JP4600316B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine that can be operated with a reformed fuel produced by reforming a predetermined fuel such as a hydrocarbon-based fuel.

  In general, in an internal combustion engine, in many cases, the exhaust purification device does not reach the activation temperature when the engine is cold, such as when the engine is started, so harmful components such as HC components in the exhaust gas are removed during operation with hydrocarbon fuel. It cannot be purified with an exhaust purification device.

  Therefore, conventionally, as disclosed in, for example, Patent Document 1 below, some of the cylinders are richly burned at the time of engine start, while the other cylinders are lean burned, so that A technique is known in which unburned hydrocarbon fuel and air in the exhaust gas of a lean combustion cylinder are combusted by an exhaust port or an exhaust purification device, thereby increasing the catalyst carrier temperature of the exhaust purification device early.

  For example, as disclosed in Patent Document 2 below, the reformed gas generated from the predetermined fuel by the fuel reformer is supplied to the combustion chamber when the engine is started, and is operated with the reformed gas. An internal combustion engine that reduces harmful components in exhaust gas is known.

  Further, in Patent Document 3 below, in order to efficiently desorb and purify NOx trapped in the NOx trap catalyst of the exhaust system with hydrogen gas, the hydrogen gas in the hydrogen tank is supplied to the exhaust passage and the NOx trap catalyst is supplied. A technique for sending to a device is disclosed.

Japanese Patent Laid-Open No. 9-236033 JP 2004-251273 A JP 2002-180824 A

  However, in the technique disclosed in Patent Document 1, even if a large amount of unburned HC component is discharged from the rich combustion cylinder by such control, even if the time until the exhaust purification device is activated is shortened. In the meantime, a larger amount of harmful components are released to the atmosphere than when such control is not performed, and the emission performance is greatly deteriorated.

  Therefore, an object of the present invention is to provide an internal combustion engine that improves the disadvantages of the conventional example and activates the exhaust purification device at an early stage while suppressing the deterioration of the emission performance.

  In order to achieve the above object, according to the first aspect of the present invention, in an internal combustion engine having a plurality of cylinders that can be operated using a reformed gas generated from a predetermined fuel by a fuel reformer as a fuel, Control means for stopping the ignition operation for some of the cylinders is provided.

  In the internal combustion engine according to the first aspect, the air-fuel mixture of the reformed gas and air is directly discharged to the exhaust path from the cylinder whose ignition operation has been stopped. For this reason, in this exhaust path, the reformed gas (hydrogen gas and carbon monoxide gas) and oxygen in the air cause a combustion reaction in the exhaust port, the exhaust manifold or the exhaust purification device. Further, the carbon monoxide gas in the reformed gas causes a catalytic reaction in the exhaust purification device. Therefore, in the exhaust gas purification device, the catalyst carrier temperature is increased early by the inflow of exhaust gas that has increased in temperature due to the combustion reaction at the exhaust port or the like, or the direct combustion reaction at the catalyst carrier or the catalytic reaction of carbon monoxide gas. To rise.

  In order to achieve the above object, in the invention according to claim 2, in the internal combustion engine according to claim 1, the fuel reformer is configured so that the supply amount of the generated reformed gas can be adjusted for each cylinder, The control means is configured to control the fuel reformer so that the supply amount of the reformed gas to the cylinder for stopping the ignition operation is larger than that of the other cylinders.

  In the internal combustion engine according to claim 2, since a larger amount of reformed gas is discharged onto the exhaust path to cause a combustion reaction or a catalytic reaction, the exhaust purification device is raised to the activation temperature more efficiently and earlier. Can be made.

  In order to achieve the above object, according to a third aspect of the present invention, in an internal combustion engine having a plurality of cylinders operable with a reformed gas generated from a predetermined fuel by a fuel reformer as a fuel, Control means is provided for controlling the mixture of reformed gas and air to some cylinders of the cylinders to the rich side with respect to the mixture of other cylinders.

  In the internal combustion engine according to the third aspect, the reformed gas that could not be combusted from the over-concentrated cylinder is directly discharged to the exhaust path. Therefore, in this exhaust path, the reformed gas (hydrogen gas and carbon monoxide gas) causes a combustion reaction or a catalytic reaction. Therefore, also in the exhaust gas purification apparatus according to the third aspect, the catalyst carrier temperature can be raised early as in the exhaust gas purification apparatus according to the first aspect.

  For example, as in the invention according to claim 4, in the internal combustion engine according to claim 3, the fuel reformer is configured so that the supply amount of the generated reformed gas can be adjusted for each cylinder. The fuel reformer is controlled so that the amount of reformed gas supplied to the cylinders to be increased is larger than that of the other cylinders.

  Here, as in the invention described in claim 5, the control means controls the air-fuel mixture of other cylinders other than the cylinder to be enriched to the lean side in the internal combustion engine described in claim 3 or 4. It is preferable to configure as described above.

