JP2004138077A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine with a simple configuration for excellently controlling the internal combustion engine when a throttle valve device is in an emergency. <P>SOLUTION: This control device comprises an abnormality detection means (S10) to detect abnormality of a throttle valve device based on the information (θTHT) of the operational quantity of an acceleration operating member of an internal combustion engine and an opening (θTH) of a throttle valve, a driving means (S12) to forcibly drive the throttle valve in a closing direction when abnormality is detected in the throttle valve device, an auxiliary intake means (S14) to introduce air of a predetermined volume into a combustion chamber of the internal combustion engine when the abnormality is detected, and a fuel control means (S16) to perform fuel cut of a predetermined cylinder according to the predetermined volume of air and the operational quantity (θTHT) of the acceleration operating member when the abnormality is detected. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a control device for an internal combustion engine, and more particularly, to a control device for an internal combustion engine that takes into account an abnormal condition of a throttle valve device.

In recent years, in gasoline engines mounted on vehicles, in order to reduce harmful exhaust gas components and improve fuel efficiency, etc., fuel is directly injected into an intake pipe injection type engine or combustion chamber designed to be able to operate at a lean air-fuel ratio. There have been proposed various in-cylinder injection-type engines which are configured to be capable of operating at a lean air-fuel ratio.
By the way, such a gasoline engine capable of operating at a lean air-fuel ratio requires more intake air than at the time of stoichiometric air-fuel ratio operation in order to make the air-fuel ratio lean. Therefore, conventionally, the increase in the intake air amount is corrected by providing a bypass passage that bypasses the throttle valve.

However, in this method, the corrected intake air amount is limited. Therefore, recently, a large-diameter intake passage area is used, and a throttle valve is electrically opened and closed using a motor. By adjusting the opening of the throttle valve, the above-described increase in the intake air amount can be corrected. A throttle valve device (electronic intake air amount control valve device) has been developed and put into practical use.
However, since such an electronic intake air amount control valve device uses an electric component such as a motor, there is a possibility that a failure such as a disconnection or a short circuit may occur due to deterioration over time or the like. When such a failure occurs, the electronic intake air amount control valve device no longer operates normally, that is, the operation becomes abnormal, and the operating state of the engine may be deteriorated.

Therefore, when an abnormality occurs in the electronic intake air amount control valve device, a fixed amount of intake air is taken through the bypass passage while closing the throttle valve, thereby preventing deterioration of the operating state of the engine while minimizing the deterioration. Discloses a throttle valve control device configured to enable the vehicle to travel. (See Patent Document 1)
Japanese Utility Model Laid-Open No. 1-28353

By the way, Patent Document 1 discloses that, when an abnormality occurs in the electronic intake air amount control valve device, a predetermined amount of intake is performed through a bypass passage, but engine control is performed in this situation. Nothing is said about it.
In recent years, vehicles are often driven at high speeds on highways or the like. In such a high-speed driving state, when an abnormality occurs in the electronic intake air amount control valve device, the driving safety of the vehicle is reduced. Therefore, it is desired to perform engine control so that the vehicle speed is not suddenly reduced.

Therefore, for example, a conventional cable cable is connected together with the electronic intake air amount control valve device, that is, the electronic control unit can manually open and close the throttle valve when an abnormality occurs in the electronic intake air amount control valve device. Accordingly, even when an abnormality occurs in the electronic intake air amount control valve device, the output torque of the engine can be adjusted in the same manner as when the electronic intake air amount control valve device is operating normally. Equipment is being developed.

However, providing a separate cable cord as described above is not preferable because it complicates the structure of the electronic intake air amount control valve device and leads to an increase in cost.
The present invention has been made in order to solve such a problem. An object of the present invention is to provide an internal combustion engine that has a simple configuration and enables good control of the internal combustion engine when the throttle valve device is abnormal. It is to provide a control device.

In order to achieve the above object, a control apparatus for an internal combustion engine according to claim 1 has a fuel injection valve for directly injecting fuel into each combustion chamber of a plurality of cylinders, and performs fuel injection in an intake stroke according to an operation state. A control device for an internal combustion engine capable of selecting an intake stroke injection mode for performing injection and a compression stroke injection mode for performing fuel injection in a compression stroke and capable of operating at a lean air-fuel ratio. Acceleration operation amount detection means for detecting the operation amount of the operation member, a motor driven based on a detection result of the acceleration operation amount detection means, and an opening / closing drive by the motor, which is disposed in an intake pipe of the internal combustion engine. A throttle valve device having a throttle valve, an abnormality detecting means for detecting an abnormality of the throttle valve device, and when the abnormality is detected by the abnormality detecting means, A drive unit for driving the throttle valve in a closing direction, an auxiliary intake unit capable of introducing a predetermined amount of air into a combustion chamber of the internal combustion engine when the abnormality is detected by the abnormality detection unit, and an abnormality detection unit. When the abnormality is detected, a mode switching unit that switches to the compression stroke injection mode, and when the abnormality is detected by the abnormality detection unit, the predetermined amount of air and the detection result of the acceleration operation amount detection unit Fuel control means for controlling the output torque by performing a fuel cut of a predetermined cylinder among the plurality of cylinders in response to the fuel cut.

