JP2020143645A - Control device for internal combustion engine - Google Patents

Abstract

To provide a control device for an internal combustion engine capable of more appropriately suppressing drop of a torque with a switching transition period in which the number of superchargers to be used for supercharge control is switched, without adding a new apparatus such as an electric motor and without impairing durability or reliability of the superchargers in an internal combustion engine system comprising multiple superchargers.SOLUTION: A control device 70 comprises: supercharge switching means 71A for switching the number of superchargers to be used for supercharge control; total lost torque estimation means 71B for estimating a total lost torque caused by drop of supercharge during a switching transition period just after the number of superchargers is switched; first required torque calculation means 71C for calculating a first required torque corresponding to the estimated total lost torque; injection start timing correction amount calculation means 71D for calculating an injection start timing correction amount based on the calculated first required torque; and injection start timing change means 71E for making injection start timing of a fuel earlier than ordinary injection timing based on the calculated injection start timing correction amount.SELECTED DRAWING: Figure 1

Description

The present invention relates to an internal combustion engine control device that controls an internal combustion engine system having a plurality of turbochargers.

Some internal combustion engines mounted on vehicles and construction machines in recent years are equipped with a supercharger (so-called turbocharger) that supercharges using the energy of exhaust gas in order to obtain a larger output. In addition, some internal combustion engines are equipped with two or more turbochargers. For example, in an internal combustion engine equipped with two superchargers, a first supercharger and a second supercharger, a first supercharger and a second supercharger are arranged in series, and a first supercharger. Some turbochargers and a second turbocharger are arranged in parallel.

An internal combustion engine having two turbochargers arranged in series or in parallel can improve the response and obtain torque from a low rotation range as compared with an internal combustion engine having only one large turbocharger. There are merits such as. However, in an internal combustion engine equipped with two turbochargers, depending on the operating conditions, there are cases where only one turbocharger is supercharged and cases where two turbochargers are supercharged. , Need to be switched. In the transitional period when the turbocharger is switched from one to two (or from two to one), a temporary drop in supercharging occurs, and a drop in torque occurs due to the drop in supercharging. The drop in torque is a level that the user can clearly experience, and it gives the user a sense of discomfort, which is not preferable. Therefore, it is desired to suppress the amount of torque drop during the switching transition period in which the number of turbochargers used for supercharging control is switched.

For example, Patent Document 1 discloses an internal combustion engine system control device that controls an internal combustion engine in which a first supercharger and a second supercharger are arranged in series. In Patent Document 1, a cylinder pressure sensor is provided in each cylinder, and the cylinder pressure sensor acquires the cylinder pressure of the cylinder that has reached the exhaust process, and based on the acquired cylinder pressure, the first turbocharger and the second supercharger and the second The parameters related to the fluctuation of the exhaust pressure due to the change of the exhaust supply state to the turbocharger are acquired. Then, based on the acquired parameters, the pump loss before switching the supercharger (loss due to the pump operation of the intake and exhaust of the piston) and the pump loss during the transition transition period of the supercharger are calculated and pumped. We are looking for a loss step. Then, the torque correction injection amount is calculated based on the obtained pump loss step, and the fuel injection amount is increased (the torque is increased) to suppress the fluctuation of the torque due to the pump loss.

Further, Patent Document 2 discloses an internal combustion engine control device that controls an internal combustion engine in which a first supercharger and a second supercharger are arranged in parallel. The first supercharger and the second supercharger described in Patent Document 2 are provided with an intake bypass passage and an intake bypass valve for temporarily performing a serial supercharging operation. The control device in Patent Document 2 has a transitional period for switching from a single turbo mode (supercharging with only one supercharger) to a twin turbo mode (supercharging with two superchargers). Then, in the switching transition period, after the main injection, which is the main part of the combustion process, post-injection is performed to inject a small amount of fuel into the combustion gas in the combustion process again to raise the exhaust temperature and improve the expansion rate of the exhaust. There is. As a result, the exhaust energy is increased (that is, the start-up of the turbine speed of the turbocharger is accelerated) during the transitional period of switching of the turbocharger, and the decrease in supercharger (decrease in torque) is suppressed.

Further, Patent Document 3 discloses an internal combustion engine supercharging system that controls an internal combustion engine in which a first supercharger and a second supercharger are arranged in parallel. In Patent Document 3, the second supercharger is configured to be driven by the exhaust energy of the internal combustion engine and also to be driven by an electric motor. Then, the control device in Patent Document 3 sets the electric motor in the switching transition period in which the state of supercharging only with the first supercharger is switched to the state of supercharging with the first supercharger and the second supercharger. It is used to instantly start up the rotation speed of the second supercharger and suppress the drop in supercharging (drop in torque).

Japanese Unexamined Patent Publication No. 2010-190070 Japanese Unexamined Patent Publication No. 2010-151087 Japanese Unexamined Patent Publication No. 2010-408225

In the system described in Patent Document 1, it is assumed that the torque drop during the switching transition period of the turbocharger is substantially due to the pump loss torque. However, as a result of various experiments and simulations, it has become clear that the cooling loss torque due to the increase in the amount of heat lost to the cylinder and piston due to the drop in supercharging is larger than the pump loss torque than the pump loss torque. It was. That is, even if the torque is increased so as to compensate for the pump loss torque, the torque is insufficient. Further, although the fuel injection amount (main injection amount) is increased in order to increase the torque, it is not so preferable because it accompanies a decrease in fuel consumption. Furthermore, it is necessary to provide an in-cylinder pressure sensor in each cylinder, which is not very preferable because it involves a significant modification of the cylinder (or cylinder head) as well as an increase in cost.

In the system described in Patent Document 2, post injection is performed during the transitional period of switching of the turbocharger. However, it seems that it is somehow within the expansion ratio constraint of the turbocharger during acceleration (the constraint to ensure durability and reliability, such as the upper limit constraint of "turbine upstream pressure / turbine downstream pressure"). In such a situation, increasing the expansion ratio of the exhaust gas is not so preferable from the viewpoint of durability and reliability, although it is temporary. If the expansion ratio of the exhaust gas is increased by performing post injection, the ratio of the upstream pressure to the downstream pressure of the turbocharger turbine becomes large, which may affect the durability and reliability of the turbine.

In the system described in Patent Document 3, since an electric motor is added to the second supercharger, it is not very preferable because it is costly and increases in size and weight.

The present invention was devised in view of these points, and in an internal combustion engine system having a plurality of turbochargers, the durability of the turbocharger and the durability of the turbocharger can be improved without adding new equipment such as an electric motor. The challenge is to provide a control device for an internal combustion engine that can more appropriately suppress the drop in torque due to the switching transition period in which the number of turbochargers used for supercharging control is switched without impairing reliability. To do.

In order to solve the above problems, the first invention of the present invention detects the operating state of an internal combustion engine having a plurality of turbochargers, and fuels to be injected into the cylinder of the internal combustion engine based on the detected operating state. In the control device of the internal combustion engine that controls the amount, the control device starts injection of fuel at a normal injection timing, which is a predetermined timing at which the piston of the internal combustion engine is near the position of the compression top dead point, and the cylinder. The generated torque can be adjusted by adjusting the amount of fuel injected inward, and the generated torque can be further adjusted by adjusting the fuel injection start timing before and after the normal injection timing. Supercharging switching means that switches the number of superchargers used for supercharging control according to the operating state of the internal combustion engine, and supercharging immediately after switching the number of superchargers using the supercharging switching means. In the switching transition period from the state in which the turbocharging occurs to the target supercharging state, the total loss torque estimating means for estimating the total loss torque, which is the loss of torque due to the supercharging drop, and the above-mentioned In the switching transition period, the first required torque calculation means that calculates the first required torque according to the estimated total loss torque, and the injection start timing correction based on the calculated first required torque in the switching transition period. The injection start time correction amount calculating means for calculating the amount and the injection start time change for making the fuel injection start time earlier than the normal injection timing based on the calculated injection start time correction amount in the switching transition period. A control device for an internal combustion engine having means and means.

Next, the second invention of the present invention is the control device of the internal combustion engine according to the first invention, and the total loss torque estimation means in the control device is the internal combustion engine in the switching transient period. The cooling loss torque, which is the torque lost based on the increase in the heat loss due to the drop in supercharging in the heat loss of the piston and the cylinder, is estimated, and the total loss torque is based on the estimated cooling loss torque. It is a control device of an internal combustion engine that estimates.

Next, the third invention of the present invention is the control device for the internal combustion engine according to the second invention, and the total loss torque estimation means in the control device further increases the internal combustion engine during the switching transition period. The exhaust loss torque, which is the torque gained based on the reduction in the exhaust loss due to the drop in supercharging in the exhaust loss based on the exhaust flow rate from the cylinder of the engine, is estimated, and the estimated cooling loss torque and the said This is an internal combustion engine control device that estimates the total loss torque based on the exhaust loss torque.

Next, the fourth invention of the present invention is the control device for the internal combustion engine according to the third invention, and the total loss torque estimation means in the control device further increases the internal combustion engine during the switching transition period. The pump loss torque, which is the torque lost based on the increase in the pump loss due to the drop in supercharging in the pump loss based on the pump operation of the intake and exhaust by the piston of the engine, is estimated, and the estimated cooling loss It is an internal combustion engine control device that estimates the total loss torque based on the torque, the exhaust loss torque, and the pump loss torque.