  According to the internal combustion engine of the fifth aspect, since oxygen is present in the exhaust gas from the other cylinders, the combustion reaction and catalytic reaction of the reformed gas can be promoted using this oxygen. .

  The internal combustion engine according to the present invention can supply the reformed gas upstream of the exhaust gas purification device on the exhaust path, and therefore, the catalyst carrier of the exhaust gas purification device utilizing the combustion reaction or catalytic reaction of the reformed gas. The temperature can be raised. For this reason, according to this internal combustion engine, the temperature of the catalyst carrier can be raised faster than the temperature of the catalyst carrier can be raised only by the exhaust gas, so that the exhaust purification device can be activated early. Further, at that time, the reformed gas is sent to the exhaust path, but since the HC component is hardly present in the reformed gas, the emission performance is not deteriorated. Therefore, in the internal combustion engine according to the present invention, combustion with a hydrocarbon-based fuel can be performed while ensuring emission performance from an early stage, and therefore, optimal combustion control according to desired operating conditions and the like is executed. Will be able to.

  Embodiments of an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

  A first embodiment of an internal combustion engine according to the present invention will be described with reference to FIGS.

  Reference numeral 1 in FIG. 1 indicates the internal combustion engine of the first embodiment. The internal combustion engine 1 includes an engine body 10 having first to fourth cylinders 11a to 11d, an intake passage 20 for supplying air from the outside to the combustion chambers of the first to fourth cylinders 11a to 11d, First to fourth fuel injectors 30a to 30d for injecting fuels to be burned in the respective combustion chambers (here, hydrocarbon-based fuels such as gasoline) and exhaust gases discharged from the respective combustion chambers An exhaust path 40 that discharges the air to the atmosphere, and a fuel reformer 50 that generates reformed fuel and supplies the reformed fuel to the intake path 20.

  First, in the intake passage 20 of the internal combustion engine 1 of the first embodiment, an intake passage 21 for sucking and guiding air from the outside, an air cleaner 22 for removing foreign matters such as dust from the introduced air, and an intake from the outside An air flow meter 23 for detecting the amount of air; a throttle valve 24 for adjusting the amount of intake air into the combustion chambers of the first to fourth cylinders 11a to 11d; a throttle valve actuator 25 for driving the throttle valve 24 to open and close; A throttle opening sensor 26 that detects the opening of the throttle valve 24 and an intake manifold 27 that guides the air adjusted by the throttle valve 24 to the combustion chambers of the first to fourth cylinders 11a to 11d are provided. ing.

  Here, detection signals from the air flow meter 23 and the throttle opening sensor 26 are transmitted to an electronic control unit (ECU) 60 serving as a control means. Therefore, in this electronic control unit 60, the amount of intake air from the outside is calculated based on the detection signal of the air flow meter 23, and the opening degree of the throttle valve 24 is detected based on the detection signal of the throttle opening degree sensor 26. .

  Further, the electronic control device 60 issues a control command for the valve opening angle of the throttle valve 24 to the throttle valve actuator 25, and supplies a desired amount of air according to the valve opening angle to the first to fourth cylinders 11a. The throttle valve 24 is driven to open and close to be sucked into the combustion chamber of ˜11d.

  In the first embodiment, the first to fourth fuel injection devices 30a to 30d described above are disposed in the intake ports of the first to fourth cylinders 11a to 11d in the engine body 10, respectively. . For this reason, in the internal combustion engine 1, the fuel in each intake port injected from the first to fourth fuel injection devices 30a to 30d together with air enters the combustion chambers of the first to fourth cylinders 11a to 11d. After being inhaled, the respective air-fuel mixtures are ignited from the first to fourth spark plugs 12a to 12d. Here, the electronic control unit 60 of the first embodiment controls the fuel injection timings of the first to fourth fuel injection devices 30a to 30d and the ignition timings of the first to fourth spark plugs 12a to 12d. To control. The first to fourth fuel injection devices 30a to 30d may be arranged to inject fuel directly into the combustion chambers of the first to fourth cylinders 11a to 11d, respectively.

  In the internal combustion engine 1, the in-cylinder gas after ignition is discharged to the exhaust path 40 through the exhaust ports of the first to fourth cylinders 11 a to 11 d in the engine body 10.

  The exhaust path 40 of the first embodiment includes an exhaust manifold 41 that collects exhaust gases discharged to the respective exhaust ports into one path, and an exhaust purification device 42 such as a three-way catalyst that purifies harmful components in the exhaust gas. And.