According to a second aspect of the present invention, there is provided a control apparatus for an internal combustion engine, which has a fuel injection valve for directly injecting fuel into each combustion chamber of a plurality of cylinders, and performs an intake stroke injection mode in which fuel is injected in an intake stroke according to an operation state. A control device for an internal combustion engine capable of selecting a compression stroke injection mode for performing fuel injection during a stroke and capable of operating at a lean air-fuel ratio, wherein an acceleration detecting an operation amount of an acceleration operation member for performing an acceleration operation of the internal combustion engine is performed. An operation amount detection unit, a motor driven based on a detection result of the acceleration operation amount detection unit, and a throttle valve device provided in an intake pipe of the internal combustion engine and having a throttle valve opened and closed by the motor. Abnormality detecting means for detecting an abnormality of the throttle valve device, and driving the throttle valve in a closing direction when the abnormality is detected by the abnormality detecting means. A drive unit, when the abnormality is detected by the abnormality detection unit, an auxiliary intake unit capable of introducing a predetermined amount of air into the combustion chamber of the internal combustion engine, and when the abnormality is detected by the abnormality detection unit, A mode switching unit that switches to the compression stroke injection mode; and, when the abnormality is detected by the abnormality detection unit, among the plurality of cylinders according to the predetermined amount of air and a detection result of the acceleration operation amount detection unit. Fuel control means for performing fuel cut of a predetermined cylinder and controlling a fuel injection amount supplied to each of the combustion chambers according to the fuel cut.

4. The control device for an internal combustion engine according to claim 3, wherein the fuel control means performs a fuel cut after reducing an output with an air-fuel ratio lean when the fuel cut of the predetermined cylinder is performed. It is characterized in that the air-fuel ratios of the cylinders other than the above are enriched, and thereafter the air-fuel ratio is made lean again.
In the control device for an internal combustion engine according to claim 4, the throttle valve device further includes a throttle opening degree detecting means for detecting an opening degree of the throttle valve, and the abnormality detecting means includes a detection result of the acceleration operation amount detecting means. The abnormality is detected based on a comparison with a detection result of the throttle opening detection means.

In the control device for an internal combustion engine according to claim 5, the driving means includes a current interrupting means for interrupting a driving current supplied to the motor, and the throttle valve when the driving current is interrupted by the current interrupting means. Urging means for urging in the closing direction.
7. The control device for an internal combustion engine according to claim 6, wherein the auxiliary intake means includes a bypass passage provided in the throttle valve device and bypassing the throttle valve, wherein the bypass is provided when the throttle valve is driven in a closing direction. It is characterized in that intake is performed through a passage.

The control device for an internal combustion engine according to claim 7, wherein the auxiliary intake means includes a fully closed position changing means for changing a fully closed position of the throttle valve to an open side by a predetermined amount from a closed position. I have.

According to the control device for an internal combustion engine of claim 1 of the present invention using the above means, in the control device for the direct injection type spark ignition type internal combustion engine, a failure occurs in the motor and the like, and abnormality in the throttle valve device is detected by abnormality detection means. Is detected, the throttle valve can be driven in the closing direction by the driving means without using the motor, the predetermined amount of air can be introduced into the combustion chamber of the internal combustion engine by the auxiliary intake means, and the compression is performed by the mode switching means. The output torque of the engine can be adjusted by switching to the stroke injection mode and performing fuel cut on some of the cylinders in accordance with the predetermined amount of air and the detection result of the acceleration operation amount detection means.

Therefore, when an abnormality is detected in the throttle valve device, a substantially constant amount of intake air is taken and the fuel injection amount can be suitably controlled in accordance with the operation amount of the acceleration operating member. In the internal combustion engine, since the fuel injection amount and the output torque are almost completely proportional in the compression stroke injection mode region, even if the intake air amount is substantially constant, the fuel cut of some cylinders is switched by switching to the compression stroke injection mode. By doing so, the output torque of the internal combustion engine can be easily adjusted in a wide adjustment range, and the operating state of the internal combustion engine can be favorably maintained. Thereby, when the internal combustion engine is mounted on the vehicle, relatively good drivability can be secured together with the traveling safety of the vehicle.

According to the control device of the internal combustion engine of the second aspect, in the control device of the direct injection type spark ignition type internal combustion engine, when a failure occurs in the motor or the like and abnormality is detected in the throttle valve device by abnormality detection means, the motor The driving means can drive the throttle valve in the closing direction, the auxiliary intake means can introduce a predetermined amount of air into the combustion chamber of the internal combustion engine, and the mode switching means switches to the compression stroke injection mode. Adjustment of engine output torque by performing fuel cut of some cylinders according to fixed amount of air and detection result of acceleration operation amount detection means and controlling fuel injection amount to each combustion chamber according to fuel cut The area can be expanded.

Therefore, when an abnormality is detected in the throttle valve device, a substantially constant amount of intake air is taken and the fuel injection amount can be suitably controlled in accordance with the operation amount of the acceleration operating member. In the internal combustion engine, the fuel injection amount and the output torque are almost completely proportional in the compression stroke injection mode region. Therefore, even if the intake air amount is substantially constant, the engine is switched to the compression stroke injection mode to cut fuel in some cylinders. By performing the increase / decrease control of the fuel injection amount, the output torque of the internal combustion engine can be easily and appropriately adjusted in a wide adjustment range, and the operation state of the internal combustion engine can be favorably maintained. Thus, when the internal combustion engine is mounted on the vehicle, relatively good drivability can be secured together with the traveling safety of the vehicle.

According to the control device for an internal combustion engine of the third aspect, even when the fuel cut is performed as the fuel control means, the output torque is gradually and smoothly changed by appropriately adjusting the air-fuel ratio, so that the output torque adjustment is good. Can be done.
According to the control apparatus for an internal combustion engine of the fourth aspect, it is possible to easily detect the abnormality of the throttle valve device based on the comparison between the detection result of the acceleration operation amount detection means and the detection result of the throttle opening detection means. .

