JP2010127185A - Startup control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suitably suppress degradation in emission in startup of an internal combustion engine. <P>SOLUTION: In an engine system 10 having an engine 200 including an exhaust throttle valve 221 disposed upstream of a three-way catalyst 220 in an exhaust pipe 218, an ECU 100 performs a startup control. In the startup control, the cranking of the engine 200 is performed to increase exhaust pressure in an exhaust pressure increase section upstream of the exhaust throttle valve in the exhaust pipe 218, in a predetermined startup permission state where a throttle valve 210 is fully-opened, the exhaust throttle valve 221 is in fully-closed; an overlap amount between an intake valve 215 and an exhaust valve 216 is zero, and fuel injection is stopped. Fuel injection is started up when it is determined that the exhaust pressure in the exhaust pressure increase section is sufficiently increased and that oxygen concentration is sufficiently increased, and after-burning of unburnt HC is promoted. By the after-burning of the unburnt HC, the temperature elevation of the three-way catalyst 220 is promoted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a technical field of a vehicle start control device including an exhaust throttle valve and a variable valve operating device.

  As this type of device, a device for reducing the HC after starting by utilizing the increase in the exhaust gas temperature due to the increase in the exhaust pressure has been proposed (for example, see Patent Document 1). According to the engine temperature raising device disclosed in Patent Document 1 (hereinafter referred to as “prior art”), the fuel injection is stopped with the throttle valve opened and the exhaust throttle valve closed, and the exhaust temperature is reduced. The temperature raising operation M1 is performed until the catalyst activation temperature is reached. Here, the temperature raising operation M1 is a piston rising stroke in which the crankshaft is rotationally driven by the starter motor, the exhaust valve is opened in the expansion stroke, and the intake valve is opened in the intake stroke in which the piston is lowered. In the exhaust stroke and the compression stroke, both the intake and exhaust valves are closed. During the exhaust stroke, the working gas in the combustion chamber is compressed and heated, and the intake valve opens near the exhaust top dead center. The working gas is supplied to the intake passage so that the temperature of the intake system can be raised. In the subsequent intake stroke, the working gas in the intake passage is supplied again into the combustion chamber as the piston descends. Further, in the subsequent compression stroke, the working gas in the combustion chamber is compressed and heated, and the exhaust valve is near the compression top dead center. By opening, the hot working gas in the combustion chamber is supplied to the exhaust passage, and the exhaust system is heated.

  A technique has also been proposed in which the intake valve is continuously opened during cranking operation and the exhaust valve or exhaust throttle valve is continuously closed (see, for example, Patent Document 2).

  In addition, in a system that can manually operate a warm-up promoting device using an intake / exhaust throttle valve and idle-up, a system that operates the warm-up promoting device for a certain period after starting regardless of the state of the manual switch has been proposed ( For example, see Patent Document 3).

  Furthermore, there has been proposed one that closes the exhaust throttle valve during the period from the start of the engine to the first explosion (see, for example, Patent Document 4).

JP-A-2005-299408 JP 2007-182869 A Japanese Patent Laid-Open No. 11-148376 JP 2008-069667 A

  At the time of engine start, particularly at the time of cold start, since the engine temperature is low, the fuel vaporization efficiency is likely to decrease, and the fuel injection amount is increased, so that the combustion chamber becomes rich in the air-fuel ratio. Therefore, a relatively large amount of HC, which is a kind of unburned fuel component (hereinafter referred to as “unburned HC” as appropriate), tends to be discharged into the exhaust passage. On the other hand, a catalyst device is usually installed in the exhaust passage, and this type of unburned HC can be suitably purified in a temperature range higher than the catalyst activation temperature. If the temperature is not sufficiently high, the unburned HC may be discharged outside the vehicle without being purified by the catalyst device.

  In order to reliably purify this type of unburned HC when the engine is started, it is an effective measure to burn the unburned HC in the exhaust passage (so-called “afterburning”). In order to post-burn the unburned HC in the exhaust passage, the exhaust passage needs to be as hot as it is, but in addition to that, excess oxygen is required in the exhaust passage to promote the combustion reaction of the unburned HC. Become. However, as described above, at the time of start-up, the combustion chamber is rich in the air-fuel ratio, and the exhaust passage is necessarily rich in the air-fuel ratio. Therefore, if no measures are taken, sufficient oxygen does not exist in the exhaust passage when the engine is started, and it is difficult to avoid deterioration of emissions due to unburned HC.

  In response to such a problem, when the conventional technique is applied, the temperature of the exhaust passage can be suitably raised before the engine is started (before the fuel injection is started), so that the catalyst device can be raised quickly. However, since the working gas is returned from the exhaust passage to the combustion chamber in the compression stroke, the oxygen concentration in the essential exhaust passage does not increase at all. Therefore, it is difficult to burn the unburned HC in the exhaust passage, and the deterioration of emission is not necessarily suppressed sufficiently. That is, the conventional technique has a technical problem that the emission at the time of start-up may deteriorate due to the fact that unburned HC does not easily burn in the exhaust passage.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a vehicle start control device that can suitably suppress deterioration of emissions during start of an internal combustion engine.

  In order to solve the above-described problems, a vehicle start control device according to the present invention includes a fuel injection unit, an intake throttle valve installed in an intake passage, an exhaust throttle valve installed in an exhaust passage, an intake valve, and an exhaust valve. An internal combustion engine having a variable valve mechanism capable of changing a valve opening characteristic of at least one of the valves, cranking means capable of cranking the internal combustion engine, and a catalyst device installed in the exhaust passage And the intake throttle valve is configured such that the opening period of the intake valve does not overlap with the opening period of the exhaust valve when the internal combustion engine requests to start the internal combustion engine. Is opened, the exhaust throttle valve is closed, and fuel injection is stopped. The variable valve device, the intake throttle valve, the exhaust throttle valve, and the allowable At least some of the variable valve devices First control means for controlling, second control means for controlling the cranking means so that the cranking is performed in the start permission state, and cranking in the start permission state is continued for a predetermined first period. And a third control means for controlling the fuel injection means so that the fuel injection is started, and when a predetermined second period has elapsed after the internal combustion engine is started by the fuel injection. And fourth control means for controlling the exhaust throttle valve to control the exhaust throttle valve.

  According to the vehicle control device of the present invention, when the internal combustion engine is requested to start (for example, as a preferred embodiment, when various ignition switches are artificially operated when the vehicle is stopped, or the internal combustion engine is This refers to a case where some control condition that is to be started is satisfied, in which the latter includes, for example, an electric travel mode in a hybrid vehicle that includes various electric motors such as a motor generator in addition to an internal combustion engine as a power source. In addition, a case in which a condition for starting the internal combustion engine is satisfied during traveling in a similar traveling mode is included), for example, an ECU (Electronic Control Unit) or the like so as to enter a predetermined start permission state. The first configuration configured as various computer systems such as various processing units, various controllers or microcomputer devices The control means, the variable valve system, intake throttle valve, at least a portion is directly or indirectly controlled in the exhaust throttle valve and the fuel injection means.