By the way, in general, in an internal combustion engine, by using hydrogen as a fuel at the time of combustion, a CO (carbon monoxide) component, a CO ₂ (carbon dioxide) component, It is known that harmful components such as HC (hydrocarbon) components can be greatly reduced. Therefore, in a situation where it is difficult to purify the harmful components in the exhaust gas because the catalyst carrier temperature of the exhaust purification device 42 does not reach the activation temperature, the exhaust of the harmful components itself can be suppressed by hydrogen. Combustion is effective in improving emission performance. Such a situation is typically when the engine is cold, such as when the engine is started, but when the exhaust purification device 42 once activated becomes lower than the activation temperature due to, for example, a light load operation or the like. Is also included.

  Therefore, in the first embodiment, hydrogen gas as reformed fuel is generated by the fuel reformer 50 described above in a state where the exhaust purification device 42 is not activated, and this is used as fuel during combustion. To be able to operate. In the first embodiment, hydrogen gas is generated by reforming the hydrocarbon fuel. The fuel reformer 50 can be constructed by a well-known configuration in the technical field. For example, in the first embodiment, a mixture of hydrocarbon fuel and oxygen is used as hydrogen gas and carbon monoxide gas. A fuel reforming apparatus 50 having the following configuration is applied to reformed gas mainly composed of gas and supplied to the intake passage 20. Hereinafter, the fuel reformer 50 of the first embodiment will be described in detail.

  The fuel reformer 50 according to the first embodiment includes a mixing unit 51a that mixes a hydrocarbon-based fuel and air (oxygen) and a reforming reaction between the mixture of the hydrocarbon-based fuel and air (oxygen) to generate hydrogen gas. And a fuel reforming catalyst 51b that generates a reformed gas mainly composed of carbon monoxide gas. Here, the fuel reforming catalyst 51b is an electrically heated reforming catalyst provided with heating means (not shown) such as a heater, and is reformed after being heated to a predetermined temperature at which a reforming reaction is possible. Start producing gas.

  The fuel reformer 50 is provided with a fuel supply means 52 for supplying hydrocarbon fuel to the mixing portion 51a. As the fuel supply means 52, for example, a so-called fuel injection valve for injecting hydrocarbon-based fuel into the mixing portion 51a is used. The operation of the fuel supply means 52 is controlled by the electronic control device 60 when the fuel reforming catalyst 51b reaches a predetermined reforming reaction temperature, and the fuel is supplied at a supply amount corresponding to the amount of reformed gas generated. Let spray.

  Furthermore, the fuel reformer 50 is provided with an air supply means 53 for supplying air to the mixing portion 51a. As the air supply means 53 of the first embodiment, a diversion passage for diverting the air in the intake passage 21 and leading it to the mixing unit 51a is used. In the first embodiment, the air supply means 53 is configured by arranging a diversion passage so that the upstream side of the throttle valve 24 on the intake passage 21 communicates with the mixing portion 51a. The air supply means 53 includes a pump that pumps air, an air supply path that guides the air discharged from the pump to the mixing unit 51a, and an air supply that is provided on the air supply path to supply the mixing unit 51a. An air supply amount adjusting valve that adjusts the amount may be configured. In this case, the pump and the air supply amount adjusting valve are controlled by the electronic control unit 60 and supplied according to the generation amount of the reformed gas. An amount of air is supplied to the mixing unit 51a.

  Further, the fuel reformer 50 includes a reformed gas supply path 54 that guides the reformed gas generated by the fuel reforming means 51 to the intake path 20, and an inflow amount of the reformed gas into the intake path 20. And a reformed gas flow rate adjusting means 55 for adjusting. The reformed gas supply path 54 communicates with the downstream side of the throttle valve 24 on the intake path 20. In the first embodiment, one end of the reformed gas supply path 54 is communicated so that the reformed gas is supplied to the assembly portion of the intake manifold 27. Further, as the reformed gas flow rate adjusting means 55, for example, the communication state between the reformed gas supply path 54 and the intake path 20 can be changed steplessly from a fully closed state to a fully opened state according to an instruction from the electronic control unit 60, A reformed gas flow rate control valve that can be varied in stages and can appropriately adjust the inflow amount of the reformed gas is used. As the reformed gas flow rate control means 55, an open / close valve that can switch between the reformed gas supply path 54 and the intake path 20 between a fully closed state and a fully opened state may be used.

  In the internal combustion engine 1 of the first embodiment having such a configuration, the fuel reforming device 50 is operated and operated with the reformed gas, whereby harmful components in the exhaust gas can be greatly reduced. . Therefore, in a situation where the exhaust purification device 42 is not activated, good emission performance can be ensured by executing the operation with the reformed gas.

  Here, even under such circumstances, for example, depending on driving conditions such as athletic performance desired by the driver and driving environment, it may be preferable to operate with a hydrocarbon-based fuel rather than driving with reformed gas. . However, in recent years, exhaust gas regulations tend to be tightened every year. Under such circumstances, it is not desirable to operate with hydrocarbon fuels until the emission performance is sacrificed. On the other hand, it is not preferable to continue to operate with reformed gas even though operation with hydrocarbon fuel is desired. This situation is resolved quickly and operation with hydrocarbon fuel as soon as possible. It is desirable to make it.

