JP2001214769A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device capable of taking proper measures in the occurrence of an abnormality in a valve timing variable mechanism in an internal combustion engine provided with valve timing variable mechanism and minimizing the deterioration of the engine operability. SOLUTION: According to the judgment of the abnormality of a valve operating characteristic variable device 40, more specifically, the operating phase slippage of an intake valve and the alignment slippage of a cam shaft by a first valve operating characteristic variable mechanism 42, the disconnection of a solenoid valve 44 for controlling the oil pressure supplied to the first valve operating characteristic variable mechanism 42 is judged. When the abnormality is detected, the stop of purge or the reduction in purge quantity is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for a valve timing variable mechanism for changing a valve timing of an intake valve and / or an exhaust valve, and for detecting an abnormality of the variable valve timing mechanism. And a control device having the same.

[0002]

2. Description of the Related Art A variable valve timing mechanism for changing the timing of opening and closing an intake valve and an exhaust valve of an internal combustion engine during engine operation has been known (for example, Japanese Patent Publication No. 5-43947). The variable timing mechanism has both a cam switching mechanism that changes the lift amount and the opening angle of the valve stepwise by switching cams, and a variable cam phase mechanism that changes the opening and closing timing of the valve steplessly.

Further, a canister for temporarily storing evaporative fuel generated in a fuel tank for supplying fuel to the internal combustion engine is provided, and an evaporative fuel emission prevention device for purging the evaporative fuel stored in the canister into an intake system of the internal combustion engine in a timely manner. Are also widely known (for example, Japanese Patent No. 2592432).

[0004]

In an engine equipped with the above-described cam phase variable mechanism and the evaporative fuel release prevention device, when the cam phase variable mechanism fails, the following problems occur, for example. That is, if the cam phase becomes uncontrollable during the idle operation of the engine with the valve timing being shifted to the advanced side from the valve timing suitable for the idle operation, the combustion of the gas to be exhausted is performed without being exhausted. The amount remaining in the chamber increases, and the amount of fuel to be supplied to the combustion chamber is smaller than normal. However, when purging the fuel vapor from the canister is performed on the premise that the intake valve and the exhaust valve are operated at the correct valve timing, the air-fuel ratio becomes over-rich, and the fuel supplied from the fuel injection valve is controlled by the air-fuel ratio feedback control. There is a problem that the fuel supply amount becomes extremely small and the fuel supply amount control becomes practically impossible. Therefore, there is a possibility that the operability of the engine may be significantly deteriorated.

The present invention has been made in view of this point. In an internal combustion engine having a variable valve timing mechanism, an appropriate action is taken when an abnormality occurs in the variable valve timing mechanism, and the engine operability is improved. It is an object to provide a control device capable of minimizing deterioration.

[0006]

According to a first aspect of the present invention, there is provided a valve timing changing means for changing at least one of an intake valve and an exhaust valve in accordance with an operation state of an internal combustion engine. Abnormality detection means for detecting an abnormality related to the valve timing changing means, a canister for adsorbing evaporated fuel generated in a fuel tank, a purge passage connecting the canister and an intake system of the engine, In a control device for an internal combustion engine, which is provided in the middle of a purge passage and includes a control valve that opens and closes the purge passage, and a control unit that controls the control valve, the control unit includes: an abnormality detection result of the abnormality detection unit. The opening degree of the control valve is changed according to Here, the “change of the valve timing” includes at least a change of the valve opening / closing valve timing (operation phase), and may further include a change of the valve lift and / or the opening angle (valve opening period). Good.

According to this configuration, the opening degree of the purge control valve that opens and closes the purge passage is changed in accordance with the detection result of the abnormality related to the valve timing changing means, so that the amount of fuel vapor to be purged when the abnormality is detected is reduced. By stopping the purge or stopping the purge, when an abnormality occurs in the valve timing changing means, it is possible to minimize the deterioration of the engine operability. Preferably, the purge control means reduces the opening of the purge control valve from a normal state when an abnormality of the valve timing changing means is detected.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an internal combustion engine and a control device thereof according to an embodiment of the present invention.
FIG. 4 is a diagram showing a configuration of a valve operating characteristic variable mechanism. In FIG. 1, reference numeral 1 denotes an internal combustion engine having, for example, four cylinders (hereinafter, simply referred to as "engine"). The engine 1 has a first valve operating characteristic for switching a valve lift amount and an opening angle of an intake valve and an exhaust valve in two stages. A variable valve operating characteristic device 40 having a variable mechanism 41 and a second variable valve operating characteristic mechanism 42 as a variable cam phase mechanism for continuously changing the opening / closing timing of the intake valve is provided.

