JP2009222007A - Engine supercharger device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means by which, a remaining EGR gas in an exhaust path is rapidly discharged in acceleration to permit an engine or a vehicle to be improved in acceleration performance. <P>SOLUTION: An engine DE is equipped with an exhaust turbosupercharger 19 and an electrically-operated supercharger 21. Besides, the engine DE is equipped with a low-pressure EGR path 42 which couples an upstream common intake path 16 of a compressor 19a in the exhaust turbosupercharger 19 and a downstream common exhaust path 26 of a turbine 19b in the same 19 to allow part of an exhaust gas to be refluxed to an intake system and further is equipped with a low-pressure EGR device 41 including a low-pressure EGR valve 44 arranged in the low-pressure EGR path 42. A control unit C allows the electric supercharger 21 to be operated when gathering speed. Here, when an engine operational status is in an EGR region, an operational revolution speed of the electric supercharger 21 is made higher than in a non EGR region to promote air scavenging at the time of gathering speed, enhancing acceleration performance. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an engine supercharger including an exhaust turbocharger and an electric supercharger.

  2. Description of the Related Art An exhaust turbocharger that supercharges an engine by using energy or pressure of exhaust gas in an exhaust passage is conventionally known. Such an exhaust turbocharger generally includes a turbine that is interposed in an exhaust passage and is rotationally driven by the pressure or flow of exhaust gas, and a compressor that is interposed in the intake passage and is rotationally driven by the turbine to increase the intake pressure. (For example, refer to Patent Document 1). And since the exhaust turbocharger does not consume engine shaft power, there is an advantage that the engine output can be increased without impairing fuel efficiency, and it is widely used especially for diesel engines.

Further, the exhaust gas of the engine contains NOx (nitrogen oxide), which is an air pollutant, and the amount of NOx generated increases as the combustion temperature of the fuel in the combustion chamber increases. In view of this, the engine usually recirculates a part of the exhaust gas in the exhaust passage as EGR gas to the intake passage mainly in a low load / low rotation region, and lowers the combustion temperature of the fuel in the combustion chamber by this EGR gas. An EGR device that reduces the amount of NOx generated is provided.
JP 2006-105034 A (paragraph [0031], FIG. 2)

  By the way, when accelerating an engine or a vehicle equipped with the engine, it is necessary to supply as much fresh air (air) or oxygen as possible to the combustion chamber in order to enhance acceleration. However, in an engine equipped with an EGR device, if EGR gas is supplied to the intake passage at the start of acceleration, even if the supply of EGR gas is stopped to increase the supply amount of fresh air, EGR gas remains in the passage. For this reason, a certain period of time, for example, seven cycles, is required for the EGR gas to exit the intake passage or the combustion chamber. During this period, there is a shortage of fresh air or oxygen, and the acceleration of the engine or the vehicle on which the engine is mounted is accelerated. There is a problem that the sex becomes worse.

  If the engine is a diesel engine, there is a problem that smoke or smoke is generated during this period due to lack of fresh air or oxygen. Therefore, in the conventional diesel engine, for example, the fuel supply amount is suppressed during a period necessary for the EGR gas to escape after the start of acceleration so as to prevent the generation of soot. There arises a problem that the acceleration performance is worsened.

  The present invention has been made to solve the above-described conventional problems, and can quickly discharge the EGR gas remaining in the exhaust passage during acceleration, thereby improving the acceleration performance of the engine or the vehicle. It is an object to be solved to provide means for enabling the above.

  An engine supercharging device according to the present invention made to solve the above-described problems includes an electric supercharger disposed in an intake passage, an exhaust turbocharger, an EGR device, an EGR control means, an electric motor And a supercharger control means. Here, the EGR device connects an intake passage upstream of the compressor of the exhaust turbocharger and an exhaust passage downstream of the turbine of the exhaust turbocharger, and removes a part of the exhaust gas in the exhaust passage (EGR It has an EGR passage for returning to the intake passage (as gas) and an EGR valve disposed in the EGR passage. The EGR control means controls the exhaust gas recirculation amount via the EGR valve in accordance with the operating state of the engine. The electric supercharger control means operates the electric supercharger at the time of acceleration, and when the operating state of the engine is in the EGR region, the operation speed of the electric supercharger is larger than that in the non-EGR region. Increase the number.

  In the engine supercharging device according to the present invention, the EGR valve and the electric supercharger are preferably controlled based on an intake model set based on at least the accelerator opening. Here, the intake model was set to have the same characteristics as the characteristics of the actual equipment that affects the intake state of the actual engine so that the same intake state as the actual engine intake state can be obtained. It is configured by combining a plurality of types of virtual devices, and is configured to determine control values for the virtual devices based on preset input parameters so that the actual engine intake state becomes the target intake state. preferable.

  In the engine supercharging device according to the present invention, the electric supercharger control means includes the electric supercharger when the engine operating state is in the EGR region at the time of acceleration compared to when the engine is in the non-EGR region. It is preferable that the number of pre-rotations is increased.

  According to the supercharger for an engine according to the present invention, when the operating state of the engine is in the EGR region at the time of acceleration, the electric supercharger is operated at a high rotational speed, and therefore remains in the intake passage. EGR gas is quickly discharged into the exhaust passage, and the supply amount of fresh air increases rapidly. For this reason, the acceleration performance of the engine or a vehicle equipped with the engine is enhanced, and when the engine is a diesel engine, the generation of soot is suppressed or prevented. On the other hand, when the engine operating state is in a non-EGR region during acceleration, that is, when EGR gas does not remain in the intake passage or when the remaining amount is small, the electric supercharger is operated at a low rotational speed. Unnecessary power consumption can be prevented.

