JPH0689719B2 - Exhaust gas recirculation device diagnostic equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention 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.

BACKGROUND ART An exhaust gas recirculation device incorporated in an internal combustion engine used in a vehicle such as an automobile generally has an exhaust gas recirculation control valve for exhaust gas recirculation flow rate control and a negative pressure control valve for back pressure control,
The temperature sensor, etc. are included, and if a failure occurs in these components, exhaust gas recirculation will not be performed and NO
There is a risk that the internal combustion engine will be operated in the state where x is not reduced. Even if exhaust gas recirculation is not performed due to a failure, the internal combustion engine will operate without any problems, so the driver may run for a long time without noticing this, causing air pollution problems. .

In view of the above-mentioned problems, there has already been proposed a failure alarm device configured to notify 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 in, for example, Japanese Utility Model Publication Nos. 52-9471 and 62-71363.

The failure diagnosis of the exhaust gas recirculation device may be performed by checking whether or not the temperature of the exhaust gas recirculation passage is equal to or higher than a predetermined value under the condition that the exhaust gas recirculation should originally be performed. When the value is less than the value, it may be determined that the exhaust gas recirculation device is out of order because the exhaust gas does not flow through the exhaust gas recirculation passage. However, the actual temperature of the exhaust gas recirculation passage changes due to the repeated execution and stop of the exhaust gas recirculation. Therefore, whether or not the exhaust gas is flowing through the exhaust gas recirculation passage is determined only from the high or low temperature. It is difficult to detect accurately, and it is possible to correctly diagnose the failure of the exhaust gas recirculation device, that is, to diagnose it, simply by determining the temperature of the exhaust gas recirculation passage under the conditions where the exhaust gas recirculation is performed. There is a risk that it will not be done.

In view of this, the operating range in which exhaust gas recirculation is performed, that is, the exhaust gas recirculating operating range is detected at predetermined time intervals from the operating state of the internal combustion engine, and the operating range of the internal combustion engine is the exhaust gas recirculating operating range. At some time, the counter is up-counted, and when the count value of the counter is equal to or higher than the predetermined value, the exhaust gas recirculation passage temperature must be equal to or higher than the predetermined value if the exhaust gas recirculation is normally performed. It has already been considered that the failure determination of the exhaust gas recirculation device is performed depending on whether the exhaust gas recirculation passage temperature is equal to or higher than a predetermined value when the count value is equal to or higher than the predetermined value. This type of diagnostic device is disclosed, for example, in Japanese Utility Model Laid-Open No. 62-71363, and in Japanese Patent Application Nos. 61-235263 and 62-24179 filed by the same applicant as the present applicant. Have already been proposed.

Problems to be Solved by the Invention Speaking of whether the exhaust gas recirculation passage temperature starts rising immediately when exhaust gas recirculation is started, that is not the case.
Even if exhaust gas recirculation is started, the exhaust gas recirculation passage temperature does not rise immediately due to the heat capacity of the conduits, heat conduction to the peripheral parts, etc. Therefore, it immediately rises when exhaust gas recirculation is started. When the count is started, this count value becomes a large value with respect to the actual temperature of the exhaust gas recirculation passage, and the exhaust gas recirculation passage temperature is not always the predetermined value even if this count value is equal to or greater than the predetermined value. No more. When the exhaust gas recirculation is stopped, the temperature of the exhaust gas recirculation passage also drops accordingly. Therefore, when the count value of the counter exceeds a predetermined value, it is judged whether the exhaust gas recirculation device is operating normally or not depending on whether the temperature of the exhaust gas recirculation passage is above the predetermined value. Then, there is a possibility that the exhaust gas recirculation device may be determined to be defective even though it is operating normally.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved exhaust gas recirculation device diagnosis system which solves the above problems.

Means for Solving the Problems According to the present invention, the above-described object is to detect whether or not the operating range of the internal combustion engine is an operating range in which exhaust gas recirculation is performed at predetermined time intervals, and exhaust gas is detected. When it is in the recirculation operation range, the count value of the counter is up-counted, when it is not in the exhaust gas recirculation operation range, the count value of the counter is down-counted, and even if the count value is a predetermined value or more, the exhaust gas recirculation passage If the temperature is not higher than the specified value, it is determined that the exhaust gas recirculation device is out of order.In the diagnosis device of the exhaust gas recirculation device, the operating range of the internal combustion engine is exhausted from the operating range that is not the exhaust gas recirculation operating range. The exhaust gas is provided with up-count prohibiting means for prohibiting up-counting of the counter until a predetermined time elapses from the time when the gas recirculation operation area is changed. This is accomplished by the diagnostic equipment of the recirculation system.

