JP7107254B2 - Control device for internal combustion engine - Google Patents

Description

The present invention relates to an internal combustion engine control device for controlling an internal combustion engine system having a plurality of superchargers.

2. Description of the Related Art In recent years, some internal combustion engines mounted on vehicles, construction machines, etc. are equipped with superchargers (so-called turbochargers) that supercharge using the energy of exhaust gas in order to obtain greater output. Furthermore, some internal combustion engines are equipped with two or more (multiple) superchargers. For example, in an internal combustion engine equipped with two turbochargers, a first turbocharger and a second turbocharger, the first turbocharger and the second turbocharger arranged in series and the first turbocharger There is one in which the feeder and the second supercharger are arranged in parallel.

An internal combustion engine with two superchargers arranged in series or in parallel can obtain improved response and torque from a low rotation range compared to an internal combustion engine with only one large supercharger. etc. However, in an internal combustion engine equipped with two turbochargers, depending on the operating conditions, there are cases where supercharging is performed by (almost) only one turbocharger and when supercharging is performed by two turbochargers. , must be switched. During the transitional period of switching from one supercharger 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. A decrease in torque is at a level that can be clearly felt by the user and gives the user a sense of discomfort, which is not preferable. Therefore, it is desired to suppress the amount of decrease in torque during a switching transition period in which the number of superchargers used for supercharging control is switched.

For example, Patent Literature 1 discloses an internal combustion engine system control device that controls an internal combustion engine in which a first turbocharger and a second turbocharger are arranged in series. In Patent Document 1, each cylinder is provided with an in-cylinder pressure sensor, the in-cylinder pressure of the cylinder in the exhaust process is acquired by the in-cylinder pressure sensor, and based on the acquired in-cylinder pressure, the first supercharger and the second turbocharger are controlled. Parameters related to fluctuations in exhaust pressure due to changes in the supply of exhaust gas to the supercharger are obtained. Then, based on the acquired parameters, the pump loss before switching the turbocharger (loss associated with the pumping operation of the intake and exhaust of the piston) and the pump loss during the transitional period of switching the turbocharger are calculated. I'm looking for a loss step. Then, based on the determined pump loss difference, a torque correction injection amount is calculated to increase the fuel injection amount (increase the torque), thereby suppressing torque fluctuations caused by the pump loss.

Patent Document 2 discloses a control device for an internal combustion engine that controls an internal combustion engine in which a first supercharger and a second supercharger are arranged in parallel. Note that the first turbocharger and the second turbocharger 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 switching transition period from a single turbo mode (supercharging with only one turbocharger) to a twin turbo mode (supercharging with two turbochargers). In the switching transition period, after the main injection that is the main part of the combustion process, a post-injection is performed to inject a small amount of fuel again into the combustion gas produced by the combustion process, raising the exhaust temperature and improving the expansion rate of the exhaust. there is As a result, in the supercharger switching transition period, the exhaust energy is increased (that is, the rise of the turbine rotation speed of the supercharger is accelerated), and the supercharging drop (torque drop) is suppressed.

Patent Document 3 discloses a supercharging system for an internal combustion engine 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 can also be driven by an electric motor. In the control device in Patent Document 3, the electric motor is operated during a switching transition period in which a state in which supercharging is performed by only the first turbocharger is switched to a state in which supercharging is performed by the first and second turbochargers. is used to instantaneously raise the rotation speed of the second supercharger, thereby suppressing a drop in supercharging (drop in torque).

JP 2010-190070 A JP 2010-151087 A JP 2010-048225 A

In the system described in Patent Literature 1, it is assumed that the drop in torque during the transitional period of switching of the supercharger is mostly due to pump loss torque. However, as a result of various experiments and simulations, it has been found that the cooling loss torque due to the increase in the amount of heat taken away by the cylinder and piston due to the drop in supercharging is greater than the pump loss torque. rice field. That is, even if the torque is increased to compensate for the pump loss torque, the torque is insufficient. Also, the amount of fuel injection (main injection amount) is increased in order to increase the torque, but this is not so desirable because it is accompanied by a decrease in fuel consumption. Furthermore, it is necessary to provide an in-cylinder pressure sensor for 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 Literature 2, post-injection is performed during the transitional period for switching the supercharger. However, during acceleration, it seems that the expansion ratio of the turbocharger is somehow within the constraints (restrictions to ensure durability and reliability, such as the upper limit of "turbine upstream pressure/turbine downstream pressure"). In such a situation, increasing the expansion ratio of the exhaust, even if temporarily, is not very desirable from the standpoint of durability and reliability. Post-injection to increase the expansion ratio of the exhaust increases the ratio of upstream pressure to downstream pressure of the turbocharger turbine, which may affect the durability and reliability of the turbine.

In the system described in Patent Document 3, since the electric motor is added to the second supercharger, the cost is increased and the size and weight are increased, which is not so preferable.

The present invention has been invented in view of the above points, and in an internal combustion engine system having a plurality of superchargers, it is possible to increase the durability of the supercharger without adding new equipment such as an electric motor. An object of the present invention is to provide a control device for an internal combustion engine capable of more appropriately suppressing a drop in torque that accompanies a switching transition period in which the number of superchargers used for supercharging control is switched without impairing reliability. do.