Next, the fifth invention of the present invention is a control device for an internal combustion engine according to any one of the first to fourth inventions, wherein the control device is in the cylinder of the internal combustion engine. By adjusting the fuel pressure, which is the pressure of the fuel to be injected into the engine, and adjusting the fuel injection time width, the generated torque can be further adjusted, and in the switching transition period, it is made earlier based on the injection start time correction amount. The first compensation torque calculating means for calculating the first compensation torque, which is the torque increased according to the fuel injection start timing, and the first compensation torque are insufficient with respect to the first required torque in the switching transition period. The fuel pressure correction amount is calculated based on the second required torque calculating means for calculating the second required torque, and the second required torque when the second required torque is present in the switching transition period. It is a control device for an internal combustion engine having a fuel pressure correction amount calculating means and a fuel pressure changing means for increasing the fuel pressure based on the calculated fuel pressure correction amount in the switching transition period.

Next, the sixth invention of the present invention is the control device for the internal combustion engine according to the fifth invention, and the control device is said to have the second required torque in the switching transition period. When there is a second compensation torque calculation means that calculates a second compensation torque, which is a torque increased according to the fuel pressure increased based on the fuel pressure correction amount, and the second required torque in the switching transition period. When there is the third required torque in the switching transient period and the third required torque calculating means for calculating the third required torque, which is the torque insufficient for the second supplement torque with respect to the second required torque. In addition, the fuel correction amount calculating means that calculates the fuel correction amount based on the third required torque and the amount of fuel injected into the cylinder based on the calculated fuel correction amount in the switching transition period are increased. , A control device for an internal combustion engine.

According to the first invention, in the switching transition period immediately after switching the number of turbochargers used for supercharging control, the first required torque according to the total loss torque is calculated and based on the first required torque. Calculate the injection start time correction amount. Then, based on the injection start timing correction amount, the fuel injection start timing is made earlier than the normal injection timing. That is, the fuel injection start time is advanced without changing the fuel amount. In general, the peak position of the expansion pressure due to the combustion of the fuel injected into the cylinder is adjusted at the injection start timing so that the piston is at a position slightly lower than the compression top dead center for various reasons. ing. Therefore, by advancing the injection start timing in the switching transition period, the peak position of the expansion pressure is set so that the piston is closer to the compression top dead center. As a result, the torque generated by the internal combustion engine can be increased without increasing the amount of fuel. Therefore, it is possible to more appropriately suppress the drop in torque due to the switching transition period in which the number of turbochargers used for supercharging control is switched without adding a new device such as an electric motor. Moreover, since the fuel injection amount is not changed, the exhaust flow rate and the exhaust pressure are almost the same. Therefore, it is possible to more appropriately suppress the drop in torque due to the switching transition period in which the number of turbochargers used for supercharging control is switched without impairing the durability and reliability of the turbocharger.

In various experiments and simulations, it has been found that the torque loss due to the drop in supercharging during the switching transition period of the turbocharger is the cooling loss torque, the exhaust loss torque, and the pump loss torque. Among them, it has become clear that the cooling loss torque is dominant (the largest proportion). According to the second invention, by estimating the total loss torque based on the cooling loss torque instead of the pump loss torque, it is possible to estimate the total loss torque having a more appropriate magnitude.

According to the third invention, the total loss torque can be estimated more accurately by estimating the total loss torque based on the cooling loss torque and the exhaust loss torque.

According to the fourth invention, the total loss torque can be estimated more accurately by estimating the total loss torque based on the cooling loss torque, the exhaust loss torque, and the pump loss torque.

When the fuel injection start time is advanced to increase the generated torque, the injection start time cannot be advanced indefinitely and there is a limit, so the torque that can be increased (first compensation torque) is also limited. According to the fifth invention, if the first compensation torque due to the earlier fuel injection start timing is still insufficient by the second required torque with respect to the first required torque, the fuel pressure is increased. To shorten the injection time width. That is, by shortening the time width for injecting fuel without changing the amount of fuel, the injection can be completed earlier. In the cylinder, combustion proceeds according to the amount of fuel injected and a force is generated to push down the piston by the expansion pressure, but when the injection time width is long, the piston position burns to a position greatly lowered from top dead center. Will continue, which is inefficient. Even if the amount of fuel is the same, if the fuel pressure is increased and the injection time width is shortened, the fuel is injected at the position where the piston position is closer to the top dead center, and the combustion ends at the position where the piston position is closer to the top dead center. Can be made. Therefore, since the force for pushing down the piston can be generated by the expansion pressure at the position where the position of the piston is closer to the top dead center, the generated torque can be increased without increasing the amount of fuel.

When the fuel pressure is increased to increase the generated torque, the fuel pressure cannot be increased indefinitely and there is a limit, so there is also a limit to the torque that can be increased (second compensation torque). According to the sixth invention, if the second compensation torque due to the increase in the fuel pressure with respect to the second required torque is still insufficient by the third required torque, the fuel amount is increased. Since neither the first compensation torque, which is increased by advancing the fuel injection start time, or the second compensation torque, which is increased by increasing the fuel pressure, does not change the fuel amount, the amount is increased in the sixth invention. The amount of fuel to be made (fuel correction amount) can be small. Therefore, it is possible to suppress a decrease in fuel consumption as compared with a case where the generated torque is increased only by increasing the fuel amount without adjusting the fuel injection start timing and the fuel pressure.

It is a figure explaining the example of the whole schematic structure of the system (the system including two superchargers) which has the control device of the internal combustion engine of this invention. Control to switch from single supercharging control (supercharging only with the first supercharger) to twin supercharging control (supercharging with the first supercharger and the second supercharger), and the drop in supercharging during the transition transition period. It is a figure explaining an example of a drop of torque. It is a figure explaining the total loss torque. It is a flowchart explaining the example of the processing procedure (processing procedure for obtaining each correction amount) of a control device. It is a flowchart explaining an example of the processing procedure (processing procedure of supercharging control switching processing) of a control device. It is a flowchart explaining the example of the processing procedure (processing procedure which reflects the injection start time correction amount in control) of a control device. It is a flowchart explaining an example of the processing procedure (processing procedure which reflects a fuel pressure correction amount in control) of a control device. It is a flowchart explaining an example of the processing procedure (processing procedure which reflects a fuel correction amount in control) of a control device. It is an image diagram explaining an example of an expansion pressure state in a cylinder, a fuel injection timing, and a fuel pressure state when a torque drop occurs in a switching transition period (before correction). An example of the expansion pressure state in the cylinder, the fuel injection timing, and the fuel pressure state when the fuel injection start time is earlier than the state shown in FIG. 9 (first compensation) will be described. It is an image diagram. FIG. 5 is an image diagram illustrating an example of an expansion pressure state in a cylinder, a fuel injection timing, and a fuel pressure state when the fuel pressure is further increased (second compensation) from the state shown in FIG. 10. It is an image diagram explaining an example of an expansion pressure state in a cylinder, a fuel injection timing, and a fuel pressure state when the amount of fuel is further increased from the state shown in FIG. 11 (third compensation). It is a figure explaining how the drop in output torque shown in FIG. 2 is compensated by the first compensation that advances the fuel injection start time, the second compensation that raises the fuel pressure, and the third compensation that increases the fuel amount. is there.

● [Example of schematic configuration of the entire internal combustion engine system (Fig. 1)]
Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. First, an example of a schematic configuration of the entire internal combustion engine system including the internal combustion engine control device 70 will be described with reference to FIG. In the description of the present embodiment, an internal combustion engine 10 (for example, a diesel engine) mounted on a vehicle will be used as an example of the internal combustion engine. Further, in the example of the internal combustion engine system shown in FIG. 1, two turbochargers, a first supercharger 31 and a second supercharger 32, are arranged in parallel, but the intake bypass pipe 11CB and the intake bypass valve 61 are arranged in parallel. By having the above, it is possible to perform a series supercharging operation of the second supercharger 32 and the first supercharger 31.

Hereinafter, the entire system will be described in order from the intake side to the exhaust side. An intake air flow rate detecting means 21 (for example, an intake air flow rate sensor) is provided on the inflow side of the intake pipe 11A. The intake flow rate detecting means 21 outputs a detection signal according to the flow rate of the air sucked by the internal combustion engine 10 to the control device 70. The outflow side of the intake pipe 11A is bifurcated into the intake pipes 11B1 and 11B2, and is connected to the inflow side of the intake pipe 11B1 and the inflow side of the intake pipe 11B2.

The outflow side of the intake pipe 11B1 is connected to the inflow side of the compressor 31A of the first supercharger 31 (first turbocharger). Further, the outflow side of the intake bypass pipe 11CB is connected in the middle of the intake pipe 11B1. The outflow side of the compressor 31A is connected to the inflow side of the intake pipe 11C1, and the outflow side of the intake pipe 11C1 is merged with the outflow side of the intake pipe 11C2 and connected to the inflow side of the intake pipe 11D. The compressor 31A is rotationally driven by the turbine 31B, compresses the air sucked from the intake pipe 11B1, and discharges (supercharges) the air to the intake pipe 11C1.

