplying fuel to the cylinders 11-14.

  An intake manifold 22 is connected to the cylinder head 15. An intake pipe 23 is connected to the intake manifold 22, and an air cleaner 24 is connected to the intake pipe 23. A compressor unit 251 of the supercharger 25 is provided in the middle of the intake pipe 23. The supercharger 25 is a known variable nozzle turbocharger that is operated by an exhaust gas flow.

  A throttle valve 26 is provided in the middle of the intake pipe 23. The throttle valve 26 is for adjusting the flow rate of air drawn into the intake pipe 23 via the air cleaner 24. The opening degree of the throttle valve 26 is changed by a stepping motor 27. The stepping motor 27 is controlled by the control computer C.

  An exhaust manifold 28 is connected to the cylinder head 15. An exhaust pipe 29 is connected to the exhaust manifold 28. A post-treatment device 30 is provided on the exhaust pipe 29. As the aftertreatment device 30, an NOx storage reduction catalyst or a selective reduction NOx catalyst is used. Exhaust gas discharged from the cylinders 11, 12, 13, and 14 is discharged to the atmosphere via the exhaust manifold 28, the turbine unit 252 of the supercharger 25, the exhaust pipe 29, and the aftertreatment device 30.

  An intake port 31 and exhaust ports 32, 32A are formed in the cylinder head 15 so as to communicate with the combustion chamber. A branch pipe portion 33 of the intake manifold 22 is connected to the intake port 31, and branch pipe portions 34, 34A of the exhaust manifold 28 are connected to the exhaust ports 32, 32A. The exhaust ports 32, 32 A, the branch pipe portions 34, 34 A, and the exhaust pipe 29 constitute an exhaust passage that joins exhaust gases discharged from the cylinders 11, 12, 13, 14 and introduces them into the aftertreatment device 30. The exhaust ports 32, 32 </ b> A and the branch pipe portions 34, 34 </ b> A constitute a tributary portion upstream from the merging portion 281 of the exhaust manifold 28.

  A crank angle detector 35 and an accelerator sensor 36 are signal-connected to the control computer C. The crank angle detector 35 detects a rotation angle (crank angle) of a crankshaft (not shown). The crank angle information detected by the crank angle detector 35 is sent to the control computer C. The control computer C calculates the engine speed N based on the crank angle information detected by the crank angle detector 35.

  The accelerator sensor 36 detects the amount of depression of an accelerator pedal (not shown). The depression amount detection information detected by the accelerator sensor 36 is sent to the control computer C. The control computer C calculates the fuel injection amount at the fuel injection nozzles 16, 17, 18, 19 by performing correction based on the depression amount detection information and the engine speed information, and if necessary, based on the water temperature, the outside air temperature, etc. Control. In the present embodiment, the control computer C regards the calculated fuel injection amount as the engine load F.

  The control computer C, the crank angle detector 35, and the accelerator sensor 36 constitute an operation state detection unit that detects an operation state represented by the engine speed N and the engine load F.

Further, the control computer C controls the rotational position of the stepping motor 27 by designating the opening degree of the throttle valve 26 based on the grasped engine load F and the engine speed N.
The cylinder head 15 is provided with an addition nozzle 37. The addition nozzle 37 is provided so that the injection hole at the tip thereof faces the exhaust port 32 </ b> A of the cylinder 11. An addition pump 38 is connected to the addition nozzle 37. The addition pump 38 supplies fuel to the addition nozzle 37. The addition nozzle 37 injects the supplied fuel into the exhaust port 32 </ b> A of the cylinder 11. The operation of the addition pump 38 is controlled by the control computer C. The addition pump 38 and the addition nozzle 37 constitute fuel addition means for adding fuel to the post-processing device 30.

  A control computer C that controls the injection of the fuel injection nozzles 16, 17, 18, 19 controls the operation of the addition pump 38. The control computer C estimates the operation timing of the addition pump 38 for adding fuel to the aftertreatment device 30 based on the integration of the operation state represented by the engine load F and the engine speed N. The control computer C also clogs the addition nozzle 37 (solidified fuel and exhaust gas in the injection hole at the tip of the nozzle) based on the accumulated operating state represented by the engine load F and the engine speed N. Grasping the amount of black smoke inside.

