JP4333405B2 - Secondary air supply control device, program, recording medium - Google Patents

Description

  The present invention relates to a secondary air supply control device, a program, and a recording medium, and more specifically, to realize a secondary air supply control device that supplies air compressed by an air pump to engine exhaust gas, and the secondary air supply control device. The present invention relates to a program for causing a computer system to function and a computer-readable recording medium on which the program is recorded.

  Conventionally, exhaust gas is supplied by supplying air (secondary air) to high-temperature exhaust gas discharged from an engine (internal combustion engine) and reburning unburned carbon monoxide and hydrocarbons in the exhaust gas. A secondary air supply control device (AI: Air Injection system) designed to purify water is widely used.

This secondary air supply control device includes an exhaust negative pressure utilization method and an air pump method.
In the exhaust negative pressure utilization method, the air (fresh air) sent from the air cleaner to the intake manifold is diverted, and the negative pressure in the exhaust pipe generated by exhaust pulsation is used to exhaust the air from the air cleaner through the valve. Introduce into the tube.
In the air pump system, a dedicated air pump is provided, and air compressed by the air pump is blown into the exhaust pipe through a valve.

  In the secondary air supply control device, in order to prevent deterioration of exhaust emission due to abnormalities in the secondary air supply system (the valve in the exhaust negative pressure method, the air pump and valve in the air pump method) It is required to detect system abnormalities.

  Therefore, in a failure diagnosis device for a secondary air supply system of an engine that supplies secondary air to the exhaust system via a secondary air passage, the secondary air is supplied to the exhaust system or the supply is stopped. Detect the pressure in the secondary air passage, calculate the difference between the maximum value and the minimum value of the pressure pulsation, compare the calculated difference with the preset judgment value, and supply the secondary air when it is below this judgment value A technique for determining that the system is abnormal is disclosed (see Patent Document 1).

Further, in a failure diagnosis device for an engine secondary air supply system that supplies secondary air to the exhaust system via a secondary air passage, the secondary air is supplied to the exhaust system or the supply is stopped. Detect the pressure in the secondary air passage, calculate the difference between the maximum value and the minimum value of the pressure pulsation, compare the calculated difference with the judgment value set based on atmospheric pressure data, and below this judgment value In this case, a technique for determining that the secondary air supply system is abnormal is disclosed (see Patent Document 2).
Japanese Patent Laid-Open No. 9-125946 (pages 2-7, FIGS. 2-6) Japanese Patent Laid-Open No. 9-125945 (pages 2 to 9 and FIGS. 3 to 9)

The techniques of Patent Literature 1 and Patent Literature 2 are applied to the exhaust negative pressure utilization method, and are derived from the air cleaner using the negative pressure in the exhaust system (exhaust pipe) generated by the exhaust pulsation of the engine. In this method, air is introduced into the exhaust pipe through a valve.
In the techniques of Patent Document 1 and Patent Document 2, the pressure in the secondary air passage is detected during engine operation, and the secondary air supply system is detected based on the difference between the maximum value and the minimum value of the pressure pulsation. An abnormality is being judged.

By the way, it is conceivable to apply the technique of Patent Document 1 or Patent Document 2 to an air pump system.
However, in this case, since the pressure in the secondary air passage is detected during engine operation, the detected pressure value includes not only the pressure pulsation of the engine exhaust but also pressure fluctuation due to the engine load. appear.
Therefore, even if the abnormality determination of the secondary air supply system is performed based on the difference between the maximum value and the minimum value of the pressure value, the accuracy of the abnormality determination is reduced by the amount of pressure pulsation and pressure fluctuation, and the secondary air supply There is a problem that only a clear failure of the system (air pump and valve) can be detected, and a deterioration in performance of the secondary air supply system cannot be detected.

The present invention has been made to solve the above-described problems, and has the following objects.
(1) To provide a secondary air supply control device capable of detecting an abnormality of an air pump or a valve with high accuracy in a secondary air supply control device for supplying air compressed by an air pump to engine exhaust gas.
(2) A program for causing a computer system to function so as to realize the secondary air supply control device of (1) is provided.
(3) Provided is a computer-readable recording medium on which a program for causing a computer system to function is implemented so as to realize the secondary air supply control device of (1).

(Claim 1: corresponds to the processing of S100 to S500)
According to the first aspect of the present invention, there is provided a secondary air passage for supplying secondary air to engine exhaust gas, an air pump for compressing air, and the air pump provided upstream of the secondary air passage. A valve for opening or closing the secondary air passage, the valve being provided on the downstream side of the secondary air passage, and driving and controlling the air pump and the valve, A secondary air supply control device comprising: drive control means for executing secondary air supply control for supplying air compressed by the air pump from the secondary air passage to the exhaust gas of the engine through the valve. Air pressure detecting means for detecting the air pressure in the secondary air passage, and the air pump or the valve based on the air pressure in the secondary air passage detected by the air pressure detecting means. And abnormality detecting means for detecting an abnormality, the timing means the engine for measuring an elapsed time from the stop, when the elapsed time the counting means has measured reaches the predetermined time, the drive control means and the A start means for starting the operation of the abnormality detection means, and the drive control means is configured such that when the engine is stopped, the air pump is stopped and the valve is closed, and the air pump is The abnormality detecting means detects a change in the air pressure in the secondary air passage between the first state and the second state, and switches between the second state in which the valve is open while operating. It is a technical feature to determine whether the air pump or the valve is abnormal by referring to a change in air pressure with a preset change pattern.

(Claim 2: Corresponds to the processing of S600, S700, S800, S1100)
According to a second aspect of the present invention, in the secondary air supply control device according to the first aspect, when the engine is stopped, the drive control unit first stops the air pump and closes the valve. In the fourth state in which the air pump is operated and the valve is closed, and the abnormality detecting means is preset with the air pressure in the secondary air passage in the fourth state. The first threshold value is compared with the second threshold value set to a value larger than the first threshold value, and the air pump is used when the air pressure is less than the first threshold value. When the air pressure is not less than the first threshold value and less than the second threshold value, it is determined that the performance of the air pump has deteriorated, and the air pressure is not less than the second threshold value. normal the air pump has And technical features determining that the others are substantially normal.

(Claim 3)
According to a third aspect of the present invention, in the secondary air supply control device according to the second aspect, the first threshold value is set to a minimum air pressure necessary for normal secondary air supply control, and The second threshold is technically characterized by being set to an air pressure obtained by adding a predetermined margin to the first threshold.

(Claim 4: Corresponds to the processing of S600 to S1000, S1200 to S1400)
According to a fourth aspect of the present invention, in the secondary air supply control device according to any one of the first to third aspects of the present invention, when the engine is stopped, the drive control means first starts the air pump. The first state where the valve is closed and the valve is closed, and then the fourth state where the air pump is operated and the valve is closed, and then the air pump is stopped and the valve is opened. The abnormality detection means detects a time change of the air pressure in the secondary air passage in the fourth state and the fifth state, and performs the performance of the valve based on the time change of the air pressure in each state. It is a technical feature to determine the decrease.

(Claim 5)
According to a fifth aspect of the present invention, in the secondary air supply control device according to the fourth aspect, the abnormality detecting unit is configured to perform the operation based on a time change of the air pressure in the secondary air passage in the fourth state. Determining whether or not the valve closes normally or approximately normally, and determining whether or not the valve opens normally or approximately normally based on a temporal change in air pressure in the secondary air passage in the fifth state. Technical features.

