JP2000192845A - Intake air flow control device for engine provided with diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diagnose failure at low cost and with high accuracy by diagnosing failure or an auxiliary air control valve comparing a real intake air rate found out by a detecting means and a calculated intake air flow with each other, in a device wherein the auxiliary air control valve is controlled on the basis of an output signal of an intake air flow calculating means. SOLUTION: Means 61 for detecting each operating condition of an engine on the basis of a detecting signal of several kinds of sensors is disposed on an intake air flow control device 13, and target rotating speed of the engine is set 65 on the basis of the detected value. Real rotating speed is detected 65 from a value detected by a rotation angle sensor 23, and a real intake flow is calculated 67 from values detected by an air rate sensor 20 and a pressure sensor 28. Target rotating speed, a basic air flow calculated 62 on the basis of an engine cooling water temperature and the like, a deviation between the target rotating speed and the real rotating speed, and the other correcting object are taken into consideration to correct a basic air flow 63. The obtained intake air flow and the real intake flow are compared with each other by a failure diagnostic device 68 so as to diagnose an auxiliary air control valve 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air amount control device for an engine provided with a diagnostic device, and more particularly to an auxiliary intake passage which bypasses a throttle valve of an intake pipe.
The present invention relates to an intake air amount control device for an engine including a self-diagnosis device that diagnoses an operation state of an auxiliary air control valve that controls an idle state.

[0002]

2. Description of the Related Art Conventionally, an auxiliary air control valve is provided in an auxiliary intake passage that bypasses a throttle valve of an intake pipe in order to match an idle speed of an engine with a target speed set according to an operating state of the engine. There has been proposed an intake air control device for an engine which is mounted and controls the amount of auxiliary air by changing the opening area of the auxiliary air control valve. Various means have been proposed for controlling the auxiliary air control valve.
The auxiliary air control valve is provided with a stepping motor driven by a multi-phase excitation signal, and by controlling the stepping motor, a valve (valve) of the auxiliary air control valve is provided.
A stepping motor type auxiliary air control valve for adjusting the opening degree has been adopted.

The drive control by the stepping motor is as follows:
For example, if the driving excitation phase of the stepping motor is four phases, as shown in FIG. 10, a large number of patterns are prepared, and the excitation pattern of the excitation phase is changed by selecting the patterns, so that the auxiliary air control valve is used. Is driving the valve. However, if the supply of the excitation signal to some of the phases is stopped due to the disconnection of the stepping motor or the like, even if the control device outputs the signal to the stepping motor, the excitation state of the control device is not intended. As a result, a state such as a delay in valve control speed, an operation stop, a reverse rotation, or the like may occur, and a problem such as an abnormally high rotation of the engine, an abnormal decrease, or engine stall may occur.

As a preventive measure in the case of occurrence of such an abnormality, it is necessary to immediately identify the cause of the abnormality and implement fail-safe. For example, as shown in FIG. A control device for controlling the supply of the excitation signal to the motor, a diagnostic circuit for detecting a disconnection of the signal line is provided, and a device having a function of stopping the supply of the excitation signal for all phases when an abnormality is detected. Has been proposed.

As described above, the control device needs to include a special abnormality detection and diagnosis circuit (see FIG. 11) in order to detect an abnormality in the signal line of the stepping motor. In the abnormality detection and diagnosis circuit, as a detection means corresponding to one phase of the stepping motor, an excitation signal (current) of the coil L1 of the stepping motor is switched by turning on and off the output transistor T1. When the drive signal So is at a high level, the transistor T1
N, and the output voltage becomes Low level. That is, if the signal line is normal, the drive signal So and the output voltage monitor signal Sm have a reverse transmission relationship in which one is at a high level and the other is at a low level, as shown in FIG. Here, for example, when a disconnection occurs between the signal lines Pa-Pb, the output monitor signal Sm thereafter becomes a constant Low level as shown in FIG. When the control device detects that the drive signal So and the output voltage monitor signal Sm do not have opposite phases, the control device takes measures to cut off the exciting currents of all the phases of the stepping motor and determines that the stepping motor has failed. Then, a failure treatment (for example, recognition of a failure by a driver, registration in a failure history storage unit of the control device, and the like) is performed.

[0006]

The abnormality detection and diagnosis circuit requires a dedicated output signal monitoring means in the control device and requires a number of input circuits corresponding to each excitation phase. There is a problem that the device becomes expensive. The determination of the failure of the stepping motor has been described by taking the drive signal monitor of the stepping motor as an example. However, even in the method of controlling the energization time of the electromagnetic mechanism by changing the energization time rate (Duty), the drive current of the electromagnetic mechanism is also determined. , The failure is detected, and in this case, there is the same problem as described above.