  A waveform E1 in the graph of FIG. 1B2 shows an example of a change in the amount of clogging in the addition nozzle 37. The clogging amount K indicates a value set as a limit value. When the clogging amount determined based on the engine load F and the engine speed N reaches the clogging amount K, the control computer C causes the addition pump 38 to be turned on for a predetermined time. A predetermined amount of fuel is injected from the addition nozzle 37 by operating. This injection removes a part of the deposit in the injection hole of the addition nozzle 37 and suppresses clogging in the addition nozzle 37.

  The control computer C performs fuel injection control based on the fuel injection control program shown in the flowchart of FIG. Hereinafter, the fuel injection control of the diesel engine 10 will be described based on the flowchart of FIG.

  The control computer C waits for an operation start signal to be input (step S1). Along with the input of the operation start signal (YES in step S1), the control computer C controls the fuel injection amount in the cylinder 11 to be lower than the average fuel injection amount Go (normal supply amount) in all the cylinders 11 to 14, and The fuel injection amount in the cylinders 12 to 14 is controlled to be increased from the average fuel injection amount Go (normal supply amount) (step S2). In the control in step S2, the fuel injection amount from the fuel injection nozzle 16 corresponding to the cylinder 11 is reduced from the average fuel injection amount Go, and the fuel injection from the fuel injection nozzles 17 to 19 corresponding to the cylinders 12 to 14 is performed. This is an increase / decrease control for increasing the amount from the average fuel injection amount Go. This increase / decrease control is performed in the entire region of the operating state represented by the engine speed and the engine load.

  A line D1 in the graph of FIG. 1 (b1) indicates the fuel injection amount G1 from the fuel injection nozzle 16, and a line D2 indicates the fuel injection amount G1 from the fuel injection nozzles 17-19. A line Do indicates the average fuel injection amount Go in all the cylinders 11 to 14. In the present embodiment, the increase in fuel injection amount (G2-Go) in the three fuel injection nozzles 17 to 19 other than the cylinder 11 is 1 / of the decrease in fuel injection amount in the fuel injection nozzle 16 (Go-G1). Tripled.

  After the start of operation, the control computer C determines whether or not an operation stop signal has been input (step S3). When the operation stop signal is input (YES in step S3), the control computer C stops the fuel injection amount control (step S4).

  The control computer C is fuel supply control means for controlling fuel supply to the cylinders 11 to 14 by the fuel supply means. The control computer C is clogging prevention control means for controlling clogging prevention injection for injecting fuel from the addition nozzle 37 in order to prevent clogging in the addition nozzle 37.

In the first embodiment, the following effects can be obtained.
(1) A line Do in the graph of FIG. 1 (c1) indicates the fuel injection amount Go in each cylinder of a conventional four-cylinder diesel engine. A waveform Eo in the graph of FIG. 1 (c2) shows an example of a change in the clogging amount in the addition nozzle in the conventional four-cylinder diesel engine.

  In this embodiment, the fuel supply amount Go (normal supply per cylinder) is the average fuel supply amount in the cylinder 11 (specific cylinder) that discharges exhaust gas to the exhaust port 32A and the branch pipe portion 34A that constitute the addition target branch. The amount). Therefore, the exhaust gas temperature in the branch pipe portion 34A is lower than in the conventional case where the fuel supply amount in the cylinder 11 becomes the average fuel injection amount Go. Moreover, the amount of exhaust gas discharged from the cylinder 11 to the branch pipe portion 34A is smaller than in the conventional case where the fuel supply amount in the cylinder 11 becomes the average fuel injection amount Go. The reduction of the exhaust gas temperature in the branch pipe portion 34A brings about the reduction of the solidification of the fuel in the addition nozzle 37, and the reduction of the amount of exhaust gas discharged from the cylinder 11 to the branch pipe portion 34A results in the black smoke in the exhaust gas. Results in a reduction in the amount of deposits in the addition nozzle 37.

