JP5029490B2 - Start control device for internal combustion engine - Google Patents

Description

  The present invention relates to a technical field of a start control device for an internal combustion engine having variable valve operating means capable of changing a valve operating characteristic of an intake valve, such as VVT-i (Variable Valve Timing intelligent system: VVT-i).

  Various techniques for improving the fuel consumption of an internal combustion engine by devising the opening / closing operation of the intake valve by using this type of variable valve means have been proposed. For example, Patent Document 1 proposes a technique for driving a cam to a target position and phase amount when starting an engine equipped with an electric variable valve gear (VVT). Further, in Patent Document 2 and the like, after starting the engine, after determining the position and phase amount of the cam and crankshaft, the fuel injection timing and the fuel injection amount are set according to the position and phase amount. Proposed for technology. Further, in Patent Document 3 or Patent Document 4 or the like, when an electric VVT motor fails, hydraulic pressure is introduced into the VVT and locked to an intermediate state by a lock pin to improve engine startability. Proposed for technology. Further, Patent Document 5 and the like propose a technique for stabilizing the combustion state by increasing the fuel injection amount when the hydraulic VVT fails and then the engine operation state becomes the idle operation state. Has been.

JP 2006-125334 A Japanese translation of PCT publication No. 8-5069797 JP 2000-227010 A JP 2006-97580 A JP-A-4-362249

  However, according to the above-described Patent Document 1 or the like, when a failure occurs in the electric VVT, it becomes difficult to drive the VVT to a cam position or phase amount suitable for starting the engine. Technical problems arise. For this reason, when starting the engine, the air-fuel ratio becomes overlean or overrich, which causes a technical problem that engine startability deteriorates.

  Therefore, the present invention has been made in view of the above-described problems, for example, and an object of the present invention is to provide a start control device for an internal combustion engine that can start the internal combustion engine more quickly.

In order to solve the above-mentioned problem, the start control device for an internal combustion engine according to the present invention is a variable valve operating means capable of changing the phase amount corresponding to the opening / closing timing of the intake valve for performing intake into the combustion chamber of the internal combustion engine. An abnormality detecting means for detecting an operation abnormality of the variable valve means, a specifying means for specifying a phase amount of the variable valve means, an injection means for injecting fuel toward the combustion chamber , and the specified And changing means for changing the fuel injection amount to an increase side or a decrease side with respect to a reference amount according to the phase amount, and when the abnormal operation is detected at the start of the internal combustion engine, Instead of the fuel, it comprises control means for controlling the injection means so as to inject the fuel of the changed injection amount, and ignition means for igniting the fuel, and the control means is provided by the ignition means. When the fuel does not ignite The frequency of controlling the injection unit to inject the reference amount of the fuel is increased, and the injection unit is configured to inject the changed injection amount of the fuel instead of the reference amount of the fuel. Reduce the frequency of control .

  The “internal combustion engine” according to the present invention has one or a plurality of cylinders, and an air-fuel mixture that is a mixture of fuel such as gasoline, light oil or various alcohols and intake air in each of the cylinders. It is a concept that encompasses an engine that is configured to be able to take out the power generated when it burns, for example, through a mechanical transmission path such as a piston, a connecting rod, and a crankshaft, for example, This refers to a 2-cycle or 4-cycle reciprocating engine.

  The “variable valve operating means” according to the present invention can change the phase amount corresponding to the opening / closing timing of the intake valve that connects the combustion chamber of the internal combustion engine and the intake pipe at a predetermined timing. Here, the “phase amount” according to the present invention means an operation amount, a drive amount or an operation amount of the variable valve means that uniquely corresponds to the opening / closing timing of the intake valve, and is typically a variable valve means. Means the phase amount of the camshaft with respect to the crankshaft. For example, variable valve timing means such as VVT-i (VVT: Variable Valve Timing) may be driven by the power of an internal combustion engine such as a cam by wire mechanism, or may be driven by the power of an internal combustion engine such as an electromagnetic drive valve mechanism. May be driven without. The variable valve means may change the lift amount in addition to the above-described opening / closing timing of the intake valve by changing the phase amount.

  According to the internal combustion engine start control apparatus of the present invention, when an operation abnormality occurs in the variable valve means, the abnormality detection means detects the operation abnormality. The abnormal operation detected here means that the difference between the actual phase amount of the variable valve means and the phase amount of the variable valve means instructed by, for example, an ECU (Engine Control Unit) is larger than a predetermined threshold value. Means state. Typically, this abnormal operation is an open-side failure (i.e., a failure in which the intake valve shifts to the opening side as compared with normal operation or is fixed to the opening side for some reason), This may occur due to a failure on the closing side (that is, a failure in which the intake valve shifts to the closing side as compared with the normal operation or is fixed to the closing side for some reason).

  The phase amount of the variable valve operating means is specified by the specifying means. The “specific” according to the present invention typically means “specific” or “estimated” the magnitude of the phase amount directly or indirectly from the range of some physical quantity or parameter indicating the phase quantity of the variable valve means described above. "Means to do so. In addition to or instead of this, the specification according to the present invention refers to “detection” of the magnitude of the phase amount directly or indirectly from the range of some physical quantity or parameter indicating the phase quantity of the variable valve means described above. It means “detection”, “measurement”, and the like.

  The changing means changes the fuel injection amount to the increase side or the decrease side with respect to the reference amount in accordance with the specified phase amount. Here, the reference amount according to the present invention means the fuel injection amount when there is no abnormality in the variable valve means. Typically, the intake valve is at the bottom dead center (BDC: Bottom). This may mean the fuel injection amount that can achieve the ideal air-fuel ratio with respect to the amount of air taken in when the valve is closed at a position delayed by a crank angle of 70 degrees from the dead center.