According to the above-mentioned configuration, not only is the count value up-counted when the operating range of the internal combustion engine is the exhaust gas recirculation operating range, but it is also counted when it is not in the exhaust gas recirculation operating range. The count value of the counter is down-counted, and until the predetermined time elapses from the time when the operating area of the internal combustion engine changes from the operating area that is not the exhaust gas recirculation operating area to the exhaust gas recirculation operating area, Up-counting is prohibited, the start of up-counting of the counter is delayed in response to the rise in exhaust gas recirculation passage temperature, and the count value of the counter indicates whether exhaust gas is being recirculated. According to the fluctuation of the exhaust gas recirculation passage temperature under normal operation of the exhaust gas recirculation device. It Therefore, in a situation where the count value is equal to or higher than a predetermined value, the diagnosis of the exhaust gas recirculation device is performed more accurately than before by determining whether or not the exhaust gas recirculation passage temperature is equal to or higher than the predetermined value. Therefore, when the exhaust gas recirculation device is out of order, the failure can be surely determined, and the exhaust gas recirculation device is erroneously determined to be out of order despite the normal operation of the exhaust gas recirculation device. This can be reliably prevented.

Example 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.
10 and exhaust gas injection port 11 are conduits for exhaust gas recirculation
12 and the exhaust gas recirculation control valve 20 and the conduit 13 are connected to each other.

The exhaust gas recirculation control valve 20 has an inlet port 21 and an outlet port 22.
And the inlet port 21 is communicatively connected to the exhaust gas intake port 10 by a conduit 12 and the outlet port 22 is a conduit 13
Is connected in communication with the exhaust gas injection port 11.
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. The valve element 24 is connected to the diaphragm 26 of the diaphragm device 25, and is pushed down by the spring force of the compression coil spring 28 when a negative pressure larger than a predetermined value, for example, −70 mmHg, is not introduced into the diaphragm chamber 27, so that the valve port is closed.
When 23 is closed and a negative pressure larger than a predetermined value is being introduced into the diaphragm chamber 27, a compression coil spring is generated according to the negative pressure.
It rises against the spring force of 28 to open valve port 23.

The diaphragm chamber 27 of the exhaust gas recirculation control valve 20 is connected to the conduit 2
9, negative pressure control valve for back pressure control 30, conduit 31, temperature sensing valve 32, conduit 3
Intake pipe negative pressure extraction port 34 provided in the intake pipe 5 via 3
Connected to. 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, and the diaphragm 37 is an atmosphere release chamber opened to the atmosphere on the upper side in the figure. 38 and a diaphragm chamber 39 on the lower side. Further, the diaphragm is located at a position where the valve element 36 is separated from the valve port 35 by the action of the compression coil spring 40 to open the valve port when the pressure (positive pressure) of the predetermined value or more is not introduced into the diaphragm chamber 39, On the other hand, when a pressure equal to or higher than a predetermined value is introduced into the diaphragm chamber 39, it is displaced upward in the drawing against the action of the compression coil spring 40 to bring the valve element 36 into contact with the valve port 35 and Is located in the closed position.

The diaphragm chamber 39 of the negative pressure control valve 30 has a pressure between the valve port 23 of the exhaust gas recirculation control valve 20 and the orifice 42 provided on the upstream side in the exhaust gas flow direction by the conduit 41. The chamber 43 is connected to communicate with the chamber 43, and 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 range 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 constantly kept almost constant.

The temperature sensitive valve 32 is sensitive to the temperature of the cooling water of the internal combustion engine 1, and is closed during the warm-up process in which the temperature of the cooling water is a predetermined value, for example, 60 ° C. or less, to cut off the communication between the conduits 31 and 33. On the other hand, when the cooling water temperature is equal to or higher than the predetermined value, the communication between the conduits 31 and 33 is established.

According to the configuration as described above, the exhaust gas recirculation control valve 20 acts on the conduit 29 with a negative pressure larger than a predetermined value, for example, a negative pressure larger than -70 mmHg, and the temperature of the cooling water of the internal combustion engine 1 reaches a predetermined value, for example 60. When the temperature-sensitive valve 32 is opened at a temperature equal to or higher than 0 ° C., 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. The microcomputer 50 has a general structure and includes a central processing unit (CPU) 51 and a memory 52.
, An input port 53, an output port 54, and a rotation speed sensor 56 provided in the distributor 55 of the internal combustion engine 1.
More information on the number of revolutions of the internal combustion engine 1 is obtained from the water temperature sensor 57.
More information about the temperature of the cooling water of the internal combustion engine 1, information about the intake air flow rate from the air flow meter 3, and temperature inside the exhaust gas recirculation conduit 13 from the temperature sensor 59, that is, the exhaust gas. Information on the recirculation passage temperature Te is given to each, and on the basis of these information, whether the exhaust gas recirculation device is operating normally is diagnosed according to the flowchart shown in FIG. When it is determined that the 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 every predetermined time, for example, 240 mse.
It is executed as a repeated interrupt routine for each c.