  That is, the reduction control for reducing the fuel supply amount in the cylinder 11 (specific cylinder) from the average fuel injection amount Go (normal supply amount per cylinder) delays the progress of clogging in the addition nozzle 37. As a result, as indicated by the waveform E1 in FIG. 1B2, the interval t1 at which the clogging amount at the addition nozzle 37 reaches the clogging amount K is longer than the interval to indicated by the waveform Eo shown in FIG. The fact that the interval t1 is longer than the interval to means that the amount of fuel injected from the addition nozzle 37 is reduced in order to prevent clogging in the addition nozzle 37.

  (2) In the control to increase the fuel injection amount in the cylinders 12 to 14 from the average fuel injection amount Go, the increase amount (G2-Go) of the fuel injection amount in the three fuel injection nozzles 17 to 19 other than the cylinder 11 is The fuel injection amount at the fuel injection nozzle 16 is reduced to 1/3 times the amount of reduction (Go-G1). Therefore, the output decrease due to the fuel decrease in the cylinder 11 is compensated by the fuel increase in the other cylinders 12 to 14, and the output performance does not decrease.

(3) In this embodiment, since increase / decrease control is performed in the entire region of the operating state, the effect of suppressing fuel consumption is the highest.
Next, a second embodiment of FIGS. 3 and 4 will be described. The apparatus configuration is the same as that of the first embodiment, and the same components are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 4 is a flowchart showing the fuel injection control program. The same steps as those in the flowchart of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 3 shows the operating state represented by the engine speed N and the engine load F. A region L indicates a low temperature region that is set assuming that the exhaust gas temperature is lower than the reference temperature among all the regions indicating the operating state, and a region H indicates that the exhaust gas temperature is the reference temperature among all the regions indicating the operating state. Indicates a high temperature region that is set assuming that the temperature is higher. The reference temperature is set in order to define the speed of clogging progress. In the region L lower than the reference temperature, it is considered that clogging progresses in the addition nozzle 37 and is slower than the reference temperature. In the high temperature region H, it is considered that the progress of clogging in the addition nozzle 37 is fast. Hereinafter, an operation state represented by a set (N, F) of the engine speed N and the engine load F is referred to as an operation state (N, F).

Hereinafter, the fuel injection control of the diesel engine 10 will be described based on the flowchart of FIG.
After inputting the operation start signal, the control computer C determines whether or not the operation state (N, F) is in the low temperature region L (step S5). When the operating state (N, F) is in the low temperature region L (YES in step S5), the control computer C performs normal injection control for controlling the fuel injection amount in the cylinders 11 to 14 to the normal injection amount (step S6). . In the normal injection control, the fuel injection amounts in the fuel injection nozzles 16 to 19 are all the fuel injection amount Go.

  When performing normal injection control, the control computer C determines whether or not an operation stop signal is input (step S31). When the operation stop signal is not input (NO in step S31), the control computer C determines whether or not the operation state (N, F) is in the low temperature region L (step S7). If the operating state (N, F) is in the low temperature region L (YES in step S7), the control computer C proceeds to step S6.

  When the operation state (N, F) is not in the low temperature region L (NO in step S7), that is, when the operation state (N, F) is shifted from the low temperature region L to the high temperature region H, the control computer C performs the increase / decrease control. Perform (step S2).

  When the increase / decrease control is performed, the control computer C determines whether or not an operation stop signal is input (step S32). When the operation stop signal is not input (NO in step S32), the control computer C determines whether or not the operation state (N, F) is in the low temperature region L (step S8). If the operating state (N, F) is not in the low temperature region L (NO in step S8), the control computer C proceeds to step S2. When the operation state (N, F) is in the low temperature region L (YES in step S8), that is, when the operation state (N, F) is shifted from the high temperature region H to the low temperature region L, the control computer C proceeds to step S6. Transition.

