JP3572383B2 - Failure detection device for variable valve engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a failure detection device for a variable valve engine including an electromagnetically driven intake / exhaust valve and a throttle valve.
[0002]
[Prior art]
2. Description of the Related Art As a conventional variable valve engine failure detection device, as disclosed in Japanese Patent Application Laid-Open No. 2-308913, there is a device that detects an absolute value of an intake pipe pressure and determines a failure when the pressure exceeds a predetermined value. . This is based on the fact that the suction negative pressure (intake pipe pressure) changes depending on the residual gas ratio in a region where the engine suction negative pressure is large. In particular, the residual gas changes depending on the magnitude of the valve overlap. it can.
[0003]
[Problems to be solved by the invention]
However, in such a conventional variable valve engine failure detection device, (1) it is likely to be erroneously detected due to the influence of temperature and atmospheric pressure. (2) Detection sensitivity other than valve overlap is small, and other failures are difficult to detect. (3) If a failure occurs only in a specific cylinder, the sensitivity is low and it is difficult to detect the failure. (4) Since it is greatly affected by the throttle opening, it cannot be detected other than at idle, and even at idle, it is easy to make an erroneous detection due to the effects of friction and auxiliary equipment loads.
[0004]
The present invention has been made in view of such conventional problems, and has as its object to enable a failure of an electromagnetically driven intake / exhaust valve in a variable valve engine to be accurately detected.
[0005]
[Means for Solving the Problems]
Therefore, according to the first aspect of the present invention, in a variable valve engine having an electromagnetically driven intake / exhaust valve and a throttle valve, as shown in FIG. 1, a signal from a pressure sensor for detecting an intake pipe pressure is provided. and based on the signal from the crank angle sensor, a variation state of the intake pipe pressure, a first pressure fluctuation detecting means for detecting the variation range of the intake pipe pressure at the crank angle periods 720 ° CA / number of cylinders, detection A first failure determination means for determining whether or not there is an intake valve opening failure based on the variation range of the intake pipe pressure thus configured, to configure a failure detection device for a variable valve engine.
[0006]
According to a second aspect of the present invention, in a variable valve engine having an electromagnetically driven intake / exhaust valve and a throttle valve, a signal from a pressure sensor for detecting an intake pipe pressure and a crank angle are provided as shown in FIG. Based on the signal from the sensor, the average value of the intake pipe pressure is calculated for each crank angle period of 720 ° CA / cylinder as a variation state of the intake pipe pressure, and the variation range of these average values is detected. A second pressure fluctuation detecting means for determining at least one of an intake valve closing failure, an exhaust valve opening failure, and an exhaust valve closing failure based on the fluctuation width of the detected average value of the intake pipe pressure; And a failure determination means of the present invention are provided to constitute a failure detection device for a variable valve engine.
According to the third aspect of the present invention, in a variable valve engine having an electromagnetically driven intake / exhaust valve and a throttle valve, based on a signal from a pressure sensor for detecting intake pipe pressure and a signal from a crank angle sensor. The first pressure fluctuation detecting means for detecting the fluctuation width of the intake pipe pressure during the crank angle period of 720 ° CA / cylinder as the fluctuation state of the intake pipe pressure, and the fluctuation width of the detected intake pipe pressure. A first failure determination unit that determines whether there is an intake valve opening failure; and a signal from a pressure sensor that detects intake pipe pressure and a signal from a crank angle sensor. A second pressure fluctuation detecting means for calculating an average value of the intake pipe pressure for each crank angle period of 720 ° CA / cylinder number and detecting a fluctuation range of the average value; and an average value of the detected intake pipe pressure. At least one of an intake valve closing fault, an exhaust valve opening fault, and an exhaust valve closing fault based on the fluctuation range of the variable valve engine. Configure the device.
[0007]
According to the fourth aspect of the present invention, there is provided a diagnostic condition determining means for determining, as a diagnostic condition, at least a region in which the intake pipe negative pressure is secured by the throttle valve. It is characterized by performing a failure determination.
[0008]
【The invention's effect】
According to the first to third aspects of the present invention, the fluctuation state of the intake pipe pressure is detected using the pressure sensor for detecting the intake pipe pressure and the crank angle sensor, and the failure of the intake and exhaust valves is detected based on the detected state. By determining the presence / absence, highly accurate failure determination can be performed, and erroneous diagnosis can be prevented.
Further, a failure can be determined without using a special sensor such as a lift sensor or a seat sensor, and diagnosis for multiple cylinders can be performed with one pressure sensor.