[0007] As a countermeasure for solving the above-mentioned problem, the engine intake air amount is detected in an idle state in which the throttle valve is fully closed in which only the auxiliary air control valve is opened, and it is determined whether or not the detected value is an appropriate value. There has been proposed a diagnostic device that makes a determination or a diagnostic device that intentionally changes the opening area of the auxiliary air control valve in an idle state and checks the amount of change in the intake air amount as a response result.

For example, in the technology described in Japanese Patent Application Laid-Open No. 7-97952, a stable idle state is detected, and the amount of change in suction in the stable state is compared with a predetermined value. When it exceeds, it is determined that the intake air amount control device (idling speed control device) is abnormal. However, in the self-diagnosis of the intake air amount control device (idle rotation speed control device) that controls the idle state, if there is an abnormality in the intake air amount control device (idle rotation speed control device), it is not necessarily assumed that a stable idle state exists. Since it cannot be said, the above-mentioned technique may cause a problem that the diagnosis condition is not satisfied from the beginning because the diagnosis target device is abnormal.

Further, the technique described in Japanese Patent Application Laid-Open No. Hei 7-133740 has a forced opening / closing means for changing an auxiliary air control valve in a predetermined mode, and the amount of change in intake air when the mode is changed is determined. If the change amount of the intake air is smaller than the predetermined value, the abnormality of the auxiliary air control valve is determined. However, the means for forcibly opening and closing the auxiliary air control valve for diagnosis has a problem that the idling performance is reduced. Further, the diagnosis based on the change amount of the intake air amount is performed, for example, when the intake air amount fluctuates due to torque fluctuation due to misfiring at the time of rare frequency misfiring due to abnormality of the ignition control device. A great deal of man-hour is required for the extraction and the setting of the threshold value of the amount of change in the intake air. Further, if another failure acts in a direction to cancel the change in the intake air amount due to the failure of the intake air amount control device (idle speed control device), there is a problem that the diagnostic accuracy is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a dedicated diagnosis for a failure diagnosis of an intake air amount control device for an engine having an auxiliary air control valve. Equipped with a diagnostic device that can accurately diagnose faults inexpensively and in a short time without requiring a circuit and without disturbing the idle control state while maintaining the configuration of the existing control device. An object of the present invention is to provide an intake air amount control device for an engine.

[0011]

In order to achieve the above object,
The intake air amount control device provided with the diagnostic device of the present invention basically includes a means for detecting an operation state of an engine, and a means for calculating an intake air amount based on an output signal of the operation state detection means. The invention is applied to an engine that controls an auxiliary air control valve that circulates auxiliary air by bypassing a throttle valve based on an output signal of the intake air amount calculation means. Means for calculating the actual intake air amount of the intake air, and auxiliary air control valve failure diagnosing means. The auxiliary air control valve failure diagnosing means comprises an actual intake air amount calculated by the actual intake air amount calculation means and the intake air amount. The amount of intake air calculated by the amount calculating means is compared, and a failure of the auxiliary air control valve is diagnosed based on the comparison result.

[0012] In another aspect of the intake air amount control device provided with the diagnostic device of the present invention, the intake air amount control device includes means for judging a diagnosis area for failure diagnosis of the auxiliary air control valve. The diagnostic region determining means determines whether the auxiliary air control valve failure diagnostic means has permitted diagnosis, interrupted diagnosis, or discarded the diagnosis result, and the intake air amount control device determines an operating state of the engine. Means, wherein the diagnostic area determining means determines a diagnostic area based on a determination result of the operating state determining means, and further wherein the intake air amount control device includes timer means and / or engine rotation angle detection. Means for setting a predetermined delay period based on an output signal of the timer means or the engine rotation angle detecting means when diagnosis is permitted. .

The intake air amount control device provided with the diagnostic device of the present invention having the above-described structure is characterized in that the actual intake air amount calculated by the actual intake air amount calculation means and the intake air amount calculated by the intake air amount calculation means are calculated. And the failure of the auxiliary air control valve is diagnosed based on the comparison result, so that a special dedicated diagnosis circuit is not required, and the auxiliary air control valve is configured with the existing control device. Valve failures can be diagnosed.

Further, there is provided means for judging an area for diagnosing the failure, and the judgment of the diagnosing area is determined based on an operation state of the engine, so that the auxiliary air control valve is operated only in a specific operation state. Because it was configured to diagnose failures,
It is possible to diagnose a failure of the auxiliary air control valve with high accuracy without erroneous determination. Further, a predetermined delay period is set based on an output signal of the timer means or the engine rotation angle detecting means, so that an engine negative pressure or the like which is one of the detections of the operating state of the engine is estimated. In this case, when it is necessary to consider the convergence delay time of the actual negative pressure due to the volume of the negative pressure system pipe length of the engine, the accuracy of failure diagnosis can be improved.