  In the situation where the operation state is in the high temperature region H, the exhaust gas temperature is high and the exhaust gas discharge flow rate is large, so that the clogging of the addition nozzle is fast. The control for reducing the fuel supply amount in the cylinder 11 that discharges the exhaust gas to the branch pipe portion 34A to be added is smaller than the normal injection amount Go, and is particularly suitable for application in a situation where the operating state is in a high temperature region.

  Next, a third embodiment of FIG. 5 will be described. The apparatus configuration is the same as in the first and second embodiments, and the same components are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 5 is a flowchart showing the fuel injection control program. The same steps as those in the flowchart in the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the third embodiment, the first gradual change control (step S9) is performed at the time of transition from step S7 to step S2, and the second gradual change control (step S10) at the time of transition from step S8 to step S6. ) Is performed. In the first gradual change control in step S9, when the operating state shifts from the low temperature region L to the high temperature region H, the fuel injection amount in the cylinder 11 is gradually decreased from the normal injection amount Go, and the cylinders 12 to 14 In this control, the fuel injection amount is gradually increased from the normal injection amount Go. In the second gradual change control in step S10, when the operating state shifts from the high temperature region H to the low temperature region L, the fuel injection amount in the cylinder 11 is gradually increased to return to the normal injection amount Go, and the cylinder 12 In this control, the fuel injection amount at ˜14 is gradually reduced and returned to the normal injection amount Go. For example, the gradual change of the fuel injection amount in the cylinder 11 is performed by 1/10 of the amount of decrease (Go-G1) every rotation of the engine, and the gradual change of the fuel injection amount in the cylinders 12 to 14 is For each rotation, 1/10 of the increase (G2-Go) is performed.

The gradual change control in steps S9 and S10 is preferable in order to bring about a smooth change in the engine speed.
Next, a fourth embodiment shown in FIGS. 6 to 8 will be described. The apparatus configuration is the same as that of the second embodiment, and the same components are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 8 is a flowchart showing the fuel injection control program. The same steps as those in the flowchart in the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 6 shows the operating state (N, F) represented by the engine speed N and the engine load F. The region M is set as a region where high output and high load and high output performance are required.

  In the fourth embodiment, if NO in step S5 (when the operating state is the high temperature region H), the control computer C determines whether or not the operating state (N, F) is in the region M. (Step S11). If the operating state (N, F) is not in region M (NO in step S11), control computer C proceeds to step S2. When the operating state (N, F) is in the region M (YES in step S11), the control computer C performs normal control to set the fuel injection amount in the cylinder 11 to the normal injection amount Go, and the fuel in the cylinders 12-14. Increase control for increasing the injection amount from the normal injection amount Go is performed.

  When performing the increase control, the control computer C determines whether or not an operation stop signal is input (step S33). When the operation stop signal is not input (NO in step S33), the control computer C proceeds to step S11.

  A line Do in the graph of FIG. 7 indicates the fuel injection amount Go from the fuel injection nozzle 16, and a line D3 indicates the fuel injection amount G3 from the fuel injection nozzles 17-19. A line Do indicates the average fuel injection amount Go in all the cylinders 11 to 14. In the present embodiment, the increase in fuel injection amount (G3-Go) in the three fuel injection nozzles 17 to 19 other than the cylinder 11 is set according to the operation state (N, F) in the region M.

Such control is suitable for application in an operation state (region M) where output performance is required to be improved.
Next, a fifth embodiment of FIG. 9 will be described. The apparatus configuration is the same as that of the first embodiment, and the same components are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 9 is a flowchart showing a fuel injection control program. The same steps as those in the flowchart in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  When the operation start signal is input (YES in step S1), the control computer C determines whether or not the operation state (N, F) is in the region Le (step S5e). The region Le is set as a low temperature region in a low rotation-low load region. When the operating state (N, F) is not in the low temperature region Le (NO in step S5e), the control computer C controls the fuel injection amount in the cylinder 11 to be less than the average fuel injection amount Go, and the cylinders 12-14. Increase / decrease control is performed to increase the fuel injection amount at the amount greater than the average fuel injection amount Go (step S2).

