Internal combustion engine and methods for controlling it

Abstract

Internal combustion engine, featuring: an exhaust gas recirculation (EGR) injector (1) connected to a combustion chamber of the internal combustion engine (3) to inject EGR gas into the combustion chamber of the internal combustion engine (3); an EGR pipe (5) that connects the EGR injector (1) to an exhaust system of the internal combustion engine (3) and expels exhaust gas from the exhaust system; an EGR pump (7) which is mounted in the EGR pipe (5) and pumps the exhaust gas in the EGR pipe (5) to direct the exhaust gas to the EGR injector (1); and a control device (9) which is connected to the EGR pump (7) and the EGR injector (1) and is configured to control the EGR pump (7) and the EGR injector (1) so that the EGR injector (1) injects the EGR gas into the combustion chamber, wherein the EGR injector (1) is mounted in the combustion chamber such that a plurality of EGR gas sprays, which are injected in the direction of an inner circumference of the combustion chamber, reach the inner circumference of the combustion chamber simultaneously.

Description

[0001] The invention relates to an exhaust gas recirculation device for an internal combustion engine.

[0002] In general, an exhaust gas recirculation (EGR) device was used to suppress the generation of NOx in an internal combustion engine by recirculating exhaust gas, which is discharged from an internal combustion engine into a combustion chamber after combustion in the engine, thereby reducing the combustion chamber temperature.

[0003] A conventional EGR device is configured to feed exhaust gas, expelled from the downstream side of an exhaust manifold or aftertreatment system of an internal combustion engine, into an air intake manifold via an EGR line. The EGR device controls the opening ratio of the EGR line by means of an EGR valve, thus controlling the amount of EGR gas flowing into the combustion chamber.

[0004] With the EGR device, since the EGR quantity is sufficiently influenced by the air intake / exhaust pressures of the combustion engine, there is a problem that a desired EGR quantity cannot be ensured as a result of an increase in pressure on the side of the air intake manifold in a range of high combustion engine load or a range of high combustion engine speed.

[0005] Furthermore, even if the EGR valve is controlled based on the instantaneous state of the combustion chamber to ensure the desired EGR quantity, the EGR gas controlled by the EGR valve reaches the combustion chamber after a time delay. Therefore, there is a limit to the amount of EGR quantity that can be controlled for a given instantaneous combustion state of the internal combustion engine.

[0006] Meanwhile, an internal combustion engine with compression ignition, such as a diesel engine, requires an ignition delay period of a reasonable duration to increase the mixture ratio of fuel and air injected into the combustion chamber and to create a condition for trouble-free combustion of fuel.

[0007] Methods for ensuring the ignition retardation period include reducing the compression ratio, increasing the EGR quantity, delaying the fuel injection timing, and similar techniques. However, delaying the fuel injection timing does not increase the fuel-air mixture ratio, and increasing the EGR quantity and reducing the compression ratio lead to side effects such as excessive HC and CO in the exhaust gas, reduced combustion stability, and increased soot.

[0008] Furthermore, KR 10 1998 0 068 729 A and DE 10 2010 053 356 A1 disclose nozzles mounted in a cylinder head, which allow exhaust gas to be introduced into the vicinity of the EGR fuel injector before the start of fuel injection, as well as pumps for supplying the EGR injectors. A control device is also described in these documents. DE 10 2010 053 356 A1 further discloses that the EGR injection should only take place after the intake valve has closed, since otherwise the EGR gases would displace air from the cylinder and the increased air consumption could not be achieved. JP H05 - 44 492 A further discloses a control system for ignition delay and ignition timing, wherein EGR is injected via a nozzle in the cylinder head and concentrated around the diesel injector.

