JPH0654103B2 - Exhaust gas recirculation equipment diagnostic equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a diagnostic device for diagnosing whether an exhaust gas recirculation device for an internal combustion engine used in a vehicle such as an automobile is operating normally. .

[Prior Art] An exhaust gas recirculation device incorporated in an internal combustion engine used in a vehicle such as an automobile generally includes an exhaust gas recirculation control valve for exhaust gas recirculation flow rate control and a negative pressure control valve for back pressure control. ,
If the components such as the temperature sensitive valve are broken down, exhaust gas recirculation will not be performed and N
There is a risk that the internal combustion engine will be operated in a state where Ox is not reduced. Even if exhaust gas recirculation is not performed due to a failure, the internal combustion engine can be operated without any problem, and therefore the driver may not notice this and operate for a long period of time, which causes a problem of air pollution.

In view of the above-mentioned problems, there has already been proposed a failure alarm device configured to inform the user of this when exhaust gas recirculation is stopped due to a failure of the exhaust gas recirculation device and to motivate the repair. This is disclosed, for example, in Japanese Utility Model Publication No. 52-9471 and Japanese Utility Model Publication No. 62-71363.

[Problems to be Solved by the Invention] Basically, the failure diagnosis of the exhaust gas circulation device is basically the exhaust gas found by the temperature sensor under the condition that the exhaust gas recirculation is continued for a predetermined time. It may be performed depending on whether or not the temperature of the recirculation passage is equal to or higher than a predetermined value, that is, when the temperature is equal to or lower than the predetermined value, the exhaust gas recirculation device fails because exhaust gas does not flow through the exhaust gas recirculation passage. May be determined to be However, if the judgment temperature used for the judgment as described above is set to a low value, the judgment waiting time is shortened, but on the other hand, the temperature of the exhaust gas recirculation passage is high due to exhaust gas recirculation due to a large flow rate. When a failure occurs in the exhaust gas recirculation device and the exhaust gas recirculation is no longer performed, the failure determination is not performed until the temperature falls below the low determination temperature, and the possibility of erroneous failure determination increases. On the other hand, when the judgment temperature is set to a high value, there are advantages and disadvantages that are completely opposite to those when the judgment temperature is set to a low value, and the judgment waiting time becomes long.

In view of the above problems, it is found that the temperature of the exhaust gas recirculation passage changes, and when the exhaust gas recirculation passage temperature does not rise in the exhaust gas recirculation operation area, it is determined that a failure has occurred in the exhaust gas recirculation device. A failure diagnosis device that does this is considered.

However, during high temperature restart, the exhaust gas recirculation passage temperature may drop in the exhaust gas recirculation operating range depending on the operating conditions of the internal combustion engine thereafter. There is a risk of misdiagnosis.

The present invention has been made in view of the above problems, and an object thereof is to provide a diagnostic device that always and quickly performs a failure diagnosis of an exhaust gas recirculation device.

[Means for Solving the Problems] According to the present invention, the above-described object is to provide an exhaust gas recirculation operation area detection means for detecting whether or not the operation area is an area where exhaust gas recirculation is performed, and exhaust gas recirculation. The temperature detection means for detecting the temperature of the circulation passage, and the temperature detection at the first time point under the condition that the exhaust gas recirculation operation area detection means detects the operation area for exhaust gas recirculation. Whether the temperature detected by the means is the initial temperature and the difference between this temperature and the temperature detected by the temperature detecting means at the second time point when a predetermined time has elapsed from the first time point is greater than or equal to a predetermined value. Failure diagnosis means for diagnosing the failure of the exhaust gas recirculation device based on the above, and an initial stage for reducing and correcting the temperature detected at the first time point when the temperature detected by the temperature detection means is equal to or higher than a predetermined value. With temperature correction means The exhaust gas recirculation device is a diagnostic device.

[Operation and Effect of the Invention] According to the above-described configuration, when the exhaust gas recirculation passage temperature is higher than the predetermined value, the initial temperature used for the temperature difference failure determination is reduced and corrected. Even if the temperature of the exhaust gas recirculation passage decreases, it is avoided that the temperature of the exhaust gas recirculation passage at the second time point becomes lower than the initial temperature, and at this time, a malfunction diagnosis is performed. Is avoided.

[Examples] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows one embodiment of an exhaust gas recirculation device incorporating a diagnosis device according to the present invention.
In the figure, 1 indicates an internal combustion engine, which is
Air is sucked into a combustion chamber 7 through an air cleaner 2, an air flow meter 3, an intake pipe 5 having a throttle valve 4, and an intake manifold 6, and fuel is injected and supplied from a fuel injector 8 to burn burned gas, that is, exhaust gas. Is discharged to the exhaust manifold 9.