  Further, if the hydrocarbon-based fuel remains without being reformed by the fuel reformer 50, the unreformed fuel is burned in the combustion chamber to generate harmful components. For this reason, when unreformed fuel is generated in a state where the exhaust purification device 42 is not activated, the harmful components generated by the combustion cannot be purified by the exhaust purification device 42 and the emission performance is improved. It gets worse.

  Therefore, in the first embodiment, in order to activate the exhaust purification device 42 at an early stage, the reformed gas is supplied to the upstream side of the exhaust purification device 42 on the exhaust path 40 and burned, and the combustion is performed. The catalyst carrier temperature of the exhaust gas purification device 42 is raised using the heat generated by the reaction. The warm-up control of the exhaust purification device 42 is executed by the electronic control device 60.

  Specifically, the electronic control unit 60 according to the first embodiment stops the ignition operation of some cylinders (at least one of the first to fourth cylinders 11a to 11d) and stops the ignition operation. The mixture of reformed gas and air sucked into the exhaust gas is discharged to the exhaust passage 40 as it is. In the internal combustion engine 1 of the first embodiment, when performing the warm-up control, hydrocarbon fuel is not injected from the first to fourth fuel injection devices 30a to 30d, and only the reformed gas is used as fuel. To drive.

  Here, the electronic control device 60 of the first embodiment starts the warm-up control of the exhaust purification device 42 when it matches a predetermined condition (hereinafter referred to as “warm-up control execution condition”). Various conditions can be considered as the warm-up control execution conditions.

  For example, in order to execute the warm-up control of the exhaust purification device 42 (combusting the reformed gas in the exhaust path 40), it is necessary to use the exhaust heat, and know whether or not the internal combustion engine 1 is started. Thus, the presence or absence of exhaust heat can be grasped. Therefore, in the first embodiment, the start of the internal combustion engine 1 is set as the warm-up control execution condition. This engine start can be determined from the ignition instruction signal of the electronic control unit 60 or the like. In the first embodiment, by setting this engine start as the warm-up control execution condition, the reformed gas on the exhaust path 40 can be surely burned without being released to the atmosphere. It is possible to activate the exhaust purification device 42 with good quality early. Further, since the carbon monoxide gas in the reformed gas can be prevented from being released to the atmosphere, it is not necessary to deteriorate the emission performance.

  By the way, when focusing on the exhaust heat as a requirement for starting the engine, whether or not the engine is started can be grasped from the temperature change of the exhaust heat. A change in temperature of the exhaust temperature detected from the sensor 43 (which may be the number of ignitions that can be estimated or an integrated intake air amount, etc.) may be used as the warm-up control execution condition. That is, the electronic control unit 60 can determine that the engine has been started when the exhaust gas temperature has changed to a high temperature side. For example, when the temperature change exceeds a predetermined numerical value (threshold value), the exhaust gas purification device 42 warm-up control may be executed. The threshold value varies depending on the water temperature, the outside air temperature, and the like, and is set in advance through experiments and simulations that take these parameters into account.

  Furthermore, if the exhaust gas temperature can be grasped, the catalyst carrier temperature of the exhaust gas purification device 42 can be estimated. For example, the electronic control device 60 has a predetermined exhaust gas whose exhaust temperature corresponds to the activation temperature of the exhaust gas purification device 42. When the temperature is lower than the threshold value (threshold), the warm-up control of the exhaust purification device 42 may be executed. As a result, unnecessary control does not have to be performed at the time of restart or the like when the exhaust purification device 42 has already reached the activation temperature. Here, the electronic control unit 60 directly detects the catalyst carrier temperature of the exhaust purification device 42 from a detection signal of a temperature sensor (not shown), and performs warm-up control of the exhaust purification device 42 when this is lower than the activation temperature. It may be executed.

  Further, the electronic control device 60 of the first embodiment terminates the warm-up control of the exhaust purification device 42 when it matches a predetermined condition (hereinafter referred to as “warm-up control end condition”). The warm-up control end condition includes the exhaust temperature detected when the catalyst carrier temperature of the exhaust purification device 42 reaches the activation temperature, or the exhaust temperature detected from the exhaust temperature sensor 43 (the number of ignitions that can be estimated, the integrated intake air amount, etc. Is set to a value equal to or higher than a predetermined exhaust gas temperature (threshold value) corresponding to the activation temperature of the exhaust purification device 42. As a result, the combustion reaction or catalytic reaction of the reformed gas does not occur more than necessary on the exhaust path 40, so that deterioration or failure due to overheating of the exhaust purification device 42 can be prevented. Here, the threshold value varies depending on the water temperature, the outside air temperature, and the like as in the warm-up control execution condition, and is set in advance through experiments and simulations that take these parameters into consideration.