According to the control device for the internal combustion engine of the fifth aspect, when abnormality of the throttle valve device is detected, the drive current supplied to the motor can be cut off by the current cutoff means to release the motor power, and the urging means The throttle valve can be easily driven in the closing direction and can be favorably driven.
According to the control device for the internal combustion engine of the sixth aspect, when an abnormality is detected in the throttle valve device and the throttle valve is driven in the closing direction, intake can be performed via the bypass passage. Therefore, when an abnormality is detected in the throttle valve device, a constant amount of intake air can always be secured while the throttle valve is closed, and the operation state of the internal combustion engine can be maintained in a good condition.

According to the control device for an internal combustion engine of claim 7, when an abnormality is detected in the throttle valve device, the throttle valve can be kept in a slightly opened state. Therefore, with a simple configuration using the throttle valve, when an abnormality is detected in the throttle valve device, a constant amount of intake air can always be secured, and the operating state of the internal combustion engine can be maintained in a good state.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing one embodiment of a control device for an internal combustion engine according to the present invention mounted on a vehicle. Hereinafter, the configuration of the control device for the internal combustion engine will be described with reference to FIG.
The engine 1 can perform fuel injection in the compression stroke (late injection mode) together with fuel injection in the intake stroke (first injection mode), and can burn at the lean air-fuel ratio, that is, the lean air-fuel ratio. , An in-cylinder in-line four-cylinder gasoline engine is applied. In the in-cylinder injection type engine 1, an intake device, an intake device, an EGR device (exhaust gas recirculation device) for performing exhaust gas recirculation (EGR), etc., are designed exclusively for in-cylinder injection, and the engine 1 is designed to be easy to use. It is said that operation at a rich air-fuel ratio, a stoichiometric air-fuel ratio (stoichiometric) AFS (AFS = 14.7), and a lean air-fuel ratio (lean air-fuel ratio) can be realized.

電磁 The cylinder head 2 of the engine 1 is also provided with an electromagnetic fuel injection valve 4 together with an ignition plug 3 for each cylinder, so that fuel is directly injected into the combustion chamber 5. On the top surface of the piston 7 slidably held by the cylinder 6, a hemispherical depression, that is, a cavity 8 is formed at a position where the fuel spray from the fuel injection valve 4 reaches in the latter half of the compression stroke. ing. The compression ratio of the engine 1 is set higher (for example, about 12) than that of the intake pipe injection type. A DOHC 4-valve valve mechanism is employed as a valve operating mechanism. An intake camshaft 11 and an exhaust camshaft 12 are rotatably provided above the cylinder head 2 to drive intake and exhaust valves 9 and 10, respectively. Supported.

An intake port 13 is formed in the cylinder head 2 so as to pass through between the camshafts 11 and 12 in a substantially upright direction. The reverse tumble flow, which is the reverse direction of the tumble flow, can be generated. On the other hand, the exhaust port 14 is formed in a substantially horizontal direction similarly to a normal engine, but a large-diameter exhaust gas recirculation port, that is, an EGR port 15 is branched obliquely downward.

符号 In the drawing, reference numeral 16 denotes a water temperature sensor for detecting the cooling water temperature Tw. Reference numeral 17 denotes a vane-type crank angle sensor that outputs a crank angle signal SGT at a predetermined crank position (for example, 5 ° BTDC and 75 ° BTDC) of each cylinder. The engine rotation speed Ne can be detected based on the following. Reference numeral 19 denotes an ignition coil that outputs a high voltage to the ignition plug 3. A camshaft that rotates at half the number of revolutions of the crankshaft is provided with a cylinder discrimination sensor (not shown) that outputs a cylinder discrimination signal SGC. It is identifiable whether or not it is.

An electronic intake air amount control valve device, that is, a drive-by-wire type throttle body (throttle valve device, hereinafter referred to as DBW-T / B) is connected to the intake port 13 via an intake manifold 21 having a surge tank 20. ), And an intake pipe 25 having an air flow sensor 32 and an air cleaner 22 are connected thereto.
The DBW-T / B 23 has a butterfly type throttle valve (throttle valve) 28 that is driven by a stepper motor 24 to open and close a flow path, and a throttle position sensor that detects the opening of the throttle valve 28, that is, the throttle opening θTH. A throttle opening detecting means (hereinafter referred to as TPS) 29 and an idle switch 30 for detecting a substantially fully closed state of the throttle valve 28 to recognize an idling state of the engine 1 are provided. Actually, the throttle voltage ETPS corresponding to the throttle opening is output from the TPS 29, and the throttle opening θTH is recognized based on the throttle voltage ETPS.

Note that the DBW-T / B23 requires a large amount of intake air for the in-cylinder injection type engine 1 in the latter lean mode, particularly when burning at a super lean air-fuel ratio. It is said to be bigger than.
The intake pipe 25 is provided with a limp home pipe (auxiliary intake means, bypass passage) 26 that can bypass the DBW-T / B 23 and intake air into the intake manifold 21. A linear solenoid type limp is provided in the pipe. A home valve 27 is provided.

リ ン The limp home valve 27 is configured to open when an abnormality such as a failure of the DBW-T / B23 occurs, which will be described later in detail. That is, when the DBW-T / B 23 is abnormal, even when the throttle valve 28 is closed, the limp home valve 27 is opened, so that a constant flow rate (predetermined amount) of intake air flows through the limp home pipe 26. It is possible.

