Control system for internal combustion engine

Abstract

To improve deposit removal efficiency in an EGR passage in a control system for an internal combustion engine.SOLUTION: A control system for an internal combustion engine 1 includes an exhaust manifold 8 and a control device 16. The exhaust manifold 8 is mounted to the internal combustion engine 1 having an exhaust gas recirculation system 10, and includes a plurality of exhaust gas inlet parts 24 connected to a plurality of cylinders 2 and an EGR inlet part 26 connected to an EGR passage 11 on one end side in the lining direction of the exhaust gas inlet parts 24. In deposit removal control in the EGR passage 11, the control device 16 causes fuel to be injected while an exhaust valve 4 is opened in a nearest cylinder #4 that is the cylinder 2 connected to the exhaust gas inlet part 24 located nearest to the EGR inlet part 26 out of the plurality of exhaust gas inlet parts 24.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This invention relates to a control system for removing deposits (products of incomplete combustion) that adhere to the EGR passage of an internal combustion engine. [Background technology]

[0002] One type of control that is performed in an internal combustion engine having an exhaust gas recirculation (EGR) system is to remove deposits in the EGR passage. For example, a control that blows off deposits by opening a closed EGR valve and strengthening the flow of exhaust gas in the EGR passage is known. Another type of control that blows off deposits is known, in which a fresh air introduction passage is connected to the EGR passage and fresh air is introduced into the EGR passage as necessary (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-132160 A [Patent Document 2] JP 2014-129725 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned control, deposits are blown away and removed by gas such as exhaust gas and fresh air. However, it takes time to remove deposits attached to the inner wall of the EGR passage using only the flow of gas, making it difficult to improve the efficiency of deposit removal. In addition, as the flow rate of gas increases, the inner wall of the EGR passage and the deposits tend to cool, which may actually make the deposits more likely to stick.

[0005] One of the objectives of the present invention, which has been devised in light of the above-mentioned problems, is to provide an internal combustion engine control system that can improve the efficiency of deposit removal from the EGR passage. However, in addition to this objective, another objective of the present invention is to achieve effects that are derived from the configurations shown in the "Description of Embodiments" described below and that cannot be obtained with conventional techniques. [Means for solving the problem]

[0006] The disclosed internal combustion engine control system can be realized as the following disclosed aspects (application examples), which solve at least part of the above problems. Each of the aspects from aspect 2 onwards is an aspect that can be selected additionally as appropriate, and each of the aspects can be omitted. None of the aspects from aspect 2 onwards discloses an essential aspect or configuration for the present case.

[0007] Aspect 1. The disclosed control system for an internal combustion engine includes an exhaust manifold and a control device. The exhaust manifold is attached to an internal combustion engine having an exhaust gas recirculation system, and has a plurality of exhaust inlets connected to a plurality of cylinders and an EGR inlet connected to an EGR passage at one end side in the arrangement direction of the exhaust inlets. In addition, the control device, during deposit removal control of the EGR passage, injects fuel into a proximate cylinder, which is the cylinder connected to the exhaust inlet closest to the EGR inlet among the plurality of exhaust inlets, while the exhaust valve is open.

[0008] Aspect 2. In any of the aspects including Aspect 1 described above, it is preferable that the control device fully opens an EGR valve disposed in the EGR passage during the deposit removal control. Aspect 3. In an aspect including the aspect 1 described above, it is preferable that, during the deposit removal control, the control device sets the lower limit of the fuel injection amount in the nearest cylinder to a value obtained by multiplying the minimum fuel amount that is the flammability limit in a single cylinder by the number of cylinders.

[0009] Aspect 4. In any of the aspects including Aspect 1 above, it is preferable that the control device executes the deposit removal control during fuel cut control or high load operation of the internal combustion engine. Aspect 5. In the aspect including Aspect 1 above, it is preferable that the control system includes an exhaust purification device disposed downstream of the exhaust manifold. It is preferable that the control device performs the deposit removal control when a catalyst temperature of the exhaust purification device is equal to or lower than a predetermined temperature.