[0009] The invention provides an internal combustion engine and a method for controlling the internal combustion engine, wherein an optimal amount of exhaust gas recirculation (EGR) required at any given moment in a combustion chamber of the internal combustion engine is supplied to the combustion chamber immediately and precisely, so that the generation of NOx in the internal combustion engine can be efficiently suppressed, and wherein furthermore an ignition delay period and combustion of fuel injected into the combustion chamber are appropriately controlled, so that the mixture ratio of fuel and air can be increased and a more ideal combustion can be achieved.

[0010] According to the invention, an internal combustion engine according to claim 1 is provided, comprising an EGR (exhaust gas recirculation) injector nozzle (or EGR injector) connected to a combustion chamber of the internal combustion engine to inject EGR gas into the combustion chamber of the internal combustion engine, an EGR pipe (or EGR line) connecting the EGR injector nozzle to an exhaust system of the internal combustion engine and expelling exhaust gas from the exhaust system, an EGR pump mounted in the EGR pipe and pumping the exhaust gas in the EGR pipe to supply the exhaust gas to the EGR injector nozzle, and a control device connected to the EGR pump and the EGR injector nozzle and configured to control the EGR pump and the EGR injector nozzle so that the EGR injector nozzle injects the EGR gas into the combustion chamber. The EGR injector is mounted in the combustion chamber, so that a majority of EGR gas sprays (or...EGR gas jets), which are injected in the direction of a side wall of the combustion chamber, reaching the side wall of the combustion chamber simultaneously.

[0011] The EGR injector can be mounted on the top of the combustion chamber.

[0012] The EGR injector can be mounted in a central section of the combustion chamber.

[0013] The control unit can be configured to inject the EGR gas via the EGR injector before fuel is injected into the internal combustion engine.

[0014] The control unit can be configured to inject the EGR gas via the EGR injector after an air intake valve of the internal combustion engine has closed.

[0015] Furthermore, according to the invention, a method according to claim 12 for controlling the internal combustion engine according to the invention is provided, wherein the method may comprise: receiving internal combustion engine operating information by the control unit, determining whether a current internal combustion engine operating range requires exhaust gas recirculation or not, using the input internal combustion engine operating information by the control unit, and if it is determined that the current operating range requires exhaust gas recirculation, operating the EGR injector after the air intake valve is closed and before fuel injection begins, and enabling the EGR injector to inject EGR gas into the combustion chamber, by means of the control unit, wherein, if a torque requested by the internal combustion engine is equal to or greater than a predetermined reference torque, reducing the injection quantity of the EGR gas.which is injected into the combustion chamber by the control unit.

[0016] The control unit can increase the ignition delay period of the fuel by increasing the amount of EGR gas injected.

[0017] If it is necessary to ignite the fuel early, the control unit can be configured to control the fuel ignition point (or fuel ignition time) in the combustion chamber by reducing the amount of EGR gas injected.

[0018] If it is necessary to ignite the fuel early, the control unit can reduce the injection quantity to zero.

[0019] The control unit can be configured to control the EGR gas injection in such a way that it is carried out several times.

[0020] The control unit can reduce the amount of EGR gas injected into the combustion chamber depending on an increase in the torque requested by the internal combustion engine.

[0021] According to an exemplary embodiment of the invention, since the optimal EGR quantity currently required in the combustion chamber of the internal combustion engine is supplied immediately and precisely, NOx generation in the internal combustion engine can be effectively suppressed. Furthermore, since the ignition delay and combustion of the fuel injected into the combustion chamber are appropriately controlled, the fuel-air mixture ratio can be increased, and more ideal combustion can be achieved.

[0022] Furthermore, according to an exemplary embodiment of the invention, since the fuel EGR gas injected into the combustion chamber effectively prevents the combustion energy from being transferred to the side wall of the combustion chamber, an increase in temperature on the side wall of the combustion chamber is effectively suppressed, and therefore fuel efficiency can be improved.