In order to solve the above-mentioned problems, a first invention of the present invention detects an operating state of an internal combustion engine having a plurality of superchargers, and injects fuel into a cylinder of the internal combustion engine based on the detected operating state. In a control device for an internal combustion engine that controls the amount of fuel, the control device starts fuel injection at normal injection timing, which is a predetermined timing when a piston of the internal combustion engine is near a position of compression top dead center, to start fuel injection to 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 forward or backward with respect to the normal injection timing. supercharging switching means for switching 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. total torque loss estimating means for estimating total loss torque, which is the amount of torque loss due to the drop in supercharging, during a switching transition period from the state in which the drop occurs until the target supercharging state is reached; a first request torque calculation means for calculating a first request torque corresponding to the estimated total loss torque during a switching transition period; and injection start timing correction based on the calculated first request torque during the switching transition period. injection start timing correction amount calculation means for calculating an injection start timing correction amount; and injection start timing change for making the fuel injection start timing earlier than the normal injection timing based on the calculated injection start timing correction amount during the switching transition period. and means for controlling an internal combustion engine.

Next, a second aspect of the present invention is the control device for an internal combustion engine according to the first aspect, wherein the total loss torque estimating means in the control device, during the switching transient period, estimating a cooling loss torque, which is a torque lost in the heat loss of the piston and the cylinder, based on the increase in the heat loss caused by the drop in supercharging, and based on the estimated cooling loss torque, the total torque loss; is a control device for an internal combustion engine.

Next, a third aspect of the present invention is the control device for an internal combustion engine according to the second aspect, wherein the total loss torque estimating means in the control device further includes, during the switching transition period, the internal combustion engine In the exhaust loss based on the exhaust flow rate from the cylinder of the engine, an exhaust loss torque, which is a torque gained based on the decrease in the exhaust loss caused by the decrease in supercharging, is estimated, and the estimated cooling loss torque and the A control device for an internal combustion engine, which estimates the total torque loss based on exhaust torque loss.

Next, a fourth aspect of the present invention is the control device for an internal combustion engine according to the third aspect, wherein the total loss torque estimating means in the control device further includes, during the switching transition period, the internal combustion engine Estimate pump loss torque, which is the torque lost based on the increase in pump loss caused by the drop in supercharging in the pump loss based on the intake and exhaust pump operations by the piston of the engine, and estimate the cooling loss A control device for an internal combustion engine, which estimates the total torque loss based on the torque, the exhaust torque loss, and the pump loss torque.

Next, a 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 comprises: The generated torque can be further adjusted by adjusting the fuel injection time width by adjusting the fuel pressure, which is the pressure of the fuel to be injected, and the injection start timing correction amount is advanced during the switching transition period. a first supplementary torque calculation means for calculating a first supplementary torque that is a torque increased according to the fuel injection start timing; and calculating a fuel pressure correction amount based on the second required torque when there is the second required torque during the switching transient period. and fuel pressure changing means for increasing the fuel pressure based on the calculated fuel pressure correction amount during the switching transient period.

Next, a sixth aspect of the present invention is a control device for an internal combustion engine according to the fifth aspect, wherein the control device controls the switching transition period when the second required torque is present. a second supplementary torque calculation means for calculating a second supplementary torque that is a torque increased according to the fuel pressure increased based on the fuel pressure correction amount; a third request torque calculation means for calculating a third request torque that is a torque insufficient for the second supplement torque with respect to the second request torque; and when there is the third request torque in the switching transient period a fuel correction amount calculating means for calculating a fuel correction amount based on the third required torque; and increasing an amount of fuel injected into the cylinder based on the calculated fuel correction amount during the switching transient period. , and fuel amount changing means.

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 is calculated according to the total loss torque, and based on the first required torque An injection start timing correction amount is calculated. Then, based on the injection start timing correction amount, the fuel injection start timing is made earlier than the normal injection timing. In other words, the fuel injection start timing is advanced without changing the fuel amount. In general, the injection start timing is adjusted so that the peak position of the expansion pressure due to the combustion of fuel injected into the cylinder is at a position where the piston has passed the compression top dead center and is slightly lowered for various reasons. ing. Therefore, by advancing the injection start timing in the switching transition period, the peak position of the expansion pressure is brought closer to the compression top dead center of the piston. 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 that accompanies the switching transition period in which the number of superchargers used for supercharging control is switched without adding a new device such as an electric motor. In addition, since the injection amount of fuel is not changed, the exhaust flow rate and exhaust pressure are almost unchanged. Therefore, it is possible to more appropriately suppress the drop in torque that accompanies the switching transition period in which the number of superchargers used for supercharging control is switched without impairing the durability and reliability of the superchargers.

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

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

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

When the fuel injection start timing is advanced to increase the generated torque, there is a limit to how much the injection start timing can be advanced, so there is a limit to the torque that can be increased (first supplementary torque). According to the fifth aspect of the present invention, when the first supplementary torque obtained by advancing the fuel injection start timing is still short of the first required torque by the second required torque, the fuel pressure is increased. to shorten the injection time width. In other words, by shortening the duration of fuel injection without changing the amount of fuel, the injection can be completed quickly. In the cylinder, combustion progresses according to the amount of injected fuel, and the expansion pressure generates a force that pushes the piston down. However, if the injection time width is long, the piston will burn to a position far below the top dead center. This is inefficient. Even if the amount of fuel is the same, if the injection time width is shortened by increasing the fuel pressure, fuel injection ends when the piston position is closer to the top dead center, and combustion ends when the piston position is closer to the top dead center. can let Therefore, when the position of the piston is closer to the top dead center, the expansion pressure can generate a force that pushes the piston down, so that the generated torque can be increased without increasing the amount of fuel.