  Further, when the engine operating state is in the EGR region at the time of acceleration, the electric supercharger is operated at a high speed, so that the fresh air and EGR gas supplied to the combustion chamber due to the pressure increase in the intake passage However, since oxygen remains in the EGR gas, oxygen in the EGR gas also contributes to fuel combustion. For this reason, the amount of oxygen supplied to the combustion chamber during acceleration can be quickly increased, which can also improve the acceleration performance of the engine or vehicle, and suppresses generation of soot when the engine is a diesel engine. Or it can be prevented.

  In the engine supercharging device according to the present invention, when the EGR valve and the electric supercharger are controlled based on the intake air model, it is possible to predict the destination of the engine operating state during acceleration. The EGR valve and the electric supercharger can be switched in advance to a control state suitable for the operation state at the transition destination. For this reason, the acceleration performance of the engine or the vehicle can be further increased, and when the engine is a diesel engine, the generation of soot can be more effectively suppressed or prevented.

  In the engine supercharging device according to the present invention, when the engine operating state is in the EGR region at the time of acceleration, the rotational speed of the pre-rotation of the electric supercharger is made higher than that in the non-EGR region. If the engine is a diesel engine, it is possible to further increase the acceleration of the engine or vehicle while suppressing the increase in power consumption by correcting the pre-rotation speed of the electric supercharger. Generation | occurrence | production of soot can be suppressed or prevented more effectively.

(Embodiment 1)
Embodiment 1 of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 shows a system configuration of a direct injection diesel engine DE (hereinafter referred to as “engine DE” for short) provided with a supercharging device according to Embodiment 1 of the present invention. The engine DE is a multi-cylinder (for example, four cylinders, six cylinders, etc.) engine, but only one cylinder is shown in FIG. 1, and the other cylinders are not shown.

  As shown in FIG. 1, in the engine DE, when the intake valve 1 is opened, fuel combustion air is sucked into the combustion chamber 3 from the intake port 2 (hereinafter, this air is referred to as “intake air”). That said.) The intake air in the combustion chamber 3 is adiabatically compressed by the piston 4 to be in a high pressure state, and is usually higher than the ignition temperature of the fuel. In the vicinity of the top dead center of the compression stroke, fuel (light oil or the like) is injected from the fuel injection valve 5 into the combustion chamber 3, and this fuel self-ignites and burns. Gas generated by combustion, that is, exhaust gas, is discharged to the exhaust port 7 when the exhaust valve 6 is opened. Although not shown, the fuel is supplied from the fuel tank to the fuel injection valve 5 through the common rail at a high pressure.

  A series of these operations is repeated, and the piston 4 repeats reciprocating motion in the cylinder axial direction within the cylinder 8. The reciprocating motion of the piston 4 is converted into a rotational motion (torque) of the crankshaft 10 by a link mechanism including a connecting rod 9, a crank arm (not shown), a crankpin (not shown), and the like. The rotational movement of the crankshaft 10 is taken out as engine output and drives a vehicle equipped with the engine DE, and drives auxiliary equipment such as an alternator and an air conditioner (not shown). The engine DE is driven (cranked) by the engine starter 11 at the time of starting. Although not shown, the driving force of the crankshaft 10 is transmitted to driving wheels via a transmission, a final gear, and the like.

  In the engine DE, the intake valve 1 is opened and closed by the intake valve opening / closing cam mechanism 12 at a predetermined timing. An electromagnetic intake valve cam control device 13 (VVT: variable valve timing control device) is provided for the intake valve opening / closing cam mechanism 12. The intake valve cam control device 13 can advance or retard the opening / closing timing of the intake valve 1 via the intake valve opening / closing cam mechanism 12 in accordance with a control signal from the control unit C.

  On the other hand, the exhaust valve 6 is opened and closed by the exhaust valve opening / closing cam mechanism 14 at a predetermined timing. An electromagnetic exhaust valve cam control device 15 (VVT) is provided for the exhaust valve opening / closing cam mechanism 14. The exhaust valve cam control device 15 can advance or retard the opening / closing timing of the exhaust valve 6 via the exhaust valve opening / closing cam mechanism 14 in accordance with a control signal from the control unit C.

  An intake system (intake system) that supplies intake air to the combustion chamber 3 of each cylinder of the engine DE is provided with a single common intake passage 16 that is common to all cylinders. The front end (upstream end) of the common intake passage 16 is opened to the atmosphere, and an air cleaner (not shown) that removes dust and the like in the intake air sequentially from the upstream side in the flow direction of the intake air near the front end. And an air flow sensor 17 (see FIG. 3) for detecting the flow rate of the intake air.

  Further, in the common intake passage 16, electromagnetic intake control in which the valve opening degree (that is, the cross-sectional area of the common intake passage 16) is controlled by the control unit C in order from the upstream side in the intake air flow direction. A valve 18, a compressor 19 a of the exhaust turbocharger 19, and an air-cooled intercooler 20 are provided. Here, the compressor 19a (exhaust turbocharger 19) supercharges the engine DE by pressurizing and compressing the intake air. Further, the intercooler 20 cools the intake air whose temperature has risen due to pressurization and compression (substantially adiabatic compression) of the compressor 19a.

  The common intake passage 16 branches into a first branch intake passage 16a and a second branch intake passage 16b on the downstream side of the intercooler 20, and both the branch intake passages 16a and 16b are gathered slightly downstream from the branch portion to be simply separated. One common intake passage 16 is formed. An electric supercharger 21 is provided in the first branch intake passage 16a. The electric supercharger 21 includes a compressor 21a disposed in the first branch intake passage 16a, and a motor 21b that rotates the compressor 21a when electric power is supplied from a battery (not shown) or an alternator (not shown). (Electric motor). On the other hand, the second branch intake passage 16b is provided with a check valve 22 for opening and closing the second branch intake passage 16b. Here, the check valve 22 closes the second branch intake passage 16b when the electric supercharger 21 (compressor 21a) is driven, and the second branch intake passage 16b when the electric supercharger 21 is stopped. open.