[0015] In another specific embodiment of the intake air amount control device provided with the diagnostic device of the present invention, the auxiliary air control valve failure diagnosing means includes: an intake air amount calculated by the intake air amount calculating means; Calculating a difference amount from the actual intake air amount calculated by the intake air amount calculation means, and comparing the difference amount with a failure determination value for diagnosis, wherein the failure determination value is calculated by the intake air amount calculated by the intake air amount calculation means. Means for setting according to the amount of air (atmospheric pressure, the amount of intake air after correction of the intake air temperature), and means for setting the target rotational speed based on the output signal of the operation state detecting means, And a basic air amount calculating means, wherein the intake air amount calculating means corrects the basic intake air amount calculated by the basic air amount calculating means by matching the calculated target rotational speed with the actual rotational speed. It is characterized by.

In another specific aspect of the intake air amount control device provided with the diagnostic device of the present invention, the operating state determining means calculates an engine load based on the actual intake air amount and the actual rotation speed. And at least one of an atmospheric pressure condition judging device, an intake air temperature condition judging device, and an intake pipe negative pressure detecting device.

Still another specific embodiment of the intake air amount control device provided with the diagnostic device of the present invention is characterized in that the intake air amount control device comprises an atmospheric pressure detecting means or an atmospheric pressure estimating means, an atmospheric pressure correcting means, Means for correcting the atmospheric pressure, wherein any of the intake air amount calculated by the intake air amount calculating means, the difference amount, or the failure determination value is output from the atmospheric pressure detecting means or the atmospheric pressure estimating means. Signal, and the intake air amount control device includes intake air temperature detecting means or intake air temperature estimating means and intake air temperature correcting means, and the intake air temperature correcting means is an intake air amount calculating means. One of the calculated intake air amount, the difference amount, and the failure determination value is corrected by an output signal of the intake air temperature detecting means or the intake air temperature estimating means.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an intake air amount control device for an engine provided with a diagnostic device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall configuration diagram of an engine system including an intake air amount control device of the present embodiment. The engine 50 includes a cylinder 16, a cylinder head 7, and a piston 2 reciprocating in the cylinder 16.
The cylinder head 7 has an intake branch pipe 5
And an exhaust pipe branch pipe 10, and an intake valve 6 and an exhaust valve 9 are provided.

In the air supply system, the air cleaner 1
The air flow is controlled by a throttle valve 3 provided in a throttle body 2 and supplied to a combustion chamber 8 of an engine 50 via a surge tank 4, the intake branch pipe 5, and an intake valve 6. You. Throttle body 2
Is provided with an air passage 5a bypassing the throttle valve 3, and an auxiliary air control valve 12 is mounted in the air passage 5a. The auxiliary air control valve 12 is driven by a stepping motor. The auxiliary air control valve 12 may have a structure mounted separately from the throttle body 2 via a conduit from the intake passage. The product gas burned in the combustion chamber 8 is discharged to the atmosphere via the exhaust valve 9 and the exhaust branch pipe 10.

In the fuel supply system, a fuel injection valve 11 is disposed in the intake branch pipe 5 with its injection port facing the combustion chamber 8.
The fuel injection valve 11 is connected to the fuel passage 30 from the fuel tank 30.
The fuel is pumped by the pump 26 through 6. The exhaust branch pipe 10 is equipped with an oxygen sensor 14 for detecting the oxygen concentration in the exhaust gas, and the intake branch pipe 5 is provided with a throttle sensor 15 for detecting the rotation angle of the throttle valve 3 and an intake pressure sensor 28. And water jacket 1
6a, a water temperature sensor 17 is attached, and the air cleaner 1
Is mounted with an intake air temperature sensor 18 for detecting the intake air temperature and an air amount sensor 20 for detecting the amount of intake air.

An engine 50 has an atmospheric pressure sensor 19 for detecting atmospheric pressure, and a crankshaft (not shown) connected to a piston 21 via a connecting rod 22.
A rotation angle sensor 23 for detecting the rotation speed of the vehicle, a vehicle speed sensor 24 for detecting the vehicle speed, and the like are provided. The rotation angle sensor 23 includes a position detector that generates a pulse once for every two rotations of a crankshaft (not shown), a predetermined crank angle,
For example, an angle detector that generates a pulse every 1 ° is provided. It also receives input signals from the ignition switch 25 and the like.