  The “start permission state” according to the present invention means that at least (1) the opening period of the intake valve does not overlap with the opening period of the exhaust valve (that is, for each cylinder, the intake valve and / or the exhaust valve is opened). (2) The intake throttle valve installed in the intake passage (as a preferred form, a so-called throttle valve). ) Is opened, (3) the exhaust throttle valve installed in the exhaust passage is closed, and (4) one state of the internal combustion engine in which fuel injection is stopped. There may be various modes for the process until the internal combustion engine converges to the start permission state at the time of the start request. For example, when each part that defines the start permission state is not in a state corresponding to the start permission state at the time of the start request, all these operation states may be controlled at the time of the start request (however, the start request Since this occurs only when the engine is stopped, at least the fuel injection is stopped with a high probability at the time of the start request). There may be no control over the. Further, the first control unit does not necessarily execute the control of each part with the start request as a trigger. For example, when the internal combustion engine is stopped, the internal combustion engine may be stopped in a start-permitted state in preparation for an upcoming start request. Further, the control of each unit in obtaining the start permission state does not necessarily have to be performed simultaneously or substantially simultaneously, and does not necessarily have to be sequentially executed sequentially along the time series.

  On the other hand, according to the vehicle start control device of the present invention, the cranking is performed in the start permission state by the second control means configured as various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device. The cranking means is controlled so as to be performed, and for example, the third control means configured as various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device, performs cranking in the start permission state. The fuel injection means is controlled so that the fuel injection is started after continuing for the predetermined first period (in addition, unless the engine is a compression self-ignition internal combustion engine such as a diesel engine, the ignition by various ignition devices is necessarily performed. Can accompany). Further, when a predetermined second period has elapsed after the internal combustion engine is started by the fuel injection by the fourth control means configured as various processing units such as ECU, various controllers or various computer systems such as a microcomputer device, etc. The exhaust throttle valve is opened.

  “Cranking” according to the present invention refers to supplying a driving force capable of forcibly rotating the engine output shaft of the internal combustion engine (preferably a crankshaft). Therefore, the “cranking means” is an engine that consumes at least energy resources that can be supplied regardless of the driving state of the engine output shaft (in short, electric energy supplied from an appropriate power source such as a battery). The concept encompasses a mechanism, device, system, or the like that can apply this type of driving force to the output shaft, and as a preferred embodiment, a starter device including a starter motor and a drive device that drives the starter motor. It can take a form. However, when the vehicle is a hybrid vehicle as described above, various electric motors that can function as a power source may have the function as the cranking means according to the present invention depending on the power transmission mode. .

  Here, the action of the second control means is to control the cranking means so that the cranking is “performed” in the start permission state, and the state where the internal combustion engine is cranked in the start permission state. As long as it is obtained, there is no substantial restriction on the timing of starting cranking itself. That is, the operation of the second control unit and the operation of the first control unit may be performed in a time region where at least a part overlaps in time series, even if one is before or after the other in time series. For example, cranking may be started on the premise that the start permission state has been obtained (since cranking involves consumption of the above energy resources, it is fundamental from the viewpoint of efficient consumption of energy resources. This is a desirable mode), or the exhaust throttle valve may be opened at the start of cranking, the intake throttle valve may be opened, or the valve overlap may be This is to the effect that the valve opening characteristics of the intake and exhaust valves may be set so as to occur.

  When cranking is performed in the start-up permitted state, fresh air is introduced in the intake stroke in the intake stroke (note that the opening of the intake throttle valve in the start-up permitted state is at least sufficient for practical use. It is desirable to determine in advance experimentally, empirically, theoretically, or based on simulation so that the fuel can be supplied into the combustion chamber, or the intake throttle valve is fully opened or similar open in the start-up permitted state. May be controlled at a time) through the intake passage into the cylinder. This sucked fresh air (ie, intake air) passes through the compression stroke and the expansion stroke and is discharged as it is into the exhaust passage in the exhaust stroke because the fuel injection is stopped. The valve opening timing of the exhaust valve is set so that the valve opening periods do not overlap, i.e., overlap does not occur, so that in the exhaust stroke, gas blows back into the cylinder or from the exhaust passage to the intake passage. In fact, all the fresh air present in the cylinder is theoretically discharged into the exhaust passage.

  On the other hand, the exhaust throttle valve installed in the exhaust passage is in a closed state, and no gas flow is formed downstream of the exhaust throttle valve at this time. Therefore, as long as cranking is continued in the start-permitted state, fresh air is constantly pushed into a section of the exhaust passage from the exhaust valve to the exhaust throttle valve, and the exhaust pressure in the section increases with time. At the same time, the gas density in the section increases with time. Hereinafter, this section will be appropriately referred to as an “exhaust pressure increase section”. Since the volume of the exhaust pressure increase section is determined, the oxygen concentration in the exhaust pressure increase section basically increases with the increase of the gas density even though the increase speed is variable. In addition, since the fresh air is heated during the compression stroke and can be heated even when it is compressed and filled in the exhaust pressure increase section, the temperature of the gas filled in the exhaust pressure increase section (substantially fresh air) is It is higher than when natural intake is performed.

  Here, at the time of the start request, particularly at the time of the cold start request, the temperatures of the intake passage and the combustion chamber are lower than those after the warm-up is completed. Therefore, whether the fuel is injected into the intake passage such as an intake port or directly into the combustion chamber, the atomization of the fuel tends to be hindered. Therefore, when fuel injection is started by the third control means, the exhaust gas containing a relatively large amount of unburned HC (that is, the exhaust gas rich in the air-fuel ratio) is discharged from the exhaust passage in the initial stage including the initial explosion. It will flow into the pressure rise zone.

  On the other hand, at the stage where fuel injection is started by the third control means and the internal combustion engine is started (first explosion), the exhaust throttle valve is still closed by the fourth control means. During the period in which the exhaust throttle valve is closed after the internal combustion engine is started, the exhaust is not discharged at least outside the vehicle. That is, the exhaust gas at the start of the start including immediately after the start containing a relatively large amount of unburned HC temporarily stays in the exhaust pressure increase section. As described above, there is clearly abundant oxygen in this exhaust pressure increase section, as compared with the case where cranking is not performed at least in the start permission state. Oxidative combustion of the fuel HC, that is, afterburning is promoted. Since afterburning of unburned HC leads to purification of exhaust, it contributes to suppression of deterioration of exhaust emission when the exhaust throttle valve is opened by the fourth control means.