  Under the control of the control means, when an abnormal operation of the variable valve means described above is detected at the start of the internal combustion engine, the injection means changes the fuel of the changed injection amount in place of the reference amount of fuel described above. Be injected.

  Thus, when an abnormal operation of the variable valve means described above is detected at the time of starting the internal combustion engine, at least according to the closing timing of the opening / closing timing of the intake valve corresponding to the phase amount of the specified variable valve means. Thus, the amount of air in the cylinder at the start of the internal combustion engine can be grasped quantitatively or qualitatively. As a result, the fuel is changed to the increase side or the decrease side with respect to the reference amount so that the air-fuel mixture in the cylinder combustion chamber approaches the ideal air-fuel ratio in accordance with the quantitatively or qualitatively determined air amount. It is possible to inject as much as the injection amount. As a result, when the internal combustion engine is started, the air-fuel ratio is made closer to the ideal air-fuel ratio while bringing the air-fuel ratio closer to the ideal air-fuel ratio while almost or completely eliminating the influence of the abnormal operation of the variable valve means. Since it is possible to effectively suppress a significant difference from the fuel ratio to the rich side or the lean side and to burn the fuel more reliably and appropriately, the internal combustion engine can be started more quickly.

  In one aspect of the start control device for an internal combustion engine according to the present invention, the engine further comprises first temperature detection means for detecting an engine temperature of the internal combustion engine, and the change means includes, in addition to the specified phase amount, According to the detected engine temperature, the fuel injection amount is changed to the increase side or the decrease side with respect to the reference amount.

  According to this aspect, for example, the engine temperature of the internal combustion engine is detected by the first temperature detecting means such as a temperature sensor provided in the intake pipe. Here, the “engine temperature of the internal combustion engine” is a comprehensive concept indicating a quantitative measure for directly or indirectly specifying the state of the fuel injected into the intake pipe or the combustion chamber. . Here, the fuel state may mean the degree or amount of evaporative fuel generated in the intake pipe or the combustion chamber, or the fuel state adheres to the wall surface of the intake pipe or the combustion chamber. It may mean the degree or amount of fuel attached. Therefore, the engine temperature of the internal combustion engine may be, for example, the temperature of the engine cooling water or the temperature of the cylinder outer wall. In practice, it is preferable to use output information detected by an existing temperature sensor, or a dedicated engine A temperature sensor may be provided.

  The changing means changes the fuel injection amount to the increase side or the decrease side with respect to the reference amount in accordance with the detected engine temperature in addition to the specified phase amount.

  Thereby, at the start of the internal combustion engine, in addition to almost or completely eliminating the influence of the abnormal operation of the variable valve means, while eliminating the influence of the evaporated fuel and the adhering fuel due to the engine temperature, The air-fuel ratio in the combustion chamber of the cylinder can be brought closer to the ideal air-fuel ratio, in other words, the air-fuel ratio can be effectively suppressed from being significantly separated from the ideal air-fuel ratio toward the rich side or the lean side.

  In another aspect of the start control apparatus for an internal combustion engine according to the present invention, the internal combustion engine further includes second temperature detection means for detecting an intake air temperature of the intake air sucked into the internal combustion engine, and the change means includes the specified phase change. In addition to the amount, the fuel injection amount is changed to the increase side or the decrease side with respect to the reference amount in accordance with the detected intake air temperature.

  According to this aspect, for example, the intake air temperature of the intake air sucked into the internal combustion engine is detected by the second temperature detection means such as a temperature sensor provided in the intake pipe. Here, “intake air temperature” is a comprehensive concept indicating a quantitative measure for directly or indirectly specifying the state of fuel injected into the intake pipe or combustion chamber and mixed with intake air. It is. Accordingly, the intake air temperature of the intake air sucked into the internal combustion engine may be, for example, the temperature of the outside of a vehicle equipped with the internal combustion engine (so-called outside air temperature), and in practice, the output detected by an existing temperature sensor. Information is preferably used, or a dedicated temperature sensor may be provided. The changing means changes the fuel injection amount to the increase side or the decrease side with respect to the reference amount in accordance with the detected intake air temperature in addition to the specified phase amount.

  As a result, at the start of the internal combustion engine, in addition to almost or completely eliminating the influence of the abnormal operation of the variable valve means, while substantially or completely eliminating the influence of the evaporated fuel and adhering fuel due to the intake air temperature, It is possible to bring the air-fuel mixture in the combustion chamber of the cylinder closer to the ideal air-fuel ratio. In other words, it is possible to effectively suppress the air-fuel ratio from significantly departing from the ideal air-fuel ratio to the rich side or the lean side.

  In the aspect according to the change means described above, a determination means that determines an allowable range of an air-fuel ratio that can start the internal combustion engine according to the detected intake air temperature in addition to or instead of the detected engine temperature. Determining means for determining whether or not to change the injection amount based on the determined allowable range of the air-fuel ratio in addition to or instead of the specified phase change amount, and the control means And when the determination means determines that the injection amount is to be changed, the injection means is controlled to inject the fuel with the changed injection amount instead of the reference amount of the fuel, and the determination When it is determined that the injection amount is not changed by the means, the injection means may be controlled to inject the reference amount of the fuel.

  According to this configuration, the determination means is configured to mix the air-fuel mixture in the combustion chamber of the cylinder based on the allowable range of the air-fuel ratio determined according to the engine temperature or the intake air temperature in addition to or instead of the specified phase change amount. In order to realize the ideal air-fuel ratio, it is determined whether or not to change the injection amount.