  As will be described later, the electric supercharger 21 mainly improves the acceleration of the engine DE or a vehicle equipped with the engine DE or a vehicle equipped with the turbo lag by compensating for the operation delay of the exhaust turbocharger 19 during acceleration. , EGR gas remaining in the intake system at the time of acceleration is quickly discharged to the exhaust passage, and the supply amount of fresh air is increased rapidly to increase the acceleration of the engine DE or the vehicle and to generate smoke. It is provided in order to suppress or prevent.

  The downstream end of the common intake passage 16 is connected to a surge tank 23 that attenuates the pulsation of the intake air and stabilizes the flow at the downstream side of the gathering portion of the first branch intake passage 16a and the second branch intake passage 16b. ing. A plurality of independent intake passages 24 for supplying intake air individually to the combustion chambers 3 of the respective cylinders are connected to the surge tank 23, and the downstream ends of these independent intake passages 24 are respectively connected to the intake ports 2 of the corresponding cylinders. It is connected. The surge tank 23 is provided with an intake pressure sensor 25 that detects the pressure of intake air.

  Further, the engine DE is provided with an exhaust system (exhaust system) that exhausts exhaust gas discharged from each combustion chamber 3 into the atmosphere, and this exhaust system has a single common exhaust passage common to each cylinder. 26 is provided. However, in the exhaust gas flow direction, in the vicinity of the upstream end (exhaust manifold), the exhaust system is branched for each cylinder and connected to the exhaust port 7 of the corresponding cylinder. The common exhaust passage 26 is provided with a turbine 19b of an exhaust turbocharger 19 driven by exhaust gas.

  The exhaust turbocharger 19 is a variable capacity supercharger (VGT) provided with a variable capacity mechanism capable of changing the passage cross-sectional area of the exhaust gas to the turbine 19b by a large number of movable vanes 27. The angle or direction of the movable vanes 27 is controlled by the movable vane actuator 28. Then, the control unit C changes the passage cross-sectional area of the exhaust gas via the movable vane actuator 28 and the movable vane 27, and the rotational speed of the turbine 19b (exhaust turbocharger 19), that is, the rotational speed of the blower 19a, As a result, supercharging pressure is controlled. The specific structure and function of the variable capacity mechanism of the exhaust turbocharger 19 will be described later (see FIG. 2).

  An exhaust gas purification catalyst 30 for purifying exhaust gas and a particulate filter 31 (DPF) for collecting soot (particulates) are disposed in the common exhaust passage 26 on the downstream side of the turbine 19b in the exhaust gas flow direction. An exhaust gas purification device 32 is provided. The exhaust gas purification catalyst 30 includes an oxidation catalyst (for example, a catalyst made of platinum, rhodium, palladium, etc.) that oxidizes and purifies HC and CO, and a reduction catalyst (platinum, barium, etc.) that reduces and purifies NOx. Catalyst) is supported on a support material made of, for example, zeolite. Moreover, the soot collected by the particulate filter 31 is appropriately set to an operation state in which the exhaust gas purification catalyst 31 is heated when, for example, the differential pressure before and after the particulate filter 31 exceeds a set value. Thus, for example, by performing fuel injection in the expansion stroke, it is burned and removed.

  Exhaust gas purifying device 32 (exhaust gas purifying catalyst 30) upstream and exhaust gas purifying device 32 (particulate filter 31) downstream from exhaust gas purifying device 32 (exhaust gas purifying catalyst 30), respectively. A first exhaust pressure sensor 33 and a second exhaust pressure sensor 34 for detecting the gas pressure are provided. Further, an exhaust opening / closing valve 35 for opening / closing the common exhaust passage 26 is provided in the common exhaust passage 26 on the downstream side of the particulate filter 31 or the second exhaust pressure sensor 34. The valve opening degree of the exhaust opening / closing valve 35 (that is, the passage sectional area of the common exhaust passage 26) is controlled by the control unit C.

  Further, the engine DE mainly takes a part of the relatively high-pressure exhaust gas upstream of the turbine in the common exhaust passage 26 as EGR gas for the main purpose of reducing the amount of NOx generated due to fuel combustion. A high pressure EGR device 36 is provided for refluxing the system. The high pressure EGR device 36 is provided with a high pressure EGR passage 37 serving as an EGR gas flow path. Here, the upstream end of the high-pressure EGR passage 37 as viewed in the flow direction of the EGR gas is connected to the common exhaust passage 26 at a portion upstream of the turbine 19b as viewed in the flow direction of the exhaust gas. On the other hand, the downstream end of the high-pressure EGR passage 37 is connected to the surge tank 23 in the EGR gas flow direction. In the high-pressure EGR passage 37, a water-cooled high-pressure EGR cooler 38 that cools high-temperature (for example, 600 to 800 ° C.) EGR gas in order from the upstream side in the flow direction of the EGR gas, and the supply amount of EGR gas Or a high-pressure EGR valve 39 for controlling the flow rate is provided.

