JP2000291494A - Anomaly detection device for engine exhaust gas recirculation system - Google Patents

Abstract

(57) [Summary] To further expand opportunities for abnormality detection of an EGR device. An exhaust gas recirculation device (EGR) for an engine (1) is provided.
The device 31 includes an EGR passage 32, an EGR valve 33, and a VS.
VS34. The abnormality detection device includes a throttle sensor 20 for detecting a throttle opening and an intake pressure sensor 22 for detecting an intake pressure. Electronic control unit (ECU) 3
A value of 0 controls the VSV 34 to switch between the execution and the stop of the EGR, and compares the intake pressure difference detected before and after the switching with the determination value to determine the abnormality of the device 31. The ECU 30 sets an operation range in which the intake pressure difference is small as a limit range for abnormality determination,
Throttle opening and intake pressure do not fall within the limit range,
When the throttle change amount corresponds to the first degree of stability, the abnormality determination is permitted. Further, when the throttle opening and the intake pressure fall within the limit range, the ECU 30 further allows the abnormality determination when the throttle change amount corresponds to the second stability having a smaller change than the first stability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation system in which part of exhaust gas discharged from a combustion chamber of an engine flows to an intake passage and is recirculated to the combustion chamber. More particularly, the present invention relates to an abnormality detection device for an exhaust gas recirculation device of an engine that detects an abnormality generated in the exhaust gas recirculation device.

[0002]

2. Description of the Related Art Conventionally, there is a well-known exhaust gas recirculation (exhaust gas recirculation: EGR) device used for, for example, a gasoline engine or a diesel engine mounted on an automobile. This EGR device generally lowers the combustion temperature of the fuel in the combustion chamber by flowing a part of the exhaust gas discharged from the combustion chamber to the exhaust passage to the intake passage and recirculating the exhaust gas to the exhaust gas. Nitrogen oxide (NOx) contained is reduced.

[0003] This type of EGR device generally includes an EGR passage for flowing a part of exhaust gas discharged from a combustion chamber from an exhaust passage to an intake passage, and an EGR passage for adjusting EGR.
An EGR valve provided in the R passage. For example, there is a diaphragm type EGR valve that selectively opens and closes by selectively introducing a negative pressure and an atmospheric pressure as an operating pressure. Further, there is an EGR vacuum switching valve (EGRVSV) provided in association with the diaphragm type EGR valve. This EGRVSV is E
It is electrically controlled to adjust the negative pressure and the atmospheric pressure introduced into the diaphragm chamber of the GR valve. In the EGR device configured as described above, the amount of EGR recirculated to the combustion chamber through the EGR passage and the intake passage is adjusted by duty control of the opening of the EGR valve in accordance with the operating state of the engine. .

In this type of EGR device,
For example, the EGR valve is damaged, the valve body is stuck, or E
When an abnormality such as breakage or clogging of the GR passage occurs, the amount of EGR recirculated to the combustion chamber may be insufficient or excessive. Here, when the EGR amount is insufficient, the NO contained in the exhaust gas of the engine
x may increase, and when the EGR amount becomes excessive, a misfire may occur to increase the emission of unburned gas or incompletely burned gas. This type of abnormality has little effect on the operating performance of the engine, and therefore is often not noticed by the driver.

[0005] Therefore, various methods and devices have been proposed which detect an abnormality of the EGR device in real time so that a driver or the like can recognize such an abnormality at an early stage and take necessary measures. As a conventional technique related to this type of abnormality detection, a difference between a pressure (intake pressure) in an intake passage between when an EGR device executes EGR and when the EGR is temporarily stopped when an engine is in a steady operation state. In some cases, an abnormality of the EGR device is detected by calculating (intake air pressure difference) and comparing the intake air pressure difference with a predetermined determination value, and a driver is alerted of the abnormality. When the EGR device is normal, the EGR is temporarily stopped when the EGR is performed, so that the exhaust gas flowing into the intake passage through the EGR passage is cut off, and the intake pressure is temporarily reduced accordingly. Become. However, when the above-described abnormality occurs in the EGR device, the exhaust gas flowing into the intake passage through the EGR passage becomes excessive or deficient, so that the intake pressure difference becomes smaller than a predetermined determination value. . Using this principle, an abnormality of the EGR device is detected. JP-A-4-365962 and JP-A-5
Japanese Patent Publication No. 231245 discloses an example of an abnormality detection device employing this kind of principle.

Here, in order to execute the above-described conventional abnormality detection, it is a prerequisite that the operating state of the engine is in a range in which the intake pressure difference due to the execution / stop of the EGR is substantially manifested. For example, a throttle valve provided in the intake passage is in a low opening range where the opening (throttle opening) approaches fully closed, or a middle opening position where the throttle valve is opened to some extent and the intake pressure approaches atmospheric pressure. Within this range, the intake pressure difference becomes relatively small or substantially invisible. For this reason, a range of the operating state in which the intake pressure difference is substantially manifested is required as a precondition. In addition, the steady state of the operating state of the engine is a prerequisite for executing abnormality detection. This is EGR
Is to accurately detect the difference between the intake pressures caused by the execution / stop of the engine, distinguishing from the change in the intake pressure caused by the difference in the operation state of the engine. That is, in a transient state in which the throttle opening greatly changes, or in a state close to such a transient state, the intake pressure also largely changes with a change in the throttle opening. Even if an attempt is made to detect an intake pressure difference due to execution / stop of EGR in such an operating state, the value cannot be detected accurately. On the other hand, when the operating state of the engine is in a steady state where the change in the throttle opening is small, the intake pressure is stabilized to some extent. Therefore, in such a steady state, only the intake pressure difference due to the execution / stop of the EGR can be accurately detected, and the abnormality of the EGR device can be accurately detected.

FIG. 14 shows a change in the intake pressure with respect to the throttle opening when the EGR is performed and when the EGR is stopped. In the graph, a broken curve indicates a change in the intake pressure when the EGR is performed, and a solid curve indicates a change in the intake pressure when the EGR is stopped. As is clear from this graph, in a certain range of the throttle opening, the intake pressure during the execution of EGR becomes higher than that when the EGR is stopped, and in the other ranges, the two become the same. Conventionally, in this graph, the EGR device has a throttle opening within a range where the throttle opening is a predetermined set value B to a set value C (the set value B is defined by the throttle opening and the set value C is defined by the intake pressure). Anomaly detection was being performed. Here, as the set value B, for example, “10 deg”
Can be applied. The set value C is correlated with a throttle opening larger than the set value B, and for example, an intake pressure equivalent to “atmospheric pressure-200 mmHg” can be applied. The abnormality detection of the EGR device is performed in the range of the set values B to C because the difference in intake pressure due to the execution / stop of the EGR is sufficiently larger than the change in intake pressure that occurs when the operation of the engine is in a steady state. Because. That is, a signal-to-noise ratio (S / N) sufficient for the intake pressure difference for abnormality detection can be secured. Accordingly, a low opening side where the throttle opening is smaller than the set value B, and
On the middle and high opening side where the intake pressure becomes larger than the set value C, E
Since a sufficient S / N cannot be obtained for the intake pressure difference due to the execution / stop of the GR, the abnormality detection of the EGR device has been limited.

[0008]

However, in the above-described abnormality detection of the conventional EGR device, the detection is only allowed within a detection range between the set value B and the set value C. Therefore, there is a tendency that the chance of detecting an abnormality is relatively reduced. Since the chance of detecting the abnormality of the EGR device is reduced, even if there is an abnormality in the EGR device, it cannot be detected at an early stage.
x or unburned gas emission may be increased.

On the other hand, even when the operating state of the engine is in a steady state and is within a detection range in which abnormality detection of the EGR device can be permitted, the throttle opening may slightly increase or decrease. At this time, the change in the intake pressure with respect to the change in the throttle opening tends to be relatively large as the throttle opening is small or the engine rotational speed is low. For this reason, in order to more accurately evaluate the intake pressure difference in order to more accurately detect the abnormality of the EGR device, the intake pressure difference or its determination value is corrected in accordance with such a throttle opening or the engine speed. There is a need.

