JP2018150937A - Method for increasing temperature in at least part of internal combustion engine system, and vehicle with the system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine system and a control method for an internal combustion engine system, which rapidly increase temperature in an exhaust gas aftertreatment system to a working temperature and/or maintain the increased temperature in a working temperature range for a long time period.SOLUTION: A method is for increasing temperature in an internal combustion engine system 100 in a critical temperature operation state such as a low temperature start state and comprises a step of determining whether the internal combustion engine system 100 operates in a critical temperature state, and a step of, when the internal combustion engine system 100 operates in the critical temperature state, exerting control to make a first cylinder group 2a inoperative by not feeding fuel to a cylinder of the first cylinder group 2a and exerting control to make a second cylinder group 2b operative by feeding fuel to a cylinder of the second cylinder group 2b, thereby increasing temperature in the internal combustion engine system 100.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for increasing the temperature in an internal combustion engine system and to a vehicle comprising such a system.

  In the case of current and future exhaust gas levels in vehicle internal combustion engines, particularly heavy duty diesel engines, exhaust gas aftertreatment is important for overall exhaust gas and fuel consumption. Vehicle drivability and reliability are also affected by the various methods used to meet these emissions standards.

  One known method uses a so-called exhaust gas aftertreatment system, usually in the form of a catalyst or particle filter. These catalyst aftertreatment systems operate in a suitable temperature range, for example 250 ° C. to 450 ° C., and this temperature range is easily maintained during normal driving conditions of the vehicle.

  However, when the engine is cold started or during an engine operation mode, the actual temperature is too low to be maintained in the temperature range.

  Thus, one of the most difficult challenges for operating an internal combustion engine system having an exhaust gas aftertreatment system 22 is to raise the temperature in the exhaust gas aftertreatment system to the operating temperature in a critical temperature operating state so as to meet the emission requirements. And maintain the elevated temperature.

  In addition to the cold start condition, there are some other critical temperature engine operating conditions of the internal combustion engine where the actual exhaust gas temperature is too low to be maintained in the temperature range when the vehicle is started after the engine is stopped. These critical temperature operating states are hereinafter referred to as “low load engine operating mode, idle engine operating mode, or motoring engine operating mode” and are described in further detail in the following paragraphs.

  “Idle engine operating state” represents all engine operating modes when the engine is operating at idle speed. The idle speed is a rotational speed when the engine is operated when the engine is separated from the power transmission system and the accelerator of the internal combustion engine is released. Usually, the rotational speed is measured in revolutions per minute of the engine crankshaft, that is, in rpm. At idle speed, the engine runs reasonably smoothly and has enough power to operate the engine accessories (water pump, alternator, and other accessories such as power steering, if equipped), It generates power that is not usually sufficient to perform heavy tasks such as moving the vehicle. In the case of vehicles such as trucks and passenger cars, the idle speed is usually 600 rpm or more and 1,000 rpm or less. Even when the accelerator is released, a certain amount of fuel is injected into the internal combustion engine to continue engine operation.

  If the engine operates a large number of accessories, especially air conditioning, the idle speed must be increased to ensure that the engine runs smoothly and generates enough power to operate the accessories. . Therefore, most engines are provided with an automatic adjustment function in the carburetor or the fuel injection system that increases the idle speed when more power is required.

  “Low load engine operating mode or motoring engine operating mode” is defined as the engine operating mode when the engine is operating at a speed above a certain rotational speed (rpm) but no fuel is injected into the engine. . As an example of the motoring engine operation mode, there is a motoring engine operation mode when the rotational speed of the engine is decreasing, that is, when the vehicle driven by the engine normally travels on a slope. During that mode, the accelerator is released, but the engine operation continues with the driving force of the transmission main shaft while the engine is coupled to the power transmission path.

  During the engine operating mode as described above, the engine in principle feeds fresh air at ambient temperature into the exhaust system, which causes the exhaust gas aftertreatment system to be “air cooled” in an uncontrolled (unfavorable form). Problems arise.

  This means that the exhaust gas aftertreatment can no longer be carried out effectively because the temperature in the catalyst exhaust gas aftertreatment system rapidly drops below 250 ° C.

  Therefore, a reduction in internal combustion engine efficiency is often caused as a result of increased exhaust gas regulation requirements. It is therefore important to provide a method that allows efficient exhaust gas regulation without adversely affecting engine efficiency and overall vehicle fuel consumption.

  Another approach to providing the required low emissions for an efficient internal combustion engine is to use so-called “partial premixed combustion (PPC)”. In short, PPC can be described as operating a compression ignition (diesel) engine with a low cetane number fuel, such as naphtha or kerosene. Low cetane number fuel works effectively at medium or high loads, but its flammability does not reach an acceptable range in low load and / or motoring engine operating modes. Thus, PPC can also be considered to induce critical temperature operating conditions, especially during cold start, idle operating conditions, and low load operating conditions, where the hydrocarbon compounds (HC) and carbon monoxide from the engine There arises a problem that (CO) is excessively discharged.

  As mentioned above, HC and CO emissions are not a problem as long as the exhaust gas aftertreatment system is in operation. However, if the catalyst temperature is below 250 ° C., the conversion efficiency decreases to an unacceptable level. As a result, the temperature of the exhaust gas aftertreatment system is maintained at a temperature higher than 250 ° C. and / or the temperature of the exhaust gas aftertreatment system is rapidly increased even at low loads or during idle engine operation mode or motoring engine operation mode. I have to let it.

  Accordingly, it is an object of the present invention to provide an internal combustion engine system and an internal combustion engine that rapidly increases the temperature in the exhaust gas aftertreatment system to the operating temperature and / or maintains the increased temperature within the operating temperature range for a long period of time. It is to provide a method for controlling an engine system.

  The above problem is solved by the internal combustion engine system according to claim 1, the internal combustion engine system control method according to claims 18, 22 and 28, and the vehicle according to claim 32.

  According to a first aspect of the invention, an object is to provide an internal combustion engine comprising a plurality of cylinders, a cylinder block having a gas intake manifold for supplying at least air to the cylinder block, and an exhaust gas manifold for discharging exhaust gas from the cylinder block. Solved by the system. The exhaust gas manifold has at least a main exhaust gas outlet and a waste gate exhaust gas outlet, the main exhaust gas outlet is connected to a main exhaust gas pipe for guiding the exhaust gas to the main exhaust gas aftertreatment system, and the waste gate exhaust gas outlet is a waste gate exhaust gas pipe Connected to. As a feature of the invention, a wastegate exhaust pipe is reconnected to the main exhaust pipe upstream of the main exhaust gas aftertreatment system and at least one wastegate posttreatment for performing catalyst treatment on the exhaust gas flowing in the wastegate exhaust pipe Part, preferably an oxidation catalyst such as a diesel oxidation catalyst. The main exhaust gas aftertreatment system may include at least one of an oxidation catalyst, a particulate filter, and a selective catalytic reactor.

Wastegate exhaust gas aftertreatment, especially diesel oxidation catalyst (DOC) and other suitable exhaust gas aftertreatment, uses O ₂ (oxygen) in the exhaust gas stream to convert CO (carbon monoxide) to CO ₂ (carbon dioxide). ) To convert HC (hydrocarbon) into H ₂ O (water) and CO ₂ . Since this conversion process is an exothermic process, sufficient heat is generated to raise the temperature of the entire exhaust gas, and as a result, the main exhaust gas aftertreatment system and the wastegate exhaust pipe arranged below the recombining part of the main exhaust pipe. Is maintained at or brought to its operating temperature, preferably 250 ° C. The temperature may be controlled by the amount of exhaust gas flowing through the wastegate exhaust pipe, and the amount of exhaust gas may be controlled by the diameter of the wastegate exhaust outlet valve and / or the wastegate exhaust pipe.

