JP2019094906A - Control device of internal combustion engine, and internal combustion engine for land and marine industry using the same - Google Patents

Abstract

To provide a control device of an internal combustion engine capable of improving combustion for countermeasures against exhaust gas while using an inexpensive fuel.SOLUTION: A control device of an internal combustion engine includes a main fuel supply line 22 for supplying a main fuel to a plurality of cylinders 10, an auxiliary fuel supply line 24 for supplying an auxiliary fuel to at least one of the plurality of cylinders 10, fuel switch setting means 102a for setting switch of the main fuel and the auxiliary fuel, and a three-way valve 26 for switching the main fuel and the auxiliary fuel. The fuel switch setting means 102a estimates a combustion state of the plurality of cylinders 10 according to at least one of properties of an exhaust gas from the plurality of cylinders 10, cylinder internal pressures of the plurality of cylinders 10 or a load condition of the internal combustion engine, sets the switch of the main fuel and the auxiliary fuel supplied to the plurality of cylinders 10 on the basis of the estimated combustion state, and controls the supply of the main fuel and the auxiliary fuel to the cylinder 10 set by the fuel switch setting means 102 among the plurality of cylinders 10 by switching the three-way valve 26.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an internal combustion engine and an internal combustion engine for land and marine industries using the same.

  As a technology for reducing nitrogen oxides (NOx) contained in exhaust gas from internal combustion engines such as diesel engines, post-treatments such as selective catalytic reduction denitrification (SCR) are known. There is a problem that application is difficult because the temperature is low. On the other hand, an exhaust gas recirculation system (EGR) is also known which reduces nitrogen oxides (NOx) by circulating exhaust gas to the intake side.

  A configuration is disclosed in which a gas engine directly connected to a diesel engine is provided, and exhaust gas from a gas engine that is substantially free of hydrocarbons and dust is recycled to the diesel engine (Patent Document 1). In addition, a configuration has been disclosed in which exhaust of an Otto cycle engine for auxiliary equipment whose exhaust processing is relatively easy is led to the intake system of a diesel engine for a main engine to reduce nitrogen oxides (NOx) as a whole (Patented Literature 2). Further, there is disclosed a control device for an internal combustion engine in which an EGR passage connecting an exhaust passage and an intake passage is provided in some of a plurality of cylinders to circulate exhaust gas (Patent Document 3).

Unexamined-Japanese-Patent No. 5-71425 Japanese Patent Application Laid-Open No. 7-42623 Patent No. 4862623 gazette

  By the way, in order to apply EGR, it is necessary to use a high-quality, high-quality fuel having a low sulfur content to avoid engine corrosion. On the other hand, in a large internal combustion engine used for ships and the like, the proportion of fuel cost is particularly high, so it is desirable to use fuel which is as cheap as possible. In ships, there are a main engine, which is an internal combustion engine for driving a propeller, and an auxiliary engine, which is an internal combustion engine for producing electricity used in a ship, and in the auxiliary engine, good fuel is used with less generation of soot. In the main engine, it is conceivable to use cheap fuel and use exhaust gas with little soot emitted from the auxiliary engine as a gas for EGR of the main engine. However, since the amount of exhaust gas from the auxiliary engine is less than 10% of the amount of exhaust gas from the main engine, the EGR rate can not be increased. Therefore, the EGR rate of the main engine can be made 10% or more by using a good fuel for some of the cylinders of the main engine. It is also possible to improve combustion using good fuel only for cylinders with poor combustion.

  The present invention provides an internal combustion engine control device and an internal combustion engine for the land and marine industry, in which combustion is improved for exhaust gas countermeasures while using fuel that is as inexpensive as possible.

  A control device for an internal combustion engine according to a first aspect of the present invention is a control device for an internal combustion engine having a plurality of cylinders, and a main fuel system for supplying main fuel to the plurality of cylinders, and at least at least one of the plurality of cylinders. The fuel switching device comprises: a secondary fuel system for supplying secondary fuel to one, a fuel switching setting means for setting switching between the main fuel and the secondary fuel, and a fuel switching means for switching between the main fuel and the secondary fuel The setting means estimates and estimates the combustion state of the plurality of cylinders according to at least one of the properties of the exhaust gas from the plurality of cylinders, the in-cylinder pressure of the plurality of cylinders, or the load condition of the internal combustion engine Switching of the main fuel and the auxiliary fuel supplied to the plurality of cylinders is set based on the determined combustion state, and the main fuel to the cylinder set in the fuel switching setting means among the plurality of cylinders And before The control apparatus for an internal combustion engine, characterized in that the supply of secondary fuel is controlled by switching the fuel switching means.

  Further, fuel injection condition changing means for changing the injection conditions of the main fuel and the sub fuel supplied to the cylinder is provided, and supply of the main fuel and the sub fuel to the cylinder set in the fuel switching setting means is performed. Preferably, the fuel injection condition changing means makes the injection condition to the cylinder to which the main fuel is supplied different from the injection condition to the cylinder to which the sub fuel is supplied.

  For example, it is preferable that the fuel injection condition changing unit changes a fuel supply amount and / or a fuel injection timing as the injection condition.

  At this time, it is preferable that the fuel injection condition changing means automatically change the injection condition to the cylinder to which the sub fuel is supplied according to the property of the sub fuel.