  As a result, the control process for changing the fuel injection amount can be omitted according to the determination result, so that the internal combustion engine can be started more quickly.

  In another aspect of the internal combustion engine start control apparatus according to the present invention, when the phase amount is specified by the specifying unit, the control unit replaces the fuel of the reference amount with the changed injection amount. The injection means is controlled to inject the fuel, and when the phase amount is not specified by the specifying means, the injection means is controlled to inject the reference amount of the fuel.

  According to this aspect, since the fuel injection amount is not changed unless the phase amount of the variable valve means is specified, it is effectively prevented that the air-fuel ratio of the air-fuel mixture in the combustion chamber of the cylinder varies due to an unexpected cause. be able to.

  In another aspect of the start control device for an internal combustion engine according to the present invention, the control device further includes ignition means for igniting the fuel, and the control means supplies the reference amount of the fuel when the fuel is not ignited by the ignition means. Increase the frequency of controlling the injection means to inject, and reduce the frequency of controlling the injection means to inject the changed injection amount of the fuel instead of the reference amount of the fuel .

  According to this aspect, when the fuel is not ignited by the ignition means and the influence of the unburned fuel is increased in the combustion chamber of the cylinder, the reference amount of fuel is increased and the reference amount of fuel is increased. Instead, the frequency with which the changed amount of fuel is injected is reduced. Thereby, it is possible to effectively prevent the air-fuel ratio of the air-fuel mixture in the combustion chamber of the cylinder from varying due to the influence of unburned fuel.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  Various preferred embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
(Basic configuration)
First, a basic configuration of an internal combustion engine start control apparatus according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view conceptually showing the basic structure and cross section of the start control device for the internal combustion engine according to the first embodiment.

  In FIG. 1, an internal combustion engine 200 mounted on a vehicle (not shown) is an example of a “variable valve device” that is an example of “variable valve means” according to the present invention, and an example of “specific means” according to the present invention. Phase amount measuring unit 10a, intake pipe 206, temperature sensor 220 as an example of the “first temperature detecting means” according to the present invention, throttle valve drive motor 217, combustion chamber 201, exhaust pipe 210, turbocharger (ie, A compressor 41 and a turbine 42), a temperature sensor 111a that measures an intake air temperature, which is an example of the “second temperature detecting means” according to the present invention, and a control device 100, which is an example of the “control means” according to the present invention. Configured.

  The intake pipe 206 is controlled to communicate with the combustion chamber 201 by opening and closing the intake valve 203. That is, in the intake pipe 206, air sucked from the outside (that is, sucked air) and fuel injected from the injector 211 that is a fuel injection device are mixed (that is, an air-fuel mixture is formed), and the intake valve 203 is mixed. Is supplied to the combustion chamber 201.

  The variable valve operating apparatus 10 is, for example, VVT-i, and can change the valve operating characteristics (for example, opening / closing timing or lift amount) of the intake valve 203 and the exhaust valve 204 using a cam-by-wire or an electromagnetically driven valve. It is configured.

  The variable valve gear 10 can change the phase amount corresponding to the opening / closing timing of the intake valve that connects the combustion chamber of the internal combustion engine and the intake pipe at a predetermined timing. Here, the “phase amount” according to this embodiment means an operation amount, a drive amount, or an operation amount of the variable valve apparatus 10 that uniquely corresponds to the opening / closing timing of the intake valve, and is typically a variable operation amount. It means the cam shaft phase amount relative to the crankshaft in the valve device 10. The variable valve operating apparatus 10 may be driven by the power of an internal combustion engine such as a Cam by Wire mechanism, or may be driven without the power of an internal combustion engine such as an electromagnetically driven valve mechanism. In addition, the variable valve apparatus 10 may change the lift amount in addition to the opening / closing timing of the intake valve described above.

  The phase amount of the variable valve apparatus 10 is measured by the phase amount measuring unit 10a.

  The accelerator position sensor 216 detects the amount of depression of the accelerator pedal 226 by the driver, that is, the accelerator opening. It is determined whether or not there is an acceleration request based on the accelerator opening.

  The temperature sensor 220 is disposed in the vicinity of the combustion chamber 201 from the intake pipe 206, for example, and detects the temperature of the internal combustion engine 200 from the water temperature of cooling water (not shown) that cools the internal combustion engine 200. Based on the detected temperature, the state of the fuel injected from the injector 211 (for example, how much it is evaporated) is specified directly or indirectly.

  The throttle valve drive motor 217 opens and closes the throttle valve 214 based on the depression amount. The throttle valve 214 adjusts the amount of air fed from the intake pipe 234 into the combustion chamber 201. The surge tank 111 distributes the air sent to each combustion chamber and has the effect of suppressing the pressure fluctuation of the distributed air. A temperature sensor 111a installed in the vicinity of the surge tank 111 measures the intake air temperature of the intake air sucked into the combustion chamber. The throttle position sensor 215 detects the opening degree of the throttle valve 214.

  The combustion chamber 201 is configured so that the air-fuel mixture sent from the intake pipe 206 inside can be burned by the spark plug 202. By this combustion, the piston 205 reciprocates up and down in the combustion chamber 201. The reciprocating motion is converted into the rotational motion of the crankshaft 219, and the vehicle on which the internal combustion engine 200 is mounted can be driven. The crank position sensor 218 detects the rotation angle (ie, crank angle) of the crankshaft 219.