[0009]
In particular , according to the first and third aspects of the present invention, the variation of the intake pipe pressure is detected as a variation state of the intake pipe pressure and is compared with a determination level by detecting a variation width of the intake pipe pressure during a predetermined crank angle period. Open faults (failures when left open) can be reliably detected.
In particular , according to the second and third aspects of the present invention, the average value of the intake pipe pressure is calculated every predetermined crank angle period as the fluctuation state of the intake pipe pressure, and the fluctuation range of these average values is detected. Then, by comparing with the determination level, it is possible to reliably detect the intake valve closing failure (failure with the valve closed), the exhaust valve opening failure, and the closing failure.
[0010]
According to the fourth aspect of the present invention, by performing the failure determination in the region where the intake pipe negative pressure is secured by the throttle valve, it is possible to prevent erroneous diagnosis when the throttle with a small pressure fluctuation is fully opened.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS.
FIG. 2 is a system diagram of a variable valve engine showing one embodiment of the present invention.
A combustion chamber 3 defined by a piston 2 of each cylinder of the engine 1 is provided with an electromagnetically driven intake valve 5 and an exhaust valve 6 so as to surround an ignition plug 4. 7, an intake passage; and 8, an exhaust passage.
[0012]
FIG. 3 shows a basic structure of an electromagnetic driving device (variable valve operating device) for the intake valve 5 and the exhaust valve 6. A plate-shaped mover 22 is attached to a valve shaft 21 of the valve body 20, and the mover 22 is urged to a neutral position by springs 23 and 24. The valve opening electromagnetic coil 25 is disposed below the movable element 22, and the valve closing electromagnetic coil 26 is disposed above the movable element 22.
[0013]
Therefore, when the valve is opened, the power supply to the upper valve closing electromagnetic coil 26 is stopped, and then the current is supplied to the lower valve opening electromagnetic coil 25 to attract the movable element 22 to the lower side. The valve body 20 is lifted to open the valve. Conversely, when closing the valve, the power supply to the lower valve-opening electromagnetic coil 25 is stopped, and then the current is supplied to the upper valve-closing electromagnetic coil 26 to attract the mover 22 upward. The valve body 20 is seated on the seat and closed.
[0014]
Returning to FIG. 2, in the intake passage 7, an electrically controlled throttle valve (intake throttle valve) 9 is provided in a common portion common to all cylinders.
The intake passage 7 is also provided with an electromagnetic fuel injection valve 10 at an intake port portion for each cylinder.
Here, the operations of the intake valve 5, the exhaust valve 6, the electronically controlled throttle valve 9, the fuel injection valve 10, and the spark plug 4 are controlled by a control unit 11, and the control unit 11 A crank angle sensor 12 capable of detecting an engine speed Ne together with a crank angle position by outputting an angle signal, an accelerator pedal sensor 13 detecting an accelerator opening (depression amount of an accelerator pedal) APO, a throttle valve 9 in the intake passage 7 An air flow meter 14 for detecting the intake air amount Qa upstream, a throttle sensor 15 for detecting the opening TVO of the throttle valve 9, and an intake pipe pressure (absolute pressure in the intake pipe) MAP downstream of the throttle valve 9 in the intake passage 7. A signal is input from the pressure sensor 16 or the like for detection.
[0015]
In the engine 1, in order to improve fuel efficiency by reducing pump loss, the valve timing of the electromagnetically driven intake valve 5 and the exhaust valve 6 is controlled, and particularly, the closing timing (IVC) of the intake valve 5 is early closed to control the intake. The air amount is controlled to perform the substantially non-throttle operation. In this case, the electronically controlled throttle valve 9 is provided for obtaining a negative pressure in the intake passage 7 under predetermined engine operating conditions.
[0016]
More specifically, the opening timing (IVO) of the intake valve 5 is set at a substantially constant timing near the exhaust top dead center (TDC), and the closing timing (IVC) of the intake valve 5 is determined by the accelerator opening APO and the engine speed Ne. Control is performed in consideration of the throttle opening TVO and / or the intake pipe pressure MAP according to a target air amount corresponding to a target torque determined based on the target air amount.
The opening timing (EVO) and closing timing (EVC) of the exhaust valve 6 are controlled so as to be the timing having the highest thermal efficiency.
[0017]
The fuel injection timing and the fuel injection amount of the fuel injection valve 10 are controlled based on the engine operating conditions. The fuel injection amount is basically controlled based on the intake air amount Qa detected by the air flow meter 14. Is controlled so that the air-fuel ratio becomes.