[0010] Aspect 6. In an aspect including the aspect 1 above, it is preferable that the exhaust manifold is connected to a downstream exhaust system device and has an exhaust outlet portion that is located on the other end side rather than the center portion in the arrangement direction of the exhaust inlet portions. Effect of the Invention

[0011] According to the disclosed control system for an internal combustion engine, by injecting the deposit removal fuel while the exhaust valve is open in the nearest cylinder connected to the exhaust inlet closest to the EGR inlet, the deposit removal fuel can be efficiently caused to flow into the EGR passage. Therefore, the deposits adhering to the inside of the EGR passage can be washed away in a short time, and the efficiency of removing the deposits in the EGR passage can be improved. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a schematic diagram for explaining a control system for an internal combustion engine. [Diagram 2] FIG. 2 is a cross-sectional view of an exhaust manifold. [Diagram 3] 4 is a graph showing an open period of an exhaust valve. [Figure 4] 4 is a flowchart of a deposit removal control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [1. Equipment configuration] A control system as an embodiment of the present invention is applied to an internal combustion engine 1 shown in FIG. 1. This internal combustion engine 1 is a multi-cylinder engine having an EGR system 10 (exhaust gas recirculation system), such as a gasoline engine or a diesel engine. FIG. 1 illustrates a four-cylinder engine. #1 to #4 in the figure are cylinder numbers given for the sake of convenience. The multiple cylinders 2 are arranged, for example, in a line when viewed from above the internal combustion engine 1. The number of cylinder banks (banks) may be one or more. Furthermore, the arrangement of the multiple cylinders 2 does not have to be strictly linear, and may be a staggered arrangement.

[0014] Each cylinder 2 is provided with an intake valve 3 and an exhaust valve 4. The intake valve 3 closes the internal space of the cylinder 2 so as to be openable to an intake port (an intake passage provided in the cylinder head). Similarly, the exhaust valve 4 closes the internal space of the cylinder 2 so as to be openable to an exhaust port (an exhaust passage provided in the cylinder head). The dashed lines in Fig. 1 represent the intake port and the exhaust port. The number of each of the intake valve 3 and the exhaust valve 4 provided in one cylinder 2 may be one or more.

[0015] An intake manifold 6 is attached upstream of the intake port when the flow direction of the intake air is used as a reference. Further upstream of the intake manifold 6, there are provided intake passage 7 and intake system devices such as a throttle valve, an air cleaner, and a turbocharger compressor (not shown). Furthermore, an exhaust manifold 8 is attached downstream of the exhaust port. Further downstream of the exhaust manifold 8, there are provided an exhaust passage 9, an exhaust purification device 14, and a turbocharger turbine (not shown). The outlined arrows in FIG. 1 indicate the flow direction of the intake air and exhaust gas.

[0016] The internal combustion engine 1 is provided with an injector 5 for supplying fuel to each cylinder 2. The injector 5 is provided so as to supply fuel to the inside of the cylinder 2 or upstream of the intake valve 3. The injector 5 that injects fuel into the inside of the cylinder 2 is called an in-cylinder injection valve, and the injector 5 that injects fuel upstream of the intake valve 3 is called an in-intake pipe injection valve. The in-cylinder injection valve includes a direct injection type in-cylinder injection valve that directly injects fuel into the internal space of the cylinder 2 and an auxiliary chamber type in-cylinder injection valve that injects fuel into an auxiliary chamber of the cylinder 2 (not shown). The in-intake pipe injection valve includes a port injection valve that injects fuel into an intake port and an intake manifold injection valve that injects fuel into the inside of the intake manifold 6. The operating state of the injector 5 is controlled by a control device 16, which will be described later.

[0017] The internal combustion engine 1 has an EGR system 10 that recirculates a portion of the exhaust gas to the intake system. The main effects of the EGR system 10 include improved exhaust gas performance (reduced NOx), reduced combustion peak temperature (reduced knocking and noise), and improved fuel economy (reduced pumping loss). The EGR system 10 shown in FIG. 1 has an EGR passage 11, an EGR valve 12, and an EGR cooler 13.