  When the operating state (N, F) is in the low temperature region Le (YES in step S5e), the control computer C determines whether it is time to add fuel to the post-processing device 30 (step 13). If it is not time to add fuel to the aftertreatment device 30 (NO in step S13), the control computer C proceeds to step S2.

  When it is time to add fuel to the aftertreatment device 30 (YES in step S13), the control computer C performs normal injection control for controlling the fuel injection amount in the cylinders 11 to 14 to the normal injection amount (step S6). ). That is, when the operating state (N, F) is in the low temperature region Le and the fuel is added to the post-processing device 30, the control computer C stops the control for reducing the fuel supply amount in the cylinder 11 below the normal injection amount Go. To do.

  When performing the normal injection control, the control computer C determines whether or not an operation stop signal has been input (step S34). When the operation stop signal is not input (NO in step S34), the control computer C proceeds to step S5e.

  When fuel (light oil) that is not sufficiently vaporized is adsorbed directly to the active site of the catalyst, the catalytic activity is significantly reduced. If the fuel is supplied to the catalyst without being sufficiently vaporized, the fuel sticks to the catalyst and causes catalyst poisoning. Therefore, the fuel supplied from the addition nozzle 37 needs to be atomized and supplied into the exhaust passage and supplied to the catalyst in a vaporized state.

  If the fuel supply amount in the cylinder 11 is reduced below the normal injection amount Go when the operation state (N, F) is in the low temperature region Le, the temperature of the exhaust gas discharged from the cylinder 11 becomes lower. Therefore, the fuel injected from the addition nozzle 37 to add the fuel to the post-processing device 30 is difficult to atomize. Stopping the control to reduce the fuel supply amount in the cylinder 11 below the normal injection amount Go when the operation state (N, F) is in the low temperature region Le is preferable in terms of atomization of the fuel injected from the addition nozzle 37. .

In the present invention, the following embodiments are also possible.
If the amount of decrease in the fuel injection amount in the cylinder 11 that is the specific cylinder and the sum of the increase in fuel injection amount in the other cylinders 12 to 14 are the same amount, the fuel injection amount in the other cylinders 12 to 14 The increment may not be the same for each cylinder 12-14.

  The addition nozzle 37 may be attached to the branch pipe portion of the exhaust manifold 28. The addition nozzle 37 attached to the branch pipe portion of the exhaust manifold 28 injects fuel into the branch pipe portion.

  The present invention may be applied to a diesel engine that does not use the exhaust manifold 28. As an exhaust passage structure of such an engine, there is a structure in which exhaust gas discharged from each cylinder joins immediately after the exhaust port or in the exhaust port. Even in such an engine, the present invention can be applied by disposing the addition nozzle 37 so as to face the exhaust port upstream of the exhaust gas merging portion.

O The fuel supply to the addition nozzle 37 may be configured to supply the fuel from the fuel pump 20 without using the addition pump 38.
O You may apply this invention to the diesel engine using the post-processing apparatus for particulate matter (PM) which is an unclean substance, and the post-processing apparatus for sulfur (S) which is an unclean substance.

  As the post-processing device 30, DPNR (diesel / particulate / NOx / reduction) may be used. DPNR is configured by coating NOx occlusion reduction type catalyst on the filter base material corresponding to DPF (diesel particulate filter), and purifies both PM (particulate matter) and NOx. Have

The present invention may be applied to a gasoline engine that injects fuel from a fuel injection nozzle into an intake port.
The technical idea that can be grasped from the embodiment described above will be described below.

  [1] In the increase / decrease control, the amount of decrease in the fuel injection amount of the specific cylinder and the sum of the increase of the fuel injection amount in the other cylinders are the same amount. The fuel-injection control apparatus in the internal combustion engine of description.

  The output performance does not change compared to when output control is not performed.