  Further, the engine DE mainly receives a part of the relatively low-pressure and low-temperature exhaust gas downstream of the particulate filter 31 in the common exhaust passage 26 mainly for the purpose of reducing the amount of NOx generated due to fuel combustion. , A low pressure EGR device 41 is provided for recirculating as EGR gas to the intake system. The low pressure EGR device 41 is provided with a low pressure EGR passage 42 that serves as a flow path for EGR gas. Here, the upstream end of the low pressure EGR passage 42 as viewed in the flow direction of the EGR gas is connected to the common exhaust passage 26 at a portion between the particulate filter 31 and the exhaust opening / closing valve 35. On the other hand, the downstream end of the low-pressure EGR passage 42 as viewed in the EGR gas flow direction is connected to the common intake passage 16 at a portion between the intake control valve 18 and the compressor 19a. The low-pressure EGR passage 42 includes an air-cooled low-pressure EGR cooler 43 that cools the EGR gas in order from the upstream side in the flow direction of the EGR gas, and a low-pressure EGR valve 44 that controls the supply amount or flow rate of the EGR gas. Is provided.

  Next, a specific structure and function of the variable capacity mechanism of the exhaust turbocharger 19 which is a variable capacity supercharger (VGT) will be described with reference to FIG. FIG. 2 is a cross-sectional view of the turbine 19 b of the exhaust turbocharger 19. As shown in FIG. 2, the turbine 19 b has a turbine chamber 52, and exhaust gas flows into the turbine chamber 52 in the direction indicated by the arrow D. In the turbine chamber 52, a plurality of movable vanes 27 are arranged so as to surround the turbine blades 53 on the exhaust gas inflow side, that is, the exhaust inlet side. Each of these movable vanes 27 is rotatable around a shaft 55, and the angle or direction of these movable vanes 27 is changed by the rotation.

  Here, as shown by a solid line in FIG. 2, if the movable vanes 27 are arranged close to each other, that is, if the movable vanes 27 extend in a direction closer to the circumferential direction of the turbine blades 53, The opening of the nozzle 54 formed between the movable vanes 27 (hereinafter referred to as “vane nozzle opening”) is reduced. In particular, if the vane nozzle opening is reduced when the engine speed is low, the exhaust gas flow rate increases, and the exhaust gas flow is directed in the tangential direction (circumferential direction) of the turbine 19b, so that the supercharging efficiency increases. . However, in this case, the exhaust pressure (exhaust gas pressure) of the engine DE increases.

  Further, as indicated by phantom lines (two-dot chain lines) in FIG. 2, the movable vanes 27 are separated from each other, that is, the movable vanes 27 extend in a direction closer to the radial direction of the turbine blade 53. If it does so, a vane nozzle opening will become large. In particular, when the opening degree is increased when the engine speed is high, the flow rate of the exhaust gas can be increased, so that the supercharging efficiency is increased. The control unit C controls the angle or direction of the movable vanes 27, that is, the vane nozzle opening degree, from the fully closed position to the fully opened position via the movable vane actuator 28.

Hereinafter, the control system of the engine DE will be described.
As shown in FIG. 3, the engine DE is provided with various sensors for collecting various types of information regarding the operating state. That is, in addition to the air flow sensor 17, the intake pressure sensor 25, the first exhaust pressure sensor 33, and the second exhaust pressure sensor 34, an engine speed sensor that detects the number of revolutions of the crankshaft 10 (engine speed). 56, a crank angle sensor 57 for detecting a crank angle, an engine water temperature sensor 58 for detecting a cooling water temperature (engine water temperature) of the engine DE, an accelerator opening sensor 59 for detecting an accelerator pedal opening (accelerator opening), and an intake An intake air temperature sensor 60 that detects the temperature of the air is provided. Detection signals from these sensors are input to the control unit C as control information such as the engine DE.

  The control unit C is a comprehensive control means for the engine DE or its accessory devices including the “EGR control means” and the “electric supercharger control means” described in the section for solving the problems. Although not shown in detail, the control unit C includes an input / output unit (interface) that inputs and outputs control signals, a storage unit (ROM, RAM, and the like) that stores data and control information, and a central unit that performs various arithmetic processes. A computer including a processing unit (CPU), a timer, a counter, and the like.

  FIG. 4 shows a control system configured in the control unit C, and an identification model DM set to have the same characteristics as the actual engine DE corresponding to the actual engine DE is set. Yes. That is, the identification model DM is used to determine actual control values of various devices necessary for setting the intake state of the engine DE, that is, the state of intake air immediately before being supplied to the combustion chamber 3, to the target intake state. For this reason, a plurality of virtual devices having the same characteristics as those of various actual devices that affect the intake state are set.

  In FIG. 4, “x” is added to the reference numbers of the actual devices as these virtual devices. Specifically, as virtual devices, a virtual airflow sensor 17x corresponding to the airflow sensor 17, a virtual intake control valve 18x corresponding to the intake control valve 18, and a virtual actuator 28x corresponding to the movable vane actuator 28 of the exhaust turbocharger 19 are used. A virtual intake air temperature sensor 60x (virtual intercooler 20x) corresponding to the intake air temperature sensor 60, a virtual motor 21bx corresponding to the motor 21b of the electric work supercharger 21, a virtual intake pressure sensor 25x corresponding to the intake pressure sensor 25, an engine Virtual engine DEx (combustion model) corresponding to DE, virtual exhaust pressure sensors 33x, 34x (corresponding to the particulate filter 31) corresponding to the first and second exhaust pressure sensors 33, 34, and virtual corresponding to the high pressure EGR valve 39 Virtual low pressure EGR valve corresponding to high pressure EGR valve 39x and low pressure EGR valve 44 4x has been set.