The ignition timing of the ignition plug 4 is controlled to the MBT or knock limit based on the engine operating conditions.
[0018]
Next, failure detection of the variable valve apparatus (the electromagnetically driven intake valve 5 and the exhaust valve 6) will be described with reference to a flowchart.
FIG. 4 is a main flow of the failure detection, which is executed as a 1 ms job.
In step 1 (referred to as S1 in the figure, the same applies hereinafter), the output voltage of the pressure sensor 16 is read and A / D converted to detect the intake pipe pressure MAP.
[0019]
In step 2, it is determined whether the timing is 720 ° CA / the number of cylinders, that is, in the case of four cylinders, whether the timing is every 180 ° CA or not. If NO, the process proceeds to steps 3 to 6.
In step 3, the maximum value MAPmax of the intake pipe pressure MAP between 180 ° CA is detected. Specifically, for the first time, the detected intake pipe pressure MAP is directly used as the maximum value MAPmax (MAPmax = MAP), and thereafter, the maximum value MAPmax stored and held and the newly detected intake pipe pressure MAP are used. Are compared, and when the newly detected intake pipe pressure MAP is larger, the maximum value MAPmax = MAP is updated.
[0020]
In step 4, the minimum value MAPmin of the intake pipe pressure MAP between 180 ° CA is detected. Specifically, for the first time, the detected intake pipe pressure MAP is directly set to the minimum value MAPmin (MAPmin = MAP), and thereafter, the minimum value MAPmin stored and held and the newly detected intake pipe pressure MAP are set. Are compared, and when the newly detected intake pipe pressure MAP is smaller, the minimum value MAPmin = MAP is updated.
[0021]
In step 5, the intake pipe pressure MAP is integrated for calculating the average value, and the integrated value SMAP is obtained (SMAP = SMAP + MAP).
In step 6, the counter CNT indicating the number of times of integration is incremented by 1 (CNT = CNT + 1). Thus, the process ends.
If the timing is for every 180 ° CA, the process proceeds to step 7 and subsequent steps.
[0022]
In step 7, based on the maximum value MAPmax and the minimum value MAPmin of the intake pipe pressure MAP between 180 ° CA, a variation width (amplitude) A = MAPmax−MAPmin of the intake pipe pressure MAP between 180 ° CA is calculated. I do.
In step 8, a first failure determination (amplitude A determination) is performed based on the amplitude A according to the flow of FIG. This will be described later.
[0023]
In step 9, cylinder discrimination is performed and n is set to one of 1 to 4 (in the case of four cylinders).
In step 10, an average value AMAP = SMAP / CNT of the intake pipe pressure MAP between 180 ° CA is calculated from the integrated value SMAP of the intake pipe pressure MAP between 180 ° CA and the integrated number CNT.
[0024]
In step 11, the calculated intake pipe pressure average value AMAP is stored and held for each cylinder (n = 1 to 4) (AMAPn = AMAP).
In step 12, the difference B between the maximum value and the minimum value among the average values of the intake pipe pressures AMAP1 to AMAP4 for each cylinder is calculated as in the following equation, and the fluctuation width B of AMAP1 to AMAP4 is calculated.
[0025]
B = MAX (AMAP1 to AMAP4) -MIN (AMAP1 to AMAP4)
In step 13, a second failure determination (average value variation B determination) is performed based on the variation B of AMAP1 to AMAP4 according to the flow of FIG. This will be described later.
In step 14, the integrated value SMAP and the integrated number CNT are cleared, and the process ends.
[0026]
Here, the step 7 (and 3, 4) corresponds to the first pressure fluctuation detecting means, and the step 8 corresponds to the first failure determining means. Steps 9 to 12 (and 5, 6) correspond to second pressure fluctuation detecting means, and step 13 corresponds to second failure detecting means.
FIG. 5 is a first failure determination (amplitude A determination) flow.
[0027]
In step 21, it is determined whether or not a predetermined diagnosis condition is satisfied. This part corresponds to diagnostic condition determination means. Here, the predetermined diagnosis condition is that all of the following (1) to (3) are satisfied.
(1) The throttle opening TVO is equal to or smaller than a threshold TVOSL proportionally allocated according to the engine speed Ne (TVO ≦ TVOSL). This is because the condition is that there is a negative pressure in the intake pipe.
[0028]
(2) The absolute value ΔAPO of the change amount of the accelerator opening APO is equal to or less than a predetermined value (ΔAPO ≦ predetermined value). This is to avoid transient operation.