( Claim 6 : corresponds to the processing of S1500)
A sixth aspect of the present invention is the secondary air supply control device according to any one of the first to fifth aspects, further comprising a storage unit that stores a detection result of the abnormality detection unit. And

( Claim 7 : corresponds to the processing of S1600)
A seventh aspect of the present invention is the secondary air supply control device according to any one of the first to sixth aspects, further comprising display means for displaying a detection result of the abnormality detection means. And

( Claim 8 : corresponds to the process of S1700)
The invention according to claim 8 is the secondary air supply control device according to any one of claims 1 to 7 , wherein the abnormality detecting means detects an abnormality of at least one of the air pump or the valve. The present invention is technically characterized by including prohibiting means for prohibiting execution of secondary air supply control by the driving means.

( Claim 9 )
A ninth aspect of the present invention provides a program for causing a computer system to function as each of the means in the secondary air supply control apparatus according to any one of the first to eighth aspects.

( Claim 10 )
The invention according to claim 10 is readable by a computer in which a program for causing a computer system to function as each means in the secondary air supply control device according to any one of claims 1 to 8 is recorded. A recording medium is provided.

(Claim 1)
According to the first aspect of the present invention, when the engine is stopped, the abnormality detecting means detects a change in the air pressure in the secondary air passage between the first state and the second state. When the engine is stopped, the air pressure in the secondary air passage detected by the air pressure detection means is not affected by the pressure pulsation of the exhaust gas of the engine and the pressure fluctuation due to the engine load does not occur. It becomes a constant value. Therefore, the abnormality detection means can accurately detect a change in the air pressure in the secondary air passage between the first state and the second state, and can accurately detect an abnormality in the air pump or the valve based on the change in the air pressure. It can be detected.
According to the first aspect of the present invention, when a predetermined time has elapsed since the engine was stopped, the operation of the drive control unit and the abnormality detection unit is started by the start unit. That is, since the abnormality detection operation of the air pump and the valve is automatically started, it is not necessary for the driver to perform any operation during the abnormality detection operation. The predetermined time may be set by experimentally finding the optimum value by cut-and-try. Further, the predetermined time may be freely set and changed at the time of shipment or inspection / inspection of the secondary air supply control device.

(Claim 2)
In the invention according to claim 2, when the engine is stopped, the abnormality detecting means detects the abnormality of the valve based on the air pressure in the secondary air passage in the fourth state. When the engine is stopped, the air pressure in the secondary air passage detected by the air pressure detection means is not affected by the pressure pulsation of the exhaust gas of the engine and the pressure fluctuation due to the engine load does not occur. It becomes a constant value. Therefore, the abnormality detection means can accurately detect the air pressure in the secondary air passage in the fourth state, and can detect the performance degradation of the air pump with high accuracy based on the air pressure.

(Claim 3)
According to the third aspect of the present invention, the first threshold value and the second threshold value can be set optimally. The predetermined margin may be set by experimentally finding the optimum value by cut-and-try.

(Claim 4)
In the invention according to claim 4, when the engine is stopped, the abnormality detecting means detects the time change of the air pressure in the secondary air passage in the fourth state and the fifth state. When the engine is stopped, the air pressure in the secondary air passage detected by the air pressure detecting means is not subjected to the pressure pulsation of the exhaust gas of the engine, and the pressure fluctuation due to the engine load does not occur. In addition, the pressure pulsation and the fluctuation due to the pressure fluctuation do not occur in the time change of the air pressure in the secondary air passage in the fifth state. Therefore, the abnormality detection means can accurately detect the time change of the air pressure in the secondary air passage in the fourth state and the fifth state, and based on the time change of the air pressure, the deterioration of the valve performance can be accurately performed. It can be detected.

(Claim 5)
According to the fifth aspect of the present invention, whether or not the secondary air passage can be normally opened and closed by the valve can be accurately detected for both opening and closing of the valve.

( Claim 6 )
According to the sixth aspect of the present invention, since the detection result of the abnormality detection means is stored in the storage means, if the detection result of the abnormality detection means stored in the storage means is verified, the abnormality of the air pump and the valve Therefore, it is possible to accurately maintain the secondary air supply control device.

( Claim 7 )
According to the invention described in claim 7 , since the detection result of the abnormality detection means is displayed on the display means, the abnormality of the air pump and the valve can be recognized by the display of the display means, and a repair shop is requested for inspection and repair. You can take measures such as

( Claim 8 )
According to the invention described in claim 8 , when the abnormality detecting means detects at least one abnormality of the air pump or the valve, the execution of the secondary air supply control by the driving means is prohibited by the prohibiting means. That is, if at least one of the air pump and the valve is abnormal, the secondary air supply control cannot be executed normally. Therefore, if the secondary air supply control is forcibly executed, other controls (for example, engine fuel injection control) Etc.) may be adversely affected. Therefore, in the invention described in claim 9, by prohibiting the execution of the secondary air supply control, it is possible to prevent the other control from being adversely affected and to realize fail-safe.

( Claim 9, Claim 10 )
According to invention of Claim 9 , the program for functioning a computer system can be provided so that the secondary air supply control apparatus of any one of Claims 1-8 may be implement | achieved.
Further, according to the invention described in claim 10 , it is possible to provide a computer-readable recording medium in which the program of claim 9 is recorded.

For example, the program can be recorded by using a ROM or backup RAM as a computer-readable recording medium, and the ROM or backup RAM can be incorporated into a computer system.
In addition, the program is recorded (stored) in an external recording device (external storage device) having a computer-readable recording medium, and the program is loaded from the external recording device to the computer system as necessary. May be used.

(Explanation of terms)
The correspondence between the constituent elements described in [Means for Solving the Problems] described above and the constituent members described in [Best Mode for Carrying Out the Invention] described below is as follows. .

The “drive control means” corresponds to the processes of S300, S600, S700, and S900 executed by the engine control electronic control unit (ECU) 28 and the microcomputer 50.
The “air pressure detecting means” corresponds to the processing of S200, S400, S800, and S1000 executed by the pressure sensor 24 and the microcomputer 50.
The “abnormality detection unit” corresponds to the processing of S500, S1100, and S1400 executed by the microcomputer 50.

The “first state” in claim 1 corresponds to the state in the process of S200 executed by the microcomputer 50.
The “first state” in claim 2 or claim 4 corresponds to a state in the process of S600 executed by the microcomputer 50.
The “second state” corresponds to the state in the process of S300 executed by the microcomputer 50.
The “fourth state” corresponds to a state in the process of S700 executed by the microcomputer 50.
The “fifth state” corresponds to a state in the process of S900 executed by the microcomputer 50.

The “first threshold value” corresponds to the pressure value Pta.
The “second threshold value” corresponds to the pressure value Pta.
“Time measuring means” corresponds to the ignition switch 36, the soak timer IC 60, the external oscillation element 68, and the microcomputer 50.
The “starting means” corresponds to the processing of S100 executed by the electromagnetic relay 30, the vehicle-mounted battery 32, the internal power supply IC 42, the relay control IC 44, the soak timer IC 60, and the ECU 28.