A throttle valve 3 is disposed in the intake pipe 2 of the engine 1. A throttle valve opening (θTH) sensor 4 is connected to the throttle valve 3, and outputs an electric signal according to the opening of the throttle valve 3 to an electronic control unit (hereinafter referred to as (ECU)) 5. Supply.

A fuel injection valve 6 is provided for each cylinder in the middle of the intake pipe 2 and slightly upstream of an intake valve (not shown) between the engine 1 and the throttle valve 3. Each fuel injection valve 6 is connected via a fuel supply pipe 7 to a fuel pump unit 8 provided in a sealed fuel tank 9. The fuel pump unit 8 includes a fuel pump, a fuel strainer, The pressure regulator is configured integrally with a pressure regulator that sets the reference pressure to the atmospheric pressure or the tank internal pressure. The fuel tank 9 is provided with a tank internal pressure sensor 15 for detecting the pressure in the fuel tank 9, that is, the tank internal pressure PTANK, and a detection signal is supplied to the ECU 5.

The fuel injection valve 6 is electrically connected to the ECU 5, and the valve opening time is controlled by a signal from the ECU 5. Downstream of the throttle valve 3 of the intake pipe 2, an intake pipe absolute pressure (PBA) sensor 13 for detecting the intake pipe absolute pressure PBA and an intake temperature (TA) sensor 14 for detecting an intake air temperature TA as an outside air temperature are mounted. Have been.

Connected to the ECU 5 are a crank angle position sensor 16 for detecting a rotation angle of a crank shaft (not shown) of the engine 1 and a cam angle position sensor 17 for detecting a rotation angle of a cam shaft (not shown). The signal corresponding to the rotation angle of the crankshaft and the rotation angle of the camshaft is EC
It is supplied to U5. The crank angle position sensor 16 generates one signal pulse (hereinafter referred to as a “CRK signal pulse”) every fixed crank angle cycle (for example, a 30-degree cycle) and a signal pulse for specifying a predetermined angular position of the crankshaft. Further, the cam angle position sensor 17 detects a signal pulse (hereinafter, “CYL”) at a predetermined crank angle position of a specific cylinder of the engine 1.
Signal pulse) and a signal pulse (hereinafter referred to as a "TDC signal pulse") at the top dead center (TDC) at the start of the intake stroke of each cylinder. These signal pulses are used for various timing controls such as fuel injection timing, ignition timing, etc., and detection of an engine speed (engine speed) NE. The TD output from the cam angle position sensor 17
From the relative relationship between the C signal pulse and the CRK signal pulse output from the crank angle position sensor 16, the actual operation phase of the camshaft that drives the intake valve can be detected.

The engine 1 is provided with an engine water temperature sensor 18 for detecting the cooling water temperature TW, and a detection signal is supplied to the ECU 5. A three-way catalyst 20 is provided in the exhaust pipe 19, and O2 sensors 21 and 22 are mounted at upstream and downstream positions of the three-way catalyst 20, respectively. These O2 sensors 21 and 22 output electric signals corresponding to the oxygen concentration (air-fuel ratio) in the exhaust gas and supply them to the ECU 5.

Next, the structure of an evaporative emission control device for preventing the evaporative fuel generated in the fuel tank 9 from being released to the atmosphere will be described. A canister 33 is connected to the fuel tank 9 via a charge passage 31, and the canister 33 is connected to a downstream side of the throttle valve 3 of the intake pipe 2 via a purge passage 32. A charge control valve 36 is provided in the middle of the charge passage 31.