The air flow sensor 32 detects the intake air amount Qa, and uses, for example, a Karman vortex flow sensor. In addition, the intake air amount Qa may be obtained from a boost pressure sensor attached to the surge tank 20 and from the intake pipe pressure detected by the boost pressure sensor.
On the other hand, an exhaust pipe 43 having a three-way catalyst 42 and a muffler (not shown) is connected to the exhaust port 14 via an exhaust manifold 41 to which an O ₂ sensor 40 is attached. The above-mentioned EGR port 15 is connected to the upstream of the intake manifold 21 via a large-diameter EGR pipe 44, and a stepper motor-type EGR valve 45 is provided in the pipeline.

The fuel tank 50 is installed at the rear of the vehicle (not shown). The fuel stored in the fuel tank 50 is sucked up by an electric low-pressure fuel pump 51 and sent to the engine 1 via a low-pressure feed pipe 52. The fuel pressure in the low pressure feed pipe 52 is regulated to a relatively low pressure (low fuel pressure) by a first fuel pressure regulator 54 interposed in the return pipe 53. The fuel supplied to the engine 1 is supplied to each fuel injection valve 4 via a high-pressure feed pipe 56 and a delivery pipe 57 by a high-pressure fuel pump 55 attached to the cylinder head 2.

The high-pressure fuel pump 55 is, for example, of a swash plate axial piston type, is driven by the exhaust-side camshaft 12 or the intake-side camshaft 11, and can generate a discharge pressure of 5 MPa to 7 MPa or more even when the engine 1 is idling. ing. The fuel pressure in the delivery pipe 57 is regulated to a relatively high pressure (high fuel pressure) by a second fuel pressure regulator 59 interposed in the return pipe 58.

中 In the drawing, reference numeral 60 denotes an electromagnetic fuel pressure switching valve attached to the second fuel pressure regulator 59. The fuel pressure switching valve 60 is capable of relieving fuel in the ON state, thereby reducing the fuel pressure in the delivery pipe 57 to a low fuel pressure. Reference numeral 61 denotes a return pipe for returning a part of the fuel used for lubrication and cooling of the high-pressure fuel pump 55 to the fuel tank 50.

An ECU (electronic control unit) including an input / output device, a storage device (ROM, RAM, BURAM, etc.) for storing control programs, control maps, and the like, a central processing unit (CPU), a timer counter, and the like is provided in a vehicle cabin. A control unit 70 is provided, and the ECU 70 performs comprehensive control of the engine 1.
The ECU 70 includes, in addition to the various sensors, an accelerator positioning sensor (acceleration operation amount detection means, hereinafter abbreviated as APS) which is connected to an accelerator pedal 74 and outputs an accelerator voltage EAPS according to the accelerator opening. ) 72 is connected, and information from these sensors and the like is input. Actually, when the accelerator voltage EAPS is output from the APS 72, the accelerator opening θACC is recognized based on the accelerator voltage EAPS.

Then, the ECU 70 determines the fuel injection mode, the fuel injection amount, the ignition timing, the introduction amount of the EGR gas, and the like based on the detection information, and determines the fuel injection valve 4, the ignition coil 19, the EGR valve 45, and the like. Drive control of the stepper motor 24, the limp home valve 27 and the like. Although not described, a number of switches and sensors (not shown) are connected to the input side of the ECU 70 in addition to the above-described sensors, while a warning light 76 and various devices (not shown) are provided on the output side. And the like are also connected. Note that the ECU 70 operates upon receiving power supply from the battery 80.

Hereinafter, basic combustion control contents of the engine 1 configured as described above will be briefly described here.
When the driver turns on the ignition key when the engine 1 is in the cold state, the ECU 70 turns on the low-pressure fuel pump 51 and the regulator bypass valve 60 to supply low fuel pressure fuel to the fuel injection valve 4.

When the driver operates the ignition key, the engine 1 is cranked by a cell motor (not shown), and at the same time, the ECU 70 starts combustion control. At this time, the ECU 70 selects the first-stage injection mode (that is, the intake stroke injection mode) and injects fuel so as to have a relatively rich air-fuel ratio.
When the start of the engine 1 is completed and the engine 1 starts the idling operation, the high-pressure fuel pump 55 starts the rated discharge operation, and the ECU 70 turns off the regulator bypass valve 60 to supply the high-pressure fuel to the fuel injection valve 4. Supply fuel. At this time, the required fuel injection amount is obtained from the discharge pressure of the high-pressure fuel pump 55 and the valve opening time of the fuel injection valve 4, that is, the fuel injection time.

Until the cooling water temperature Tw rises to a predetermined value, the ECU 70 selects the first injection mode and injects fuel so as to attain a rich air-fuel ratio as in the case of starting.
When the engine 1 is warmed up, the ECU 70 determines the target average effective pressure corresponding to the target output based on the accelerator opening information θACC based on the accelerator voltage EAPS from the APS 72 and the engine speed information Ne from the crank angle sensor 17. Calculate Pe. Actually, a map indicating the relationship between the accelerator opening information θACC and the engine rotation speed Ne is set in advance, and the target average effective pressure Pe is read from this map. At the same time, the volume efficiency Ev is calculated based on the intake air amount information Qa from the air flow sensor 32.

As described above, when the target average effective pressure Pe and the volumetric efficiency Ev are obtained, if the fuel injection mode is the late injection mode, the target A / F, the injection end timing Tend, Each combustion parameter such as the ignition timing Tig and the EGR amount Legr is set. On the other hand, in the case of the first injection mode, various combustion parameters are set based on the volume efficiency Ev. Here, the first-stage injection mode includes a first-stage lean mode, a stoichiometric feedback mode (hereinafter, referred to as an SF / B mode), and an open-loop mode (hereinafter, referred to as an O / L mode). There is a mode. These fuel injection modes are switched according to the engine speed Ne and the target average effective pressure Pe or the volumetric efficiency Ev based on a fuel injection mode setting map (not shown). Here, a detailed description of the switching is omitted.