The “storage unit” corresponds to the RAM 56.
The “display means” corresponds to the warning lamp 26.
The “program” corresponds to the processing of the flowcharts shown in FIGS. 3 and 4 executed by the engine control electronic control unit (ECU) 28.
“Recording medium” corresponds to the ROM 54.

  Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings.

[Main configuration of the embodiment]
FIG. 1 is a block diagram showing a schematic configuration of a secondary air supply control device 10 of the present embodiment.
The secondary air supply control device 10 includes an automobile engine (internal combustion engine) 12, an exhaust pipe 14, a catalytic converter 16, a secondary air passage 18, an air pump (AP) 20, an air switching valve (ASV). ) 22, pressure sensor 24, warning lamp 26, engine control electronic control unit (ECU) 28, electromagnetic relay 30, in-vehicle battery 32, fuse 34, ignition switch 36, etc., which are mounted on the automobile.
The warning lamp 26 is attached to an instrument panel (not shown).

In the engine 12, the fuel injection device 12a injects an optimal amount of fuel into the sucked air to generate a mixture of air and fuel. After the mixture is compressed in the cylinder, a spark plug (not shown) Use to ignite and explode. Exhaust gas generated with the explosion is discharged from the exhaust pipe 14 through the catalytic converter 16 to the outside.
A three-way catalyst is accommodated in the catalytic converter 16.

A secondary air passage 18 is connected to the exhaust pipe 14 upstream of the catalytic converter 16 (between the exhaust manifold of the engine 12 and the catalytic converter 16). An air pump 20 is provided upstream of the secondary air passage 18, and a valve 22 is provided downstream of the secondary air passage 18.
The valve 22 opens or closes the secondary air passage 18 according to the drive control of the ECU 28.
A pressure sensor 24 for detecting the air pressure in the secondary air passage 18 is provided between the air pump 20 and the valve 22 in the secondary air passage 18.
Then, the air compressed by the air pump 20 is blown into the exhaust pipe 14 from the secondary air passage 18 through the valve 22.

  As a result, in the exhaust pipe 14, air (secondary air) compressed by the air pump 20 is supplied to the high-temperature exhaust gas exhausted from the engine 12, and unburned carbon monoxide and carbonization in the exhaust gas are supplied. Hydrogen is reburned. At this time, by optimizing the amount of air supplied from the air pump 20 through the valve 22, the inflow air-fuel ratio flowing into the three-way catalyst in the catalytic converter 16 is made constant, and the exhaust gas purification rate by the three-way catalyst is made constant. Can be improved.

The ECU 28 controls the valve 22 from the air pump 20 as described above by driving and controlling the secondary air supply system (the air pump 20 and the valve 22) based on the air pressure in the secondary air passage 18 detected by the pressure sensor 24. The secondary air supply control for purifying the exhaust gas by optimizing the amount of air supplied via the air is executed.
The ECU 28 controls the rotation of the engine 12 by optimally controlling the fuel injection of the fuel injection device 12a.
Then, the ECU 28 performs an abnormality detection operation for detecting an abnormality of the secondary air supply system (the air pump 20 and the valve 22) based on the air pressure in the secondary air passage 18 detected by the pressure sensor 24.

[Internal configuration of ECU]
FIG. 2 is a block diagram showing a schematic configuration inside the ECU 28 of the present embodiment.
The ECU 28 includes an internal power supply IC (Integrated Circuit) 42, a relay control IC 44, a microcomputer (hereinafter abbreviated as “microcomputer”) 50, a soak timer IC 60, and the like, and is provided with external connection terminals + B, MREL, and IGSW. It has been. The minus terminal of the on-vehicle battery 32 and the ECU 28 are commonly grounded.

The electromagnetic relay 30 includes contact points 30a and 30b, an armature 30c, and an electromagnet coil 30d. In the electromagnetic relay 30, when the electromagnet coil 30d is energized, the armature 30c connects the contacts 30a and 30b.
The external connection terminal + B is connected to the contact 30 a of the electromagnetic relay 30. The contact 30 b of the electromagnetic relay 30 is connected to the plus terminal of the in-vehicle battery 32 and the contact 36 a of the ignition switch 36 via the fuse 34.

The external connection terminal MREL is grounded through the electromagnetic coil 30 d of the electromagnetic relay 30.
The external connection terminal IGSW is connected to the contact 36 b of the ignition switch 36.

When the contacts 30a and 30b of the electromagnetic relay 30 are connected, the DC voltage of the in-vehicle battery 32 is applied to the internal power supply IC 42 via the external connection terminal + B.
Then, the internal power supply IC 42 steps down the DC voltage (+12 V) of the in-vehicle battery 32 to generate the internal power supply voltage Vcc (+5 V), and supplies the internal power supply voltage Vcc to the microcomputer 50.

  The relay control IC 44 and the soak timer IC 60 are supplied with a power supply voltage Vos from a dedicated power source (not shown) such as a battery, not from the in-vehicle battery 32. Therefore, regardless of the operation of the electromagnetic relay 30, the ICs 44 and 60 are always operable.

The microcomputer 50 includes a central processing unit (CPU) 52, a read-only storage device (ROM) 54, a readable / writable storage device (RAM) 56, an input / output device (I / O) 58, and the like.
The I / O 58 is connected to the fuel injection device 12a, the air pump 20, the valve 22, the pressure sensor 24, the warning lamp 26, and the ignition switch 36. The control signal generated by the microcomputer 50 is output from the I / O 58 to the controlled device (fuel injection device 12a, air pump 20, valve 22, warning lamp 26), and detection signals from the pressure sensor 24 and the ignition switch 36 are output. Input from the I / O 58 to the microcomputer 50.

The soak timer IC 60 includes a timer unit 62, a communication interface (I / F) 64, and an OR circuit 66. An external oscillation element (crystal oscillator or ceramic oscillator) 68 is externally attached to the timer unit 62.
The timer unit 62 measures time based on the clock signal generated by the external oscillation element 68, and generates and outputs a drive signal DSa when the measured time reaches a predetermined time.
The communication I / F 64 is connected to the I / O 58 of the microcomputer 50 and transmits / receives a control signal CS to / from the microcomputer 50.

The OR circuit 66 is connected to the I / O 58 of the microcomputer 50 and the timer unit 62, takes an OR logic of the drive signal DSb from the microcomputer 50 and the drive signal DSa from the timer unit 62, and generates an output signal. The signal is output to the relay control IC 44.
The relay control IC 44 incorporates an OR circuit. The OR circuit in the relay control IC 44 generates an output signal by taking the OR logic of the signal applied to the external connection terminal IGSW and the output signal of the OR circuit 66, and outputs the output signal to the external connection terminal MREL.

When the driver turns on the ignition switch 36, the contacts 36a and 36b of the ignition switch 36 are connected, and the DC voltage of the in-vehicle battery 32 is applied to the relay control IC 44 via the external connection terminal IGSW of the ECU 28.
Then, the in-vehicle battery 32 → contact 36a → contact 36b → external connection terminal IGSW → OR circuit in the relay control IC 44 → external connection terminal MREL of the ECU 28 → electromagnetic coil 30d of the electromagnetic relay 30 → current flows through the ground path, and the electromagnet The coil 30d is energized.