Similarly, when the operating state of the engine is in a steady state and is within a detection range in which abnormality detection can be tolerated,
When the throttle opening slightly increases or decreases, the change in the intake pressure may slightly differ depending on the direction of the minute increase or decrease of the throttle opening, that is, whether the throttle opening moves in the opening direction or the closing direction. Therefore, in order to more accurately evaluate the intake pressure difference in order to more accurately detect the abnormality of the EGR device, it is necessary to correct the intake pressure difference or its determination value based on such a small change in the throttle opening. is there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to detect an abnormality in an EGR device by evaluating a difference in intake state due to switching between execution and stop of EGR. It is an object of the present invention to provide an abnormality detection device for an exhaust gas recirculation device of an engine, which makes it possible to further expand opportunities for detecting an abnormality of an EGR device.

[0012]

In order to achieve the above object, according to the first aspect of the present invention, a part of exhaust gas discharged from a combustion chamber of an engine flows to an intake passage and is returned to the combustion chamber. A recirculation passage for circulating, and recirculation adjusting means for adjusting the flow of exhaust gas in the recirculation passage; and Operating state detection means provided for an exhaust gas recirculation device adapted to recirculate to the combustion chamber, for detecting an operation state of the engine, and intake state detection means for detecting an intake state in an intake passage; When the recirculation adjusting means is controlled to recirculate the exhaust gas to the combustion chamber, the control of the recirculation adjusting means is switched to temporarily stop the recirculation of the exhaust gas, and the switching is performed. Abnormality for the engine exhaust gas recirculation device, comprising: abnormality judgment means for judging the abnormality of the exhaust gas recirculation device by comparing the difference of the intake state detected before and after with the predetermined judgment value. In the detection device, the range of the operating state of the engine corresponding to the relatively small difference in the intake state is specified as a limited range for limiting the determination by the abnormality determining means, and the detected operating state is determined to correspond to the limited range. And a first judgment permitting means for permitting the judgment by the abnormality judging means when in a steady state corresponding to the first stability, and in a case where the detected operating state falls within the limit range. When the detected operating state is in the steady state corresponding to the second stability, which has a smaller change than the first stability, the second determination permission for permitting the determination by the abnormality determination means. And the spirit that was a stage.

In the above construction, a part of the exhaust gas discharged from the combustion chamber of the engine flows through the recirculation passage, is introduced into the intake passage, is recirculated again to the combustion chamber, and is used for combustion. Here, by controlling the recirculation adjusting means, the flow of the exhaust gas in the recirculation passage is adjusted, and the amount of the exhaust gas introduced into the intake passage is increased or decreased or stopped. By adjusting the amount of exhaust gas introduced into the intake passage as described above, the intake state in the intake passage, for example, the intake pressure or the intake amount is affected and changed in a specific engine operating state. The abnormality detection device for the exhaust gas recirculation device detects the abnormality of the exhaust gas recirculation device by utilizing the change in the intake state. That is, when the recirculation adjusting means is controlled to recirculate the exhaust gas to the combustion chamber (when the introduction of the exhaust gas to the intake passage is permitted), the exhaust gas is recirculated (the exhaust gas is recirculated to the intake passage). The control of the recirculation adjusting means is switched by the abnormality determining means in order to temporarily stop the introduction), and the difference between the intake states in the intake passage detected by the intake state detecting means before and after the switching is determined by the abnormality determining means. By being compared with a predetermined judgment value by
An abnormality in the exhaust gas recirculation device is determined. Here, the judgment by the abnormality judging means is, as a premise, permitted by the first judgment permitting means only under predetermined conditions. That is, the range of the operating state of the engine corresponding to the relatively small difference between the intake states is specified as the limited range that limits the determination by the abnormality determination unit. If the operating state of the engine detected by the operating state detecting means does not fall within the above-mentioned limited range and is in a steady state corresponding to the first degree of stability, the determination by the abnormality determining means is made to the first state. It will be permitted by the judgment permitting means. On the other hand, even if the operating state of the engine detected by the operating state detecting means falls within the above-mentioned limit range, that is, even if the difference between the intake states is relatively small, the detected engine state When the operating state corresponds to the second stability having a smaller change than the first stability, the determination by the abnormality determining means is permitted by the second determination permitting means. Therefore, by adding the judgment by the second judgment permitting means, the opportunity of judgment by the abnormality judging means becomes
The number increases as compared with the case where only the first judgment permitting means permits.

In order to achieve the above object, according to a second aspect of the invention, in the configuration of the first aspect, at least one of the first stability and the second stability is detected. It is intended that a stability calculating means for calculating according to the driving state is provided.

According to the configuration of the present invention, in addition to the operation of the first aspect of the present invention, the first stability and the second stability adapted to the difference in the operating state of the engine can be obtained. Therefore, even in the above-mentioned limited range, the difference in the intake state caused by the switching of the introduction of the exhaust gas into the intake passage is more clearly distinguished from the difference in the intake state caused by the change in the operating state, and the exhaust gas recirculation device Abnormalities are more accurately determined.

According to a third aspect of the present invention, in the configuration of the first or second aspect, a determination value to be compared with a difference between intake states is detected. It is intended that a determination value calculating means for calculating according to the driving state is provided.

According to the configuration of the present invention, in addition to the operation of the first or second aspect of the present invention, a judgment value suitable for a difference in the operating state of the engine can be obtained. Therefore, the magnitude of the difference in the intake state caused by the switching of the introduction of the exhaust gas to the intake passage is determined more appropriately,
The abnormality of the exhaust gas recirculation device can be determined more accurately.

According to a fourth aspect of the present invention, a determination value to be compared with a difference between intake states is detected. It is intended that a determination value calculating means for calculating according to a small increase / decrease change in the operating state is provided.

According to the configuration of the present invention, in addition to the effect of one of the first to third aspects of the present invention, it is possible to obtain a judgment value suitable for a small difference in increase and decrease in the operating state of the engine. Therefore, the magnitude of the difference between the intake states caused by the switching of the introduction of the exhaust gas into the intake passage is determined more appropriately, and the abnormality of the exhaust gas recirculation device is more accurately determined.

According to a fifth aspect of the present invention, there is provided a recirculation passage for flowing a part of exhaust gas discharged from a combustion chamber of an engine to an intake passage and recirculating the exhaust gas to the combustion chamber. And recirculation adjusting means for adjusting the flow of exhaust gas in the recirculation passage. The exhaust gas is recirculated to the combustion chamber through the recirculation passage and the intake passage by controlling the recirculation adjustment means. Operating state detecting means for detecting the operating state of the engine, intake state detecting means for detecting the intake state in the intake passage, and exhaust gas to the combustion chamber. When the recirculation adjusting means is controlled to recirculate, the control of the recirculation adjusting means is switched to temporarily stop the recirculation of the exhaust gas, and detected before and after the switching. An abnormality detection device for an exhaust gas recirculation device of an engine, comprising: abnormality determination means for determining an abnormality of the exhaust gas recirculation device by comparing a difference between intake states with a predetermined determination value. The purpose of the present invention is to provide a determination value calculating means for calculating a determination value to be compared with the difference between the two according to the detected operating state.

According to the configuration of the present invention, a judgment value suitable for a difference in the operating state of the engine can be obtained. Therefore, the magnitude of the difference between the intake states caused by the switching of the introduction of the exhaust gas into the intake passage is determined more appropriately, and the abnormality of the exhaust gas recirculation device is more accurately determined.

According to a sixth aspect of the present invention, there is provided a recirculation passage for flowing a part of exhaust gas discharged from a combustion chamber of an engine to an intake passage and recirculating the exhaust gas to the combustion chamber. And recirculation adjusting means for adjusting the flow of exhaust gas in the recirculation passage. The exhaust gas is recirculated to the combustion chamber through the recirculation passage and the intake passage by controlling the recirculation adjustment means. Operating state detecting means for detecting the operating state of the engine, intake state detecting means for detecting the intake state in the intake passage, and exhaust gas to the combustion chamber. When the recirculation adjusting means is controlled to recirculate, the control of the recirculation adjusting means is switched to temporarily stop the recirculation of the exhaust gas, and detected before and after the switching. An abnormality detection device for an exhaust gas recirculation device of an engine, comprising: abnormality determination means for determining an abnormality of the exhaust gas recirculation device by comparing a difference between intake states with a predetermined determination value. The purpose of the present invention is to provide a determination value calculating means for calculating a determination value to be compared with the difference in accordance with a small increase / decrease change in the detected operating state.