The outflow side of the intake pipe 11B2 is connected to the inflow side of the compressor 32A of the second supercharger 32 (second turbocharger). The outflow side of the compressor 32A is bifurcated into the intake pipe 11C2 and the intake bypass pipe 11CB, and is connected to the inflow side of the intake pipe 11C2 and the inflow side of the intake bypass pipe 11CB. The outflow side of the intake pipe 11C2 merges with the outflow side of the intake pipe 11C1 and is connected to the inflow side of the intake pipe 11D. Further, the intake pipe 11C2 is provided with an intake switching valve 62 that opens and closes the intake pipe 11C2 based on a control signal from the control device 70. The outflow side of the intake bypass pipe 11CB is connected to the intake pipe 11B1. Further, the intake bypass pipe 11CB is provided with an intake bypass valve 61 that opens and closes the intake bypass pipe 11CB based on a control signal from the control device 70.

The turbine 32B that rotationally drives the compressor 32A is rotationally driven by the energy of the exhaust gas when the exhaust switching valve 63 is opened. The exhaust switching valve 63 opens and closes the exhaust pipe 12B2 based on the control signal from the control device 70. When the exhaust switching valve 63 is opened and the turbine 32B is rotationally driven, the control device 70 opens one of the intake switching valve 62 and the intake bypass valve 61 and closes the other. Further, when the exhaust switching valve 63 is closed, the control device 70 closes both the intake switching valve 62 and the intake bypass valve 61.

When the compressor 32A is rotationally driven by the turbine 32B, when the intake switching valve 62 is in the open state and the intake bypass valve 61 is in the closed state, the air sucked from the intake pipe 11B2 is compressed and discharged to the intake pipe 11C2 ( Supercharge). Further, when the compressor 32A is rotationally driven by the turbine 32B, when the intake switching valve 62 is in the closed state and the intake bypass valve 61 is in the open state, the air sucked from the intake pipe 11B2 is compressed to the intake bypass pipe 11CB. Discharge (supercharge).

The inflow side of the intake pipe 11D is connected to the outflow side of the intake pipe 11C1 and the outflow side of the intake pipe 11C2, and the outflow side of the intake pipe 11D is connected to the inflow side of the intake manifold 11E. In any one of the intake pipe 11C1, the intake pipe 11D, and the intake manifold 11E, which is on the downstream side of the compressor 31A of the first supercharger 31, the supercharging pressure detecting means 22A (for example, a pressure sensor) for detecting the supercharging pressure is used. ) Is provided. The supercharging pressure detecting means 22A outputs a detection signal corresponding to the pressure of the supercharged intake air to the control device 70.

The outflow side of the intake manifold 11E is connected to each cylinder of the internal combustion engine 10.

The internal combustion engine 10 has a plurality of cylinders, and injectors 43A to 43H are provided in each cylinder. Fuel is supplied to the injectors 43A to 43H from the common rail 42 via a fuel pipe, and the injectors 43A to 43H are driven by a control signal from the control device 70 to inject fuel into the respective cylinders.

Fuel is supplied to the common rail 42 from a fuel pressure adjusting pump 41 driven based on a control signal from the control device 70. Further, the common rail 42 is provided with a fuel pressure detecting means 23 (for example, a pressure sensor) for detecting the pressure of the fuel in the common rail 42. The fuel pressure detecting means 23 outputs a detection signal corresponding to the detected fuel pressure to the control device 70. The control device 70 controls the fuel pressure adjusting pump 41 so that the fuel pressure based on the detection signal from the fuel pressure detecting means 23 becomes the target fuel pressure.

The internal combustion engine 10 is provided with a rotation detecting means 25 (for example, a rotation sensor), a coolant temperature detecting means 24 (for example, a temperature sensor), and the like. The rotation detecting means 25 outputs a detection signal corresponding to the rotation speed of the crankshaft of the internal combustion engine 10 (that is, the engine rotation speed) to the control device 70. The coolant temperature detecting means 24 detects the temperature of the cooling coolant circulated in the internal combustion engine 10 and outputs a detection signal corresponding to the detected temperature to the control device 70.

The inflow side of the exhaust manifolds 12A1 and 12A2 is connected to the exhaust side of the internal combustion engine 10, the inflow side of the exhaust pipe 12B1 is connected to the outflow side of the exhaust manifold 12A1, and the inflow side of the exhaust pipe 12B2 is connected to the outflow side of the exhaust manifold 12A2. It is connected. The outflow side of the exhaust pipe 12B1 is connected to the inflow side of the turbine 31B of the first supercharger 31, and the outflow side of the exhaust pipe 12B2 is connected to the inflow side of the turbine 32B of the second supercharger 32. Further, the exhaust pipe 12B2 is provided with an exhaust switching valve 63 that opens and closes the exhaust pipe 12B2 based on a control signal from the control device 70. Further, the exhaust pipe 12B1 and the exhaust pipe 12B2 are connected to an exhaust bypass pipe 12BB that guides the exhaust gas in the exhaust pipe 12B2 to the exhaust pipe 12B1 when the exhaust switching valve 63 is in the closed state.

The inflow side of the exhaust pipe 12C1 is connected to the outflow side of the turbine 31B of the first supercharger 31, and the outflow side of the exhaust pipe 12C1 is connected to the inflow side of the oxidation catalyst 51. The inflow side of the exhaust pipe 12C2 is connected to the outflow side of the turbine 32B of the second supercharger 32, and the outflow side of the exhaust pipe 12C2 is connected in the middle of the exhaust pipe 12C1. Further, the exhaust pipe 12C1 includes an exhaust pressure detecting means 22B (for example, a pressure sensor) for detecting the exhaust pressure in the exhaust pipe 12C1 and an exhaust temperature detecting means 26 (for example, a temperature sensor) for detecting the temperature of the exhaust in the exhaust pipe 12C1. Etc. are provided. The exhaust pressure detecting means 22B outputs a detection signal corresponding to the detected pressure to the control device 70, and the exhaust temperature detecting means 26 outputs a detection signal corresponding to the detected temperature to the control device 70.

The turbine 31B of the first supercharger 31 is provided with a variable nozzle 31C capable of adjusting the flow velocity of the exhaust gas that rotationally drives the turbine 31B, and the variable nozzle 31C is a nozzle that operates in response to a control signal from the control device 70. It is operated by the drive means 31D (for example, an electric motor). Further, the nozzle opening degree detecting means 31E (for example, a rotation angle sensor) outputs a detection signal according to the operating state of the nozzle driving means 31D (in this case, the rotation angle of the electric motor) according to the opening degree of the variable nozzle 31C. Output to. The control device 70 controls the nozzle driving means 31D so that the opening degree of the variable nozzle 31C obtained based on the detection signal from the nozzle opening degree detecting means 31E becomes the target nozzle opening degree. The same applies to the variable nozzle 32C, the nozzle driving means 32D, and the nozzle opening degree detecting means 32E of the turbine 32B of the second supercharger 32, and thus the description thereof will be omitted.

The outflow side of the oxidation catalyst 51 is connected to the inflow side of the DPF 52 (particulate particulate filter). The oxidation catalyst 51 oxidizes and purifies HC (hydrocarbon) and CO (carbon monoxide) in the exhaust gas of the internal combustion engine 10.

The outflow side of the DPF 52 is connected to the inflow side of the urea SCR53, and the DPF 52 collects fine particles in the exhaust gas. Further, the DPF 52 is provided with a differential pressure detecting means 22C (for example, a differential pressure sensor) for detecting the pressure difference between the inflow side and the outflow side of the DPF 52. The differential pressure detecting means 22C outputs a detection signal corresponding to the pressure difference between the inflow side and the outflow side of the DPF 52 to the control device 70. The control device 70 can estimate the amount of fine particles deposited on the DPF 52 from the differential pressure based on the detection signal from the differential pressure detecting means 22C.

The urea SCR53 uses urea injected from a urea water addition valve (not shown) to reduce and purify NOx (nitrogen oxides) in the exhaust gas.

The control device 70 has at least a control means 71 (CPU) and a storage means 73. The control device 70 detects the operating state of an internal combustion engine (internal combustion engine system) having a plurality of turbochargers, and controls the amount of fuel injected into the cylinder of the internal combustion engine based on the detected operating state. The control device 70 (control means 71) is not limited to the detection means and the actuator shown in FIG. 1, and detects the operating state of the internal combustion engine 10 based on the detection signals from various detection means including the above-mentioned detection means. .. The control device 70 (control means 71) includes various injectors 43A to 43H, an intake bypass valve 61, an intake switching valve 62, an exhaust switching valve 63, nozzle driving means 31D and 32D, and a fuel pressure adjusting pump 41. Control the actuator of. The storage means 73 is, for example, a storage device such as a Flash-ROM, and stores programs, data, and the like for executing a process described later. The control means 71 includes a supercharging switching means 71A, a total loss torque estimating means 71B, a first required torque calculating means 71C, an injection start time correction amount calculating means 71D, an injection start time changing means 71E, and a first compensation torque calculating means. 71F, 2nd required torque calculation means 71G, fuel pressure correction amount calculation means 71H, fuel pressure changing means 71I, 2nd compensation torque calculation means 71J, 3rd required torque calculation means 71K, fuel correction amount calculation means 71L, fuel amount change It has various processing means such as means 71M, which will be described later.