The exhaust manifold 9 is provided with an exhaust gas intake port 10 for exhaust gas recirculation, and the intake manifold 6 is provided with an exhaust gas injection port 11, respectively, and the exhaust gas intake port 10 and the exhaust gas injection port 11 are provided. Are connected to each other by an exhaust gas recirculation conduit 12, an exhaust gas recirculation control valve 20, and a conduit 13.

The exhaust gas recirculation control valve 20 has an inlet port 21 and an outlet port 22, the inlet port 21 is communicatively connected to the exhaust gas intake port 10 by a conduit 12, and the outlet port 22 is injected by the conduit 13 with exhaust gas. It is connected to the port 11 for communication. The exhaust gas recirculation control valve 20 has a valve port 23 and a valve element 24, and the valve port 23 is opened and closed by the valve element 24 and its opening degree is controlled to control the exhaust gas recirculation flow rate. ing. Valve element 24
Is connected to the diaphragm 26 of the diaphragm device 25, and when a negative pressure larger than a predetermined value is not introduced into the diaphragm chamber 27, it is pushed down by the spring force of the compression coil spring 28 to close the valve port 23, and the diaphragm chamber 2
When a negative pressure larger than a predetermined value is introduced to 7, the valve port 23 is opened by rising against the spring force of the compression coil spring 28 according to the negative pressure.

The diaphragm chamber 27 of the exhaust gas recirculation control valve 20 has an intake pipe negative pressure extraction provided in the intake pipe 5 via a conduit 29, a back pressure control negative pressure control valve 30, a conduit 31, a temperature sensing valve 32, and a conduit 33. It is communicatively connected to the port 34. As shown in the drawing, the intake pipe negative pressure extraction port 34 is located upstream of the throttle valve 4 in the fully closed position, and is opened when the throttle valve 4 is opened by a relatively small predetermined opening or more. It is provided to be located on the downstream side.

The negative pressure control valve 30 has a valve element 36 for opening and closing the valve port 35 and a diaphragm 37 carrying the valve element. The diaphragm 37 is open to the atmosphere open to the atmosphere on the upper side in the figure. A chamber 38 and a diaphragm chamber 39 on the lower side are respectively defined, and the diaphragm is operated by a compression coil spring 40 when a pressure (positive pressure) higher than a predetermined value is not introduced into the diaphragm chamber 39. The element 36 is located at a position where the valve port 35 is separated from the valve port 35 and the valve port is opened. On the other hand, when a pressure equal to or higher than a predetermined value is introduced into the diaphragm chamber 39, the element is moved upward against the action of the compression coil spring 40. To move the valve element 36 to the valve port 3
5 is brought into contact with the valve 5 to close the valve port.

The diaphragm chamber 39 of the negative pressure control valve 30 includes a pressure chamber 4 between the valve port 23 of the exhaust gas recirculation control valve 20 and an orifice 42 provided downstream of the exhaust gas recirculation control valve 20 by a conduit 41.
3, the exhaust gas pressure in the pressure chamber is introduced.

The structure including the negative pressure control valve 30 and the orifice 42 as described above is a well-known back pressure control mechanism, and in the exhaust gas recirculation operation region where the intake pipe negative pressure is applied to the exhaust gas recirculation control valve 20. , The negative pressure supplied to the diaphragm chamber 27 of the exhaust gas recirculation control valve 20 is adjusted so that the exhaust gas pressure in the pressure chamber 43 is always kept substantially constant, in other words, the opening degree of the valve port 23 is adjusted, As a result, the ratio of the exhaust gas recirculation flow rate to the intake air flow rate, that is, the EGR rate is always kept substantially constant.

The temperature sensitive valve 32 is sensitive to the temperature of the cooling water of the internal combustion engine 1, and closes during the warm-up process in which the temperature of the cooling water is below a predetermined value to shut off the communication between the conduits 31 and 33. On the other hand, when the cooling water temperature is equal to or higher than a predetermined value, the communication between the conduits 31 and 33 is established.