  On the other hand, a catalyst device is installed in the exhaust passage. Therefore, regardless of whether the exhaust throttle valve is installed upstream or downstream of the catalyst device, the temperature increase of the catalyst device is promoted by the afterburning of the unburned HC. For this reason, in addition to the direct emission deterioration suppression effect, the third control unit and the fourth control unit can obtain an indirect emission deterioration suppression effect due to early activation of the catalyst device. For the purpose of achieving early activation of the catalytic device, the exhaust throttle valve is preferably installed on the downstream side of the catalytic device. That is, in this case, the catalyst device is installed in the exhaust pressure increase section, and the temperature rise of the catalyst device is favorably promoted before the afterburning of the unburned HC is started. A remarkable temperature rise effect by burning can be obtained. Further, in this case, since the volume of the exhaust pressure increase section is relatively large, it is relatively easy to hold a sufficient amount of oxygen that can be used for oxidative combustion of unburned HC in the exhaust pressure increase section. Become.

  As described above, according to the vehicle start control device of the present invention, the internal combustion engine is cranked in the start permission state, and it is possible to increase the exhaust pressure in the exhaust pressure increase section in the exhaust passage and store abundant oxygen. Therefore, when the afterburning of unburned HC is promoted during the start-up period of the internal combustion engine (a corresponding period including the start time) and the exhaust throttle valve is finally opened (as a preferred form, the start-up is completed) Deterioration of emissions that can be treated as a time point is suitably suppressed. That is, it is possible to suitably suppress the deterioration of emissions when starting the internal combustion engine.

  The first period relating to the operation of the third control means and the second period relating to the fourth control means are each of this kind, for example, experimentally, empirically, theoretically or based on simulations. It may be a suitable value that can be determined as appropriate so that the effect of suppressing the deterioration of emission can be obtained to some extent as compared with the case where control is not performed.

  For example, the first period is a period until the exhaust pressure in the exhaust pressure increase section rises to such an extent that it is estimated that an oxygen amount that can sufficiently generate afterburning of unburned HC is secured over a corresponding period. It may be set. Alternatively, for example, within a range in which an oxygen concentration that can sufficiently advance afterburning of unburned HC is ensured (for example, the air-fuel ratio of the exhaust passage after start-up is, for example, a lean air-fuel ratio of around A / F = 20 May be set as short as possible). Theoretically speaking, if the intake stroke and the exhaust stroke are performed even once by cranking in the start-permitted state, the exhaust pressure in the exhaust pressure increase section increases correspondingly, and the oxygen concentration increases. The first period defining the start timing can be set in a wide range of time. Further, the first period does not necessarily have to be defined as the time value itself, but may be alternatively defined by another physical quantity, control amount, index value, or the like that correlates with the exhaust pressure in the exhaust pressure increase section. .

  Similarly, the second period may be set as a period until the temperature of the catalyst device increases to such an extent that the originally expected exhaust purification performance is ensured. Further, the second period does not necessarily have to be defined as the time value itself, but depends on other physical quantity, control quantity, or index value that correlates with the degree of temperature rise of the catalyst device (that is, the degree of progress of warm-up). Alternatively, it may be defined.

  As described above, the present invention fills the exhaust pressure rising section, which is a part of the exhaust passage upstream of the exhaust throttle valve, with a gas containing a large amount of fresh air by cooperative control of the exhaust throttle valve and the variable valve operating device. In view of the fact that the technical idea of increasing the oxygen concentration in the section can be embodied, by making the section limited to an air-fuel ratio lean state, Even if the combustion chamber is inevitably rich in air-fuel ratio due to various factors that occur during start-up, such as atomization inhibition, it is possible to suitably oxidize and burn unburned HC in the exhaust gas and to quickly raise the temperature of the catalyst device It provides extremely high profits in practice.

  In one aspect of the vehicle start control device according to the present invention, the third control means determines that the engine speed of the internal combustion engine is a reference value when cranking in the start permission state is continued for the first period. The fuel injection is started when the above value is reached or when the integrated value of the intake air amount of the internal combustion engine is equal to or greater than a reference value.

  Both the engine speed and the integrated value of the intake air amount are indicators that can define the degree of increase in exhaust pressure in the exhaust pressure increase section (that is, the degree of increase in gas density and the degree of increase in oxygen concentration). It is suitable as a value, and by using these as a determination index, it is possible to optimize the timing of the start of fuel injection.

  In another aspect of the vehicle start control device according to the present invention, the first control means closes the exhaust throttle valve when a predetermined third period elapses after the cranking is started.

  According to this aspect, the exhaust throttle valve is open at the start of cranking. Here, at the start of cranking, residual gas reflecting the previous operating conditions of the internal combustion engine remains in the combustion chamber and the exhaust passage, and at least the oxygen concentration is reduced with respect to fresh air. . Therefore, the oxygen concentration in the exhaust passage can be further improved by opening the exhaust throttle valve for a while after the start of cranking (that is, until the third period elapses), and after the unburned HC It becomes possible to further promote burning.

  In this aspect, the third period may be set to a period from a start time of the cranking to a time when fresh air sucked by the cranking reaches the exhaust throttle valve.

  As described above, when the third period is set to a period from the start of cranking to the time when fresh air reaches the exhaust throttle valve, the remaining fuel is discharged as soon as possible while discharging almost all of the gas. This is preferable because it is possible to start the injection.

  In another aspect of the vehicle start control device according to the present invention, the valve opening period of the intake valve overlaps the valve opening period of the exhaust valve before or after the timing at which the fuel injection is started. It further comprises fifth control means for controlling the variable valve operating apparatus.

  According to this aspect, for example, the fifth control means configured as various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device opens and closes the intake and exhaust valve opening periods before and after the start of fuel injection. The valve opening timings of the intake valve and / or the exhaust valve are controlled so as to overlap.

  According to this aspect, the opening timing of the intake valve and / or the exhaust valve is set so that the overlap period is generated in the intake and exhaust valves before and after the start of fuel injection (preferably simultaneously or substantially simultaneously). Be controlled. For this reason, in the intake stroke, gas blowback from the combustion chamber or the exhaust system occurs, fuel atomization is promoted, and the combustion performance at the time of starting can be improved. Therefore, the amount of unburned HC generated can be reduced.

  Here, in particular, when the intake and exhaust valves are simply overlapped, a sufficient negative pressure is not generated in the intake passage in the extremely low rotation region (for example, around 100 rpm) as in the starting. For this reason, almost no gas blows back into the intake passage. However, according to the present invention, the exhaust throttle valve is closed and a high exhaust pressure is secured on the exhaust passage side. The pressure difference between the exhaust passages becomes large, and the gas is preferably blown back into the intake passage during the valve overlap period. In particular, when the exhaust throttle valve is installed on the downstream side of the catalyst device, the volume of the exhaust pressure increase section in which such a high exhaust pressure is ensured becomes sufficiently large, and thus the blowback effect becomes more remarkable. Further, in this case, even if the complete explosion state is not obtained in the first cycle of starting, the gas blow-back effect can be continued for a long period of time, which is more effective.

  In another aspect of the vehicle start control device according to the present invention, whether or not the second period has elapsed is determined based on whether the engine speed of the internal combustion engine, the integrated value of the intake air amount of the internal combustion engine, or the oxygen of the catalyst device. The fourth control means further opens the exhaust throttle valve when it is determined that the second period has elapsed, based on the storage capacity Cmax.

