JP2000240472A - Failure diagnostic device for exhaust valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely perform the failure diagnosis of a valve mechanism provided on the exhaust passage of an internal combustion engine regardless of the detecting method of intake air quantity by performing the failure diagnosis of the valve mechanism on the basis of the change of the engine rotating speed when the opening of the valve mechanism is changed. SOLUTION: A three-way catalyst 14 is interposed in the middle of the exhaust pipe 13 of an internal combustion engine 1, an adsorptive mechanism 15 is provided in the upstream thereof, and an openable and closable valve mechanism is provided on the upstream opening end within the adsorptive mechanism 15. When the failure diagnosis of such a valve device is performed, a control of laying the valve device once from the full open state to the full close state and then returning it to the full open state is executed in a CPU 25 when a failure diagnosis condition for the valve device such that the warming up is completed in idling, the deposition of the unburned fuel component adsorbed to the adsorbent is completed, the control of an EGR valve 22a is in non-executing state, the vehicle speed is zero, or the like is established. The failure diagnosis of the valve device is performed on the basis of the change of fuel injection quantity and change of engine rotating speed at this time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for diagnosing a failure of a valve mechanism (exhaust valve) provided in an exhaust passage of an internal combustion engine.

[0002]

2. Description of the Related Art For an internal combustion engine mounted on an automobile or the like, there has been proposed a technique of providing a valve mechanism for various purposes in an exhaust passage in an exhaust purification system, a supercharging system, an exhaust brake system, or the like.

As a valve mechanism used in an exhaust gas purification system, for example, a bypass passage bypassing a part of an exhaust passage, and a three-way catalyst, an unburned fuel component adsorbent, a storage reduction NO _In an exhaust gas purification system provided with an exhaust gas purification mechanism such as an _X catalyst or a diesel particulate filter (DPF), an exhaust valve provided to switch the flow of exhaust gas to an exhaust passage and a bypass passage is known. I have.

The valve mechanism used in the supercharging system is, for example, a turbine housing provided in an exhaust passage of an internal combustion engine and containing a turbine wheel that rotates by the pressure of exhaust gas, and a valve mechanism provided in an intake passage of the internal combustion engine. In a turbocharger system including a compressor housing containing a compressor wheel that rotates integrally with a turbine wheel and a bypass passage communicating an exhaust passage upstream of the turbine wheel and an exhaust passage downstream of the turbine wheel, the bypass passage is opened and closed. A wastegate valve provided for the purpose is known.

[0005] As a valve mechanism used in an exhaust brake system, for example, an exhaust throttle valve provided in an exhaust passage to reduce an exhaust flow rate in an exhaust passage during braking of a vehicle is known.

Incidentally, in the various valve mechanisms as described above, there is a risk that unburned fuel components and carbon contained in the exhaust gas adhere to each other, or exhaust gas leaks due to deformation and wear of the valve element due to heat of the exhaust gas. Therefore, it is also important to accurately determine the failure of the valve mechanism.

In response to such a demand, a diagnostic device for an exhaust gas purifying device described in Japanese Patent Application Laid-Open No. 8-334014 is conventionally known. This diagnostic apparatus is configured such that a passage having a higher exhaust resistance of the exhaust passage and the bypass passage is fully closed from a fully closed state, in other words, a passage having a lower exhaust resistance of the exhaust passage and the bypass passage is fully opened from a fully opened state. The exhaust valve is operated to be closed, and a failure of the exhaust valve is diagnosed based on a change in the intake pipe pressure at that time.

That is, in the above-described diagnostic apparatus, when the exhaust valve is normal, the back pressure increases due to the opening / closing operation of the exhaust valve, whereby the intake pipe pressure changes to the atmosphere side.
This is based on the finding that when the exhaust valve is out of order, the change in the back pressure is reduced even if control is performed to open and close the exhaust valve, and the change in the intake pipe pressure is reduced accordingly.

[0009]

When the above-described diagnostic apparatus is applied to an internal combustion engine of a speed density system for estimating an intake air amount based on an intake pipe pressure and an engine speed, the diagnostic apparatus is provided in an intake passage. Since a pressure sensor is installed in advance, failure diagnosis can be performed using the output signal of the pressure sensor.However, when applied to a mass flow type internal combustion engine that directly detects the intake air amount with a sensor such as an air flow meter However, in a general mass flow type internal combustion engine, since a pressure sensor is not attached to an intake passage, there is a problem that a new pressure sensor must be attached.

Further, the intake pipe pressure is susceptible to the influence of the pulsation of the intake air and the change of the atmospheric pressure due to the change of the altitude in addition to the change of the back pressure. It is difficult to determine a change in the intake pipe pressure due to a change in the intake pipe pressure and a change in the intake pipe pressure due to a factor other than a change in the back pressure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and in an internal combustion engine having a valve mechanism in an exhaust passage, a failure diagnosis of the valve mechanism can be accurately performed regardless of a method of detecting an intake air amount. It aims to provide technology.

[0012]

The present invention employs the following means to solve the above-mentioned problems. That is, a failure diagnosis device for an exhaust valve according to the present invention includes a valve mechanism provided in an exhaust passage of an internal combustion engine, engine speed detection means for detecting an engine speed of the internal combustion engine, and an opening degree of the valve mechanism. And a failure diagnosing means for diagnosing a failure of the valve mechanism based on a change in the engine speed when the engine speed is changed.

[0013] In the fault diagnostic apparatus configured as described above,
The failure diagnosis means determines whether or not the valve mechanism has failed based on a change in the engine speed when the opening degree of the valve mechanism provided in the exhaust passage is changed to the opening direction or the closing direction.