  Next, the operation of the internal combustion engine 1 of the first embodiment will be described based on the flowchart of FIG.

  First, the electronic control device 60 according to the first embodiment determines whether or not the exhaust gas purification device 42 is in a warm-up control execution condition (step ST1).

  Here, when the electronic control unit 60 determines that it is the warm-up control execution condition, the electronic control unit 60 operates the fuel reformer 50 to generate reformed gas and supplies it to the intake path 20 ( Step ST2). Specifically, at that time, the electronic control unit 60 operates the heating means to heat the fuel reforming catalyst 51b, and the reforming is performed when the reforming catalyst carrier temperature becomes equal to or higher than a predetermined temperature at which the reforming reaction is possible. The gas flow rate adjusting means 55 is opened and the fuel supply means 52 is driven. As a result, in the fuel reformer 50, the hydrocarbon-based fuel and air are supplied to the mixing unit 51a, and the mixture is sent to the fuel reforming catalyst 51b to mainly contain hydrogen gas and carbon monoxide gas. A reformed gas is generated. Then, the reformed gas is supplied to the collective portion of the intake manifold 27 via the reformed gas supply path 54.

  Subsequently, the electronic control unit 60 performs control so that the mixture of the reformed gas and the air on the intake path 20 has a lean air-fuel ratio (step ST3). The air-fuel mixture may be controlled to a preset lean air-fuel ratio, or may be controlled to a lean air-fuel ratio that is appropriately set according to the operating state or the like. Here, in step ST3, the air-fuel ratio is adjusted to a desired air-fuel ratio by driving and controlling either or both of the throttle valve actuator 25 and the reformed gas flow rate adjusting means 55. In the first embodiment, since the flow rate of the reformed gas is already set by the drive control of the reformed gas flow rate adjusting means 55 in the above step ST2, the flow rate of the reformed gas is set in the step ST2. May be used as they are (that is, it is not necessary to drive and control the reformed gas flow rate adjusting means 55 in step ST3), or may be newly set in step ST3.

  By diluting the air-fuel mixture sucked into the first to fourth cylinders 11a to 11d in this way, the amount of oxygen on the exhaust path 40 is increased, and the subsequent combustion reaction of the reformed gas is promoted. In step ST3, it is most preferable to dilute the air-fuel mixture as described above. However, for the air-fuel mixture, the stoichiometric air-fuel ratio can be reduced from a stoichiometric air-fuel ratio that can suppress an excess of reformed gas on the exhaust passage 40. As long as it is between, you may control any.

  After generating the lean air-fuel mixture in this way, the electronic control unit 60 stops the ignition operation of some of the first to fourth cylinders 11a to 11d (step ST4). Here, the ignition operation of one of the first to fourth cylinders 11a to 11d is stopped.

  As a result, the air-fuel mixture of the introduced reformed gas and air is directly discharged to the exhaust path 40 from the cylinder whose ignition operation is stopped, and the reformed gas (hydrogen gas and carbon monoxide gas) is exhausted in the exhaust path 40. And oxygen in the air causes a combustion reaction in the exhaust port, the exhaust manifold 41 or the exhaust purification device 42. Here, the hydrogen gas in the reformed gas has a wide flammable range and is easily ignited. Further, the carbon monoxide gas in the reformed gas burns in the presence of oxygen, and at the low temperature, a catalytic reaction starts in the exhaust purification device 42 and is purified to carbon dioxide. Accordingly, in the exhaust purification device 42, the catalyst carrier temperature is increased early by the inflow of exhaust gas that has increased in temperature due to the combustion reaction at the exhaust port or the like, the direct combustion reaction at the catalyst carrier, or the catalytic reaction of carbon monoxide gas. To rise.

  Subsequently, the electronic control unit 60 determines whether or not a condition for ending the warm-up control of the exhaust purification device 42 is satisfied (step ST5).

  If the warm-up control end condition is not satisfied, the process returns to step ST3 to continue the warm-up control. If the warm-up control end condition is satisfied, the air-fuel ratio of the air-fuel ratio set in steps ST3 and ST4 The ignition timings of the fourth cylinders 11a to 11d are reset (step ST6) and switched to normal air-fuel ratio control and ignition control (step ST7).

  Here, when the electronic control unit 60 determines in step ST1 that the condition is not the warm-up control execution condition, the electronic control unit 60 proceeds to step ST7 and executes normal air-fuel ratio control and ignition control.