[0023] The invention is explained in more detail with reference to the drawing. The drawing shows: Fig. 1 a conceptual diagram of an internal combustion engine according to an exemplary embodiment of the invention; Fig. 2 a view showing an example in which a fuel injector and an exhaust gas recirculation (EGR) injector are mounted on the top of a combustion chamber of the internal combustion engine according to an exemplary embodiment of the invention; Fig. 3 a flowchart illustrating an exemplary embodiment of a method for controlling the internal combustion engine according to an exemplary embodiment of the invention; Fig. 4 a view representing a combustion chamber in the case of a conventional internal combustion engine with compression ignition, wherein the injected fuel is ignited in the combustion chamber, in which the EGR gas distribution in the combustion chamber is overall equal, since the EGR gas is injected into the air that is drawn into the combustion chamber; and Fig. 5 to 7 views depicting a combustion process in the combustion chamber, wherein the combustion is carried out by adjusting the ignition delay period according to an exemplary embodiment of the invention.

[0024] It is understood that the attached drawings are not necessarily to scale and represent a somewhat simplified depiction of various features that illustrate the basic principles of the invention. The specific design features of the present invention, which include, for example, specific dimensions, orientations, positions, and shapes as disclosed herein, are partly determined by the intended application and environment of use.

[0025] In the figures, the reference numerals refer to the same or equivalent parts of the present invention throughout the individual figures of the drawing.

[0026] Various embodiments of the present invention will now be discussed in detail, examples of which are illustrated in the accompanying drawings and described below. Although the invention is described in connection with exemplary embodiments, it is understood that the present description is not intended to limit the invention to these exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the invention as defined by the accompanying claims.

[0027] With regard to the Fig. 1 and Fig. 2 comprises an internal combustion engine according to an exemplary embodiment of the invention: an EGR injector nozzle 1, which is mounted in a combustion chamber, so that EGR gas sprays, which are injected in the direction of a side wall 2 of the combustion chamber, reach the side wall 2 of the combustion chamber simultaneously, an EGR pipe 5, which expels exhaust gas from an exhaust system of the internal combustion engine 3, an EGR pump 7, which pumps the exhaust gas in the EGR pipe 5 to direct the exhaust gas to the EGR injector nozzle 1, and a control device 9, which controls the EGR pump 7 and the EGR injector nozzle 1, so that the EGR injector nozzle 1 injects EGR gas into the combustion chamber.

[0028] This means that the internal combustion engine according to the invention injects EGR gas via the EGR injector nozzle 1, enabling the injected EGR gas splatters to be applied simultaneously to the side wall 2 in the circular combustion chamber. As such, the ignition delay and combustion of the injected fuel are controlled, thereby increasing the fuel-air mixture ratio and enabling more efficient combustion. In other words, since the internal combustion engine is configured to reduce harmful exhaust gases and improve thermal efficiency, the fuel efficiency of a vehicle in which the internal combustion engine is installed can be improved.

[0029] The EGR injector 1 is mounted on a central upper surface of the combustion chamber. For example, because the EGR injector 1 is mounted near a fuel injector 4, which is typically mounted on the central upper surface of the combustion chamber, as in Fig. Figure 2 shows that when the EGR injector 1 injects EGR gas, the EGR gas sprays simultaneously hit the side wall 2 of the circular combustion chamber, as shown in Figure 2. Fig. 5 is shown.

[0030] Naturally, the EGR injector 1 is preferably mounted near the fuel injector 4 within an area where the EGR injector 1 does not interfere with the fuel injector 4. Furthermore, the EGR injector 1 is preferably mounted such that it does not cover fuel splashes, as indicated by the arrows in the diagram. Fig. 2 is shown.

[0031] In contrast, the fuel injector 4 is preferably mounted at an angle which is separated from the paths of the EGR gas injected by the EGR injector 1.