  Further, an exhaust passage for discharging exhaust gas of the cylinder, an EGR passage for returning at least one exhaust gas of the cylinder to intake air, an EGR switching setting means for setting switching between the exhaust passage and the EGR passage, The EGR switching means is provided for switching between the exhaust passage and the EGR passage, and the EGR switching means sets the EGR switching for at least one of the cylinders switched to the auxiliary fuel by the setting of the fuel switching setting means. It is preferable to switch from the exhaust passage to the EGR passage according to the setting of the means.

  Here, preferably, the EGR passage is provided with an EGR valve capable of changing the passage area, and the flow rate of the exhaust gas passing through the EGR passage is adjusted using the EGR valve according to an EGR rate.

  Further, it is preferable to adjust the flow rate of the exhaust gas passing through the EGR passage by changing the number of cylinders switched to the auxiliary fuel according to the EGR rate.

  Further, the EGR switching setting means sets, as the cylinder to be supplied with the auxiliary fuel, one of the plurality of cylinders whose combustion timing is deviated equally when performing switching setting of the exhaust passage and the EGR passage. Is preferred.

  Further, when the switching from the exhaust passage to the EGR passage is set in the EGR switching setting unit, the EGR switching unit switches the EGR switching unit after the fuel switching unit switches from the main fuel system to the sub fuel system. It is preferable to switch from the exhaust passage to the EGR passage. Also, conversely, when switching from the EGR passage to the exhaust passage is set by the EGR switching setting unit, the fuel switching unit switches the EGR passage from the EGR passage to the exhaust passage. It is preferable to switch from the secondary fuel system to the main fuel system.

  Furthermore, it is preferable that the EGR passage from the cylinder to which the auxiliary fuel is supplied be provided with a NOx removal device for reducing nitrogen oxides in the exhaust gas.

  Further, it is preferable that the EGR passage from the cylinder to which the auxiliary fuel is supplied be provided with a supercharger. At this time, it is preferable that the supercharger is a supercharger with a generator.

  Preferably, the fuel switching setting means sets a cylinder for supplying the main fuel and a cylinder for supplying the auxiliary fuel in accordance with geographical conditions of the current position of the movable body.

  Preferably, the secondary fuel is a fuel having a sulfur content lower than that of the main fuel. For example, it is preferable that the main fuel be a C fuel oil or the like, and the auxiliary fuel be a fuel such as A fuel oil or light oil having a sulfur component smaller than that of the main fuel. In the case of a dual fuel engine, the main fuel may be heavy oil and the auxiliary fuel may be gas.

  Moreover, it is suitable to use the control apparatus of the said internal combustion engine for the internal combustion engine for land and marine industry.

  According to the control apparatus for an internal combustion engine according to a first aspect of the present invention, there is provided a control apparatus for an internal combustion engine having a plurality of cylinders, the main fuel system supplying main fuel to the plurality of cylinders, and the plurality of cylinders And a fuel switching means for switching between the main fuel and the auxiliary fuel, and a fuel switching means for switching between the main fuel and the auxiliary fuel. The fuel switching setting means estimates combustion states of the plurality of cylinders according to at least one of the property of exhaust gas from the plurality of cylinders, the in-cylinder pressure of the plurality of cylinders, or the load condition of the internal combustion engine. The switching of the main fuel and the auxiliary fuel supplied to the plurality of cylinders is set based on the estimated combustion state, and to the cylinder set in the fuel switching setting means among the plurality of cylinders. Primary fuel And by controlling the supply of the auxiliary fuel by switching the fuel switching means, the fuel combustion in each cylinder can be improved by using the auxiliary fuel as necessary to take measures against exhaust gas, and it is expensive. The fuel cost can be reduced by using together with the inexpensive main fuel without unnecessarily using the secondary fuel.

  Further, fuel injection condition changing means for changing the injection conditions of the main fuel and the sub fuel supplied to the cylinder is provided, and supply of the main fuel and the sub fuel to the cylinder set in the fuel switching setting means is performed. At the same time, the fuel injection condition changing means changes the injection condition to the cylinder to which the main fuel is supplied and the injection condition to the cylinder to which the sub fuel is supplied, so that the fuel of the main fuel and the sub fuel is changed. It is possible to reduce the variation in the combustibility and the output characteristic in each cylinder due to the difference in the characteristics (fuel density and calorific value).

  For example, the fuel injection condition changing means controls a parameter that particularly affects the combustion of the fuel by changing the fuel supply amount and / or the injection timing of the fuel as the injection condition to control the main fuel and the sub fuel. It is possible to reduce the variation in combustibility and output characteristics in each cylinder due to the difference in fuel characteristics.

  In particular, the fuel injection condition changing means automatically changes the injection condition to the cylinder to which the sub fuel is supplied according to the property of the sub fuel so that the combustibility and the output due to the difference in the fuel characteristics of the fuel can be obtained. Characteristic variations can be eliminated automatically.