  Therefore, the armature 30c of the electromagnetic relay 30 connects the contacts 30a and 30b (that is, the electromagnetic relay 30 is turned on), and the DC voltage of the in-vehicle battery 32 is connected to the internal power supply IC 42 via the external connection terminal + B of the ECU 28. To be applied.

As a result, the internal power supply voltage Vcc generated by the internal power supply IC 42 is supplied to the microcomputer 50, the power is turned on to the microcomputer 50, and the microcomputer 50 is activated.
Then, the microcomputer 12 starts the engine 12, the fuel injection of the fuel injection device 12a is controlled, and the rotation of the engine 12 is controlled. Further, the microcomputer 50 drives and controls the secondary air supply system (the air pump 20 and the valve 22) to execute the secondary air supply control.

When the driver turns off the ignition switch 36, the contacts 36a and 36b of the ignition switch 36 are disconnected, and the current flowing from the vehicle-mounted battery 32 to the electromagnetic coil 30d of the electromagnetic relay 30 is cut off, and the electromagnetic coil 30d. Is de-energized.
Therefore, the armature 30c of the electromagnetic relay 30 releases the connection between the contacts 30a and 30b (that is, the electromagnetic relay 30 is turned off), and the power supply from the on-vehicle battery 32 to the internal power supply IC 42 is stopped. .

As a result, the generation of the internal power supply voltage Vcc by the internal power supply IC 42 is stopped, the supply of the internal power supply voltage Vcc to the microcomputer 50 is also stopped, and the operation of the microcomputer 50 is stopped.
Then, the drive control of the engine 12 by the microcomputer 50 is stopped, and the rotation of the engine 12 is stopped. Further, the drive control of the secondary air supply system (the air pump 20 and the valve 22) by the microcomputer 50 is also stopped, the air pump 20 is stopped (off), and the valve 22 is closed.

[Abnormality detection operation]
3 and 4 are flowcharts showing the flow of the abnormality detection operation of the secondary air supply system (the air pump 20 and the valve 22) executed by the ECU 28 in the present embodiment.

In the present embodiment, the abnormality detection operation of the secondary air supply system is performed in a state where the ignition switch 36 is turned off and the operation of the engine 12 is stopped.
First, in the processing of step 100, when a predetermined time T (for example, several hours) elapses after the driver turns off the ignition switch 36 to stop the operation of the engine 12, the microcomputer 50 is activated by the soak timer IC 60. .

  That is, when the driver turns off the ignition switch 36 to stop the operation of the engine 12, a signal indicating that the ignition switch 36 is turned off is output from the ignition switch 36 to the microcomputer 50.

  Then, before the supply of the internal power supply voltage Vcc is stopped and the operation of the microcomputer 50 is stopped as described above, the microcomputer 50 operates the timer unit 62 of the soak timer IC based on the signal from the ignition switch 36. Is generated from the I / O 58 to the timer unit 62 via the communication I / F 64 of the soak timer IC.

When the control signal CS is input, the timer unit 62 starts measuring time, and generates and outputs the drive signal DSa when the measured time reaches a predetermined time T.
The drive signal DSa is output via the OR circuit 66 of the soak timer IC → the OR circuit in the relay control IC 44 → the external connection terminal MREL of the ECU 28 → the electromagnet coil 30d of the electromagnetic relay 30 → the grounding path to energize the electromagnet coil 30d. .

Then, the armature 30c of the electromagnetic relay 30 connects the respective contacts 30a and 30b (that is, the electromagnetic relay 30 is turned on), and the DC voltage of the in-vehicle battery 32 is connected to the internal power supply IC 42 via the external connection terminal + B of the ECU 28. To be applied.
As a result, the internal power supply voltage Vcc generated by the internal power supply IC 42 is supplied to the microcomputer 50, the power is turned on to the microcomputer 50, and the microcomputer 50 is activated.

When the microcomputer 50 is activated, the CPU 52 loads a computer program stored (recorded) in the ROM 54 and executes various arithmetic processes in accordance with the computer program, so that the engine 12 is stopped without being started. Step processing is executed.
In the drawings and the following description, a step is described as “S”.

  By the way, the computer program is recorded not in the ROM 54 built in the microcomputer 50 but in a backup RAM (not shown) built in the microcomputer 50 or an external recording device (external storage device) (not shown) provided with a computer-readable recording medium ( The computer program may be loaded into the CPU 52 from a backup RAM or an external recording device and used as needed.

  Incidentally, computer-readable recording media include semiconductor memory (smart media, memory stick, etc.), hard disk, FD (Floppy Disk), data card (IC card (IC: Integrated Circuit), magnetic card, etc.), optical disk ( CD-ROM, DVD, etc.), magneto-optical disk (MO, etc.), phase change disk, magnetic tape, etc. The names of specific examples of the recording medium include registered trademarks.

First, the microcomputer 50 captures the detection signal of the pressure sensor 24 via the I / O 58 in a state where the air pump 20 is stopped (off) and the valve 22 is closed (first state). The detected air pressure is stored in the RAM 56 (S200).
Next, the microcomputer 50 forcibly drives the secondary air supply system to operate (turn on) the air pump 20 and open the valve 22 (second state: S300), and the detection signal of the pressure sensor 24 at that time Is taken in via the I / O 58, the air pressure in the secondary air passage 18 is detected, and the detection result is stored in the RAM 56 (S400).

FIG. 5 is a graph showing the time change of the air pressure in the secondary air passage 18 accompanying the operation / stop (on / off) of the air pump 20 and the opening / closing of the valve 22 in the present embodiment.
The microcomputer 50 reads out the air pressure in the secondary air passage 18 detected in each process of S200 and S400 from the RAM 56, and refers to the change pattern of the detected air pressure with the time change of the air pressure shown in FIG. As shown in FIG. 5, a failure of the secondary air supply system (air pump 20 and valve 22) is determined (S500).

That is, as shown in FIG. 5, when the air pump 20 operates (turns on) and the valve 22 is open (pattern A), the air pressure in the secondary air passage 18 becomes a positive pressure value P1.
When the air pump 20 is stopped (off) (pattern B), the air pressure in the secondary air passage 18 becomes zero regardless of whether the valve 22 is opened or closed.

Further, when the air pump 20 is operated (ON) and the valve 22 is closed (pattern C), the air pressure in the secondary air passage 18 becomes a positive pressure value P2.
The pressure value P2 of the pattern C is larger than the pressure value P1 of the pattern A (P2>P1> 0) because the valve 22 is closed in the pattern C and the air compressed by the air pump 20 is In the pattern A, since the valve 22 is open, the air compressed by the air pump 20 passes through the valve 22 to the exhaust pipe 14. is there.

  Therefore, as shown in FIG. 6, when both the secondary air supply systems (air pump 20 and valve 22) are normal, the process of S200 (the state where the valve 22 is closed while the air pump 20 is stopped (off)). In pattern B and S400 (the state in which the air pump 20 operates (turns on and the valve 22 is open)), pattern A is obtained, and the change in air pressure in the secondary air passage 18 changes from pattern B to A.

Even when the air pump 20 is normal and a failure (open fixation) occurs in which the valve 22 remains open regardless of the drive control of the microcomputer 50, the change in air pressure in the secondary air passage 18 is caused by the pattern B → Become A.
In addition, when the air pump 20 is normal and a failure that causes the valve 22 to remain closed regardless of the drive control of the microcomputer 50 (closed fixing) occurs, the pattern B in the process of S200 and the pattern C in the process of S400. Thus, the change in air pressure in the secondary air passage 18 changes from pattern B to C.