According to the configuration of the present invention, it is possible to obtain a judgment value suitable for a small difference in increase / decrease in the operating state of the engine. Therefore, the magnitude of the difference between the intake states caused by the switching of the introduction of the exhaust gas into the intake passage is determined more appropriately, and the abnormality of the exhaust gas recirculation device is more accurately determined.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention (the first aspect of the present invention) embodying an abnormality detection device for an exhaust gas recirculation device of an engine. Will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of an engine system mounted on an automobile. The engine 1 is of a multi-cylinder type having a known structure, and in this embodiment,
The engine 1 having four cylinders # 1 to # 4 is employed. The engine 1 explodes and burns fuel and air supplied through the intake passage 2, that is, a combustible air-fuel mixture in the combustion chambers of the cylinders # 1 to # 4, and discharges the exhaust gas after the combustion through the exhaust passage 3. As a result, a piston (not shown) is driven, and the crankshaft 4
Is rotated to obtain power.

The throttle valve 5 provided in the intake passage 2 is opened and closed to adjust the amount of air (intake amount) that flows through the passage 2 and is taken into each of the cylinders # 1 to # 4. The valve 5 operates in conjunction with the operation of an accelerator pedal 6 provided in the driver's seat. The throttle sensor 20 provided for the throttle valve 5
The opening degree (throttle opening degree) TA of this valve 5 is detected,
It outputs an electric signal corresponding to the detection signal.
An intake air temperature sensor 21 provided at the entrance of the intake passage 2 detects the temperature (intake air temperature) THA of the air taken into the intake passage 2 and outputs an electric signal corresponding to the detected signal. An intake pressure sensor 22 provided in the intake passage 2 detects an intake pressure PM in the intake passage 2 downstream of the throttle valve 5 and outputs an electric signal corresponding to the detected signal.

A plurality of injectors 7 provided at the intake ports corresponding to each of the cylinders # 1 to # 4 are connected to each of the cylinders # 1 to # 4.
For injecting and supplying fuel. These injectors 7 are provided on a common delivery pipe 8. The delivery pipe 8 is for distributing the fuel pumped from the fuel tank 9 to each of the injectors 7.

A plurality of spark plugs 10 provided in the engine 1 corresponding to each of the cylinders # 1 to # 4 operate upon receiving an ignition signal distributed from the distributor 11. The distributor 11 distributes the high voltage output from the igniter 12 to each spark plug 10 in accordance with the change in the rotation angle of the crankshaft 4, that is, the "crank angle (° CA)". The operation timing of each ignition plug 10, that is, the ignition timing is determined by the output timing of the high voltage output from the igniter 12. Therefore, by controlling the igniter 12, the ignition timing of each of the ignition plugs 10 in each of the cylinders # 1 to # 4 is controlled.

The oxygen sensor 23 provided in the exhaust passage 3
Detects the oxygen concentration Ox in the exhaust gas discharged from each of the cylinders # 1 to # 4 to the passage 3, and outputs an electric signal corresponding to the detected signal.

The rotational speed sensor 24 provided in the distributor 11 detects the angular speed of the crankshaft 4, that is, the engine rotational speed NE, and outputs an electric signal corresponding to the detected signal. The distributor 11 incorporates a rotor (not shown) that rotates in conjunction with the rotation of the crankshaft 4 and has a plurality of teeth on the outer periphery. The rotation speed sensor 24 includes the rotor and an electromagnetic pickup (not shown) arranged on the outer periphery of the rotor. Each time the electromagnetic pickup detects the passage of each tooth with the rotation of the rotor, the rotation speed sensor 24 outputs one pulse signal. In this embodiment, every time the crank angle advances by 30 ° CA,
One pulse signal is output from the rotation speed sensor 24. Similarly, the distributor 11 is provided with a cylinder discrimination sensor 25 for detecting a change in the crank angle at a predetermined rate according to the rotation of the rotor. In this embodiment, the crankshaft 4 is driven by 2 until all of the first cylinder # 1 to the fourth cylinder # 4 sequentially end the combustion stroke.
One pulse signal as the reference position signal GS is output from the cylinder discrimination sensor 25 at a rate of 720 ° CA as a rotation.

The water temperature sensor 26 provided in the engine 1
Temperature (cooling water temperature) T of cooling water flowing inside the engine 1
HW is detected, and an electric signal corresponding to the detection signal is output.

In this embodiment, the throttle sensor 20, the intake air temperature sensor 21, the intake pressure sensor 22,
The oxygen sensor 23, the rotation speed sensor 24, the cylinder discrimination sensor 25, the water temperature sensor 26, and the like constitute an operating state detecting means of the present invention for detecting the operating state of the engine 1.
Further, the intake pressure sensor 22 corresponds to intake state detection means of the present invention for detecting an intake state in the intake passage 2.

The above-described injectors 7, the delivery pipe 8, the fuel tank 9 and the like constitute a fuel supply device. The electric fuel pump 13 built in the fuel tank 9 pumps up and discharges the fuel stored in the tank 9. The fuel pipe 14 connected to the discharge port side of the fuel pump 13 is connected to the delivery pipe 8 via the fuel filter 15. Here, when the fuel pump 13 operates, the fuel in the fuel tank 9 is discharged from the pump 13 to the fuel pipe 14, and after the foreign matter is removed by the fuel filter 15, the fuel is pumped to the delivery pipe 8. Is distributed to each injector 7. The fuel pumped to the injectors 7 is injected into the intake ports as the injectors 7 operate, and supplied to the cylinders # 1 to # 4.

The exhaust gas recirculation (EGR) device 31 allows a part of the exhaust gas discharged from the combustion chambers of the cylinders # 1 to # 4 to the exhaust passage 3 to flow into the intake passage 2 and recirculates to each combustion chamber. It is to make it. The EGR device 31 includes an EGR passage 32 connected between the intake passage 2 and the exhaust passage 3.
An EGR valve 33 provided in the EGR passage 32;
An EGR vacuum switching valve (EGRV) electrically controlled to operate the EGR valve 33
SV) 34 and an EGR vacuum modulator (EG)
RVM) 35.

One end of the EGR passage 32 communicates with the intake passage 2 downstream of the throttle valve 5, and the other end communicates with the exhaust passage 3. The EGR passage 32 is for flowing a part of the exhaust gas discharged from each combustion chamber of the engine 1 to the exhaust passage 3 to the intake passage 2 and recirculating the exhaust gas to each combustion chamber. Is equivalent to The EGR valve 33 adjusts the flow of the exhaust gas in the EGR passage 32, that is, the EGR. This EGR
The valve 33 is a diaphragm valve that selectively opens and closes by selectively introducing a negative pressure and an atmospheric pressure as an operating pressure. The EGR valve 33 includes a diaphragm chamber defined by a diaphragm, a valve body fixed to the diaphragm, and a spring for urging the valve body in a direction in which the EGR passage 32 is closed.

The EGR VSV 34 is electrically controlled to adjust the negative pressure and the atmospheric pressure introduced into the diaphragm chamber of the EGR valve 33. The input port of the EGR VSV 34 is connected to the upstream side of the throttle valve 5 via the pipe 36, and the output port is connected to the diaphragm chamber of the EGR valve 33. This EGRVSV34 is
Duty control is performed to open the EGR valve 33 at a predetermined opening.

The EGR VM 35 is for smoothing the negative pressure introduced into the diaphragm chamber of the EGR valve 33. Two input ports of the EGR VM 35 are connected to the upstream side of the throttle valve 5 via pipes 37 and 38, and an output port is connected to the EGR valve 3 through a pipe 39.
3 EGR passage 32.

Atmospheric pressure is introduced into the ports of the pipes 36 to 38 communicating with the intake passage 2 when the throttle valve 5 is closed, and negative intake pressure is introduced when the throttle valve 5 is opened to a certain opening. Is done.