  The exhaust pipe 210 is configured to be able to exhaust the exhaust gas generated inside the combustion chamber 201 via the exhaust valve 204. The air-fuel ratio sensor 221 is configured to detect the air-fuel ratio (so-called A / F) of the exhaust gas and transmit it to the control device 100. The air-fuel ratio detected in this way is used for feedback correction of the injection amount injected by the injector 211, for example.

  The turbocharger includes a compressor 41 and a turbine 42. The turbine 42 is disposed in the exhaust pipe 210, is rotated by receiving the kinetic energy of the exhaust gas, and is configured to be able to convert the rotational torque of the turbine 42 into the rotation of the compressor 41. The compressor 41 is disposed in the intake pipe 234 and can compress (supercharge) intake air by its rotation.

  The control device 100 controls the entire operation of the internal combustion engine 200. The control device 100 includes an intake valve control unit 110, an exhaust valve control unit 120, and the like, and controls the variable valve device 10 to open / close the intake valve 203, open / close the exhaust valve 204, and intake valve. The overlap amount during the opening period of 203 and the exhaust valve 204 is adjusted. In addition, the control apparatus 100 determines whether or not the difference between the actual phase amount of the variable valve apparatus 10 and the phase amount of the variable valve apparatus 10 instructed by the control apparatus 100 is greater than a predetermined threshold value. By determining, it has the function to detect the operation abnormality of the variable valve apparatus 10. Thereby, the control apparatus 100 may also constitute an example of an abnormality detection unit according to the present invention.

  The control device 100 (hereinafter referred to as “ECU 100” as appropriate) is preferably a well-known electronic control unit (ECU), a central processing unit (CPU), and a read storing a control program. It is configured as a logical operation circuit centered on a dedicated memory (Read Only Memory: ROM), an occasional writing / reading memory (Random Access Memory: RAM) for storing various data. Furthermore, an input port for receiving input signals from various sensors (for example, accelerator opening, throttle opening, rotational speed Ne of the internal combustion engine 200, crank angle CA, air-fuel ratio, etc.) and various actuators (for example, variable valve operating device) 10, the throttle valve drive motor 217, etc.) is connected via a bus to an output port that sends a control signal. A specific example of “changing means” according to the present invention is configured by a control device 100 including a memory in which a predetermined map described later is stored.

  According to the configuration described above, the control device for the internal combustion engine according to the present embodiment includes the temperature sensor 220, the temperature sensor 111a, the throttle valve drive motor 217, the variable valve device 10, the phase amount measurement unit 10a, and the control device 100. Etc.

  Thus, when the above-described abnormal operation of the variable valve apparatus 10 is detected at the start of the internal combustion engine, at least the closing timing of the opening / closing timing of the intake valve 203 corresponding to the specified phase amount of the variable valve apparatus 10 is closed. Depending on the timing, the amount of air in the cylinder at the start of the internal combustion engine can be grasped quantitatively or qualitatively. Incidentally, in order to change the fuel injection amount to the increase side or the decrease side with respect to the reference amount, the correlation between the correction coefficient multiplied by the reference amount and the closing timing of the intake valve will be described later. This will be described later with reference to FIGS. Accordingly, the fuel is increased or decreased with respect to the reference amount so that the air-fuel mixture in the combustion chamber 201 of the cylinder approaches the ideal air-fuel ratio in accordance with the quantitatively or qualitatively determined air amount. It is possible to inject only by the amount of injection changed. As a result, when the internal combustion engine is started, the air-fuel ratio in the cylinder combustion chamber is brought closer to the ideal air-fuel ratio while almost or completely eliminating the influence of the abnormal operation of the variable valve apparatus 10, in other words, the air-fuel ratio is ideal. Since it is possible to effectively suppress the significant departure from the air-fuel ratio to the rich side or the lean side and to burn the fuel more reliably and appropriately, the internal combustion engine can be started more quickly.

(Operating principle)
Next, with reference to FIGS. 2 to 5, the operation principle of the internal combustion engine start control apparatus according to the first embodiment of the present invention will be described. FIG. 2 is a flowchart showing the flow of control processing of the control device 100 that performs overall control of the internal combustion engine according to the first embodiment of the present invention. The control process shown in FIG. 2 is repeatedly executed at a predetermined cycle by the control device 100 (or the ECU 100).

  As shown in FIG. 2, first, it is determined whether an abnormal operation has occurred in the variable valve apparatus 10 (hereinafter, referred to as “VVT10” as appropriate) under the control of the ECU 100 (step S101). ). Typically, this abnormal operation occurs due to, for example, deposit fuel adhering to the moving part of the VVT 10 or foreign matter mixed into the moving part of the VVT 10, or the moving part of the VVT 10 is fixed. Or may occur.

  Next, under the control of the ECU 100, the phase amount measuring unit 10a measures the phase amount of the VVT 10 in which the operation abnormality has occurred and the movable unit is fixed (step S102). The valve closing timing of the intake valve can be quantitatively grasped from the measured phase amount. Specifically, the valve closing timing of the intake valve can be quantitatively grasped by the crank angle from the valve timing chart shown in FIG. 4 described later.

  Next, under the control of the ECU 100, the fuel reference amount is multiplied by a correction coefficient in order to change the fuel injection amount to the increase side or the decrease side with respect to the reference amount according to the measured phase amount. (Step S103). Here, the reference amount according to the present embodiment means the fuel injection amount when there is no operation abnormality in the VVT 10, and typically, the intake valve is at the bottom dead center (BDC: Bottom Dead Center). This may mean the fuel injection amount that can achieve the ideal air-fuel ratio with respect to the amount of air taken in when the valve is closed at a position that is delayed by a crank angle of 70 degrees. In addition, under the control of the ECU 100, fuel is injected by the injector 211 by the injection amount multiplied by the correction coefficient, and ignition is performed at a predetermined timing by the spark plug 202, and the internal combustion engine is started.