In the first step 10, the temperature in the conduit 13 detected by the temperature sensor 59, that is, the exhaust gas recirculation passage temperature
It is determined whether Te is less than or equal to a predetermined value Teset set in advance. When Te <Teset, the process proceeds to step 20, and when not, that is, when the exhaust gas recirculation passage temperature is equal to or higher than a predetermined value, the process proceeds to step 150.

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, the rotation speed of the internal combustion engine 1 detected by the rotation speed sensor 56, and the internal combustion engine 1 detected by the water temperature sensor 57. It suffices to carry out according to the temperature of the cooling water, and if it is in the exhaust gas recirculation operation region, proceed to step 30, otherwise proceed to step 90.

In step 30, it is judged whether or not the up-count permission flag is set. If the up-count permission flag is set, proceed to step 70,
Otherwise, go to step 40.

In step 40, the count value Y of the counter is incremented by α. After step 40, the process proceeds to step 50.

At step 50, it is judged if the count value Y of the counter is equal to or larger than a predetermined value Yset. If Y> Yset, proceed to step 60, otherwise proceed to step 110.

The predetermined value Yset may be preset to a constant value,
This may be set according to the intake air temperature, the outside air temperature, the cooling water temperature, the exhaust gas recirculation passage temperature, etc., every time the engine is started, or each time the exhaust gas recirculation operation range is newly detected. .

In step 60, the upcount enable flag is set. After step 60, the process proceeds to step 70.

In step 70, the count value X of the other counter is counted up by α. After step 70, the process proceeds to step 80.

In step 80, it is determined whether or not the count value X of the counter is equal to or larger than a predetermined value Xset. If X> Xset, go to step 140, otherwise go to step 150.

Step 90 is executed when the current operating range of the internal combustion engine 1 does not have an exhaust gas recirculation operating range, and in this step 90, the up-count permission flag is reset. After step 90, the process proceeds to step 100.

In step 100, the count value Y of the counter is reset to 0. After step 100, the process proceeds to step 110.

In step 110, the count value X of the other counter is down counted by β. After step 110, the process proceeds to step 120.

At step 120, it is judged if the count value X of the counter is greater than zero. If X> 0, go to step 150, otherwise go to step 130.

In step 130, the count value X of the counter is set to 0. After step 130, the process proceeds to step 150.

In step 140, it is determined that the exhaust gas recirculation device is out of order, and the indicator lamp 58 is turned on.

In step 150, it is determined that the exhaust gas recirculation device has not failed, and the indicator lamp 58 is turned off.

By performing the diagnosis of the exhaust gas recirculation device according to the above-described flowchart, the count value X of the counter is determined by the predetermined value Yset of the count value Y even when the operating range of the internal combustion engine becomes the exhaust gas recirculation operating range. The count value X is up-counted with a delay, so that the degree of increase of the count value X is adapted to the degree of increase of the exhaust gas recirculation passage temperature Te detected by the temperature sensor 59, whereby the count value X is set to a predetermined value Xset. In the above situation, the failure of the exhaust gas recirculation device is determined based on the exhaust gas recirculation passage temperature, and accurate diagnosis is performed.

In FIG. 2 of the present embodiment, step 20 is a step for detecting whether or not it is the operating range for exhaust gas recirculation according to the present invention.
Reference numerals 70 and 110 respectively count up the count value X of the counter when it is in the exhaust gas recirculation operation range and downcount the count value X of the counter when it is not in the exhaust gas recirculation operation range. 14
0 is for the failure determination of the exhaust gas recirculation device, steps 40 and 5
0 corresponds to up-count prohibiting means for prohibiting up-counting of the counter.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of an exhaust gas recirculation device incorporating a diagnosis device according to the present invention,
FIG. 2 is a flowchart showing the operation of 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, 24 …… 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, 36 …… Valve element, 37 …… Diaphragm, 38…
… Atmosphere open chamber, 39 …… Diaphragm chamber, 40 …… Compression coil spring, 41 …… Conduit, 42 …… Orifice, 43 …… Pressure chamber, 50…
… Microcomputer, 51 …… Central processing unit, 52…
… Memory, 53 …… input port, 54 …… output port, 55 ……
Distributor, 56 ... Rotation speed sensor, 57 ... Water temperature sensor, 58 ... Indicator lamp, 59 ... Temperature sensor

Claims (1)

[Claims] 1. A method for detecting whether or not the operating range of an internal combustion engine is an operating range in which exhaust gas recirculation is carried out, and when the operating range is in the exhaust gas recirculation operating range, the count value of a counter is counted up. When the exhaust gas recirculation operation range is not reached, the count value of the counter is down-counted, and the exhaust gas recirculation passage temperature fails if the exhaust gas recirculation passage temperature is equal to or higher than the predetermined value. In the diagnosis device of the exhaust gas recirculation device that determines that the predetermined period of time has elapsed from the time when the operating range of the internal combustion engine changes from the operating range that is not the exhaust gas recirculation operating range to the exhaust gas recirculation operating range Up to a counter having an up-count prohibiting means for prohibiting up-counting of the counter.