  The wastegate exhaust gas aftertreatment is further adapted to produce exhaust gas with sufficient heat to initiate an exothermic catalytic reaction with the main oxidation catalyst. In order to initiate an exothermic catalytic reaction with a wastegate oxidation catalyst and / or a main oxidation catalyst, an incombustible fuel that provides a certain amount of hydrocarbon source is required.

  According to still another preferred embodiment, the waste gate oxidation catalyst and the main oxidation catalyst may be configured to be the same part. Preferably, the integrated oxidation catalyst is connected to the waste gate exhaust pipe. 1 inlet and a second inlet connected to the main exhaust pipe. Thereby, the first inlet is preferably arranged upstream of the second inlet.

  According to yet another preferred embodiment, the non-combustible fuel may be provided by a fuel injector located in the wastegate exhaust pipe or in the wastegate exhaust pipe.

  In addition to or in lieu of the above, non-combustible fuel may be provided by so-called post-injection afterwards, in which the fuel is at the end of the combustion stroke so that the fuel does not ignite at least one of the cylinder blocks. It is injected into the cylinder. The strategy of injecting at a fairly late timing is known to cause oil dilution problems and must be used with caution. However, it takes less time to use this method to start the wastegate post-processing section and there is no oil dilution problem. Although details will be described later, this problem does not occur during the PPC combustion due to the high volatility of the PPC fuel. In PPC, there is no need to place a limit on using post-injection at a considerably later timing because of oil dilution.

  The later post-injection has the following further advantages. By performing the later post-injection at the right time, the fuel is pre-treated in the cylinder, and the hydrocarbons of the injected fuel are thereby converted to lighter hydrocarbons, CO and H2 (hydrogen). In the oxidation catalyst, light hydrocarbons are easier to ignite than hydrocarbons in the injected fuel. Furthermore, when the internal combustion engine is controlled to provide sufficient CO in the wastegate post-processing unit, the wastegate post-processing unit may ignite when the temperature reaches about 150 ° C. In order to produce maximum CO, the air / fuel ratio lambda may be controlled to provide a corresponding state, preferably a slightly richer state, in the wastegate exhaust pipe.

  Lambda (λ) is the ratio of the actual air / fuel ratio to the stoichiometric air / fuel ratio for a given mixture. Therefore, the general fuel composition changes from season to season, and many modern vehicles handle a variety of fuels, so lambda is not affected by variations in the fuel mixture. The stoichiometric mixture only contains enough air to completely burn the available fuel. Lambda 1.0 represents a stoichiometric mixture, a rich mixture is less than 1.0 and a lean mixture is greater than 1.0.

  As soon as the wastegate oxidation catalyst is ignited, the post-injection can be terminated considerably later and the internal combustion engine can be operated in a rich state. The rich combustion condition provides sufficient heat and non-combustible fuel to begin operation in the main oxidation catalyst. Further, in rich combustion, the fuel may be pretreated to facilitate ignition. Like much later post-injection, lambda is adequate to maximize CO and H2 production relative to HC. In order to support the ignition of at least one main exhaust gas aftertreatment unit, this measure is appropriate if it is immediately after the wastegate aftertreatment unit has ignited. When the main exhaust gas aftertreatment section ignites, typically, the state in the wastegate exhaust pipe need only be at least slightly rich in order to rapidly heat the main exhaust gas aftertreatment section. The preferred steps for cold start of the internal combustion engine will be described in detail later.

  Waste motor exhaust pipe and waste gate as a so-called “flame” to the air-cooled exhaust gas aftertreatment system by momentarily applying enough heat to start the catalytic reaction again in the main exhaust gas aftertreatment section during motoring engine operation An exhaust gas aftertreatment unit may be used. The method described in more detail above and below may also be used when restarting the main exhaust aftertreatment system.

  According to another embodiment, the turbocharger is located at or near the main exhaust outlet. In that case, the wastegate exhaust pipe of the present invention functions as a bypass of the turbocharger. By providing a bypass in the turbocharger, the following effects can be obtained. By providing a bypass in the turbocharger, heating in the main exhaust pipe is increased. This is because the turbocharger has a high thermal inertia, and therefore cools the exhaust gas during the idle or motoring engine operation mode, or consumes a large amount of thermal energy from the exhaust gas to heat from a cold start. By providing a bypass in the turbocharger, uncooled exhaust gas is provided to the main exhaust gas aftertreatment system. Low pressure turbines are usually very large and heavy, so the cooling phenomenon is increased by using a two-stage turbocharger.

  Since temperature problems only occur at certain critical temperature conditions, it is preferred that the wastegate exhaust pipe further comprises a valve adapted to control the amount of exhaust gas flowing through the wastegate exhaust pipe. As a result, the wastegate exhaust pipe is closed during the intermediate load or high load engine operation mode.

  According to another preferred embodiment, a wastegate fuel injector may be used for the burner for raising the exhaust gas temperature in the wastegate exhaust pipe. As a result, the exhaust gas temperature in the wastegate exhaust pipe becomes sufficiently high, and the overall temperature of the exhaust gas flowing through the first exhaust pipe and the wastegate exhaust pipe can be raised.

  According to another preferred embodiment, a fuel injector and / or at least one exhaust aftertreatment are arranged in close proximity to the exhaust manifold to capture the pulse energy of the exhaust pulse. The mixing of the exhaust gas and the injected fuel is promoted by the pulse energy.

  According to another preferred embodiment, the plurality of cylinders of the cylinder block are arranged at least in the first cylinder group and the second cylinder group. Preferably, each cylinder group includes an intake throttle, and each intake throttle can operate in a separable manner. Optionally, the intake manifold comprises a first intake manifold portion assigned to the first cylinder group and a second intake manifold portion assigned to the second cylinder group. With this arrangement, an inoperative cylinder group is formed by not supplying fuel to the first cylinder group during a critical temperature operation state, and an operating cylinder group is formed by supplying fuel to the second cylinder group. As described above, the internal combustion engine can be controlled. Especially high enough to maintain the temperature of the main exhaust aftertreatment system in the operating temperature range, since the overall volume of gas delivered by the inactive cylinders is reduced, which also reduces the amount of fresh air at ambient temperature. A second cylinder group operating the exhaust gas is generated.

  According to another preferred embodiment, an exhaust manifold is disposed in the exhaust manifold, the first exhaust gas flow from the first cylinder group to the first exhaust gas outlet, preferably from the second cylinder group, and preferably from the second cylinder group. And a second exhaust gas stream to the exhaust gas outlet. Since the exhaust gas from the first cylinder group and the exhaust gas from the second cylinder group are not mixed and are led to the respective exhaust gas outlets, only the high-temperature exhaust gas from the second cylinder group in operation enters the wastegate exhaust pipe. Until it goes, the temperature in the wastegate exhaust pipe further increases. In particular, the exhaust gas temperature from the active cylinder group in the low-load engine operation mode is that all cylinders are operating at low load because the power given by all cylinders is only from the active cylinder group at this time. Much higher than in the case of. This requires that the load in the active cylinder group be increased from a low load to an intermediate load or a high load, thereby increasing the temperature of the active cylinder group.

  According to another preferred embodiment, separation of the exhaust gas stream may be achieved by providing a separation element in the exhaust gas manifold. Accordingly, the exhaust gas manifold is adapted to provide a first exhaust gas manifold portion assigned to the first exhaust gas outlet and a second exhaust gas manifold portion assigned to the second exhaust gas outlet.

  According to another preferred embodiment, the exhaust gas manifold is further adapted to provide a third exhaust gas flow through the third exhaust gas pipe, the third exhaust gas pipe being assigned to the second exhaust gas manifold section. Furthermore, the third exhaust pipe is adapted to supply exhaust gas to the at least one turbocharger section. Preferably, the first and third exhaust pipes are adapted to supply exhaust gas to the same turbocharger section, preferably the turbocharger section comprises a turbine having two inlets. By using a turbine with two inlets, the overall components inside the vehicle are reduced, thereby reducing the overall weight, leading to reduced fuel consumption and increased vehicle loadability. In addition, turbines with two inlets improve turbine efficiency because turbocharger components are usually less efficient the smaller they are.