Control unit (control device) 13
Inputs an output signal from each of the sensors, calculates a fuel injection amount and a fuel injection time, and outputs a fuel injection pulse to the fuel injection valve 11. Further, the control unit (control device) 13 calculates the driving amount of the auxiliary air control valve 12 and drives the auxiliary air control valve 12 according to the number of excitation phases of the stepping motor 42.

FIG. 2 is a block diagram showing the internal configuration of the control unit (control device) 13. The control device 13 includes a microprocessor 32 as an arithmetic unit, a read only memory (ROM) 33, and a random access memory (RAM). ) 34, and input / output device (I / O port)
35 to 38, etc., an oxygen sensor 14, a water temperature sensor 17, an intake air temperature sensor 18, a throttle sensor 15,
The signals of the air amount sensor, the intake pipe pressure sensor 28, etc.
The signal is sent to the A / D converter 29 and converted into a digital signal.

The rotation speed detection circuit 30 is provided with a rotation angle sensor 23.
The number of pulses input within a predetermined time from the angle detector 31 is counted, and a value proportional to the number of rotations is generated. The microprocessor 32 is connected to the ROM 33, the RAM 34, and other blocks 35, 36, and 37, and executes various calculations based on a predetermined program.

The flow rate of the air passing through the intake air supply system of the engine is calculated based on the output of the pressure sensor 28 in the intake pipe, or the air flow sensor 20 of a hot wire type air flow meter or the like installed in the intake passage. The calculation is performed by any means of calculating based on the output of. The drive signal of the auxiliary air control valve 12 to the stepping motor is determined by the result of calculating the number of steps of the stepping motor according to the operating state of the engine.

FIG. 3 is a control block diagram of the intake air amount control device 13 of the engine provided with the diagnostic device of the present embodiment. The intake air amount control device 13 includes an operating state detecting means 61 for detecting each operating state of the engine based on detection signals from various sensors, and a target rotation of the engine based on the detected value of the operating state detecting means 61. A target rotation speed setting means 65 for setting the number of rotations, an actual rotation speed detection means 66 based on the detection value of the rotation angle sensor 23, and an actual intake air amount calculation means 67 based on the detection values of the air amount sensor 20 and the pressure sensor 28. Have.

The drive system of the auxiliary air control valve 12 includes a target rotation speed setting means 65, a basic air amount calculation means 62 for calculating a basic air amount based on an engine cooling water temperature and the like, the target rotation speed and the actual rotation speed. Intake air amount calculating means 63 for correcting the basic air amount in consideration of a deviation from the correction air amount and other correction factors such as other load elements of the engine, and an auxiliary for controlling the auxiliary air control valve 12 based on the corrected air amount. Air control valve control means 64
And

On the other hand, the auxiliary air control valve failure diagnosis system basically comprises auxiliary air control valve failure diagnosis means 68, diagnosis area determination means 69, and engine operating state determination means 70. The auxiliary air control valve failure diagnosis means 68
Diagnoses the auxiliary air control valve 12 by comparing the amount of air calculated by the intake air amount calculating means 63 and the actual intake air amount calculating means 67. Is the engine load condition at the time of diagnosis,
It determines whether the engine is in an idle state, whether it is in an atmospheric pressure state, or whether it is in an intake air temperature state, and outputs the result of the determination to the diagnosis area determining means 69. The diagnostic area determining means 69
Determines whether or not the current operating state of the engine is in the region of the failure diagnosis of the auxiliary air control valve 12 based on the determination result, and outputs the result to the auxiliary air control valve failure diagnosis means 68. The auxiliary air control valve failure diagnosing means 68 performs the failure diagnosis of the auxiliary air control valve 12 only when the operating state of the engine is in the diagnostic region of the auxiliary air control valve 12.

Next, an embodiment of a specific diagnosis control of the engine intake air amount control device 13 provided with the diagnosis device of the present embodiment will be described. The control signal of the auxiliary air control valve 12 of the present embodiment is an air amount Q calculated by the following equation (1).
This is executed by outputting the number of steps corresponding to A.

[0030]

QA = ITW + IFB + ILD + Ik (1)

Here, the air amount QA is an air amount calculated for each operating state of the engine.
TW indicates a basic air amount corresponding to the engine cooling water temperature, and sets a central value necessary to achieve a target idle speed set according to the engine cooling water as shown in FIG. It is. IFB is a feedback amount for controlling an air amount based on a difference between an actual rotation speed and a target rotation speed, and ILD is an element for increasing a required air amount of an engine, for example, an electric device such as a headlight or an air conditioner. The amount of air is set such that the target rotation speed can be maintained even when a load is applied. Ik is set as a correction term of an element that increases the required air amount other than the above.

