JP3311212B2 - Failure detection device for evaporative fuel control device of internal combustion engine and misfire detection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a failure of an evaporative fuel control device of an internal combustion engine, that is, a failure of a canister and various valve devices constituting the evaporative fuel control device, and a failure for detecting a failure of an evaporative fuel passage and the like. The present invention relates to a detection device and a misfire detection device that performs misfire detection.

[0002]

2. Description of the Related Art Generally, in an internal combustion engine for an automobile,
In order to prevent air pollution due to fuel evaporative gas (mainly harmful HC components), evaporated fuel generated from an evaporation source such as a fuel tank is introduced into a canister to be adsorbed and collected, and this is collected by the canister and an intake system of an internal combustion engine. Is supplied to the intake system via an evaporative fuel supply passage provided between the fuel cell and the intake passage. Also, if the supply of evaporative fuel is performed unconditionally, the air-fuel ratio of the air-fuel mixture will fluctuate greatly and the operating performance of the internal combustion engine will deteriorate, so a purge control valve is provided in the evaporative fuel supply passage, and An evaporative fuel control device that opens the purge control valve according to a control command and supplies evaporative fuel to the intake system only under operating conditions (when executing air-fuel ratio feedback control) where there is no problem even if evaporative fuel is supplied to the intake system. Used. In addition, from the viewpoint of enhancing air pollution prevention in recent years, this failure is detected at an early stage when a failure occurs in the evaporative fuel control device such as damage to the evaporative fuel supply passage, deterioration or breakage of the canister, or failure of the purge control valve. It is thought to warn and urge repairs. An apparatus for detecting such a failure is provided by the California Air Resources Board (hereinafter referred to as CARB).
"Abbreviated as" Technica "
l Support Document "on page 15. Hereinafter, the device proposed by CARB will be described with reference to FIG. 9, reference numeral 100 denotes an air cleaner, 10 denotes a fuel tank for storing fuel, 11 denotes a canister that adsorbs and collects evaporative gas generated from the fuel tank 10, and 19 denotes introduction of the fuel adsorbed by the canister 11 to the internal combustion engine. The purge control valve to be controlled, 20 is the canister 1
1 canister close valve for opening and closing the open-to-atmosphere end, 16
Is a pressure detection sensor for measuring the pressure in the system of the evaporative fuel control device, 3 is an intake pipe, and 51 is a throttle valve.

Next, a failure detection operation of the evaporative fuel control device disclosed in CARB will be described with reference to FIG.
First, in a predetermined operating state determined in advance, the canister close valve 20 is closed under the control of an ECU (engine control unit or electric control unit) as a failure detection device, and then the purge control valve 19 is operated. With this operation, the pressure in the system of the device decreases due to the manifold negative pressure of the internal combustion engine. This pressure fluctuation is detected by the ECU based on the output from the pressure detection sensor 16. Here, if there is a failure in the evaporative fuel control device (for example, if the piping between the fuel tank 10 and the canister 11 is disconnected, or if the evaporative fuel control device is leaking), the pressure in the system becomes lower. Since there is no negative pressure, the pressure in the system does not change or changes little. Further, if the evaporative fuel control device is normal, the pressure in the system becomes negative, so that the pressure in the system changes. As described above, it is known that the pressure operation in the system of the evaporative fuel control device differs depending on whether the evaporative fuel control device has failed or is normal.
The ARB detects the pressure change to detect a failure of the fuel vapor control device.

[0004]