In addition, when the malfunction (ON abnormality) that causes the air pump 20 to remain in operation regardless of the drive control of the microcomputer 50 and the valve 22 is normal, the pattern C in the process of S200 and the pattern A in the process of S400 are obtained. The air pressure change in the secondary air passage 18 changes from the pattern C to A.
Further, when the air pump 20 is abnormally turned on and the valve 22 is stuck open, both processes in S200 and S400 result in pattern A, and the change in air pressure in the secondary air passage 18 changes from pattern A to A. become.
Further, when the air pump 20 is abnormally turned on and the valve 22 is closed and stuck, the processing in S200 and S400 both results in pattern C, and the change in air pressure in the secondary air passage 18 changes from pattern C → C. become.

  In addition, when a failure (off abnormality) in which the air pump 20 remains stopped regardless of the drive control of the microcomputer 50 is caused, both patterns in S200 and S400 are performed regardless of whether the valve 22 is normal or abnormal. B, and the air pressure change in the secondary air passage 18 changes from the pattern B to B.

  Therefore, in the process of S500, the microcomputer 50 determines that the air pump 20 is normal when the air pump 20 is normal and the valve 22 is normal or openly fixed (pattern B → A) based on the change pattern of the air pressure in the secondary air passage 18. When the valve 22 is normally closed and closed (pattern B → C), when the air pump 20 is abnormally on and the valve 22 is normal (pattern C → A), when the air pump 20 is abnormally on and the valve 22 is fixed open (pattern) A → A), the case where the air pump 20 is abnormally on and the valve 22 is closed and closed (pattern C → C), and the case where the air pump 20 is abnormally off (pattern B → B) are determined separately.

Next, the microcomputer 50 stops (turns off) the air pump 20 and closes the valve 22 ( first state : S600).
Then, the microcomputer 50 performs forced driving of only the air pump 20, operates (turns on) the air pump 20 with the valve 22 closed (fourth state: S700), and outputs a detection signal of the pressure sensor 24 at that time. The air pressure is taken in through the I / O 58, the air pressure in the secondary air passage 18 is detected, and the detection result is stored in the RAM 56 (S800).

  Subsequently, the microcomputer 50 stops (turns off) the air pump 20 and opens the valve 22 (fifth state: S900), takes in the detection signal of the pressure sensor 24 at that time via the I / O 58, and extracts the secondary air. The air pressure in the passage 18 is detected, and the detection result is stored in the RAM 56 (S1000).

The microcomputer 50 reads the air pressure in the secondary air passage 18 detected in the process of S800 from the RAM 56, and refers to the detected air pressure with the time change of the air pressure shown in FIG. The presence or absence is determined (S1100).
That is, as shown in FIG. 5, when the air pump 20 operates (turns on) and the valve 22 is closed (pattern C), the air pressure in the secondary air passage 18 should be a positive pressure value P2. .

However, when the performance of the air pump 20 decreases, the pressure of the air compressed by the air pump 20 decreases according to the degree of the performance decrease.
Therefore, by performing an experiment to check whether the secondary air supply control is normally performed when the air pressure in the secondary air passage 18 is changed, the minimum pressure value necessary for the normal secondary air supply control is determined. A (first threshold value) Pta and a pressure value (second threshold value) Ptb obtained by adding a sufficient margin to the pressure value Pta are obtained. The margin may be set by experimentally finding the optimum value by cut-and-try.

  A region γ where the air pressure in the secondary air passage 18 is zero or more and less than the pressure value Pta, a region β where the air pressure is the pressure value Pta or more and less than the pressure value Ptb, and the air pressure is the pressure value Ptb or more and the pressure value P2 or less. Are set, and the set areas α to γ are stored in the ROM 54.

  In the process of S1100, the microcomputer 50 refers to the areas α to γ stored in the ROM 54, and if the air pressure in the secondary air passage 18 detected in the process of S800 is within the area γ, the air pump 20 When it is determined that the air pump is in the region β, it is determined that the performance of the air pump 20 has deteriorated. When the air pressure is in the region α, the air pump 20 is normal or substantially normal. It is determined that

Next, the microcomputer 50 reads out the air pressure in the secondary air passage 18 detected in the process of S800 from the RAM 56, calculates the time change of the air pressure, calculates the rising slope of the time change of the air pressure, The rising slope of the time change is stored in the RAM 56 (S1200).
Subsequently, the microcomputer 50 reads the air pressure in the secondary air passage 18 detected in the process of S1000 from the RAM 56, calculates the time change of the air pressure, calculates the falling gradient of the time change of the air pressure, and the air pressure Is stored in the RAM 56 (S1300).

  The microcomputer 50 detects the air pressure at each sampling time by fetching the detection signal of the pressure sensor 24 via the I / O 58 at every fixed sampling time (for example, 4 msec) in each process of S800 and S1000. Therefore, the time change of the air pressure can be calculated with the sampling time as one unit.

  Then, the microcomputer 50 reads from the RAM 56 the rising gradient and the falling gradient of the time change of the air pressure obtained in the processes of S1200 and S1300, and determines whether or not the performance of the valve 22 has deteriorated based on each gradient (S1400). ).

FIG. 7A is a graph showing the time change of the air pressure in the secondary air passage 18 during each process of S600 to S1000 when both of the secondary air supply systems (air pump 20 and valve 22) are normal. .
FIG. 7B is a graph showing the time change of the air pressure in the secondary air passage 18 during each process of S600 to S1000 in the case where the air pump 20 is normal and the performance of the valve 22 is degraded.

  When the valve 22 is normal and completely closed, the air compressed by the air pump 20 does not leak from the valve 22 when the air pump 20 is operated (ON) while the valve 22 is closed in the process of S700. As shown in FIG. 7A, the rising slope of the time change of the air pressure in the secondary air passage 18 becomes steep.

  On the other hand, when the performance of the valve 22 deteriorates and the valve 22 is not completely closed, the air compressed by the air pump 20 is operated when the air pump 20 is operated (ON) while the valve 22 is closed in the process of S700. As shown in FIG. 7B, the rising slope of the time variation of the air pressure in the secondary air passage 18 becomes gradual.

  Further, when the valve 22 is normal and completely opened, when the valve 22 is opened and the air pump 20 is stopped (turned off) in S900, the air compressed by the air pump 20 passes through the valve 22 and quickly. Since the gas is discharged into the exhaust pipe 14, as shown in FIG. 7A, the falling gradient of the time change of the air pressure in the secondary air passage 18 becomes steep.

  On the other hand, when the valve 22 deteriorates in performance and does not open completely, when the valve 22 is opened and the air pump 20 is stopped (turned off) in the process of S900, the air compressed by the air pump 20 is not compressed. Since it is difficult to pass through the valve 22, as shown in FIG. 7B, the falling gradient of the time change of the air pressure in the secondary air passage 18 becomes gentle.

  Therefore, when the valve 22 is normal and completely closed, an experiment was conducted to check the rising slope of the time change of the air pressure in the secondary air passage 18, and a sufficient margin was added to the rising slope of the time change of the air pressure. The first standard value is stored in the ROM 54.