The 1st embodiment is shown and (a) is the whole diesel engine lineblock diagram. (B1) is a graph showing the fuel injection amount in each cylinder in the increase / decrease control. (B2) is a graph showing a change in the amount of clogging in the addition nozzle 37; (C1) is a graph showing the fuel injection amount in each conventional cylinder. (C2) is a graph which shows the change of the clogging amount in the conventional addition nozzle. The flowchart which shows a fuel-injection control program. The rotation-load graph which shows 2nd Embodiment. The flowchart which shows a fuel-injection control program. The flowchart which shows the fuel-injection control program of 3rd Embodiment. The rotation-load graph which shows 4th Embodiment. The graph which shows the fuel injection quantity in each cylinder in increase / decrease control. The flowchart which shows a fuel-injection control program. The flowchart which shows the fuel-injection control program of 5th Embodiment.

Explanation of symbols

  10 ... Diesel engine. 11 ... A specific cylinder. 12, 13, 14 ... cylinders. 16, 17, 18, 19 ... Fuel injection nozzles constituting fuel supply means. 20 ... A fuel pump constituting the fuel supply means. 28 ... Exhaust manifold. 281 ... Junction. 32A: Exhaust port that constitutes an addition target branch. 34A: A branch pipe part that constitutes an addition target tributary part. 30: Post-processing device. 35 ... A crank angle detector constituting the operating state detecting means. 36. An accelerator sensor that constitutes an operating state detecting means. 37 ... Addition nozzle constituting fuel addition means. 38 ... An addition pump constituting fuel addition means. C: A control computer constituting clogging prevention control means, operation state detection means, and fuel supply control means. Go: A fuel injection amount that is a normal supply amount. L: Low temperature region. H: High temperature region.

Claims (6)

A plurality of cylinders for accommodating pistons; a fuel supply means for supplying fuel to the plurality of cylinders; a fuel supply control means for controlling fuel supply to the plurality of cylinders by the fuel supply means; The exhaust gas is discharged into the exhaust gas in the exhaust passage that joins the exhaust gas discharged from the exhaust passage and introduces it into the post-treatment device that purifies the unclean substances after the joining, and the branch target to be added upstream from the joining portion of the exhaust passage. Fuel addition means having an addition nozzle to be added, clog prevention control means for controlling clog prevention injection for injecting the fuel from the addition nozzle to prevent clogging in the addition nozzle, and an operation state for detecting an operation state In a fuel injection control device in an internal combustion engine comprising a detection means,
The fuel supply control means determines the fuel supply amount per cylinder in at least a part of the entire operating state area detected by the operating state detection means in a specific cylinder that discharges exhaust gas to the addition target branch section. A fuel injection control device in an internal combustion engine that performs increase / decrease control to increase the fuel supply amount in the other cylinders from the normal supply amount while reducing the fuel supply amount from the normal supply amount.   2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel supply control means performs the increase / decrease control when the operation state detected by the operation state detection means is in a high temperature region.   The fuel supply control unit gradually decreases the fuel supply amount in the specific cylinder from the normal supply amount as the operation state detected by the operation state detection unit shifts from the low temperature region to the high temperature region. At the same time, the first gradual change control for gradually increasing the fuel supply amount in the other cylinders from the normal supply amount is performed, and the fuel supply control means detects that the operation state detected by the operation state detection means is low from a high temperature region. As the region shifts, the fuel supply amount in the specific cylinder is gradually increased to return to the normal supply amount, and the fuel supply amount in the other cylinders is gradually decreased to the normal supply amount. The fuel injection control device for an internal combustion engine according to claim 2, wherein the second gradual change control is performed.   2. The fuel injection control apparatus for an internal combustion engine according to claim 1, wherein the fuel supply control means performs the increase / decrease control in the entire region of the operation state detected by the operation state detection means.   When the operation state detected by the operation state detection unit is in a low temperature region and the fuel supply control unit adds the fuel to the post-processing device, the fuel supply amount in the specific cylinder is greater than the normal supply amount. The fuel injection control device for an internal combustion engine according to claim 4, wherein the control to reduce is stopped.   The fuel supply control means maintains a fuel supply amount in the specific cylinder at the normal supply amount and a fuel supply amount in other cylinders in a part of the operation state other than the operation state in which the increase / decrease control is performed. The fuel injection control apparatus for an internal combustion engine according to any one of claims 1 to 5, wherein control is performed to increase the normal supply amount.

Images