When the target A / F, the fuel injection end timing Tend, the ignition timing Tig, the EGR amount Legr, and the like are set in this way, the fuel injection time Tinj is set based on the target A / F, and the fuel injection amount is reduced. It is determined. Then, a signal corresponding to the fuel injection time Tinj is supplied to the fuel injection valve 4, and an amount of fuel corresponding to the fuel injection time Tinj is injected from the fuel injection valve 4. At this time, a signal corresponding to the fuel injection end timing Tend is also supplied to the fuel injection valve 4 at the same time, whereby the fuel injection timing is determined.

Further, the ignition timing Tig signal is supplied to the ignition coil 19, and the EGR amount Legr signal is supplied to the EGR valve 45, so that optimal combustion control is performed.
Therefore, for example, when the engine 1 is in the low load range such as during idling or low-speed running, the fuel injection mode is set to the late lean mode, fuel injection is performed in the compression stroke, and the target average effective pressure Pe is set. The fuel injection amount is determined so as to be a lean target A / F (for example, A / F = about 30 to 40) based on the ignition timing, and the ignition timing Tig and the EGR amount Legr are also set based on the target average effective pressure Pe. , Good combustion control is performed.

Note that the combustion in the late lean mode will be described in more detail. In the in-cylinder injection type engine 1, the cavity 8 is formed on the upper surface of the piston 7 as described above. From this, the intake air flowing from the intake port 13 flows along the cavity 8 to form the above-mentioned reverse tumble flow, so that the mixture of the fuel injected from the fuel injection valve 4 and the intake air, that is, the fuel spray, Good aggregation in the vicinity of 3. As a result, a mixture near the stoichiometric air-fuel ratio AFS is always formed in a layer around the spark plug 3 at the time of ignition. Therefore, in the latter-stage injection mode, good ignitability is ensured even at a lean air-fuel ratio as a whole.

{Circle around (2)} When the engine 1 is in the middle load range, for example, when traveling at a constant speed, the fuel injection mode is set to the first lean mode or the SF / B mode. In the case of the first half lean mode, the fuel injection is performed in the intake stroke, and the fuel injection amount is determined such that the target A / F is relatively lean (for example, A / F = about 20 to 23) based on the volumetric efficiency Ev. Also, the ignition timing Tig and the EGR amount Legr are set based on the volumetric efficiency Ev, so that good combustion control is performed.

On the other hand, in the SF / B mode, fuel injection is also performed in the intake stroke, and the ignition timing Tig and the EGR amount Legr are set based on the volume efficiency Ev. In this case, the O ₂ sensor The air-fuel ratio feedback control is performed according to the output voltage of 40, and the target A / F is controlled so as to become the stoichiometric air-fuel ratio AFS.
By the way, referring to FIG. 2, the DBW-T / B 23, the limp home pipe 26, the limp home valve 27, and the ECU 70, that is, the configuration of the control device according to the present invention are shown in more detail. With reference to the description, a more detailed configuration of the control device according to the present invention will be described. Here, the description of the above-described components is omitted.

First, the DBW-T / B 23 will be described. A throttle valve shaft 28a is connected to the stepper motor 24 via a gear unit 24a, and the throttle valve 28 is connected to the throttle valve shaft 28a at the center. . Therefore, the throttle valve 28 is rotatable with the throttle valve shaft 28a around the axis of the throttle valve shaft 28a in accordance with the rotation of the stepper motor 24. A coil spring (driving means, biasing means) 28b is provided around the throttle valve shaft 28a on the opposite side of the gear unit 24a with respect to the throttle valve 28. The coil spring 28b functions to urge the throttle valve 28 to the valve closing side when a drive signal is not supplied to the stepper motor 24. Reference numeral 28c in the figure denotes a rotation stopper of the throttle valve 28 when the throttle valve 28 is operated to the valve closing side. The stopper 28c has a buffer member (a coil spring or the like) for reducing a shock. Is provided.

On the other hand, in addition to the engine control unit 70a that performs the main control of the engine 1 as described above, the ECU 70 has a DBW control unit 70b that controls the operation of the DBW-T / B 23, and disconnection of power supply to the DBW control unit 70b. And a DBW power supply relay 70c for performing the operation. Note that signals can be freely exchanged between the engine control unit 70a and the DBW control unit 70b.
As shown in the figure, both the engine control unit 70a and the DBW control unit 70b operate by receiving the power supply from the battery 80, but the power supply to the DBW control unit 70b is performed via the DBW power relay 70c. Is to be done.

An input side of the engine control unit 70a is connected to various sensors in addition to the TPS 29 and the APS 72. On the other hand, the DBW power relay 70c is connected to the output side in addition to the limp home valve 27, various driving units and the warning lamp 76.
The engine control unit 70a calculates the target throttle opening θTHT based on the input signals from the APS 72 and the crank angle sensor 17 as shown in the figure, and also, as described above, inputs from various sensors. Based on the signal, control of various driving units such as the fuel injection valve 4, the ignition coil 19, the EGR valve 45, and the correction of the target throttle opening θTHT are performed. Further, as also shown in the figure, abnormality processing control of the DBW-T / B 23 is performed. The abnormality processing control of the DBW-T / B 23 (DBW abnormality processing control) is performed based on DBW abnormality detection in the DBW control unit 70b described later, and will be described later in detail.