Then, the air amount QA obtained by the equation (1)
Is given as the number of steps to the stepping motor of the actual auxiliary air control valve. That is, the calculated air amount Q
It is necessary to convert A to the number of steps, and the conversion from the air amount to the number of steps is realized by the conversion table shown in FIG. The horizontal axis in FIG. 5 is the air amount QA, and the air amount QA calculated in the operating state of the engine is converted into the number of steps on the vertical axis, and the converted step number is output to the stepping motor, so that the auxiliary air control valve Changes the opening area. Here, the air amount QA to be handled is a volume flow rate, [m ↑ 3 /
[min].

On the other hand, the actual flow rate of air taken into the engine is measured by the air flow sensor 20. The air amount measured by the air amount sensor 20 is obtained by converting the air amount with respect to the output voltage of the air amount sensor 20 using an air amount table shown in FIG. The air volume handled here is the mass flow rate, [kg /
s]. Next, a situation in which one phase of the auxiliary air control valve 12 is disconnected due to some influence will be described. Here, it is assumed that the auxiliary air amount control valve is fixed at the step position at the time of the disconnection due to the one-phase disconnection.

The number of steps is calculated from the amount of air QA calculated based on the operating state of the engine 50 by converting the amount of air into the number of steps, and is output to the stepping motor 42. If the air amount QA at this time is q in FIG. 5, the number of steps is s. However, due to the one-phase disconnection, the actual stepping motor is fixed at the position of the step number sng. On the other hand, the air amount measured by the air amount sensor 20 detects the air amount in the operating state at that time, outputs the voltage of v in FIG. 6, and detects the qreal air amount.

Here, the air amount qreal and the number of steps s
The air amount qng corresponding to ng substantially matches theoretically.
However, since the dimensions of the air amount qreal and the air amount qng do not match, it is necessary to convert the volume flow rate of the air amount qng into a mass flow rate. This conversion uses the output of the atmospheric pressure sensor 19 and the output of the intake air temperature sensor 18,
It is calculated by the following equation (2).

[0036]

Hqng = qng × k1 (2)

Here, k1 is a correction term for converting the calculated air quantity qng (volume flow rate) sucked through the auxiliary air control valve 12 into a mass flow rate.
In a standard state, it is represented by the following equation (3).

[0038]

Γ = 1.2931 × (273 / (273 + t)) × (H / 760) [kg / m ↑ 3] (3) where t: temperature [° C.], H: pressure [mmHg]

Therefore, by taking the correction term k1 as equation (3) and substituting the intake air temperature and atmospheric pressure by unit conversion,
Hqng is obtained as the mass and weight, and is the same dimension as qreal in FIG. 6, which is the quantity of air measured by the air quantity sensor 20. In this state, Hqng and qrea
By comparing l, values that are essentially the same can be calculated as differences. That is, if the difference is larger than a predetermined value,
The actual air amount is deviated from the air amount that should correspond to the number of steps to the stepping motor. If the air amount sensor 20 is normal, the auxiliary air control valve 12 has somehow failed. It is possible to detect that. Here, the method of matching the dimension to the detection value of the air flow sensor 20 has been described, but the detection value of the air flow sensor 20 is converted from a mass flow rate to a volume flow rate, and The same effect can be obtained by means for adjusting the dimension to the dimension corresponding to the step position of the air control valve 12.

In the above description, the auxiliary air control valve 12
It is assumed that the amount of air taken in at the number of steps and the amount of air detected by the air amount sensor 20 are substantially the same. However, in actuality, there are some mismatch factors between the amount of air detected by the air amount sensor 20 and the amount of air at the auxiliary air control valve 12. The air amount of the auxiliary air control valve 12 is controlled by the throttle valve 3
The air amount detected by the air amount sensor 20 is the amount of intake air other than the auxiliary air control valve 12, for example, the amount of air passing through the throttle valve of the throttle body 2 (the amount of air passing through the throttle valve). (Leak flow rate when closed),
This is because the measurement includes the amount of air from other air control valves. Also included are errors due to measurement errors of the air amount sensor 20 itself, errors due to aging of the sensors, and aging errors due to wear of the auxiliary air control valve seat.

Therefore, in diagnosing a failure of the auxiliary air control valve 12 using the above-mentioned means, the predetermined value (failure determination value) to be compared with the respective differences has a width corresponding to the flow rate based on these error elements. It is necessary to set it.
However, the error component that can be corrected may be included in the above-described diagnostic air difference calculation formula, and the correction may be subtracted from a predetermined value (failure determination value). Predetermined value (failure judgment value) to be compared
Is specifically given as shown in FIG. That is, for the number of steps indicating the opening area of the auxiliary air control valve 12, the threshold value (failure determination value) of the air amount for determining the failure of the auxiliary air control valve 12 is the air amount L1 and the air amount L2 in FIG.
Are represented by the two lines.