  The control values determined in the identification model DM shown in FIG. 4 are the intake control valve opening degree in the virtual device 18x, the opening degree of the movable vane 27 in the virtual device 28x, and the electric supercharger rotation speed (in the virtual device 21bx). Or the driving current), the high pressure EGR valve opening in the virtual device 39x, and the low pressure EGR valve opening in the virtual device 44x. These determined control values are output to the corresponding actual device. As parameters for determining these control amounts, the accelerator opening detected by the accelerator opening sensor 59 and the engine speed detected by the engine speed sensor 56 are basically used. In addition, the intake air amount obtained by the virtual device 17x, the intake air temperature at the intercooler outlet obtained by the virtual device 60x (20x), the intake pressure obtained by the virtual device 25x, the combustion state obtained by the virtual device DEx, the virtual device 33x , 34x is used in addition to the above parameters.

  As is apparent from FIG. 4, in the identification model DM, a series of flows until the intake air flows from the inlet of the common intake passage 16 and becomes exhaust gas by the combustion of the fuel is the same as in the case of the actual engine DE. Thus, it has the same characteristics as those of the actual engine DE. Such an identification model DM is created in the form of “Matrabo”, for example, based on actual data obtained by actually operating the engine DE with the system shown in FIG.

  In the identification model DM, when a target oxygen concentration (or target filling amount) is given as the target inspiratory state, various control values necessary to obtain this target oxygen concentration (or target filling amount) are determined, and this Each determined control value is output to the corresponding actual device. That is, the opening degree of the intake control valve 18, the opening degree of the movable vane 27, the rotation speed (or drive current) of the electric supercharger 21, and the opening degrees of both EGR valves 39 and 44 are determined by simulation using the identification model DM. The control value is output to the corresponding actual device. Since the identification model DM is created so as to determine the control value based on the data actually obtained by operating the engine DE, the target value can be obtained by outputting the determined control value to actual devices. The oxygen concentration (target filling amount) is accurately converged.

  Thus, the control unit C, based on the various data detected by each sensor, the fuel injection valve 5, the intake valve cam control device 13, the exhaust valve cam control device 15, the intake control valve 18, the electric supercharger 21, By controlling or driving the check valve 22, the movable vane actuator 28, the exhaust opening / closing valve 35, the high pressure EGR valve 39, the low pressure EGR valve 44, etc., the fuel injection control, EGR control, supercharging pressure control, particulate filter 31 Ordinary engine control such as regeneration control is performed.

  Further, the control unit C controls the electric supercharger 29 and the low-pressure EGR valve 44 to enhance acceleration performance or prevent or suppress soot generation when the engine DE or a vehicle equipped with the engine DE is accelerated. Hereinafter, it is referred to as “electric supercharger control”). However, the control method for ordinary engine control is well known to those skilled in the art, and since such ordinary engine control is not the gist of the present invention, the description thereof is omitted. Note that the identification model shown in FIG. 4 is used in the electric supercharger control according to the second embodiment of the present invention, and is not used in the electric supercharger control in the first embodiment.

  Hereinafter, the control procedure of the electric supercharger control according to the first embodiment, which is executed by the control unit C, will be specifically described with reference to the flowchart shown in FIG. As shown in FIG. 5, in the electric supercharger control, when the control is started (start), first, in step S1, the physical property values detected by the sensors 17, 25, 33, 34, and 56 to 60 are detected. Or various signals corresponding to the detected values are read.

  Next, in step S2, it is determined whether the engine DE or the vehicle is in an accelerating state based on the accelerator opening or the increasing speed. In general, when the accelerator pedal is depressed and the engine DE starts accelerating, the turbocharger delay, that is, the turbo lag caused by the operation delay of the turbine 19b of the exhaust turbocharger 19 and the operation of the compressor 19a with respect to the depression operation of the accelerator pedal. Arise. For this reason, the intake air becomes insufficient due to a delay in the rise (supercharging) of the intake air pressure, and the engine DE cannot be accelerated quickly. Therefore, in this engine DE, when the engine DE is in an acceleration state, the electric supercharger 21 is driven to assist the increase (supercharging) of the intake air pressure, thereby preventing or suppressing the occurrence of the supercharging delay. I am doing so.

  If it is determined in step S2 that the engine DE is in an accelerated state (YES), it is determined whether or not the acceleration flag F is 1 in step S3. The acceleration flag F is set to 1 in step S7, which will be described later, when the engine DE or the acceleration of the vehicle is started, and is reset to 0 in step S11, which will be described later, when the acceleration is completed. Flag.

  When it is determined in step S3 that the acceleration flag F is not 1 (that is, 0) (NO), that is, when acceleration is started from this time, the operation state of the engine DE is changed to EGR gas in the intake system in step S4. It is determined whether or not it is in an area to be supplied (hereinafter referred to as “EGR zone”). The operating state of the engine DE in step S4 is expressed by using the engine speed and the engine load (fuel injection amount or accelerator opening) as parameters. If it is determined in step S3 that the acceleration flag F is 1 (YES), that is, if acceleration has already started before the previous time, steps S3 to S7 are skipped and step S8 described later is performed. Is executed.

  As shown in FIG. 7, in this engine DE, a region 1 (EGR rich zone), which is generally a low rotation / low load region, and a region 2 (EGR partial zone) on the higher load side or higher rotation side than the region 1 Thus, EGR gas is supplied to the intake system. In region 1, since a very large engine output is not required, the amount of EGR gas supplied to the intake system is increased to reduce the NOx generation amount as much as possible. In region 2, since a certain level of engine output is required, the amount of EGR gas supplied to the intake system is reduced to achieve both engine output and NOx reduction. In regions other than region 1 and region 2, that is, region 3 (EGR-less zone) that is generally a high load region or a high rotation region, in order to increase the engine output as much as possible, supply of EGR gas to the intake system is performed. The engine is stopped and as much fresh air as possible is supplied to the combustion chamber 3.