[0032] As in Fig. As shown in Figure 1, the internal combustion engine 3 is equipped with an aftertreatment device 13 on the downstream side of a turbocharger 11. The internal combustion engine 3 is connected to the EGR pipe 5 via a switching valve 15 to switch between situations in which exhaust gas is discharged from the aftertreatment device 13 to an exhaust pipe and situations in which exhaust gas is fed to the EGR pipe 5. The internal combustion engine 3 is equipped with an exhaust gas recirculation (EGR) cooler 17 on the EGR pipe 5 to cool the EGR gas, which is exhaust gas.

[0033] The combustion engine 3 is configured such that EGR gas, which is cooled in the EGR cooler 17, is pumped by the EGR pump 7 and stored in an EGR rail 19, and then the EGR gas can be fed directly to the combustion chamber, since a plurality of EGR injectors 1 are opened separately as a result of the control of the control device 9.

[0034] Meanwhile, the internal combustion engine 3 is configured such that air, which is filtered in an air filter 21, is fed to a compressor of the turbocharger 11 and compressed, the compressed air is cooled in an intercooler 23, and the cooled air is directed to each combustion chamber of the internal combustion engine via an air intake manifold.

[0035] The control unit 9 can be incorporated into an internal combustion engine control unit 9 for controlling the fuel injector 4 and the like of the internal combustion engine 3 and can be configured separately to control the EGR injector 1, so that the control unit 9 can perform the control by mutual communication with the internal combustion engine control unit 9.

[0036] Furthermore, the discharge of exhaust gas from the combustion engine's exhaust system via the EGR pipe 5 encompasses both cases of exhaust gas discharged from the downstream side of the aftertreatment device 13 and exhaust gas discharged from its upstream side. The EGR pipe 5 can be configured to discharge exhaust gas from the upstream side of the aftertreatment device 13, and, of course, in the present case, given a blockage in the EGR injector 1, the EGR pipe 5 can be equipped with a separate filter.

[0037] An exemplary embodiment of a method for controlling the internal combustion engine according to the invention comprises: inputting internal combustion engine operating information to the control unit 9 (S10), determining, using the inputted internal combustion engine operating information, whether the current internal combustion engine operating range requires EGR or not, by the control unit 9 (S20), and if it is determined that the operating range requires EGR, operating the EGR injector 1 after an air intake valve is closed and before fuel injection begins, and enabling the EGR injector 1 to inject EGR gas into the combustion chamber, by the control unit 9 (S30), as shown in Fig. 3 is shown.

[0038] This means that when the control unit 9 has received the internal combustion engine operating information, such as an internal combustion engine speed, a crankshaft angle, a fuel injection timing, an effective brake medium pressure (BMEP), a coolant temperature, a combustion chamber pressure, etc., and determines that the internal combustion engine operating range requires EGR, the control unit 9 operates the EGR injector 1 during a period after the internal combustion engine's air intake valve is closed and before fuel injection begins, so that the EGR gas is injected into the combustion chamber.

[0039] Control unit 9 increases the fuel ignition delay by increasing the injection quantity of EGR gas. If fuel advance is necessary, control unit 9 reduces the injection quantity of EGR gas to zero.

[0040] This means that if the amount of EGR gas injected is increased, the ignition delay period of the fuel is increased.

[0041] Fig. Figure 4 is a view showing fuel ignition, wherein the injected fuel in the combustion chamber is ignited with a homogeneous level of EGR gas distribution by mixing EGR gas and intake air in a conventional combustion engine with compression ignition in advance and flowing the mixed gas into the combustion chamber and without EGR gas injection through the EGR injector 1 according to an exemplary embodiment of the invention. As in Fig. As shown in Figure 4, when fuel is injected from fuel injector 4, ignition begins near the side wall 2 of the combustion chamber.

[0042] As described above, combustion is carried out by a process in which a flame travels downwards into a central section of the combustion chamber after ignition begins near the side wall 2 of the combustion chamber.

[0043] In a state such as in Fig. 4. Since the concentrations of EGR gas are the same in a position near the side wall 2 of the combustion chamber where combustion begins and in the middle section of the combustion chamber where combustion does not begin, it is difficult to extend the ignition delay period by means of EGR gas.

