JP2008038825A - Internal combustion engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine control device for well avoiding the worsening of combustion resulting from the back flow of exhaust gas in an internal combustion engine which has a fuel adding valve arranged in an exhaust passage near an exhaust valve. <P>SOLUTION: In an exhaust port 20 of the exhaust passage 16 for a #4 cylinder, the fuel adding valve 26 is provided for adding fuel into the exhaust passage 16. An exhaust variable valve train 58 is provided for changing a valve timing for the exhaust valve 56 (Fig.2). When an execution request for fuel addition from the fuel adding valve 26 is detected and an execution request for exhaust valve early opening control using the exhaust variable valve train 58 is detected, exhaust valve early opening control is not performed for a cylinder located close to the fuel adding valve 26. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  Conventionally, for example, Patent Document 1 discloses an exhaust particulate removal device for an internal combustion engine provided with a collecting means for collecting particulate matter in exhaust gas in an exhaust passage. This conventional apparatus includes a variable valve mechanism that can change the opening / closing timing of the exhaust valve. And the said conventional apparatus advances the valve opening timing of an exhaust valve for the purpose of reproducing | regenerating the collection capability of a collection means.

JP 2002-227630 A JP 2003-278531 A

  By the way, an internal combustion engine is known that includes a fuel addition valve that injects fuel into the exhaust passage for the purpose of heating or reducing the catalyst disposed in the exhaust passage. In the case where such a fuel addition valve is arranged in the exhaust port in the vicinity of the exhaust valve, when the advance timing of the valve opening timing of the exhaust valve is executed as in the above-described conventional device, the exhaust gas is cylindered. A situation of backflowing in can occur. If exhaust gas containing fuel added to the exhaust passage flows back into the cylinder, the combustion stability of the internal combustion engine may be impaired.

  The present invention has been made to solve the above-described problems, and in an internal combustion engine in which a fuel addition valve is disposed in an exhaust passage in the vicinity of the exhaust valve, the deterioration of combustion due to the backflow of exhaust gas is improved. An object of the present invention is to provide a control device for an internal combustion engine that can be avoided.

A first invention is a fuel addition valve that is disposed in an exhaust passage in the vicinity of an exhaust valve in at least one cylinder that is not all cylinders, and that adds fuel to the exhaust passage;
Fuel addition request detecting means for detecting a fuel addition execution request by the fuel addition valve;
A variable valve mechanism that can change the valve timing of the exhaust valve;
When the fuel addition execution request is detected, the cylinder close to the fuel addition valve is prevented from causing a backflow of exhaust gas from the exhaust passage into the cylinder in the cylinder adjacent to the fuel addition valve. Exhaust valve timing control means for controlling the valve timing of the exhaust valve so as to be valve timing independent of other cylinders;
It is characterized by providing.

Further, the second invention is the first invention, wherein the exhaust valve opening timing control means for adjusting the opening timing of the exhaust valve;
An exhaust valve early opening request detecting means for detecting an execution request for exhaust valve early opening control for advancing the opening timing of the exhaust valve;
When the fuel addition execution request is detected and the exhaust valve early opening control execution request is detected, the exhaust valve timing control means is configured to perform the exhaust for the cylinders close to the fuel addition valve. It is characterized by not performing quick valve opening control.

The third invention is the first invention, wherein the exhaust valve opening timing control means for adjusting the opening timing of the exhaust valve;
An exhaust valve early opening request detecting means for detecting an execution request for exhaust valve early opening control for advancing the opening timing of the exhaust valve;
When the fuel addition execution request is detected, and the exhaust valve early opening control execution request is detected, the exhaust valve timing control means is configured for the cylinder adjacent to the fuel addition valve to The advance amount of the opening timing of the exhaust valve is made smaller than that of the cylinder.

  According to the first aspect of the present invention, the deterioration of combustion due to the backflow of exhaust gas occurs at the time of fuel addition to the exhaust passage while minimizing the cylinder that changes the valve timing of the exhaust valve from the scheduled valve timing. Can be avoided well.

  According to the second or third invention, it is possible to satisfactorily avoid deterioration of combustion at the time of fuel addition to the exhaust passage due to the backflow of exhaust gas accompanying the rapid opening of the exhaust valve.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes a four-cycle diesel engine 10. It is assumed that the diesel engine 10 is mounted on a vehicle and used as a power source. The diesel engine 10 of the present embodiment is an in-line four-cylinder type having four cylinders # 1 to # 4, but the number of cylinders and the cylinder arrangement of the diesel engine in the present invention are not limited to this. Absent.

  Each cylinder of the diesel engine 10 is provided with an injector 12 that injects fuel directly into the cylinder. The injectors 12 of each cylinder are connected to a common common rail 14. Fuel in a fuel tank (not shown) is pressurized to a predetermined fuel pressure by a supply pump (not shown), stored in the common rail 14, and supplied from the common rail 14 to each injector 12.