Here, the threshold air amounts L1 and L2 are set in accordance with the number of steps because the upper and lower limit control values of the output of the air amount sensor 20 and the auxiliary air control valve under different air flow rates. This is for accurately absorbing the difference between the upper and lower limit values of the control flow rate and the like. However, depending on how to provide the failure criterion, the threshold value (failure criterion value) may be one and the same width in the vertical direction. Further, for example, if only an extreme flow rate abnormality with a danger of runaway is determined, a single threshold value (failure determination value) can be given.

If there is a significant factor in widening the widths of the threshold values L1 and L2 in FIG. 7, it is necessary to control not to perform a failure diagnosis in order to more accurately perform the above-described diagnostic control. is there. That is, it is necessary to provide a means for determining whether to perform the failure diagnosis or not according to conditions such as the atmospheric pressure, the intake temperature, the intake pipe pressure, and the engine rotation speed, which are the operating states of the engine. is there.

In the above case, for example, the number of steps of the drive motor of the auxiliary air control valve 12 is increased and the opening area is increased, so that the upstream (atmospheric pressure side) and downstream (the engine If the differential pressure on the negative pressure side changes and the flow velocity of the air passing through the auxiliary air control valve 12 becomes lower than the sonic speed, there is a problem that the actual amount of air flowing into the engine 50 decreases. In this case, the actual inflow air amount can be corrected by the atmospheric pressure and the engine negative pressure.
Since a measurement error and a measurement delay of these pressures become problems, the diagnosis is prohibited from the viewpoint of securing the diagnosis accuracy.

This is achieved, for example, by monitoring the engine negative pressure,
Diagnosis is prohibited or interrupted based on the pressure difference from the atmospheric pressure. Alternatively, if it takes time to detect the engine negative pressure, control is performed to discard the previous diagnosis result in consideration of the delay. The engine negative pressure can be obtained from the intake air amount, the throttle opening, the supplementary air valve opening, and the engine speed, even when the engine negative pressure cannot be directly detected. However, when estimating the engine negative pressure, it is necessary to consider that there is a delay time in the convergence of the actual negative pressure due to the volume of the pipe length of the negative pressure system of the engine. Similarly, a decrease in the atmospheric pressure when traveling at high altitude can be a similar problem factor, and therefore, monitoring this and using it as a condition for correcting the diagnosis or as to whether or not to perform the diagnosis requires the diagnosis accuracy. Leads to improvement. A similar measure is effective in that the intake air temperature also affects the air mass.

The above can be summarized as diagnostic conditions for the purpose of permitting the diagnosis of the auxiliary air control valve 12 or not. That is, the idle state detection, the engine negative pressure, the engine rotation speed, the atmospheric pressure, the intake air temperature, and the like are monitored as condition parameters for permitting the start of the diagnosis. Further, when it is necessary to consider a delay time such as estimation of the engine negative pressure, a means for giving a delay time to the establishment of each of the above parameters, and a delay time is set after all the diagnosis permission conditions are satisfied, Means for starting the diagnosis after the lapse of the time can also be expected from the viewpoint of improving the diagnosis accuracy. As the delay time, it is also possible to use a rotation angle amount obtained by counting input pulses from the angle detector 31 of the rotation sensor 23 without using a timer of the control device.

In addition, it goes without saying that the conditions for failure diagnosis require the preconditions that the engine operating state detecting means and the air amount sensor are normal. FIG. 8 shows an example of a control flowchart of a failure diagnosis of the auxiliary air control valve 12. The control flowchart of FIG. 7 is started by the management program at regular intervals, for example, every 10 ms.

The program shown in FIG. 8 shows a routine for controlling the normal auxiliary air control valve 12, and the program proceeds to step 100.
Then, the operating state of the engine is read. Specifically, the cooling water temperature of the engine, the intake air temperature, the output of the air amount sensor,
The idle detection signal and the engine speed are read.
In step 110, a target rotation speed corresponding to the cooling water temperature is searched. In step 120, a basic control air amount QA for achieving the target rotation speed is calculated. Here, each correction term of the equation (1) is calculated based on the result of detecting the operating state of the engine. The basic control air amount QA is calculated. In step 130, the previously obtained basic control air amount QA is converted into HQA (basic control air amount of mass flow rate). In step 140, the actual engine speed obtained in step 100 is compared with the target engine speed, it is determined whether or not the deviation between the actual engine speed and the target engine speed is within a predetermined value, and engine speed feedback control is performed.