However, the above C
In the ARB device, for example, under a predetermined condition such as a high outside air temperature, a condition for increasing the amount of evaporative fuel is satisfied. Under such conditions, when the above-described failure detection operation is performed, that is, when the failure detection device closes the canister close valve in a predetermined predetermined operation state and then operates the purge control valve, The pressure in the system of the evaporative fuel control device does not decrease because the amount of evaporative fuel generated is large. For this reason, the pressure change in the system does not show a normal change as shown by a solid line in FIG. 10, but shows a change as shown by a dotted line F1 in FIG. In this case, although the fuel vapor control device is normal, it is determined that the device is abnormal, and whether the abnormality is due to a large leak,
It is not clear whether the determination is abnormal regardless of the normal condition due to the large amount of fuel evaporation. There was a problem to say. Further, for example, under predetermined conditions such as when driving on a rough road, the fuel in the fuel tank fluctuates, so that the pressure in the system fluctuates due to the fuel fluctuation in the fuel tank, and a condition that becomes abnormal when a failure is detected is satisfied. I do. Under such conditions, when the failure detection operation is performed, that is, when the failure detection device closes the canister close valve and then operates the purge control valve in a predetermined operating state, the system detects a failure. The behavior of the pressure fluctuation is as shown by the dotted line F2 in FIG. 10, and therefore, it may be determined that the device is abnormal even though it is normal. There was a problem to say.
Further, in the conventional misfire detection, a cycle of a signal output from a rotation speed detection sensor for detecting a rotation speed of the internal combustion engine is calculated, a cycle of a signal output next time is predicted, and the predicted value is compared with the predicted value. Misfire is detected from the deviation amount of the cycle of, for example, when traveling on a rough road (rocky road), when there is a large stone and the stone hits the tire, the vehicle speed suddenly decreases, When the internal combustion engine and the transmission are directly connected, the rotational speed of the internal combustion engine also drops rapidly. Then, the cycle of the output of the rotational speed detection sensor also changes suddenly, and the predicted cycle and the actual cycle greatly deviate from each other. There was a problem to say.

[0005]

According to a first aspect of the present invention, there is provided a failure detecting device for an evaporative fuel control device, comprising: a pressure detection sensor for detecting an internal pressure in a system of the evaporative fuel control device; The operation of the purge control valve 19 is controlled, and after a lapse of a predetermined time (TRX),
When the purge control valve 19 is stopped,
Open the rose valve 20 and output the pressure detection sensor 16
To near atmospheric pressure (PINT) and then
A predetermined time (TR2) has passed since the closed valve 20 was closed.
When it is determined that the output value of the pressure detection sensor 16 after the passing is greater than a predetermined value, the control means (control unit 2) for stopping the failure detection of the evaporative fuel control device is provided. According to a second aspect of the present invention, there is provided a failure detection device for an evaporative fuel control device, wherein a fuel amount detection sensor for detecting a fuel amount of a fuel evaporation source and a variation in an output value from the fuel amount detection sensor are larger than a predetermined value. And control means (control unit 2A) for stopping the failure detection of the evaporative fuel control device when the determination is made. The misfire detection device for an internal combustion engine according to claim 3 is configured such that a fuel amount detection sensor 21 that detects a fuel amount of an evaporation source of the fuel of the internal combustion engine, and that a fluctuation amount of an output value of the fuel amount detection sensor is larger than a predetermined value. And control means (control unit 2A) for stopping the misfire detection when the determination is made.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, a first embodiment of a failure detection device according to the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram showing a first embodiment of a failure detection device for an evaporative fuel control device according to the present invention. In FIG. 1, reference numeral 1 denotes an engine, and 2 denotes an analog input signal and a digital input signal. The engine 1 includes an input interface unit, an arithmetic processing unit, and a driver unit for driving various loads.
This is a control unit as control means of the present invention for controlling a fuel gauge and an ignition system (not shown). 3 is an intake pipe of the engine. Reference numeral 4 denotes an air flow meter for measuring the amount of intake air of the engine 1, for example, a heat-sensitive flow meter. 5 is a throttle opening sensor for detecting the opening of the throttle valve 51; 6 is an intake pipe pressure sensor for detecting the pressure of the intake pipe 3; 7 is an exhaust sensor for detecting oxygen concentration in the exhaust; A rotation speed detection sensor 9 for detecting the number is a fuel injection valve for injecting fuel into the intake pipe 3. The control unit 2 calculates a basic fuel amount necessary for the engine 1 based on signals from an air flow meter 4, a throttle opening sensor 5, an intake pipe pressure sensor 6, a rotation speed detection sensor 8, and the like, and detects an operation state. A feedback correction value is calculated for the fuel injection amount by the fuel injection valve 9 in accordance with a signal from the exhaust sensor 7 so that a predetermined air-fuel ratio is obtained according to the operating state, and the air-fuel ratio is feedback-controlled based on the correction value. The control unit 2 also performs optimal control on an ignition system (not shown) according to the operating state based on the signals of the above-described sensors and the like. Reference numeral 10 denotes a fuel tank as an evaporation source, 11 denotes a canister filled with an adsorbent 12 such as activated carbon, and 13 communicates between the fuel tank 10 and the canister 11 so that evaporative fuel generated inside the fuel tank 10 is removed. An evaporative fuel introduction passage, which is introduced into the canister 11, is a pressure detection sensor that detects an internal pressure in the system of the evaporative fuel control device.
For example, a pressure sensor that generates an output signal proportional to pressure is used. Also, the canister close valve 20
Is a valve that closes the canister open-to-atmosphere end for failure detection in response to a command from the control unit 2. Further, the intake pipe 3 downstream of the throttle valve 51 and the canister 11 are communicated with each other through the evaporated fuel supply passages 17 and 18, and a purge control valve 19 is provided in the middle thereof.
Opens and closes the evaporative fuel supply passages 17 and 18 in response to an open / close command from the control unit 2 and opens the purge control valve 19 under conditions that allow the supply of evaporative fuel to the intake pipe 3 (at the time of executing the air-fuel ratio feedback control). The fuel vapor adsorbed and collected in the canister 11 is supplied by the negative pressure of the intake pipe 3. The control unit 2 performs the operation of evaporative fuel control and the failure detection of the evaporative fuel control device based on the flow shown in FIGS. Therefore, the fuel vapor control device is constituted by the fuel tank 10, the canister 11, the purge control valve 19, the canister close valve 20, the passages 13, 17, and 18, and the control unit 2 which executes the flow of FIGS. , And the pressure detection sensor 16 and FIG.
The failure detection device is constituted by the control unit 2 executing the flow of No. 3.