The atmospheric pressure detecting means 22D (for example, an atmospheric pressure sensor) is provided in, for example, the control device 70, and outputs a detection signal corresponding to the atmospheric pressure around the control device 70 to the control device 70.

The accelerator pedal depression amount detecting means 27 (for example, an accelerator pedal depression angle sensor) is provided on the accelerator pedal, and outputs a detection signal according to the depression amount of the accelerator pedal by the driver to the control device 70.

● [Examples of switching supercharging control and dropping of supercharging pressure and torque during the transition transition period (Figs. 2 and 3)]
In FIG. 2, the supercharging control is changed from 1 turbo (supercharging only with the first supercharger 31 (see FIG. 1)) to 2 turbos (first supercharger 31 and second supercharger 32 (see FIG. 1)). An example of switching to supercharging on both sides is shown. In the example of FIG. 2, supercharging control is performed with 1 turbo until time Ta, a switching condition for switching from 1 turbo to 2 turbo is satisfied at time Ta, and supercharging control is performed with 2 turbos after time Tb. An example is shown. The times Ta to Tb are the times during switching when switching from 1 turbo to 2 turbo.

Until the time Ta, the control device 70 determines that supercharging control is performed with one turbo. In this case, the control device 70 controls the intake bypass valve 61 to the closed state, the intake switching valve 62 to the closed state, and the exhaust switching valve 63 to the closed state. In this case, since the exhaust does not flow into the turbine 32B of the second supercharger 32, the second supercharger 32 does not supercharge, and only the first supercharger 31 supercharges (FIG. 1, FIG. 1, (See Fig. 2).

At time Ta, the control device 70 determines that the switching condition for switching from the supercharging control of 1 turbo to the supercharging control of 2 turbos is satisfied. In this case, the control device 70 temporarily connects the second supercharger 32 and the first supercharger 31 in series to supercharge, as described below, in order to suppress the drop in supercharging. In this case, the control device 70 controls the intake bypass valve 61 to the open state, the intake switching valve 62 to the closed state, and the exhaust switching valve 63 to the open state. It should be noted that this state is maintained until the switching time elapses from the time Ta, and the second supercharger 32 and the first supercharger 31 are connected in series to supercharge (see FIGS. 1 and 2). ).

After the time Tb when the switching time elapses from the time Ta, the control device 70 determines that the supercharging control is performed by the two turbochargers. In this case, the control device 70 controls the intake bypass valve 61 in the closed state, controls the intake switching valve 62 in the open state, and controls the exhaust switching valve 63 in the open state. In this case, the control device 70 supercharges by using the first supercharger 31 and the second supercharger 32 in parallel (see FIGS. 1 and 2).

As shown in FIG. 2, the transition state time (corresponding to the switching transition period) from the time Ta when switching from 1 turbo to 2 turbo is started, from the time Tb when switching to 2 turbo to the time Tc when a further time elapses. ), Since the rotation speed of the turbine of the second supercharger has not risen sufficiently, a drop in the supercharging pressure occurs. Then, as the supercharging pressure drops, the output torque of the internal combustion engine 10 also drops. The user can hardly feel the drop in the supercharging pressure, but the drop in the output torque is accompanied by the shock of the vehicle equipped with the internal combustion engine, so the user can feel it. As described below, in the processing of the control device described in the present embodiment, this drop in output torque is suppressed to the extent that the user cannot experience it.

The amount of drop in the output torque shown in FIG. 2 is hereinafter referred to as the total loss torque ΔTQ. The inventor repeated various experiments and simulations to analyze the factors of the total loss torque ΔTQ. Then, as shown in FIG. 3, the inventor has found that the total loss torque ΔTQ is the sum of the cooling loss torque, the exhaust loss torque, and the pump loss torque. As can be seen from FIG. 3, the cooling loss torque is dominant in the total loss torque ΔTQ (the ratio is very large).

The cooling loss torque is the torque lost due to the amount of heat (heat loss) taken from the cylinder or piston by colliding with the cylinder or piston before the fuel injected into the cylinder atomizes as the boost pressure drops. Is. For this cooling loss torque, a method for calculating the cooling loss torque according to the coolant temperature and boost pressure can be derived by acquiring and analyzing various experimental data with respect to the actual coolant temperature and boost pressure of the internal combustion engine. Can be done. That is, the increased cooling loss torque can be obtained by subtracting the cooling loss torque before switching the supercharging control from the cooling loss torque in the transition state time. The control device can estimate the heat loss torque lost in the heat loss of the piston and cylinder of the internal combustion engine based on the increase in heat loss caused by the drop in supercharging, as will be described later.

Exhaust loss torque is the torque that "gains" due to the decrease in exhaust pressure that accompanies the drop in supercharging pressure. The exhaust pressure loss is the hardware from the oxidation catalyst 51 shown in FIG. 1 to the exhaust gas to the atmosphere, and the pressure loss characteristic is almost determined. The exhaust pressure in the exhaust manifold 12A1 of the internal combustion engine 10 is the atmospheric pressure detected by the atmospheric pressure detecting means 22D, the above pressure loss characteristics, the differential pressure detected by the differential pressure detecting means 22C, and the variable nozzle 31C. It can be obtained from the opening degree. Then, the exhaust loss torque can be obtained from the exhaust pressure in the exhaust manifold 12A1 of the internal combustion engine 10. That is, the "reduced" exhaust loss torque can be obtained by subtracting the exhaust loss torque before switching the supercharging control from the exhaust loss torque in the transition state time. The control device can estimate the exhaust loss torque gained based on the reduction in the exhaust loss due to the drop in supercharging in the exhaust loss based on the exhaust flow rate from the cylinder of the internal combustion engine, as will be described later.

The pump loss torque is the torque determined by the intake side pressure, the exhaust side pressure, and the area of the upper surface of the piston when the piston operates as a pump that sucks intake air from the intake manifold and pumps exhaust air to the exhaust manifold. is there. When the supercharging pressure drops, the force for suction increases, so when the supercharging pressure drops, the pump loss increases. That is, the increased pump loss torque can be obtained by subtracting the pump loss torque before switching the supercharging control from the pump loss torque in the transition state time. The control device can estimate the pump loss torque that is lost based on the increase in the pump loss due to the drop in supercharging in the pump loss based on the pump operation of the intake and exhaust by the piston of the internal combustion engine, as described later. ..

● [Processing procedure of control device 70 (FIGS. 4 to 8)]
Next, an example of the processing procedure of the control device 70 (control means 71) will be described with reference to the flowcharts shown in FIGS. 4 to 8. The process shown in FIG. 4 is started, for example, at a predetermined time interval (for example, an interval of several [ms] to several tens [ms]), and when started, the control device 70 (control means 71) proceeds to step S010. To proceed.

In step S010, the control device 70 acquires and stores physical quantities based on the detection signals from various detection means as input signal processing, and proceeds to the process in step S020. For example, the current supercharging pressure, coolant temperature, amount of fuel to be injected, injection time width, fuel pressure, internal combustion engine rotation speed, intake flow rate, exhaust pressure, exhaust temperature, opening of variable nozzle of the first supercharger. , DPF differential pressure, atmospheric pressure, etc., this time supercharging pressure, this time coolant temperature, this time fuel amount, this time injection time width, this time fuel pressure, this time rotation speed, this time intake flow rate, this time exhaust pressure, this time exhaust It is stored as temperature, this time nozzle opening, this time differential pressure, this time atmospheric pressure, etc. The physical quantity to be stored is not limited to these.

In step S020, the control device 70 executes [SB000: supercharging control switching process] shown in FIG. 5, and proceeds to step S025. When the control device 70 executes [SB000: supercharging control switching process] shown in FIG. 5, the control device 70 proceeds to step SB010 shown in FIG.

[SB000: Supercharging control switching process]
In step SB010 shown in FIG. 5, the control device 70 determines whether or not it is currently in 1 turbocharging control (during single supercharging control in which only the first supercharger supercharges), and 1 turbocharger is in progress. If the supply control is in progress (Yes), the process proceeds to step SB020, and if the turbocharging control is not in progress (No), the process proceeds to step SB110. The process of SB000 shown in FIG. 5 is an existing process, from 1 turbocharging control (single supercharging control supercharging only with the first supercharger) to 2 turbocharging control (first supercharger). An example of the process of switching to (twin supercharging control in which both the turbocharger and the second turbocharger are supercharged) is shown. For details of step SB110, which is a process of switching from 2-turbocharging control to 1-turbocharging control, The description is omitted.

When the process proceeds to step SB020, the control device 70 determines whether or not the switching condition from 1 turbocharging control to 2 turbocharging control is satisfied based on the operating state of the internal combustion engine, and determines whether or not the switching condition is satisfied. If is satisfied (Yes), the process proceeds to step SB030, and if the switching condition is not satisfied (No), the process proceeds to step SB060A.

When the process proceeds to step SB030, the control device 70 determines whether or not the switching timer (see FIG. 2) is running, and if it is running (Yes), the process proceeds to step SB050 and starts. If not, the process proceeds to step SB040.

When the process proceeds to step SB040, the control device 70 turns on the switching start flag, activates the switching timer, and proceeds to step SB050.