  If it is determined in step S4 that the operating state of the engine DE is in the EGR zone (that is, region 1 or region 2 in FIG. 7) (YES), the electric supercharger 21 is driven in step S5, Pre-rotation is performed for a preset period at a relatively high rotation speed N1 (for example, 3000 rpm). Note that the check valve 22 is closed simultaneously with the driving of the electric supercharger 21 or with a slight delay.

  On the other hand, when it is determined in step S4 that the operating state of the engine DE is not in the EGR zone (NO), the electric supercharger 21 is driven in step S6, and a relatively low rotational speed N2 (for example, 1500 rpm). Is pre-rotated for a preset period. Note that the check valve 22 is closed simultaneously with the driving of the electric supercharger 21 or with a slight delay.

  As described above, the pre-rotation speed of the electric supercharger 21 is switched in step S5 or step S6 depending on whether or not the operating state of the engine DE is in the EGR zone for the following reason. That is, when the engine DE or the vehicle is accelerated, it is necessary to supply as much fresh air or oxygen as possible to the combustion chamber in order to enhance acceleration. However, if EGR gas is supplied to the intake system before or at the start of acceleration, the EGR gas will not enter the intake system even if the supply of EGR gas is stopped to increase the supply amount of fresh air during acceleration. It remains. Therefore, in this case, the number of pre-rotations of the electric supercharger 21 is increased in step S5, the EGR gas remaining in the intake system is quickly discharged to the exhaust system, and the fresh air is quickly supplied to the combustion chamber. Or oxygen is supplied to improve acceleration.

  On the other hand, when EGR gas is not supplied to the intake system before or at the start of acceleration, almost no EGR gas remains in the intake system, so that the number of pre-rotations of the electric supercharger 21 is particularly high. It is not necessary to do so, and it is only necessary to rotate at the number of revolutions necessary to supplement the turbo lag. Therefore, in this case, in step S6, the electric supercharger 21 is rotated at a relatively low rotational speed N2, that is, at a normal rotational speed.

  Thus, after acceleration is started and the electric supercharger 21 is driven, 1 is set to the acceleration flag F in step S7. Subsequently, in step S8, it is determined whether or not the rotational speed of the electric supercharger 21 has reached a target rotational speed (target value). This target rotational speed is set to a normal operating rotational speed (for example, 50000 rpm) of the electric supercharger 21, for example. When acceleration is started from this time, the rotational speed of the electric supercharger 21 is N1 or N2, and it is clear that the target rotational speed has not been reached.

  If it is determined in step S8 that the rotational speed of the electric supercharger 21 has not reached the target rotational speed (NO), the rotational speed of the electric supercharger 21 is predetermined toward the target rotational speed in step S10. It is raised (gradual increase) at an ascending speed. Thereafter, the process returns to step S1 (return). On the other hand, if it is determined in step S8 that the rotational speed of the electric supercharger 21 has reached the target rotational speed (YES), the rotational speed of the electric supercharger 21 is held at the target rotational speed in step S9. The Thereafter, the process returns to step S1 (return).

  If it is determined in step S2 that the engine DE or the vehicle is not in an accelerated state (NO), the acceleration flag F is reset to 0 in step S11. Subsequently, in step S12, the operation of the electric supercharger 21 is stopped, and the check valve 22 is opened simultaneously or slightly before this. Thereafter, the process returns to step S1 (return).

  In this electric supercharger control, the target rotational speed is constant regardless of whether the operating state of the engine DE is in the EGR zone or not. However, the target rotational speed when the operating state of the engine DE is in the EGR zone may be higher than the target rotational speed when the engine DE is not in the EGR zone. In this case, the number of pre-rotations may be constant regardless of whether the operating state of the engine DE is in the EGR zone or not. These are the same for the second embodiment which will be described later.

  Thus, according to the supercharger or electric supercharger control of the engine DE according to Embodiment 1 of the present invention, when the operating state of the engine DE is in the EGR zone during acceleration, the electric supercharger 21 is high. Since the pre-rotation is performed at the rotational speed, the EGR gas remaining in the intake system is quickly discharged to the exhaust system, and the supply amount of fresh air increases rapidly. For this reason, the acceleration performance of the engine DE or the vehicle is enhanced, and soot generation is suppressed or prevented. Further, when the operating state of the engine DE is not in the EGR zone during acceleration, that is, when the EGR gas does not remain in the intake system, the electric supercharger 21 is pre-rotated at a low rotational speed, which is unnecessary. Power consumption can be prevented.

(Embodiment 2)
The second embodiment of the present invention will be described below. However, the mechanical configuration and functions of the engine DE in the second embodiment are the same as those in the first embodiment. In the second embodiment, the control method of the electric supercharger control by the control unit C is different from the first embodiment. Is only different. Therefore, in order to avoid duplication of explanation, only the control method of the electric supercharger control according to the second embodiment will be described below. In the electric supercharger control according to the first embodiment, the electric supercharger 21 is controlled based on the actual operating state of the engine DE. In the second embodiment, the electric supercharger control is predicted by an intake model or an identification model. The electric supercharger 21 is controlled based on the operating state of the engine DE, that is, the operating state of the engine DE is predicted in advance. Further, in the electric supercharger control according to the second embodiment, it is assumed that the operating state of the engine DE before acceleration is in the low load / low rotation region, that is, the region 1 (EGR rich zone) in FIG. is doing.

  As shown in FIG. 6, in the electric supercharger control according to the second embodiment, when the control is started (start), first, in step S21, detection is performed by each sensor 17, 25, 33, 34, 56-60. Various signals corresponding to the measured physical property values or detected values are read. Subsequently, in step S22, it is determined whether the engine DE or the vehicle is in an acceleration state based on the accelerator opening or the increasing speed.