[0044] This means that, in order to further extend the ignition delay period, the EGR gas should be compressed near side wall 2, where combustion begins, to delay fuel ignition. As in a conventional case where the EGR gas concentration in the combustion chamber is equal overall due to mixing the EGR gas with the intake air and the flow of the mixed gas into the combustion chamber, problems arise when the EGR gas concentration reaches a level sufficient to produce an ignition delay, namely that, in addition to the ignition delay, the fuel combustion becomes unstable.

[0045] However, in the combustion engine described above according to the invention, the control unit 9 controls the EGR injector 1 in such a way that it injects the EGR gas directly into the combustion chamber, so that the EGR gas concentration is partially compressed near the side wall 2 of the combustion chamber. When the fuel injector 4 injects fuel, the fuel is delayed due to a high EGR gas concentration near the side wall 2 of the combustion chamber, as shown in Fig. Figure 6 is shown, and fuel injection is carried out as shown in Fig. Figure 7 shows that after fuel ignition, since the flame is quickly transferred to the central section of the combustion chamber, where the EGR gas concentration is low, the desired level of the ignition delay period can be ensured, and trouble-free combustion can be carried out.

[0046] Therefore, according to an exemplary embodiment of the invention, the ignition delay period can be increased by adjusting the injection quantity of EGR gas from the EGR injector 1, advanced ignition can be achieved by reducing the injection quantity of EGR gas, and the EGR gas distribution in the combustion chamber can be finely adjusted by multiple injections of EGR gas, thus allowing fuel combustion to be controlled over a wide range. Accordingly, since the fuel-air mixture ratio is increased and stable and efficient combustion is achieved, the pollutant content of the exhaust gas can be significantly reduced, and the vehicle's fuel efficiency can be improved.

[0047] Furthermore, if a torque requested by the internal combustion engine is equal to or greater than a predetermined reference torque, the control unit 9 can control the EGR injector 1 in such a way as to reduce the amount of EGR gas injected into the combustion chamber.

[0048] This means that if the torque requested by the internal combustion engine is a high torque, which is equal to or greater than the predetermined reference torque of the internal combustion engine operating in a high load range, the control unit 9 controls the injection quantity of EGR gas to zero, and allows the internal combustion engine to operate in a state suitable for generating the torque requested by the internal combustion engine.

[0049] Accordingly, the reference torque is preferably set at a level at which it can be confirmed that the internal combustion engine enters an operating range in which the power of the internal combustion engine is prioritized over the effects resulting from the EGR gas injection through the EGR injector 1, and the reference torque can be adequately determined by carrying out a plurality of tests and analyses.

[0050] To simplify the explanation and precise definition in the accompanying claims, the terms "top", "bottom", "inside", "outside", "front", "back", etc., are used to describe features of the exemplary embodiments with respect to the positions of these features, as shown in the figures. It is further understood that the term "connect" or its variations refers to both a direct and an indirect connection.