  According to this aspect, for example, based on the engine rotational speed, the intake air amount, or the oxygen storage capacity Cmax of the catalyst device by the determining means configured as various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device. It is determined whether or not the second period has elapsed. For example, when these are equal to or greater than a preset reference value, the fourth control means opens the exhaust throttle valve. The engine speed, the intake air amount, and the oxygen storage capacity Camx are suitable as index values for determining the warm-up state of the catalyst device. According to this aspect, it is relatively easy to set the second period to be optimal. Is possible.

  In another aspect of the vehicle start control device according to the present invention, the fourth control means is configured such that the magnitude of the oxygen storage capacity Cmax of the catalyst device corresponds to the magnitude of the opening degree or the valve opening speed in the initial stage of valve opening. The opening of the exhaust throttle valve is gradually changed to the valve opening side according to the oxygen storage capacity Cmax.

  The oxygen storage capacity Cmax of the catalytic device defines the progress rate of the oxidative combustion reaction of unburned HC in the catalytic device. That is, if the oxygen storage capacity Cmax is relatively small, the catalyst device is relatively deteriorated, the oxidation combustion reaction rate of unburned HC is relatively decreased, and if the oxygen storage capacity Cmax is relatively large. The catalytic device is relatively undegraded, and the oxidation combustion reaction rate of unburned HC is relatively increased. For this reason, the internal combustion engine can be started as early as possible without causing deterioration of emissions by controlling the initial opening or valve opening speed when the exhaust throttle valve is opened according to the oxygen storage capacity Cmax. Can be completed.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

<Embodiment of the Invention>
Hereinafter, an embodiment according to a vehicle start control device of the present invention will be described with reference to the drawings as appropriate.
<First Embodiment>
<Configuration of Embodiment>
First, the configuration of the engine system 10 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the engine system 10.

  In FIG. 1, an engine system 10 is mounted on a vehicle (not shown) and includes an ECU 100, an engine 200, and a starter 300.

  The ECU 100 is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM, and the like, and is configured to be able to control the operation of each part of the engine system 10. 1 is an example of a “vehicle start control device”. The ECU 100 is configured to be able to execute start-up control described later in accordance with a control program stored in the ROM. The ECU 100 is an integrated electronic device configured to function as an example of each of the “first control unit”, “second control unit”, “third control unit”, and “fourth control unit” according to the present invention. It is a control unit, and the operation | movement which concerns on these each means is comprised so that all may be performed by ECU100. However, the physical, mechanical, and electrical configurations of each of the units according to the present invention are not limited to this. For example, each of these units includes a plurality of ECUs, various processing units, various controllers, a microcomputer device, and the like. It may be configured as various computer systems.

  The engine 200 combusts the air-fuel mixture through an ignition operation by an ignition device 202 in which a part of an ignition plug (not shown) is exposed in a combustion chamber in the cylinder 201, and is generated in accordance with an explosion force caused by the combustion. 1 is an example of an “internal combustion engine” according to the present invention configured to convert a reciprocating motion of a piston 203 into a rotational motion of a crankshaft 205 via a connecting rod 204. In the vicinity of the crankshaft 205, a crank position sensor 206 for detecting a crank angle representing the rotation state of the crankshaft 205 is installed. The crank position sensor 206 is electrically connected to the ECU 100, and the ECU 100 grasps the position of the piston 203 based on the crank angle detected by the crank position sensor 206, and is used for controlling various operation timings of the engine 200. It is the composition to do. The ECU 100 is configured to be able to calculate the engine speed NE of the engine 200 by time-processing the crank angle detected by the crank position sensor 206.

  Hereinafter, a further detailed configuration of the engine 200 will be described together with its operation. In this embodiment, the engine 200 is an in-line four-cylinder engine, and originally four cylinders are arranged in series in a direction perpendicular to the paper surface in FIG. 1, but the paper surface and the explanation are complicated. For the purpose of prevention, only one cylinder will be described here.

  In FIG. 1, the air sucked from the outside (that is, sucked air) is filtered by the air cleaner 208 in the process of passing through the intake pipe 207. A hot wire type air flow meter 209 is installed in the subsequent stage of the air cleaner 208, and is configured to be able to directly detect the mass flow rate of intake air (hereinafter referred to as “intake air amount” as appropriate). The air flow meter 209 is electrically connected to the ECU 100, and the detected intake air amount is referred to by the ECU 100 at a constant or indefinite timing.

  A throttle valve 210 capable of adjusting the amount of intake air flowing into the cylinder 201 in accordance with the open / closed state is disposed downstream of the air flow meter 209 in the intake pipe 207. The throttle valve 210 is an example of the “intake throttle valve” according to the present invention. The throttle opening, which is the opening of the throttle valve 210, is detected by the throttle position sensor 211 and is referred to at a constant or indefinite timing by the ECU 100 electrically connected to the throttle position sensor 211. Further, the throttle opening is variably controlled by a throttle valve motor 213 electrically connected to the ECU 100, and the throttle valve 210 constitutes a so-called electronically controlled throttle valve.

  The injector 214 is an electronically controlled fuel injection device that is an example of the “fuel injection means” according to the present invention and configured to be able to inject fuel into the intake port 213 that is continuous from the intake pipe 207. The fuel is stored in a fuel tank (not shown), and is pumped and supplied to the injector 214 via a delivery pipe (not shown) by the action of a low pressure pump (not shown). The injector 214 is electrically connected to the ECU 100, and is configured such that the fuel injection valve exposed to the intake port 213 is opened for the valve opening time corresponding to the energization time controlled by the ECU 100. The fuel injected from the injector 214 is mixed with the intake air at the intake port 213 to become the above-described mixture.

  The fuel injection means according to the present invention does not have to be a so-called intake port injector such as the injector 214. For example, the fuel pressure is increased by a high-pressure pump, and the fuel is directly injected into the high-temperature / high-pressure cylinder 201. You may have forms, such as what is called a direct injection injector comprised so that injection is possible.

  The communication state between the inside of the cylinder 201 and the intake port 213 is controlled by opening and closing the intake valve 215. The exhaust gas, which is the air-fuel mixture combusted inside the cylinder 201, passes through the exhaust valve 216 that opens and closes in conjunction with the opening and closing of the intake valve 215, and is discharged to the exhaust port 217. The exhaust port 217 communicates with the exhaust pipe 218, and the exhaust gas that has passed through the exhaust port 217 is discharged outside the vehicle via the exhaust pipe 218, the three-way catalyst 220 installed in the exhaust pipe 218, and the like.

  The three-way catalyst 220 reduces NOx contained in the exhaust of the engine 200, temporarily stores oxygen generated by the reduction of NOx, and oxidizes HC and CO contained in the exhaust by the stored oxygen. This is an example of the “catalyst device” according to the present invention configured to purify exhaust gas.