(Correlation between the correction coefficient multiplied by the fuel reference amount and the closing timing of the intake valve)
Next, with reference to FIGS. 3 to 5, the quantitative correlation between the correction coefficient to be multiplied by the reference amount of fuel and the closing timing of the intake valve according to the first embodiment will be described. FIG. 3 is a graph quantitatively showing the correlation between the intake air amount in the cylinder of the intake control device for the internal combustion engine according to the first embodiment and the closing timing of the intake valve. FIG. 4 shows one and other valve timing diagrams (FIGS. 4A and 4B) illustrating valve opening periods of the intake valve and the exhaust valve, respectively, in the intake control device for the internal combustion engine according to the first embodiment. ). FIG. 5 is a graph quantitatively showing the correlation between the correction coefficient multiplied by the reference amount of fuel and the closing timing of the intake valve in the intake control apparatus for the internal combustion engine according to the first embodiment.

  First, as shown in FIG. 3, according to a study by the inventors of the present application, the closing timing of the intake valve is retarded by a crank angle of 100 degrees from the BDC after the bottom dead center (BDC). When the internal combustion engine is started, the intake amount in the cylinder is the same as that in the cylinder when the internal combustion engine is started when the valve closing timing of the intake valve is delayed from the BDC by a crank angle of 70 degrees after the BDC. It has been found that it decreases to “0.55 times” based on the intake air amount. Note that the vertical axis in FIG. 3 indicates the weight percent when the weight of the intake air amount is 100 percent when the entire cylinder is inhaled. Thus, it has been found that the intake air amount decreases as the crank angle from the BDC increases, in other words, as the intake valve is closed late, after the closing timing of the intake valve is BDC.

  This is because, as shown in FIG. 4B, the intake air in the cylinder when the internal combustion engine is started when the closing timing of the intake valve is delayed by a crank angle of 100 degrees from BDC after BDC. As shown in FIG. 4A, the amount of intake air in the cylinder when the internal combustion engine is started when the closing timing of the intake valve is delayed by a crank angle of 70 degrees from BDC after BDC. This is because the air in the cylinder is pushed back to the intake pipe 206 by an amount corresponding to the hatched area in FIG.

  In the present embodiment, when the internal combustion engine is started, an abnormal operation occurs in the VVT 10, and even when the closing timing of the intake valve is different from a preset value (so-called default value), the phase amount of the VVT 10 By measuring this, it is possible to quantitatively grasp the closing timing of the intake valve. As a result, it is possible to quantitatively or qualitatively understand the amount of air in the cylinder when the internal combustion engine is started according to the closing timing of the intake valve. In particular, the predetermined map according to the first embodiment shows the amount of air in the combustion chamber of the cylinder with respect to the air amount quantitatively or qualitatively determined by the closing timing of the intake valve that uniquely corresponds to the phase amount of the VVT 10. A correction coefficient by which the reference amount of fuel is multiplied so that the air-fuel mixture approaches the ideal air-fuel ratio is defined. Specifically, as shown in FIG. 5, the correction coefficient can be uniquely defined from the closing timing of the intake valve. Typically, the correction coefficient for multiplying the reference amount of fuel when the internal combustion engine is started when the closing timing of the intake valve is delayed by a crank angle of 70 degrees from BDC after BDC is “1.0. The correction coefficient for multiplying the reference amount of fuel when the internal combustion engine is started when the closing timing of the intake valve is delayed from the BDC by a crank angle of 100 degrees after the BDC is “0.55”. It is. As described above, the correction coefficient also decreases in the same manner as the intake air amount decreases as the crank angle from the BDC increases after the valve closing timing of the intake valve increases after BDC, in other words, as the crank angle is delayed. Is defined. The reference amount is multiplied by a correction coefficient defined by the predetermined map, and fuel is injected by an injection amount that takes this correction coefficient into consideration.

  As a result, when the internal combustion engine is started, the fuel injection amount is corrected based on the predetermined map. Therefore, the air-fuel mixture in the combustion chamber of the cylinder is ideally empty while almost or completely eliminating the influence of the abnormal operation of the VVT 10. Since it is possible to effectively suppress the air-fuel ratio from approaching the ideal air-fuel ratio to the rich side or the lean side, and to burn the fuel more reliably and appropriately, the internal combustion engine can be It can be started more quickly.

(Second Embodiment)
Next, with reference to FIGS. 6 to 8, the operation principle of the start control device for the internal combustion engine according to the second embodiment of the present invention will be described. FIG. 6 is a flowchart showing the flow of control processing of the control device 100 that performs overall control of the internal combustion engine according to the second embodiment of the present invention. The control process shown in FIG. 6 is repeatedly executed by the ECU 100 at a predetermined cycle. Moreover, the same step number is attached | subjected to the control process substantially the same as the control process in 1st Embodiment demonstrated in FIG. 2 mentioned above, and those description is abbreviate | omitted suitably. FIG. 7 is a graph showing the engine temperature of the internal combustion engine start control apparatus according to the second embodiment of the present invention and the allowable range of air-fuel ratio at which the internal combustion engine can be started. FIG. 8 is a graph quantitatively showing the correlation between the correction coefficient multiplied by the reference amount of fuel and the closing timing of the intake valve in the intake control device for the internal combustion engine according to the second embodiment of the present invention. .