Here, when the throttle valve 5 is opened to a certain opening, the EGR VSV 34 is electrically turned on, so that the intake negative pressure is introduced into the diaphragm chamber of the EGR valve 33. Due to the introduction of the intake negative pressure, the diaphragm of the EGR valve 33 is displaced upward against the urging force of the spring, the valve body moves upward, and the EGR passage 32 is opened. That is, the EGR valve 33 opens and the EGR passage 3
2, the exhaust gas flows to the intake passage 2 and is recirculated to each combustion chamber. That is, EGR is performed. On the other hand, when the EGR VSV 34 is electrically turned off, the atmospheric pressure is introduced into the diaphragm chamber of the EGR valve 33. With the introduction of the atmospheric pressure, the EGR valve 33
The diaphragm is displaced downward by the urging force of the spring, and its valve body moves downward, so that the EGR passage 32 is closed.
That is, the EGR valve 33 closes and the flow of the exhaust gas in the EGR passage 32 stops. That is, the EGR is stopped.

In this embodiment, a warning lamp 16 which is turned on when an abnormality of the EGR device 31 is detected is provided in a driver's seat of an automobile (not shown). In the driver's seat, a well-known ignition switch (not shown)
Is provided. The engine 1 is started by operating a starter (not shown) by operating this switch.

In this embodiment, an electronic control unit (EC
U) 30 is the aforementioned throttle sensor 20, intake temperature sensor 21, intake pressure sensor 22, oxygen sensor 23, rotation speed sensor 24, cylinder discrimination sensor 25, and water temperature sensor 26.
Input various signals output from the above. The ECU 30
In order to execute fuel injection control including air-fuel ratio control, ignition timing control, EGR control, and abnormality detection control based on these input signals, each injector 7 and igniter 1
2. The warning lamp 16 and the EGRVSV 34 are respectively controlled. In this embodiment, the ECU 30 constitutes the abnormality determination means, the first determination permission means, and the second determination permission means in the first aspect of the invention.

As is well known, the ECU 30 includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), a backup RAM, an external input circuit, an external output circuit, and the like. The ECU 30
A logical operation circuit is configured by connecting a CPU, a ROM, a RAM, a backup RAM, an external input circuit, an external output circuit, and the like by a bus. The ROM stores a predetermined control program relating to the various controls in advance. The RAM temporarily stores the calculation results of the CPU. The backup RAM stores data stored in advance. The CPU executes the above-described various controls and the like according to a predetermined control program based on detection signals of the various sensors 20 to 26 input via the input circuit.

Here, the ignition timing control is to control the ignition timing of each ignition plug 10 by controlling the igniter 12 according to the operating state of the engine 1. The fuel injection control is to control the amount of fuel injected from each injector 7 (fuel injection amount) and the timing of the injection in accordance with the operating state of the engine 1. The air-fuel ratio control is to feedback-control the air-fuel ratio of a combustible mixture of fuel and air supplied to the engine 1 based on at least a detection signal of the oxygen sensor 23.

The EGR control is to control the EGR for each combustion chamber through the EGR passage 32 and the intake passage 2 by controlling the EGR VSV 34 and the EGR valve 33 according to the operation state of the engine. The EGR abnormality detection control means that when the EGR VSV 34 and the EGR valve 33 are controlled and the EGR is being performed, the EGR VSV 34 and the EGR valve 3 are used to temporarily stop the EGR.
3 is switched. Then, by comparing the difference between the values of the intake pressure PM detected before and after the switching with a predetermined determination value, it is determined that the EGR device 31 is abnormal, and the warning lamp 16 is controlled. Here, the abnormality of the EGR device 31 includes a failure of the EGR valve 33 including a broken diaphragm and a sticking of a valve element, a failure of the EGRVSV 34, a failure of the EGRVM 35, a clogging or breakage of the EGR passage 32, and the like.

Next, among the various controls executed by the ECU 30, the processing contents of the abnormality detection control for the EGR device 31 will be described. FIG. 2 shows a flowchart relating to the abnormality detection control.

The ECU 30 periodically executes the routine shown in FIG. 2 at predetermined time intervals. First, step 100
The ECU 30 has the intake air temperature sensor 21 and the intake pressure sensor 2
2. Based on detection signals from the rotation speed sensor 24 and the water temperature sensor 26, the intake air temperature THA, the cooling water temperature THW, and the atmospheric pressure P
The value of A is read. Here, as the value of the atmospheric pressure PA, the value of the intake pressure PM detected between the time the ignition switch is turned on and the time the starter is started is used. Thereafter, the value of the atmospheric pressure PA is corrected based on the values of the throttle opening TA and the engine speed NE during operation.

In step 110, the ECU 30 determines whether a precondition for detecting an abnormality in the EGR device 31 is satisfied. Here, preconditions for abnormality detection include that the warm-up of the engine 1 has been completed and that the EGR device 31 is controlled to perform EGR. The ECU 30 proceeds to step 120 after waiting for the precondition for the abnormality detection to be satisfied.

In step 120, the ECU 30 reads the values of the throttle opening TA, the intake pressure PM, and the engine speed NE based on the detection signals of the throttle sensor 20, the intake pressure sensor 22, and the rotational speed sensor 24, respectively.

Next, at step 130, the ECU 30
The value of the read throttle opening TA is a predetermined set value A.
It is determined whether the value is larger and the read value of the intake pressure PM is smaller than a predetermined set value D. Here, the set values A and D are shown in the graph of FIG. 3 according to FIG. 14 described above. In the present embodiment, all the setting values A and D related to the abnormality detection defined according to the operating state of the engine 1 are set. This shows the range (entire detection range) S0. Throttle opening TA
On the low opening side (the side where the negative pressure of the intake pressure PM is large), a set value A is provided to define the entire detection range S0 with the throttle opening TA. For example, “5d
eg). On the other hand, on the middle and high opening side of the throttle opening TA (the side where the negative pressure of the intake pressure PM is small), a set value D is provided to define the entire detection range S0 by the intake pressure PM. As this set value D, for example, “PA
−120 mmHg ”can be applied. The entire detection range S0 is wider than the conventional detection range S1 defined by the above-described set value B and set value C.
In the intake pressure PM at the time of EGR execution indicated by the broken curve,
This is included in a range that is higher than the intake pressure PM at the time of EGR stop indicated by the solid curve. If the determination result in step 130 is negative, the ECU 30 returns the process to step 120 on the assumption that the operating state of the engine 1 is not included in the entire detection range S0. If the result is affirmative,
The ECU 30 proceeds to step 140 assuming that the operating state is included in the entire detection range S0.

In step 140, the change amount (throttle change amount) ΔTA of the throttle opening TA per unit time is calculated based on the previously read throttle opening TA and the presently read throttle opening TA. I do.
The throttle change amount ΔTA indicates whether the operation state of the engine 1 is in a stable steady state or in a change state accompanied by an acceleration tendency and a deceleration tendency.

Thereafter, at step 150, the ECU 30
Determines whether the read value of the throttle opening TA is larger than a predetermined set value B and the read value of the intake pressure PM is smaller than a predetermined set value C. here,
Each of the set values B and C is shown in the graph of FIG. 3 described above, and defines a conventional detection range S1 that is narrower than the entire detection range S0. On the low opening side of the throttle opening TA (on the side where the negative pressure of the intake pressure PM is large), a set value B is provided to define the conventional detection range S1 by the throttle opening TA. As the set value B, for example, “10
deg ". On the other hand, the middle degree of the throttle opening TA (the side where the negative pressure of the intake pressure PM is small)
In, a set value B is provided in order to define the conventional detection range S1 by the intake pressure PM. For example, “PA-200 mmHg” can be applied as the set value B.
This conventional detection range S1 is also determined by the intake pressure PM during EGR execution.
Is included in a range higher than the intake pressure PM when the EGR is stopped. In FIG. 3, between the two set values A and B defined by the throttle opening TA, the detection limit S2 on the low opening side where the determination of the abnormality is limited in the conventional detection range S1.
Is defined. Similarly, between the two set values C and D defined by the intake pressure PM, the limit range S3 on the middle and high opening degree side where the determination of the abnormality is limited in the conventional detection range S1.
Is defined.