[0018] The EGR passage 11 is a passage for introducing exhaust gas in the exhaust manifold 8 to the intake manifold 6. The exhaust gas passing through the EGR passage 11 is also called EGR gas. The upstream end of the EGR passage 11, based on the flow direction of the EGR gas, is connected to the exhaust manifold 8. The downstream end of the EGR passage 11 is connected to the intake manifold 6 and the intake passage 7. Deposits (products that are generated and accumulated mainly due to incomplete combustion of fuel and engine oil) contained in the EGR gas adhere to the inner wall surface of the EGR passage 11. Deposit removal control for removing these deposits is performed by the control device 16.

[0019] The EGR valve 12 is a valve that is provided in the EGR passage 11 to adjust the flow rate of EGR gas. The EGR cooler 13 is a heat exchanger that is provided in the EGR passage 11 to cool the EGR gas. The operating states of the EGR valve 12 and the EGR cooler 13 are controlled by a control device 16. The positions of the EGR valve 12 and the EGR cooler 13 can be set to any positions in the EGR passage 11. The EGR cooler 13 may be omitted from the EGR system 10.

[0020] The exhaust purification device 14 is a device that incorporates a catalyst and a filter for purifying air pollutants contained in the exhaust gas. The exhaust purification device 14 includes an oxidation catalyst device, a trap catalyst device, a particulate removal filter device, and the like. Specific examples of air pollutants that are purified by the exhaust purification device 14 include unburned fuel components (HC), nitrogen oxides (NOx), sulfur oxides (SOx), carbon monoxide (CO), particulate matter (PM), and deposits. A catalyst temperature sensor 15 for detecting the catalyst temperature is provided inside or near the exhaust purification device 14. Information on the catalyst temperature detected here is transmitted to the control device 16.

[0021] Fig. 2 is a cross-sectional view for explaining the internal structure of the exhaust manifold 8. The white arrows in Fig. 2 indicate the flow direction of exhaust gas inside the exhaust manifold 8. The exhaust manifold 8 has a main body 21 forming a collecting pipe that bundles together multiple flows of exhaust gas discharged from each cylinder 2, a flat upstream flange 22 provided on an end face of the main body 21 on the internal combustion engine 1 side (upstream side), and a flat downstream flange 23 provided on an end face of the main body 21 on the exhaust passage 9 side (downstream side).

[0022] The upstream flange portion 22 is fixed in surface contact with an end face of the cylinder head of the internal combustion engine 1, which is the outlet of the exhaust port. The upstream flange portion 22 is provided with a plurality of exhaust inlet portions 24 connected to the plurality of cylinders 2, and an EGR inlet portion 26 connected to the EGR passage 11. The exhaust inlet portions 24 are holes that are connected to the exhaust ports of the internal combustion engine 1. The EGR inlet portion 26 is a hole that is connected to the EGR passage 11, and is formed at one end side in the arrangement direction of the exhaust inlet portions 24.

[0023] The downstream flange portion 23 is fixed in face-to-face contact with an end face that serves as an exhaust gas inlet in the exhaust passage 9 or a turbocharger (not shown). An exhaust outlet portion 25 that serves as an exhaust gas outlet is provided in the downstream flange portion 23. The exhaust outlet portion 25 is connected in communication with the exhaust passage 9 on the downstream side. When exhaust system devices such as the exhaust purification device 14 and a turbocharger (not shown) are connected immediately downstream of the exhaust manifold 8, the exhaust outlet portion 25 is connected in communication with these exhaust system devices.