According to the above configuration, the exhaust gas recirculation control valve 20 acts on the conduit 29 with a negative pressure larger than a predetermined value, so that the internal combustion engine 1
When the temperature of the cooling water is equal to or higher than a predetermined value and the temperature sensitive valve 32 is open, the valve is opened, and exhaust gas recirculation is performed at a flow rate according to the valve opening amount. In the figure, reference numeral 50 denotes a microcomputer for controlling the fuel injection amount and for diagnosing the exhaust gas recirculation device. Microcomputer 50
Has a general structure, and has a central processing unit (CP
U) 51, a memory 52, an input port 53, and an output port 54, and the distributor 5 of the internal combustion engine 1
5, the rotation speed sensor 56 provides information about the rotation speed of the internal combustion engine 1, the water temperature sensor 57 provides information about the temperature of the cooling water of the internal combustion engine 1, the airflow meter 3 provides information about the intake air flow rate, Information regarding the temperature of the conduit 10 is given from a temperature sensor 59 provided in the middle of the circulation conduit 13, and the second information is obtained based on the information.
According to the flowchart as shown in the figure, diagnose whether the exhaust gas recirculation device is operating normally,
When it is determined that the exhaust gas recirculation device is not operating normally, the indicator lamp 58 is turned on.

Next, the operation of the diagnosis apparatus according to the present invention will be described with reference to the flow chart shown in FIG.

The routine shown in FIG. 2 is executed as a repetitive interrupt routine at predetermined time intervals. In the first step 10,
Information, that is, various parameters are input from various sensors. After step 10, the process proceeds to step 20.

In step 20, it is determined whether or not the current operating range of the internal combustion engine is the exhaust gas recirculation operating range. Whether or not it is in the exhaust gas recirculation operation range is determined by the intake air flow rate detected by the air flow meter 3 and the rotation speed sensor 56.
Of the internal combustion engine 1 detected by the water temperature sensor 57
It suffices to carry out in accordance with the cooling water temperature of the internal combustion engine 1 detected by the above.

In step 30, the count value C of the counter is incremented by one. After step 30, the process proceeds to step 70.

In step 40, the count value C of the counter is decremented by one. After step 40, the process proceeds to step 50.

At step 50, it is judged if the count value C of the counter is 0 or less. If C <0, go to step 60, otherwise go to step 90.

In step 60, the count value C is set to 0 in order to prevent the count value C of the counter from becoming a negative value of 0 or less.
Is done. After step 60, step 9
Go to 0.

In step 70, the exhaust gas recirculation passage temperature Tegr detected by the temperature sensor 59 is a predetermined maximum value Tmax.
It is determined whether or not the above. When Tegr ≧ Tmax, the exhaust gas recirculation passage Tegr is in a high temperature state. At this time, the routine proceeds to step 80, and when not, to step 90.

In step 80, the initial temperature Tsta of the temperature difference Tdif calculated in step 180 is set to zero. After step 80, the process proceeds to step 110.

At step 90, it is judged if the count value C of the counter is 0 or not. When C = 0, the exhaust gas recirculation is stopped or the exhaust gas recirculation is started. At this time, the process proceeds to step 100, and otherwise, the process proceeds to step 110.

In step 100, at this time, that is, when the exhaust gas recirculation is stopped or when the exhaust gas recirculation is started, the exhaust gas recirculation passage temperature Tegr detected by the temperature sensor 59 is set to the initial temperature Tsta. . Step 100
Then, the process proceeds to step 110.

In step 110, it is judged whether or not it is in the exhaust gas recirculation operation region due to the large flow rate. The determination as to whether or not the exhaust gas recirculation operation range is based on the large flow rate is made by the intake air flow rate detected by the air flow meter 3 and the rotation speed sensor 5.
6 may be performed according to the intake air flow rate detected by 6 and the rotation speed of the internal combustion engine 1 detected by the rotation speed sensor 56, and when the exhaust gas recirculation operation range is the high flow rate, the routine proceeds to step 120. If not, step 130.
Go to.

In step 120, the count value D of the counter is incremented by one. Step 120
Then, the process proceeds to step 160.

In step 130, the count value D of the counter is decremented by one. Step 130
Then, the process proceeds to step 140.

In step 140, the count value D of the counter is 0.
It is determined whether or not the following. If D <0, go to step 150, otherwise go to step 160.
Go to.

In step 150, the count value D of the counter is 0.
The count value D is set to 0 in order to prohibit the following negative values. After step 150, the process proceeds to step 160.

At step 160, it is judged if the count value D of the counter is greater than or equal to a predetermined value Dset. When D ≧ Dset, the internal combustion engine 1 has been operated for a predetermined time or longer in the exhaust gas recirculation operation region with a large flow rate, and at this time, the routine proceeds to step 170.

At step 170, it is judged if the exhaust gas recirculation passage temperature Tegr detected by the temperature sensor 59 is equal to or higher than a predetermined value Tset ₁ . Tset ₁ is the maximum value T
It may be the same value as max, and when Tegr ≧ Tset ₁ , the execution of steps 180 to 200 is prohibited in order to prohibit the execution of the failure determination, while when Tegr ≧ Tset ₁ is not satisfied. Advances to step 180 so that a failure determination can be made.