Next, the failure detection operation of the evaporative fuel control device configured as described above will be described with reference to the flowcharts of FIGS. 2 and 3 and the operation diagrams of FIGS. 2 and 3 is performed for each main routine process of the control unit 2 (that is, for each evaporated fuel control process).
The calculation is repeatedly performed by the control unit 2 every 0 mSEC. First, in S (step) 101, a condition flag indicating the progress of the failure detection of the evaporative fuel control device is read, and in S102 to S104, the process jumps to each step along each condition. S1
If the condition does not correspond to any of the conditions from 02 to S104, it is determined in S105 whether or not the canister close valve 20 is closed. If "NO", the pressure detection for detecting the internal pressure of the evaporative fuel control device is performed in S106. A sensor value (hereinafter abbreviated as P) is read, and P is set to P1 in S107.
Save as Thereafter, in S108, the purge control valve 19
Is stopped, and the canister close valve 20 is closed in S109. By the operations of S108 and S109, the inside of the evaporative fuel control device is sealed. On the other hand, if "Yes" in the determination of whether or not the canister close valve 20 is closed in S105, P1 is detected, meaning that the canister close valve 20 is already closed, and in this case, the process jumps to S110. Next, in step S110, after the purge control valve 19 is stopped and the canister close valve 20 is closed, it is determined whether or not a TR1 time (for example, 15 sec) has elapsed. However, in the determination of S110, “Ye
s "means that the TR1 time has elapsed after the purge control valve 19 was stopped and the canister close valve 20 was closed. In this case, it is determined in S111 whether the purge control valve 19 was stopped. "Ye" is determined in S111.
In the case of "s" , it means that the vehicle passes for the first time after the elapse of TR1 time. Therefore, P is read in S112 and S113
Is stored as P2 in step S114, and the purge control valve 19 is stored in step S114.
Works. Operating the purge control valve 19 in S114 means that the pressure in the system of the evaporative fuel control device is reduced by the pressure (negative pressure) drawn by the engine 1. On the other hand, if “NO” in the determination as to whether or not the purge control valve 19 has been stopped in S111, it means that P2 has been detected and the purge control valve has already been operated, so that the flow jumps to S115. Next, in S115, the purge control valve 19 is operated, and after closing the canister close valve 20, it is determined whether or not the TRX time (for example, 30 sec) has elapsed. If "NO", P is read in S116. In step S117, a determination is made that P ≦ PP1 (predetermined pressure, that is, a determination value). In the determination of P ≦ PP1 in S117, “N”
In the case of "O", the purge control valve 19 is operated to close the canister close valve 20, but the state is that P has not yet reached PP1, so the routine returns. On the other hand, the determination in S117 is "Yes". In the case of "", after the purge control valve 19 is operated and the canister close valve 20 is closed, P reaches PP1 (predetermined pressure) or PP
It means that the value has become 1 or less (a large leak state, not a large amount of evaporative gas), the P read in S116 in S118 is stored as P3, and the purge control valve 19 is stopped in S119. Stopping the purge control valve 19 in S119 means maintaining the pressure in the evaporative fuel control device reduced to PP1. And then S120
To stop the purge control valve 19, and close the canister close valve 2.
After closing 0, it is determined whether or not the TR2 time (for example, 15 sec) has elapsed. If “NO”, the flag 1 is set in S121 and the process returns. However, if the determination in S120 is "Yes", it means that the TR2 time has elapsed after the purge control valve 19 is stopped and the canister close valve 20 is closed, so that P is read in S122, and P is read in S123. P is stored as P4, and the canister close valve 20 is opened in S124. In S125, using P1 to P4 at each point detected so far, (P4
-P3)-(P2-P1) <PP2 is determined. still,
(P4-P3) indicates the degree of pressure change (sealability) and the degree of generation of vaporized gas after TR2 (for example, 15 sec) from P3 reduced by the engine intake pressure (negative pressure), and (P2-P1) indicates , TR1 from almost atmospheric pressure