  Further, an exhaust passage for discharging exhaust gas of the cylinder, an EGR passage for returning at least one exhaust gas of the cylinder to intake air, an EGR switching setting means for setting switching between the exhaust passage and the EGR passage, The EGR switching means is provided for switching between the exhaust passage and the EGR passage, and the EGR switching means sets the EGR switching for at least one of the cylinders switched to the auxiliary fuel by the setting of the fuel switching setting means. By switching from the exhaust passage to the EGR passage according to the setting of the means, an internal combustion engine using a sulfur component by utilizing only the exhaust gas from the cylinder using the auxiliary fuel which is a good fuel with a small sulfur component Reduce the generation of nitrogen oxides (NOx) in each cylinder and take measures against exhaust gas while suppressing the corrosion of It can be.

  Here, the EGR passage is provided with an EGR valve capable of changing the passage area, and by adjusting the flow rate of the exhaust gas passing through the EGR passage using the EGR valve according to the EGR rate, it is preferable that the sulfur component is reduced. Nitrogen oxide (NOx) in each cylinder while adjusting the amount of exhaust gas used for EGR among the exhaust gases from the cylinders using the secondary fuel which is the fuel to suppress the corrosion of the internal combustion engine due to the sulfur component The occurrence of can be appropriately reduced.

  Also, by changing the number of cylinders switched to the auxiliary fuel according to the EGR rate and adjusting the flow rate of the exhaust gas passing through the EGR passage, the cylinder using the auxiliary fuel which is a good fuel with a small amount of sulfur components The amount of exhaust gas used for EGR among the exhaust gas from the engine is adjusted to suppress the corrosion of the internal combustion engine due to the sulfur component, and without increasing the number of cylinders using unnecessarily expensive auxiliary fuel The generation of nitrogen oxides (NOx) in the cylinders can be appropriately reduced.

  Further, the EGR switching setting means sets, as the cylinder to be supplied with the auxiliary fuel, one of the plurality of cylinders whose combustion timing is deviated equally when performing switching setting of the exhaust passage and the EGR passage. Thus, it is possible to reduce the temporal fluctuation of the rotation due to the difference in combustion between the cylinder using the main fuel and the cylinder using the auxiliary fuel, and to drive the internal combustion engine smoothly. In addition, the exhaust gas from the cylinders using the auxiliary fuel used for EGR is equally supplied to the intake of each cylinder, and the unevenness of the ratio of the exhaust gas in the air supply is eliminated, and the internal combustion engine is driven smoothly. be able to.

  Further, when the switching from the exhaust passage to the EGR passage is set in the EGR switching setting unit, the EGR switching unit switches the EGR switching unit after the fuel switching unit switches from the main fuel system to the sub fuel system. By switching from the exhaust passage to the EGR passage, it is possible to introduce only the exhaust gas from the cylinder switched to the good secondary fuel having a low sulfur component into the EGR passage, and the EGR passage at the time of switching And the combustion chamber of the cylinder can be prevented from being polluted by the exhaust gas rich in sulfur components and soot.

  Also, conversely, when switching from the EGR passage to the exhaust passage is set by the EGR switching setting unit, the fuel switching unit switches the EGR passage from the EGR passage to the exhaust passage. By switching from the secondary fuel system to the main fuel system, only the cylinders switched from EGR to normal exhaust are switched from the high quality secondary fuel with little sulfur component to the main fuel, so It is possible to prevent the EGR passage and the combustion chamber of the cylinder from being polluted by the exhaust gas rich in the sulfur component and the soot.

  Further, the EGR passage from the cylinder to which the auxiliary fuel is supplied is provided with a denitration device for reducing nitrogen oxides in the exhaust gas, thereby suppressing the deterioration of the denitration device and also oxidizing nitrogen in the exhaust gas. NOx (NOx) can be further reduced.

  Further, by providing the supercharger in the EGR passage from the cylinder to which the auxiliary fuel is supplied, the energy of the exhaust gas from the cylinder using the auxiliary fuel can also be effectively used. Further, since the supercharger is a supercharger with a generator, energy of exhaust gas from a cylinder using the auxiliary fuel can be more effectively used, and the load on the generator can be adjusted to control EGR. The rate can be adjusted.

  In addition, the fuel switching setting means sets the cylinder supplying the main fuel and the cylinder supplying the sub fuel according to the geographical condition of the current position of the moving body, so that the exhaust gas differs depending on the geographical condition. The internal combustion engine can be driven under optimum operating conditions while improving the properties of the exhaust gas according to the regulations.

  Further, since the secondary fuel is a fuel having a sulfur content lower than that of the main fuel, it is possible to improve the utilization rate of EGR or the like and take measures against the exhaust gas while improving the properties of the exhaust gas.

  In addition, when the control device for the internal combustion engine is used in an internal combustion engine for land and marine industries, the combustion of fuel in each cylinder is improved to take measures against exhaust gas, and expensive auxiliary fuel is not unnecessarily used. An internal combustion engine for land and marine industries can be provided which can reduce the fuel cost by using it together with an inexpensive main fuel.

FIG. 1 is a diagram showing a configuration of an internal combustion engine in a first embodiment. It is a figure which shows the structure of the modification of the internal combustion engine in 1st Embodiment. It is a figure which shows the structure of the internal combustion engine in 2nd Embodiment. It is a figure which shows the structure of the modification of the internal combustion engine in 2nd Embodiment. It is a figure which shows the structure of the modification of the internal combustion engine in 2nd Embodiment. It is a figure which shows the structure of the internal combustion engine in 3rd Embodiment. It is a figure which shows the structure of the modification of the internal combustion engine in 3rd Embodiment.