  According to another preferred embodiment, the internal combustion engine system further comprises an exhaust gas recirculation (EGR) system for recirculating at least part of the exhaust gas to the gas inlet side of the internal combustion engine, preferably the exhaust pipe is Branch off directly from the exhaust manifold, or downstream of the turbocharger section and preferably upstream of at least one part of the main exhaust aftertreatment system, most preferably upstream of at least one part of the main exhaust aftertreatment system In particular, upstream from the selective catalyst reactor, but preferably downstream from the particulate filter section for recirculating the exhaust gas that has passed through the filter, it branches off from the main exhaust gas pipe and / or the third exhaust gas pipe.

  EGR has an effect of reducing the amount of exhaust gas from an internal combustion engine, particularly the amount of nitrogen oxide in the exhaust gas. Preferably, after the sub-flow after the exhaust gas recirculation is cooled, it is sent to the gas inlet side of the EGR engine, and the air-fuel mixture is mixed with the incoming air before being introduced into the cylinder of the EGR engine. Since the gas temperature on the gas inlet side of the EGR engine rises to a level that damages the EGR engine by recirculating the re-hot exhaust gas, cooling of the circulating exhaust gas is essential for the EGR engine. In addition, exhaust gas recirculation over a wide range of 10% to 90%, depending on, for example, engine load and total mass flow engine operating mode through the EGR engine, is necessary to produce sufficient NOx reduction.

  According to another preferred embodiment, the internal combustion engine system further comprises an exhaust gas recirculation duct, wherein the exhaust gas recirculation duct branches off from the main exhaust manifold part assigned to the inoperative first cylinder group and is connected to the intake manifold. , Preferably adapted to recirculate the exhaust gas to a second intake manifold section assigned to the active second cylinder group. With this arrangement, the exhaust gas from the deactivated cylinder group, which is probably air under the circumstances under consideration, is forced into the intake manifold of the active cylinder group from the exhaust manifold of the deactivated cylinder group. The total amount of air flowing through the engine is greatly reduced. The air cooling effect during the critical temperature engine operating mode is thereby further reduced.

  According to another preferred embodiment, the internal combustion engine system is adapted to be operated with less ignitable fuel, in particular low cetane number fuel such as cetane number lower than 38 and / or 10: 1 to 30 Is adapted to ignite the fuel at a compression ratio in the range of up to 1, preferably in the range of 13: 1 to 25: 1, most preferably in the range of 15: 1 to 18: 1. As mentioned above, so-called partial premixed combustion (PPC), which operates the engine with a fuel that is difficult to ignite, also induces critical temperature operating conditions, especially when in a low load or idle engine operating mode. According to the above-described inventive feature of the internal combustion engine system, the temperature in the cylinder and / or the exhaust gas can be increased, and it can be used for a PPC engine.

  Another aspect of the present invention relates to a method for controlling an internal combustion engine system, wherein the internal combustion engine system is operated with a fuel that is difficult to ignite, and / or cold start conditions, and / or low load engine operating modes, and / or idle engine operation. During critical temperature operating conditions, such as modes and / or motoring engine operating modes, the temperature within at least a portion of the internal combustion engine system is increased. As described above, the internal combustion engine system includes a plurality of cylinders, a gas intake manifold for supplying at least air to the first and second cylinder groups, and an exhaust gas manifold for discharging exhaust gas from the cylinder block to the main exhaust gas aftertreatment system. The plurality of cylinders of the cylinder block are arranged at least in the first cylinder group and the second cylinder group.

  According to a first aspect of the invention, a preferred embodiment of the method comprises the steps of determining whether the internal combustion engine system is operating at a critical temperature state, and when the internal combustion engine system is operating at a critical temperature state. The first cylinder group is controlled so as not to operate by not supplying fuel to the cylinders of the first cylinder group, and the second cylinder group is operated by supplying fuel to the cylinders of the second cylinder group. Controlling to do.

  By sending fresh air at ambient temperature to all cylinders during the critical temperature mode of operation, fresh air is sent to only a portion of the cylinders, rather than cooling the entire internal combustion engine below the operating temperature. This has the effect of reducing the amount of fresh air. Also, operating the remaining portion of the cylinder with fuel produces hot exhaust gas, which does not increase fuel consumption excessively. The cylinders are preferably equally divided, but may not be equally divided.

  According to a preferred embodiment of the method according to the invention, each cylinder of the internal combustion engine system further comprises at least one intake valve for opening a cylinder corresponding to the intake manifold and at least for opening a cylinder corresponding to the exhaust manifold. And the method further includes controlling the exhaust valve of the at least one cylinder to at least partially open the exhaust valve at the same time as the intake valve opens. Rebreathing a predetermined amount of exhaust gas into the cylinder by raising the temperature.

  By rebreathing the exhaust gas, there is an effect that the air mass flow is reduced and the temperature of the exhaust gas system rises. Also, fuel loss is low.

  Preferably, the step of rebreathing the exhaust gas is performed not on all cylinders but on the deactivated first cylinder group, so that the temperature of the exhaust gas within the deactivated first cylinder group is increased accordingly. The rebreathing mechanism is obtained, for example, by an additional cam lobe and / or cam phase shifter if the internal combustion engine has a separate exhaust cam.

  According to another preferred embodiment, the at least one cylinder or the at least one cylinder group of the internal combustion engine system further comprises an intake throttle for controlling the amount of intake gas into the at least one cylinder or the at least one cylinder group. The method further comprises reducing the amount of intake gas into the deactivated first cylinder group, preferably to approximately zero or zero. This eliminates excessive engine throttle adjustment and significantly reduces the intake of fresh air. Excessive engine throttle adjustment without exhaust gas rebreathing reduces the pressure and draws oil from the sewage tank into the cylinder combustion chamber.

  Another aspect of the present invention is to operate an internal combustion engine system with a non-ignitable fuel and / or cold start, and / or low load engine operating mode, and / or idle engine operating mode, and / or motoring engine. A method for increasing the temperature in an internal combustion engine system during a critical temperature operating state such as an operation mode, wherein the internal combustion engine system includes a plurality of cylinders, a gas intake manifold for supplying at least air to the cylinder block, and an exhaust gas cylinder block The invention relates to a method comprising a cylinder block having an exhaust gas manifold for exhausting from a cylinder. The exhaust gas manifold has at least a main exhaust gas outlet and a waste gate exhaust gas outlet, the main exhaust gas outlet is connected to a main exhaust gas pipe for guiding the exhaust gas to the main exhaust gas aftertreatment system, and the waste gate exhaust gas outlet is a waste gate exhaust gas pipe The wastegate exhaust pipe is reconnected to the main exhaust pipe upstream of the main exhaust gas aftertreatment system and preferably at least one wastegate posttreatment section for performing catalyst treatment on the exhaust gas flowing in the wastegate exhaust pipe, preferably Comprises an oxidation catalyst such as a diesel oxidation catalyst. As an inventive feature, the method determines whether the internal combustion engine system is operating at a critical temperature state, and if the internal combustion engine system is operating at a critical temperature state, opens the wastegate exhaust pipe and at least 1 Operating two wastegate post-processing units.

As described above, the wastegate exhaust gas aftertreatment unit, particularly a diesel oxidation catalyst (DOC) or other suitable exhaust gas aftertreatment unit, uses O ₂ (oxygen) in the exhaust gas stream to convert CO (carbon monoxide) to CO. HC (hydrocarbon) is converted to H ₂ O (water) and CO ₂ into ₂ (carbon dioxide). Since this conversion process is an exothermic process, sufficient heat is generated to raise the temperature of the entire exhaust gas, and as a result, the main exhaust gas aftertreatment system and the wastegate exhaust pipe arranged below the recombining part of the main exhaust pipe. Is maintained at or brought to its operating temperature, preferably 250 ° C.