FIG. 9 shows a control flowchart for executing a failure diagnosis of the auxiliary air control valve 12. Step 2
At 00, it is determined whether or not conditions for performing the failure diagnosis are satisfied. Specifically, it is determined whether the engine operating state detecting means and the air amount sensor 20 are normal. In step 210, the air amount converted from the output signal of the air amount sensor 20 is calculated. This executes a search of a voltage-air amount table that converts the output voltage of the air amount sensor 20 into a mass flow rate. In step 220, the air amount corresponding to the step of the auxiliary air control valve 12 is converted into a mass flow rate. Here, the calculation of the contents described in the above equation (2) is performed on the basic control air amount QA. Step 230
Then, the detected mass flow rate of the air amount sensor calculated in steps 210 and 220 and the auxiliary air control valve 12
Then, the calculated mass flow rates converted from the number of steps are compared to determine whether or not the difference is larger than a predetermined value. Here, if the difference is smaller than a predetermined value, it is diagnosed as normal, and if it is larger than the predetermined value, it is determined that the auxiliary air control valve 12 has failed,
The processing shifts to each processing based on the predetermined diagnosis result, and the program ends.

As described above, one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above-described embodiment, and may be designed without departing from the spirit of the invention described in the appended claims. Can be variously changed.

[0051]

As can be understood from the above description, the diagnostic device for the intake air amount control device according to the present invention does not have a dedicated detecting means for diagnosing the failure of the auxiliary air control valve, and can provide the auxiliary device with high accuracy and low cost. A failure of the air control valve can be detected, and as a result, an intake air amount control device excellent in safety can be provided.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an engine system of an embodiment of an engine intake air amount control device including a diagnostic device of the present invention.

FIG. 2 is an internal configuration diagram of the intake air amount control device (controller) of FIG. 1;

FIG. 3 is a control block diagram of the intake air amount control device of FIG. 1;

FIG. 4 is a relationship diagram between a target rotation speed of the engine of FIG. 1 and an engine cooling water temperature.

FIG. 5 is a diagram showing the relationship between the amount of air of an auxiliary air control valve of the engine of FIG. 1 and the number of steps of a stepping motor.

FIG. 6 is a relationship diagram between an output voltage of an air amount sensor of the engine of FIG. 1 and an intake air amount;

FIG. 7 is a diagram showing a relationship between a step number indicating an opening area of an auxiliary air control valve of the engine of FIG. 1 and a threshold value (failure determination value) of an air amount for determining a failure of the auxiliary air control valve.

FIG. 8 is a normal control flowchart of a diagnostic device of the intake air amount control device of FIG. 1;

FIG. 9 is a control flowchart for executing a failure diagnosis of an auxiliary air control valve of the diagnostic device of the intake air amount control device of FIG. 1;

FIG. 10 is a diagram showing a relationship between opening and closing of an auxiliary air control valve and an excitation pattern of a drive excitation phase of a stepping motor (four phases) for driving the control valve.

FIG. 11 is a diagram illustrating an example of a drive monitor circuit of a stepping motor that drives an auxiliary air control valve.

FIG. 12 is a diagram illustrating a relationship between a drive signal of the stepping motor of FIG. 10 and a monitor signal;

[Explanation of symbols]

 2 Throttle body 3 Throttle valve 4 Surge tank 5 Intake branch pipe 6 Intake valve 7 Cylinder head 8 Combustion chamber 9 Exhaust valve 10 Exhaust branch pipe 11 Fuel injection valve 12 Auxiliary air control valve 13 Control unit 16 Cylinder 20 Air amount sensor 61 Operating state Detection means 62 Basic air amount calculation means 63 Intake air amount calculation means 64 Auxiliary air control valve control means 65 Target rotation speed setting means 66 Actual rotation speed detection means 67 Actual intake air amount calculation means 68 Auxiliary air control valve failure diagnosis means 69 Diagnosis area Judging means 70 Operating state judging means

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Kazuya Kono 2520 Ojitakaba, Hitachinaka City, Ibaraki Prefecture Inside the Automotive Equipment Division, Hitachi, Ltd. (72) Inventor Yuji Ikeda 2477 Takaba, Hitachinaka City, Ibaraki Stock Company Hitachi Car Engineering Co., Ltd. (72) Inventor Tomoharu Sasaki 2520 Oita Takaba, Hitachinaka-shi, Ibaraki F-term in the Automotive Equipment Division, Hitachi, Ltd. 3G084 BA03 BA04 BA06 DA27 DA31 EB22 FA01 FA02 FA07 FA10 FA13 FA20 FA31 FA33 3G301 JB02 JB09 KA07 LA04 LB01 LC04 MA12

Claims (14)