  In addition, when the valve 22 is normal and fully opened, an experiment is conducted to examine the falling slope of the time change of the air pressure in the secondary air passage 18 and a sufficient margin is added to the falling slope of the time change of the air pressure. The set second standard value is stored in the ROM 54.

  In the process of S1400, the microcomputer 50 refers to the first standard value stored in the ROM 54, and the rising slope of the time change of the air pressure in the secondary air passage 18 calculated in the process of S1200 is within the first standard value. In some cases, it is determined that the valve 22 closes normally or substantially normally.

  In the process of S1400, the microcomputer 50 refers to the second standard value stored in the ROM 54, and the falling slope of the time change of the air pressure in the secondary air passage 18 calculated in the process of S1300 is the second standard. When it is within the value, it is determined that the valve 22 is normally or substantially normally opened.

  Next, the microcomputer 50 converts the determination result of each process of S500, S1100, and S1400 into a diagnosis code, and stores the determination result and the diagnosis code of each process in the RAM 56 (S1500).

  Subsequently, when the microcomputer 50 determines that at least one of the air pump 20 and the valve 22 is not normal or substantially normal based on the determination result of each process of S500, S1100, and S1400, the microcomputer 50 passes through the I / O 58. A control signal is output to the warning lamp 26, and the warning lamp 26 is turned on (S1600).

  If the microcomputer 50 determines that at least one of the air pump 20 and the valve 22 is not normal or substantially normal, the microcomputer 50 prohibits execution of the secondary air supply control (S1700).

Thereafter, the operation of the microcomputer 50 is stopped (S1800).
That is, the microcomputer 50 generates a control signal CS for causing the timer unit 62 of the soak timer IC to stop generating the drive signal DSa, and transmits the control signal CS to the timer unit 62 via the communication I / F 64 of the soak timer IC. To do.

Then, the timer unit 62 stops generating the drive signal DSa, and the electromagnet coil 30d is deenergized. Therefore, the armature 30c of the electromagnetic relay 30 releases the connection between the contacts 30a and 30b (that is, the electromagnetic relay 30 is turned off), and the power supply from the on-vehicle battery 32 to the internal power supply IC 42 is stopped. .
As a result, the generation of the internal power supply voltage Vcc by the internal power supply IC 42 is stopped, the supply of the internal power supply voltage Vcc to the microcomputer 50 is also stopped, and the operation of the microcomputer 50 is stopped.

[Operations and effects of the embodiment]
According to the embodiment described above in detail, the following actions and effects can be obtained.

[1] In the process of S100, the microcomputer 50 is automatically activated by the soak timer IC 60 when a predetermined time T elapses after the ignition switch 36 is turned off and the operation of the engine 12 is stopped.
When the processes of S200 to S1700 in the abnormality detection operation are completed, the microcomputer 50 stops its own operation in the process of S1800.

That is, since the abnormality detection operation is automatically started and ended, there is no need for the driver to perform any operation during the abnormality detection operation.
The predetermined time T may be set by experimentally finding an optimum value by cut-and-try. In addition, the predetermined time T may be freely set and changed when the automobile is shipped or inspected and inspected.

[2] In the process of S1500, the determination result of each process of S500, S1100, and S1400 is converted into a diag code, and the determination result and the diag code of each process are stored in the RAM 56.
Therefore, if the determination result stored in the RAM 56 is verified, the current state of the secondary air supply system (the air pump 20 and the valve 22) can be accurately grasped, and the maintenance of the secondary air supply control device 10 can be accurately determined. Can be aimed at.
Further, if the history of the diagnosis code stored in the RAM 56 is verified, the transition of the past state of the secondary air supply system can be accurately grasped, and the maintainability of the secondary air supply control device 10 can be improved. it can.

[3] In the processing of S1600, when it is determined that at least one of the air pump 20 and the valve 22 is not normal or substantially normal, the warning lamp 26 is turned on.
For this reason, the driver of the car can recognize that at least one of the air pump 20 and the valve 22 is normal or not normal by observing the lighting of the warning lamp 26, and requests an inspection and repair from a repair shop. Measures can be taken.

[4] In the processing of S1700, when it is determined that at least one of the air pump 20 and the valve 22 is not normal or substantially normal, execution of the secondary air supply control is prohibited.
That is, when at least one of the air pump 20 and the valve 22 is not normal or substantially normal, the secondary air supply control cannot be normally executed. Therefore, when the secondary air supply control is forcibly executed, another control (for example, The fuel injection control of the fuel injection device 12a) may be adversely affected.
Therefore, by prohibiting the execution of the secondary air supply control in the process of S1700, it is possible to prevent the other control from being adversely affected and to realize fail-safe.

[5] In the present embodiment, the abnormality detection operation (S200 to S1800) of the secondary air supply system (the air pump 20 and the valve 22) is performed in a state where the ignition switch 36 is turned off and the operation of the engine 12 is stopped. Done.
Therefore, as shown in FIGS. 5 and 7, the air pressure in the secondary air passage 18 detected by the pressure sensor 24 does not have the pressure pulsation of the exhaust gas in the exhaust pipe 14, and the pressure due to the load of the engine 12 Since fluctuation does not occur, the air pressure becomes a constant value.
Therefore, according to the present embodiment, in each process of S500, S1100, and S1400, an abnormality in the secondary air supply system can be detected with high accuracy, and not only an obvious failure of the secondary air supply system but also a performance degradation. Can also be detected.

FIG. 8 is a block diagram showing a schematic configuration inside the ECU 28 of the prior art.
In FIG. 8, the same constituent members as those in the embodiment shown in FIG. 8 differs from the above-described embodiment shown in FIG. 2 in that the soak timer IC 60 is omitted and the drive signal DSb generated by the microcomputer 50 is directly output to the relay control IC 44, and the ignition switch. This is that 36 detection signals are not output to the microcomputer 50.

FIG. 9 is a flowchart showing a flow of an abnormality detection operation of the secondary air supply system (the air pump 20 and the valve 22) executed by the ECU 28 in the prior art. In FIG. 9, the processing after the failure determination of the secondary air supply system is omitted.
In the prior art, the abnormality detection operation of the secondary air supply system is performed in a state where the ignition switch 36 is turned on and the secondary air supply control is being executed while the engine 12 is operating.

The microcomputer 50 operates (turns on) the air pump 20 and opens the valve 22 (S2100). The detection signal of the pressure sensor 24 at that time is taken in via the I / O 58, and the air pressure in the secondary air passage 18 is detected. Then, the detection result is stored in the RAM 56 (S2200).
Next, the microcomputer 50 stops (turns off) the air pump 20 and closes the valve 22 (S2300), takes in the detection signal of the pressure sensor 24 at that time via the I / O 58, The air pressure is detected, and the detection result is stored in the RAM 56 (S2400).

FIG. 10 is a graph showing the change over time of the air pressure in the secondary air passage 18 associated with the operation / stop (on / off) of the air pump 20 and the opening / closing of the valve 22 in the prior art.
The microcomputer 50 reads out the air pressure in the secondary air passage 18 detected in each process of S2200 and S2400 from the RAM 56, and refers to the detected change pattern of the air pressure with the time change of the air pressure shown in FIG. As shown in (2), the failure of the secondary air supply system (air pump 20 and valve 22) is determined (S2500).