  As shown in FIG. 6, first, under the control of the ECU 100, the temperature sensor 220 measures the coolant temperature of the engine cooling water, and acquires the engine temperature of the internal combustion engine (step S201). In step S201, the intake air temperature may be measured by the temperature sensor 111a. In addition, acquisition according to the present embodiment means that measurement is performed by various sensors and stored in the storage device of the ECU 100.

  Next, through steps S101 to S102 described above, it is determined whether or not multiplication of a correction coefficient is necessary under the control of the ECU 100 (step S202). Specifically, as shown in FIG. 7, when an abnormal operation of the VVT 10 occurs, air that is quantitatively or qualitatively grasped by the closing timing of the intake valve that uniquely corresponds to the phase amount of the VVT 10 When the air-fuel ratio between the fuel amount and the reference amount of fuel is the value K1 and the engine temperature is the value T1, that is, the point P1 in FIG. 7), it is understood that there is no need to multiply the correction coefficient because it is within the allowable range of the air-fuel ratio. On the other hand, when the air-fuel ratio between the air amount and the fuel reference amount is the value K1 and the engine temperature is the value T2, the point P2 in FIG. 7 indicates the allowable range of the air-fuel ratio (in FIG. It can be seen that it is necessary to multiply the correction factor because it is outside (see hatched hatching). As indicated by R1 and R2 in FIG. 7, it has been found that the allowable range of the air-fuel ratio at which the internal combustion engine can be started becomes larger as the engine temperature becomes lower. . In addition, as indicated by L1 and L2 in FIG. 7, it has been found that the allowable range of the air-fuel ratio at which the internal combustion engine can be started becomes smaller as the engine temperature becomes lower. Yes.

  As described above, the engine temperature is attached to the state of the fuel injected into the intake pipe or the combustion chamber, that is, the degree and amount of evaporated fuel generated in the intake pipe or the combustion chamber, or the wall surface of the intake pipe or the combustion chamber. This affects the starting degree of the internal combustion engine with respect to the same air-fuel ratio.

  As a result of the determination in step S202 described above, when the multiplication of the correction coefficient is necessary (step S202: Yes), as described above, the fuel injection amount is set according to the measured phase amount under the control of the ECU 100. In order to change the reference amount to increase or decrease, the fuel reference amount is multiplied by a correction coefficient (step S103a). In particular, as shown in FIG. 8, the correction coefficient according to the second embodiment is defined according to the engine temperature level in the predetermined map according to the first embodiment described above with reference to FIG. You can do it. Specifically, the correction coefficient according to the second embodiment may be defined when the engine temperature is on the high temperature side (T-high) and when the engine temperature is on the low temperature side (T-low). . Note that FIG. 8 shows that as described above, as the engine temperature decreases, the allowable range on the rich side increases, that is, a larger amount of fuel may be injected, and the correction coefficient increases. Yes. In particular, the correlation between the correction coefficient for multiplying the fuel reference amount shown in FIG. 8 and the closing timing of the intake valve is an example, and it goes without saying that the present invention is not limited to this correlation.

(Third embodiment)
Next, with reference to FIG. 9, the operation principle of the start control device for the internal combustion engine according to the third embodiment of the present invention will be described. FIG. 9 is a flowchart showing the flow of control processing of the control device 100 that performs overall control of the internal combustion engine according to the third embodiment of the present invention. The control process shown in FIG. 9 is repeatedly executed by the ECU 100 at a predetermined cycle.

  As shown in FIG. 9, whether or not the phase amount of the VVT 10 to which the operation abnormality has occurred and the movable portion is fixed has been measured by the phase amount measurement unit 10a through the above-described steps S201 to S101 under the control of the ECU 100. Is determined (step S301). Here, when it is determined that the phase amount of the VVT 10 has been measured (step S301: Yes), as described above, under the control of the ECU 100, the fuel injection amount is set to the reference amount according to the measured phase amount. On the other hand, in order to change to the increase side or the decrease side, the fuel reference amount is multiplied by a correction coefficient (step S103). On the other hand, as a result of the determination in step S301, if it is not determined that the phase amount of the VVT 10 has been measured (step S301: No), the process returns to step S301 again to wait for the measurement of the phase amount.

  Thus, since the fuel injection amount is not changed unless the phase amount of the VVT 10 is measured, it is possible to effectively prevent the air-fuel ratio of the air-fuel mixture in the combustion chamber of the cylinder from varying due to an unexpected cause.

(Fourth embodiment)
Next, with reference to FIG. 10, the operation principle of the internal combustion engine start control apparatus according to the fourth embodiment of the present invention will be described. FIG. 10 is a flowchart showing the flow of control processing of the control device 100 that performs overall control of the internal combustion engine according to the fourth embodiment of the present invention. The control process shown in FIG. 10 is repeatedly executed by the ECU 100 at a predetermined cycle.

  As shown in FIG. 10, through the above-described step S201, under the control of the ECU 100, after a request for starting the internal combustion engine by the driver, rotation of the crankshaft, so-called cranking is started (step S401). In this cranking, in addition to the combustion in the cylinder of the internal combustion engine, the crankshaft may be rotated by the starter motor, or only the combustion in the cylinder of the internal combustion engine is attempted. Good.

  Next, through steps S101 and S301 described above, it is determined whether or not a predetermined time or more has elapsed after the start of cranking under the control of the ECU 100 (step S402). Here, the “predetermined time” according to the present embodiment is the amount of fuel attached to the combustion chamber of the cylinder generated by unburned fuel, or the amount of evaporated fuel in the combustion chamber generated by unburned fuel. Is a time determined in advance by empirical, experimental, theoretical, simulation, or the like as the time for changing the air fuel by a predetermined ratio or more.