(E.g., 15 sec) indicates the degree of generation of vaporized gas after a time, and the predetermined pressure of PP2 indicates a pressure of an error level due to a difference in state. If “Yes” in the determination of S125,
Evaporated fuel control device (evaporation system) is determined in S126 because vaporized gas is little generated or no vaporized gas is generated and the sealing performance in the negative pressure state in the evaporated fuel control device is good. It is determined that the operation is normal, and in S127, the failure detection operation of the evaporative fuel control device ends, and the process returns. On the other hand, (P4-P3)-(P2-P1) of S125
If “NO” in the determination of PP2, it means that (P4−P3) is extremely larger than (P2−P1), that is, the sealing performance in the negative pressure state is poor (leakage is present), and S128
Fuel pressure control device (evaporation system) due to the fact that P dropped to PP1 or less while sealing performance was poor at negative pressure
Is abnormal and there is a small leak, and the failure detection operation of the evaporative fuel control device is terminated in S127 and the process returns. Also S11
5, the purge control valve 19 is operated and the canister close valve 2 is operated.
When the TRX time (for example, 30 sec) has elapsed after closing 0, if “Yes” in the determination of whether P has not reached PP1 during the TRX time (due to a large leak and a large amount of vaporized gas), the time is over. S129
To stop the purge control valve 19, and open the canister close valve 20 in S130. Then, P is read in S131, and determination of P ≧ PINT (pressure near the atmospheric pressure) is performed in S132. That is, P in the operations of S129 to S132
The P which has been in a negative pressure without reaching P1 is raised to almost the atmospheric pressure. P ≧ PIN in S132
In the case of “NO” in the determination of T, the purge control valve 19 is stopped and the canister close valve 20 is opened, but P
Does not rise to the vicinity of PINT, the flag 2 is set in S133, and the routine returns. On the other hand, if “Yes” in the determination of P ≧ PINT in S132, it means that P has risen to PINT for the first time after the purge control valve is stopped and the canister close valve is opened. To close the inside of the evaporative fuel control device from almost atmospheric pressure.
Next, after sealing the inside of the evaporative fuel control device from the substantially atmospheric pressure state in S135, it is determined whether or not the TR2 time (for example, 15 sec) has elapsed. If “NO”, the flag 3 is set in S136. To return. On the other hand, S135
After sealing the inside of the evaporative fuel control device from the substantially atmospheric pressure state, it is determined whether or not TR2 time (for example, 15 sec) has elapsed. If “Yes”, P is read in S137, and the canister is closed in S138. Open the valve and S139
To determine P ≧ PP3 (PP3 is PINT + α). S
In the case of “NO” in the determination of P ≧ PP3 (PP3 is PINT + α) at 139, the inside of the evaporative fuel control device is sealed and TR
This means that the pressure in the evaporative fuel control device has not risen even after two hours have passed. In this case, the evaporative fuel control device (evaporation system) is abnormal at S140 and has a large leak. The detection of the failure of the control device is terminated and the routine returns. On the other hand, P ≧ PP3 (P
(P3 is PINT + α) If “Yes” in the determination, the inside of the evaporative fuel control device is sealed and P
Since it means that it has increased to 3 or more, it is determined that the vaporized gas amount is large in S141, the failure detection of the evaporative fuel control device is stopped in S142, and the routine returns. The time until the failure is detected again when the failure detection operation is completed or when the failure detection operation is stopped is not flowed.
It is better to detect the failure again at the in interval. Further, in the above description, the failure was detected based on the pressure change in the system of the evaporative fuel control device. However, it goes without saying that the failure can also be detected by the absolute value of the pressure change.