  Further, as described above, the wastegate exhaust pipe serves as a bypass of the turbocharger turbine or at least the turbocharger section disposed in the main exhaust pipe. Since the exhaust gas flowing through the wastegate exhaust pipe is not used to heat the turbocharger, the total heat of the exhaust gas increases. Further, a fuel injector or so-called post-injection performed substantially later may be used as a hydrocarbon source in the exhaust gas aftertreatment section.

  Preferably, the main exhaust gas outlet is assigned to the first cylinder group, the wastegate exhaust gas outlet and the optional third exhaust gas outlet are allocated to the second cylinder group, and the main exhaust gas outlet and the optional third exhaust gas are assigned. The outlet is connected to the first exhaust gas pipe, and the waste gate exhaust gas outlet is connected to the waste gate exhaust gas pipe.

  According to a further preferred embodiment of the method of the invention, at least one step of said rebreathing and at least one step of providing a bypass in the turbocharger by a wastegate exhaust pipe are performed. This minimizes the amount of cold air flowing through the internal combustion engine system, thus increasing the temperature in the exhaust gas.

  Preferably, the exhaust gas rebreathing is performed on a first cylinder group consisting of inactive cylinders. Thereby, there is an effect that the exhaust gas is prevented from being sent again into the waste gate exhaust pipe.

  According to another preferred embodiment, each cylinder further comprises a cylinder fuel injector for injecting at least fuel into the cylinder, and at least one cylinder of at least one cylinder, preferably of the second cylinder group. The cylinder fuel injector is controlled to inject fuel at least twice per fuel stroke, preferably the second injection is well after the first injection, preferably at least 10 cranks from the first injection. After an angle, most preferably at least 20 crank angles after the first injection.

  This so-called significantly later post-injection does not inject the entire amount of fuel at one time, but divides the fuel amount into at least two injections, and the second injection is much more effective than the first injection. Since the process is delayed, the exhaust gas temperature is increased. However, it should be noted that if the second injection is too late, the fuel will not ignite. This is necessary for air-fuel ratio adjustment, and is read herein as post-injection which takes place considerably later. See above. When the second injection is performed, the temperature of the exhaust gas is raised by raising the temperature rapidly and in a short time, so that the fuel loss falls within an allowable range.

  The post-injection performed considerably later may be performed to produce CO and H2 to ignite the oxidation catalyst at a low temperature, preferably about 150 ° C.

According to a preferred embodiment, the cold start process of the present invention (that is, the process executed after the long idle engine operation mode) includes the following steps.
1. Activating the second cylinder group with a post-injection performed later.
2. When the exhaust gas temperature in the wastegate exhaust gas pipe or the temperature in the wastegate exhaust gas aftertreatment section reaches approximately 150 ° C., it is preferable to use a suitable air-fuel ratio to maximize the CO and H2 content in the exhaust gas. And actuating the second group of cylinders with a post-injection that takes place considerably later to produce H2.
3. The operation (ignition) of the wastegate exhaust gas aftertreatment section is started at about 150 ° C. due to the presence of CO and H2 in the exhaust gas of the wastegate exhaust pipe.
4). End post-injection, which takes place considerably later, and start operation of the wastegate fuel injector.
5. This maintains the state in the wastegate exhaust pipe close to the stoichiometric mixture in order to start operation of the main exhaust aftertreatment system at approximately 150 ° C. due to the presence of CO and H2.
6). After ignition of the main exhaust gas aftertreatment system, the amount of fuel in the wastegate fuel injector is increased so that the wastegate exhaust pipe is at least slightly rich, preferably rich, in order to provide non-combustible fuel to the main oxidation catalyst. As a result, the main exhaust aftertreatment system is heated rapidly.
7). Optionally, actuate the first group of cylinders to provide sufficient power as needed.

  According to a further preferred embodiment, the first cylinder group comprises at least one first intake throttle and the second cylinder group comprises at least one second intake throttle, each intake throttle operating in a separable manner And the method further controls the first intake throttle of the first cylinder group and the second intake throttle of the second cylinder group during the critical temperature condition to provide a second cylinder group second Adjusting the first cylinder of the first cylinder group with a throttle, stronger than the cylinder.

  By adjusting the intake of air, in particular the intake of air into the first cylinder group consisting of inactive cylinders, with the throttle, the total amount of fresh air fed into the cylinder is reduced. Combining at least one step of the exhaust gas rebreathing method with the step of adjusting the intake throttle is particularly effective because it provides powerful flow control and greatly reduces the amount of fresh air in the internal combustion engine system. As a result, the exhaust gas temperature rises.

  According to another preferred embodiment, the method according to the invention further comprises the step of recirculating at least part of the exhaust gas to the gas inlet side of the internal combustion engine, the internal combustion engine system further comprising at least part of the exhaust gas in the internal combustion engine. An exhaust gas recirculation (EGR) system for recirculation on the gas inlet side of the engine, preferably the exhaust gas is downstream of the turbocharger section and preferably upstream of the main exhaust gas aftertreatment system and Alternatively, it branches off from the third exhaust pipe or directly from the exhaust manifold.

  By recirculating at least a portion of the exhaust gas during the critical temperature state, the intake of fresh air is reduced, thus increasing the exhaust gas temperature. Warm exhaust gas also flows into the cylinder and consequently into the exhaust gas, avoiding cooling of the internal combustion engine system, in particular the exhaust gas aftertreatment system.

  According to a further aspect, the present invention operates an internal combustion engine system with a non-ignitable fuel and / or cold start, and / or low load engine operating mode, and / or idle engine operating mode, and / or motor. A method of raising the temperature in an internal combustion engine system during a critical temperature operating state, such as a ring engine operating mode, wherein the internal combustion engine provides a plurality of cylinders, at least a first cylinder for providing air to a first cylinder group A first gas intake manifold section assigned to the group, at least a second gas intake manifold section assigned to the second cylinder group for supplying air to the second cylinder group, exhaust gas is discharged from the first cylinder group The first exhaust manifold part for the exhaust gas to the second cylinder group A cylinder block having a second exhaust gas manifold section for exhausting, an exhaust gas recirculation duct connecting the first exhaust gas manifold section and the second exhaust gas manifold section of the internal combustion engine system, and a plurality of cylinder blocks Further, the present invention relates to a method that is arranged at least in the first cylinder group and the second cylinder group. The method includes determining whether the internal combustion engine system is operating at a critical temperature state and, if the internal combustion engine system is operating at a critical temperature state, exhausting gas from the first cylinder group to the second cylinder group. Recirculating.

  Preferably, when the internal combustion engine system is operating at a critical temperature state, the second cylinder is controlled so as not to operate the first cylinder group by not supplying fuel to the cylinders of the first cylinder group. The method further includes controlling to operate the second cylinder group by supplying fuel to the cylinders of the group.

  Since the exhaust gas is recirculated from the exhaust gas manifold of the inactive (first) cylinder group to the gas intake manifold of the active (second) cylinder group, the second operating from the inactive first manifold section. Air is forcibly sent to the manifold section. In addition, since the air intake is adjusted by the throttle upstream of the operating gas intake manifold, the amount of forced air increases. As a result, fresh air is first sent to the deactivated cylinder group and then to the activated cylinder group, thereby passing the internal combustion engine twice. Therefore, the total amount of air flowing in the internal combustion engine is greatly reduced.

  This method is effective in that it is not necessary to perform exhaust gas rebreathing in order to increase the exhaust gas temperature. In addition, since the reused air is not necessarily mixed with the recirculated exhaust gas, the problem of accumulation of soot generated by EGR accompanied by vibration due to an unfavorable distribution as described below is avoided.