First Embodiment
An internal combustion engine 100 according to an embodiment of the present invention includes a plurality of cylinders 10, as shown in FIG. Although internal combustion engine 100 is described as having six cylinders 10a to 10f, the number of cylinders 10 is not limited to this. Each cylinder 10 generates power by burning the fuel supplied thereto. In the present embodiment, the internal combustion engine 100 will be described by way of an example of a so-called in-cylinder direct injection type diesel internal combustion engine in which fuel is directly injected to each cylinder 10.

  In the first embodiment, since each of the cylinders 10 (10a to 10f) has the same configuration, the following description will be made with the cylinder 10a as a representative.

  The cylinder 10a is provided with a cylinder block, a cylinder head, a piston and a crankshaft (not shown). A cylinder bore is formed in the cylinder block, and the piston is arranged to be able to reciprocate in the cylinder bore. Further, a cylinder head is coupled to the cylinder block so as to surround the cylinder bore opposite to the piston. A space surrounded by the cylinder bore, the cylinder head and the head of the piston is a combustion chamber.

  The cylinder 10 a is provided with an intake (air supply) port 12 and an exhaust port 14. An intake valve 16 is provided at the intake port 12. The exhaust port 14 is provided with an exhaust valve 18. The cylinder 10a is provided with a crank angle sensor (not shown) that detects the rotational angle position of the crankshaft according to the movement of the piston, and a signal related to the detected rotational angle position is input to the control device 102. The control device 102 opens and closes the intake valve 16 according to the movement (crank angle) of the piston, and the timing of intake (air supply) to the cylinder 10a is controlled. Further, the control device 102 opens and closes the exhaust valve 18 according to the movement (crank angle) of the piston, and the exhaust from the cylinder 10a is controlled.

  The cylinder 10a is provided with a fuel injection device 20 for supplying fuel. The fuel injection device 20 is connected to a main fuel supply line 22 for supplying a main fuel and an auxiliary fuel supply line 24 for supplying an auxiliary fuel. The main fuel supply line 22 and the auxiliary fuel supply line 24 are connected to the fuel injection device 20 via a three-way valve 26 which is a fuel switching means. A main fuel tank 22a and a main fuel pump 22b are provided in the main fuel supply line 22, and the main fuel stored in the main fuel tank 22a is pressurized by the main fuel pump 22b and supplied to the main fuel supply line 22. . The auxiliary fuel supply line 24 is provided with an auxiliary fuel tank 24a and an auxiliary fuel pump 24b, and the auxiliary fuel stored in the auxiliary fuel tank 24a is pressurized by the auxiliary fuel pump 24b and supplied to the auxiliary fuel supply line 24. Be done. The fuel injection device 20 directly injects the supplied main fuel or auxiliary fuel into the cylinder 10a. The fuel injection device 20 may be capable of performing multiple fuel injections during one cycle of the internal combustion engine 100.

  Here, the secondary fuel is a fuel of better quality than the main fuel. For example, it is preferable that the main fuel be C heavy oil or the like, and the auxiliary fuel be a fuel such as A heavy oil or light oil having a sulfur component smaller than that of the main fuel. In the case of a dual fuel engine, the main fuel may be heavy oil and the auxiliary fuel may be gas.

  Air is taken into the cylinder 10a from the intake port 12 according to the vertical movement of the piston. Furthermore, fuel (main fuel or secondary fuel) is supplied by the fuel injection device 20, and a mixture of air and fuel is formed in the cylinder 10a.

  In the case of a direct injection diesel internal combustion engine, combustion is performed by compression ignition. In addition, an ignition plug may be provided in the cylinder 10a as an ignition device for igniting the air-fuel mixture. It is also possible to generate a spark by applying a voltage to the electrode of the spark plug to ignite and burn the mixture supplied into the cylinder 10a. The combustion generates a driving force that causes the piston to reciprocate, and the reciprocation is converted to rotational motion and output from the crankshaft.

  The exhaust port 14 is provided with an exhaust passage 30 for exhausting the exhaust gas discharged from the cylinder 10a. A turbocharger 32 is connected to the exhaust passage 30. The turbocharger 32 compresses intake air by the energy of the exhaust gas. The turbocharger 32 rotationally drives the turbine wheel and the compressor wheel by the energy of the inflowing exhaust gas, compresses the air by the compressor, and feeds it to the intake port 12 via the intercooler 34.

  Further, an exhaust gas recirculation (EGR) passage 36 is connected to the exhaust port 14 in parallel with the exhaust passage 30. The exhaust passage 30 and the exhaust gas recirculation passage 36 are connected to the exhaust port 14 via an EGR three-way valve 38 which is an EGR switching means. The control device 102 functions as the EGR switching setting means 102c, and distributes the exhaust gas discharged from the cylinder 10a exclusively to general exhaust gas and EGR by switching the EGR three-way valve 38.

  The EGR system includes a blower 40, an EGR cooler 42 and an EGR valve 44 provided in the exhaust gas recirculation passage 36. The exhaust gas introduced into the exhaust gas recirculation passage 36 is boosted by the blower 40 and sent to the EGR cooler 42. The EGR cooler 42 reduces the exhaust gas to the temperature of the supply gas and supplies it to the intake port 12. The EGR cooler 42 has a cooler body and a condensed water collection unit. That is, the exhaust gas is pressurized and transported by the blower 40, and the temperature is further reduced by the EGR cooler 42 and supplied to the intake port 12. The EGR valve 44 is used to adjust the flow rate of the exhaust gas flowing through the exhaust gas recirculation passage 36.