  On the other hand, the exhaust pipe 218 is provided with an air-fuel ratio sensor 219 capable of detecting an air-fuel ratio at the time of fuel combustion in the engine 200. The detected air-fuel ratio is electrically connected to the air-fuel ratio sensor 219. It is configured to be referred to by the connected ECU 100 at a constant or indefinite period. A water temperature sensor 223 for detecting the cooling water temperature of the engine 200 is disposed in the water jacket in the cylinder block that houses the cylinder 201. The water temperature sensor 223 is electrically connected to the ECU 100, and the detected coolant temperature of the engine 200 is referred to by the ECU 100 at a constant or indefinite period.

  Here, an exhaust throttle valve 221 is installed downstream of the three-way catalyst 220 in the exhaust pipe 218. The exhaust throttle valve 221 is configured to be openable and closable inside the exhaust pipe 218, and the open / close state is a fully open state in which the upstream and downstream of the exhaust throttle valve 218 are fully communicated (the opening degree corresponding to the fully open state is determined). 100 (%)) and the fully closed state in which the upstream and downstream communication of the exhaust throttle valve 218 is completely blocked (the opening degree corresponding to the fully closed state is 0 (%)). It is the composition which can be changed. The exhaust throttle valve 221 is electrically connected to the ECU 100, and has a configuration in which the opening degree changes according to the driving force supplied from the actuator 222 whose operation state is controlled by the ECU 100.

  Of the valve opening characteristics of the intake valve 215, the lift amount and the operating angle are basically the same as that of the intake cam 225 having an elliptical shape in cross section provided on the intake camshaft 224 that rotates in conjunction with the crankshaft 205. Determined by cam profile. In this embodiment, in particular, the relative rotational phase between the intake cam 225 and the intake camshaft 224 can be freely changed by an intake cam actuator 226 connected to the intake cam 225. The intake cam actuator 226 is an electric actuator that uses a power supply unit (not shown) as a power source, and is used to advance, retard, or fix the intake cam 225 relative to the intake cam shaft 224 relative to the intake cam 225. It is an example of the “variable valve operating device” according to the present invention, which is configured to be capable of applying the driving force of FIG.

  Therefore, in engine 200, the lift amount, operating angle, valve opening timing, and valve closing timing of intake valve 215 can be freely determined without any restriction on the cam profile of intake cam 225. The intake cam actuator 226 is electrically connected to the ECU 100, and the valve opening characteristics including the lift amount, the operating angle, the valve opening timing, and the valve closing timing in the intake valve 215 are determined via the intake cam actuator 226. It is the structure controlled by. Note that such a drive mechanism for controlling the valve opening characteristics of the intake valve 215 is an example of an electric cam drive mechanism called a so-called cam-by-wire.

  Of the valve opening characteristics of the exhaust valve 216, the lift amount and the operating angle are basically the same as that of the exhaust cam 228 having an elliptical shape in cross section provided rotatably on the exhaust camshaft 227 that rotates in conjunction with the crankshaft 205. Determined by cam profile. Here, in this embodiment, in particular, the relative rotational phase of the exhaust cam 228 and the exhaust camshaft 227 can be freely changed by the exhaust cam actuator 229 connected to the exhaust cam 228. The exhaust cam actuator 229 is an electric actuator that uses a power supply unit (not shown) as a power source, similar to the intake cam actuator 226, and advances the exhaust cam 228 relative to the exhaust cam shaft 227 relative to the exhaust cam 228. It is another example of the "variable valve operating apparatus" concerning this invention comprised so that the driving force for making an angle | corner, retardation, or fixing was possible.

  Therefore, in engine 200, the lift amount, operating angle, valve opening timing, and valve closing timing of exhaust valve 216 can be freely determined without any restriction on the cam profile of exhaust cam 228. The exhaust cam actuator 229 is electrically connected to the ECU 100, and the valve opening characteristics including the lift amount, the operating angle, the valve opening timing, and the valve closing timing of the exhaust valve 216 are determined via the exhaust cam actuator 229. It is the structure controlled by. Note that such a drive mechanism for controlling the valve opening characteristics of the exhaust valve 216 is an example of an electric cam drive mechanism called a so-called cam-by-wire.

  The mechanism for controlling the valve opening characteristics of the intake valve 215 and the exhaust valve 216 is not limited to the one described above. For example, a known electromagnetically driven valve or similar valve that opens and closes an intake valve 215 (hereinafter, unless otherwise specified, the exhaust valve 216 is also applicable) by electromagnetic force of an electromagnet such as a solenoid. A mechanism may be employed. In this case, for example, by variably controlling the electromagnetic force of the solenoid, the opening / closing characteristics such as the valve opening timing, the valve closing timing, the lift amount, the operating angle, and the opening / closing speed can be controlled freely and at high speed. Further, the intake valve 215 is configured so that a vane fixed to a vane rotor that is rotatably accommodated in a housing is appropriately advanced or retarded by hydraulic pressure of hydraulic oil applied to each of the advance chamber and the retard chamber. And the intake camshaft connected to the vane rotor is advanced or retarded relative to the crankshaft so that the valve timing of the intake valve 215 (that is, the valve opening timing and the valve closing timing described above are included). A known hydraulic valve mechanism such as VVT (Variable Valve Timing) that continuously changes the valve opening timing and the operating angle within the movable range of the vane rotor may be employed. However, when this type of hydraulic valve mechanism is adopted, the hydraulic pump that controls the hydraulic pressure of the hydraulic oil is an electric pump that can be driven regardless of the mechanical driving force that occurs as the engine 200 rotates. Is desirable.

  The starter 300 is a starter that is an example of the “cranking means” according to the present invention that is configured to be capable of cranking the engine 200. The starter 300 includes a starter motor connected to a flywheel connected to the crankshaft 205, an energization device capable of energizing the starter motor, and various gear devices that connect the starter motor and the flywheel. This is a known engine starting device. In the starter 300, the energization device is electrically connected to the ECU 100, and the operation state is controlled by the ECU 100.

<Operation of Embodiment>
In the engine system 10 according to the present embodiment, it is possible to start the engine 200 while suppressing the deterioration of the emission at the time of start-up by the start control executed by the ECU 100. Here, with reference to FIG. 2, the details of the start control will be described as the operation of the present embodiment. FIG. 2 is a flowchart of start control.

  In FIG. 2, the ECU 100 determines whether or not an ignition signal (IG in the figure) linked to the operation of an ignition key provided in the vehicle is in an on state (step S101). When the ignition signal is in an off state (step S101: NO), the starting process is temporarily terminated, and step S101 is executed again after a predetermined interval (this process is hereinafter referred to as “return process” as appropriate). And).

  When the ignition signal is in the on state (step S101: YES), the ECU 100 indicates that the start control completion flag XEXC that defines whether the start control is completed is “0” indicating that the start control is not completed. It is determined whether or not there is (step S102). When the start control completion flag XEXC is set to “1” that defines that the start control is completed (step S102: NO), the ECU 100 executes the return process described above. The case where the ignition signal is in the ON state is an example of “at the time of start request” according to the present invention.