  As described above, according to the internal combustion engine 1 of the first embodiment, the reforming gas is supplied onto the exhaust path 40 by stopping the ignition operation of some cylinders, and the reforming is performed on the exhaust path 40. Gas is subjected to combustion reaction or catalytic reaction. For this reason, in the internal combustion engine 1, the temperature of the catalyst carrier of the exhaust purification device 42 can be increased faster than when the temperature is increased only with the exhaust gas, so that the exhaust purification device 42 can be activated early. Further, at that time, the reformed gas is sent to the exhaust passage 40, but since the HC component is hardly present in the reformed gas, the emission performance is not deteriorated. Therefore, in the internal combustion engine 1, combustion with a hydrocarbon fuel can be performed while ensuring emission performance from an early stage, so that optimum combustion control according to desired operating conditions can be executed. become.

  By the way, if the ignition operation of only a specific cylinder is continuously stopped, the warm-up of the cylinder is delayed with respect to the other cylinders. Therefore, in that cylinder, the warm-up is insufficient after the warm-up control of the exhaust purification device 42 is finished. There is a risk that a combustion failure or the like may occur. Further, in this internal combustion engine 1, since ignition is not performed only in a specific cylinder, there is a possibility that torque fluctuations occur.

  Therefore, the ignition operation stop cylinders during the warm-up control of the exhaust purification device 42 are changed at predetermined intervals (for example, every cycle). It is desirable to change the ignition operation stop cylinder in a balanced order in which torque fluctuation or the like cannot occur in consideration of the ignition order at the time of normal ignition control.

  As a result, the entire engine is warmed up evenly, and therefore, there is no cylinder causing combustion failure and the like, and torque fluctuations can be suppressed. Further, since the combustion reaction in the exhaust port and the branch passage of the exhaust manifold 41 is performed uniformly in each of the cylinders 11a to 11d, the exhaust port and the like can be warmed up evenly. Further, even if there is a deviation in the flow location of each exhaust gas flowing through the exhaust purification device 42 discharged from each cylinder 11a to 11d, the exhaust purification device 42 can be warmed up evenly. .

  Here, the warm-up control of the exhaust emission control device 42 of the first embodiment can be applied not only to the above-described internal combustion engine 1 of FIG. 1 but also to, for example, the internal combustion engine 100 shown in FIG.

  The internal combustion engine 100 of FIG. 3 is obtained by changing the above-described fuel reformer 50 to the fuel reformer 150 shown in FIG. 3 in the internal combustion engine 1 of FIG. 1 is configured.

  The fuel reformer 150 shown in FIG. 3 includes a fuel reforming means 51 having a mixing section 51a and a fuel reforming catalyst 51b similar to the fuel reformer 50 described above, a fuel supply means 52, and an air supply means 53. And. Therefore, also in this fuel reformer 150, the reforming reaction of the hydrocarbon-based fuel and air is performed to generate a reformed gas mainly composed of hydrogen gas and carbon monoxide gas.

  On the other hand, in the fuel reformer 150, the reformed gas generated by the fuel reforming means 51 is supplied to the intake manifold 27 so that the reformed gas is individually supplied to the first to fourth cylinders 11a to 11d. The first to fourth reformed gas supply passages 54a to 54d led to the branch flow passages of the first to fourth cylinders 11a to 11d, and the first to fourth reformed gas supply passages 54a to 54d, respectively. First to fourth reformed gas flow rate adjusting means 55a to 55d for adjusting the inflow amount of the reformed gas are provided. As the first to fourth reformed gas flow rate adjusting means 55a to 55d, similarly to the reformed gas flow rate adjusting means 55 of FIG. 1, a reformed gas flow rate adjusting valve or a fully closed state and a fully open state can be switched. Use an open / close valve.

  Also in the internal combustion engine 100 configured as described above, the same amount of reformed gas is supplied from the first to fourth reformed gas supply paths 54a to 54d, and the same control as that of the internal combustion engine 1 of FIG. By executing, the same effect as that of the internal combustion engine 1 can be obtained.

  In the internal combustion engine 100, the supply amount of the reformed gas to the ignition operation stop cylinder may be increased according to the amount of oxygen that may exist on the exhaust path 40. As a result, a larger amount of the reformed gas causes a combustion reaction or a catalytic reaction on the exhaust path 40, so that the exhaust purification device 42 can be raised to the activation temperature more efficiently and earlier.

  Next, a second embodiment of the internal combustion engine according to the present invention will be described with reference to FIGS.

  In the second embodiment, the method of supplying the reformed gas to the exhaust path 40 in the internal combustion engine 100 of FIG. 3 illustrated in the first embodiment is changed. In the second embodiment, the electronic control device 60 is supplied with a mixture of reformed gas and air to some cylinders (at least one of the first to fourth cylinders 11a to 11d). Control is performed on the rich side of the air-fuel mixture in the cylinder, and the reformed gas in the cylinder to which the rich air-fuel mixture is supplied is not combusted in the combustion chamber and is discharged to the exhaust passage 40 as it is.