  That is, as shown in FIG. 10, in the state where the air pump 20 operates (turns on) and the valve 22 is open (pattern “a”), the air pressure in the secondary air passage 18 includes the exhaust in the exhaust pipe 14. In addition to the pressure pulsation of the gas, pressure fluctuation due to the load of the engine 12 occurs. Therefore, the air pressure in the secondary air passage 18 fluctuates positively or negatively by the amount of pressure pulsation and pressure fluctuation with the positive pressure value P1 as the central value.

Further, when the air pump 20 is stopped (off) and the valve 22 is open (pattern “A”), the air pressure in the secondary air passage 18 has pressure pulsation and pressure with the negative pressure value P3 as the center value. It fluctuates positively or negatively by the amount of change.
The reason why the pressure value P3 takes a negative value is that a negative pressure is generated in the secondary air passage 18 communicated with the exhaust pipe 14 by the opened valve 22 when the exhaust gas flows into the exhaust pipe 14. Because.

Further, when the air pump 20 operates (turns on) and the valve 22 is closed (pattern “c”), the air pressure in the secondary air passage 18 is the same as in the pattern C shown in FIG. 5 of the above embodiment. Pressure value P2.
When the air pump 20 is stopped (off) and the valve 22 is closed (pattern “D”), the air pressure in the secondary air passage 18 becomes zero.

  Therefore, as shown in FIG. 11, when both of the secondary air supply systems (air pump 20 and valve 22) are normal, the process of S2200 (the state in which the air pump 20 operates (turns on and the valve 22 is open)). In pattern "A", the process of S2400 (air pump 20 is stopped (off) and valve 22 is closed) changes to pattern "D", and the air pressure change in the secondary air passage 18 changes to pattern "A" → Become "E".

Further, when the air pump 20 is normal and the valve 22 is stuck open, the pattern “A” is obtained in the process of S2200, and the pattern “I” is obtained in the process of S2400, and the air pressure change in the secondary air passage 18 is changed. Becomes the pattern “A” → “I”.
Further, when the air pump 20 is normal and the valve 22 is closed and stuck, the pattern “C” is obtained in the process of S2200 and the pattern “D” is obtained in the process of S2400, and the air pressure change in the secondary air passage 18 is changed. Becomes the pattern “U” → “D”.

Further, when the air pump 20 is abnormally turned on and the valve 22 is normal, the pattern “A” is obtained in the process of S2200, and the pattern “C” is obtained in the process of S2400, and the air pressure change in the secondary air passage 18 is the pattern. “A” → “C”.
Further, when the air pump 20 is turned on abnormally and the valve 22 is stuck open, the pattern “A” is obtained in both processes of S2200 and S2400, and the change in the air pressure in the secondary air passage 18 is the pattern “A”. A ”→“ A ”.
Further, when the air pump 20 is turned on abnormally and the valve 22 is closed and stuck, the pattern “C” is obtained in both processes of S2200 and S2400, and the change in the air pressure in the secondary air passage 18 is the pattern “ "U" → "U".

Further, when the air pump 20 is abnormally off and the valve 22 is normal, the pattern “I” is obtained by the process of S2200 and the pattern “D” is obtained by the process of S2400, and the air pressure change in the secondary air passage 18 is the pattern. “I” → “E”.
Further, when the air pump 20 is turned on abnormally and the valve 22 is stuck open, the pattern “I” is obtained in both processes of S2200 and S2400, and the change in air pressure in the secondary air passage 18 is the pattern “ “I” → “I”.
When the air pump 20 is abnormally turned on and the valve 22 is closed and stuck, the pattern “d” is obtained in both processes of S2200 and S2400, and the air pressure change in the secondary air passage 18 is the pattern “ D "→" D ".

  Therefore, in the process of S2500, the microcomputer 50 determines that the air pump 20 is normal and the valve 22 is normal (pattern “A” → “D”) based on the change pattern of the air pressure in the secondary air passage 18. Is normal and the valve 22 is fixed open (pattern “A” → “I”), and when the air pump 20 is normal and the valve 22 is closed closed (pattern “U” → “D”), the air pump 20 is abnormally on. When the valve 22 is normal (pattern “A” → “U”), when the air pump 20 is abnormally on and the valve 22 is stuck open (pattern “A” → “A”), when the air pump 20 is abnormally on and the valve 22 is In the case of closed adhering (pattern “U” → “U”), when the air pump 20 is abnormally off and the valve 22 is normal (pattern “I” → “D”), the air pump 20 is abnormally off and the valve 22 For open sticking (pattern "I" → "i"), the air pump 20 is distinguished when the valve 22 off abnormality is stuck closed (pattern "d" → "d") respectively determined.

As described above, in the conventional technique, as shown in FIG. 10, regarding the time variation patterns “a” and “b” of the air pressure in the secondary air passage 18, the air pressure in the secondary air passage 18 includes the pressure of the engine exhaust. In addition to pulsation, pressure fluctuations due to engine load occur.
Therefore, when there is no great difference between the pressure values P1 to P3, it is difficult to accurately distinguish the patterns “a” to “d”. In the process of S2500, the microcomputer 50 determines the air pressure in the secondary air passage 18. There is a risk of erroneously determining the change pattern.

Therefore, in the prior art, the accuracy of the abnormality determination in the processing of S2500 is reduced by the amount of pressure pulsation and pressure fluctuation, and only an obvious failure of the secondary air supply system (air pump 20 and valve 22) can be detected.
On the other hand, in the above embodiment, as shown in FIG. 5, since the air pressure in the secondary air passage 18 is constant and does not fluctuate, abnormality in the secondary air supply system can be detected with high accuracy in the processing of S500.

Further, in the prior art, since there is pressure pulsation and pressure fluctuation, even if the processing corresponding to the processing of S1100 of the above embodiment is performed, it is not possible to accurately determine the performance degradation of the air pump 20.
In the prior art, since there are pressure pulsations and pressure fluctuations, even if the processing corresponding to the processing of S1200 and S1300 in the above embodiment is performed, the rising slope and falling slope of the time change of the air pressure are accurately detected. As a result, even if the processing corresponding to the processing of S1400 in the above embodiment is performed, it is impossible to accurately determine the performance degradation of the valve 22.

On the other hand, in the above embodiment, as shown in FIG. 5, since the air pressure in the secondary air passage 18 is constant and does not fluctuate, the air pressure can be accurately detected, and the performance of the air pump 20 deteriorates in the process of S1100. Can be determined accurately.
In the above embodiment, as shown in FIG. 7, since the air pressure in the secondary air passage 18 does not vary due to pressure pulsation and pressure fluctuation, the rising slope and the falling of the time change of the air pressure. The gradient can be accurately detected, and the performance degradation of the valve 22 can be accurately determined in the process of S1400.

[Another embodiment]
By the way, the present invention is not limited to the above-described embodiment, and may be embodied as follows, and even in that case, operations and effects equivalent to or higher than those of the above-described embodiment can be obtained.

  (1) In the flowcharts shown in FIGS. 3 and 4, the process of S1100 may be performed after the process of S800. Further, the process of S1200 may be performed after the process of S800, and the process of S1300 may be performed after the process of S1000. And after performing the process of S100-S800, you may perform each process in order of S1100-> S600-> S700-> S800-> S1200-> S900-> S1000-> S1300-> S1400.