  The exhaust passage 16 of the diesel engine 10 is branched by an exhaust manifold 18 and connected to an exhaust port 20 (see FIG. 2) of each cylinder. The diesel engine 10 of the present embodiment includes a turbocharger 22 with an electric motor. The exhaust passage 16 is connected to the exhaust turbine of the turbocharger 22.

  On the downstream side of the turbocharger 22 in the exhaust passage 16, an exhaust purification device 24 for purifying exhaust gas is provided. As the exhaust purification device 24, for example, one of an oxidation catalyst, a storage reduction type or selective reduction type NOx catalyst, a DPF (Diesel Particulate Filter), a DPNR (Diesel Particulate-NOx-Reduction system), or a combination thereof Etc. can be used.

  A fuel addition valve 26 for injecting fuel into the exhaust passage 16 is incorporated in the exhaust port 20 of the # 4 cylinder, that is, the exhaust passage in the vicinity of the exhaust valve 56 of the # 4 cylinder. According to such a fuel addition valve 26, unburned HC can be supplied to the catalyst in the exhaust purification device 24 when the catalyst of the exhaust purification device 24 needs to be heated or reduced.

  An air flow meter 30 for detecting the amount of intake air is installed near the inlet of the intake passage 28 of the diesel engine 10. The air taken into the intake passage 28 is compressed by the intake compressor of the turbocharger 22 and then cooled by the intercooler 32. The intake air that has passed through the intercooler 32 is distributed by the intake manifold 34 to the intake ports 35 (see FIG. 2) of the respective cylinders. In the intake passage 28, an intake throttle valve 36 is installed between the intercooler 32 and the intake manifold 34.

  One end of an external EGR passage 38 is connected to the intake passage 28 in the vicinity of the intake manifold 34. The other end of the external EGR passage 38 is connected to the vicinity of the exhaust manifold 18 of the exhaust passage 16. In the present system, a part of the exhaust gas (burned gas) can be recirculated to the intake passage 28 through the external EGR passage 38, that is, external EGR (Exhaust Gas Recirculation) can be performed.

  An EGR cooler 40 for cooling the external EGR gas is provided in the middle of the external EGR passage 38. An EGR valve 42 is provided downstream of the EGR cooler 40 in the external EGR passage 38. By changing the opening degree of the EGR valve 42, the amount of exhaust gas passing through the external EGR passage 388, that is, the amount of external EGR can be adjusted.

  An intake pressure sensor 44 that detects the intake pressure and an intake temperature sensor 46 that detects the intake air temperature are installed downstream of the intake throttle valve 36 in the intake passage 28. Further, on the upstream side of the exhaust purification device 24 in the exhaust passage 16, an air-fuel ratio sensor 48 for detecting the exhaust air-fuel ratio and an exhaust pressure sensor 50 for detecting the exhaust pressure are arranged. Further, the exhaust purification device 24 incorporates a catalyst temperature sensor 52 that detects the temperature of the catalyst inside the exhaust purification device 24.

  The system of this embodiment includes an ECU (Electronic Control Unit) 54. The ECU 54 is connected to the various sensors and actuators described above. The ECU 54 controls the operating state of the diesel engine 10 by driving each actuator according to a predetermined program based on the output of each sensor.

  FIG. 2 is a view showing a cross section of one cylinder of the diesel engine 10 in the system shown in FIG. Hereinafter, the diesel engine 10 will be further described. The diesel engine 10 includes an exhaust variable valve mechanism 58 that drives the exhaust valve 56 and an intake variable valve mechanism 62 that drives the intake valve 60. The exhaust variable valve mechanism 58 and the intake variable valve mechanism 62 are connected to the ECU 54. The specific configuration of the exhaust variable valve mechanism 58 and the intake variable valve mechanism 62 is a VVT mechanism that continuously varies the phase of a cam (not shown) that drives the exhaust valve 56 and the intake valve 60. It shall be. However, not limited to such a VVT mechanism, for example, an electromagnetically driven valve that can open and close the exhaust valve 56 and the like at an arbitrary timing may be used.

[Exhaust valve quick opening control]
In the system of this embodiment, in order to increase the exhaust temperature, the exhaust valve is quickly opened by adjusting the opening timing of the exhaust valve 56 to the advance side under a predetermined condition such as in warm air. Control may be performed. FIG. 3 is a diagram for explaining the setting of the opening timing of the exhaust valve 56 during the exhaust valve early opening control.