  When the EGR system is activated, part of the exhaust gas discharged from the cylinder 10 a is recirculated to the intake port 12. As a result, exhaust gas containing carbon dioxide and low in oxygen is mixed with air containing sufficient oxygen and supplied into the cylinder 10a. Therefore, the gas filling efficiency in the cylinder 10a can be enhanced to reduce the pump loss, and the combustion temperature in the cylinder 10a can be lowered to suppress the generation of nitrogen oxides and the like.

  Note that part of the exhaust gas introduced into the exhaust gas recirculation passage 36 via the turbocharger 32 may be discharged to the outside. Since the flow rate of the exhaust gas recirculated by the EGR valve 44 is adjusted, the remaining exhaust gas not utilized for recirculation can be exhausted through the turbocharger 32.

  The other cylinders 10b to 10f also have the same configuration as that of the cylinder 10a. The timing of intake to each cylinder 10 (10a to 10f), the timing of fuel injection, and the timing of ignition are configured to be controllable independently of each other by the control device 102. Specifically, it is preferable that the timing of ignition in each cylinder 10 be controlled so as to be uniform in time. For example, in the six-cylinder two-stroke internal combustion engine 100 having the cylinders 10a to 10f, it is preferable to set the timing of ignition every 60 degrees of crank angle.

  The control device 102 functions as the fuel switching setting means 102a, and by switching the three-way valve 26 which is the fuel switching means, one of the main fuel and the auxiliary fuel is exclusively supplied to each of the cylinders 10 (10a to 10f). Control. Here, the fuel switching setting means 102 a switches the fuel supplied to each cylinder 10 according to the operating state of the internal combustion engine 100. Specifically, it is preferable to set the state of the three-way valve 26 so that the fuel switching setting means 102a supplies the secondary fuel only to the cylinder 10 with bad combustion and supplies the main fuel to the remaining cylinders 10 is there.

  For example, the fuel switching setting means 102a provides an exhaust gas sensor (not shown) at the exhaust port 14 of each cylinder 10, and sets the fuel supplied to each cylinder 10 according to the property of the exhaust gas. In this case, the fuel switching setting means 102a determines the concentration of nitrogen oxides (NOx), carbon monoxide (CO), smoke (amount of particulate matter in the exhaust gas) and total hydrocarbons (THC) in the exhaust gas. Depending on at least one, the three-way valve 26 is switched to control each cylinder 10 to be supplied with the main fuel or the auxiliary fuel. That is, the fuel switching setting means 102a determines the combustion in each cylinder 10 from at least one of the measured values of nitrogen oxides (NOx), carbon monoxide (CO), smoke and total hydrocarbons (THC) in the exhaust gas. The three-way valve 26 is switched according to the estimated combustion state or measured values of nitrogen oxide (NOx), carbon monoxide (CO), smoke and total hydrocarbon (THC) itself and the respective cylinders 10. Switch the primary fuel or secondary fuel supplied to the

  Further, the fuel switching setting means 102a may be provided with a pressure sensor (not shown) for each cylinder 10, and may set the fuel supplied to each cylinder 10 according to the pressure in the cylinder. The pressure sensor can be configured to measure the force applied to the cylinder head by a sensor that measures the force acting on the cylinder head bolt, a strain sensor, or the like. Alternatively, the pressure in the cylinder 10 may be directly detected. In these cases, it can be determined that the combustion in the cylinder 10 is better as the in-cylinder pressure is higher. The fuel switching setting means 102 a switches the three-way valve 26 in accordance with the in-cylinder pressure of each cylinder 10 to switch the main fuel or the auxiliary fuel supplied to each cylinder 10.

Further, the fuel switching setting means 102a may set the fuel supplied to each cylinder 10 in accordance with the load condition of the engine, the geographical condition and the like. The load condition of the engine is determined by the operation conditions of a ship or the like on which the internal combustion engine 100 is set in advance. For example, it is possible to set an exhaust gas regulation value (NOx regulation, CO regulation, smoke regulation, SOx regulation, CO ₂ emission regulation) or the like which varies depending on geographical conditions as the operation condition. Furthermore, the operation mode may be selected to set the environment-oriented setting (environmental mode) or the fuel efficiency-oriented setting (eco mode). The operating conditions are calculated according to these conditions, and the exhaust temperature target value, the target value of efficiency, the load condition, etc. are calculated, so the fuel switching setting means 102a switches the three-way valve 26 according to the calculation result The main fuel or auxiliary fuel supplied to the cylinder 10 is switched.

  Moreover, GPS (not shown) and a radar may be mounted and operation conditions may be calculated from the present position. By GPS or radar, the distance from land, the direction and distance from the destination, and the positional relationship with the target at the time of navigation can be acquired, and the operating conditions can be calculated according to these. For example, if the current position is in a port or a position near the land, the operation mode (environment mode) giving priority to exhaust gas purification is selected, and if it is the open sea, the operation mode giving priority to fuel efficiency (eco mode). Then, the fuel switching setting means 102a switches the three-way valve 26 according to the operation mode to switch the main fuel or the auxiliary fuel supplied to each cylinder 10.