[Claims] 1. Means for detecting an operating state of an engine;
Means for calculating an intake air amount based on an output signal of the operating state detection means, and controlling an auxiliary air control valve for bypassing a throttle valve and flowing auxiliary air based on an output signal of the intake air amount calculation means. An intake air amount control device for an engine, comprising: a means for calculating an actual intake air amount of the engine; and an auxiliary air control valve failure diagnosis means,
The auxiliary air control valve failure diagnosis unit compares the actual intake air amount calculated by the actual intake air amount calculation unit with the intake air amount calculated by the intake air amount calculation unit, and based on the comparison result, compares the auxiliary air amount based on the comparison result. An intake air amount control device for an engine, comprising a diagnostic device for diagnosing a failure of a control valve. 2. The auxiliary air control valve failure diagnosing means calculates a difference between an intake air amount calculated by the intake air amount calculating means and an actual intake air amount calculated by the actual intake air amount calculating means. The intake air amount control device for an engine, comprising: the diagnostic device according to claim 1, wherein the difference amount is compared with a failure determination value for diagnosis. 3. The failure determination value is set according to the intake air amount (atmospheric pressure, intake air amount after intake air temperature correction) calculated by the intake air amount calculation means. An intake air amount control device for an engine, comprising the diagnostic device according to (1). 4. The intake air amount control device includes means for setting a target rotation speed based on an output signal of the operating state detecting means, and basic air amount calculating means, wherein the intake air amount calculating means comprises The basic intake air amount calculated by the basic air amount calculating means is corrected by making the target rotational speed coincide with the actual rotational speed.
An intake air amount control device for an engine, comprising the diagnostic device according to any one of the preceding claims. 5. The intake air amount control device includes means for determining a diagnosis area for a failure diagnosis of the auxiliary air control valve,
The diagnostic device according to any one of claims 1 to 4, wherein the diagnostic region determining unit determines whether to permit the diagnostic of the auxiliary air control valve failure diagnostic unit, interrupt the diagnosis, or discard the diagnosis result. Engine air intake control device 6. The intake air amount control device includes means for determining an operation state of the engine, and the diagnosis area determination means determines a diagnosis area based on a determination result of the operation state determination means. An intake air amount control device for an engine, comprising the diagnostic device according to claim 5. 7. The intake air amount control device includes a timer unit and / or an engine rotation angle detection unit. When diagnosis is permitted, a predetermined value is determined based on an output signal of the timer unit or the engine rotation angle detection unit. An intake air amount control device for an engine, comprising: the diagnostic device according to claim 5, wherein a delay period is set. 8. The at least one operating means for calculating an engine load based on the actual intake air amount and the actual rotational speed, or at least one of means for judging an idle state by the operating state detecting means. An intake air amount control device for an engine, comprising: the diagnostic device according to claim 6. 9. The operating state determining means includes means for determining an atmospheric pressure state by the operating state detecting means, and the diagnostic area determining means determines that an atmospheric pressure value in the atmospheric pressure state determining means is greater than a predetermined value. The control device according to claim 6, wherein when the temperature is low, the diagnosis is prohibited, interrupted, or discarded. 10. The operating state determining means includes means for determining an intake air temperature state by the operating state detecting means,
The diagnostic device according to claim 6, wherein the diagnostic region determining means prohibits, interrupts, or discards a diagnostic result when the intake air temperature in the intake air temperature state determining means is higher than a predetermined value. Engine air intake control device 11. The operating state determining means includes means for detecting an intake pipe negative pressure, or means for estimating the intake pipe negative pressure, and the diagnostic region determining means performs a diagnosis based on the intake pipe negative pressure. An intake air amount control device for an engine, comprising: the diagnostic device according to claim 6, wherein the region is determined. 12. The method according to claim 1, wherein the operating state determining means includes an engine speed, and the diagnosis area determining means prohibits, interrupts, or discards a diagnosis result when the engine speed is lower than a predetermined value. An intake air amount control device for an engine, comprising the diagnostic device according to claim 6. 13. The intake air amount control device comprises an atmospheric pressure detecting means or an atmospheric pressure estimating means and an atmospheric pressure correcting means, wherein the atmospheric pressure correcting means calculates the intake air amount calculated by the intake air amount calculating means. 4. The engine according to claim 3, wherein one of the difference amount and the failure determination value is corrected by an output signal of the atmospheric pressure detecting means or the atmospheric pressure estimating means. Air flow control device. 14. The intake air amount control device includes intake air temperature detecting means or intake air temperature estimating means and intake air temperature correcting means, and the intake air temperature correcting means calculates the intake air calculated by the intake air amount calculating means. The engine according to claim 3, wherein one of the amount, the difference amount, and the failure determination value is corrected by an output signal of the intake air temperature detection unit or the intake air temperature estimation unit. Intake air amount control device.