When the generated torque is increased by increasing the fuel pressure, there is a limit to how high the fuel pressure can be, so there is a limit to the torque that can be increased (second supplementary torque). According to the sixth invention, when the second supplementary torque obtained by increasing the fuel pressure is still short of the second requested torque by the third requested torque, the amount of fuel is increased. The first supplementary torque, which is increased by advancing the fuel injection start timing, and the second supplementary torque, which is increased by increasing the fuel pressure, do not change the fuel amount. A small amount of fuel (fuel correction amount) is sufficient. Therefore, compared with the case where the generated torque is increased only by increasing the amount of fuel without adjusting the fuel injection start timing or the fuel pressure, it is possible to suppress a decrease in fuel consumption.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating an example of an overall schematic configuration of a system having a control device for an internal combustion engine of the present invention (system having two superchargers); Control that switches from single turbocharging control (supercharging with only the first turbocharger) to twin turbocharging control (supercharging with the first and second turbochargers) and a drop in supercharging during the switching transition period and FIG. 11 is a diagram illustrating an example of torque drop. FIG. 4 is a diagram for explaining total loss torque; 4 is a flowchart for explaining an example of a processing procedure (a processing procedure for obtaining each correction amount) of a control device; 4 is a flowchart illustrating an example of a processing procedure of a control device (a processing procedure of supercharging control switching processing); 4 is a flowchart for explaining an example of a processing procedure of a control device (a processing procedure for reflecting an injection start timing correction amount in control); 4 is a flowchart for explaining an example of a processing procedure of a control device (a processing procedure for reflecting a fuel pressure correction amount in control); 4 is a flowchart for explaining an example of a processing procedure of a control device (a processing procedure for reflecting a fuel correction amount in control); 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 a torque drop occurs in a switching transient 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 timing is advanced (first supplement) with respect to the state shown in FIG. 9 will be described. It is an image figure. FIG. 11 is an image diagram illustrating an example of the expansion pressure state in the cylinder, the fuel injection timing, and the fuel pressure state when the fuel pressure is further increased from the state shown in FIG. 10 (second supplement). FIG. 12 is an image diagram illustrating an example of the expansion pressure state in the cylinder, the fuel injection timing, and the fuel pressure state when the fuel amount is further increased from the state shown in FIG. 11 (third supplement). FIG. 2 is a diagram illustrating how the drop in output torque shown in FIG. 2 is compensated for by the first compensation to advance the fuel injection start timing, the second compensation to increase the fuel pressure, and the third compensation to increase the fuel amount. be.

● [Example of schematic configuration of entire internal combustion engine system (Fig. 1)]
Embodiments for carrying out the present invention will be described below with reference to the drawings. First, with reference to FIG. 1, an example of a schematic configuration of the entire internal combustion engine system having a control device 70 for the internal combustion engine will be described. In the description of the present embodiment, an internal combustion engine 10 (for example, a diesel engine) mounted on a vehicle is used as an example of the internal combustion engine. Also, in the example of the internal combustion engine system shown in FIG. , the serial supercharging operation of the second supercharger 32 and the first supercharger 31 is also possible.

The entire system will be described below in order from the intake side to the exhaust side. An intake flow rate detecting means 21 (for example, an intake flow rate sensor) is provided on the inflow side of the intake pipe 11A. The intake flow rate detection means 21 outputs a detection signal corresponding to the flow rate of the air taken in by the internal combustion engine 10 to the control device 70 . The outflow side of the intake pipe 11A is bifurcated into 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). An outflow side of an 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 joins the outflow side of the intake pipe 11C2 and is 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 turbocharger 32 (second turbocharger). The outflow side of the compressor 32A is bifurcated into an intake pipe 11C2 and an 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 joins the outflow side of the intake pipe 11C1 and is connected to the inflow side of the intake pipe 11D. An intake switching valve 62 that opens and closes the intake pipe 11C2 based on a control signal from the control device 70 is provided in the intake pipe 11C2. The outflow side of the intake bypass pipe 11CB is connected to the intake pipe 11B1. The intake bypass pipe 11CB is also 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 a control signal from the control device . 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 open and the intake bypass valve 61 is closed, the compressor 32A compresses the air taken in from the intake pipe 11B2 and discharges it 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 closed and the intake bypass valve 61 is open, the compressor 32A compresses the air taken in from the intake pipe 11B2 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. Any one of the intake pipe 11C1, the intake pipe 11D, and the intake manifold 11E downstream of the compressor 31A of the first supercharger 31 is provided with a supercharging pressure detecting means 22A (for example, a pressure sensor) for detecting the supercharging pressure. ) is provided. The boost pressure detection means 22A outputs a detection signal corresponding to the pressure of the supercharged intake air to the control device 70 .

An 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-43H are provided for each cylinder. Fuel is supplied to the injectors 43A-43H from the common rail 42 through fuel pipes, and the injectors 43A-43H are driven by control signals from the control device 70 to inject fuel into their respective cylinders.

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

The internal combustion engine 10 is provided with a rotation detection means 25 (for example, a rotation sensor), a coolant temperature detection means 24 (for example, a temperature sensor), and the like. The rotation detection means 25 outputs a detection signal corresponding to the rotational speed of the crankshaft of the internal combustion engine 10 (that is, the engine rotational speed) to the control device 70 . The coolant temperature detection means 24 detects the temperature of the cooling coolant circulating 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 exhaust manifolds 12A1 and 12A2 is connected to the exhaust side of the internal combustion engine 10, the inflow side of an exhaust pipe 12B1 is connected to the outflow side of the exhaust manifold 12A1, and the inflow side of an 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. An exhaust switching valve 63 that opens and closes the exhaust pipe 12B2 based on a control signal from the control device 70 is provided in the exhaust pipe 12B2. An exhaust bypass pipe 12BB is connected to the exhaust pipes 12B1 and 12B2 to guide the exhaust in the exhaust pipe 12B2 to the exhaust pipe 12B1 when the exhaust switching valve 63 is closed.

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 detection means 22B (for example, a pressure sensor) for detecting the pressure of the exhaust in the exhaust pipe 12C1, and an exhaust temperature detection 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 detection means 22B outputs a detection signal corresponding to the detected pressure to the control device 70, and the exhaust temperature detection means 26 outputs a detection signal to the control device 70 corresponding to the detected temperature.