Next, a description will be given based on the operation diagrams of FIGS. 4 and 5. FIG. 4 is an operation diagram when the evaporative fuel control device is normal (no evaporated gas) and abnormal (small leak). First, the purge control valve 19 is stopped, the internal pressure in the evaporative fuel control device immediately before the canister close valve is closed from the open state of the canister close valve is stored as P1, and the canister close valve 20 is closed. By closing the canister close valve 20, the inside of the fuel vapor control device is sealed. After closing the canister close valve 20, TR
After 1 sec, the internal pressure in the evaporated fuel control device immediately before the purge control valve is opened is stored as P2, and the purge control valve 19 is opened. By opening the purge control valve 19, the pressure in the fuel vapor control device is reduced by the pressure (negative pressure) sucked by the engine 1, and when the pressure drops to a predetermined pressure PP1, the pressure in the fuel vapor control device at that time is set to P3. Remember. Then, the purge control valve 19 is stopped again and maintained for TR2 time. The pressure in the evaporative fuel control device after TR2 hours is stored as P4. As described above, P1 to P4 are detected.
Can be determined to be not a large leak or a vaporized gas large state because P3 can be lowered to PP1 or less. Since P3 is a negative pressure state, the behavior of P3P4 indicates that the evaporative fuel control device is normal (no vaporized gas) and abnormal (a small leak exists). Can be determined. FIG. 5 is an operation diagram when the fuel vapor control device is abnormal (there is a large leak) and when the vaporized gas is large. First, the purge control valve 19 is stopped, the internal pressure in the evaporative fuel control device immediately before the canister close valve is closed from the open state of the canister close valve is stored as P1, and the canister close valve 20 is closed. By closing the canister close valve 20, the inside of the fuel vapor control device is sealed. After the canister close valve 20 is closed, the internal pressure in the evaporative fuel control device immediately before the purge control valve is opened after TR1Sec is set to P
2 and the purge control valve 19 is opened. When the purge control valve 19 is opened, the pressure drops to PP1 or less in a normal state (with no evaporative gas) and in an abnormal state (with a small leak). When it is determined that there is a large leak and the vaporized gas is in a large state, the purge control valve 19 is stopped, the canister close valve 20 is opened, and the pressure in the fuel vapor control device is increased to PINT (almost atmospheric pressure) (pressure). The canister close valve 20 is closed again, and if the pressure increases by a predetermined pressure PP3 (PINT + α) or more within TR2Sec, it is determined that the vaporized gas is large, and the failure detection is stopped. In other cases, it can be determined that the evaporative fuel control device is abnormal (there is a large leak). If the pressure does not drop below PP1, the pressure is raised to the atmospheric pressure by opening and closing the canister close valve 20. However, the canister close valve 20 does not need to be operated in this way. In this case, the point in time at which the pressure change is to be observed may be determined in advance. According to the first embodiment described above, it is possible to more reliably detect a failure of the evaporative fuel control device without erroneously detecting a failure as in the related art.