  Furthermore, another method of providing pretreated fuel is provided by using the engine mode of operation method described above. In this case, the fuel is post-injected into the inoperative first cylinder group, and if the injection timing is appropriate, the pre-processed fuel then enters the operating cylinder group with improved ignition characteristics.

  According to a further preferred embodiment, the above-described method utilizing pretreated fuel may be achieved by using exhaust gas rebreathing combined with a method of recirculating exhaust gas to an operating cylinder group. Assuming that exhaust gas rebreathing takes place in the inactive cylinder group, not in the active cylinder group, and that there is a general exhaust manifold and a general gas intake manifold for any cylinder group, Exhaust gas from an operating cylinder group may be rebreathed by an inactive cylinder group from the exhaust manifold. By performing the post-injection, which is performed at a later time, at the proper timing, a pre-processed fuel is provided, which is provided to the gas intake manifold of the operating cylinder group as a fuel with improved ignitability.

  Of course, according to another embodiment, the method may be combined with the steps of the bypass method and / or the rebreathing method described above. In particular, by combining the bypass method and the air recycling method, the thermal inertia during cold start is reduced.

  Although not all of the above are described in detail with respect to possible combinations of method steps and / or system features, the features and steps may be combined in any suitable manner without departing from the invention. Is obvious to those skilled in the art.

  Further preferred embodiments and effects are defined in the claims, drawings and description of the invention.

  Preferred embodiments of the system and method according to the present invention will be described below with reference to the accompanying drawings. The description of the drawings is regarded as a simplification of the principles of the invention and is not intended to limit the scope of the claims.

1 is a schematic diagram showing a preferred embodiment of an internal combustion engine system of the present invention. It is the schematic which shows preferable embodiment of a valve control mechanism. It is the schematic which shows preferable embodiment of a valve control mechanism. It is the schematic which shows preferable embodiment of a valve control mechanism. It is the schematic which shows preferable embodiment of a valve control mechanism. It is a temperature diagram regarding the valve mechanism of FIG. It is a graph which shows preferable embodiment of a valve control mechanism. It is a graph which shows preferable embodiment of a valve control mechanism. FIG. 6 is a temperature diagram for yet another preferred valve mechanism.

  In the following description, the same or similar functional elements are denoted by the same reference numerals.

  The schematic diagram of FIG. 1 shows an internal combustion engine 100 for use in a vehicle (not shown) with an internal combustion engine, such as a truck, bus or other vehicle. The engine system 100 includes an internal combustion engine 1 including a cylinder block 2 having, for example, six piston cylinders 4. Furthermore, the internal combustion engine 1 has an intake manifold 8 on the gas intake side 6 and an exhaust manifold 12 on the exhaust outlet side 10. The exhaust gas is guided to a turbocharger 14 including a first turbine 16 and a second turbine 18, and is sent to a front exhaust gas aftertreatment system 22 through a main exhaust gas pipe 20.

  Normally, the exhaust gas aftertreatment system 22 includes a plurality of exhaust gas aftertreatment units such as a diesel oxidation catalyst 24, a particulate filter 26, and a selective catalyst reactor (SCR) 28, for example.

  The SCR unit 26 is a means for converting nitric oxide into nitrogen and water using a catalyst. The optimum temperature range for these reactions is typically from about 250 degrees Celsius to about 450 degrees Celsius. This optimum temperature range can be easily maintained during the normal (driving) mode of operation of the engine.

  However, the exhaust gas temperature decreases during the idle engine operation mode or the motoring engine operation mode of the internal combustion engine 1. Even if the combustion is greatly reduced (as in the idle engine mode of operation) or no combustion occurs (as in the motoring engine mode of operation), fresh air at ambient temperature will cause the cylinder block 2 This is because it is sent to the intake manifold 6. This means that the internal combustion engine 1 simply sends fresh and cold air to the exhaust gas side 8 and into the exhaust aftertreatment system 22 ahead. This low-temperature air causes the temperature of the exhaust gas aftertreatment system 22 to drop sharply below the optimum operating temperature, resulting in insufficient or no exhaust gas purification, so that the required exhaust gas level can be reached. Can not.

  In order to increase the temperature of the exhaust gas flowing through the exhaust gas aftertreatment system 22, several possibilities are presented, which alone or in combination increase the temperature in at least a portion of the internal combustion engine system 100. You can do it.

  In FIG. 1, it will be clearly stated again that even if a plurality of various approaches are combined, the combination is only a preferred embodiment and does not limit the protection scope of the present invention.

  According to the present invention, a first effort to prevent a temperature drop in the exhaust gas aftertreatment system 22 is made by adding a wastegate exhaust pipe 30. The wastegate exhaust pipe 30 is preferably branched from the exhaust manifold 12, and a valve 32 for opening and closing the wastegate exhaust pipe 30 or controlling the amount of exhaust gas flowing through the wastegate exhaust pipe 30, and the fuel as exhaust gas. A fuel injector 34 for injecting the fuel into the inside and a diesel oxidation catalyst (DOC) 36 for inducing an exothermic reaction using the injected fuel may be provided.

  Instead of providing a separate waste gate oxidation catalyst 36, at least a portion of the main oxidizer 24 can be used. For this purpose, the main oxidation catalyst 24 may have at least two inlets, one for the wastegate exhaust pipe 30 and one for the main exhaust pipe 20. In that case, the waste gate exhaust pipe inlet 30 is preferably arranged upstream of the main exhaust pipe 20 inlet.

  In the embodiment shown in FIG. 1, the wastegate exhaust pipe 30 is connected to the main exhaust pipe 20 downstream of the turbocharger 14, thereby providing a bypass for the turbocharger 14. By providing a bypass in the turbocharger 14, the following effects can be obtained. When operating the internal combustion engine 1 with a fuel that is difficult to ignite and / or critical temperature conditions such as cold start conditions and / or low load engine operating modes and / or idle engine operating modes and / or motoring engine operating modes Since the turbocharger 14 is preheated, the exhaust gas is not cooled. Since the turbocharger 14 has significant thermal inertia, a large amount of thermal energy is lost in this process.

The wastegate exhaust pipe 30 functions as follows. As soon as a critical temperature condition is detected, the valve 32 opens and a predeterminable amount of exhaust gas from the exhaust manifold 12 can flow into the wastegate exhaust pipe 30. Further, the fuel injector 34 is operated, and a predeterminable amount of fuel is injected into the exhaust gas flowing through the wastegate exhaust pipe 30. The fuel injector 34 and / or valve 32 is preferably located proximate to the exhaust manifold 12. With this arrangement, the exhaust gas remains vibrated (caused by the movement of the cylinder), and this vibration has the effect of obtaining excellent mixing characteristics for mixing the exhaust gas and the injected fuel. Next, the fuel / gas mixture is guided to a small DOC unit 36, which converts carbon monoxide CO into carbon dioxide CO ₂ using oxygen O ₂ in the exhaust gas stream, and injected fuel. The hydrocarbon HC given by is converted to water H ₂ O and CO ₂ . Both reactions are exothermic reactions, and as a result, the temperature of the exhaust gas flowing through the wastegate exhaust pipe 30 is increased.

  The temperature of the exhaust gas flowing in the waste gate exhaust pipe 30 is recombined with the low temperature exhaust gas flowing in the main exhaust pipe 20 downstream of the turbocharger 14. Sufficient thermal energy is provided by the high-temperature exhaust gas from the wastegate exhaust pipe 30 to raise the total exhaust gas temperature to such an extent that the temperature of at least one of the exhaust gas aftertreatment units 24, 26 and / or 28 falls within the operating temperature range. The exhaust gas temperature at this time preferably includes a temperature higher than the operating temperature of the main diesel oxidation catalyst 24. The thermal energy provided by the DOC 24 in turn provides sufficient heat for the reaction occurring in the selective catalytic reactor 28.