The turbine 31B of the first turbocharger 31 is provided with a variable nozzle 31C capable of adjusting the flow velocity of the exhaust that drives the turbine 31B to rotate. It is operated by a driving means 31D (for example, an electric motor). Further, the nozzle opening degree detection means 31E (for example, a rotation angle sensor) outputs a detection signal corresponding 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 drive means 31D so that the opening of the variable nozzle 31C obtained based on the detection signal from the nozzle opening detection means 31E becomes the target nozzle opening. The variable nozzle 32C of the turbine 32B of the second supercharger 32, the nozzle drive means 32D, and the nozzle opening degree detection means 32E are also the same, so descriptions thereof will be omitted.

The outflow side of the oxidation catalyst 51 is connected to the inflow side of the DPF 52 (particle collection 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 SCR 53, and the DPF 52 collects fine particles in exhaust gas. Further, the DPF 52 is provided with 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 detection 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 controller 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 detection means 22C.

The urea SCR 53 reduces and purifies NOx (nitrogen oxides) in exhaust gas using urea injected from a urea water addition valve (not shown).

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

The atmospheric pressure detection means 22D (for example, an atmospheric pressure sensor) is provided in the control device 70, for example, 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 detection means 27 (for example, an accelerator pedal depression angle sensor) is provided on the accelerator pedal, and outputs a detection signal to the control device 70 according to the amount of depression of the accelerator pedal by the driver.

● [Switching of supercharging control and example of drop in boost pressure and torque during switching transition period (Fig. 2, Fig. 3)]
In FIG. 2, the turbocharging control is changed from 1 turbo (supercharging only with the first turbocharger 31 (see FIG. 1)) to 2 turbo (first turbocharger 31 and second turbocharger 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, the switching condition for switching from 1 turbo to 2 turbo is satisfied at time Ta, and supercharging control is performed with 2 turbo after time Tb. shows an example. The time Ta to Tb is the time during switching from 1-turbo to 2-turbo.

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

At time Ta, the control device 70 determines that the switching condition for switching from the 1-turbo supercharging control to the 2-turbo supercharging control is established. In this case, the control device 70 temporarily connects the second supercharger 32 and the first supercharger 31 in series for supercharging as described below in order to suppress a drop in supercharging. In this case, the control device 70 controls the intake bypass valve 61 to open, the intake switching valve 62 to close, and the exhaust switching valve 63 to open. Note that this state is maintained until the switching time elapses from the time Ta, and supercharging is performed by connecting the second supercharger 32 and the first supercharger 31 in series (see FIGS. 1 and 2). ).

After the time Tb when the switching time has elapsed from the time Ta, the control device 70 determines that supercharging control is to be performed with 2 turbos. In this case, the control device 70 controls the intake bypass valve 61 to be closed, the intake switching valve 62 to be open, and the exhaust switching valve 63 to be open. 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 transitional state time (corresponding to the transitional switching period) from the time Ta when switching from 1 turbo to 2 turbo is started to the time Tc after the time Tb when switching to 2 turbo. ), the turbocharging pressure drops because the rotation speed of the turbine of the second supercharger has not increased sufficiently. 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 he or she can feel the drop in the output torque because it accompanies the shock of a vehicle equipped with an internal combustion engine. As will be described below, the decrease in the output torque is suppressed to such an extent that the user cannot perceive it by the processing of the control device described in the present embodiment.

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

Cooling loss torque is the amount of heat (heat loss) that is lost from the cylinder and piston when the fuel injected into the cylinder collides with the cylinder and piston before atomization as the boost pressure drops. is. This cooling loss torque can be calculated by acquiring and analyzing various experimental data for the coolant temperature and boost pressure of the actual internal combustion engine, and deriving a method for calculating the cooling loss torque according to the coolant temperature and boost pressure. 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 during the transient state time. As will be described later, the control device can estimate the heat loss torque that is lost based on the heat loss increase due to the drop in supercharging in the heat loss of the piston and cylinder of the internal combustion engine.

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

The pump loss torque is the torque determined by the intake and exhaust side pressures and the area of the top surface of the piston when the piston pumps the intake air from the intake manifold and pumps the exhaust gas to the exhaust manifold. be. If the supercharging pressure drops, the amount of force for suction will increase, so if the supercharging pressure drops, the pump loss will increase. 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 during the transient state time. The control device can estimate the pump loss torque, which is lost based on the increase in the pump loss caused by the drop in supercharging, in the pump loss based on the intake and exhaust pump operations by the piston of the internal combustion engine, as described later. .

● [Processing procedure of the 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 using the flow charts shown in FIGS. 4 to 8. FIG. The process shown in FIG. 4 is activated, for example, at predetermined time intervals (for example, intervals of several [ms] to several tens [ms]). proceed.

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

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

[SB000: Supercharging control switching process]
At step SB010 shown in FIG. 5, the control device 70 determines whether or not 1-turbo supercharging control is currently being performed (single-turbocharging control in which only the first supercharger is supercharged). If the supply control is being performed (Yes), the process proceeds to step SB020, and if the 1-turbo supercharging control is not being performed (No), the process proceeds to step SB110. Note that the processing of SB000 shown in FIG. and the second turbocharger), the details of step SB110, which is the process of switching from 2-turbocharging control to 1-turbocharging control, are shown. Description is omitted.

When the process proceeds to step SB020, the control device 70 determines whether or not a condition for switching from the 1-turbo supercharging control to the 2-turbo supercharging control is satisfied based on the operating state of the internal combustion engine. 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 in operation. If not (No), the process proceeds to step SB040.

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

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

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

At step SB070A, control device 70 stops and initializes the switching timer, terminates the processing shown in FIG. 5, and advances the processing to step S025 shown in FIG.