  When the start control completion flag XEXC is set to “0” (step S102: YES), the ECU 100 fully opens the throttle valve 210 through the drive control of the throttle valve 212 (step S103). Note that the throttle valve 210 does not necessarily need to be fully opened, and has an intermediate state in which a sufficient amount of intake air is secured during cranking and the pumping loss due to the intake throttle is not manifested during cranking. May be. When the drive control of the throttle valve 210 is started, the ECU 100 next closes the exhaust throttle valve 221 through the drive control of the actuator 222 (step S104). Further, the ECU 100 sets the overlap amount OBL, which is the overlap amount of the valve opening period between the intake valve 215 and the exhaust valve 216, to zero (that is, through the drive control of the intake cam actuator 226 and the exhaust cam actuator 229) (that is, Control is performed so as not to overlap (step S105).

  Next, ECU 100 determines whether or not engine 200 is in a start-permitted state (step S106). Here, the start permission state means that fuel injection through the injector 214 is stopped, the throttle valve 210 is fully opened, the exhaust throttle valve 221 is fully closed, and the overlap amount OBL is zero. It refers to a certain state. That is, the start permission state according to step S106 is an example of the “start permission state” according to the present invention. Note that fuel injection through the injector 214 has already stopped at the time of execution of step S101. Here, the processing of step S103 to step S105 means starting control of the control target, and drive control of the throttle valve 210, the exhaust throttle valve 221, the intake cam actuator 226, and the exhaust cam actuator 229. Is appropriately performed as parallel processing. That is, in step S106, it is determined whether or not all these drive controls have been completed.

  When the start permission state is not obtained (step S106: NO), the ECU 100 waits for processing until the engine 200 shifts to the start permission state, and when the engine 200 shifts to the start permission state (step S106: YES), ECU 100 starts cranking of engine 200 through drive control of starter 300 (step S107). When the cranking is started, the ECU 100 determines whether or not the cranking time Tkr, which is an elapsed time from the cranking start time, exceeds the determination reference value A1 (step S108). While the cranking time Tkr does not reach the judgment reference value A1 (step S108: NO), the ECU 100 waits for the process in step S108, and when the cranking time Tkr reaches the judgment reference value A1 (step S108: YES). The ECU 100 starts fuel injection to the intake port 213 through the drive control of the injector 214 (step S109). That is, the determination reference value A1 is an example of a value that defines the “first period” according to the present invention.

  Here, when cranking is performed in the start permission state, the intake air sucked into the cylinder 201 through the intake valve 215 in the intake stroke is opened in the exhaust stroke through the compression stroke and the expansion stroke. It is discharged to the exhaust pipe 218 via the exhaust valve 216 in the valve state. At this time, since the overlap amount OBL of the intake / exhaust valve is controlled to be zero, no gas blows back from the inside of the cylinder 201 and the exhaust pipe 218 in the intake stroke, and almost all of the intake air inside the cylinder 201 is obtained. Is discharged to the exhaust pipe 218.

  On the other hand, the exhaust throttle valve 221 is fully closed, and the intake air discharged to the exhaust pipe 218 is blocked from flowing downstream from the exhaust throttle valve 221. For this reason, as the cranking is continued, a section upstream of the exhaust throttle valve 221 in the exhaust pipe 218 (that is, an example of the above-described exhaust pressure increasing section, and hereinafter referred to as “exhaust pressure increasing section” as appropriate). The exhaust pressure at is increased.

  The determination reference value A1 set for the cranking time Tkr is the time during which it is determined that the exhaust pressure in this exhaust pressure increase section has increased to such an extent that the afterburning process of unburned HC described later can be sufficiently induced. The value is previously determined experimentally, empirically, theoretically, or based on simulation.

  In the present embodiment, the “first period” according to the present invention is uniquely defined by the determination reference value A1, which is a fixed value. However, the first period is preferably defined by the exhaust pressure in the exhaust pressure increase section. In view of the points to be made, the first period may be defined by various index values of the engine 200 that define the degree of increase in the exhaust pressure. For example, it may be determined that the first period has elapsed when the engine speed NE in the cranking state has reached a reference value corresponding to the fact that the exhaust pressure has been achieved, or the air flow meter 209. A determination that the first period has elapsed may be made when the integrated value of the intake air amount detected by the above reaches a reference value corresponding to the fact that the exhaust pressure has been achieved.

  When the fuel injection is started, the ECU 100 determines whether or not the injection time Tinj, which is the elapsed time from the fuel injection start time, has exceeded the determination reference value B1 (step S110). When the injection time Tinj does not reach the determination reference value B1 (step S110: NO), the ECU 100 controls the process to a standby state, and when the injection time Tinj reaches the determination reference value B1 (step S110: YES), The ECU 100 controls the exhaust throttle valve 221 to a fully open state (step S111). That is, the determination reference value B1 is an example of a value that defines the “second period” according to the present invention.

  Here, when the exhaust pressure increases in the exhaust pressure increase section, the gas density in the exhaust pressure increase section increases. The gas filled in the exhaust pressure increase section is intake air that preferably contains oxygen, and when a sufficient exhaust pressure increase is obtained in the exhaust pressure increase section (that is, the cranking time reaches the judgment reference value A1). Abundant oxygen is present in the exhaust pressure increase section. Therefore, if fuel injection is continued while the exhaust throttle valve 221 is in the fully closed state, the combustion chamber becomes rich in the air-fuel ratio (because the fuel injection amount increase control at the start intervenes, etc.), whereas the exhaust gas is exhausted. The exhaust gas pressure increase section of the pipe 218 becomes the air-fuel ratio lean. In addition, since the intake air is in a pressurized state in the exhaust pressure increase section, its temperature is higher than the outside air.

  For this reason, in the exhaust pressure increase section, oxidation combustion of unburned HC discharged from the air-fuel ratio rich combustion chamber, so-called afterburning of unburned HC, is promoted. This afterburning of the unburned HC can continue for a sufficiently long period due to the fact that the exhaust pressure increase section is a section having a relatively large capacity including the three-way catalyst 220. For this reason, the temperature of the exhaust passage 218, particularly the exhaust pressure increase section, rapidly increases in a short time. At this time, the three-way catalyst 220 is installed in the exhaust pressure increase section, and as the temperature rises, the temperature increase of the three-way catalyst 220 is also promoted. As a result, the three-way catalyst 220 reaches its catalytic activation temperature region in a short period of time compared to the case where afterburning of unburned HC does not occur in this type of boost pressure increase section. That is, the warm-up of the three-way catalyst 220 is completed.

  The determination reference value B1 set for the injection time Tinj is a time value that can be determined in advance that the three-way catalyst 220 has reached the catalyst activation temperature region due to the afterburning of unburned HC in the exhaust pressure increase section. It is determined experimentally, empirically, theoretically or based on simulation.

  When the injection time Tinj reaches the judgment reference value B1 and the exhaust throttle valve 221 is fully opened, the ECU 100 sets the start control completion flag XEXC to “1” which means that the start control is completed (step) S112), a return process is executed. That is, after this, as long as the engine 200 is in an operating state, the determination branch related to step S102 is “NO”, so that the start control is not substantially effective. The starting control is performed as described above.