  Instead of the above or in addition to the above, the exhaust gas temperature may be raised by operating only a part of the cylinder 4 during the critical temperature state. A critical temperature condition often occurs in low load or idle engine operating modes, where no or no fuel is injected into the cylinder 4 so that the cylinders in the cylinder block 2 are connected to the first cylinder group 2a and the second cylinder group 2a. The inventor of the present invention proposes to "divide" the cylinder group 2b. In the embodiment shown in FIG. 1, the cylinder is equally divided into three cylinders and three cylinders. However, the total number of cylinders may be other than six, or the cylinder division may be a cylinder division in which the number of cylinders is not equal.

  The cylinders 4a of the first cylinder group 2a are controlled not to operate, which means that no fuel is injected into the cylinders 4a. In contrast, the cylinders 4b of the second cylinder group 2b are controlled to operate. That is, only the second cylinder group 2b gives the load necessary to operate the engine in the low load mode. This means that the temperature of the exhaust gas from the second cylinder group 2b is considerably higher than the temperature of the exhaust gas from the first cylinder group 2a, and further raises the overall temperature of all exhaust gases. .

  The intake manifold 8 is likewise preferably divided into a first part 8a and a second part 8b, so that the two parts are separate (not shown) for controlling the amount of air flowing into the cylinder. Equipped with an intake throttle. In order to enhance the temperature rise effect, the first intake throttle may reduce the amount of air taken into the inactive first cylinder group 2a to substantially zero or zero. Since only a small amount of low-temperature air is allowed to pass through the cylinder, the exhaust gas temperature is raised.

  In order to further enhance the temperature rise effect, the exhaust gas manifold 12 is divided into a first portion 12a assigned to the first cylinder group 2a consisting of inactive cylinders, and a second cylinder group consisting of the operating cylinders 4b. It is also effective to divide into the second part 12b assigned to 2b. The wastegate exhaust pipe 30 is preferably arranged so as to branch from the second exhaust manifold portion 12b. By doing so, high-temperature exhaust gas is given to the DOC 36, and the exhaust gas flowing through the waste gate exhaust pipe 30 is further heated. By doing so, even if the main part of the exhaust gas flowing in the first exhaust gas pipe 20 is provided by the inactive cylinder 4, the exhaust gas flowing in the first exhaust gas pipe 20 is also heated to a desired temperature. The exhaust gas in the waste gate exhaust pipe 30 is heated as much as possible.

  The second exhaust manifold portion 12b preferably comprises an exhaust outlet that is also adapted to connect the second exhaust manifold portion 12b to the turbocharger 14. The turbine 16 of the turbocharger 14 is preferably a turbine having two inlets so that exhaust gases from the first cylinder group 2a and the second cylinder group 2b can be supplied to the same turbocharger 14. Of course, separate turbochargers can be used for each cylinder group, but this leads to an increase in the overall weight of the vehicle and the total number of vehicle parts that usually must be avoided.

  In addition to the above-described possibility for increasing the temperature, the amount of air taken into the cylinder can be reduced by recirculating the exhaust gas to the gas inlet side 6 of the internal combustion engine 1. This may be done using an exhaust gas recirculation (EGR) pipe 40 that branches off at the exhaust gas manifold 12, preferably an exhaust gas manifold section 12a assigned to the deactivated cylinder group 2a. The exhaust gas recirculation pipe 40 is further connected on the other side to a suction manifold 8, preferably a suction manifold section 8b assigned to the active cylinder group 2b.

  During the critical temperature state, such an arrangement allows fresh air to be led into the deactivated first cylinder group 2a and then to the activated second cylinder group 2b. As a result, the amount of fresh ambient air intake for the second cylinder group 2b is controlled to be substantially zero. As a result, the entire air intake amount is greatly reduced, the temperature in the cylinder 4b of the second cylinder group in operation is further increased, and then the exhaust gas temperature is further increased.

  In addition to or in lieu of the above, the EGR pipe 40 or another EGR pipe may be connected downstream of the turbocharger 14 or further downstream thereof, for example between elements of the exhaust gas aftertreatment system 22 or downstream of the elements. You may make it branch from the exhaust gas pipe 20. FIG. When the EGR pipe branches between elements of the exhaust gas aftertreatment system 22, a selective catalyst is used downstream of the particulate filter 26 to recirculate the exhaust gas after purification, but to avoid unnecessary components such as ammonia in the internal combustion engine 1. It is preferable to branch the EGR pipe upstream of the reducing unit 28.

  In order to further increase the exhaust gas temperature, the internal combustion engine 1 may be controlled to be operated by so-called post-injection. That is, the injection into the cylinder 4b that is in operation is preferably divided from one injection into at least two injections, so that the total amount of fuel injected into the cylinder is constant. For example, instead of injecting approximately 30 milligrams (mg) at a time, approximately 20 mg of fuel is injected first, and the remaining approximately 10 mg of fuel is injected considerably later. With respect to crank angle (CAD), “substantially after” means at least 10 CAD, preferably at least 20 CAD after the first injection, which is usually close to TDC. If the preceding injection timing strategy is used for very early stage injection, the later post-injection referred to here is at least 10 CAD after TDC (top dead center), preferably more than 20 CAD after TDC. Must be positioned at a large angle.

Furthermore, a so-called “subsequent post-injection” which gives unburned fuel to the exhaust gas (to bring the engine into a rich engine operating state) may be used. This engine operating state increases the amount of CO, which lowers the ignition temperature of the oxidation catalysts 36 and 24, respectively. A preferred method for operating the internal combustion engine of the present invention includes the following steps.
1. Activating the second cylinder group with a post-injection performed later.
2. When the exhaust gas temperature in the wastegate exhaust pipe 30 or the temperature in the wastegate exhaust pipe 30 reaches approximately 150 ° C., preferably using a suitable air-fuel ratio to maximize the CO and H2 content in the exhaust gas. Actuating the second group of cylinders with a post-injection that takes place significantly later to produce CO and H2.
3. The operation (ignition) of the wastegate exhaust gas aftertreatment section is started at about 150 ° C. due to the presence of CO and H2 in the exhaust gas of the wastegate exhaust pipe.
4). End post-injection, which takes place significantly later, and start the operation of the wastegate fuel injector.
5. This keeps the state in the wastegate exhaust pipe close to the stoichiometric mixture in order to start operation of the main exhaust aftertreatment system at about 150 ° C. due to the presence of CO and H2.
6). After ignition of the main exhaust gas aftertreatment system, the amount of fuel in the wastegate fuel injector is increased so that the wastegate exhaust pipe is at least slightly rich, preferably rich, in order to provide non-combustible fuel to the main oxidation catalyst. As a result, the main exhaust aftertreatment system is heated rapidly.
7). Optionally, actuate the first group of cylinders to provide sufficient power as needed.

  Hereinafter, the exhaust gas temperature rise using the above method will be briefly described.

1. Wastegate exhaust pipe (Wastegate combustion)
As described above, the wastegate exhaust pipe 30 for controlling the exhaust gas flow is added to the exhaust gas manifold 12. In the above embodiment, the wastegate exhaust pipe 30 is connected to the active cylinder 4b and guides the exhaust gas through the turbines 16 and 18 to conserve energy. In addition, the fuel injector 34 is disposed in the waste gate exhaust pipe 30 together with the small DOC 36, and surplus energy is applied to ignite the main DOC 24. In order to maintain the exhaust gas pulse by capturing the pulse energy, the fuel injector 34 and the DOC 36 must be placed in close proximity to the exhaust manifold 12. This pulse assists in mixing the fuel injected by the fuel injector 34.