When the process proceeds to step SB060B, it means that switching from 1-turbo supercharging control to 2-turbo supercharging control is in progress, and supercharging is performed by serially connecting the second turbocharger and the first turbocharger. This is the case. The control device 70 controls the intake bypass valve 61 to open, controls the intake switching valve 62 to close, controls the exhaust switching valve 63 to open (see FIG. 2), and ends the processing shown in FIG. Then, the process proceeds to step S025 shown in FIG.

When the process proceeds to step SB060C, it is the case of maintaining (continuing) the 2-turbo supercharging control, and is the case of performing supercharging with both the first supercharger and the second supercharger in parallel. be. Control device 70 controls intake bypass valve 61 to close, intake switching valve 62 to open, exhaust switching valve 63 to open (see FIG. 2), and proceeds to step SB070C.

At step SB070C, control device 70 stops and initializes the switching timer, terminates the processing shown in FIG. 5, and advances the processing to step S025 shown in FIG.

The control means 71, which executes the processes of steps SB010 to SB070C, switches the number of superchargers used for supercharging control according to the operating state of the internal combustion engine. Equivalent.

At step S025 shown in FIG. 4, the control device 70 determines whether or not the switching start flag (turned ON at step SB040 in FIG. 5) is ON. If the switching start flag is ON (Yes ) advances the process to step S030, and if the switching start flag is not ON (No), the process advances 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. The current coolant temperature is stored, the current fuel amount is stored in the pre-switching fuel amount, the current injection time width is stored in the pre-switching injection time width, the current fuel pressure is stored in the pre-switching fuel pressure, and the pre-switching rpm is stored. The current speed is stored in the current intake flow rate, the current intake flow rate is stored in the pre-switching intake flow rate, the current exhaust pressure is stored in the pre-switching exhaust pressure, the current exhaust temperature is stored in the pre-switching exhaust temperature, and the current nozzle opening is stored in the pre-switching nozzle opening. The nozzle opening is stored, the current differential pressure is stored as the pre-switching differential pressure, the current atmospheric pressure is stored as the pre-switching atmospheric pressure, and the process proceeds to step S035. Various physical quantities stored in step S030 are used when estimating various torque losses in steps S050 to S065. Note that physical quantities stored as "before switching" are not limited to these.

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

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

When proceeding with step S045, the control device 70 determines whether or not the switching transient timer is equal to or shorter than the transient state time (switching transient period) (see FIG. 2), and if it is equal to or shorter than the transient state time (Yes). advances the process to step S050, and if the transient state time is exceeded (No), advances the process to step S070. The value of the transient state time (switching transient period) has been set to an appropriate value through various experiments using actual vehicles. As shown in FIG. This is the time (period) during which the boost pressure and the output torque drop. For example, the transient state time (switching transient 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 advances the process to step S165.

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

In step S055, control device 70 estimates the exhaust torque loss (see FIG. 3), and proceeds to step S060. For example, the control device 70 calculates the exhaust loss torque from the map value corresponding to the exhaust flow rate and the exhaust pressure (exhaust manifold internal pressure) and the differential pressure between the DPF, etc., obtained by various experiments and various simulations using an actual vehicle. can be estimated. The control device 70 uses the map, the pre-switching exhaust gas flow rate (calculated from the pre-switching intake air flow rate and the pre-switching exhaust gas temperature), the pre-switching exhaust pressure, the pre-switching differential pressure, the pre-switching nozzle opening, etc. The torque loss is estimated, and the map, current exhaust flow rate (calculated from current intake flow rate and current exhaust temperature), current exhaust pressure, current differential pressure, current nozzle opening, etc. are used to estimate (current) exhaust torque loss. 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. By subtracting the (current) exhaust loss torque from the (before switching) exhaust loss torque, the control device 70 can estimate the reduced exhaust torque loss compared to before switching. The method for estimating the reduced exhaust loss torque is not limited to the above method.

In step S060, control device 70 estimates the pump loss torque (see FIG. 3), and advances the process to step S065. For example, the control device 70 uses map values corresponding to the supercharging pressure and exhaust pressure (exhaust manifold internal pressure) obtained by various experiments and various simulations using an actual vehicle, and the supercharging pressure and the exhaust pressure. Pump loss can be estimated from the area of the top surface of the piston. The control device 70 estimates the pump loss torque (before switching) using the map, the pre-switching supercharging pressure and pre-switching exhaust pressure, the pre-switching supercharging pressure, the pre-switching exhaust pressure, the area of the piston top surface, etc. Using the map, current boost pressure and current exhaust pressure, current boost pressure, current exhaust pressure and the area of the top surface of the piston, etc., the (current) pump loss torque is estimated. 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. By subtracting the (before switching) pump loss torque from the (current) pump loss torque, the control device 70 can estimate the increased pump loss torque compared to before switching. The method for estimating the increased pump loss torque is not limited to the above method.

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

The control means 71, which executes the processes of steps S040 to S065, changes the number of superchargers from the state where the supercharging drops immediately after switching the number of superchargers by using the supercharging switching means 71A (see FIG. 1). It corresponds to the total loss torque estimating means 71B (see FIG. 1) for estimating the total torque loss, which is the torque loss due to the drop in supercharging, during the switching transition period until reaching the supercharging state.

In step S110, control device 70 calculates the first required torque based on the total torque loss, 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 torque loss. It should be noted that the predetermined torque is a reduction in torque that is not felt by the user. After that, in steps S115 to S160B, the supplementary torque for supplementing the first required torque is obtained in order. Compensation torque is obtained in three stages. First, compensation is performed with a first compensation torque that advances (advances) the fuel injection start timing. If the torque is insufficient with the first compensating torque, the second compensating torque that further increases the fuel pressure is added to compensate. When the torque is insufficient even with the first supplementary torque and the second supplementary torque, the third supplementary torque for further increasing the fuel amount is added to compensate.