The operation of the charge control valve 36 is controlled by the ECU 5. The charge control valve 36 is opened when the tank internal pressure is high, and guides the fuel vapor in the fuel tank 9 to the canister 33. The charge control valve 36 is also opened when the abnormality detection of the evaporative emission control device is executed. The canister 33 has a built-in activated carbon for adsorbing the evaporated fuel in the fuel tank 9 and can communicate with the atmosphere via an atmosphere passage 37. A vent shut valve (open / close valve) 38 is provided in the middle of the atmosphere passage 37. The vent shut valve 38 is a so-called normally-closed valve whose operation is controlled by the ECU 5 and is opened at the time of refueling or during execution of a purge, and closed at other times. However, the vent shut valve 38 is opened and closed when the abnormality detection of the evaporative fuel emission prevention device is performed.

A purge control valve 34 is provided in the purge passage 32 between the canister 33 and the intake pipe 2. The purge control valve 34 is an electromagnetic valve configured so that the flow rate can be continuously controlled by changing the on-off duty ratio of the control signal (the opening degree of the control valve). It is controlled by the ECU 5.

According to this evaporative fuel release prevention device, the evaporative fuel generated in the fuel tank 9 at the time of refueling flows into the canister 33 via the charge passage 31 and is supplied to the canister 3.
It is adsorbed by the adsorbent in 3 and stored. When the purge control valve 34 is opened, the evaporative fuel temporarily stored in the canister 33 is purged together with the outside air sucked through the atmosphere passage 37 by the negative pressure in the intake pipe 2.
Is sucked into the intake pipe 2 and sent to each cylinder. In this way, the fuel vapor generated in the fuel tank 9 is prevented from being released to the atmosphere.

As shown in FIG. 2, the valve operating characteristic variable device 40 is a first valve for switching the valve lift and opening angle (hereinafter referred to as "first valve operating characteristic") of the intake valve and the exhaust valve in two stages. An operation characteristic variable mechanism 41, a second valve operation characteristic variable mechanism 42 as a cam phase variable mechanism for continuously changing the opening / closing valve timing of an intake valve, and a first valve operation characteristic adapted to high-speed operation suitable for high-speed operation of an engine. The first solenoid valve 43 that switches between the operation characteristic and the low-speed operation characteristic suitable for low-speed operation, and the opening degree of the opening and closing valve of the intake valve (hereinafter referred to as “operation phase”) are continuously changed in order to continuously change the valve timing. Second solenoid valve 4 that can be continuously changed
4 is provided. The lubricating oil of an oil pan 46 is supplied to the solenoid valves 43 and 44 under pressure by an oil pump 45. The specific configuration of the variable valve operation characteristic device 40 is disclosed in, for example, Japanese Patent Application No. 11-28618 filed by the present applicant.

According to the valve operating characteristic varying device 40, the exhaust valve is driven by one of a high-speed operation characteristic indicated by a solid line L1 and a low-speed operation characteristic indicated by a solid line L2 in FIG.
In the same figure, the range from the most advanced phase indicated by broken lines L3 and L4 to the most retarded phase indicated by chain lines L7 and L8 is centered on the high-speed operation characteristic indicated by solid line L5 and the low-speed operation characteristic indicated by solid line L6. Are driven in the phase of

The ECU 5 has functions such as shaping input signal waveforms from various sensors, correcting voltage levels to predetermined levels, and converting analog signal values to digital signal values, and a central processing circuit (hereinafter referred to as a central processing circuit). An output circuit that supplies drive signals to the fuel injection valve 6, the purge control valve 34, and the valve operating characteristic variable device 40, in addition to a storage unit that stores a calculation program executed by the CPU, a calculation result, and the like. And so on.

The CPU of the ECU 5 controls the amount of fuel supplied to the engine 1 in response to output signals from various sensors such as a crank angle position sensor 16, an intake pipe absolute pressure sensor 13, an engine water temperature sensor 18, and O2 sensors 21 and 22, In addition to executing the purge fuel amount control by the purge control valve 34 and the valve operation characteristic control according to the engine operating state, the abnormality detection process related to the valve operation characteristic variable device 40 described below is executed.

FIG. 4 shows that the operating phase CAIN of the intake valve is set to the target phase CAINCM by the second valve operating characteristic variable mechanism 42.
9 is a flowchart of a process for detecting a control deviation when performing control to match D, that is, an abnormality in which an actual operation phase does not match a target phase. This process is executed by the CPU of the ECU 5 every predetermined time.