  A curve represented by a broken line in FIG. 3 shows the setting of the opening / closing timing of the exhaust valve 56 in a normal state, more specifically, the setting of the opening / closing timing of the exhaust valve 56 according to the operating state of the diesel engine 10. Yes. Also, the curve represented by the solid line in FIG. 3 shows the setting of the opening / closing timing of the exhaust valve 56 during the exhaust valve early opening control. That is, in this embodiment, the opening timing of the exhaust valve 56 is advanced by advancing the valve opening phase of the exhaust valve 56 by the exhaust variable valve mechanism 58.

[Characteristics of this embodiment]
The fuel addition by the fuel addition valve 26 (hereinafter sometimes simply referred to as “exhaust fuel addition”) is performed at an arbitrary timing required based on the state of the catalyst in the exhaust purification device 24. . When the exhaust valve early opening control is executed by the advance timing of the opening timing of the exhaust valve 56 under the situation where such exhaust fuel addition is being executed, in the # 4 cylinder in which the fuel addition valve 26 is arranged, The exhaust gas containing the fuel added to the exhaust port 20 may flow back into the cylinder of the # 4 cylinder. The backflow of exhaust gas containing such added fuel causes engine combustion fluctuations and increased smoke emissions.

  Therefore, in the present embodiment, for the # 4 cylinder in which the fuel addition valve 26 is arranged, when there is a request to perform exhaust fuel addition, the valve timing is not set so that the backflow of the exhaust gas occurs. The valve timing is controlled independently of the other cylinders. Specifically, when there is a request for the addition of exhaust fuel, the quick opening control of the exhaust valve 56 is not performed for the # 4 cylinder even in a situation where the request for the quick opening control of the exhaust valve is issued. I made it.

  FIG. 4 is a flowchart of a routine executed by the ECU 54 in order to realize the above function. In the routine shown in FIG. 4, first, input signal processing is executed (step 100). That is, processing of signals from various sensors included in the ECU 54 is performed.

  Next, based on the result of the input signal processing in step 100, it is determined whether there is an exhaust fuel addition execution request, more specifically, whether the catalyst of the exhaust purification device 24 needs to be heated or reduced. Is determined (step 102). As a result, when it is determined that there is no exhaust fuel addition execution request, the current processing cycle is immediately terminated thereafter.

  On the other hand, if it is determined in step 102 that there is an exhaust fuel addition execution request, it is then determined whether or not the quick opening control of the exhaust valve 56 is being performed (step 104). As a result, when it is determined that the exhaust valve early opening control is not being performed, the current processing cycle is immediately terminated thereafter.

  On the other hand, if it is determined in step 104 that the exhaust valve quick opening control is being performed, execution of the early opening control of the exhaust valve 56 is prohibited only for the # 4 cylinder in which the fuel addition valve 26 is disposed. (Step 106). Specifically, in the # 4 cylinder, the advance timing of the opening timing of the exhaust valve 56 by the exhaust variable valve mechanism 58 is not performed, and the exhaust valve early opening control is performed only in the remaining remaining cylinders.

  According to the routine shown in FIG. 4 described above, when there is a request for the exhaust valve quick opening control in a situation where an exhaust fuel addition execution request has been issued, execution of the exhaust valve quick open control in the # 4 cylinder is performed. Is prohibited. That is, for the # 4 cylinder, the valve timing of the exhaust valve 56 is controlled independently of the other cylinders so that the valve timing does not cause the exhaust gas to flow backward. For this reason, the exhaust gas containing the fuel added to the exhaust port 20 is kept in the cylinder of the # 4 cylinder while minimizing only the # 4 cylinder to change the valve timing of the exhaust valve from the scheduled valve timing. It is possible to avoid the situation of backflow. As a result, it is possible to prevent the fuel stability of the diesel engine 10 from being impaired by the presence of the exhaust gas containing such added fuel.

  By the way, in the first embodiment described above, when there is a request for the exhaust valve early opening control in a situation where an exhaust fuel addition execution request is issued, the cylinder (# 4) in which the fuel addition valve 26 is arranged (# 4). In the cylinder), the quick opening control of the exhaust valve 56 is not performed. However, in the present invention, the exhaust valve 56 is operated independently of the other cylinders in order to prevent the valve timing at which exhaust gas backflow occurs with respect to the cylinder in which the fuel addition valve 26 is disposed. The valve timing control is not limited to this. That is, the advance amount of the opening timing of the exhaust valve 56 that may cause the exhaust gas to flow back varies depending on the operating state of the diesel engine 10. For this reason, for example, if the exhaust gas backflow does not occur, even in the cylinder in which the fuel addition valve 26 is disposed, the exhaust valve early opening control is performed with the advance amount of the opening timing smaller than in the other cylinders. You may do it.