When the process proceeds to step SB050, the control device 70 determines whether or not the switching timer is less than the switching time (see FIG. 2), and if it is less than the switching time (Yes), the process proceeds to step SB060B. If the switching time is longer than or equal to (No), the process proceeds to step SB060C. The value of the switching time is set to an appropriate value by various experiments using an actual vehicle.

When the process proceeds to step SB060A, it is a case where the 1 turbocharging control is maintained (continued), and a case where the supercharging is performed only by the first supercharger. The control device 70 controls the intake bypass valve 61 to the closed state, controls the intake switching valve 62 to the closed state, controls the exhaust switching valve 63 to the closed state (see FIG. 2), and proceeds to step SB070A.

In step SB070A, the control device 70 stops and initializes the switching timer, ends the process shown in FIG. 5, and proceeds to step S025 shown in FIG.

When the process proceeds to step SB060B, it means that the 1-turbo supercharging control is being switched to the 2-turbo supercharging control, and the second supercharger and the first supercharger are connected in series to supercharge. It is a case to do. The control device 70 controls the intake bypass valve 61 in the open state, controls the intake switching valve 62 in the closed state, controls the exhaust switching valve 63 in the open state (see FIG. 2), and ends the process shown in FIG. Then, the process proceeds to step S025 shown in FIG.

When the process is advanced to step SB060C, it is the case where the two turbocharger control is maintained (continued), and the case where both the first turbocharger and the second turbocharger are supercharged in parallel. is there. The control device 70 controls the intake bypass valve 61 in the closed state, controls the intake switching valve 62 in the open state, controls the exhaust switching valve 63 in the open state (see FIG. 2), and proceeds to step SB070C.

In step SB070C, the control device 70 stops and initializes the switching timer, ends the process shown in FIG. 5, and proceeds to step S025 shown in FIG.

The control means 71 that executes the process of steps SB010 to SB070C described above is a supercharging switching means 71A (see FIG. 1) that switches the number of superchargers used for supercharging control according to the operating state of the internal combustion engine. It is equivalent.

In step S025 shown in FIG. 4, the control device 70 determines whether or not the switching start flag (which is turned ON in step SB040 of FIG. 5) is ON, and when the switching start flag is ON (Yes). ) Proceeds to step S030, and if the switching start flag is not ON (No), the process proceeds to step S040.

When the process proceeds to step S030, the control device 70 determines that the current timing is the time Ta shown in FIG. 2, stores the boost pressure this time in the boost pressure before switching, and sets the coolant temperature before switching. The coolant temperature is stored this time, the fuel amount is stored in the fuel amount before switching, the injection time width is stored in the injection time width before switching, the fuel pressure is stored in the fuel pressure before switching, and the rotation speed before switching is used. The number of rotations is memorized this time, the intake flow flow is memorized in the intake flow before switching, the exhaust pressure is memorized in the exhaust pressure before switching, the exhaust temperature is memorized in the exhaust temperature before switching, and the nozzle opening before switching is memorized this time. The nozzle opening degree is memorized, the differential pressure is memorized in the differential pressure before switching, the atmospheric pressure is memorized in the atmospheric pressure before switching, and the process proceeds to step S035. The various physical quantities stored in step S030 are used when estimating various loss torques in steps S050 to S065. The physical quantity stored as "before switching" is not limited to these.

In step S035, the control device 70 activates the switching transient timer (see FIG. 2) to proceed to step S040.

When the process proceeds to step S040, the control device 70 determines whether or not the switching transient timer is running, and if the switching transient timer is running (Yes), the process proceeds to step S045 to switch. If the transient timer is not running (No), the process proceeds to step S070.

When the step S045 process is advanced, the control device 70 determines whether or not the switching transient timer is equal to or less than the transition state time (switching transition period) (see FIG. 2), and if it is equal to or less than the transition state time (Yes). Proceeds to step S050, and if the transition state time has been exceeded (No), proceeds to step S070. The value of the transition state time (switching transition period) is set to an appropriate value by various experiments using an actual vehicle, and as shown in FIG. 2, during and after the switching, in a predetermined time. This is the time (duration) during which the boost pressure and output torque drop occur. For example, the transition state time (switching transition period) is about 1 to 2 [sec].

When the process proceeds to step S070, the control device 70 stops and initializes the switching transient timer, initializes the injection start timing correction amount, the fuel pressure correction amount, and the fuel correction amount, and proceeds to the process to step S165.

When the process proceeds to step S050, the control device 70 estimates the cooling loss torque (see FIG. 3) and proceeds to step S055. For example, the control device 70 can estimate the cooling loss torque from map values and the like according to the coolant temperature and boost pressure obtained in various experiments and various simulations using an actual vehicle. The control device 70 estimates the cooling loss torque (before switching) using the map, the supercharging pressure before switching, the coolant temperature before switching, etc., and uses the map, the supercharging pressure this time, the coolant temperature, etc. This time) Estimate the cooling loss torque. Then, the control device 70 can estimate the increased cooling loss torque with respect to the one before switching by subtracting the (before switching) cooling loss torque from the (this time) cooling loss torque. The method for estimating the increased cooling loss torque is not limited to the above method.

In step S055, the control device 70 estimates the exhaust loss torque (see FIG. 3) and proceeds to step S060. For example, the control device 70 has an exhaust loss torque based on a map value corresponding to the exhaust flow rate and the exhaust pressure (pressure in the exhaust manifold) and the differential pressure of the DPF obtained in various experiments and various simulations using an actual vehicle. Can be estimated. The control device 70 exhausts (before switching) using the map, the exhaust flow rate before switching (calculated from the intake flow rate before switching and the exhaust temperature before switching), the exhaust pressure before switching, the differential pressure before switching, the nozzle opening before switching, and the like. The loss torque is estimated, and the (this time) exhaust loss torque is estimated using the map, the current exhaust flow rate (calculated from the current intake flow rate and the current exhaust temperature), the current exhaust pressure, the current differential pressure, the current nozzle opening, and the like. The pre-switching exhaust pressure (exhaust manifold internal pressure) can be estimated from the pre-switching exhaust pressure (turbine downstream pressure), the pre-switching nozzle opening, and the like. Then, the control device 70 can estimate the exhaust loss torque reduced with respect to that before the switching by subtracting the exhaust loss torque (this time) from the exhaust loss torque (before switching). The method for estimating the reduced exhaust loss torque is not limited to the above method.

In step S060, the control device 70 estimates the pump loss torque (see FIG. 3) and proceeds to step S065. For example, the control device 70 includes map values according to the supercharging pressure and the exhaust pressure (pressure in the exhaust manifold) obtained by various experiments and various simulations using an actual vehicle, and the supercharging pressure and the exhaust pressure. The pump loss can be estimated from the area of the upper surface of the piston. The control device 70 estimates the pump loss torque (before switching) by using the map, the pre-switching boost pressure and the pre-switching exhaust pressure, the pre-switching boost pressure, the pre-switching exhaust pressure, the area of the upper surface of the piston, and the like. The pump loss torque is estimated using the map, the boost pressure this time, the exhaust pressure this time, the boost pressure this time, the exhaust pressure this time, the area of the upper surface of the piston, and so on. The pre-switching exhaust pressure (exhaust manifold internal pressure) can be estimated from the pre-switching exhaust pressure (turbine downstream pressure), the pre-switching nozzle opening, and the like. Then, the control device 70 can estimate the pump loss torque increased with respect to that before the switching by subtracting the pump loss torque (before switching) from the pump loss torque (this time). The method for estimating the increased pump loss torque is not limited to the above method.

In step S065, the control device 70 estimates the total loss torque and proceeds to step S110. In this case, the control device 70 estimates (calculates) the total loss torque by "total loss torque = cooling loss torque-exhaust loss torque + pump loss torque (see FIG. 3)".

The control means 71 that executes the processes of steps S040 to S065 described above sets a target from a state in which a drop in supercharging occurs immediately after switching the number of superchargers using the supercharging switching means 71A (see FIG. 1). It corresponds to the total loss torque estimation means 71B (see FIG. 1) that estimates the total loss torque, which is the torque loss due to the drop in supercharging, in the switching transition period until the supercharging state is reached.

In step S110, the control device 70 calculates the first required torque based on the total loss torque and proceeds to step S115. For example, the control device 70 calculates the first required torque by subtracting a predetermined torque (for example, 10 [Nm]) from the total loss torque. The predetermined torque is a torque reduction amount that the user does not experience. Hereinafter, in steps S115 to S160B, the compensation torque for supplementing the first required torque is sequentially obtained. The compensating torque is obtained in three stages, and first, compensating is performed by the first compensating torque that advances (advances) the fuel injection start time. If the torque is insufficient with the first compensation torque, the second compensation torque that further increases the fuel pressure is added to compensate. If the torque is insufficient even with the first compensation torque and the second compensation torque, the third compensation torque that further increases the fuel amount is added to compensate.

The control means 71 that executes the process of step S110 corresponds to the first required torque calculating means 71C (see FIG. 1) that calculates the first required torque according to the estimated total loss torque in the switching transition period. ing.