In step S11, it is determined whether or not a phase variable control flag FVTC indicating "1" indicating that variable phase control for changing the operation phase of the intake valve is being executed is "1". When the target phase CAINCMD is 0 and the phase variable control is not being executed, the target phase change flag FC indicating that the target phase CAINCMD has changed by a predetermined value or more by "1".
MDCHANG is set to "0" (step S14).
At the same time, a down count timer tmFSB used to determine that there is a control deviation (abnormality determination) and a down count timer tmOKB used to determine that there is no control deviation (normality determination) are each a predetermined abnormality. A determination time TMFSB (for example, 10 seconds) and a predetermined normality determination time TMOKB (for example, 10 seconds) are set and started (step S15).

If FVTC = 1 and the phase variable control is being executed in step S11, the target phase change flag F
It is determined whether or not CMDCHANG is “1” (step S12). If FCMDCHANG = 1, the process immediately proceeds to step S17. Also, FCMDCHANG =
When it is 0, the current value CAINCMD of the target phase
It is determined whether the absolute value of the difference between (n) and the previous value CAINCMD (n-1) is equal to or greater than a predetermined value CMDVTCFS (for example, 5 degrees) (step S13), and | CAINCMD (n)
When −CAINCMD (n−1) | <CMDVTCFS and the change amount of the target phase CAINCMD is small,
While proceeding to step S14, | CAINCMD
(N) −CAINCMD (n−1) | ≧ CMDVTCF
If it is S, the target phase change flag FCMDCHAN
G is set to "1" (step S16), and step S16 is performed.
Proceed to 17.

In step S17, the actual operating phase CA
Whether or not IN is within a predetermined range substantially centered on the target phase CAINCMD, that is, a lower limit (CAINCMD-CAINCFS) obtained by subtracting a predetermined subtraction value CAINCFSL (for example, 2 degrees) from the target phase CAINCMD.
L) and a predetermined added value CAIN to the target phase CAINCMD.
The upper limit (C) obtained by adding CFSH (for example, twice)
AINCMD + CAINCFSH). Here, the actual operation phase CAIN is detected based on the relative phase relationship between the CRK signal pulse and the TDC signal pulse as described above. That is, as shown in FIG. 8, T when the cam operation phase is at the most retarded position.
A phase difference CAINZP between the DC signal pulse ZP and a predetermined CRK signal pulse YP is set as a reference phase, and an actual operation phase CAIN is detected as an advance amount from the reference phase. Specifically, when the generation time interval TCAIN between the predetermined CRK signal pulse YP and the TDC signal pulse XP and the generation time interval CRME between the CRK signal pulses are measured, and the CRK signal pulse is generated every crank angle of 30 °, CAIN =
Calculated as CAINZP-30 × TCAIN / CRME.

If the answer to step S17 is affirmative (YES) and the actual operation phase CAIN is within the range of the predetermined upper and lower limits, the abnormality determination timer tmFSB is set to the predetermined time TM
Set to FSB and start (step S18),
It is determined whether the value of the normality determination timer tmOKB is “0” (step S19). While tmOKB> 0,
This processing is immediately terminated, and the state is maintained (step S1).
If the answer to 7 is affirmative (YES), if tmOKB = 0, it is determined to be normal, the normal flag FOKB indicating "1" indicating no control deviation is set to "1", and there is a control deviation. Is set to “0” and the target phase change flag FCM
DCHANG is returned to “0” (step S20), and the process ends.

On the other hand, if the answer to step S17 is negative (NO),
That is, when the actual operation phase CAIN is not within the range of the predetermined upper and lower limit values, the normality determination timer tmOKB is set to the predetermined time T.
MOKB and start (step S2
1), it is determined whether the value of the abnormality determination timer tmFSB is “0” (step S22). As long as tmFSB> 0, the present process is immediately terminated. In this state (the answer of step S17 is negative (NO)), if tmFSB = 0, it is determined that there is an abnormality and there is no control deviation. "1"
Is set to "0", the control deviation flag FFSDB indicated by "1" indicating that there is a control deviation is set to "1", and the target phase change flag FCM
DCHANG is returned to “0” (step S23), and the process ends.