  Further, the control device 102 functions as the fuel injection condition changing means 102 b and controls the injection timing and the injection amount of the fuel in the fuel injection device 20 independently to each of the cylinders 10. That is, the fuel density and the amount of heat generation differ depending on whether the fuel supplied to each cylinder 10 is the main fuel or the auxiliary fuel, and the state of combustion in the cylinders changes, so the fuel supplied to each cylinder 10 Adjust the fuel injection timing and injection amount according to the type of

  Specifically, the injection conditions (injection period (injection period)), injection pressure, and crank angle with respect to which injection pressure (injection period) is the target value at which the maximum in-cylinder pressure, heat generation amount, exhaust temperature, ignition timing etc. in each cylinder 10 are preset. The injection timing (injection timing) is registered for each type of fuel, and the fuel injection condition changing means 102b is an injection in which the fuel supplied to each cylinder 10 is registered according to the type of the main fuel or the auxiliary fuel The condition may be read out and controlled to be the injection condition. For example, the fuel injection is performed so that at least one of the maximum in-cylinder pressure, the heat generation amount, the exhaust gas temperature, and the ignition timing of the cylinder 10 to which the main fuel is supplied and the cylinder 10 to which the auxiliary fuel is supplied becomes equivalent. Change the conditions.

  As described above, by switching the fuel for each cylinder 10 to enable operation, the state of combustion in each cylinder 10 can be improved.

  Preferably, the cylinders 10 for introducing the auxiliary fuel are selected such that the timing of combustion, that is, the timing of combustion, is uniformly shifted. For example, when the auxiliary fuel is introduced to the two cylinders in four strokes, the cylinder 10 whose ignition timing is shifted by 360 ° is selected. Further, in the case where the auxiliary fuel is introduced to the two cylinders in two strokes, the cylinder 10 whose ignition timing is shifted by 180 ° is selected.

  Thereby, it is possible to reduce the temporal fluctuation of the rotation due to the difference in combustion between the cylinder 10 using the main fuel and the cylinder 10 using the sub fuel, and to drive the internal combustion engine 100 smoothly. Can. In addition, the exhaust gas from the cylinders using the auxiliary fuel used for EGR is equally supplied to the intake of each cylinder, and the unevenness of the ratio of the exhaust gas in the air supply is eliminated, and the internal combustion engine is driven smoothly. be able to.

  Further, the EGR switching setting means 102c sets the cylinder 10 for introducing the exhaust gas into the exhaust gas recirculation passage 36 among the cylinders 10 to which the auxiliary fuel is supplied, and switches the EGR three-way valve 38 of the cylinder 10 for exhaust gas. Flow to the exhaust gas recirculation passage 36. The cylinders 10 using EGR may be all or part of the cylinders 10 to which the auxiliary fuel is supplied.

  Specifically, the EGR switching setting means 102c may set the number of cylinders 10 using EGR in accordance with the EGR rate set in advance. For example, in the case of a six-cylinder internal combustion engine 100, if the EGR rate is 30%, two cylinders out of the cylinders 10 to which auxiliary fuel is supplied are set as the cylinders 10 for EGR, and the EGR rate is 15%. If it exists, one of the cylinders 10 to which the auxiliary fuel is supplied is set as the cylinder 10 using EGR.

  Further, the control device 102 may control the flow rate of the exhaust gas at the EGR valve 44 in accordance with the EGR rate. For example, the timing, period, and opening ratio of opening the EGR valve 44 may be adjusted according to the EGR rate.

  As described above, by utilizing only the exhaust gas from the cylinders 10 using the auxiliary fuel, which is a good fuel having a small amount of sulfur components, for EGR, the corrosion of the internal combustion engine 100 due to the sulfur components is suppressed. Combustion can be improved and nitrogen oxides (NOx) can be reduced. On the other hand, it is economically advantageous to use a low priced main fuel for the cylinder 10 which does not require improvement in combustion. In the dual fuel engine, the exhaust gas from the cylinder 10, which uses the auxiliary fuel gas, is applied to the exhaust gas for EGR, and methane is burned by recirculating to the cylinder 10 to reduce the methane slip. Can.

  Further, it is preferable to introduce the auxiliary fuel only to the cylinder 10 used for EGR. In this case, all exhaust gases of the cylinder 10 to which the auxiliary fuel is supplied are applied as exhaust gases for EGR. When the EGR rate is low, the number of cylinders 10 using high quality and expensive secondary fuel can be reduced, and economical operation can be performed by increasing the proportion of low-cost main fuel.

  The EGR switching setting means 102c supplies the auxiliary fuel to the cylinder 10 among the cylinders 10 whose ignition timing (combustion timing) deviates uniformly when switching setting of the exhaust gas recirculation passage 36 from the exhaust passage 30. It is preferable to set as. Thereby, it is possible to reduce the temporal fluctuation of the rotation due to the difference in combustion between the cylinder 10 using the main fuel and the cylinder 10 using the sub fuel, and to drive the internal combustion engine 100 smoothly. Can. In addition, the exhaust gas from the cylinders using the auxiliary fuel used for EGR is equally supplied to the intake of each cylinder, and the unevenness of the ratio of the exhaust gas in the air supply is eliminated, and the internal combustion engine is driven smoothly. be able to.