In step 180, the temperature sensor 59
By subtracting the initial temperature Tsta from the exhaust gas recirculation passage temperature Tegr detected by the above, the temperature Tdif under the temperature is calculated. After step 180, the process proceeds to step 190.

In step 190, the temperature difference Tdif is the predetermined value Tset.
_It is determined whether it is greater than ₂ . Tdif ≧ Tset
_When it is not ₂ , it means that the temperature of the exhaust gas recirculation passage has not risen. At this time, it is determined that the exhaust gas recirculation device is out of order, and the routine proceeds to step 200.

In step 200, the indicator lamp 58 is turned on. The lighting of the indicator lamp 58 allows the driver to know that the exhaust gas recirculation device is out of order.

By performing the diagnosis of the exhaust gas recirculation device according to the above-described flowchart, for example,
As shown in the figure, after hot start of the internal combustion engine,
Even if the exhaust gas recirculation passage temperature Tegr once exceeds the maximum value Tmax and then the internal combustion engine 1 is operated at a low to medium load, the exhaust gas recirculation passage temperature decreases.
Since the initial temperature Tsta of the temperature difference calculation at this time is forcibly corrected to 0 without depending on the exhaust gas recirculation passage temperature Tegr at the time of starting the exhaust gas recirculation, the temperature difference Tdif becomes the exhaust gas recirculation at that time. The value becomes equal to the circulation passage temperature Tegr, and this temperature Tegr does not become smaller than the predetermined value Tset _2. Therefore, erroneous failure determination can be reliably avoided.

In the above, the present invention has been described in detail with reference to specific embodiments, but the present invention is not limited to these.
It will be apparent to those skilled in the art that various embodiments are possible within the scope of the invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of an exhaust gas recirculation device equipped with a diagnosis device according to the present invention,
FIG. 2 is a flow chart showing the operation of the diagnosis device according to the present invention, and FIG. 3 is a graph showing an example of changes in the exhaust gas recirculation passage temperature and a failure determination procedure in the diagnosis device according to the present invention. 1 ... Internal combustion engine, 2 ... Air cleaner, 3 ... Air flow meter, 4 ... Throttle valve, 5 ... Intake pipe, 6
Intake manifold, 7 Combustion chamber, 8 Fuel injector, 9 Exhaust manifold, 10 Exhaust gas intake port, 11 Exhaust gas injection port, 12, 13
...... Conduit, 20 ...... Exhaust gas recirculation control valve, 21 …… Inlet port, 22 …… Outlet port, 23 …… Valve port, 2
4 ... Valve element, 25 ... Diaphragm device, 26 ... Diaphragm, 27 ... Diaphragm chamber, 28 ... Compression coil spring, 29 ... Conduit, 30 ... Negative pressure control valve, 31 ...
… Conduit, 32 …… Temperature sensitive valve, 33 …… Conduit, 34 …… Intake pipe negative pressure extraction port, 35 …… Valve port, Valve port, 36
...... Valve element, 37 ...... Diaphragm, 38 ...... Atmosphere opening chamber, 39 ...... Diaphragm chamber, 40 ...... Compression coil spring, 41 ...... Conduit, 42 ...... Orifice, 43 ...... Pressure chamber, 50 ...... Micro Computer, 51 ... Central processing unit, 52 ... Memory, 53 ... Entrance port, 54
...... Exit port, 55 …… Distributor, 56 ……
… Rotation speed sensor, 57 …… Water temperature sensor, 58 …… Indicator lamp, 59 …… Temperature sensor

Claims (1)

[Claims] 1. Exhaust gas recirculation operating range detecting means for detecting whether or not the operating range is for exhaust gas recirculation, temperature detecting means for detecting a temperature of an exhaust gas recirculating passage, and the exhaust gas recirculating means. The temperature detected by the temperature detecting means at the first time point under the condition that the circulation operating area detecting means detects the exhaust gas recirculation is used as an initial temperature and the first temperature. At the second time point when a predetermined time has passed from the time point, a failure diagnosis is performed to perform a failure diagnosis of the exhaust gas recirculation device based on whether or not the difference from the temperature detected by the temperature detecting means is a predetermined value or more. A diagnostic device for an exhaust gas recirculation device, comprising: means and an initial temperature correction means for reducing and correcting the initial temperature when the temperature detected by the temperature detection means is equal to or higher than a predetermined value.