In step S115, the control device 70 determines the first compensation torque with respect to the first required torque, and proceeds to the process in step S120. The first compensation torque is the torque obtained by advancing the fuel injection start time (advancing the angle), and since there is an upper limit for advancing the injection start time (advancing the angle), the obtained torque also has an upper limit. is there. For example, when the upper limit of the first compensation torque obtained from various experiments and various simulations using an actual vehicle is 30 [Nm], each of 10 [Nm], 20 [Nm], and 30 [Nm] is set. Prepare the obtained injection advance angle increase value map (three maps, a map for 10 [Nm], a map for 20 [Nm], and a map for 30 [Nm]). Each injection advance angle increase value map is, for example, a map in which an injection advance angle increase value is set according to the rotation speed of the internal combustion engine and the amount of fuel. For example, when the first required torque is 40 [Nm], the control device 70 determines the first compensation torque as the upper limit of 30 [Nm], and when the first required torque is 25 [Nm], the first compensation The torque is determined to be 25 [Nm]. The value of the first compensation torque is determined to be equal to or less than the value of the first required torque.

The control means 71 that executes the process of step S115 calculates the first compensation torque, which is the torque increased according to the fuel injection start timing that has been accelerated based on the injection start timing correction amount in the switching transition period. It corresponds to the first compensation torque calculation means 71F (see FIG. 1).

In step S120, the control device 70 calculates the injection start timing correction amount (injection advance angle increase value) according to the first compensation torque, and proceeds to the process in step S125. For example, when the first compensation torque is 30 [Nm], the control device 70 obtains the injection advance angle increase value from the map for 30 [Nm], the current rotation speed, and the current fuel amount, and stores it in the injection start timing correction amount. .. Further, for example, when the first compensation torque is 25 [Nm], the control device 70 includes a map for 20 [Nm], an injection advance angle increase value obtained from the current rotation speed and the current fuel amount, and a map for 30 [Nm]. And the injection advance angle increase value obtained from the current rotation speed and the fuel amount this time are interpolated to obtain the injection advance angle increase value for 25 [Nm] and stored in the injection start timing correction amount.

The control means 71 that executes the process of step S120 calculates the injection start time correction amount based on the calculated first required torque (first compensation torque based on) in the switching transition period. It corresponds to the quantity calculation means 71D (see FIG. 1).

In step S125, the control device 70 obtains the second required torque (≧ 0) obtained by subtracting the first compensation torque from the first required torque, and proceeds to the process in step S130. Since there is an upper limit to the first compensation torque, the torque that is insufficient for the first compensation torque with respect to the first required torque is the second required torque.

The control means 71 that executes the process of step S125 is the second required torque calculation means that calculates the second required torque, which is the torque that the first supplement torque is insufficient for the first required torque in the switching transition period. It corresponds to 71G (see FIG. 1).

In step S130, the control device 70 determines whether or not there is a second required torque (whether or not it is greater than zero), and if there is a second required torque (Yes), the process proceeds to step S135, and the second If there is no required torque (zero), the process proceeds to step S140B.

When the process proceeds to step S135, the control device 70 determines the second compensation torque with respect to the second required torque and proceeds to the process to step S140A. The second compensation torque is a torque obtained by increasing the fuel pressure and shortening the fuel injection time width, and since there is an upper limit for increasing the fuel pressure, the obtained torque also has an upper limit. For example, when the upper limit of the second compensation torque obtained from various experiments and various simulations using an actual vehicle is 30 [Nm], 10 [Nm], 20 [Nm], and 30 [Nm] are set respectively. Prepare the obtained fuel pressure increase value map (three maps, a map for 10 [Nm], a map for 20 [Nm], and a map for 30 [Nm]). Each fuel pressure increase value map is, for example, a map in which a fuel pressure increase value is set according to the rotation speed of the internal combustion engine and the fuel amount. For example, when the second required torque is 40 [Nm], the control device 70 determines the second compensation torque to be the upper limit of 30 [Nm], and when the second required torque is 25 [Nm], the second compensation is made. The torque is determined to be 25 [Nm]. The value of the second compensation torque is determined to be equal to or less than the value of the second required torque.

The control means 71 that executes the processes of steps S130 to S135 is a torque that increases according to the fuel pressure increased based on the fuel pressure correction amount when there is a second required torque in the switching transition period. It corresponds to the second compensation torque calculation means 71J (see FIG. 1) that calculates the two compensation torques.

In step S140A, the control device 70 calculates the fuel pressure correction amount (fuel pressure increase value) according to the second compensation torque, and proceeds to the process in step S145. For example, when the second compensation torque is 30 [Nm], the control device 70 obtains a fuel pressure increase value from the map for 30 [Nm], the current rotation speed, and the current fuel amount, and stores it in the fuel pressure correction amount. Further, for example, when the second compensation torque is 25 [Nm], the control device 70 includes a map for 20 [Nm], a fuel pressure increase value obtained from the current rotation speed and the current fuel amount, and a map for 30 [Nm]. The fuel pressure increase value for 25 [Nm] is obtained by interpolating between the current rotation speed and the fuel pressure increase value obtained from the fuel amount this time, and stored in the fuel pressure correction amount.

The control means 71 that executes the processes of steps S130 to S140A calculates the fuel pressure correction amount based on the second required torque when there is a second required torque in the switching transition period. Fuel pressure correction amount calculation It corresponds to means 71H (see FIG. 1).

In step S145, the control device 70 obtains a third required torque (≧ 0) obtained by subtracting the second compensating torque from the second required torque, and proceeds to step S150. Since there is an upper limit to the second compensation torque, the torque that is insufficient for the second compensation torque with respect to the second required torque is the third required torque.

In the switching transition period, the control means 71 that executes the process of step S145 obtains a third required torque, which is a torque that is insufficient for the second supplement torque with respect to the second required torque when there is a second required torque. It corresponds to the third required torque calculation means 71K (see FIG. 1) for calculation.

In step S150, the control device 70 determines whether or not there is a third required torque (whether or not it is greater than zero), and if there is a third required torque (Yes), the process proceeds to step S155, and the third If there is no required torque (zero), the process proceeds to step S160B.

When the process proceeds to step S155, the control device 70 determines the third compensation torque with respect to the third required torque and proceeds to the process to step S160A. The third compensation torque is the torque obtained by increasing the amount of fuel, and the upper limit value can sufficiently compensate the total loss torque. Therefore, the control device 70 determines the value of the third compensation torque to the value of the third required torque. For example, when the third required torque is 25 [Nm], the third compensation torque is determined to be 25 [Nm]. For example, the amount of fuel increased to obtain 10 [Nm], 20 [Nm], 30 [Nm], 40 [Nm], 50 [Nm], etc. from various experiments and various simulations using actual vehicles. Prepare a value map (five maps: a map for 10 [Nm], a map for 20 [Nm], a map for 30 [Nm], a map for 40 [Nm], and a map for 50 [Nm]). Each fuel amount increase value map is, for example, a map in which a fuel amount increase value is set according to the rotation speed of the internal combustion engine and the fuel amount.

In step S160A, the control device 70 calculates the fuel correction amount (fuel amount increase value) according to the third compensation torque, and proceeds to the process in step S165. For example, when the third compensation torque is 25 [Nm], the control device 70 has a map for 20 [Nm], a fuel amount increase value obtained from the current rotation speed and the fuel amount this time, a map for 30 [Nm], and this time. By interpolating between the number of revolutions and the fuel amount increase value obtained from the fuel amount this time, the fuel amount increase value for 25 [Nm] is obtained and stored in the fuel correction amount.

The control means 71 that executes the processes of steps S150 to S160A calculates the fuel correction amount based on the third required torque when there is a third required torque in the switching transition period. The fuel correction amount calculating means 71L. (See Fig. 1).

When the process proceeds to step S140B, the control device 70 initializes (sets to zero) the fuel pressure correction amount and proceeds to the process to step S160B.

When the process proceeds to step S160B, the control device 70 initializes (sets to zero) the fuel correction amount and proceeds to the process to step S165.

When the process proceeds to step S165, the control device 70 turns off the switching start flag and ends the process.

The processing that reflects each correction amount of the injection start timing correction amount obtained as the first compensation torque, the fuel pressure correction amount obtained as the second compensation torque, and the fuel correction amount obtained as the third compensation torque is shown in the figure. This will be described with reference to the flowchart shown in 6.

● [Processing procedure that reflects the injection start time correction amount, fuel pressure correction amount, and fuel injection amount (Figs. 6 to 8)]
[Fuel injection timing processing (Fig. 6)]
The injection start timing correction amount is reflected in the existing [fuel injection timing processing]. As shown in FIG. 6, steps SC010, SC020A, and SC020B are newly added to the existing step SC030 in [Fuel injection timing processing]. When executing [fuel injection timing processing], the control device 70 advances the processing to step SC010.

In step SC010, the control device 70 determines whether or not there is an injection start time correction amount (zero or not), and if there is an injection start time correction amount (Yes), the process proceeds to step SC020A and the injection is started. If there is no timing correction amount (No), the process proceeds to step SC020B.

When the process proceeds to step SC020A, the control device 70 stores the value obtained by adding the injection start time correction amount to the normal injection timing at the target injection start time and proceeds to the process to step SC030. The normal injection timing is a value calculated by the control device 70 by an existing process (not shown) according to the operating state of the internal combustion engine, and is a predetermined timing in which the piston of the internal combustion engine is near the position of the compression top dead center. Is.