The control means 71 that executes the process of step S110 described above corresponds to the first demand torque calculation means 71C (see FIG. 1) that calculates the first demand torque according to the estimated total torque loss during the switching transition period. ing.

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

The control means 71 that executes the process of step S115 described above calculates the first supplemental torque, which is torque increased according to the fuel injection start timing advanced based on the injection start timing correction amount, during 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 an injection start timing correction amount (injection advance angle increase value) according to the first supplementary torque, and advances the process to step S125. For example, when the first supplementary 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, when the first supplementary torque is 25 [Nm], for example, the control device 70 controls the map for 20 [Nm], the injection advance angle increase value obtained from the current rotation speed and the current fuel amount, and the map for 30 [Nm]. and the injection advance angle increase value obtained from the current engine speed and the current fuel amount are interpolated to find the injection advance angle increase value for 25 [Nm] and store it in the injection start timing correction amount.

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

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

The control means 71 that executes the process of step S125 described above is a second demand torque calculation means that calculates the second demand torque that is the torque that the first supplement torque is insufficient for the first demand torque in the switching transient period. 71G (see FIG. 1).

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

When the process proceeds to step S135, control device 70 determines the second supplement torque for the second required torque, and proceeds to step S140A. The second supplementary torque is torque obtained by increasing the fuel pressure and shortening the fuel injection time width. 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], each of 10 [Nm], 20 [Nm], and 30 [Nm] Obtained fuel pressure increase value maps (three maps of 10 [Nm] map, 20 [Nm] map, and 30 [Nm] map) are prepared. Each fuel pressure increase value map is a map in which a fuel pressure increase value is set according to, for example, the rotational speed and fuel amount of the internal combustion engine. For example, when the second required torque is 40 [Nm], the control device 70 determines the second supplementary torque to be the upper limit of 30 [Nm], and when the second required torque is 25 [Nm], the second supplementary torque is determined to be 30 [Nm]. Torque is determined as 25 [Nm]. The value of the second compensating 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 described above, in the switching transient period, when there is the second required torque, the torque increased according to the fuel pressure increased based on the fuel pressure correction amount. It corresponds to the second compensating torque calculation means 71J (see FIG. 1) that calculates the second compensating torque.

In step S140A, control device 70 calculates a fuel pressure correction amount (fuel pressure increase value) corresponding to the second compensation torque, and proceeds to step S145. For example, when the second compensation torque is 30 [Nm], the control device 70 obtains the 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. For example, when the second supplementary torque is 25 [Nm], the control device 70 uses the map for 20 [Nm], the fuel pressure increase value obtained from the current rotation speed and the fuel amount for this time, and the map for 30 [Nm]. A 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 current fuel amount, and stored in the fuel pressure correction amount.

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

In step S145, control device 70 obtains a third requested torque (≧0) obtained by subtracting the second supplemental torque from the second requested torque, and advances the process to step S150. Since the second supplementary torque has an upper limit, the third required torque is the torque that is insufficient in the second supplementary torque with respect to the second required torque.

The control means 71 that executes the process of step S145 described above, when there is the second required torque in the switching transient period, adjusts the third required torque, which is the torque that the second supplementary torque is insufficient for the second required torque. It corresponds to the third required torque calculating means 71K (see FIG. 1).

In step S150, the control device 70 determines whether there is a third torque request (whether it is greater than zero), and if there is a third torque request (Yes), the process proceeds to step S155, and the third If there is no required torque (zero) (No), the process proceeds to step S160B.

When the process proceeds to step S155, control device 70 determines the third supplement torque for the third required torque, and proceeds to step S160A. The third compensation torque is torque obtained by increasing the amount of fuel, and the upper limit value can sufficiently compensate for the total torque loss. Therefore, the control device 70 determines the value of the third supplemental torque as the value of the third required torque. For example, when the third requested torque is 25 [Nm], the third supplementary torque is determined to be 25 [Nm]. For example, from various experiments and various simulations using an actual vehicle, a fuel increase of 10 [Nm], 20 [Nm], 30 [Nm], 40 [Nm], 50 [Nm], etc. can be obtained. Value maps (five maps of 10 [Nm] map, 20 [Nm] map, 30 [Nm] map, 40 [Nm] map, and 50 [Nm] map) are prepared. Each fuel amount increase value map is a map in which, for example, a fuel amount increase value corresponding to the rotational speed and fuel amount of the internal combustion engine is set.

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

The control means 71 that executes the processing of steps S150 to S160A described above has a fuel correction amount calculation means 71L that calculates the fuel correction amount based on the third required torque when there is the third required torque during the switching transition period. (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 step S160B.

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

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

It should be noted that the process of reflecting 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 FIG. 6 will be described.

● [Procedure for reflecting injection start timing 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, in [fuel injection timing processing], steps SC010, SC020A, and SC020B are newly added to the existing step SC030. When executing the [fuel injection timing process], control device 70 advances the process to step SC010.

At step SC010, the control device 70 determines whether or not there is an injection start timing correction amount (whether it is zero). 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 a value obtained by adding the injection start timing correction amount to the normal injection timing as the target injection start timing, and proceeds the process to step SC030. The normal injection timing is a value calculated by an existing process (not shown) by the control device 70 according to the operating state of the internal combustion engine. is.

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

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

The control means 71 that executes the processing of steps SC010 to SC030 described above is an injection start timing changing means that advances the fuel injection start timing from the normal injection timing based on the calculated injection start timing correction amount in the switching transition period. 71E (see FIG. 1).

[Fuel pressure processing (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 the [fuel pressure process], the control device 70 advances the process to step SD010.