(3) The absolute value ΔNe of the variation of the engine speed Ne is equal to or less than a predetermined value (ΔNe ≦ predetermined value). This is to avoid transient operation.
If the diagnosis condition is not satisfied, the flow ends, and if the diagnosis condition is satisfied, the process proceeds to step 22.
[0029]
In step 22, the fluctuation width (amplitude) A of the intake pipe pressure MAP between 180 ° CA is compared with a predetermined determination level.
As a result of the comparison, if A <determination level, it is regarded as normal, and the counter OK1 is incremented by one in step 23 (OK1 = OK1 + 1).
On the other hand, if A ≧ determination level, it is regarded as a failure, and the counter NG1 is incremented by 1 in step 24 (NG1 = NG1 + 1).
[0030]
In step 25, it is determined whether or not the number of samples is OK, that is, whether the number of samples, which is the sum of OK1 and NG1, is equal to or greater than a predetermined value.
If the number of samples (OK1 + NG1) is equal to or larger than the predetermined value, the process proceeds to step S26.
In step 26, the ratio of NG1 to OK1 (NG1 / OK1) is compared with a predetermined value NG1 #.
[0031]
As a result of the comparison, if NG1 / OK1 <NG1 #, it is finally regarded as normal, the counters OK1 and NG1 are cleared in step 28, and this flow ends.
On the other hand, if NG1 / OK1 ≧ NG1 #, it is finally determined that a failure has occurred in step 27 (NG1 determination), the counters OK1 and NG1 are cleared in step 28, and this flow ends.
[0032]
FIG. 6 is a flow of the second failure determination (average value variation width B determination) flow.
In step 31, it is determined whether or not a predetermined diagnostic condition is satisfied. This part corresponds to diagnostic condition determination means. The diagnostic conditions are the same as the conditions in step 21 of FIG.
If the diagnosis condition is not satisfied, the flow ends, and if the diagnosis condition is satisfied, the process proceeds to step 32.
[0033]
In step 32, the variation width B of the average intake pipe pressure values AMAP1 to AMAP4 between the cylinders is compared with a predetermined determination level.
If B <determination level as a result of the comparison, it is regarded as normal, and the counter OK2 is incremented by 1 in step 33 (OK2 = OK2 + 1).
On the other hand, if B ≧ determination level, it is regarded as a failure, and the counter NG2 is incremented by 1 in step 34 (NG2 = NG2 + 1).
[0034]
In step 35, it is determined whether or not the number of samples is OK, that is, the number of samples, which is the sum of OK2 and NG2, is equal to or greater than a predetermined value.
If the number of samples (OK2 + NG2) is equal to or larger than the predetermined value, the process proceeds to step S36.
In step 36, the ratio of NG2 to OK2 (NG2 / OK2) is compared with a predetermined value NG2 #.
[0035]
As a result of the comparison, if NG2 / OK2 <NG2 #, it is finally regarded as normal, the counters OK2 and NG2 are cleared in step 38, and this flow ends.
On the other hand, if NG2 / OK2 ≧ NG2 #, it is finally determined that a failure has occurred in step 37 (NG2 determination), the counters OK2 and NG2 are cleared in step 38, and this flow is terminated.
[0036]
Note that, when the NG1 determination is made in step 27 of the first failure determination flow in FIG. 5, or when the NG2 determination is made in step 28 of the second failure determination flow in FIG. Then, the process proceeds to a predetermined fail-safe process.
Next, failure determination for various failure modes will be described with reference to the schematic diagram of FIG.
[0037]
In the case where the intake valves of each cylinder are controlled to be closed early, the intake pipe pressure MAP decreases during a normal period of the intake valve opening period in each cycle, and increases when the intake valve is closed.
Failure mode (1): Intake valve open failure If, for example, the intake valve of cylinder # 1 opens (failure while opening), the behavior of the piston of cylinder # 1 is reflected almost directly on the intake pipe pressure MAP, and cylinder # 1 During the intake stroke, the intake pipe pressure MAP greatly decreases, and during the compression stroke, the intake pipe pressure MAP greatly increases. Therefore, the fluctuation width (amplitude) A of the intake pipe pressure MAP between 180 ° CA becomes large, and thereby a failure is detected.
[0038]
Failure mode (2): Intake valve closing failure If, for example, the intake valve of the # 3 cylinder closes (failure while being closed), the intake pipe pressure MAP does not decrease but increases in the intake stroke of the # 3 cylinder. At this time, the intake pipe pressure average value AMAP3 increases. Therefore, the fluctuation width B of the average value of the intake pipe pressure between the cylinders becomes large, whereby a failure is detected.