  In the first embodiment described above, the fuel addition valve 26 is arranged in the exhaust port 20 when there is a request for the exhaust valve early opening control in a situation where the request for the exhaust fuel addition is issued. For the cylinder (# 4 cylinder), the quick opening control of the exhaust valve 56 is not performed. However, as long as the fuel addition valve 26 is disposed in the exhaust passage 16 in the vicinity of the exhaust valve 56, the fuel addition valve 26 is not necessarily disposed in the exhaust port 20 adjacent to the exhaust valve 56 as described above. A backflow of exhaust gas containing can occur into the cylinder. Therefore, when the fuel addition valve 26 is arranged at a position as described below, the valve timings of the other cylinders and the exhaust valve 56 in a plurality of cylinders close to the fuel addition valve 26 as described below. May be different.

  The location of the fuel addition valve 26 will be described with reference to FIG. As described above, the exhaust passage 16 is branched into each cylinder by the exhaust manifold 18. Therefore, the portions of the exhaust passage 16 branched from each cylinder are referred to as branch pipes 18 # 1 to 18 # 4, respectively (see FIG. 1). Here, as an intake passage near the exhaust valve, a fuel addition valve 26 is provided at a connection portion (point A shown in FIG. 1) between the adjacent branch pipeline 18 # 3 and branch pipeline 18 # 4. Assume the case where it is placed. In the case of such an arrangement, the exhaust fuel addition request is required to prevent the exhaust gas from flowing back into the cylinders in a plurality of cylinders adjacent to the fuel addition valve 26, that is, the # 3 cylinder and the # 4 cylinder. When there is a request for execution of the exhaust valve rapid opening control under the situation where the is issued, the exhaust valve rapid opening control may not be performed for the # 3 cylinder and the # 4 cylinder. Alternatively, the advance amount of the exhaust valve opening timing may be made smaller than that of the other cylinders.

  In the first embodiment described above, the ECU 54 executes the process of step 102 so that the “fuel addition request detecting means” in the first invention executes the processes of steps 104 and 106. Thus, the “exhaust valve timing control means” in the first invention is realized. Further, the ECU 54 adjusts the opening timing of the exhaust valve 56 using the exhaust variable valve mechanism 58, so that the “exhaust valve opening timing control means” in the second or third invention performs the processing of step 104 above. By executing this, the “exhaust valve quick opening request detecting means” in the second or third aspect of the invention is realized.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a figure which shows the cross section of one cylinder of the diesel engine in the system shown in FIG. It is a figure for demonstrating the setting of the opening time of the exhaust valve in exhaust valve early opening control. It is a flowchart of the routine performed in Embodiment 1 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Diesel engine 12 Injector 16 Exhaust passage 18 Exhaust manifold 18 # 1- # 4 Branch pipe 20 Exhaust port 22 Turbo supercharger 24 Exhaust purification device 26 Fuel addition valve 28 Intake passage 30 Air flow meter 36 Intake throttle valve 44 Intake pressure sensor 46 Intake air temperature sensor 48 Air-fuel ratio sensor 50 Exhaust pressure sensor 52 Catalyst temperature sensor 54 ECU (Electronic Control Unit)
56 Exhaust valve 58 Exhaust variable valve mechanism

Claims (3)

A fuel addition valve that is disposed in an exhaust passage in the vicinity of the exhaust valve in at least one cylinder that is not all cylinders, and that adds fuel to the exhaust passage;
Fuel addition request detecting means for detecting a fuel addition execution request by the fuel addition valve;
A variable valve mechanism that can change the valve timing of the exhaust valve;
When the fuel addition execution request is detected, the cylinder close to the fuel addition valve is prevented from causing a backflow of exhaust gas from the exhaust passage into the cylinder in the cylinder adjacent to the fuel addition valve. Exhaust valve timing control means for controlling the valve timing of the exhaust valve so as to be valve timing independent of other cylinders;
A control device for an internal combustion engine, comprising: Exhaust valve opening timing control means for adjusting the opening timing of the exhaust valve;
An exhaust valve early opening request detecting means for detecting an execution request for exhaust valve early opening control for advancing the opening timing of the exhaust valve;
When the fuel addition execution request is detected and the exhaust valve early opening control execution request is detected, the exhaust valve timing control means is configured to perform the exhaust for the cylinders close to the fuel addition valve. 2. The control device for an internal combustion engine according to claim 1, wherein quick valve opening control is not performed. Exhaust valve opening timing control means for adjusting the opening timing of the exhaust valve;
An exhaust valve early opening request detecting means for detecting an execution request for exhaust valve early opening control for advancing the opening timing of the exhaust valve;
When the fuel addition execution request is detected, and the exhaust valve early opening control execution request is detected, the exhaust valve timing control means is configured for the cylinder adjacent to the fuel addition valve to 2. The control device for an internal combustion engine according to claim 1, wherein an advance amount of the opening timing of the exhaust valve is made smaller than that of the cylinder.

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