If the result of the determination in step 150 is affirmative, the ECU 30 determines that the operating state of the engine 1 is included in the conventional detection range S1 and proceeds to step 16.
Move to 0. If the determination result is negative, the ECU 3
0 is not included in the conventional detection range S1, but is in the detection limit range S.
The process proceeds to step 170 assuming that the process is included in either one of S2 and S3.

In step 160, the ECU 30 determines whether or not the absolute value of the currently calculated throttle change amount ΔTA is smaller than a predetermined set value F. That is, it is determined whether the operating state of the engine 1 has a predetermined change behavior. This set value F is for defining a steady state corresponding to the first stability of the present invention. This step 1
If the result of the determination in step 60 is negative, the operating state of the engine 1 corresponds to the conventional detection range S1, but does not correspond to the detection limit ranges S2 and S3, and corresponds to the first stability. Since the vehicle is not in the steady state, the ECU 30 executes the processing in step 12 to limit the abnormality determination for abnormality detection.
Return to 0. On the other hand, if the result of the determination is affirmative, the operating state of the engine 1 falls under the conventional detection range S1, but does not fall under the respective detection limit ranges S2 and S3, and falls under the first stability. The ECU 30
Shifts the processing to step 180 in order to allow abnormality determination for abnormality detection.

On the other hand, in step 170, EC
U30 determines whether or not the absolute value of the throttle change amount ΔTA calculated this time is smaller than a predetermined set value E.
The set value E is for defining a steady state corresponding to the second stability, which has a smaller change than the set value F for defining the steady state corresponding to the first stability described above. is there. That is, in this step 170, it is determined whether or not the operating state of the engine 1 has a predetermined change behavior smaller than that specified by the set value F. If the determination result in step 170 is negative, the ECU 30 determines that the operating state of the engine 1 falls within the detection limit ranges S2 and S3, but is not in the steady state corresponding to the second stability. Then, the process returns to step 120 to limit the abnormality determination for abnormality detection. On the other hand, if the determination result is affirmative, the ECU 30 determines that the operating state of the engine 1 is in the steady state corresponding to each of the detection limit ranges S2 and S3 and corresponds to the second stability. The process proceeds to step 180 in order to allow an abnormality determination for detection.

Here, the ratio of the intake pressure difference ΔP (noise: N) to the throttle change amount ΔTA and the intake pressure difference ΔP (signal: S) when EGR execution / stop is switched is defined as “S / N”. The S / N difference between the ranges S2, S1, and S3 is shown in FIGS. In each figure, the solid curve represents the intake pressure difference ΔP with respect to the throttle change amount ΔTA. The two-dot chain line represents the intake pressure difference ΔP when EGR is executed / stopped. FIG. 5 shows the S / N in the detection limit range S2 on the low opening side. As is clear from FIG. 5, in this detection limit range S2, the intake pressure difference ΔP (signal) at the time of performing / stopping the EGR indicates “about 50 mmHg”. The intake pressure difference ΔP (noise) with respect to the throttle change amount ΔTA exceeds “about 50 mmHg” when the throttle change amount ΔTA exceeds “about 4.5 deg”. Therefore, in the detection limit range S2, when the throttle change amount ΔTA is equal to or less than “about 4.5 deg”, there is S / N, that is,
Abnormality detection becomes possible, and when the throttle change amount ΔTA exceeds “about 4.5 deg”, S / N disappears, that is, abnormality detection becomes impossible. FIG. 6 shows a conventional detection range S.
1 shows the S / N. As is clear from FIG. 6, in this detection range S1, the intake pressure difference Δ
P (signal) indicates "about 75 mmHg". And
The intake pressure difference ΔP (noise) with respect to the throttle change ΔTA is such that the throttle change ΔTA is “about 12.5 de
g ", it will exceed this" about 75 mmHg ". Therefore, in this detection range S1, when the throttle change amount ΔTA is equal to or less than “about 12.5 deg”, S
/ N, and the throttle change amount ΔTA is “about 12.5d
When the value exceeds “eg”, the S / N disappears. FIG. 7 shows the S / N in the detection limit range S3 on the high opening side. As is clear from FIG. 7, in this detection limit range S3, the intake pressure difference ΔP (signal) at the time of EGR execution / stop is “about 25 mm
Hg ". Then, the intake pressure difference ΔP (noise) with respect to the throttle change amount ΔTA is represented by the throttle change amount ΔTA
Exceeds about 11 deg, this "about 25 mm
Hg ”. Therefore, in the detection limit range S3, the throttle change amount ΔTA is “about 11 deg”.
There is S / N in the following cases, and the S / N disappears when the throttle change amount ΔTA exceeds “about 11 deg”. As described above, the upper limit value of the throttle change amount ΔTA at which the S / N can be ensured differs in each of the detection ranges S1, S2, and S3. Therefore, in order to allow abnormality detection in each of the detection ranges S1, S2, and S3, it is necessary to evaluate the throttle change amount ΔTA, that is, the stability of the operating state of the engine 1, according to those ranges. The determinations in steps 160 and 170 are provided for individually evaluating the throttle change amount ΔTA that can allow abnormality detection in the conventional detection range S1 and the detection limit ranges S2 and S3. .

Then, at step 180, the ECU 30
Reads a new value of the intake pressure PM based on the detection signal of the intake pressure sensor 22 and uses the value as the intake pressure P at the time of EGR execution.
Set as 1. In step 190, the ECU 30
In order to forcibly stop EGR, EGRVSV
Turn off 34. In step 200, the ECU 30
When a predetermined time has elapsed since the GR was temporarily stopped,
Based on the detection signal of the intake pressure sensor 22, a new value of the intake pressure PM is read again, and the value is set as the intake pressure P2 when the EGR is stopped. In step 210, the ECU 30
Calculates the calculated intake pressure P11 based on the intake pressure P1 at the time of execution of EGR set this time. This calculated intake pressure P11
Is obtained by converting the intake pressure P1 at the time of EGR execution as being read at the same time as the intake pressure P2 at the time of EGR stop. The calculated intake pressure P11 is calculated by correcting the intake pressure P1 from the rate of change of the intake pressure PM.

Thereafter, at step 220, the ECU 30
Is the value of the calculated intake pressure P11 and the intake pressure P2 when the EGR is stopped.
Is calculated, and the calculation result is compared with the EGR execution time and E
The difference is set as a difference (intake pressure difference) ΔP between the intake pressure PM and the time when the GR is stopped. FIG. 4 shows the intake pressure P1 during EGR execution,
The relationship between the calculated intake pressure P11, the intake pressure P2 when EGR is stopped, and the intake pressure difference ΔP is shown. As shown by the solid curve in the figure, the calculated intake pressure P11 is compared with the intake pressure P when the EGR is stopped.
2 is relatively large, the intake pressure difference ΔP becomes E
This indicates that when the GR device 31 is normal. On the other hand, as shown by the broken curve in FIG.
When the drop of the intake pressure P2 when the EGR is stopped is relatively small with respect to 11, the intake pressure difference ΔP indicates that when the EGR device 31 is abnormal.

Thereafter, at step 230, the ECU 30
Indicates that the value of the intake pressure difference ΔP calculated this time is equal to a predetermined determination value G.
It is determined whether it is greater than. If the determination result in step 230 is affirmative, the ECU 30 proceeds to step 240
Then, a normality determination process is performed. The normality determination process is, for example,
That is, the warning lamp 16 is turned off, and a normal code indicating that the EGR device 31 is normal is stored in the backup RAM. Further, in step 250, since it is determined that the EGR device 31 is normal, the ECU 30 executes the EGR operation to restart the EGR.
The duty of the VSV 34 is controlled, and the subsequent processing ends once.

On the other hand, if the result of the determination at step 230 is negative, the ECU 30 performs an abnormality determination process at step 260. The abnormality determination process is, for example, turning on the warning lamp 16 or storing an abnormality code indicating that the EGR device 31 is abnormal in the backup RAM. Thereafter, the ECU 30 determines that the EGR device 31 is abnormal,
While R is stopped, the subsequent processing is temporarily terminated.