As described above, according to the start control according to the present embodiment, fuel injection is stopped, the throttle valve 210 is fully opened, the exhaust throttle valve 221 is fully closed, and the overlap of the intake and exhaust valves is zero. The engine 200 is cranked in the start permission state defined as the engine start state, and the engine 200 is started in a state where the oxygen concentration in the exhaust pressure increase section upstream of the exhaust throttle valve 221 in the exhaust pipe 218 is increased (that is, Fuel injection and accompanying ignition control) are executed. For this reason, it is possible to purify the exhaust gas by causing the unburned HC contained in the exhaust gas in a relatively large amount at the beginning of the start-up to burn after in the exhaust pressure increase section. Moreover, since the temperature increase of the three-way catalyst 220 installed in the exhaust pressure increase section can be promoted by the afterburning of the unburned HC, the three-way catalyst 220 can be brought into a catalytically active state at an early stage. At this time, the exhaust throttle valve 221 is opened when the three-way catalyst 220 has reached the catalyst active state, so that deterioration of the exhaust emission is suitably suppressed.
<Second Embodiment>
Next, the start control according to the second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a flowchart of the start control according to the second embodiment. In the figure, the same reference numerals are given to the same portions as those in FIG. 2, and the description thereof is omitted as appropriate.

  In FIG. 3, when the cranking time Tkr exceeds the judgment reference value A1, the ECU 100 increases the overlap amount of the intake and exhaust valves (step S201). When the overlap amount is increased, the ECU 100 starts fuel injection (step S109), and advances the process in the same manner as in the first embodiment.

  Here, the state in which the overlap amount of the intake / exhaust valve is enlarged, that is, the state in which the intake valve 215 is somewhat opened while the exhaust valve 216 is opened in the exhaust stroke (the previous overlap amount is zero). When the fuel injection is started in the above-mentioned manner, “expanding” means that a considerable amount of overlap is generated), the gas is blown back from the inside of the cylinder 201 and the exhaust pipe 218 in the exhaust stroke. Here, the gas staying in the exhaust pressure increase section is high in temperature with respect to the intake air, and the vaporization of the fuel in the intake port 213 is promoted by the blow-back of the gas. Therefore, the deterioration of emissions is further suppressed.

Here, in particular, almost no negative pressure is generated in the intake pipe 207 in the extremely low rotation region (for example, about 80 rpm) of the engine 200 as in cranking. Therefore, it is not possible to obtain the effect of returning the gas to the intake pipe 207 simply by providing an overlap of the intake and exhaust valves. On the other hand, in the present embodiment, the exhaust pressure in the exhaust pressure increase section is increased by the action of the exhaust throttle valve 221, and even if the intake pipe negative pressure is substantially equal to the atmospheric pressure, the pressure difference becomes sufficiently large, A gas blowback effect occurs. In other words, the effect of such enlargement of the overlap is remarkable when cranking is performed in the start permission state. Further, this blowback effect is constantly obtained for a period of time after the start of fuel injection due to the sufficiently large volume of the exhaust pressure increase section. Therefore, it is possible to reliably promote fuel vaporization.
<Third Embodiment>
Next, the start control according to the third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a flowchart of start control according to the third embodiment. In the figure, the same reference numerals are given to the same portions as those in FIG. 2, and the description thereof is omitted as appropriate.

  In FIG. 4, when fuel injection is started (step S109), the ECU 100 acquires the catalyst Cmax that is the oxygen storage capacity of the three-way catalyst 220 (step S301). Here, it is assumed that the catalyst Cmax is calculated before the engine 200 is stopped last time and stored in an appropriate storage area. Various known methods can be employed for calculating the catalyst Cmax, and details thereof are not mentioned here. For example, the catalyst Cmax intentionally sets the air-fuel ratio between the lean air-fuel ratio and the rich air-fuel ratio. It is calculated on the basis of the oxygen concentration of the exhaust pipe 218 when changed.

  When the catalyst Cmax is acquired, the ECU 100 acquires the warm-up determination time B2 (step S302). The warm-up determination time B2 is replaced with the determination reference value B1 according to the first embodiment, and is another example that defines the “second period” according to the present invention. Here, the warm-up determination time B2 will be described with reference to FIG. FIG. 5 is a schematic view illustrating the relationship between the warm-up determination time B2 and the catalyst Cmax.

  In FIG. 5, the warm-up determination time B2 is set as a decreasing function that decreases as the catalyst Cmax increases. When the catalyst Cmax is large, that is, when the oxygen storage capacity is large, the three-way catalyst 220 can store a relatively large amount of oxygen as an oxidant, and oxidative combustion of HC and CO compared to the case where the catalyst Cmax is small. Can be performed more suitably. Therefore, the catalyst Cmax affects the exhaust purification performance of the three-way catalyst 220 particularly in the inactive temperature region. That is, when the catalyst Cmax is large, it can be determined that the catalyst warm-up has been completed at a lower temperature side than when the catalyst Cmax is small (in a state where catalyst deterioration is progressing in short).

  Returning to FIG. 4, when the warm-up determination time B2 is acquired, the ECU 100 determines whether or not the injection time Tinj exceeds the warm-up determination time B2 (step S303). The ECU 100 maintains the exhaust throttle valve 221 in a fully closed state until the warm-up determination time B2 elapses, and when the injection time Tinj exceeds the warm-up determination time B2 (step S303: YES), the ECU 100 opens the exhaust throttle valve 221. Transition to the fully open state (step S304). At this time, the ECU 100 opens the exhaust throttle valve 221 according to a preset valve opening characteristic.

  Here, the valve opening characteristic of the exhaust throttle valve 221 will be described with reference to FIG. Here, FIG. 6 is a schematic view illustrating one opening characteristic of the exhaust throttle valve 221.

  6, the vertical axis represents the opening of the exhaust throttle valve 221 and the horizontal axis represents time, and FIG. 6 illustrates PRF_Cmax1 (solid line) as the valve opening characteristic when the catalyst Cmax is Cmax1. 2), and the illustrated PRF_Cmax2 (see chain line) as the valve opening characteristic when the catalyst Cmax is Cmax2 (Cmax2 <Cmax1).

  As shown in the figure, when opening of the exhaust throttle valve 221 is started at time T0, and when the catalyst Cmax is Cmax1, the opening of the exhaust throttle valve 221 is 100 (that is, fully opened) at time T1. When the catalyst Cmax is Cmax2, the opening degree of the exhaust throttle valve 221 becomes 100 at time T2 after time series from time T1. That is, as the catalyst Cmax is larger, the valve opening speed for opening the exhaust throttle valve 221 is set on the acceleration side. Since the catalyst Cmax is the oxygen storage capacity of the three-way catalyst 220 as described above, even if the exhaust throttle valve 221 is opened sharply when it is large, the catalyst Cmax of HC and CO Purification can be performed reliably.