  As soon as the engine starts (low temperature start state), the wastegate exhaust pipe 30 is controlled to open the valve 32 so that about 10% of the total exhaust gas flow passes through the wastegate exhaust pipe 30. The 10% of the temperature is high enough that the small DOC 36 can ignite the fuel injected by the fuel injector 34. The temperature required for this is approximately 250 ° C. In order to achieve such a temperature, the fuel must be injected into the cylinder 4b in operation. After the small DOC 36 ignites the surplus fuel, the exhaust gas sent from the wastegate exhaust pipe 30 is sufficiently warm, so that the temperature of the mixed gas obtained thereafter is close to 300 ° C., which is the temperature necessary to continue the operation of the main DOC 24. become.

  The diameter of the waste gate exhaust pipe 30 is preferably 30 millimeters (mm). The gas flow through the wastegate exhaust pipe 30 is controlled by a throttle or valve 32 on the exhaust manifold 12. The amount of fuel injected into the fuel injector 36 may be 30 mg (30 mg / cycle) per unit cycle. As soon as the main DOC 24 is sufficiently warmed, the wastegate exhaust pipe 30 closes and all exhaust gas passes through the turbocharger 14. This method can be used both when the engine is cold started and when the vehicle is operating at a low load, such as when going down a long hill.

  A simulation was carried out for the cylinder 4b in operation and a fuel injection 34 which injects further 40 mg / cycle of fuel by injecting 35 mg of fuel. As a result, the temperature of the waste gate exhaust pipe 20 reached the required temperature of 250 ° C. so that the small DOC 36 can ignite the fuel injected by the fuel injection 34. Thereafter, the overall temperature of the wastegate exhaust pipe 20 reached 270 ° C. If this temperature is not yet high enough, a larger amount of high temperature exhaust gas may be passed through the wastegate exhaust pipe 30. By changing the total flow rate of the exhaust gas passing through the wastegate exhaust gas pipe 30 from 11% to 20%, the temperature of the main exhaust gas pipe 20 increased to 290 ° C.

  This indicates that the proper temperature can be reached simply by injecting the proper amount of fuel from the fuel injector 34 and passing sufficient gas through the wastegate. Although work is lost in the process of injecting fuel into the exhaust gas, the gas is at a temperature sufficient to heat the main DOC 24 rapidly to its operating temperature.

  Table 1 shows data under the conditions of 600 rpm, 35 mg of fuel in the operating cylinder, a flow rate of 20% passing through the wastegate exhaust pipe, and 40 mg / cycle from the fuel injector 36.

2. Exhaust Gas Rebreathing and Intake Throttle As described above, the second strategy is to use an exhaust gas rebreathing mechanism called “bump” to open the exhaust valve (not shown) with the intake valve open (not shown). By lifting it up, some exhaust gas is sent back into the cylinder 4. This reduces the engine mass flow and increases the temperature in the system. As described above, this method may be performed on a portion of the cylinder to minimize fuel consumption. When the fuel is injected only into a part of the cylinder 4b, the exhaust gas temperature can be further increased by using the throttle of the cylinder 4a that is not operated so that the fuel is not injected. This is because the throttle prevents low-temperature air from being sent through the internal combustion engine 1 to the inactive cylinder 4b. Various bumps may be used. In the valve lifting profile called “Bump 0”, the exhaust valve opens and the intake valve lifting distance is maximized. In the valve lifting profiles called “bump 1”, “bump 2” and “bump 3”, the exhaust valve is reopened so as to approach the end of the lifted intake valve.

  FIG. 2 shows respective valve lift distance graphs for “Bump 0” (FIG. 2a), “Bump 1” (FIG. 2b), “Bump 2” (FIG. 2c) and “Bump 3” (FIG. 2d). ing. However, the x-axis indicates the valve lifting distance, and the y-axis indicates the crank angle. As is apparent from FIG. 2a, in the “bump”, the exhaust valve is reopened while the intake valve is being opened, and “bump 1” (in FIG. 2b) has moved one step to the right (FIG. 2d). ) Move to “Bump 3” in the same way. A graph 42 represents the lift distance of the exhaust valve, and a graph 44 represents the lift distance of the intake valve.

  Table 2 shows a summary of the results of exhaust gas rebreathing related to the exhaust gas temperature, and FIG. 3 is a graph of the results.

  FIG. 3 is a diagram in which the x-axis is the valve lifting distance and the y-axis is the crank angle.

  The above results can be further improved by using a short lifting distance in the three operating cylinders 4b. The lifting distance profiles of the three inactive cylinders are the same as described above and are shown in FIG. Here, FIG. 4a is a diagram on the left side, showing smaller bumps. FIG. 4b shows the right side of the bumps already used. The results for the wastegate exhaust pipe are shown in Table 3 below.

  Large bumps excessively slow down the flow in the system, so the exhaust gas temperature rises with smaller bumps compared to larger bumps.

  Exhaust gas rebreathing is not only a method for minimizing the flow of cold air through an inactive cylinder. Exhaust gas rebreathing may be used from the throttle on the intake pipe to the inactive cylinder 4a. The throttle may have a great influence on the mass flow. It appears that the mass flow changes from 5 g / s to 1 g / s with only a 1 kPA pressure drop. The bump size was also important when the engine was idle. As can be seen from the above table, lifting the valve by only 1 millimeter (mm) on the cylinder 4b in operation had a significant effect on the results.

3. Combination of wastegate exhaust pipe and exhaust gas rebreathing The wastegate exhaust pipe 30 allows bumps to re-feed exhaust gas into the system 100, so care must be taken when combining the above methods. This may be avoided by performing exhaust gas rebreathing in the inactive cylinder 4a without injection and lifting the valve in the operating cylinder 4b with injection. This minimizes the flow of low-temperature air through the cylinders 4a in the inactive cylinder group 2a, but the flow is sent in the correct direction in the cylinders 4b that are operating.

  If the mass flow of the wastegate exhaust pipe 30 is 13% and injection is performed at 30 mg / cycle into the cylinder 4b in operation, the inlet temperature of the wastegate exhaust pipe is injected by a small DOC 36 by the fuel injector 34. Was enough to ignite the fuel to be ignited. Otherwise, the temperature rises if more fuel is injected into the cylinder 4b in operation. By further performing injection at 20 mg / cycle from the fuel injector 34, the temperature in the main exhaust pipe 20 became 300 ° C. This is because the flow of the low-temperature air flowing through the inactive cylinder 4a is stopped by the exhaust gas rebreathing. A summary of the results is shown in Table 4 below.

  As is clear from Table 4, the exhaust gas rebreathing mechanism significantly reduces the mass flow through the cylinder. In the case of the above embodiment, the mass flow flowing in the inactive cylinder 4a is 1/10 of the mass flow flowing in the operating cylinder 4b.

  Exhaust gas rebreathing was only performed for the three inactive cylinders 4a without injection. This reduces the flow through the deactivated cylinder group 2a, thereby preventing the warm exhaust gas from the activated cylinder group 2b from being cooled. By adjusting the amount of fuel injected by the fuel injector 34, the resulting temperature in the main exhaust pipe 20 may be further adjusted.

  When the wastegate exhaust pipe 30 was closed in order to examine the influence of only the exhaust gas rebreathing mechanism, the following results were obtained.

  In this case, although the total mass flow is small, the mass flow passing through the operating and inactive cylinder groups 4a and 4b is larger. This is because the wastegate exhaust pipe 30 is closed. As described above, the exhaust gas temperature could be considerably increased only by the rebreathing mechanism.

4). Post-injection performed later As a result of the post-injection performed after the above, the exhaust gas temperature increased by about 25 ° C. as compared with the exhaust gas rebreathing mechanism in which post-injection was not performed. FIG. 5 shows the corresponding temperature curve for the cylinder 4b in operation, where the x-axis is the crank angle and the y-axis is the temperature. A summary of the results is shown in Table 6 below.