In step SD010, the control device 70 determines whether or not there is a fuel pressure correction amount (zero or not), and if there is a fuel pressure correction amount (Yes), the process proceeds to step SD020A, and the fuel pressure correction amount is not present (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 as the target fuel pressure, and proceeds the process to step SD030. It should be noted that the normal fuel pressure is a value calculated by existing processing (not shown) by the control device 70 according to the operating state of the internal combustion engine.

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

When the process (existing process) proceeds to step SD030, the control device 70 controls the fuel pressure regulating pump 41 so as to achieve the target fuel pressure, and ends the process.

The control means 71 that executes the processing of steps SD010 to SD030 described above increases the fuel pressure based on the calculated fuel pressure correction amount (higher than the normal fuel pressure Fpn) during the switching transient period. 71I (see FIG. 1).

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

At step SE010, the control device 70 determines whether or not there is a fuel correction amount (zero or not). (No) advances the process to step SE020B.

When the process proceeds to step SE020A, 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 step SE030. It should be noted that the normal fuel amount is a value calculated by existing processing (not shown) by the control device 70 according to the operating state of the internal combustion engine.

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

When the process (existing process) proceeds to step SE030, the control device 70 acquires the current fuel pressure and converts the target fuel amount into an 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 timing becomes the converted injection time width, and ends the process.

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

Below, the fuel injection start timing 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, and pressure in the combustion process in the cylinder in [before correction], which is the state before implementing the first, second, and third compensation [third compensation] to increase the amount. Describe the state.

● [Example of the 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 position of the piston (crank angle position) for the target cylinder. , fuel pressure, and fuel quantity.

FIG. 9 shows the state before execution of the above [first compensation], [second compensation], and [third compensation]. advance 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).

As for the fuel injection pulse, a small amount of fuel that promotes combustion is executed by pre-injection P1, P2, etc. from slightly before compression top dead center of the target cylinder. 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 is combusted to generate an expansion pressure Pn. The advance amount θsn (normal injection timing) of the injection start timing of the main injection M1 is set so that the peak pressure Pp, which is the peak of the expansion pressure Pn, is retarded by the amount θpn from the compression top dead center.

● [Example of the state of the first compensation (Fig. 10)]
FIG. 10 shows a state in which the above [first supplement] is being executed, and the fuel injection start timing of the main injection M1 is changed by the advance angle θsn (normal injection timing) is advanced to an advance amount (θsn+Δθs) (Δθs is an injection start timing correction amount). Note that, in the example shown in FIG. 10, the fuel injection start timings of the pre-injections P1 and P2 are also advanced as the fuel injection start timing of the main injection M1 is advanced.

As the fuel injection start timing of the main injection M1 is advanced, the combustion is also advanced, 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 angle side. In other words, since the peak pressure Pp1 is generated at a position where 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 forward or backward with respect to the normal injection timing (advance angle θsn). Since the position of the peak pressure Pp1 must not be on the advance side of the compression top dead center (left side of the compression top dead center in FIG. 10), there is a limit to the injection start timing correction amount Δθs.

● [Example of the state of the second compensation (Fig. 11)]
FIG. 11 shows a state in which the above [second compensation] is being executed, and from the [first compensation] state shown in FIG. ) (ΔFp is the fuel pressure correction amount). Since the fuel pressure is increased, even if the fuel amount (normal fuel amount Qmn) does not change, 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. 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 compression top dead center. Therefore, the inflation pressure Pn2 can be raised at substantially the same timing as the inflation pressure Pn1, and the angular width Wn2 of the inflation pressure Pn2 can be narrower than the angular width Wn1 of the inflation pressure Pn1. That is, since the expansion pressure Pn2 can be generated at a position closer to the compression top dead center of the piston, the torque can be increased without increasing the amount of fuel. The control device can adjust the generated torque by adjusting the fuel injection time width by adjusting the fuel pressure higher or lower than the normal fuel pressure Fpn. Since the upper limit of the fuel pressure is determined by various factors, the fuel pressure correction amount ΔFp also has a limit.

● [Example of the state of the third compensation (Fig. 12)]
FIG. 12 shows a state in which the above [third compensation] is being executed, and from the [second compensation] state shown in FIG. ) (ΔQm is the fuel correction amount). Since the fuel amount 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 increased 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 increasing or decreasing the amount of fuel injected into the cylinder with respect to the normal fuel amount Qmn. In addition, since the torque that is insufficient even in the first and second supplements is compensated by the third supplement, 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). First of all, there is nothing.

● [Example of how the drop in output torque is compensated by the first compensation, second compensation, and third compensation (Fig. 13)]
FIG. 13 shows how the drop in the output torque shown in FIG. 2 is compensated for by the first compensation, second compensation, and 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 for by the second compensation.

After time Ta, the output torque begins to drop, and at time T1 when the amount of torque drop is equal to or less than TQ1, the torque is compensated only by the injection start timing correction amount (first compensation).

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

At time T3 following time T2, the amount of torque drop exceeds TQ1+TQ2, so the torque is be supplemented. In this case, TQ1 is compensated by the first compensation, TQ2 is compensated by the second compensation, and the amount exceeding TQ1+TQ2 is compensated by the third compensation.

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

At time T5 following time T4, the torque drop amount is equal to or less than TQ1, 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 are possible without changing the gist of the present invention. be. Moreover, the internal combustion engine system is not limited to the example shown in 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 turbochargers, the first turbocharger and the second turbocharger, has been described as an example. Also, it is possible to apply the present invention for suppressing a drop in torque during a switching transitional period immediately after switching the number of superchargers. Further, in the description of the present embodiment, an example of a configuration in which the first turbocharger and the second turbocharger supercharge in parallel (a configuration in which supercharging can be performed in series) has been described. Whether the turbochargers are configured to supercharge in parallel or in series, this system 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 the plurality of superchargers are turbochargers has been described. It may be a charger, and it is possible to apply the present invention for suppressing a drop in torque during a switching transitional period immediately after switching the number of superchargers.