[0024] Here, one end side of the exhaust inlet portion 24 in the arrangement direction will be described in detail. In the paper of FIG. 2, the exhaust inlet portions 24 are arranged side by side, so this left-right direction is defined as the "arrangement direction". The EGR inlet portion 26 is arranged at one end side (either the left or right end side) in the arrangement direction. In other words, the EGR inlet portion 26 is arranged further toward the end side than the #4 cylinder located at the end of the arrangement direction. In addition, among the multiple exhaust inlet portions 24, the cylinder 2 connected to the exhaust inlet portion 24 closest to the EGR inlet portion 26 is called the "closest cylinder". The EGR inlet portion 26 is arranged at a position close to the exhaust inlet portion 24 of the closest cylinder (#4 cylinder) and at a position away from the exhaust inlet portions 24 of the cylinders 2 (#1 to #3 cylinders) other than the closest cylinder.

[0025] 2, center line C1 represents the center of exhaust inlet portion 24 connected to #1 cylinder. Similarly, center line C2 represents the center of exhaust inlet portion 24 connected to #2 cylinder, center line C3 represents the center of exhaust inlet portion 24 connected to #3 cylinder, and center line C4 represents the center of exhaust inlet portion 24 connected to #4 cylinder. Center line C5 represents the center of EGR inlet portion 26 connected to EGR passage 11, and center line C6 represents the center of exhaust outlet portion 25. Center line C0 is a line located midway between center line C2 and center line C3, and corresponds to the center of exhaust inlet portions 24 in the arrangement direction. Center lines C0 to C6 are all parallel to each other.

[0026] The distance from the center line C5 to the center line C4 is set shorter than the distance from the center line C5 to each of the center lines C1 to C3. The distance from the center line C0 to the center line C5 is set longer than the distance from the center line C0 to the center line C4. The exhaust outlet section 25 is preferably disposed on the other end side of the center (center line C0) in the arrangement direction of the exhaust inlet sections 24. In other words, the exhaust outlet section 25 is preferably disposed at a position as far away as possible from the EGR inlet section 26. The center line C6 is preferably disposed on the opposite side of the center line C0 to the center line C5.

[0027] [2. Control configuration] The control device 16 is a computer (electronic control unit, ECU) with a built-in processor (arithmetic processing device) and memory (storage device), and performs deposit removal control to remove deposits that have built up in the EGR passage 11. The deposit removal control is a control in which deposit removal fuel is injected while the exhaust valve 4 is open in the nearest cylinder. The deposit removal fuel injected here is introduced into the EGR passage 11 via the exhaust manifold 8 and acts to wash away deposits that have built up in the EGR passage 11.

[0028] During this deposit removal control, the EGR valve 12 disposed in the EGR passage 11 may be fully opened. This increases the flow rate of EGR gas and improves the efficiency of deposit removal. In addition, the flow of fuel through the EGR passage 11 is stabilized, improving the effect of washing away deposits. However, since there is a risk of unintended torque fluctuations occurring if the EGR valve 12 is fully opened during normal operation of the internal combustion engine 1, the EGR valve 12 may be fully opened on the precondition that the internal combustion engine 1 is under fuel cut control.

[0029] The contents of the deposit removal control (control program) are stored in memory, and the contents are loaded into the processor as appropriate and executed. Well-known conditions can be applied as the conditions for implementing the deposit removal control (start conditions, end conditions). Specific examples of start conditions for the deposit removal control are shown below. The control device 16 starts the deposit removal control when any of the following conditions is met while the deposit removal control is not being implemented. The estimated deposit amount in the EGR passage 11 is greater than or equal to the specified amount. The cumulative amount of EGR gas flowing through the EGR passage 11 is equal to or greater than the standard amount. The EGR valve 12 is open for a period longer than the reference period.

[0030] Specific examples of conditions for terminating the deposit removal control are shown below. When, for example, the deposit removal control is in an implementation state, the controller 16 terminates the deposit removal control if any of the following conditions is met. The estimated deposit amount in the EGR passage 11 is equal to or less than a second predetermined amount. The cumulative amount of EGR gas or fuel passing through the deposit removal control is equal to or greater than the second standard amount. The implementation time of deposit removal control is equal to or longer than the second reference time.