The input side of the DBW control unit 70b is connected to various sensors in addition to the TPS 29 and the APS 72 as described above, while the output side is connected to the stepper motor 24.
In the DBW controller 70b, throttle opening feedback control (throttle opening F / B control) is performed based on the target throttle opening θTHT calculated by the engine controller 70a and the throttle opening information θTH from the TPS 29. In addition to controlling the drive of the stepper motor 24, the abnormality of the DBW-T / B 23 is detected as described above.

Here, FIG. 3 shows a flowchart of a DBW abnormality processing control routine according to the present invention. Hereinafter, a control procedure of the DBW abnormality processing will be described with reference to FIGS.
In step S10 of FIG. 3, it is determined whether or not the absolute value of the difference between the target throttle opening θTHT and the throttle opening information θTH output from the TPS 29 is larger than a predetermined value X1 (| θTHT−θTH |> X1). . This determination is for determining whether the DBW-T / B23 has an abnormality. That is, it is determined whether the stepper motor 24 or the TPS 29 of the DBW-T / B 23 is operating abnormally due to disconnection, short circuit, or the like (abnormality detecting means).

Normally, if the stepper motor 24 and the TPS 29 of the DBW-T / B 23 are operating normally, the stepper motor 24 operates according to the target throttle opening θTHT based on the output signal from the APS 72 to open and close the throttle valve 28. Then, the output signal from the TPS 29, that is, the throttle opening θTH should be in accordance with the target throttle opening θTHT.

However, when a failure such as a disconnection or short circuit occurs in the stepper motor 24 or the TPS 29 and an abnormality occurs in the DBW-T / B 23, the absolute value of the difference between the throttle opening θTH and the target throttle opening θTHT is no longer the predetermined value X1. Disappears. Accordingly, in this step S10, the difference between the throttle opening θTH and the target throttle opening θTHT is monitored, whereby the abnormality of the stepper motor 24 and the TPS 29, that is, the abnormality of the DBW-T / B23 is determined. ing.

If the determination result of step S10 is true (Yes) and the absolute value of the difference between the throttle opening θTH and the target throttle opening θTHT is larger than a predetermined value X1 (| θTHT−θTH |> X1), DBW−T / B23 can be determined to be abnormal, and in this case, the process proceeds to step S12.
In step S12, during the operation of the normal engine 1, the signal supplied from the engine control unit 70a to the DBW power relay 70c is cut off, and the DBW power relay 70c is turned off. Therefore, power supply from the battery 80 to the DBW control unit 70b is cut off, and all control by the DBW control unit 70b is stopped.

に よ り Thereby, the supply of the drive signal from the DBW control unit 70b to the stepper motor 24 is stopped, and the stepper motor 24 is turned off (current interrupting means). When the stepper motor 24 is de-energized in this manner, the throttle valve 28 is urged toward the valve closing side by the urging force of the coil spring 28b, and therefore, the throttle valve 28 is closed.

That is, when there is an abnormality in the DBW-T / B 23, that is, in a situation where the throttle valve 28 does not operate normally, not only the operating state of the engine 1 deteriorates but also the running state of the vehicle becomes abnormal. Although there is a possibility that the throttle valve 28 will be stable, such a problem is favorably prevented by closing the throttle valve 28, that is, returning the throttle valve 28 to the original position.

However, when the throttle valve 28 is closed, intake is hardly performed, that is, the operation of the engine 1 is substantially stopped. As described above, when the operation of the engine 1 is substantially stopped, the running state of the vehicle suddenly changes when the vehicle is running, which is not preferable.
Therefore, in the next step S14, the limp home valve 27 is opened, and the intake is performed via the limp home pipe 26 almost simultaneously with the closing of the throttle valve 28. As a result, when the DBW-T / B 23 has an abnormality, a certain amount of air is taken in through the limp home pipe 26 although not so much. That is, even if an abnormality occurs in the DBW-T / B 23 during traveling, traveling at the required minimum vehicle speed V1 is enabled. The vehicle speed V1 is set to, for example, 80 to 120 km / h in consideration of traveling on a highway. That is, the flow path area of the limp home pipe 26 is set so that at least the vehicle speed V1 (V1 = 80 to 120 km / h) can be secured.

By the way, when the intake is performed through the limp home pipe 26, the intake air amount Qa is limited to a constant amount, and it is necessary to set the fuel injection amount accordingly. The output torque of the engine 1 is obtained. However, in order to improve the traveling safety of the vehicle, it is desirable that the output torque can be variably controlled in the same manner as during normal traveling.

In this regard, in the in-cylinder injection engine 1, it is apparent from the fact that the target A / F for determining the fuel injection amount is set based on the target average effective pressure Pe when the fuel injection mode is the late lean mode. However, it is known that when the intake air amount Qa is constant, the output torque of the engine 1 is favorably proportional to the fuel injection amount as shown in FIG. This relationship is not limited to the case where the fuel injection mode is the late lean mode, but is also suitably applied to the case where the fuel injection mode is the early lean mode.

That is, in the in-cylinder injection type engine 1, in the late injection mode, the fuel is always collected around the ignition plug 3, ignited and burned, so that the output torque is adjusted according to the fuel injection amount. It is possible to change, and even if the air-fuel ratio is made leaner than in the lean mode in the previous term by reducing the fuel injection amount, the engine rotation fluctuation is less likely to occur, and the drivability is not deteriorated. Even when the engine 1 is performing lean combustion in the lean mode in the first half, fuel is always collected around the spark plug 3 by the action of the laminar flow in the combustion chamber 5, so that the fuel is similarly increased according to the fuel injection amount. The output torque can be changed.