In the description of the present embodiment, the total torque loss was obtained based on the cooling loss torque, the exhaust torque loss, and the pump loss torque. It may be obtained based on exhaust torque loss, or cooling loss torque and pump loss torque, or cooling loss torque.

In the description of the present embodiment, an example was described in which the first compensation for advancing the injection start timing, the second compensation for increasing the fuel pressure, and the third compensation for increasing the fuel amount were performed. Only the first filling and the second filling may be performed.

Also, the numerical values used in the description of the present embodiment are examples, and the present invention is not limited to these numerical values. Greater than (≧), less than (≦), greater than (>), less than (<), etc. may or may not include an 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 21 Intake flow rate detection means 22A Boost pressure 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 supercharger 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 timing correction amount calculation means 71E injection start timing change means 71F First compensation torque calculation means 71G Second required torque calculation means 71H Fuel pressure correction amount calculation means 71I Fuel pressure change means 71J Second compensation torque calculation means 71K Third demand 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)

Detecting an operating state of an internal combustion engine having two superchargers, a first supercharger and a second supercharger, and controlling an amount of fuel injected into a cylinder of the internal combustion engine based on the detected operating state. In a control device for an internal combustion engine,
The control device is
The generated torque can be adjusted by starting fuel injection at normal injection timing, which is a predetermined timing when the piston of the internal combustion engine is near the position of compression top dead center, and adjusting the amount of fuel injected into the cylinder. In addition, by adjusting the fuel injection start timing forward or backward with respect to the normal injection timing, the generated torque can be further adjusted,
supercharging switching means for switching the number of superchargers used for supercharging control according to the operating state of the internal combustion engine;
When using the supercharging switching means to increase the number of superchargers used for the supercharging control from a state where only the first supercharger is used for the supercharging control, Intake air is supplied to each of the first turbocharger and the second turbocharger within a switching transition period from the state in which the supercharging drop occurs immediately after the number is switched until the target supercharging state is reached. In addition, the intake air supercharged by the second turbocharger is introduced into the inflow path of the intake air of the first turbocharger, and the intake air is supercharged in series by the second turbocharger and the first turbocharger. After temporarily switching the intake path so as to guide the intake air supercharged by the first turbocharger to the internal combustion engine, the intake air is led to each of the first turbocharger and the second turbocharger. , the intake path is switched so that the intake air supercharged in parallel by the first turbocharger and the second turbocharger are collectively led to the internal combustion engine, and during the switching transition period , when the supercharging drops a total loss torque estimating means for estimating a total torque loss, which is a torque loss resulting from
a first request torque calculation means for calculating a first request torque corresponding to the estimated total loss torque in the switching transient period;
injection start timing correction amount calculation means for calculating an injection start timing correction amount based on the calculated first required torque in the switching transient period;
injection start timing changing means for advancing fuel injection start timing ahead of the normal injection timing based on the calculated injection start timing correction amount during the switching transition period;
having
A control device for an internal combustion engine. The control device for an internal combustion engine according to claim 1,
The total loss torque estimating means in the control device,
During the switching transition period,
estimating a cooling loss torque, which is a torque lost in the heat loss of the piston and the cylinder of the internal combustion engine, based on the increase in the heat loss caused by the drop in supercharging;
estimating the total torque loss based on the estimated cooling loss torque;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 2,
The total loss torque estimating means in the control device,
During the switching transition period,
Furthermore, estimating an exhaust loss torque, which is a torque gained based on a decrease in the exhaust loss caused by a decrease in supercharging in the exhaust loss based on the exhaust flow rate from the cylinder of the internal combustion engine,
estimating the total torque loss based on the estimated cooling loss torque and the exhaust torque loss;
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 3,
The total loss torque estimating means in the control device,
During the switching transition period,
Furthermore, estimating a pump loss torque, which is a torque lost based on an increase in the pump loss caused by a decrease in supercharging in the pump loss based on the pumping operation of the intake and exhaust by the piston of the internal combustion engine,
estimating the total torque loss based on the estimated cooling loss torque, the exhaust torque loss, and the pump loss torque;
A control device for an internal combustion engine. A control device for an internal combustion engine according to any one of claims 1 to 4,
The control device is
By adjusting the fuel pressure, which is the pressure of the fuel injected into the cylinder of the internal combustion engine, and adjusting the fuel injection time width, the generated torque can be further adjusted,
a first supplementary torque calculation means for calculating a first supplementary torque, which is torque increased according to the fuel injection start timing advanced based on the injection start timing correction amount, during the switching transient period;
a second demand torque calculation means for calculating a second demand torque, which is a torque insufficient for the first supplement torque with respect to the first demand torque in the switching transient period;
fuel pressure correction amount calculation means for calculating a fuel pressure correction amount based on the second required torque when there is the second required torque in the switching transient period;
fuel pressure changing means for increasing the fuel pressure based on the calculated fuel pressure correction amount during the switching transient period;
having
A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 5,
The control device is
Second supplementary torque calculation means for calculating a second supplementary torque, which is torque increased according to the fuel pressure increased based on the fuel pressure correction amount, when there is the second required torque in the switching transient period. When,
a third request torque calculation means for calculating a third request torque, which is a torque insufficient for the second supplement torque with respect to the second request torque when there is the second request torque in the switching transient period; ,
fuel correction amount calculation means for calculating a fuel correction amount based on the third requested torque when there is the third requested torque in the switching transient period;
fuel amount changing means for increasing the amount of fuel injected into the cylinder based on the calculated fuel correction amount during the switching transient period;
having
A control device for an internal combustion engine.

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