  Further, when switching from the exhaust passage 30 to the exhaust gas recirculation passage 36 is set in the EGR switching setting means 102c, the three-way valve 26 of the corresponding cylinder 10 is switched from the main fuel system to the secondary fuel system by the fuel switching setting means 102a. It is preferable to switch the EGR three-way valve 38 of the cylinder 10 from the exhaust passage 30 to the exhaust gas recirculation passage 36 after it has been received.

  As a result, only the exhaust gas from the cylinder 10 switched to the good quality secondary fuel having a low sulfur content can be introduced into the exhaust gas recirculation passage 36, and the exhaust gas recirculation passage 36, the EGR cooler 42, It is possible to prevent the 10 combustion chambers from being polluted by the exhaust gas rich in sulfur components and soot.

  Also, when switching from the exhaust gas recirculation passage 36 to the exhaust gas passage 30 is set in the EGR switching setting means 102c, after switching the EGR three-way valve 38 from the exhaust gas recirculation passage 36 to the exhaust gas passage 30, the three-way valve 26 It is preferable to switch from the secondary fuel system to the main fuel system.

  As a result, after switching from EGR to normal exhaust, it is possible to switch from good secondary fuel with little sulfur component to main fuel, so the exhaust recirculation passage 36, EGR cooler 42 and combustion chamber of the cylinder 10 at the time of switching It can be prevented from being polluted by exhaust gas with many components and soot.

  In the present embodiment, the fuel switching means and the EGR switching means are provided to all the cylinders 10 (10a to 10f), but the present invention is not limited to this. As shown in FIG. 2, the internal combustion engine 200 may be provided with fuel switching means and EGR switching means only in some of the cylinders 10. The internal combustion engine 200 shows an example in which a fuel switching unit and an EGR switching unit are provided only in the cylinder 10c and the cylinder 10d.

  In this case, in the range of the cylinder 10 (10c, 10d) provided with the fuel switching means and the EGR switching means, switching of the main fuel and the secondary fuel and switching of general exhaust and EGR may be performed according to the combustion state or the like. it can.

Second Embodiment
As shown in FIG. 3, the internal combustion engine 300 may be provided with a selective catalyst reduction denitration device (SCR) 50 in the exhaust gas recirculation passage 36. The SCR is an apparatus that converts nitrogen oxides (NOx) into molecular nitrogen (N ₂ ) and water (H ₂ O) by adding a reducing agent such as ammonia or urea to exhaust gas and introducing it into the catalyst. .

  The selective catalytic reduction denitration device 50 may be disposed in front of the blower 40 on the exhaust gas recirculation passage 36 as shown in FIG. 3 or the exhaust gas recirculation passage of each cylinder 10 as shown in FIG. You may arrange on 36. Further, as shown in FIG. 5, the selective catalyst reduction denitration device 50 may be provided so as to treat the exhaust gas exhausted to the outside without passing through the blower 40, the EGR cooler 42 and the EGR valve 44.

  As described above, by introducing only the exhaust gas from the cylinder 10 using the auxiliary fuel into the selective catalytic reduction denitration device 50, the deterioration of the catalyst of the SCR is suppressed, and the nitrogen oxides in the exhaust gas are reduced. (NOx) can be reduced.

Third Embodiment
In the above embodiment, a part of the exhaust gas introduced into the exhaust gas recirculation passage 36 is introduced into the common turbocharger 32 and the common turbocharger 32, but without being introduced into the turbocharger 32. It may be released to the atmosphere. Further, as shown in FIG. 6, the internal combustion engine 400 may be provided with a dedicated EGR turbocharger 52 in the exhaust gas recirculation passage 36.

  Thereby, all the energy of the exhaust gas recirculated to the intake side can be utilized. In addition, since the exhaust gas to be recirculated is pressurized and sent to the intake port 12, the blower 40 can be miniaturized or eliminated.

  Preferably, a cooler 54 is provided in front of the compressor wheel of the EGR turbocharger 52. Since the exhaust gas to be recirculated is at a relatively high temperature, lowering the temperature in advance by the cooler 54 can prevent the exhaust gas from having a higher temperature by the pressurization by the EGR turbocharger 52.

  Note that, as shown in FIG. 7, a generator 56 may be provided to the EGR turbocharger 52. The energy of the exhaust gas introduced into the exhaust gas recirculation passage 36 by the generator 56 can be recovered. In addition, by adjusting the load of the generator 56, it is also possible to adjust the EGR rate.

  The application range of the control device for an internal combustion engine according to the present invention is not limited to a diesel engine, and may be an internal combustion engine provided with a plurality of cylinders of an internal ignition type and an external ignition type.

Reference Signs List 10 (10a-10f) cylinder, 20 fuel injection device, 22 main fuel supply line, 22a main fuel tank, 22b main fuel pump, 24 auxiliary fuel supply line, 24a auxiliary fuel tank, 24b auxiliary fuel pump, 26 three-way valve, 30 Exhaust passage, 32 turbochargers, 36 exhaust recirculation passages, 38 EGR three-way valves, 40 blowers, 42 EGR coolers, 44 EGR valves, 50 selective catalytic reduction denitration equipment, 52 EGR turbochargers, 54 coolers, 56 power generation 100, 200, 300, 400 Internal combustion engine 102 Control unit 102a Fuel switching setting means 102b Fuel injection condition changing means 102c EGR switching setting means.