  As a result of the determination in step S402, when it is determined that the predetermined time or more has not elapsed (step S402: No), as described above, fuel injection is performed according to the measured phase amount under the control of the ECU 100. In order to change the amount to increase or decrease with respect to the reference amount, the fuel reference amount is multiplied by a correction coefficient, fuel is injected, and ignition is performed (step S103a).

  Again, after the above-described steps S201, S401, S101, and S301, it is determined whether a predetermined time or more has elapsed after the start of cranking under the control of the ECU 100 (step S402). Here, when it is determined that the predetermined time or more has elapsed (step S402: Yes), the multiplication of the correction coefficient according to the present embodiment is omitted until the next start request, and the reference amount of fuel is injected. And ignition is performed (step S403).

  According to the fourth embodiment, when the fuel is not ignited by the spark plug 202 and the influence of the unburned fuel becomes large in the combustion chamber of the cylinder, the reference amount of fuel is increased and the reference amount is increased. Instead of this fuel, the frequency of injection of the fuel of the injection amount multiplied by the correction coefficient is decreased. Thereby, it is possible to effectively prevent the air-fuel ratio of the air-fuel mixture in the combustion chamber of the cylinder from varying due to the influence of unburned fuel.

(Examination of actions and effects according to this embodiment)
Next, with reference to FIG. 11, the effect | action and effect which concern on this embodiment are examined. FIG. 11 is a graph showing the correlation between the crank angle delayed in the closing timing of the intake valve and the operating state indicated by the load and the rotational speed according to the present embodiment.

  According to the study by the present inventor, as shown by the dotted line in FIG. 11, the internal combustion engine when the valve closing timing of the intake valve is delayed by a crank angle of 100 degrees from the BDC after the BDC is Compared to the case where the closing timing of the intake valve is delayed from the BDC by a crank angle of 70 degrees from the BDC (see the solid line in FIG. 11), the fuel consumption is improved in the driving state where the load is high and the rotation is high speed. It has been found that it can be improved.

  This is because the expansion ratio and the compression ratio are substantially equal in the Otto cycle, which is a general combustion cycle. Therefore, it is conceivable to increase the compression ratio (≈expansion ratio) when trying to increase the thermal efficiency. However, simply increasing the compression ratio may cause knocking. Therefore, a technique called an Atkinson cycle (or Miller cycle) is disclosed for the Otto cycle. In this Atkinson cycle, by taking a large expansion ratio and changing the closing timing of the intake valve 203, the substantial compression ratio is lowered, and knocking is prevented while increasing the thermal efficiency. Specifically, as shown in FIG. 4A and FIG. 4B, the substantial compression ratio can be lowered by delaying closing after the bottom dead center. In addition, the substantial compression ratio can be lowered by closing the intake valve earlier than the bottom dead center.

  Specifically, in order to improve the fuel efficiency, retarding the closing timing (or closing timing) of the intake valve in this way is to return the air once sucked back to the intake port side and the actual compression ratio. It is very preferable to improve pumping in reducing pump loss and cooling loss. More specifically, the actual compression ratio is improved by returning the intake air once sucked back to the intake side, and the pump loss can be reduced by an amount that does not require wasteful throttling by the throttle valve. Further, since the combustion gas once returns to the intake port side and the temperature in the cylinder decreases, the cooling loss can be reduced.

  However, when the intake valve is actually closed late, it is necessary to set the valve closing timing at the most retarded angle of intake air to 100 ° ABDC (After BDC), for example, and combustion deteriorates in the idle operation region as it is. However, the fluctuation of the combustion state becomes large. For this reason, it is preferable to slightly advance the cam timing of the intake valve in the idle operation region or the extremely light load operation region, and it is preferable to close the intake valve at a crank angle position of, for example, 70 ° ABDC. In other words, in general, when the closing timing of the intake valve is generally performed, a slight advance is made in the idling operation region or the extremely light load operation region from the start state, and then the intake valve is closed slowly during normal driving, thereby reducing the fuel consumption. It is generally performed to improve.

  However, when the variable valve operating device of the intake valve (so-called cam timing variable mechanism) itself fails and is stuck at a phase amount corresponding to the closing timing of either the late closing side or the early closing side, The reference phase amount that was originally set deviates from the intended true value, and the closing timing of the intake valve with respect to the reference phase amount at the time of failure and the intake valve's timing with respect to the intended reference phase amount There arises a technical problem that a difference amount is generated in the intake air amount sucked at the time of starting by the valve closing timing and the difference amount. For this reason, when the variable valve operating device is malfunctioning, if the same amount of fuel is injected as when it is not malfunctioning, it becomes over-rich or over-lean, and the air-fuel ratio at start-up varies significantly. There is a technical problem that the engine startability is adversely affected.

  In contrast, according to the present embodiment, when an abnormal operation of the variable valve device 10 described above is detected at the start of the internal combustion engine, the intake valve corresponding to the specified phase amount of the variable valve device 10 is detected. The amount of air in the cylinder at the start of the internal combustion engine can be grasped quantitatively or qualitatively according to at least the valve closing timing among the opening / closing timings 203. Accordingly, the fuel is increased or decreased with respect to the reference amount so that the air-fuel mixture in the combustion chamber 201 of the cylinder approaches the ideal air-fuel ratio in accordance with the quantitatively or qualitatively determined air amount. It is possible to inject only by the amount of injection changed. As a result, when the internal combustion engine is started, the air-fuel ratio in the cylinder combustion chamber is brought closer to the ideal air-fuel ratio while almost or completely eliminating the influence of the abnormal operation of the variable valve apparatus 10, in other words, the air-fuel ratio is ideal. Since it is possible to effectively suppress the significant departure from the air-fuel ratio to the rich side or the lean side and to burn the fuel more reliably and appropriately, the internal combustion engine can be started more quickly.