  Specifically, in the electronic control unit 60 according to the second embodiment, the amount of reformed gas supplied to some cylinders is increased relative to the other cylinders, thereby mixing the some cylinders. Set Qi to the over-rich side with respect to the other cylinders. An amount of the reformed gas that remains without being burned in the combustion chamber is supplied to some of the cylinders.

  The operation of the internal combustion engine 100 of the second embodiment will be described based on the flowchart of FIG.

  First, the electronic control unit 60 according to the second embodiment determines whether or not the condition for executing the warm-up control of the exhaust purification device 42 is the same as in the first embodiment (step ST11).

  Here, the electronic control unit 60 proceeds to the following step ST16 to execute normal air-fuel ratio control and ignition control unless the warm-up control execution condition is satisfied. Similarly, the fuel reformer 150 is operated to generate reformed gas (step ST12).

  Subsequently, the electronic control unit 60 controls the air-fuel mixture to some cylinders among the first to fourth cylinders 11a to 11d to be richer than the air-fuel mixture of other cylinders (step ST13). ). Here, the air-fuel mixture of one cylinder among the first to fourth cylinders 11a to 11d is excessively enriched. For example, the electronic control unit 60 at that time makes the valve opening amount of the first reformed gas flow rate adjusting means 55a larger than the valve opening amounts of the remaining second to fourth reformed gas flow rate adjusting means 55b to 55d. The supply amount of the reformed gas to the first cylinder 11a is increased with respect to the supply amounts to the remaining second to fourth cylinders 11b to 11d. At this time, when the air-fuel mixture sucked into the second to fourth cylinders 11b to 11d becomes the rich air / fuel ratio or the stoichiometric air / fuel ratio, the electronic control unit 60 uses the second to fourth cylinders 11b. The valve opening amounts of the second to fourth reformed gas flow rate adjusting means 55b to 55d are reduced so that the air-fuel mixture of .about.11d becomes a lean air-fuel ratio.

  Thereby, in the cylinder to be controlled (first cylinder 11a), a part of the reformed gas remains without being combusted and is directly discharged to the exhaust path 40. On the other hand, in the remaining cylinders (second to fourth cylinders 11b to 11d) that have ignited the lean air-fuel ratio mixture, oxygen remains in the exhaust gas discharged to the exhaust passage 40. Yes. Therefore, also in the exhaust purification device 42 of the second embodiment, the combustion reaction of unburned reformed gas (hydrogen gas and carbon monoxide gas) downstream of the aggregated portion of the exhaust manifold 41 and the catalyst for carbon monoxide gas. The catalyst support temperature rises early due to the reaction.

  Next, the electronic control unit 60 determines whether or not the warm-up control end condition of the exhaust purification device 42 is satisfied as in the first embodiment (step ST14).

  If the warm-up control end condition is not satisfied, the process returns to step ST13 to continue the warm-up control. If the warm-up control end condition is satisfied, the first to fourth cylinders 11a to 11d set in step ST13 are set. The air-fuel ratio of each air-fuel mixture is reset (step ST15), switching to normal air-fuel ratio control, and normal air-fuel ratio control and ignition control are executed (step ST16).

  As described above, according to the internal combustion engine 100 of the second embodiment, the reformed gas is supplied onto the exhaust path 40 by over-concentrating the air-fuel mixture of some cylinders, and on the exhaust path 40 The reformed gas is subjected to a combustion reaction or a catalytic reaction. Therefore, in the internal combustion engine 100 as well, as with the internal combustion engine 1 of the first embodiment, the catalyst carrier temperature of the exhaust purification device 42 can be raised faster than when the temperature is increased only with the exhaust gas. Early activation of the device 42 can be achieved. Further, since almost no HC component is present in the reformed gas on the exhaust path 40, the emission performance is not deteriorated. Accordingly, even in the internal combustion engine 100 of the second embodiment, combustion with a hydrocarbon-based fuel can be performed while ensuring the emission performance from an early stage, so optimal combustion control according to desired operating conditions is executed. Will be able to.

  By the way, if the air-fuel mixture is excessively enriched only for a specific cylinder, the warm-up speed differs between that cylinder and the remaining cylinders, and after the warm-up control of the exhaust purification device 42 is finished. Thus, there is a risk of combustion failure or the like occurring in a cylinder that is not warmed up. Further, in this internal combustion engine 100, since the air-fuel mixture is excessively concentrated in other cylinders than in other cylinders, there is a risk that torque fluctuation will occur.

  Accordingly, the cylinders subject to over-concentration control during execution of warm-up control of the exhaust purification device 42 are changed at predetermined intervals (for example, every cycle). It is desirable that the over-concentration control target cylinders are changed in a balanced order where torque fluctuation or the like cannot occur.