[0039]
Failure mode (3): Exhaust valve open failure For example, if the exhaust valve of cylinder # 3 opens (fails while it remains open), the exhaust valve opens when the intake valve opens in the intake stroke of cylinder # 3. Therefore, the exhaust gas flows backward, and the intake pipe pressure MAP does not decrease but rises, so that the intake pipe pressure average value AMAP3 at this time increases. Therefore, the fluctuation width B of the average value of the intake pipe pressure between the cylinders becomes large, whereby a failure is detected.
[0040]
Failure mode (4): Exhaust valve closing failure For example, if the exhaust valve of the # 3 cylinder closes (fails when it is left closed), the gas in the cylinder of the # 3 cylinder immediately before the intake valve of the # 3 cylinder opens. Is not discharged, and when the intake valve of the # 3 cylinder is opened, the high-pressure gas in the cylinder flows backward, and the intake pipe pressure MAP does not decrease but rises. The average value AMAP3 increases. Therefore, the fluctuation width B of the average value of the intake pipe pressure between the cylinders becomes large, whereby a failure is detected.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing the configuration of the present invention. FIG. 2 is a system diagram of a variable valve engine showing one embodiment of the present invention. FIG. 3 is a basic structural diagram of an electromagnetic drive device for intake and exhaust valves. FIG. 5 is a flowchart of a first failure determination (amplitude A determination). FIG. 6 is a flowchart of a second failure determination (average value fluctuation width B determination). FIG. 7 is an intake at various failures. Schematic diagram showing pipe pressure fluctuations [Explanation of symbols]
Reference Signs List 1 engine 4 ignition plug 5 electromagnetically driven intake valve 6 electromagnetically driven exhaust valve 9 electrically controlled throttle valve 10 fuel injection valve 11 control unit 12 crank angle sensor 13 accelerator pedal sensor 14 air flow meter 15 throttle sensor 16 pressure sensor

Claims (4)

In a variable valve engine having an electromagnetically driven intake / exhaust valve and a throttle valve,
Based on the signal from the pressure sensor for detecting the intake pipe pressure and the signal from the crank angle sensor , the variation range of the intake pipe pressure during the crank angle period of 720 ° CA / number of cylinders is detected as the variation state of the intake pipe pressure. First pressure fluctuation detecting means for performing
First failure determination means for determining the presence or absence of an intake valve opening failure based on the detected fluctuation width of the intake pipe pressure;
A failure detection device for a variable valve engine, comprising: In a variable valve engine having an electromagnetically driven intake / exhaust valve and a throttle valve,
Based on the signal from the pressure sensor for detecting the intake pipe pressure and the signal from the crank angle sensor , the average value of the intake pipe pressure is set for each crank angle period of 720 ° CA / cylinder as a variation state of the intake pipe pressure. A second pressure fluctuation detecting means for calculating and detecting a fluctuation width of these average values ;
A second failure determination unit configured to determine at least one of an intake valve closing failure, an exhaust valve opening failure, and an exhaust valve closing failure based on a variation range of the detected average value of the intake pipe pressure;
A failure detection device for a variable valve engine, comprising: In a variable valve engine including an electromagnetically driven intake / exhaust valve and a throttle valve,
Based on the signal from the pressure sensor for detecting the intake pipe pressure and the signal from the crank angle sensor, the variation range of the intake pipe pressure during the crank angle period of 720 ° CA / cylinder is detected as the variation state of the intake pipe pressure. A first pressure fluctuation detecting means,
First failure determination means for determining the presence or absence of an intake valve opening failure based on the detected fluctuation width of the intake pipe pressure;
Based on the signal from the pressure sensor for detecting the intake pipe pressure and the signal from the crank angle sensor, the average value of the intake pipe pressure is set for each crank angle period of 720 ° CA / cylinder as a variation state of the intake pipe pressure. A second pressure fluctuation detecting means for calculating and detecting a fluctuation width of these average values;
A second failure determination unit configured to determine at least one of an intake valve closing failure, an exhaust valve opening failure, and an exhaust valve closing failure based on a variation range of the detected average value of the intake pipe pressure;
A failure detection device for a variable valve engine, comprising: Diagnosis condition determining means for determining as a diagnostic condition that at least the region where the intake pipe negative pressure is secured by the throttle valve is provided, and the failure determination by the failure determination means is performed only when the diagnostic condition is satisfied. The variable valve engine failure detection device according to any one of claims 1 to 3.

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