As described above, the EGR device 31
In the configuration described above, a part of the exhaust gas discharged from each combustion chamber of the engine 1 flows through the EGR passage 32 and the intake passage 2
And is recirculated again to each combustion chamber and provided for combustion. Here, by controlling the EGR VSV 34 and the EGR valve 33, the flow of the exhaust gas in the EGR passage 32 is adjusted, and the EGR amount introduced into the intake passage 2 is increased or decreased or stopped. By adjusting the amount of exhaust gas introduced into the intake passage 2 in this way, as shown in FIG. 3, in a specific engine operating state, the intake pressure PM is affected when the EGR is performed and when the EGR is stopped. Will change. In this abnormality detection device, this EGR execution /
EGR device 3 utilizing change in intake pressure PM at the time of stop switching
1 is detected.

That is, when the EGR VSV 34 and the EGR valve 33 are controlled in order to recirculate the exhaust gas to each combustion chamber (when the introduction of the exhaust gas into the intake passage 2 is permitted), the EGR (the intake passage 2 E30 is temporarily stopped by the ECU 30 in order to temporarily stop the introduction of exhaust gas.
The control of the GRVSV 34 and the control of the EGR valve 33 are switched. The difference between the intake pressures PM detected by the intake pressure sensor 22 before and after the switching, that is, the intake pressure difference ΔP,
An abnormality of the EGR device 31 is determined by the comparison with the predetermined determination value G by the ECU 30.

Here, the judgment by the ECU 30 is allowed only under predetermined conditions. That is, in the entire detection range S shown in FIG. 3, the range of the operating state of the engine 1 corresponding to the relatively small intake pressure difference ΔP at the time of the EGR execution / stop switching is the detection limit range for limiting the abnormality determination. S2 and S3 are specified by the set values A to D. Then, the throttle sensor 20 and the intake pressure sensor 2
Throttle opening TA and intake pressure PM detected by
Is in a steady state that does not correspond to the detection limit ranges S2 and S3 and the absolute value of the throttle change amount ΔTA corresponds to the first stability based on the set value F.
30 allows the abnormality determination of the EGR device 31. On the other hand, the detected throttle opening TA and intake pressure PM are:
Even in the case of the detection limit ranges S2 and S3, that is, even in the range where the intake pressure difference ΔP at the time of EGR execution / stop switching is relatively small, the throttle change amount Δ
The second absolute value of TA based on the set value E that has a smaller change than the first stability based on the set value F is used.
Is satisfied, the ECU 30 allows the abnormality determination. Therefore, the chances of the abnormality determination by the ECU 30 are increased as compared with the case where the abnormality determination is permitted only in the conventional detection range S1. For this reason, the intake pressure difference ΔP due to the switching between execution and stop of EGR
In the case where the abnormality of the EGR device 31 is detected by evaluating
It can be further expanded, and the treatment for abnormalities can be promoted.

Further, in this abnormality detecting device, in the abnormality determination in each of the detection limit ranges S2 and S3, the throttle change amount ΔTA is determined based on the set value E having a smaller change than the first stability based on the set value F. Abnormality determination by the ECU 30 is permitted when the second stability is satisfied. Therefore, even in the detection limit ranges S2 and S3 where the intake pressure difference ΔP becomes relatively small, the intake pressure difference ΔP at the time of EGR execution / stop switching is caused by a change in the engine operating state including a change in the throttle opening TA. It is distinguished from the intake pressure difference ΔP, that is, the S / N is secured, and the abnormality determination of the EGR device 31 is performed with accuracy. In this sense, the chance of detecting an abnormality in the EGR device 31 can be further expanded as compared with the conventional case.

According to the abnormality detecting device of this embodiment,
When the abnormality of the EGR device 31 is detected, the warning lamp 16 is turned on, so that the driver or the like can immediately recognize the abnormality. Therefore, upon receiving the notification of the abnormality, the components 32 to 35 of the EGR device 31 are appropriately inspected and checked.
By performing the repair, the EGR device 31 can be restored to a normal state. In this sense, it is possible to quickly cope with the deterioration of the emission of the engine 1 caused by the abnormality of the EGR device 31.

According to the abnormality detecting device of this embodiment, E
When an abnormality of the GR device 31 is detected, the abnormality code indicates the abnormality in the backup RAM in the ECU 30.
Is stored. Therefore, when the engine 1 is inspected, the operator can read the data in the backup RAM to check the history regarding the abnormality of the EGR device 31. In this sense, each component 32 of the EGR device 31
35 can be replaced in a timely manner, and it becomes possible to cope with deterioration of the emission of the engine 1 due to the abnormality of the EGR device 31 as soon as possible.

[Second Embodiment] Next, a second embodiment of the abnormality detecting device for an exhaust gas recirculation device for an engine according to the present invention (the invention according to the second, third, and fifth aspects) will be described. Embodiments will be described with reference to the drawings. In the following embodiments including this embodiment, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted. The explanation will focus on the points.

This embodiment is different from the first embodiment in the details of the processing of the abnormality detection control executed by the ECU 30. FIG. 8 shows a flowchart relating to abnormality detection control according to the present embodiment. In this embodiment, E
The CU 30 is an abnormality determining means according to claim 2, 3, 5,
It constitutes a first judgment permitting means, a second judgment permitting means, a stability calculating means and a judgment value calculating means.

In the flowchart of FIG. 8, the processing of each step indicated by the same number in the flowchart of FIG. 2 is the same as that of the first embodiment. In the processing content shown in the flowchart of FIG. 8, step 135 is added between step 130 and step 140, and step 221 and step 221 are added between step 220 and step 230.
The processing contents shown in the flowchart of FIG. 2 are different from those of FIG. 2 in that 22, 22, 223, 225 and 225 are added.

In this embodiment, if the result of the determination at step 130 is affirmative, at step 135, the ECU 3
0 calculates the set values E and F to be compared with the throttle change amount ΔTA based on the detected value of the throttle opening TA. The ECU 30 calculates the set values E and F by referring to the function data as shown in the graph of FIG. In this function data, each of the set values E and F increases in a quadratic curve as the throttle opening TA increases. The set value F is always larger than the set value E. After executing the processing of step 135, the ECU 30 shifts the processing to step 140 in order to calculate the throttle change amount ΔTA.

Further, after setting the intake pressure difference ΔP in step 220, in a series of processes in steps 221 to 225, the value of the judgment value G used in step 230 is calculated according to the operating state of the engine 1. This is adapted to the amount of EGR supplied to each combustion chamber per unit time, that is, the difference in EGR rate characteristics. FIG.
The R rate characteristics are shown in the graph. As is apparent from this graph, the EGR rate characteristic tends to be higher in the middle speed range and the middle load range, so that the determination value G is corrected. That is, in step 221, the ECU 30 calculates the reference intake pressure difference ΔP1 based on each value of the intake pressure PM and the engine speed NE detected this time. Next, in step 222, the ECU 30 calculates a value of the rotation speed correction coefficient kNE based on the detected value of the engine rotation speed NE. The ECU 30 calculates the value of the correction coefficient kNE by referring to function data as shown in the graph of FIG. In this function data, the correction coefficient kNE is set so as to gradually approach “1.0” in the low speed region, become “1.0” in the medium speed region, and gradually decrease from “1.0” in the high speed region. Is done. Next, step 2
At 23, the ECU 30 determines the detected throttle opening TA
The value of the opening degree correction coefficient kTA is calculated based on the value of. E
The CU 30 calculates the value of the correction coefficient kTA as shown in FIG.
Is calculated by referring to function data as shown in the graph. In this function data, the correction coefficient kTA
Gradually approaches “1.0” in the low opening range and becomes “1.0” in the middle and high opening range. Next, at step 224, E
The CU 30 calculates the value of the pressure correction coefficient kPM based on the detected value of the intake pressure PM. The ECU 30 calculates the value of the correction coefficient kPM by referring to the function data as shown in the graph of FIG. In this function data, the correction coefficient kPM is set so as to be "1.0" in the low-to-medium pressure range and to gradually decrease from "1.0" in the high-pressure range. Then, step 225
The ECU 30 calculates the calculated parameters ΔP
The determination value G is calculated according to the operating state of the engine 1 by multiplying 1, NE, kTA, and kPM by each other. After executing the process of step 225, the ECU 30 shifts the process to step 230 in order to compare the intake pressure difference ΔP with the determination value G.