[0031] Examples of additional conditions related to deposit removal control are given below. For example, when deposit removal control is not being implemented, the control device 16 may not start deposit removal control unless any (or all) of the following conditions are met. Also, for example, when deposit removal control is being implemented, if any (or all) of the following conditions are no longer met, the control device 16 may immediately end the deposit removal control. - Internal combustion engine 1 is under fuel cut control. - Internal combustion engine 1 is operating at high load. The catalyst temperature of the exhaust purification device 14 is below a predetermined temperature.

[0032] Fuel cut control is a control that temporarily stops (cuts) fuel injection for operating the internal combustion engine 1 when coasting with the accelerator off or when decelerating. High-load operation is an operating state in which the required torque or output torque of the internal combustion engine 1 is equal to or greater than a relatively high predetermined torque. In the case where the internal combustion engine 1 drives a generator (not shown) to generate electricity, the high-load operation includes an operating state in which the amount of electricity generated is relatively large.

[0033] During deposit removal control, the deposit removal fuel flows into the intake manifold 6 through the EGR passage 11 and into each cylinder 2, so that the amount of fuel supplied to the cylinder 2 is greater than that immediately before the deposit removal control was started, causing torque fluctuations. If deposit removal control is performed during fuel cut control or high-load operation, torque fluctuations caused by the combustion of the deposit removal fuel become less noticeable, improving the driving feel. When deposit removal control is performed during fuel cut control in a gasoline engine, it is preferable to also perform ignition control. This allows the deposit removal fuel to be burned in each cylinder 2 when it flows into each cylinder 2, making it possible to suppress unburned fuel from being discharged to the outside through the exhaust passage 9.

[0034] A portion of the deposit removal fuel injected by deposit removal control flows into the exhaust passage 9 without being introduced into the EGR passage 11, and is purified by the exhaust purification device 14. Therefore, if deposit removal control is performed when the catalyst temperature of the exhaust purification device 14 exceeds a predetermined temperature, there is a risk that the temperature of the exhaust purification device 14 (catalyst) will increase excessively. On the other hand, if deposit removal control is performed when the catalyst temperature is below the predetermined temperature, such concerns can be eliminated.

[0035] The deposit removal fuel is supplied only to the nearest cylinder out of the multiple cylinders 2. In this embodiment, the deposit removal fuel is supplied only to cylinder #4, and not to cylinders #1 to #3. By injecting the deposit removal fuel into the nearest cylinder while the exhaust valve 4 is open, much of the deposit removal fuel is introduced into the EGR passage 11 through the EGR inlet portion 26, efficiently removing deposits. Furthermore, because the deposit removal fuel is not supplied to cylinders other than the nearest cylinder, excessive fuel consumption is suppressed, and unburned fuel is suppressed from being discharged to the outside through the exhaust passage 9.

[0036] When deposit removal control is performed during fuel cut control of the internal combustion engine 1, deposit removal fuel is injected into the nearest cylinder with normal fuel injection (fuel injection during the intake stroke, compression stroke, and combustion stroke) stopped. Also, when deposit removal control is performed during normal operation or high load operation of the internal combustion engine 1, deposit removal fuel is injected into the nearest cylinder separately from the normal fuel injection.

[0037] The fuel injection amount of the deposit removal fuel is preferably set to a lower limit value of the minimum fuel amount, which is the flammability limit in a single cylinder 2, multiplied by the number of cylinders. As a result, even if the deposit removal control is performed during the fuel cut control of the internal combustion engine 1, the EGR gas containing the unburned fuel corresponding to the minimum fuel amount is supplied to each cylinder 2, so that the unburned fuel can be burned in the cylinder 2. At this time, if the amount of unburned fuel is the minimum fuel amount, the torque fluctuation due to combustion is suppressed to a minimum. Also, in consideration of the combustion stability, it is conceivable to inject the deposit removal fuel slightly more than the "value obtained by multiplying the minimum fuel amount by the number of cylinders". In this sense, it is preferable that the fuel injection amount of the deposit removal fuel is set to the "value obtained by multiplying the minimum fuel amount by the number of cylinders" as the lower limit value.