Claims (16)

A control device for an internal combustion engine having a plurality of cylinders, comprising:
A main fuel system that supplies a main fuel to the plurality of cylinders, and a sub fuel system that supplies a sub fuel to at least one of the plurality of cylinders;
Fuel switching setting means for setting switching between the main fuel and the auxiliary fuel;
A fuel switching unit that switches between the main fuel and the auxiliary fuel;
The fuel switching setting means estimates the combustion state of the plurality of cylinders according to at least one of the property of exhaust gas from the plurality of cylinders, the in-cylinder pressure of the plurality of cylinders, or the load condition of the internal combustion engine Setting switching of the main fuel and the auxiliary fuel supplied to the plurality of cylinders based on the estimated combustion state;
A control device for an internal combustion engine, which controls supply of the main fuel and the auxiliary fuel to a cylinder set in the fuel switching setting means among the plurality of cylinders by switching the fuel switching means. The control device for an internal combustion engine according to claim 1,
Fuel injection condition changing means for changing the injection conditions of the main fuel and the auxiliary fuel supplied to the cylinder;
While switching the supply of the main fuel and the auxiliary fuel to the cylinder set in the fuel switching setting means, the fuel injection condition changing means is an injection condition for the cylinder to which the main fuel is supplied and the auxiliary fuel A control device for an internal combustion engine, which is different from an injection condition to a supplied cylinder. The control device for an internal combustion engine according to claim 2,
The control device of an internal combustion engine, wherein the fuel injection condition changing means changes a fuel supply amount and / or a fuel injection timing as the injection condition. A control device for an internal combustion engine according to claim 2 or 3, wherein
The control device for an internal combustion engine, wherein the fuel injection condition changing means automatically changes the injection condition to the cylinder to which the sub fuel is supplied according to the property of the sub fuel. The control device for an internal combustion engine according to any one of claims 1 to 4, wherein
An exhaust passage for discharging the exhaust gas of the cylinder;
An EGR passage for returning at least one exhaust gas of the cylinder to intake air;
EGR switching setting means for setting switching between the exhaust passage and the EGR passage;
And EGR switching means for switching between the exhaust passage and the EGR passage.
The EGR switching means switches from the exhaust passage to the EGR passage according to the setting of the EGR switching setting means for at least one of the cylinders switched to the auxiliary fuel by the setting of the fuel switching setting means. A control device for an internal combustion engine characterized by The control device for an internal combustion engine according to claim 5,
The EGR passage is provided with an EGR valve capable of changing the passage area,
A control system of an internal combustion engine, wherein a flow rate of the exhaust gas passing through the EGR passage is adjusted using the EGR valve according to an EGR rate. A control device for an internal combustion engine according to claim 5 or 6, wherein
A control device for an internal combustion engine, wherein the flow rate of the exhaust gas passing through the EGR passage is adjusted by changing the number of cylinders switched to the auxiliary fuel according to an EGR rate. The control device for an internal combustion engine according to any one of claims 5 to 7, wherein
When the EGR switching setting means performs switching setting of the exhaust passage and the EGR passage, a cylinder of which combustion timing is evenly deviated among the plurality of cylinders is a cylinder which is a switching object of the exhaust passage and the EGR passage. A control device of an internal combustion engine set as: A control device for an internal combustion engine according to any one of claims 5 to 8, wherein
When switching from the exhaust passage to the EGR passage is set in the EGR switching setting unit, the EGR switching unit is switched to the exhaust passage after the fuel switching unit switches from the main fuel system to the secondary fuel system. A control device for an internal combustion engine, wherein switching from the EGR passage to the EGR passage is performed. The control device for an internal combustion engine according to any one of claims 5 to 9, wherein
When switching from the EGR passage to the exhaust passage is set by the EGR switching setting unit, the fuel switching unit is switched from the auxiliary fuel system after the EGR switching unit switches from the EGR passage to the exhaust passage. A control device for an internal combustion engine, which performs switching to the main fuel system. A control device for an internal combustion engine according to any one of claims 5 to 10, wherein
A control device for an internal combustion engine, comprising a denitration device for reducing nitrogen oxides in the exhaust gas in the EGR passage from a cylinder to which the auxiliary fuel is supplied. A control device for an internal combustion engine according to any one of claims 5 to 11, wherein
A control device for an internal combustion engine, comprising a supercharger in the EGR passage from a cylinder to which the auxiliary fuel is supplied. A control device for an internal combustion engine according to claim 12.
The control device for an internal combustion engine, wherein the supercharger is a supercharger with a generator. The control device for an internal combustion engine according to any one of claims 1 to 13, wherein
The internal combustion engine is mounted on a moving body,
The control device for an internal combustion engine, wherein the fuel switching setting means sets a cylinder supplying the main fuel and a cylinder supplying the auxiliary fuel according to geographical conditions of the current position of the moving body. A control device for an internal combustion engine according to any one of claims 1 to 14, wherein
The control device for an internal combustion engine, wherein the secondary fuel is a fuel having a sulfur content lower than that of the main fuel.   An internal combustion engine for a land and marine industry equipped with the control device for an internal combustion engine according to any one of claims 1 to 15.