  If it is determined in step S22 that the engine DE is in an accelerated state (YES), it is determined in step S23 whether or not the acceleration flag F is 1. The acceleration flag F is a flag similar to the acceleration flag in the electric supercharger control according to the first embodiment. When the engine DE or the acceleration of the vehicle is started, 1 is set in step S30 described later. When the acceleration is finished, it is reset to 0 in step S34 described later.

  If it is determined in step S23 that the acceleration flag F is not 1 (NO), that is, if acceleration is started from this time, in steps S24 to S26, an intake model or an identification model is used ( The future operating state of the engine DE is predicted. Specifically, first, in step S24, a target filling amount is determined based on a target filling amount map using the engine speed and the accelerator opening as parameters.

  Next, in step S25, the opening degree of the intake control valve 18, the opening degree of the movable vane 27, and the rotational speed of the electric supercharger 21 required to obtain the target filling amount by the identification model DM shown in FIG. (Or drive current), the opening of the high pressure EGR valve 39 and the opening of the constant pressure EGR valve 44 are determined. Each control value determined in this way is output to the corresponding actual device. Subsequently, in step S26, the operating state of the engine DE after a predetermined time is predicted. That is, when a predetermined time has elapsed from the present time, it is predicted at which point in the two-dimensional coordinate system that the engine DE operating state and the engine load shown in FIG. The

  In this way, after the operation state of the engine DE after a predetermined time is predicted, in step S27, it is determined whether or not the predicted operation state of the engine DE is in the region 2 in FIG. 7, that is, the EGR partial zone. Determined. Here, if it is determined that the predicted operating state of the engine DE is in the EGR partial zone (YES), the electric supercharger 21 is driven in step S28, and a relatively low rotational speed M1 (for example, (1500 rpm) for a preset period. Note that the check valve 22 is closed simultaneously with the driving of the electric supercharger 21 or with a slight delay.

  On the other hand, if it is determined in step S27 that the predicted operating state of the engine DE is not in the region 2, that is, the EGR partial zone (NO), in other words, the region 3 in FIG. If it is determined that the electric supercharger 21 is present, the electric supercharger 21 is driven in step S29, and is pre-rotated for a predetermined period at a relatively high rotational speed M2 (eg, 3000 rpm). Note that the check valve 22 is closed simultaneously with the driving of the electric supercharger 21 or with a slight delay.

  As described above, in step S28 or step S29, the number of pre-rotations of the electric supercharger 21 is changed depending on whether the predicted operating state of the engine DE is in the EGR partial zone or the EGR less zone. The reason is as follows. That is, for example, as shown by an arrow P1 in FIG. 8, when acceleration is started from the A region in the EGR rich zone, the predicted operating state of the engine DE is the C region in the EGR less zone. The engine DE or the vehicle is accelerated with a relatively large acceleration, and the supply of EGR gas to the intake system is expected to be stopped. Therefore, in this case, the electric supercharger 21 is pre-rotated at a relatively high rotational speed M2 so that the EGR gas in the intake system can be quickly discharged to the exhaust system.

  On the other hand, as shown by the arrow P2 in FIG. 8, when the acceleration is started from the A region in the EGR rich zone and the predicted operating state of the engine DE is the B region in the EGR partial zone, The engine DE or the vehicle is accelerated with a relatively small acceleration, and the supply of EGR gas to the intake system is expected to continue at a small flow rate. Therefore, it is not necessary to exhaust the EGR gas from the intake system as quickly as when the operating state of the engine DE is predicted to shift to the EGR-less zone. Therefore, the electric supercharger 21 is pre-rotated at a relatively low rotational speed M1.

  As shown in FIG. 8, when the acceleration is started from the operating state in the A region in the EGR rich zone, the engine DE is operated by the acceleration by using the intake model or the identification model (model base control), for example, EGR partial. It is possible to easily predict whether to move to the B area in the zone or to move to the C area of the EGR-less zone. That is, in this electric supercharger control, by predicting the acceleration requested by the driver according to the accelerator acceleration in advance, the necessary torque is calculated from this acceleration and the flow rate of fuel required to generate the torque is calculated. And the amount of heat that can be obtained from the fuel is calculated to ensure the amount of air necessary to meet the driver's requirements.

  Generally, in a diesel engine, the oxygen concentration in the EGR gas is not zero even when operated in an EGR rich zone. When the electric supercharger 21 is operating at the time of acceleration, the supply amount of fresh air and EGR gas supplied to the combustion chamber 3 both increases due to the pressure increase in the intake system, but the EGR gas Since oxygen remains, oxygen in the EGR gas also contributes to fuel combustion. For this reason, the amount of oxygen supplied to the combustion chamber 3 during acceleration can be quickly increased.

  In FIG. 9, when supercharging is performed by the composition R1 of the mixed gas of fresh air (intake air) and EGR gas supplied to the combustion chamber 3 in the A region in FIG. 5 conceptually shows the composition R2 of the mixed gas of fresh air and EGR gas supplied to the combustion chamber 3 in the B region or the C region. As is clear from FIG. 9, it can be seen that the combustible air contained in the EGR gas occupies a considerable proportion due to the supercharging by the electric supercharger 21. This combustible air contributes to the combustion of the fuel, the combustibility of the fuel is enhanced, the acceleration performance is improved, and the generation of soot is prevented.

  Thus, after acceleration is started and the electric supercharger 21 is driven, 1 is set to the acceleration flag F in step S30. Subsequently, in step S31, it is determined whether or not the rotational speed of the electric supercharger 21 has reached a target rotational speed (target value). This target rotational speed is set to a normal operating rotational speed (for example, 50000 rpm) of the electric supercharger 21, for example. In addition, when acceleration is started from this time, the rotational speed of the electric supercharger 21 is M1 or M2, and it is clear that the target rotational speed has not been reached. If it is determined in step S23 that the acceleration flag F is 1 (YES), that is, if acceleration has already started before the previous time, steps S24 to S30 are skipped and step S31 is executed. Is done.