FIG. 5 is a time chart for explaining the processing of FIG. 4. FIGS. 5A to 5C show a normal case, and FIGS. 5D to 5F show an abnormal case. Is shown. That is, when the actual operating phase CAIN follows with a slight delay in response to the change in the target phase CAINCMD as shown in FIG.
= 0, and a normality determination is made (FIG. 9B). On the other hand, when the actual operating phase CAIN does not quickly follow the change in the target phase CAINCMD as shown in FIG. 4D, the timer tmFSB = 0 at time t2.
Is determined, that is, a determination is made that there is a control deviation.

FIG. 6 is a flowchart of a process for detecting disconnection of the solenoid of the solenoid valve 44. This process is executed by the CPU of the ECU 5 at predetermined time intervals. Step S31
Then, the duty ratio DDOUT of the signal for driving the solenoid of the solenoid valve 44 is changed to the predetermined duty ratio DDVTFSLM.
(For example, 50%) and determine whether
If T> DDVTFSLM, it is determined whether the current value IACTVTC supplied to the solenoid of the solenoid valve 44 is smaller than a predetermined current value IACTFSLM (for example, 450 mA) (step S32). And DDOUT
≤ DDVTFSLM or IACTVTC
If ≧ IACTFSLM, the down-count timer tmFSA is set to a predetermined time TFSA (for example, 5 seconds) and started (step S33), and this processing ends.

On the other hand, the answers of steps S31 and S32 are both affirmative (YES), that is, DDOUT> DDVTFS
If LM and IACTVTC <IACTFSLM, the current value IACTTVC is small despite the large duty ratio DDOUT of the drive signal, so it is determined that the possibility of disconnection is high, and the value of the timer tmFSA is “0”. Is determined (step S34). t
This process is immediately terminated while mFSA> 0, and tmFSA
When SA = 0, the determination of disconnection is determined, and a disconnection flag FFSDA indicating this is set to "1" is set to "1" (step S35), and this processing ends.

FIG. 7 shows the case where there is a misalignment, that is, the mounting position of the cam shaft is deviated from the normal position.
FIG. 9 is a flowchart of a process for detecting a case where the phase of a TDC signal pulse is originally shifted. This process is performed, for example, immediately after the ignition switch is turned on.
Executed by PU.

In step S41, the actual operation phase CAIN
Is in the most retarded phase CAINZP (the valve operating characteristic is
3), ie, the actual operation phase CA when the cam phase variable control is not executed.
It is determined whether or not IN0 (center value is 0) is within a range between a predetermined upper limit value CAIN0H and a predetermined lower limit value CAIN0L. When the answer is negative (NO), that is, CAIN>
If CAIN0H or CAIN <CAIN0L, it is determined that there is an alignment shift, the alignment shift flag FFSDC indicating this is set to "1" is set to "1" (step S42), and the process ends.

FIG. 9 is a flowchart of a process for controlling the opening of the purge control valve 34. This process is executed by the CPU of the ECU 5 at predetermined time intervals. Steps S51 to S5
In 3, it is determined whether or not the disconnection flag FFSDA, the control deviation flag FFSDB, and the alignment deviation flag FFSDC set in the processes of FIGS. 4, 6 and 7 are set to “1”, and all the flags are set to “0”. , That is, when no abnormality is detected, the normal purge is performed in accordance with the engine operating state (for example, the purge control valve opening is calculated in accordance with the engine speed NE and the intake pipe absolute pressure PBA). Control is performed (step S54).

On the other hand, if FFSDA = 1 and the disconnection of the solenoid of the solenoid valve 44 is detected, the purge control valve 34 is decreased in opening degree from the time of the normal control to perform the purge (step S56), and the FFSDB is executed. = 1 or FFDC =
If it is 1, and control deviation or alignment deviation is detected, the purge control valve 34 is fully closed to stop purging (step S55). Note that FFSDC = 1
However, when the misalignment is detected, the purge amount may be reduced according to the misalignment amount instead of stopping the purge.