  Obviously, since 0.8 kW of power is lost in the valve, some power is again lost here to raise the temperature in the exhaust pipe. 485K in the above table is the overall temperature in the main exhaust pipe, and the external temperature of the cylinder in operation is 620K. When combined with the wastegate exhaust pipe method, a temperature higher than 530K, which is the temperature required to ignite the fuel from the fuel injector 34, could be achieved.

  As described above, the above method may be used for a partially premixed combustion (PPC) engine. PPC combustion has proven to work effectively at medium or high loads. In simple terms, PPC can be described as operating a diesel engine with low quality gasoline, which has the problem of excessive emissions of HC and CO from the engine during cold start, idle, and low loads. Of course it will occur.

  The exhaust gas rebreathing mechanism described above has been proven to improve this situation. This mechanism raises the cylinder temperature and reduces CO and HC emissions. Furthermore, HC and CO emissions are not a problem if the exhaust gas aftertreatment system is in operation. However, if the catalyst temperature is below 250 ° C., the conversion efficiency decreases to an unacceptable level. As a result, the temperature of the exhaust gas aftertreatment system must be kept above 250 ° C. during the low load engine operating mode.

According to the present invention, at the time of low load, the cylinders of the PPC engine are controlled to be divided into the inactive first cylinder group 2a and the active second cylinder group 2b. Additionally or alternatively, the intake manifold 8 is also divided into two parts 8a and 8b so that each cylinder group 2a and 2b can have a separate throttle. In order to reduce the air flow through the deactivated cylinder 4a as much as possible without overheating the nozzle or excessive throttle adjustment, the PPC engine is then operated to perform at least one of the following steps: .
-Enable exhaust gas rebreathing in all cylinders.
-Slightly throttle the cylinder 4b in operation to raise the combustion temperature.
-Throttle adjustment of the deactivated cylinder 4a is tighter than the activated cylinder 4b in order to reduce the low-temperature air fed into the deactivated cylinder 4a.

  As a result of this measure, the load increases enough to move from the zone where the PPC problem occurs (in the active cylinder group) and the temperature rises in the active cylinder group, which helps solve the low load problem of PPC. This measure also increases the exhaust gas temperature for activating the catalyst for CO and HC oxidation by increasing the exhaust gas temperature from the operating cylinder group 4b and / or heating the air in the inactive cylinder group 4a. It will help.

  As already mentioned, the exhaust gas pulse decreases rapidly as the load decreases. By increasing the load on one cylinder group, it is possible to increase the number of better pulses in the flow through the turbine. This improves the heat recovery of the turbocharger within a low load range of about 10 to 25%. If the load exceeds 25%, this corresponds to a 50% load on the active cylinder, so the effort to divide the cylinder group would not be feasible.

  In summary, different aspects of the method and / or the internal combustion engine system of the present invention may be used during critical temperature engine operating conditions such as PPC, cold start, low load, idle and / or motoring engine operating modes. It is possible to raise the exhaust gas temperature. The internal temperature of the cylinder itself and / or the exhaust gas temperature will rise significantly during the critical temperature engine operating conditions, so that the temperature of the exhaust gas aftertreatment system will quickly rise to the operating temperature and reduce its operating temperature. It will be possible to maintain for a long time.

100 Internal Combustion Engine System 1 Internal Combustion Engine 2 Cylinder Block 2a Inactive Cylinder Group 2b Active Cylinder Group 4 Cylinder 4a Inactive Cylinder 4b Active Cylinder 6 Gas Inlet 8 Intake Manifold 8a Inactive Intake Manifold 8b Operated Intake manifold section 10 Exhaust outlet side 12 Exhaust manifold 12a Inactive exhaust manifold section 12b Exhaust exhaust manifold section 14 Turbocharger 16 First turbine 18 Second turbine 20 First / main exhaust pipe 22 After exhaust Treatment System 24 Main Diesel Oxidation Catalyst 26 Particulate Filter 28 Selective Catalytic Reactor 30 Wastegate Exhaust Pipe 32 Valve 34 Fuel Injector 36 Small Diesel Oxidation Catalyst 40 EGR Pipe 42 Exhaust Valve Lifting Distance 44 Intake Valve Lifting Distance

Claims (5)

A state in which the internal combustion engine of the internal combustion engine system (100) having the exhaust gas aftertreatment system (22) is operated with a low cetane number non-ignitable fuel, or a cold start state, or the engine operating mode is a low load engine operating mode, or In at least one of the above states or engine operating modes, an idle engine operating mode or a motoring engine operating mode in which the engine is operating at a speed above a certain rotational speed but no fuel is injected into the engine. A method of increasing the temperature of the exhaust gas aftertreatment system (22) during a critical temperature engine operating state where the operating temperature of the exhaust gas aftertreatment system (22) cannot be maintained,
The internal combustion engine system includes a plurality of cylinders (4), a gas intake manifold (8, 8a, 8b) for supplying at least air to the first cylinder group (2a) and the second cylinder group (2b), and exhaust gas. The cylinder block (2) having an exhaust gas manifold (12, 12a, 12b) for discharging from the cylinder block (2) to the main exhaust gas aftertreatment system;
The exhaust gas manifold (12, 12a, 12b) includes at least a main exhaust gas outlet and a waste gate exhaust gas outlet, and the main exhaust gas outlet is assigned to the first cylinder group (2a), and the waste gate exhaust gas outlet Is assigned to the second cylinder group (2b),
The main exhaust gas outlet is connected to a main exhaust gas pipe (20) for guiding exhaust gas to the exhaust gas aftertreatment system (22), the waste gate exhaust gas outlet is connected to a waste gate exhaust gas pipe (30);
The wastegate exhaust pipe (30) is reconnected to the main exhaust pipe (20) upstream of the exhaust gas aftertreatment system (22), and performs catalytic treatment on the exhaust gas flowing through the wastegate exhaust pipe (30). At least one wastegate post-processing section (36) for
The method
Determining whether the internal combustion engine system (100) is operating in the critical temperature engine state;
Opening the wastegate exhaust pipe (30) and operating the at least one wastegate aftertreatment (36) when the internal combustion engine system (100) is operating in the critical temperature engine state; Including a fuel injector (34) disposed within the wastegate exhaust pipe (30) for injecting fuel into the exhaust gas flowing through the wastegate exhaust pipe (30) during the critical temperature engine condition. The fuel injector (34) is arranged upstream of the wastegate aftertreatment (36). Each cylinder (4) further comprises a cylinder fuel injector for injecting at least fuel into the cylinder (4),
The cylinder fuel injectors of at least one cylinder of the second cylinder group (2b) are controlled to inject fuel at least twice per fuel stroke;
The method of claim 1, wherein the second injection is performed at least 20 crank angles after the first injection. The first cylinder group (2a) includes at least one first intake throttle, the second cylinder group (2b) includes at least one second intake throttle, and each intake throttle can be operated individually. And
The method further controls the first intake throttle of the first cylinder group (2a) and the second intake throttle of the second cylinder group (2b) during the critical temperature engine state, 3. The method according to claim 1, comprising the step of adjusting the first intake throttle of the first cylinder group (2 a) more strongly than the second intake throttle of the second cylinder group (2 b). . Recirculating at least a portion of the exhaust gas to the gas inlet side of the internal combustion engine;
The internal combustion engine system (100) further includes an exhaust gas recirculation (EGR) pipe (40) for recirculating at least part of the exhaust gas to the gas inlet side of the internal combustion engine (1).
The exhaust gas branches from the main exhaust pipe (20) downstream of the turbocharger section (14) or upstream of the exhaust gas aftertreatment system (22), or directly from the exhaust manifold (12, 12a, 12b). The method according to claim 1, which branches.   A vehicle comprising an internal combustion engine system for performing the method according to claim 1.

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