Embodiment 2 Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a configuration diagram showing Embodiment 2 of the failure detection device for the evaporative fuel control device according to the present invention. In the second embodiment, in addition to the configuration of the first embodiment shown in FIG. 1, a fuel amount detection sensor 21 for detecting the amount of fuel in the fuel tank 10 is provided. In addition to the functions of the unit 2, a control unit 2A is provided for detecting when the vehicle is running on a rough road and stopping the failure detection.

Next, a failure detection operation of the evaporative fuel control device performed by the failure detection device according to the second embodiment configured as described above will be described with reference to a flowchart of FIG. Note that FIG. 7 illustrates steps of a portion different from FIG. That is, the control unit 2A
In steps S125 to S128, a process for determining whether or not the vehicle is traveling on a rough road is performed, and if it is determined that the vehicle is traveling on a rough road, a process of stopping failure detection is performed. 2, 3 and 7 performed by the control unit 2A is similar to the control unit 2 for each main routine process, for example, 20 units.
The calculation is repeatedly performed for each mSEC. S125
If the determination of (P4−P3) − (P2−P1) <PP2 (predetermined pressure) is “NO”, the fuel level after filter processing (hereinafter abbreviated as LT) in S201, for example, the filter processing of the primary filter After that, the fuel level = the fuel level after the previous filtering process × the filter coefficient + the current instantaneous fuel level (1−filter coefficient) is read.
In S202, an instantaneous fuel level (hereinafter abbreviated as LTi) that has not been filtered is read. In S203,
LT-LTi |> LL1 (predetermined amount, for example, 20% of fuel half), and if "NO", the fuel fluctuation in the fuel tank is small, that is, the pressure fluctuation in the evaporative fuel control device (evaporation system) is It means that it is not the effect of the bad road, and in S128, the evaporative fuel control device (evaporation system)
It is determined that there is a small leak due to an abnormality, and in S127, the failure detection of the evaporative fuel control device ends and the process returns. On the other hand, S203
To determine | LT−LTi |> LL1, and “Yes”
In the case of, it means that the fuel fluctuation in the fuel tank is large, that is, the pressure fluctuation in the evaporative fuel control device (evaporation system) is caused by the bad road, and it is determined in S204 that the vehicle is now running on a bad road. Then, in S142, the failure detection of the evaporated fuel control device is stopped, and the process returns. As in the first embodiment, when the failure detection is completed or when the failure detection is stopped, the time until the failure is detected again is, for example, at a 10-Min interval when the failure detection is completed, and at a 5-Min interval, for example, when the failure detection is stopped. It should be detected. Thus, it can be determined that the vehicle is traveling on a rough road and the fuel vapor control device is abnormal (there is a small leak). In the case where the sensor 21 is a fuel level gauge, for example, when the fuel in the fuel tank fluctuates greatly depending on the operating state (acceleration / deceleration, etc.), the filter processing detects the instantaneous value at that time and outputs it as it is. Means that the fuel level is output and the filter level is multiplied by a filter coefficient (average coefficient) or the like to perform averaging. The above-described calculation method is called a first-order filter. According to the second embodiment, a failure is not erroneously detected.

Next, an embodiment of the misfire detection device according to the present invention will be described. The misfire detection device shown in FIG. 6 includes a rotation speed detection sensor 8, a fuel amount detection sensor, and a control unit 2A that detects misfire or inhibits misfire detection based on the output of these sensors. Control unit 2A
Performs optimal control on the ignition system as well as the control unit 2. The operation of the misfire detection device will be described with reference to the flowchart of FIG. 8 is performed for each main routine of the control unit 2A, for example, 20 mSEC.
It is calculated repeatedly every time. In S203, | L
If T-LTi |> LL1 is determined and "NO", it means that the fuel fluctuation in the fuel tank is small, that is, the pressure fluctuation in the evaporative fuel control device (evaporation system) is not the influence of the rough road, and S127 is performed. When the detection is completed, it is determined that the vehicle is traveling on a normal road, and the routine returns to execute misfire detection. On the other hand, S2
03, | LT−LTi |> LL1 is determined and “Ye
In the case of "s", it means that the fuel fluctuation in the fuel tank is large, that is, the pressure fluctuation in the evaporative fuel control device (evaporation system) is the effect of a bad road, and the vehicle is currently running on a bad road in S204. In step S301, misfire detection is prohibited (the wheel rotation is unstable on a bad road = the engine rotation is unstable), and the process returns.
Performs the failure detection operation based on the flow of FIGS. 2, 3, and 7, and executes the optimal control of the ignition system and the misfire detection operation based on the flow of FIGS. According to the above-described embodiment of the misfire detection device, even when the engine speed fluctuates due to running on a rough road, misfire detection can be performed more reliably without erroneous detection of misfire.