As described above, in this embodiment, when an abnormality of the second valve operating characteristic variable mechanism and the solenoid valve 44 for controlling the same is detected, the purge amount is reduced or the purge is stopped. Therefore, for example, in an idle state where the most retarded phase is desirable as the operation phase of the intake valve, it is possible to avoid a problem that the fuel amount cannot be controlled by performing a normal purge while the actual operation phase is shifted in the advance direction. can do. As a result, it is possible to minimize deterioration of drivability when an abnormality occurs in the variable valve operation characteristic mechanism.

In this embodiment, the following 1) to 1
0), the disconnection of the solenoid valve (FFSDA = 1) and the control deviation (F
FSDB = 1) or misalignment (FFSDC)
= 1) is detected, the following 2),
It is desirable not to execute the abnormality (deterioration) detection processing of 3), 5) and 7) to 10). This is because the abnormality detection may not be performed accurately. In other words, when any of the flags FFSDA, FFSDB or FFSDC is “1”, the following 1) O2 sensor 2
1) abnormality detection processing, 4) abnormality detection processing of the fuel injection valve 6,
And 6) Only the deterioration detection processing of the O2 sensor 22 is executed.

1) Abnormality detection processing of the O2 sensor 21 In this processing, when the sensor output is larger than a predetermined upper limit value, or when the sensor output while the fuel supply to the engine is shut off indicates a rich air-fuel ratio, it is determined that the disconnection has occurred. When the state in which the sensor output indicates the lean air-fuel ratio has continued for a predetermined time or more, it is determined that a short circuit or an output stagnation has occurred.

2) Abnormality detection processing of the intake pipe absolute pressure sensor 13 This processing is based on the throttle valve opening θTH detected by the throttle valve opening sensor 4 and the engine speed NE detected by the crank angle position sensor 16. Abnormality is detected by comparing the predicted intake pipe absolute pressure calculated as described above with the intake pipe absolute pressure PBA indicated by the sensor output.

3) Abnormality detection processing of the throttle valve opening sensor 4 In this processing, based on the intake pipe absolute pressure PBA detected by the intake pipe absolute pressure sensor 13 and the engine speed NE detected by the crank angle position sensor 16. The abnormality is detected by comparing the predicted throttle valve opening calculated by the above with the throttle valve opening θTH indicated by the sensor output.

4) Processing for Detecting Abnormality of Fuel Injection Valve 6 In this processing, the parameter value calculated based on the air-fuel ratio correction coefficient KO2 set in accordance with the outputs of the O2 sensors 21 and 22 is out of the predetermined range. When the fuel injection valve 6
Is determined to be leaking or clogged.

5) Deterioration detection processing of O2 sensor 21 In this processing, sensor deterioration is detected based on the inversion cycle of the sensor output when the fuel supply amount is feedback-controlled according to the output of the O2 sensor 21. In addition,
When a proportional oxygen concentration sensor whose output is substantially proportional to the air-fuel ratio is used instead of the O2 sensor 21, deterioration is detected based on a change in the sensor output when the control air-fuel ratio is changed.

6) Deterioration detection process of O2 sensor 22 In this process, if the sensor output is inverted, it is determined that the sensor output is normal, and if not, the change in the sensor output when the control air-fuel ratio is changed is determined. Deterioration is detected based on this.

7) Deterioration detection processing of the three-way catalyst 20 In this processing, deterioration is detected based on the inversion cycle of the output of the O2 sensor 22 when the control air-fuel ratio is vibrated at a predetermined cycle. 8) Abnormality Detection Process of Engine Water Temperature Sensor 18 In this process, an abnormality is detected based on a sensor output after a lapse of a predetermined time from the completion of starting.

9) Thermostat abnormality detection processing In this processing, the abnormality of the thermostat that opens and closes the cooling water passage is detected by comparing the degree of increase of the engine water temperature TW with the degree of increase of the engine water temperature estimated from the fuel supply amount. You. Thermostat is normal (not open) when actual rise is greater than estimated rise
Is determined. The thermostat automatically opens and closes a cooling water passage that circulates engine cooling water in accordance with the temperature of the engine cooling water.The thermostat is provided to close the cooling water passage at the time of cold start of the engine and promote the temperature rise of the engine. ing.