When the process proceeds to step SC020B, the control device 70 stores the value of the normal injection timing at the target injection start time and proceeds to the process to step SC030.

When the process (existing process) is advanced to step SC030, the control device 70 controls the injection start timings from the injectors 43A to 43H so as to start the fuel injection at the target injection start timing, and ends the process.

The control means 71 that executes the process of steps SC010 to SC030 described above sets the fuel injection start time earlier than the normal injection timing based on the calculated injection start time correction amount in the switching transition period. It corresponds to 71E (see FIG. 1).

[Fuel pressure treatment (Fig. 7)]
The fuel pressure correction amount is reflected in the existing [fuel pressure processing]. As shown in FIG. 7, in [Fuel pressure processing], steps SD010, SD020A, and SD020B are newly added to the existing step SD030. When executing [fuel pressure processing], the control device 70 advances the processing to step SD010.

In step SD010, the control device 70 determines whether or not there is a fuel pressure correction amount (whether or not it is zero), and if there is a fuel pressure correction amount (Yes), the process proceeds to step SD020A, and the fuel pressure correction amount If there is no (No), the process proceeds to step SD020B.

When the process proceeds to step SD020A, the control device 70 stores the value obtained by adding the fuel pressure correction amount to the normal fuel pressure in the target fuel pressure and proceeds to the process to step SD030. The normal fuel pressure is a value calculated by the control device 70 by an existing process (not shown) according to the operating state of the internal combustion engine.

When the process proceeds to step SD020B, the control device 70 stores the value of the normal fuel pressure in the target fuel pressure and proceeds to the process to step SD030.

When the process (existing process) is advanced to step SD030, the control device 70 controls the fuel pressure adjusting pump 41 so as to reach the target fuel pressure, and ends the process.

The control means 71 that executes the process of the above steps SD010 to SD030 raises the fuel pressure (higher than the normal fuel pressure Fpn) based on the calculated fuel pressure correction amount in the switching transition period, and is a fuel pressure changing means. It corresponds to 71I (see FIG. 1).

[Fuel injection processing (Fig. 8)]
The fuel correction amount is reflected in the existing [fuel injection process]. As shown in FIG. 8, in [fuel injection processing], steps SE010, SE020A, and SE020B are newly added to the existing step SE030. When executing the [fuel injection process], the control device 70 proceeds to step SE010.

In step SE010, the control device 70 determines whether or not there is a fuel correction amount (whether or not it is zero), and if there is a fuel correction amount (Yes), the process proceeds to step SE020A, and if there is no fuel correction amount. (No) proceeds to step SE020B.

When the process proceeds to step SE020A, the control device 70 stores the value obtained by adding the fuel correction amount to the normal fuel amount in the target fuel amount and proceeds to the process to step SE030. The normal fuel amount is a value calculated by the control device 70 by an existing process (not shown) according to the operating state of the internal combustion engine.

When the process proceeds to step SE020B, the control device 70 stores the value of the normal fuel amount in the target fuel amount and proceeds to the process to step SE030.

When the process (existing process) is advanced to step SE030, the control device 70 acquires the current fuel pressure and converts the target fuel amount into the injection time width according to the current fuel pressure. Then, the control device 70 controls the injectors 43A to 43H so that the injection time width from the target injection start time becomes the converted injection time width, and ends the process.

The control means 71 that executes the processes of steps SE010 to SE030 increases the amount of fuel injected into the cylinder based on the calculated fuel correction amount (increases from the normal fuel amount Qmn) in the switching transition period. It corresponds to the fuel amount changing means 71M (see FIG. 1).

Hereinafter, the fuel injection start time is advanced (advanced) to increase the torque [first compensation], the fuel pressure is increased to increase the torque [second compensation], and the fuel amount is increased to increase the torque. Fuel injection timing, fuel injection time width, pressure in the combustion process in the cylinder in [3rd compensation], which is the state before performing these 1st compensation, 2nd compensation, and 3rd compensation [before correction] The state will be described.

● [Example of state before correction (Fig. 9)]
9 to 12 show the pressure generated by the combustion process in the cylinder and the fuel injection pulse (injector drive signal) when the horizontal axis is the piston position (crank angle position) with respect to the target cylinder. , Fuel pressure, and fuel amount are shown.

FIG. 9 shows a state before executing the above [first compensation], [second compensation], and [third compensation], and the fuel injection start timing is the normal injection timing (advance angle amount θsn, which is the conventional state. An example is shown in the case where the advance angle amount), the fuel pressure is the normal fuel pressure Fpn (conventional fuel pressure), and the fuel amount is the normal fuel amount Qmn (conventional fuel amount).

The fuel injection pulse is a position where a small amount of fuel that promotes combustion is executed at pre-injection P1, P2, etc. from slightly before the compression top dead center of the target cylinder, and then the advance angle θsn is before the compression top dead center. The main injection M1 is executed from (normal injection timing). The number, timing, pulse width, etc. of the pre-injections P1 and P2 are not limited to these.

When fuel is injected into the cylinder by the main injection M1, the injected fuel burns and an expansion pressure Pn is generated. The peak pressure Pp, which is the peak of the expansion pressure Pn, is set with an advance angle θsn (normal injection timing) at the injection start timing of the main injection M1 so that the retard angle amount θpn is set from the compression top dead center.

● [Example of the first compensation state (Fig. 10)]
FIG. 10 shows a state in which the above [first compensation] is being executed, and the fuel injection start timing of the main injection M1 is set to the advance angle amount θsn (normal injection) with respect to the [before correction] shown in FIG. An example of a state in which the advance angle amount (θsn + Δθs) is increased from the timing) is shown (Δθs is the injection start timing correction amount). In the example shown in FIG. 10, the fuel injection start timing of the pre-injection P1 and P2 is also advanced as the fuel injection start timing of the main injection M1 is advanced.

Combustion also becomes faster as the fuel injection start timing of the main injection M1 is earlier, and the position of the expansion pressure Pn1 and the position of the peak pressure Pp1 are higher than the positions of the expansion pressure Pn and the peak pressure Pp shown in FIG. Move to the advance side. That is, since the peak pressure Pp1 is generated at a position where the position of the piston is closer to the compression top dead center, the torque can be increased without increasing the amount of fuel. The control device can adjust the generated torque by adjusting the fuel injection start timing back and forth with respect to the normal injection timing (advance angle amount θsn). Since the position of the peak pressure Pp1 must not be on the advance angle side of the compression top dead center (on the left side of the position of the compression top dead center in FIG. 10), there is a limit to the injection start timing correction amount Δθs.

● [Example of the second compensation state (Fig. 11)]
FIG. 11 shows a state in which the above [second compensation] is being executed, and further, from the state of [first compensation] shown in FIG. 10, the fuel pressure is further increased from the normal fuel pressure Fpn to the fuel pressure (Fpn + ΔFp). ) Is shown as an example (ΔFp is the fuel pressure correction amount). Since the fuel pressure is increased, the injection angle width Tn of the main injection M1 is changed to the injection angle width Tn2 and the injection angle width is shortened even if the fuel amount (normal fuel amount Qmn) has not changed. That is, the injection time width converted from the injection angle width is also shortened.

By shortening the injection angle width (that is, the injection time width) of the main injection M1, the piston can finish injecting fuel at a position closer to the position of the compression top dead center. Therefore, the expansion pressure Pn2 can be raised from substantially the same timing as the rising timing of the expansion pressure Pn1, and the angular width Wn2 of the expansion pressure Pn2 can be made narrower than the angular width Wn1 of the expansion pressure Pn1. That is, since the expansion pressure Pn2 can be generated at a position closer to the compression top dead center by the piston, the torque can be increased without increasing the fuel amount. The control device can adjust the generated torque by adjusting the fuel pressure to be higher or lower than the normal fuel pressure Fpn to adjust the fuel injection time width. Since the upper limit of the fuel pressure is determined by various factors, the fuel pressure correction amount ΔFp is also limited.

● [Example of the third compensation state (Fig. 12)]
FIG. 12 shows a state in which the above [third replenishment] is being executed, and further, from the state of [second replenishment] shown in FIG. 11, the fuel amount is further changed from the normal fuel amount Qmn to the fuel amount (Qmn + ΔQm). ) Is shown (ΔQm is the fuel correction amount). Since the amount of fuel is increased, the pulse width of the fuel injection pulse of the main injection M1 increases from the injection angle width Tn2 to the injection angle width Tn2 + ΔTn.

Since the injection angle width of the main injection M1 is lengthened to increase the amount of fuel, the area of the expansion pressure Pn3 is increased, and the torque can be increased. The control device can adjust the generated torque by adjusting the amount of fuel injected into the cylinder so as to increase or decrease the amount with respect to the normal fuel amount Qmn. Further, since the torque that is insufficient even in the first compensation and the second compensation is compensated by the third compensation, the amount of fuel to be increased (fuel correction amount ΔQm) is not so large, and the fuel correction amount ΔQm reaches the limit (upper limit). That is unlikely.

● [Example of how the drop in output torque is compensated by the first compensation, the second compensation, and the third compensation (Fig. 13)]
FIG. 13 shows how the drop in output torque shown in FIG. 2 is compensated by the first compensation, the second compensation, and the third compensation by the processing of the control device described above. TQ1 in the output torque of FIG. 13 indicates the upper limit compensation torque that can be compensated by the first compensation, and TQ2 indicates the upper limit compensation torque that can be compensated by the second compensation.