[Brief description of the drawings]

FIG. 1 is a first embodiment of a failure detection device according to the present invention;
FIG.

FIG. 2 is a flowchart of a failure detection process according to the first embodiment.

FIG. 3 is a flowchart of a failure detection process according to the first embodiment.

FIG. 4 is an operation explanatory diagram according to the first embodiment.

FIG. 5 is an operation explanatory diagram according to the first embodiment.

FIG. 6 is a second embodiment of the failure detection device according to the present invention;
FIG. 2 is a configuration diagram illustrating a form of a misfire detection device.

FIG. 7 is a failure detection processing flowchart according to a second embodiment of the failure detection device.

FIG. 8 is a flowchart of a misfire detection prohibition process in the form of a misfire detection device.

FIG. 9 is a configuration diagram illustrating an example of a conventional failure detection device.

FIG. 10 is a diagram showing the operation of a conventional failure detection device.

[Explanation of symbols]

2, 2A control unit (control means), 8 rotation speed detection sensor, 10 fuel tank, 11 canister, 16
Pressure detection sensor, 19 purge control valve, 20 canister close valve, 21 fuel amount detection sensor.

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 37/00 F02D 41/22 301 F02D 45/00 345 F02D 45/00 368

Claims (3)

(57) [Claims] 1. An evaporation source for fuel of an internal combustion engine, a canister for adsorbing and trapping evaporated fuel generated by the evaporation source, and a control unit for controlling supply of the fuel adsorbed and collected by the canister to the internal combustion engine. A failure detection device for an evaporative fuel control device, comprising: a purge control valve; and a canister close valve that closes an open end of the canister to the atmosphere, wherein the pressure detection detects an internal pressure in a system of the evaporative fuel control device. A sensor, and control means, wherein the control means controls the operation of the purge control valve after closing the canister close valve, and after a lapse of a predetermined time,
The purge control valve is stopped after the
Open the stak rose valve and read the output value of the pressure detection sensor.
Raise to near atmospheric pressure and then close the canister
When it is determined that the output value of the pressure detection sensor is greater than a predetermined value after a lapse of a predetermined time from closing the evaporative fuel control of the internal combustion engine, Device failure detection device. 2. An evaporation source for the fuel of the internal combustion engine, a canister for adsorbing and collecting the evaporated fuel generated by the evaporation source, and a supply for controlling the supply of the fuel adsorbed and collected by the canister to the internal combustion engine. A failure detection device for an evaporative fuel control device, comprising: a purge control valve; and a canister close valve that closes an open end of the canister to the atmosphere, wherein a fuel amount detection sensor for detecting a fuel amount of the evaporation source; Means, when the control means determines that the fluctuation amount of the output value from the fuel amount detection sensor is larger than a predetermined value, stops the failure detection of the evaporative fuel control device. Failure detection device for evaporative fuel control device of internal combustion engine. 3. A cycle of a signal output from a rotation speed detection sensor for detecting a rotation speed of the internal combustion engine is calculated, and a predicted value of a cycle of a signal output next time is obtained. A misfire detection device for an internal combustion engine that performs misfire detection based on a difference between the value and a fuel amount detection sensor that detects a fuel amount of an evaporation source of fuel of the internal combustion engine; and a control unit. A misfire detection device for an internal combustion engine, wherein the misfire detection is prohibited when it is determined that the variation of the output value of the fuel amount detection sensor is larger than a predetermined value.