(2) In the above embodiment, the rising gradient of the time variation of the air pressure is calculated in the processing of S1200, the falling gradient of the time variation of the air pressure is calculated in the processing of S1300, and the valve 22 is based on each gradient in the processing of S1400. The presence or absence of performance degradation is determined.
However, when the air pressure in the secondary air passage 18 does not change with time linearly as shown in FIG. 7 but changes with a curve (eg, exponential function), the degree of time change of the air pressure in the process of S1200. Is calculated, the degree of time change of the air pressure is calculated in the process of S1300, and the presence or absence of the performance degradation of the valve 22 is determined based on each degree in the process of S1400.

(3) Although the warning lamp 26 is lit in the processing of S1600 of the above embodiment, the abnormality display of the secondary air supply system (air pump 20 and valve 22) is at least one of the visual display method and the auditory display method. Can be used.
As a visual display method, for example, in addition to the warning lamp 26, there is a method of providing a display on the instrument panel and displaying a message text on the display. As an auditory display method, for example, there is a method of sounding a warning buzzer.

  Further, when displaying a message text on the display, it may be displayed not only when the secondary air supply system is abnormal but also when it is normal. About the determination results of each process of S500, S1100, and S1400 You may make it display concretely.

The block diagram which shows schematic structure of the secondary air supply control apparatus 10 of one Embodiment which actualized this invention. FIG. 2 is a block diagram showing a schematic configuration inside an engine control electronic control unit (ECU) 28 of the secondary air supply control device 10. The flowchart which shows the flow of abnormality detection operation | movement of the air pump 20 and the valve | bulb 22 which ECU28 of one Embodiment performs. 7 is a flowchart showing a flow of an abnormality detection operation of the air pump 20 and the valve 22 executed by the ECU 28 in the embodiment. The graph which shows the time change of the air pressure in the secondary air path 18 in connection with operation | movement stop (ON / OFF) of the air pump 20, and opening and closing of the valve | bulb 22 in one Embodiment. The chart for demonstrating the failure determination of the air pump 20 and the valve | bulb 22 in one Embodiment. FIG. 7A is a graph showing the time change of the air pressure in the secondary air passage 18 during each process of S600 to S1000 when both the air pump 20 and the valve 22 are normal. FIG. 7B is a graph showing the time change of the air pressure in the secondary air passage 18 during each process of S600 to S1000 when the air pump 20 is normal and the valve 22 is deteriorating in performance. The block diagram which shows schematic structure inside ECU28 of a prior art. 9 is a flowchart showing a flow of an abnormality detection operation of the air pump 20 and the valve 22 executed by the ECU 28 in the conventional technique. The graph which shows the time change of the air pressure in the secondary air channel | path 18 in connection with the operation | movement stop (on / off) of the air pump 20, and opening / closing of the valve 22 in a prior art. The chart for demonstrating failure determination of the air pump 20 and the valve | bulb 22 in a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Secondary air supply control apparatus 12 ... Engine 14 ... Exhaust pipe 16 ... Catalytic converter 18 ... Secondary air passage 20 ... Air pump 22 ... Air switching valve 24 ... Pressure sensor 26 ... Warning lamp 28 ... Electronic control device for engine control ( ECU)
30 ... Electromagnetic relay 32 ... In-vehicle battery 36 ... Ignition switch 42 ... Internal power supply IC
44 ... Relay control IC
50 ... Microcomputer 52 ... CPU
54 ... ROM
56 ... RAM
58 ... I / O
60 ... Soak timer IC
68 ... External oscillation element

Claims (10)

A secondary air passage for supplying secondary air to the exhaust gas of the engine;
An air pump for compressing air, the air pump being provided upstream of the secondary air passage;
A valve for opening or closing the secondary air passage, and the valve is provided downstream of the secondary air passage;
Drive control means for performing secondary air supply control for controlling the air pump and the valve to supply air compressed by the air pump from the secondary air passage to the exhaust gas of the engine through the valve; In the provided secondary air supply control device,
Air pressure detecting means for detecting air pressure in the secondary air passage;
An abnormality detecting means for detecting an abnormality of the air pump or the valve based on the air pressure in the secondary air passage detected by the air pressure detecting means ;
A time measuring means for measuring the elapsed time since the engine was stopped;
Starting means for starting the operation of the drive control means and the abnormality detecting means when the elapsed time measured by the time measuring means reaches a predetermined time ,
The drive control means includes
When the engine is stopped, switching between a first state in which the air pump is stopped and the valve is closed, and a second state in which the air pump is operated and the valve is open;
The abnormality detection means includes
By detecting a change in air pressure in the secondary air passage between the first state and the second state, and referring to the detected change in air pressure with a preset change pattern, the air pump or the A secondary air supply control device for determining whether or not a valve is abnormal. The secondary air supply control device according to claim 1,
The drive control means includes
When the engine is stopped, first, the air pump is stopped and the valve is closed to a first state , and then the air pump is operated and the valve is closed to a fourth state.
The abnormality detection means includes
The air pressure in the secondary air passage in the fourth state, the first threshold value set in advance, and the second threshold value set to a value larger than the first threshold value are compared. When the air pressure is less than the first threshold value, the air pump is determined to be unusable. When the air pressure is equal to or greater than the first threshold value and less than the second threshold value, the air pump deteriorates in performance. And determining that the air pump is normal or substantially normal when the air pressure is equal to or greater than a second threshold value. In the secondary air supply control device according to claim 2,
The first threshold value is set to the lowest air pressure necessary for normal secondary air supply control,
The secondary air supply control device, wherein the second threshold value is set to an air pressure obtained by adding a predetermined margin to the first threshold value. In the secondary air supply control device according to any one of claims 1 to 3,
The drive control means includes
When the engine is stopped, first, the air pump is stopped and the valve is closed to a first state , then the air pump is operated and the valve is closed to a fourth state, and then , In the fifth state where the air pump is stopped and the valve is open,
The abnormality detection means includes
Detecting a time change of the air pressure in the secondary air passage in the fourth state and the fifth state, and determining a decrease in performance of the valve based on the time change of the air pressure in each state; Secondary air supply control device. In the secondary air supply control device according to claim 4,
The abnormality detection means includes
Determining whether the valve closes normally or substantially normally based on a time change of air pressure in the secondary air passage in the fourth state;
A secondary air supply control device, wherein whether or not the valve opens normally or substantially normally is determined based on a time change of air pressure in the secondary air passage in the fifth state. In the secondary air supply control device according to any one of claims 1 to 5 ,
A secondary air supply control device comprising storage means for storing a detection result of the abnormality detection means. In the secondary air supply control device according to any one of claims 1 to 6 ,
A secondary air supply control device comprising display means for displaying a detection result of the abnormality detection means. In the secondary air supply control device according to any one of claims 1 to 7 ,
Secondary air, comprising: prohibiting means for prohibiting execution of secondary air supply control by the driving means when the abnormality detecting means detects an abnormality of at least one of the air pump or the valve. Supply control device. The program for functioning a computer system as said each means in the secondary air supply control apparatus of any one of Claims 1-8 . A computer-readable recording medium in which a program for causing a computer system to function as each of the means in the secondary air supply control device according to any one of claims 1 to 8 is recorded.

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