As described above, the present embodiment is different from the first embodiment in the processing contents of the abnormality detection control. For this reason, according to the abnormality detection device of this embodiment, in step 135, the first stability and the second stability for determining whether the operating state of the engine 1 is in a stable steady state.
, That is, the values of the set value F and the set value E are respectively calculated according to the magnitude of the throttle opening TA, so that the set value F and the set value E adapted to the difference in the operation state of the engine 1 are determined. Will be obtained. Therefore, also in each of the above-described detection limit ranges S2 and S3, the intake pressure difference ΔP caused by the EGR execution / stop switching is smaller than the intake pressure difference ΔP caused by the change in the throttle opening TA as compared with the first embodiment. The difference is more clearly distinguished from the difference, that is, a higher S / N is obtained, and the abnormality of the EGR device 31 is more accurately determined. As a result, EG
The abnormality detection accuracy of the R device 31 can be improved, and in this sense, the opportunity for detecting the abnormality of the EGR device 31 can be expanded.

According to the abnormality detecting device of this embodiment,
The determination value G to be compared with the intake pressure difference ΔP at the time of EGR execution / stop switching is determined by various detected parameters NE, TA, PM
Thus, a determination value G suitable for the difference in the operating state of the engine 1 is obtained. Therefore, EGR
The magnitude of the intake pressure difference ΔP caused by the execution / stop switching is determined more appropriately, and the abnormality of the EGR device 31 is determined more accurately than in the first embodiment. Become. As a result, the abnormality detection accuracy of the EGR device 31 can be improved.
The opportunity for detecting an abnormality in the device 31 can be expanded. In particular, even when the operating state of the engine 1 is in a steady state and is in the conventional detection range S1 or each of the detection limit ranges S2 and S3 in which abnormality detection can be permitted, the throttle opening degree TA slightly increases or decreases. Is there. At this time, as the throttle opening TA is relatively small and the engine rotational speed NE is relatively low, the change in the intake pressure PM with respect to the change in the throttle opening TA tends to be relatively large. The above-described calculation of the determination value G enables a measure corresponding to such characteristics of the operating state.

In this embodiment, the other operations and effects are the same as those of the first embodiment.

[Third Embodiment] Next, a third embodiment of the present invention (the invention according to claims 4 and 6) embodying an abnormality detection device for an exhaust gas recirculation system of an engine. The form will be described with reference to the drawings.

This embodiment differs from the second embodiment in the details of the processing of the abnormality detection control executed by the ECU 30. FIG. 12 shows a flowchart relating to abnormality detection control according to the present embodiment. In this embodiment,
The ECU 30 constitutes abnormality determination means, first determination allowance means, second determination allowance means, stability calculation means and determination value calculation means in claims 4 and 6.

In the flowchart of FIG. 12, the processing of each step indicated by the same reference numeral in the flowchart of FIG. 8 is the same as that of the second embodiment. FIG.
8 differs from the processing shown in the flowchart of FIG. 8 in that steps 226 and 226 are added instead of step 225.

In this embodiment, in step 224,
After the pressure correction coefficient kPM is calculated, step 226 is performed.
The ECU 30 calculates the throttle change amount Δ calculated this time.
The value of the change amount correction coefficient kΔTA is calculated based on TA. The throttle change amount ΔTA includes positive and negative values, and a difference between the values indicates a slight increase or decrease in the throttle opening TA, or a tendency to increase or decrease. ECU 30
Is calculated by referring to function data as shown in the graph of FIG. In the function data, when the throttle change amount ΔTA increases as a negative value, that is, when the deceleration tendency increases, the correction coefficient kΔTA becomes larger than “1.0” in a curve. On the other hand, in the function data, when the throttle change amount ΔTA increases as a positive value, that is, when the acceleration tendency increases, the correction coefficient kΔ
TA is curvilinearly smaller than “1.0”. Thereafter, at step 227, the ECU 30 determines at step 221
.DELTA.P1, kNE, k calculated in .about.224.
The determination value G is calculated according to the operating state of the engine 1 by multiplying the change amount correction coefficient kΔTA with each other in addition to TA and kPM. The ECU 30 determines in step 227
After the execution of the process, the process proceeds to step 230 in order to compare the intake pressure difference ΔP with the determination value G.

As described above, the present embodiment differs from the second embodiment in the processing of the abnormality detection control. For this reason, according to the abnormality detection device of this embodiment, the EGR
Since the determination value G to be compared with the intake pressure difference ΔP generated by the execution / stop switching is calculated according to a small increase / decrease change in the throttle opening TA, the determination value G suitable for the small difference in the increase / decrease change is obtained. Will be obtained. Therefore, the magnitude of the intake pressure difference ΔP caused by the switching between the execution and the stop of the EGR is determined more appropriately than in the case of the first or second embodiment, and the EGR device 31 is determined.
Abnormalities are more accurately determined. As a result,
The abnormality detection accuracy of the EGR device 31 can be improved, and in this sense, the opportunity of detecting the abnormality of the EGR device 31 can be expanded.

In particular, the conventional detection range S in which the operating state of the engine 1 is in a steady state and the abnormality detection can be allowed.
Even in the case of 1 or each of the detection limit ranges S2 and S3, the throttle opening degree TA may slightly increase or decrease. At this time, when the throttle opening degree TA slightly moves in the opening direction or moves slightly in the closing direction, the intake pressure P
The change in M may be slightly different. Determination value G described above
The above calculation enables a measure to be taken in accordance with such characteristics of the operating state.

In this embodiment, the other operations and effects are the same as those of the second embodiment.

Note that the present invention is not limited to the above-described embodiment, and may be implemented by appropriately changing a part of the configuration without departing from the spirit of the invention.

(1) In the second embodiment, in order to more accurately evaluate the intake pressure difference ΔP, the throttle opening T
A, the determination value G is calculated according to the magnitude of the engine rotation speed NE and the intake pressure PM. On the other hand, the basic determination value may be corrected according to the difference in the operation state of the engine 1. The same effect as described above can also be obtained by correcting the intake pressure difference ΔP caused by the EGR execution / stop switching in accordance with the throttle opening TA, the engine speed NE, and the intake pressure PM. .

(2) In the third embodiment, in order to more accurately evaluate the intake pressure difference ΔP, the throttle opening T
The judgment value G is calculated according to the difference between the small increase and decrease of A. On the other hand, the basic determination value may be corrected according to a slight difference in increase / decrease in the throttle opening TA. Further, the same effect as described above can be obtained by correcting the intake pressure difference ΔP caused by the switching between the execution and the stop of the EGR in accordance with a small difference in the increase / decrease of the throttle opening TA.

(3) In the second and third embodiments, the set values E and F are calculated in step 135, but the processing in step 135 may be omitted.

(4) In each of the above-described embodiments, the intake pressure difference ΔP is evaluated as the difference between the intake states at the time of EGR execution / stop switching.
The difference in the amount of intake air flowing through the intake passage at the time of R execution / stop switching may be evaluated.

[0086]

According to the first aspect of the present invention,
In the abnormality detection device that detects the abnormality of the EGR device by evaluating the difference in the intake state due to the switching between the execution and the stop of the EGR, the determination by the second determination permission unit is added, and the opportunity of the determination by the abnormality determination unit is increased. Increases as compared with the case where only the first judgment permitting means permits. For this reason, the opportunity for detecting an abnormality in the EGR device can be further expanded, and the effect of promoting the treatment for the abnormality can be exhibited.

According to the configuration of the second aspect of the present invention, even in the limit range of the abnormality detection, the difference in the intake state caused by the switching between the execution and the stop of the EGR is further different from the difference in the intake state caused by the change in the operation state. The distinction will be made clearly, and the abnormality of the EGR device will be more accurately determined. Therefore, in addition to the effects of the invention described in claim 1, E
In this sense, it is possible to increase the accuracy of detecting the abnormality of the GR device, and in this sense, it is possible to increase the chance of detecting the abnormality of the EGR device.