Thus, according to the third embodiment, the valve opening timing and the valve opening speed of the exhaust throttle valve 221 are made variable and optimized in accordance with the catalyst Cmax of the three-way catalyst 220. For this reason, the engine 200 can be started as early as possible within a range in which the deterioration of the emission at the start is not made obvious.
<Fourth embodiment>
Next, the start control according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a flowchart of start control according to the fourth embodiment. In the figure, the same reference numerals are given to the same portions as those in FIG. 2, and the description thereof is omitted as appropriate.

  In FIG. 7, when the throttle valve 210 is controlled to be fully opened (step S103), the ECU 100 opens the exhaust throttle valve 221 (step S401). For example, if the exhaust throttle valve 221 is open when the engine 200 is stopped, step S401 may be skipped. Moreover, although the opening degree of the exhaust throttle valve 221 which concerns on step S401 is not specifically limited, suppose that it is a full open state here.

  The ECU 100 adjusts the overlap amount of the intake and exhaust valves while the exhaust throttle valve 221 is open (step S105), and starts cranking (step S107). That is, in the present embodiment, cranking is started before the engine 200 shifts to the start permission state described above.

  When cranking is started, ECU 100 determines whether or not cranking time Tkr exceeds determination reference value A2 (step S402). When the cranking time Tkr is less than or equal to the determination reference value A2 (step S402: NO), step S402 is repeatedly executed. When the cranking time Tkr exceeds the determination reference value A2 (step S402: YES), the ECU 100 performs exhaust. The throttle valve 221 is closed (step S104).

  Here, the determination reference value A2 is a value that can define the time during which it is determined that the intake air that has been sucked in at the start of cranking has reached the exhaust throttle valve 221. In addition, it is determined theoretically or based on simulation or the like. When the exhaust throttle valve 221 is closed and the start permission state is obtained (step S106: YES), the ECU 100 determines whether or not the cranking time Tkr exceeds the determination reference value A3 (step S403). When the cranking time Tkr is equal to or less than the determination reference value A3 (step S403: NO), step S403 is repeatedly executed, and when the cranking time Tkr exceeds the determination reference value A3 (step S403: YES), fuel injection is performed. Is started (step S109).

  As described above, in this embodiment, cranking of the engine 200 is started before shifting to the start permission state, and residual gas remaining in the intake pipe 207, the cylinder 201, and the exhaust pipe 218 before the start of cranking is discharged. In addition, the exhaust pressure increase section is filled with only air that has been newly sucked with the start of cranking. For this reason, the oxygen concentration in the exhaust pressure increase section can be increased earlier, and the starting period of the engine 200 can be shortened. Note that, in both the first embodiment and the fourth embodiment, the effect of promoting the afterburning of the unburned HC by increasing the oxygen concentration in the exhaust pressure increase section is obtained similarly. That is, as long as cranking is continued in a period in which engine 200 is in the start-permitted state, the cranking start timing is not greatly restricted.

  In the above-described various embodiments, the exhaust throttle valve 221 is installed downstream of the three-way catalyst 220 in the exhaust pipe 218, and the three-way catalyst 220 is included in the exhaust pressure increase section. However, the installation position of the exhaust throttle valve 221 is not limited to this, and may be upstream of the three-way catalyst 220.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. The apparatus is also included in the technical scope of the present invention.

1 is a schematic configuration diagram conceptually showing a configuration of an engine system according to a first embodiment of the present invention. It is a flowchart of the start control performed in the engine system of FIG. It is a flowchart of the starting control which concerns on 2nd Embodiment of this invention. It is a flowchart of the starting control which concerns on 3rd Embodiment of this invention. FIG. 5 is a schematic view illustrating the relationship between warm-up determination time and catalyst Cmax in connection with the start control in FIG. 4. FIG. 5 is a schematic view illustrating one opening characteristic of an exhaust throttle valve in connection with the start control of FIG. 4. It is a flowchart of the starting control which concerns on 4th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine system, 100 ... ECU, 200 ... Engine, 201 ... Cylinder, 210 ... Throttle valve, 215 ... Intake valve, 216 ... Exhaust valve, 220 ... Three-way catalyst, 221 ... Exhaust throttle valve, 226 ... Intake cam actuator 229 ... Exhaust cam actuator, 300 ... Starter.

Claims (7)

A fuel injection means, an intake throttle valve installed in the intake passage, an exhaust throttle valve installed in the exhaust passage, and a variable valve capable of changing a valve opening characteristic of at least one of the intake valve and the exhaust valve An internal combustion engine having a device;
Cranking means capable of cranking the internal combustion engine;
A vehicle start control device comprising: a catalyst device installed in the exhaust passage;
When the internal combustion engine requests to start the internal combustion engine, the valve opening period of the intake valve does not overlap with the valve opening period of the exhaust valve, the intake throttle valve is opened, and the exhaust throttle valve is closed. And a first control unit that controls at least a part of the variable valve device, the intake throttle valve, the exhaust throttle valve, and the variable valve device so as to be in a predetermined start permission state in which fuel injection is stopped. Control means;
Second control means for controlling the cranking means so that the cranking is performed in the start permission state;
Third control means for controlling the fuel injection means so that the fuel injection is started after cranking in the start-permitted state is continued for a predetermined first period;
And a fourth control means for controlling the exhaust throttle valve so that the valve is opened when a predetermined second period has elapsed after the internal combustion engine is started by the fuel injection. Start control device. The third control means integrates the intake air amount of the internal combustion engine when cranking in the start-permitted state is continued for the first period, when the engine speed of the internal combustion engine exceeds a reference value, or The vehicle start control device according to claim 1, wherein the fuel injection is started when the value becomes equal to or greater than a reference value. 3. The vehicle start control device according to claim 1, wherein the first control unit closes the exhaust throttle valve when a predetermined third period elapses after the cranking starts. 4. . The said 3rd period is set to the period from the start time of the said cranking to the time when the fresh air suck | inhaled by the said cranking reaches | attains the said exhaust throttle valve. Vehicle start control device. Fifth control means is further provided for controlling the variable valve operating apparatus so that the opening period of the intake valve overlaps with the opening period of the exhaust valve before or after the timing at which the fuel injection is started. The start control device for a vehicle according to any one of claims 1 to 4, wherein: A determination means for determining whether or not the second period has elapsed based on the engine rotational speed of the internal combustion engine, the integrated value of the intake air amount of the internal combustion engine, or the oxygen storage capacity Cmax of the catalyst device;
The vehicle according to any one of claims 1 to 5, wherein the fourth control means opens the exhaust throttle valve when it is determined that the second period has elapsed. Start control device. The fourth control means opens the exhaust throttle valve in accordance with the oxygen storage capacity Cmax so that the magnitude of the oxygen storage capacity Cmax of the catalyst device corresponds to the degree of opening or the opening speed at the initial valve opening. The vehicle start control device according to any one of claims 1 to 6, wherein the degree is gradually changed to the valve opening side.

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