Therefore, in the in-cylinder injection type engine 1, in the next step S15, for example, the fuel injection mode is forcibly set to the late lean mode or the early lean mode according to the vehicle speed V (mode switching means). In the next step S16, the fuel injection amount is calculated in accordance with the target throttle opening θTHT, that is, the output of the APS 72 based on the driver's depression amount of the accelerator pedal 74, and the fuel adjustment is performed based on this fuel injection amount. I'm trying to do it. Specifically, air-fuel ratio control is performed. As a result, even when the throttle valve 28 is deactivated due to an abnormality in the DBW-T / B 23, the output torque can be satisfactorily adjusted according to the operation of the accelerator pedal 74 by the driver, and the DBW-T / B 23 has an abnormality. The running safety of the vehicle at the time is ensured.

More specifically, here, the purpose is to adjust the output torque, and the cylinder for performing the fuel injection is selected to adjust the fuel injection amount. That is, the output torque of the engine 1 is adjusted by performing fuel cut of some cylinders (predetermined cylinders). Therefore, in step S16, the setting of the fuel cut cylinder is performed (fuel control means).
When the output torque is adjusted by the fuel cut, the output torque changes in a stepwise manner, and there is a possibility that a torque shock occurs. Therefore, the fuel injection injected from the fuel injection valve 4 according to the cylinder for which the fuel cut is performed. The amount is adjusted and the output torque is gradually changed (fuel control means). Specifically, the fuel cut is performed after the output is reduced with the air-fuel ratio being lean, and at this time, the air-fuel ratios of the cylinders other than the fuel-cut cylinder are enriched. As a result, when the fuel cut is performed, the output torque sharply decreases, but such a sharp decrease in the output torque is preferably prevented. After that, the air-fuel ratio is made lean again and the fuel control by adjusting the fuel injection amount is repeated. As a result, even when the fuel adjustment is performed by the fuel cut, the output torque can be satisfactorily adjusted by gradually and smoothly changing the output torque.

Then, in step S18, the warning light 76 is turned on to notify the driver that the DBW-T / B 23 has an abnormality and is performing the above-described series of processing.
If the result of the determination in step S10 is false (No) and the absolute value of the difference between the throttle opening θTH and the target throttle opening θTHT is equal to or smaller than a predetermined value X1 (| θTHT−θTH | ≦ X1), The DBW-T / B 23 can be determined to be normal. In this case, the process proceeds to step S20, where normal DBW control is performed. That is, in this case, the combustion control is properly performed as described above, and the stepper motor 24 is favorably controlled by the DBW control unit 70b.

As described above in detail, according to the control apparatus for an internal combustion engine of the present invention, the electronic intake air amount control valve device, that is, the drive-by-wire type throttle body (DBW-T / B) 23 is provided. When an abnormality occurs in the DBW-T / B 23, the throttle valve 28 is closed and the limp home valve 27 is opened, whereby the DBW-T / B 23 is opened via the limp home pipe 26. A certain amount of air is taken in such a way that the air is bypassed.

Therefore, when a failure occurs in the stepper motor 24, the TPS 29, or the like, and it is confirmed that the DBW-T / B 23 is in an abnormal state, the throttle valve 28 is closed to prevent the operating state of the engine 1 from deteriorating. At the same time, by performing a fixed amount of intake through the limp home pipe 26, the output torque of the engine 1 is more restricted than in the normal operation, but the stable operation state of the engine 1 can be maintained.

Further, according to the internal combustion engine control device of the present invention, since the engine 1 is an in-cylinder injection type internal combustion engine capable of operating at a lean air-fuel ratio, the fuel injection mode is set to the late lean mode or the early lean mode. By doing so, it is possible to adjust the fuel injection amount together with the fuel cut of some of the cylinders in accordance with the depression amount of the accelerator pedal 74 and adjust the output torque satisfactorily under a certain amount of intake air. Even if the DBW-T / B 23 is in an abnormal state during running, the running state of the vehicle can be suitably variably controlled in the same manner as in the normal running state. This makes it possible to secure relatively good drivability as well as traveling safety when the DBW-T / B23 is abnormal, without separately providing an accelerator cable as in the related art.

In the above-described embodiment, the engine 1 is an in-cylinder injection type internal combustion engine capable of operating at a lean air-fuel ratio. However, the engine 1 may be applied to a normal intake pipe injection type internal combustion engine. In this case, if the internal combustion engine is designed to be able to operate at a lean air-fuel ratio while being an intake pipe injection type, the fuel can be appropriately collected near the ignition plug by stratification of the air-fuel mixture. To adjust the output torque. On the other hand, when the combustible air-fuel ratio is narrow only in the vicinity of the stoichiometric air-fuel ratio AFS, such as in an internal combustion engine that is not designed for lean air-fuel ratio operation, and it is difficult to adjust the output torque by adjusting the fuel injection amount. Even in this case, the output torque can be adjusted by the fuel cut.

Further, in the above embodiment, when the DBW-T / B23 is abnormal, the limp home pipe 26 and the limp home valve 27 are used to bypass the DBW-T / B23 to perform a fixed amount of intake. However, the present invention is not limited to this. For example, an electromagnetic actuator is connected to the stopper 28c (see FIG. 2), and when an abnormality of the DBW-T / B23 is detected, a drive signal is supplied from the ECU 70 to the electromagnetic actuator. Then, the stopper 28c may be made to protrude (fully closed position changing means). Thus, even when the signal supply to the stepper motor 24 is stopped, the throttle valve 28 can be maintained in a slightly opened state without closing the throttle valve 28, and the amount of intake air when inhaling through the limp home pipe 26 is reduced. Approximately the same amount of intake is possible. Therefore, the same effect as in the above embodiment can be obtained.