  Although the above embodiment has been described using a single internal combustion engine, other modes may be used as long as the engine has valve operating means capable of an Atkinson cycle. For example, when an Atkinson cycle is used in an internal combustion engine, the present invention can be applied to a hybrid system that can supplement the output with an electric motor.

  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 control device is also included in the technical scope of the present invention.

1 is a schematic cross-sectional view conceptually showing a basic configuration and a cross section of a start control device for an internal combustion engine according to a first embodiment. It is the flowchart which showed the flow of the control processing of the control apparatus 100 which controls the internal combustion engine which concerns on 1st Embodiment of this invention. It is a graph which shows quantitatively the correlation between the amount of intake in a cylinder of the intake control device of an internal-combustion engine concerning a 1st embodiment, and the valve closing timing of an intake valve. FIG. 6 is one and other valve timing diagrams (FIGS. 4A and 4B) illustrating valve opening periods of an intake valve and an exhaust valve, respectively, in the intake control device for an internal combustion engine according to the first embodiment. 4 is a graph quantitatively showing a correlation between a correction coefficient multiplied by a reference amount of fuel and a closing timing of the intake valve in the intake control device for the internal combustion engine according to the first embodiment. It is the flowchart which showed the flow of the control processing of the control apparatus 100 which performs overall control of the internal combustion engine which concerns on 2nd Embodiment of this invention. 6 is a graph showing an engine temperature of an internal combustion engine start control device according to a second embodiment of the present invention and an allowable range of an air-fuel ratio at which the internal combustion engine can be started. It is a graph which shows quantitatively the correlation of the correction coefficient by which the reference quantity of fuel is multiplied, and the closing timing of an intake valve in the intake control device of the internal-combustion engine concerning a 2nd embodiment of the present invention. It is the flowchart which showed the flow of the control processing of the control apparatus 100 which performs overall control of the internal combustion engine which concerns on 3rd Embodiment of this invention. It is the flowchart which showed the flow of the control processing of the control apparatus 100 which performs overall control of the internal combustion engine which concerns on 4th Embodiment of this invention. 4 is a graph showing a correlation between a crank angle delayed in the closing timing of the intake valve and an operation state indicated by a load and a rotational speed according to the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Variable valve apparatus, phase amount measurement part 10a, 100 ... Control apparatus, 111a ... Temperature sensor, 200 ... Internal combustion engine, 201 ... Combustion chamber, 206 ... Intake pipe, 210 ... Exhaust pipe, 211 ... Injector, 217 ... Throttle Valve drive motor, 220... Temperature sensor, air-fuel ratio sensor 221.

Claims (5)

Variable valve operating means capable of changing the phase amount corresponding to the opening / closing timing of the intake valve for performing intake into the combustion chamber of the internal combustion engine;
An abnormality detecting means for detecting an abnormal operation of the variable valve means;
Specifying means for specifying the phase amount of the variable valve means;
Injection means for injecting fuel toward the combustion chamber;
Change means for changing the fuel injection amount to an increase side or a decrease side with respect to a reference amount according to the specified phase amount;
Control means for controlling the injection means to inject the changed injection amount of the fuel instead of the reference amount of the fuel when the operation abnormality is detected at the start of the internal combustion engine ;
Ignition means for igniting the fuel ,
The control means increases the frequency of controlling the injection means so as to inject the reference amount of the fuel when the fuel is not ignited by the ignition means, and instead of the reference amount of the fuel, A start control device for an internal combustion engine, characterized in that the frequency of controlling the injection means is decreased so as to inject the fuel with the changed injection amount . A first temperature detecting means for detecting the engine temperature of the internal combustion engine;
The changing means changes the fuel injection amount to an increase side or a decrease side with respect to the reference amount in accordance with the detected engine temperature in addition to the specified phase amount. The start control device for an internal combustion engine according to claim 1. A second temperature detecting means for detecting an intake air temperature of the intake air sucked into the internal combustion engine;
The changing means changes the fuel injection amount to an increase side or a decrease side with respect to the reference amount in accordance with the detected intake air temperature in addition to the specified phase change amount. The start control device for an internal combustion engine according to claim 1 or 2. Determining means for determining an allowable range of an air-fuel ratio at which the internal combustion engine can be started according to the detected intake air temperature in addition to or instead of the detected engine temperature;
Determination means for determining whether or not to change the injection amount based on the determined allowable range of the air-fuel ratio in addition to or instead of the specified phase change amount;
When the determination means determines that the injection amount is to be changed, the control means controls the injection means to inject the changed injection amount of the fuel instead of the reference amount of the fuel. 4. The internal combustion engine start-up according to claim 3, wherein when the determination unit determines that the injection amount is not changed, the injection unit is controlled to inject the reference amount of the fuel. Control device.   The control means controls the injection means to inject the fuel with the changed injection amount instead of the fuel with the reference amount when the phase amount is specified by the specifying means, 5. The internal combustion engine according to claim 1, wherein when the phase amount is not specified by the specifying unit, the injection unit is controlled to inject the reference amount of the fuel. 6. Start control device.

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