10) Abnormality detection processing of the evaporative emission control device In this processing, the purge control valve 34 and the charge control valve 36
And opening and closing the vent shut valve 38 while maintaining the tank internal pressure P
By monitoring TANK, the presence or absence of leakage of the fuel tank 9, the canister 33 and the like is detected.

In the above-described embodiment, the valve operating characteristic varying device 40 and the ECU 5 constitute valve timing changing means, and the ECU 5 constitutes abnormality detecting means and purge control means. More specifically, the processes in FIGS. 4, 6, and 7 correspond to the abnormality detection unit, and the processes in FIG. 9 correspond to the purge control unit.

The present invention is not limited to the embodiment described above, and various modifications are possible. For example, in the above-described embodiment, the second valve operation characteristic variable mechanism 42 is configured to be able to change only the operation phase of the intake valve, but only the operation phase of the exhaust valve or both the operation phases of the intake valve and the exhaust valve. It may be changeable.

In the above-described embodiment, an example in which the abnormality of the second valve operating characteristic variable mechanism 42 and the electromagnetic valve 44 is detected has been described, but the abnormality of the first valve operating characteristic variable mechanism 41 and the electromagnetic valve 43 is detected. A similar fail-safe process may be performed in the purge control according to the result. As the abnormality detection in this case, an abnormality in which the operating characteristics of the intake valve or the exhaust valve do not become the characteristics as instructed by the switching command, and a disconnection of the solenoid of the electromagnetic valve 43 are detected.

[0049]

As described above in detail, according to the present invention, the degree of opening of the purge control valve for opening and closing the purge passage is changed in accordance with the result of detection of the abnormality related to the valve timing changing means. By reducing the amount of evaporated fuel to be purged at some times or by stopping the purge, it is possible to minimize the deterioration of the engine operability when an abnormality occurs in the valve timing changing means.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an internal combustion engine and a control device thereof according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a variable valve operating characteristic device.

FIG. 3 is a diagram showing valve operating characteristics.

FIG. 4 is a flowchart of a process for detecting a control deviation of the valve operating characteristic variable device.

FIG. 5 is a time chart for explaining the processing of FIG. 4;

FIG. 6 is a flowchart of a process for detecting disconnection of a solenoid valve.

FIG. 7 is a flowchart of a process for detecting a misalignment of a cam shaft.

FIG. 8 is a diagram for explaining a definition of an actual operation phase (CAIN) of the camshaft.

FIG. 9 is a flowchart of a process for controlling the opening of the purge control valve.

[Description of Signs] 1 Internal combustion engine 2 Intake pipe 5 Electronic control unit (valve timing changing means, abnormality detecting means, purge control means) 9 Fuel tank 16 Crank angle position sensor 17 Cam angle position sensor 31 Charge passage 32 Purge passage 33 Canister 34 Purge control valve 40 Variable valve operating characteristic device (valve timing changing means) 41 First valve operating characteristic variable mechanism 42 Second valve operating characteristic variable mechanism 43, 44 Solenoid valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 25/08 301 F02M 25/08 301H F-term (Reference) 3G084 BA23 BA27 CA01 CA03 DA11 DA30 DA31 DA33 EB11 EB22 EC06 FA10 FA11 FA20 FA30 FA33 FA38 3G092 AA11 DA01 DA02 DA03 DC01 DE01Y DE19S DE19Y DG09 EA02 EA09 EA14 EA17 EC01 EC08 FA03 FB02 FB03 GA01 GA04 HA05Y HA05Z HA06Y HA06Z HA13Z HD06Y HD06Z HE01Z HE03Z HE08

Claims (1)

[Claims] A valve timing changing means for changing at least one of an intake valve and an exhaust valve in accordance with an operation state of the internal combustion engine; an abnormality detecting means for detecting an abnormality relating to the valve timing changing means; A canister for adsorbing fuel vapor generated in a fuel tank, a purge passage connecting the canister and an intake system of the engine, a purge control valve provided in the middle of the purge passage to open and close the purge passage, A control device for an internal combustion engine comprising: purge control means for controlling the purge control valve; wherein the purge control means changes an opening degree of the control valve in accordance with an abnormality detection result of the abnormality detection means. Control device for an internal combustion engine.