[0038] FIG. 3 is a graph showing the open period of the exhaust valve 4 of the nearest cylinder (cylinder #4). The deposit removal fuel is injected into the nearest cylinder while the exhaust valve 4 of the nearest cylinder is open. When the injector 5 is an in-cylinder injection valve, if fuel is injected while the exhaust valve 4 is open, the exhaust gas containing the fuel is immediately discharged into the exhaust manifold 8 and introduced into the EGR passage 11. When the injector 5 is an in-intake pipe injection valve, the fuel injected while the exhaust valve 4 is open is discharged into the exhaust manifold 8 via the cylinder 2 during the valve overlap period when the open period of the intake valve 3 and the open period of the exhaust valve 4 overlap, and introduced into the EGR passage 11.

[0039] [3. Flowchart] 4 is a flowchart illustrating the procedure for deposit removal control. The control contents of this flowchart are repeatedly executed at a predetermined cycle. Steps A1 to A3 are steps related to determining the start conditions of deposit removal control, steps A4 to A6 are steps related to the contents of deposit removal control, and step A7 is a step related to determining the end conditions of deposit removal control.

[0040] In step A1, it is determined whether the estimated deposit amount in the EGR passage 11 is equal to or greater than a predetermined amount. If this condition is not met, the flow ends, and if it is met, the process proceeds to step A2. In step A2, it is determined whether the internal combustion engine 1 is under fuel cut control or in high load operation. If this condition is not met, the flow ends, and if it is met, the process proceeds to step A3. In step A3, it is determined whether the catalyst temperature of the exhaust purification device 14 is equal to or less than a predetermined temperature. If this condition is not met, the flow ends, and if it is met, the process proceeds to step A4.

[0041] In step A4, the control device 16 calculates the fuel injection amount of the deposit removal fuel. The fuel injection amount calculated here is, for example, a value obtained by multiplying the minimum fuel amount for one cylinder 2 by 4, which is the number of cylinders. This improves the combustion stability in each cylinder 2 when the deposit removal fuel is introduced into each cylinder 2 via the EGR passage 11. In addition, in step A5, the control device 16 fully opens the EGR valve 12 interposed in the EGR passage 11. This increases the flow rate of EGR gas, improving the efficiency of deposit removal. Note that step A5 may be performed only when the internal combustion engine 1 is under fuel cut control. This makes torque fluctuations caused by an increase in the flow rate of EGR gas less noticeable, improving the driving feeling.

[0042] In the next step A6, deposit removal fuel is injected into the nearest cylinder, #4, while the exhaust valve 4 is open. The deposit removal fuel is discharged into the exhaust manifold 8 without being burned inside the cylinder 2. Most of the deposit removal fuel passes through the EGR inlet portion 26 and is introduced into the EGR passage 11, where it acts to wash away deposits that have built up in the EGR passage 11. The fuel that has washed away the deposits passes through the intake manifold 6 and flows into each cylinder 2 together with the washed-out deposits.

[0043] In step A7, it is determined whether or not the termination condition for deposit removal control is satisfied. For example, if the estimated deposit amount in the EGR passage 11 becomes equal to or less than a second predetermined amount that is smaller than a predetermined amount, if the fuel cut control is terminated, if the engine is no longer operating at high load, or if the catalyst temperature exceeds a predetermined temperature, it is determined that the termination condition is satisfied and this flow ends. If the termination condition is not satisfied, the flow proceeds to step A6, and the deposit removal control continues until the termination condition is satisfied.

[0044] [4. Actions and Effects] (1) The control system for the internal combustion engine 1 according to this embodiment includes an exhaust manifold 8 and a control device 16. The exhaust manifold 8 is attached to the internal combustion engine 1 having an EGR system 10, and has a plurality of exhaust inlet portions 24 connected to a plurality of cylinders 2, and an EGR inlet portion 26 connected to the EGR passage 11 at one end side in the arrangement direction of the exhaust inlet portions 24. Furthermore, during deposit removal control of the EGR passage 11, the control device 16 injects fuel while the exhaust valve 4 is open in the nearest cylinder, which is the cylinder 2 connected to the exhaust inlet portion 24 that is closest to the EGR inlet portion 26 among the plurality of exhaust inlet portions 24.