  As a result, the entire engine is warmed up evenly, and therefore, there is no cylinder causing combustion failure and the like, and torque fluctuations can be suppressed. Further, the exhaust port and the branch passage of the exhaust manifold 41 can be warmed up evenly. Further, even if there is a deviation in the flow location of each exhaust gas flowing through the exhaust purification device 42 discharged from each cylinder 11a to 11d, the exhaust purification device 42 can be warmed up evenly. .

  Here, a configuration capable of controlling the intake air amount for each of the cylinders 11a to 11d (for example, a flow rate control valve capable of adjusting the intake amount of air for each of the cylinders 11a to 11d, variable valve timing / valve lift amount of the intake valve) If an adjustment mechanism or the like is provided, the air-fuel ratio of the air-fuel mixture of each of the cylinders 11a to 11d may be adjusted as described above by controlling the configuration by the electronic control unit 60.

  Further, in the second embodiment, in order to supply oxygen to be reacted with the reformed gas onto the exhaust path 40, the air-fuel mixture of the remaining cylinders other than the over-concentration control target cylinder is diluted. However, it is not always necessary to dilute the air-fuel mixture for the remaining cylinders. For example, oxygen supply means for supplying oxygen to the upstream side of the exhaust purification device 42 on the exhaust path 40 may be provided. For example, as the oxygen supply means, a so-called secondary air supply device or the like can be considered. When such an oxygen supply means is provided, the same effect can be obtained even if only a part of the cylinders is excessively concentrated as described above, but the air-fuel mixture of all the cylinders 11a to 11d can be obtained. Since a larger amount of the reformed gas can be reacted by the overconcentration, the activation of the exhaust purification device 42 can be realized at an earlier stage.

  In each of the first and second embodiments described above, the internal combustion engine 1 and 100 having four cylinders 11a to 11d has been described as an example. However, the internal combustion engine according to the present invention has a plurality of cylinders. Any of them can be applied.

  Further, in each of the first and second embodiments described above, a fuel reformer 50 that reforms a mixture of hydrocarbon fuel and oxygen to generate a reformed gas mainly composed of hydrogen gas and carbon monoxide gas. , 150, the fuel reformers 50, 150 are configured to generate a reformed gas mainly composed of hydrogen gas and carbon monoxide gas from a mixture of hydrocarbon fuel and oxygen and water vapor. May be.

  As described above, the internal combustion engine according to the present invention is suitable for a technique for activating the exhaust purification device at an early stage while suppressing deterioration of emission performance.

1 is a diagram illustrating a configuration of a first embodiment of an internal combustion engine according to the present invention. FIG. 3 is a flowchart for explaining the operation of the internal combustion engine of the first embodiment. It is a figure which shows the structure of Example 1, 2 of the internal combustion engine which concerns on this invention. 6 is a flowchart illustrating an operation of the internal combustion engine of the second embodiment.

Explanation of symbols

1,100 Internal combustion engines 11a to 11d First to fourth cylinders 12a to 12d First to fourth spark plugs 20 Intake passage 21 Intake passage 27 Intake manifold 40 Exhaust passage 41 Exhaust manifold 42 Exhaust purification device 43 Exhaust temperature sensor 50 , 150 Fuel reformer 54 Reformed gas supply path 54a to 54d First to fourth reformed gas supply path 55 Reformed gas flow rate adjusting means 55a to 55d First to fourth reformed gas flow rate adjusting means 60 Electrons Control device

Claims (5)

In an internal combustion engine having a plurality of cylinders that can be operated using a reformed gas generated from a predetermined fuel in a fuel reformer as a fuel,
An internal combustion engine comprising control means for stopping an ignition operation for a part of the cylinders. The fuel reformer is configured so that the supply amount of the generated reformed gas can be adjusted for each cylinder,
2. The control device according to claim 1, wherein the control means is configured to control the fuel reformer so that a supply amount of reformed gas to the cylinder for stopping the ignition operation is larger than that of the other cylinders. The internal combustion engine described. In an internal combustion engine having a plurality of cylinders that can be operated using a reformed gas generated from a predetermined fuel in a fuel reformer as a fuel,
An internal combustion engine comprising a control means for controlling an air-fuel mixture of reformed gas and air to some cylinders of each of the cylinders to a rich side with respect to an air-fuel mixture of other cylinders. The fuel reformer is configured so that the supply amount of the generated reformed gas can be adjusted for each cylinder,
The said control means is comprised so that control of the said fuel reformer may be performed so that the supply amount of the reformed gas to the said cylinder to be over-concentrated may become larger than another cylinder. The internal combustion engine described.   5. The internal combustion engine according to claim 3, wherein the control unit is configured to control an air-fuel mixture in a cylinder other than the cylinder to be enriched to a lean side.

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