According to the configuration of the third aspect of the invention, a judgment value suitable for the difference in the operating state of the engine is obtained,
The magnitude of the difference between the intake states caused by the switching between the GR execution and the stop will be more appropriately determined, and the abnormality of the EGR device will be more accurately determined. For this reason,
In addition to the effects of the first or second aspect of the invention, the accuracy of detecting an abnormality in the EGR device can be improved.
The effect that the opportunity of abnormality detection of a GR device can be expanded can be exhibited.

According to the configuration of the invention described in claim 4, a determination value suitable for a small difference in increase / decrease in the operating state of the engine is obtained, and the difference between the intake states caused by switching between the EGR execution and the stop is large. Is determined more appropriately, and the abnormality of the EGR device is more accurately determined. For this reason, in addition to the effect of one of the first to third aspects of the present invention, it is possible to enhance the accuracy of detecting the abnormality of the EGR device, and in this sense, it is possible to increase the chance of detecting the abnormality of the EGR device. Demonstrate.

According to the fifth aspect of the present invention, a judgment value suitable for the difference in the operating state of the engine is obtained, and
The magnitude of the difference between the intake states caused by the switching between the GR execution and the stop will be more appropriately determined, and the abnormality of the EGR device will be more accurately determined. As a result,
The effect of increasing the abnormality detection accuracy of the EGR device is exhibited.

According to the sixth aspect of the present invention, a determination value suitable for a small difference in increase / decrease in the operating state of the engine can be obtained, and the difference between the intake states caused by switching between EGR execution and stoppage can be obtained. Is determined more appropriately, and the abnormality of the EGR device is more accurately determined. As a result, the effect of increasing the abnormality detection accuracy of the EGR device is exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an engine system according to a first embodiment.

FIG. 2 is a flowchart showing an abnormality detection routine.

FIG. 3 is a graph showing a change in intake pressure with respect to a throttle opening.

FIG. 4 is also a time chart showing a relationship among an intake pressure when EGR is performed, a calculated intake pressure thereof, an intake pressure when EGR is stopped, and an intake pressure difference.

FIG. 5 is also a graph showing S / S in the detection limit range on the low opening side.
9 is a graph showing N.

FIG. 6 is also a graph showing S / N in a conventional detection range.

FIG. 7 is a graph showing the relationship between S and S in the detection limit range on the middle and high opening degree side.
4 is a graph showing / N.

FIG. 8 is a flowchart illustrating an abnormality detection routine according to the second embodiment.

FIG. 9 is also a graph showing function data of a throttle opening and a set value of a throttle change amount.

FIG. 10 is also a graph showing EGR rate characteristics.

FIGS. 11A to 11C are graphs showing function data of various operation parameters and various correction coefficients.

FIG. 12 is a flowchart illustrating an abnormality detection routine according to the third embodiment.

FIG. 13 is a graph showing function data of a throttle change amount and its correction coefficient.

FIG. 14 is a graph showing a change in intake pressure with respect to a throttle opening according to a conventional example.

[Explanation of symbols]

Reference Signs List 1 engine 2 intake passage 22 intake pressure sensor (intake state detection means) 20 throttle sensor 21 intake temperature sensor 24 rotation speed sensor 26 water temperature sensor (20, 21, 24, 26: operation state detection means) 30 ECU (abnormality determination means, (First and second determination permitting means, stable ground calculation means, determination ground calculation means) 31 EGR device 32 EGR passage (recirculation passage) 33 EGR valve 34 EGRVSV (33, 34 constitute recirculation adjustment means) ΔP Intake pressure difference (difference in intake state) G Judgment value S2 Detection limit range S3 Detection limit range E Set value (second stability reference) F Set value (first stability reference) ΔTA Throttle change amount (operation Change of state)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor ▲ Mr. Mamoru Oka 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Takeo Ogiso 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Stock In-house F term (reference) 3G062 EA05 GA02 GA04 GA06 GA08 GA12 GA17 3G084 BA05 BA20 DA28 FA02 FA10 FA11 FA20 FA29 FA33

Claims (6)

[Claims] 1. A recirculation passage for flowing a part of exhaust gas discharged from a combustion chamber of an engine to an intake passage and recirculating the exhaust gas into the combustion chamber, and adjusting a flow of the exhaust gas in the recirculation passage. A recirculation adjusting means for controlling the recirculation adjusting means to recirculate the exhaust gas to the combustion chamber through the recirculation passage and the intake passage. Operating state detecting means for detecting an operating state of the engine; intake state detecting means for detecting an intake state in the intake passage; and for recirculating the exhaust gas to the combustion chamber. When the recirculation adjusting means is controlled, the control of the recirculation adjusting means is switched to temporarily stop the recirculation of the exhaust gas, and detected before and after the switching. Abnormality detection means for determining an abnormality of the exhaust gas recirculation device by comparing the difference between the intake states to be performed with a predetermined determination value. An operating state range of the engine corresponding to a relatively small difference between the intake states is specified as a limiting range for limiting the determination by the abnormality determining means, and the detected operating state corresponds to the limiting range. And when the vehicle is in a steady state corresponding to the first degree of stability, a first judgment permitting means for permitting the judgment by the abnormality judging means, and the detected operating state falls within the limited range. In this case, when the detected operating state is in a steady state corresponding to the second stability, which has a smaller change than the first stability, the abnormality determination means determines Abnormality detection apparatus for an exhaust gas recirculation system for an engine, characterized in that a second determination permission means for permitting. 2. The abnormality detection device for an exhaust gas recirculation device for an engine according to claim 1, wherein at least one of the first stability and the second stability is the detected operating state. An abnormality detection device for an exhaust gas recirculation device of an engine, comprising a stability calculation means for calculating according to the following. 3. The abnormality detection device for an exhaust gas recirculation device for an engine according to claim 1, wherein a determination value compared with the difference between the intake states is set to the detected operation state. An abnormality detection device for an exhaust gas recirculation device of an engine, comprising: a determination value calculation means for calculating the abnormality value. 4. The abnormality detection device for an exhaust gas recirculation device of an engine according to claim 1, wherein the determination value that is compared with the difference in the intake state is detected. An abnormality detection device for an exhaust gas recirculation device of an engine, comprising: a determination value calculation means for calculating in accordance with a small increase / decrease change in an operating state. 5. A recirculation passage for flowing a part of exhaust gas discharged from a combustion chamber of an engine to an intake passage and recirculating the exhaust gas to the combustion chamber, and adjusting a flow of the exhaust gas in the recirculation passage. A recirculation adjusting means for controlling the recirculation adjusting means to recirculate the exhaust gas to the combustion chamber through the recirculation passage and the intake passage. Operating state detecting means for detecting an operating state of the engine; intake state detecting means for detecting an intake state in the intake passage; and for recirculating the exhaust gas to the combustion chamber. When the recirculation adjusting means is controlled, the control of the recirculation adjusting means is switched to temporarily stop the recirculation of the exhaust gas, and detected before and after the switching. Abnormality detection means for determining abnormality of the exhaust gas recirculation device by comparing the difference between the intake states to be performed with a predetermined determination value. An abnormality for an exhaust gas recirculation device for an engine, comprising: a determination value calculating means for calculating a determination value to be compared with the difference between the intake states according to the detected operating state. Detection device. 6. A recirculation passage for flowing a part of exhaust gas discharged from a combustion chamber of an engine to an intake passage and recirculating the exhaust gas to the combustion chamber, and adjusting a flow of the exhaust gas in the recirculation passage. A recirculation adjusting means for controlling the recirculation adjusting means to recirculate the exhaust gas to the combustion chamber through the recirculation passage and the intake passage. Operating state detecting means for detecting an operating state of the engine; intake state detecting means for detecting an intake state in the intake passage; and for recirculating the exhaust gas to the combustion chamber. When the recirculation adjusting means is controlled, the control of the recirculation adjusting means is switched to temporarily stop the recirculation of the exhaust gas, and detected before and after the switching. Abnormality detection means for determining an abnormality of the exhaust gas recirculation device by comparing the difference between the intake states to be performed with a predetermined determination value. An exhaust gas recirculation system for an engine, comprising: a determination value calculating unit configured to calculate a determination value to be compared with the difference between the intake states according to a small increase / decrease change in the detected operating state. Anomaly detection device for the device.