  If it is determined in step S31 that the rotational speed of the electric supercharger 21 has not reached the target rotational speed (NO), the rotational speed of the electric supercharger 21 is predetermined toward the target rotational speed in step S33. It is raised (gradual increase) at an ascending speed. Thereafter, the process returns to step S21 (return). On the other hand, when it is determined that the rotational speed of the electric supercharger 21 has reached the target rotational speed (YES), the rotational speed of the electric supercharger 21 is held at the target rotational speed in step S32. Thereafter, the process returns to step S21 (return).

  If it is determined in step S22 that the engine DE or the vehicle is not in an accelerated state (NO), first, the acceleration flag F is reset to 0 in step S34. Subsequently, in step S35, the operation of the electric supercharger 21 is stopped, and the check valve 22 is opened simultaneously or slightly before this.

  Next, in step S36, the target oxygen concentration is determined based on the target oxygen concentration map using the engine speed and the accelerator opening as parameters. Subsequently, in step S37, various control values for realizing the target oxygen concentration are determined by the identification model DM. This step S37 corresponds to the aforementioned step S25. Thereafter, in step S38, the determined control value is output to the actual device. Thereafter, the process returns to step S21 (return).

  As described above, the engine DE or the vehicle turbocharger control according to the second embodiment of the present invention basically improves the acceleration of the engine DE or the vehicle as in the first embodiment. , Generation of wrinkles is suppressed or prevented.

1 is a schematic diagram showing a system configuration of a diesel engine according to the present invention. It is side surface sectional drawing of the turbine of the exhaust gas turbocharger of the engine shown in FIG. It is a block diagram which shows the structure of the control system of the engine shown in FIG. It is a block diagram which shows the structure of the intake model thru | or identification model used with the engine shown in FIG. It is a flowchart which shows the control procedure of the electric supercharger control of the engine which concerns on Embodiment 1 of this invention. It is a flowchart which shows the control procedure of the electric supercharger control of the engine which concerns on Embodiment 2 of this invention. It is a figure which shows the supply conditions of EGR gas which use an engine speed and an engine load as parameters. It is a figure which shows the transfer aspect of the driving | running state of the engine at the time of acceleration. It is a figure which shows the composition of the intake air before and behind acceleration.

Explanation of symbols

  DE diesel engine, C control unit, 1 intake valve, 2 intake port, 3 combustion chamber, 4 piston, 5 fuel injection valve, 6 exhaust valve, 7 exhaust port, 8 cylinder (cylinder), 9 connecting rod, 10 crankshaft, DESCRIPTION OF SYMBOLS 11 Engine starter, 12 Intake valve opening / closing cam mechanism, 13 Intake valve cam control apparatus, 14 Exhaust valve opening / closing cam mechanism, 15 Exhaust valve cam control apparatus, 16 Common intake passage, 16a First branch intake passage, 16b Second branch intake passage , 17 Air flow sensor, 18 Intake control valve, 19 Exhaust turbocharger, 19a Compressor, 19b Turbine, 20 Intercooler, 21 Electric supercharger, 21a Compressor, 21b Motor, 22 Check valve, 23 Surge tank, 24 Independent Intake passage, 25 Intake pressure sensor, 26 Common Air passage, 27 movable vane, 28 movable vane actuator, 29 second electric supercharger, 29a compressor, 29b motor, 30 exhaust gas purification catalyst, 31 particulate filter, 32 exhaust gas purification device, 33 first temperature sensor, 34 Second temperature sensor, 35 Exhaust valve, 36 High pressure EGR device, 37 High pressure EGR passage, 38 High pressure EGR cooler, 39 High pressure EGR control valve, 41 Low pressure EGR device, 42 Low pressure EGR passage, 43 Low pressure EGR cooler, 44 Low pressure EGR control Valve, 52 Turbine chamber, 53 Turbine blade, 54 Nozzle, 55 Movable vane shaft, 56 Engine speed sensor, 57 Crank angle sensor, 58 Engine water temperature sensor, 59 Accelerator opening sensor, 60 Intake air temperature sensor.

Claims (3)

An electric supercharger disposed in the intake passage;
An exhaust turbocharger,
An EGR passage that connects an intake passage upstream of the compressor of the exhaust turbocharger and an exhaust passage downstream of the turbine of the exhaust turbocharger to recirculate part of the exhaust gas in the exhaust passage to the intake passage. And an EGR device having an EGR valve disposed in the EGR passage,
EGR control means for controlling the exhaust gas recirculation amount via the EGR valve in accordance with the operating state of the engine;
The electric supercharger is operated at the time of acceleration, and when the engine operating state is in the EGR region, the electric supercharger that increases the operating rotational speed of the electric supercharger is higher than that in the non-EGR region. An engine supercharging device comprising: a charger control means. The EGR valve and the electric supercharger are controlled based on an intake model set based on at least the accelerator opening,
The above intake model is a virtual device that is set to have the same characteristics as the actual device that affects the actual intake state of the engine so that the same intake state as the actual engine intake state can be obtained. And a control value for the virtual device is determined based on a preset input parameter so that the actual engine intake state becomes the target intake state. The engine supercharging device according to claim 1.   The electric supercharger control means is configured to increase the number of pre-rotations of the electric supercharger when the engine operating state is in the EGR region during acceleration compared to when the engine is in the non-EGR region. The engine supercharging device according to claim 1, wherein the engine supercharging device is configured.

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