Claims

[1] Internal combustion engine, comprising: an exhaust gas recirculation (EGR) injector (1) connected to a combustion chamber of the internal combustion engine (3) to inject EGR gas into the combustion chamber of the internal combustion engine (3); an EGR pipe (5) that connects the EGR injector (1) to an exhaust system of the internal combustion engine (3) and expels exhaust gas from the exhaust system; an EGR pump (7) which is mounted in the EGR pipe (5) and pumps the exhaust gas in the EGR pipe (5) to direct the exhaust gas to the EGR injector (1); and a control device (9) which is connected to the EGR pump (7) and the EGR injector (1) and is configured to control the EGR pump (7) and the EGR injector (1) so that the EGR injector (1) injects the EGR gas into the combustion chamber, wherein the EGR injector (1) is mounted in the combustion chamber such that a plurality of EGR gas sprays, which are injected in the direction of an inner circumference of the combustion chamber, reach the inner circumference of the combustion chamber simultaneously. [2] Internal combustion engine according to claim 1, wherein the EGR injector (1) is mounted on a top side of the combustion chamber. [3] Internal combustion engine according to one of claims 1 to 2, wherein the EGR injection nozzle (1) is mounted in a central section of the combustion chamber. [4] Internal combustion engine according to one of claims 1 to 3, wherein the control device (9) is configured to inject the EGR gas via the EGR injector nozzle (1) before fuel is injected into the internal combustion engine (3). [5] Internal combustion engine according to one of claims 1 to 4, wherein the control device (9) is configured to inject the EGR gas via the EGR injector nozzle (1) after an air inlet valve of the internal combustion engine (3) is closed. [6] Internal combustion engine according to any one of claims 1 to 5, wherein the control device (9) is configured such that it: Receives internal combustion engine operating information; using the received internal combustion engine operating information, it is determined when a current internal combustion engine operating range requires exhaust gas recirculation; and In response, the control device (9) determines that the current operating range requires exhaust gas recirculation, operates the EGR injector (1) after an air intake valve is closed and before fuel injection begins, and enables the EGR injector (1) to inject the EGR gas into the combustion chamber. [7] Internal combustion engine according to any one of claims 1 to 6, wherein the control device (9) is configured to increase the ignition delay period of fuel by increasing the injection quantity of the EGR gas. [8] Internal combustion engine according to any one of claims 1 to 7, wherein the control device (9) is configured to control the fuel ignition timing in the combustion chamber by reducing the injection quantity of the EGR gas to a predetermined injection quantity. [9] Internal combustion engine according to any one of claims 1 to 8, wherein the control device (9) is configured to control the EGR gas injection such that it is carried out at predetermined times. [10] Internal combustion engine according to any one of claims 1 to 9, wherein the control device (9) is configured such that when it determines that a torque requested by the internal combustion engine (3) is equal to or greater than a predetermined reference torque, it reduces the injection quantity of the EGR gas injected into the combustion chamber to a predetermined injection quantity. [11] Internal combustion engine according to claim 10, wherein the control device (9) is configured to reduce the injection quantity of the EGR gas injected into the combustion chamber to the predetermined injection quantity depending on an increase in the torque requested by the internal combustion engine (3). [12] Method for controlling the internal combustion engine according to any one of claims 1 to 11, wherein the method comprises: Receiving internal combustion engine operating information by the control unit (9) (S10); Determine when an instantaneous internal combustion engine operating range requires exhaust gas recirculation, using the internal combustion engine operating information received by the control unit (9) (S20); and In response to the determination that the current operating range requires exhaust gas recirculation, the EGR injector (1) is operated after an air intake valve is closed and before fuel injection begins, and the control device (9) (S30) enables the EGR injector (1) to inject the EGR gas into the combustion chamber. to determine that a torque requested by the internal combustion engine (3) is equal to or greater than a predetermined reference torque, reducing the injection quantity of the EGR gas injected into the combustion chamber to a predetermined injection quantity, by the control device (9). [13] Method according to claim 12, wherein the control device (9) is configured to increase the ignition delay period of fuel by increasing the amount of EGR gas injected. [14] Method according to claim 12 or 13, wherein the control device (9) is configured to control the fuel ignition timing in the combustion chamber by reducing the injection quantity of the EGR gas to a predetermined injection quantity. [15] Method according to claim 14, wherein the predetermined injection quantity is zero, such that the control device (9) is configured to reduce the injection quantity of the EGR gas to zero. [16] Method according to any one of claims 12 to 15, wherein the control device (9) is configured to control the EGR gas injection such that it is carried out at predetermined times. [17] Method according to claim 12, wherein the control device (9) is configured to reduce the injection quantity of the EGR gas injected into the combustion chamber to the predetermined injection quantity depending on an increase in the torque requested by the internal combustion engine (3).

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