[0045] In this way, by injecting the deposit removal fuel while the exhaust valve 4 is open in the nearest cylinder connected to the exhaust inlet portion 24 closest to the EGR inlet portion 26, the deposit removal fuel can be efficiently introduced into the EGR passage 11. In other words, most of the deposit removal fuel can be made to flow into the EGR passage 11, and the amount of fuel leaking from the exhaust outlet portion 25 into the exhaust passage 9 can be reduced. Therefore, deposits adhering to the inside of the EGR passage 11 can be efficiently washed away in a short time, and the efficiency of deposit removal in the EGR passage 11 can be improved.

[0046] Furthermore, the deposit removal fuel can be supplied from the injector 5 that supplies fuel to the nearest cylinder, and there is no need to add a new deposit removal injection valve, for example, inside the EGR passage 11 or the exhaust manifold 8. This simplifies the configuration of the control system, leading to cost reductions. The injector 5 that injects the deposit removal fuel may be an in-cylinder injection valve or an in-intake pipe injection valve. The above control system is applicable to internal combustion engines 1 with any fuel supply method, and is highly technically versatile.

[0047] (2) The control device 16 can fully open the EGR valve 12 disposed in the EGR passage 11 during deposit removal control. This control can maximize the flow rate of EGR gas passing through the inside of the EGR passage 11, further improving the efficiency of deposit removal. In addition, the momentum of the EGR gas sucked into the EGR passage 11 from the EGR inlet 26 of the exhaust manifold 8 is increased, so that almost the entire amount of fuel for deposit removal introduced from the nearest cylinder can be supplied to the EGR passage 11. In other words, the amount of fuel leaking from the exhaust outlet 25 into the exhaust passage 9 can be significantly reduced, further improving the efficiency of deposit removal.

[0048] (3) When performing deposit removal control, the control device 16 can execute control such that the minimum fuel amount that is the flammability limit in a single cylinder 2 multiplied by the number of cylinders is set as the lower limit of the fuel injection amount in the nearest cylinder. With this control, even if deposit removal control is executed during fuel cut control of the internal combustion engine 1, EGR gas containing unburned fuel corresponding to the minimum fuel amount can be supplied to each cylinder 2, and the unburned fuel can be burned. Therefore, leakage of unburned fuel into the exhaust passage 9 can be prevented, and exhaust purification performance can be improved. In addition, since the amount of unburned fuel corresponds to the minimum fuel amount, torque fluctuations due to combustion can be suppressed to a minimum.

[0049] (4) The control device 16 described above can perform deposit removal control during fuel cut control or high load operation of the internal combustion engine 1. In other words, the control device 16 can adopt, as a start condition for deposit removal control, that the internal combustion engine 1 is under fuel cut control or is under high load operation. By using these start conditions, torque fluctuations caused by the combustion of the deposit removal fuel can be made less noticeable, preventing deterioration of NVH (Noise Vibration Harshness) and improving the driving feeling.

[0050] (5) The above control system includes an exhaust purification device 14 disposed downstream of the exhaust manifold 8. The above control device 16 can also perform deposit removal control when the catalyst temperature of the exhaust purification device 14 is equal to or lower than a predetermined temperature. In other words, the control device 16 can employ, as a start condition for deposit removal control, that the catalyst temperature of the exhaust purification device 14 is equal to or lower than a predetermined temperature. By using this start condition, it is possible to prevent the exhaust purification device 14 from overheating, and to prevent deterioration of the exhaust purification device 14 and a decrease in exhaust purification performance.