In the above-described embodiment, the warning lamp 76 is turned on only when an abnormality occurs in the DBW-T / B 23, that is, the stepper motor 24, the TPS 29, and the like. A function of detecting an abnormality due to disconnection or short circuit of the lamp 27 may be provided, and the warning lamp 76 may be turned on when the abnormality of the limp home valve 27 is detected. This makes it possible to keep the limp home valve 27 always operable.

In the above embodiment, only one APS 72 is used, but a plurality of APSs 72 may be provided in consideration of the stability of detection accuracy.

1 is a schematic configuration diagram showing a direct injection spark ignition type internal combustion engine including a control device of the present invention. It is a schematic structure figure showing the control device of the present invention. It is a flowchart which shows the abnormality processing control routine at the time of abnormality of an electronic intake air amount control valve apparatus (DBW-T / B). 4 is a graph showing a relationship between a fuel injection amount and an output torque in a direct injection type spark ignition type internal combustion engine.

Explanation of reference numerals

1 engine (in-cylinder injection spark ignition internal combustion engine)
4 Fuel injection valve 23 DBW-T / B (Throttle valve device)
24 stepper motor 26 limp home pipe (auxiliary intake means, bypass passage)
27 Limp home valve 28 Throttle valve (throttle valve)
28a coil spring (driving means, biasing means)
28c Stopper 29 TPS (Throttle opening detection means)
70 Electronic Control Unit (ECU)
72 APS (acceleration operation amount detection means)
76 Warning Light

Claims (7)

An intake stroke injection mode in which fuel is directly injected into each combustion chamber of a plurality of cylinders and fuel is injected in an intake stroke according to an operation state, and a compression stroke injection mode in which fuel is injected in a compression stroke. And a lean air-fuel ratio operable internal combustion engine control device,
Acceleration operation amount detection means for detecting an operation amount of an acceleration operation member for performing an acceleration operation of the internal combustion engine,
A motor that is driven based on the detection result of the acceleration operation amount detection unit, and a throttle valve device that is disposed in an intake pipe of the internal combustion engine and has a throttle valve that is opened and closed by the motor.
Abnormality detection means for detecting an abnormality of the throttle valve device;
When the abnormality is detected by the abnormality detection unit, a driving unit that drives the throttle valve in a closing direction,
When the abnormality is detected by the abnormality detection unit, an auxiliary intake unit that can introduce a predetermined amount of air into a combustion chamber of the internal combustion engine;
A mode switching unit that switches to the compression stroke injection mode when the abnormality is detected by the abnormality detection unit;
When the abnormality is detected by the abnormality detecting means, an output torque is obtained by performing fuel cut of a predetermined cylinder among the plurality of cylinders according to the predetermined amount of air and a detection result of the acceleration operation amount detecting means. Controlling fuel control means;
A control device for an internal combustion engine, comprising: An intake stroke injection mode in which fuel is directly injected into each combustion chamber of a plurality of cylinders and fuel is injected in an intake stroke according to an operation state, and a compression stroke injection mode in which fuel is injected in a compression stroke. And a lean air-fuel ratio operable internal combustion engine control device,
Acceleration operation amount detection means for detecting an operation amount of an acceleration operation member for performing an acceleration operation of the internal combustion engine,
A motor that is driven based on the detection result of the acceleration operation amount detection unit, and a throttle valve device that is disposed in an intake pipe of the internal combustion engine and has a throttle valve that is opened and closed by the motor.
Abnormality detection means for detecting an abnormality of the throttle valve device;
When the abnormality is detected by the abnormality detection unit, a driving unit that drives the throttle valve in a closing direction,
When the abnormality is detected by the abnormality detection unit, an auxiliary intake unit that can introduce a predetermined amount of air into a combustion chamber of the internal combustion engine;
A mode switching unit that switches to the compression stroke injection mode when the abnormality is detected by the abnormality detection unit;
When the abnormality is detected by the abnormality detection means, a fuel cut of a predetermined cylinder among the plurality of cylinders is performed in accordance with the predetermined amount of air and a detection result of the acceleration operation amount detection means, and the fuel cut is performed. Fuel control means for controlling a fuel injection amount to be supplied to each of the combustion chambers,
A control device for an internal combustion engine, comprising: The fuel control means, when performing a fuel cut of the predetermined cylinder, performs a fuel cut after reducing the output as an air-fuel ratio lean, then, enrich the air-fuel ratio of the cylinders other than the fuel-cut cylinder, 3. The control device for an internal combustion engine according to claim 1, wherein the air-fuel ratio is made lean again. The throttle valve device further includes a throttle opening detection unit that detects an opening of the throttle valve,
4. The apparatus according to claim 1, wherein the abnormality detection unit detects the abnormality based on a comparison between a detection result of the acceleration operation amount detection unit and a detection result of the throttle opening detection unit. A control device for an internal combustion engine according to any of the preceding claims. The driving unit includes a current interrupting unit that interrupts a driving current supplied to the motor, and an urging unit that energizes the throttle valve in a closing direction when the driving current is interrupted by the current interrupting unit. The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the control device comprises: The auxiliary intake means is provided in the throttle valve device, includes a bypass passage that bypasses the throttle valve, and performs intake through the bypass passage when the throttle valve is driven in a closing direction. The control device for an internal combustion engine according to any one of claims 1 to 5, wherein The said auxiliary intake means includes a fully closed position changing means for changing the fully closed position of the throttle valve to the open side by a predetermined amount from the closed position, and further comprising: a fully closed position changing means. For internal combustion engine control.

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