At the time T1 when the output torque starts to drop after the time Ta and the torque drop amount is TQ1 or less, the torque is compensated only by the injection start time correction amount (first compensation).

In the time T2 following the time T1, the torque drop amount is TQ1 or more and TQ1 + TQ2 or less, and the torque is compensated by the injection start time correction amount (first compensation) + fuel pressure correction amount (second compensation). In this case, the portion exceeding TQ1 is compensated by the first compensation, and the portion exceeding TQ1 is compensated by the second compensation.

At the time T3 following the time T2, the torque drop amount exceeds TQ1 + TQ2, so the torque is calculated by the injection start time correction amount (first compensation) + fuel pressure correction amount (second compensation) + fuel correction amount (third compensation). It will be compensated. In this case, the TQ1 portion is compensated by the first compensation, the TQ2 portion is supplemented by the second compensation, and the portion exceeding TQ1 + TQ2 is supplemented by the third compensation.

In the time T4 following the time T3, the torque drop amount is TQ1 or more and TQ1 + TQ2 or less, and the torque is compensated by the injection start time correction amount (first compensation) + fuel pressure correction amount (second compensation). In this case, the portion exceeding TQ1 is compensated by the first compensation, and the portion exceeding TQ1 is compensated by the second compensation.

At the time T5 following the time T4, the torque drop amount is TQ1 or less, and the torque is compensated only by the injection start timing correction amount (first compensation).

The control device for an internal combustion engine of the present invention is not limited to the configuration, structure, processing procedure, operation, etc. described in the present embodiment, and various changes, additions, and deletions can be made without changing the gist of the present invention. is there. Further, the internal combustion engine system is not limited to the one shown in the example of FIG. 1, and can be applied to various internal combustion engine systems.

In the description of the present embodiment, an internal combustion engine system having two superchargers, a first supercharger and a second supercharger, has been described as an example, but an internal combustion engine having three or more superchargers has been described. However, it is possible to apply the present invention that suppresses a drop in torque during the switching transition period immediately after switching the number of turbochargers. Further, in the description of the present embodiment, an example of a configuration in which the first supercharger and the second supercharger are supercharged in parallel (a configuration in which supercharging can be performed in series) has been described. Regardless of whether the turbochargers are supercharged in parallel or in series, this book suppresses the drop in torque during the switching transition period immediately after switching the number of turbochargers. It is possible to apply the invention. Further, in the description of the present embodiment, an example in which a plurality of turbochargers are turbochargers has been described, but a plurality of turbochargers may be superchargers, and a plurality of turbochargers may be turbochargers and superchargers. It may be a charger, and it is possible to apply the present invention that suppresses a drop in torque during the switching transition period immediately after switching the number of turbochargers.

In the description of the present embodiment, the total loss torque is obtained based on the cooling loss torque, the exhaust loss torque, and the pump loss torque. However, since the cooling loss torque is dominant (the ratio is large), it is referred to as the cooling loss torque. It may be calculated based on the exhaust loss torque, or the cooling loss torque and the pump loss torque, or the cooling loss torque.

In the description of the present embodiment, an example of performing the first compensation for earliering the injection start time, the second compensation for increasing the fuel pressure, and the third compensation for increasing the fuel amount has been described, but only the first compensation or Only the first compensation and the second compensation may be carried out.

Further, the numerical values used in the description of the present embodiment are examples, and are not limited to these numerical values. Further, the above (≧), the following (≦), the larger (>), the less than (<), etc. may or may not include the equal sign.

10 Internal combustion engine 11A, 11B1, 11B2, 11C1, 11C2, 11D Intake pipe 11CB Intake bypass pipe 11E Intake manifold 12A1, 12A2 Exhaust manifold 12B1, 12B2, 12C1, 12C2 Exhaust pipe 12BB Exhaust bypass pipe 21A Intake flow detection means Detection means 22B Exhaust pressure detection means 22C Differential pressure detection means 22D Atmospheric pressure detection means 24 Coolant temperature detection means 25 Rotation detection means 26 Exhaust temperature detection means 27 Accelerator pedal depression amount detection means 31 First supercharger 31A, 32A Compressor 31B, 32B Turbine 31C, 32C Variable nozzle 31D, 32D Nozzle drive means 31E, 32E Nozzle opening detection means 32 Second turbocharger 41 Fuel pressure adjustment pump 51 Oxidation catalyst 52 DPF
53 Urea SCR
61 Intake bypass valve 62 Intake switching valve 63 Exhaust switching valve 70 Control device 71 Control means 71A Supercharging switching means 71B Total loss torque estimation means 71C First required torque calculation means 71D Injection start time correction amount calculation means 71E Injection start time changing means 71F 1st compensation torque calculation means 71G 2nd required torque calculation means 71H Fuel pressure correction amount calculation means 71I Fuel pressure change means 71J 2nd compensation torque calculation means 71K 3rd required torque calculation means 71L Fuel correction amount calculation means 71M Fuel amount change Means 73 Storage means Δθs Injection start timing correction amount ΔFp Fuel pressure correction amount ΔQm Fuel correction amount

Claims (6)

In an internal combustion engine control device that detects the operating state of an internal combustion engine having a plurality of turbochargers and controls the amount of fuel injected into the cylinder of the internal combustion engine based on the detected operating state.
The control device is
The generated torque can be adjusted by starting fuel injection at the normal injection timing, which is a predetermined timing when the piston of the internal combustion engine is near the position of the compression top dead center, and adjusting the amount of fuel injected into the cylinder. At the same time, the generated torque can be further adjusted by adjusting the fuel injection start timing before and after the normal injection timing.
A supercharging switching means that switches the number of superchargers used for supercharging control according to the operating state of the internal combustion engine.
Torque due to the drop in supercharging during the switching transition period from the state in which the drop in turbocharging occurs immediately after switching the number of turbochargers using the supercharging switching means to the time when the target supercharging state is reached. Total loss torque estimation means that estimates the total loss torque, which is the loss amount of
In the switching transition period, the first required torque calculating means for calculating the first required torque according to the estimated total loss torque, and
In the switching transition period, the injection start timing correction amount calculating means for calculating the injection start timing correction amount based on the calculated first required torque, and the injection start timing correction amount calculating means.
In the switching transition period, the injection start time changing means for making the fuel injection start time earlier than the normal injection timing based on the calculated injection start time correction amount, and
Have,
Control device for internal combustion engine. The control device for an internal combustion engine according to claim 1.
The total loss torque estimation means in the control device is
In the switching transition period
A cooling loss torque, which is a torque lost based on an increase in the heat loss due to a drop in supercharging in the heat loss of the piston and the cylinder of the internal combustion engine, is estimated.
The total loss torque is estimated based on the estimated cooling loss torque.
Control device for internal combustion engine. The control device for an internal combustion engine according to claim 2.
The total loss torque estimation means in the control device is
In the switching transition period
Further, the exhaust loss torque, which is the torque gained based on the reduction in the exhaust loss due to the drop in supercharging in the exhaust loss based on the exhaust flow rate from the cylinder of the internal combustion engine, is estimated.
The total loss torque is estimated based on the estimated cooling loss torque and the exhaust loss torque.
Control device for internal combustion engine. The control device for an internal combustion engine according to claim 3.
The total loss torque estimation means in the control device is
In the switching transition period
Further, the pump loss torque, which is the torque lost based on the increase in the pump loss due to the drop in supercharging in the pump loss based on the pump operation of the intake and exhaust by the piston of the internal combustion engine, is estimated.
The total loss torque is estimated based on the estimated cooling loss torque, the exhaust loss torque, and the pump loss torque.
Control device for internal combustion engine. The control device for an internal combustion engine according to any one of claims 1 to 4.
The control device is
The generated torque can be further adjusted by adjusting the fuel pressure, which is the pressure of the fuel injected into the cylinder of the internal combustion engine, to adjust the fuel injection time width.
In the switching transition period, the first compensation torque calculating means for calculating the first compensation torque, which is the torque increased according to the fuel injection start timing earlier based on the injection start timing correction amount,
In the switching transition period, the second required torque calculating means for calculating the second required torque, which is a torque insufficient for the first supplement torque with respect to the first required torque,
A fuel pressure correction amount calculating means that calculates a fuel pressure correction amount based on the second required torque when there is the second required torque in the switching transition period.
A fuel pressure changing means for increasing the fuel pressure based on the calculated fuel pressure correction amount during the switching transition period.
Have,
Control device for internal combustion engine. The control device for an internal combustion engine according to claim 5.
The control device is
A second compensation torque calculation means that calculates a second compensation torque, which is a torque increased according to a fuel pressure increased based on the fuel pressure correction amount, when there is the second required torque in the switching transition period. When,
With the third required torque calculation means, which calculates the third required torque, which is the torque insufficient for the second supplement torque, with respect to the second required torque when the second required torque is present in the switching transition period. ,
A fuel correction amount calculating means that calculates a fuel correction amount based on the third required torque when there is the third required torque in the switching transition period.
A fuel amount changing means for increasing the amount of fuel injected into the cylinder based on the calculated fuel correction amount during the switching transition period.
Have,
Control device for internal combustion engine.

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