[0051] (6) As shown in FIG. 2, the exhaust manifold 8 has an exhaust outlet 25 connected to a downstream exhaust system (exhaust passage 9). The exhaust outlet 25 is disposed on the other end side of the center of the exhaust inlet 24 in the arrangement direction. In other words, the center line C6 of the exhaust outlet 25 is disposed on the opposite side of the center line C0 to the center line C5 of the EGR inlet 26. By separating the exhaust outlet 25 from the EGR inlet 26 in this way, most of the deposit removal fuel flowing from the nearest cylinder can be made to flow into the EGR passage 11, and the amount of fuel leaking from the exhaust outlet 25 to the exhaust passage 9 can be reduced. Therefore, the efficiency of deposit removal in the EGR passage 11 can be further improved.

[0052] [5.Other] The above embodiment is merely illustrative and is not intended to exclude various modifications or application of techniques not specified in the embodiment. Each configuration of the embodiment can be modified in various ways without departing from the spirit of the embodiment. Furthermore, each configuration of the embodiment can be selected or combined as necessary.

[0053] The internal combustion engine 1 to which the control system of this embodiment is applied may be a multi-cylinder engine having at least an exhaust gas recirculation system, and may be a gasoline engine or a diesel engine, regardless of the number of cylinders or the arrangement of cylinders. The vehicle on which the internal combustion engine 1 is mounted may be an internal combustion vehicle or a hybrid vehicle. At least, in deposit removal control of the EGR passage 11, by injecting fuel while the exhaust valve 4 is open in the nearest cylinder, which is the cylinder 2 connected to the exhaust inlet 24 closest to the EGR inlet 26, the efficiency of deposit removal in the EGR passage 11 can be improved without adding a new deposit removal injection valve. [Industrial Applicability]

[0054] This invention can be used in the manufacturing industry of control systems applied to internal combustion engines having exhaust gas recirculation systems, and can also be used in the manufacturing industry of automobiles, ships, driving force generating devices, power generating devices, etc., which are equipped with internal combustion engines having exhaust gas recirculation systems and control systems. [Explanation of symbols]

[0055] 1. Internal combustion engine 2-cylinder 3 Intake valve 4 Exhaust valve 5. Injectors 6 Intake manifold 7 Intake passage 8 Exhaust manifold 9 Exhaust passage 10 EGR system (exhaust gas recirculation system) 11 EGR passage 12 EGR valve 13 EGR cooler 14 Exhaust purification device 15 Catalyst temperature sensor 16 Control device 21 Main body 22 Upstream flange 23 Downstream flange 24 Exhaust inlet 25 Exhaust outlet 26 EGR inlet C0~C6 center line

Claims

1. an exhaust manifold attached to an internal combustion engine having an exhaust gas recirculation system, the exhaust manifold having a plurality of exhaust inlet portions connected to a plurality of cylinders and an EGR inlet portion connected to an EGR passage at one end side in an arrangement direction of the exhaust inlet portions; a control device that, during deposit removal control of the EGR passage, injects fuel while an exhaust valve is open in a proximate cylinder that is connected to the exhaust inlet portion that is closest to the EGR inlet portion among the plurality of exhaust inlets; A control system for an internal combustion engine comprising:

2. The control device fully opens an EGR valve disposed in the EGR passage during the deposit removal control.

2. The control system for an internal combustion engine according to claim 1 .

3. The control device, during the deposit removal control, sets a value obtained by multiplying a minimum fuel amount that is a flammability limit in a single cylinder by the number of cylinders as a lower limit value of the fuel injection amount in the nearest cylinder.

2. The control system for an internal combustion engine according to claim 1 .

4. The control device performs the deposit removal control during fuel cut control or high load operation of the internal combustion engine.

2. The control system for an internal combustion engine according to claim 1 .

5. an exhaust purification device disposed downstream of the exhaust manifold, The control device performs the deposit removal control when a catalyst temperature of the exhaust purification device is equal to or lower than a predetermined temperature.

2. The control system for an internal combustion engine according to claim 1 .

6. The exhaust manifold is connected to a downstream exhaust system device and has an exhaust outlet portion disposed on the other end side of the center portion in the arrangement direction of the exhaust inlet portions.

2. The control system for an internal combustion engine according to claim 1 .

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