Here, when the valve mechanism is normal, when the opening degree of the valve mechanism is changed to the closing direction or the opening direction,
The resistance of the exhaust gas in the exhaust passage changes, and accordingly, the magnitude of the back pressure acting on the internal combustion engine changes.

For example, when the back pressure increases due to a change in the opening of the valve mechanism, the operation of discharging the burned gas in the exhaust stroke is hindered, and the operation of sucking fresh air in the intake stroke is hindered. The intake air volume of the engine decreases.

On the other hand, when the back pressure is reduced by changing the opening degree of the valve mechanism, the operation of discharging the burned gas in the exhaust stroke is promoted, and the intake operation of fresh air in the intake stroke is promoted accordingly. The intake air volume of the engine increases.

When the intake air amount changes as described above, the internal combustion engine increases or decreases the fuel injection amount in accordance with the change in the intake air amount, so that the engine speed changes. Therefore,
If the engine speed changes to some extent when the opening of the valve mechanism is changed, the failure diagnosis means determines that the valve mechanism is normal, and determines the engine rotation when the opening of the valve mechanism is changed. If the amount of change in the number is smaller than normal, it can be determined that an abnormality has occurred in the valve mechanism.

Next, the failure diagnosis device for an exhaust valve according to the present invention switches a bypass passage bypassing the main exhaust passage in the exhaust passage of the internal combustion engine, and switches the flow of exhaust gas to the main exhaust passage and the bypass passage. An exhaust valve, an engine speed detecting means for detecting an engine speed of the internal combustion engine, and a failure for performing a failure diagnosis of the exhaust valve based on a change in the engine speed when the opening of the exhaust valve is changed. Diagnostic means may be provided.

As the exhaust valve mentioned here, (1) an exhaust valve capable of fully closing either the main exhaust passage or the bypass passage (when the main exhaust passage is fully opened, the bypass passage is fully closed;
(2) an exhaust valve capable of opening and closing only the main exhaust passage (when the main exhaust passage is fully opened, both the main exhaust passage and the bypass passage are conductive) And the exhaust valve is configured such that only the bypass passage is in a conductive state when the main exhaust passage is fully closed) or (3) an exhaust valve capable of opening and closing only the bypass passage (main exhaust valve when the bypass passage is fully opened) An exhaust valve configured such that both the exhaust passage and the bypass passage are in a conductive state and only the main exhaust passage is in a conductive state when the bypass passage is fully closed can be exemplified.

However, when the present invention is applied to the exhaust valve (1), it is assumed that the exhaust resistance of the main exhaust passage and the exhaust resistance of the bypass passage are different. When the exhaust valve as described above is normal, since the exhaust resistance of the exhaust passage changes due to the change in the opening of the exhaust valve, the magnitude of the back pressure acting on the internal combustion engine changes. The intake air volume changes. In an internal combustion engine, the fuel injection amount is increased or decreased according to a change in the intake air amount, and as a result, the engine speed changes.

Therefore, the failure diagnosis means determines that the exhaust valve is normal and changes the opening of the exhaust valve if the engine speed changes to some extent when the opening of the exhaust valve is changed. If the change amount of the engine speed at the time of the occurrence is smaller than the normal time, it is possible to determine that an abnormality has occurred in the exhaust valve.

The failure diagnosing means may perform the failure diagnosis of the exhaust valve using the fuel injection amount as a parameter instead of the engine speed. In this case, the failure diagnosis unit determines that the exhaust valve is normal if the fuel injection amount changes to some extent when the opening of the exhaust valve is changed, and determines that the opening of the exhaust valve is changed. If the change amount of the fuel injection amount is smaller than normal, it is determined that an abnormality has occurred in the exhaust valve.

Further, the failure diagnosis means may perform the failure diagnosis based on two parameters of the engine speed and the fuel injection amount. Further, the failure diagnosis means may perform the failure diagnosis of the exhaust valve on condition that the operation state of the internal combustion engine is in a constant load operation range. It is preferable to perform a failure diagnosis of the exhaust valve when the vehicle is in the load operation range.

This is because, when the load of the internal combustion engine changes during the failure diagnosis, the fuel injection amount and the engine speed change with the change in the load. Therefore, the failure diagnosis of the exhaust valve is executed in such a situation. This may cause an erroneous diagnosis.

The bypass passage may be provided with exhaust gas purifying means for purifying exhaust gas. An example of the exhaust gas purifying means is an adsorbent that adsorbs unburned fuel components contained in exhaust gas. In this case, the failure diagnosis unit may execute the failure diagnosis of the exhaust valve when the air-fuel ratio of the exhaust gas downstream of the adsorbent is in a lean atmosphere.

This is because an exhaust gas purifying mechanism, such as a three-way catalyst, which exhibits optimal purifying performance when the air-fuel ratio of exhaust gas is within a predetermined range (catalyst purifying window), is disposed in the exhaust passage downstream of the adsorbent. The case is taken into account.

That is, when the unburned fuel component adsorbed by the adsorbent is desorbed or the desorbed amount of the unburned fuel component increases due to the change in the opening of the exhaust valve related to the failure diagnosis, it flows into the exhaust purification mechanism. The air-fuel ratio of the exhaust gas changes to the rich side, but if the air-fuel ratio of the exhaust gas is in a lean atmosphere, the air-fuel ratio of the exhaust gas will increase even if unburned fuel components released from the adsorbent are added to the exhaust gas. It converges in the catalyst purification window without an excessive rich atmosphere.

Further, the failure diagnosis means may perform a failure diagnosis of the exhaust valve after the completion of warm-up of the internal combustion engine. This is because the combustion state of the internal combustion engine before the completion of warm-up is likely to be unstable, and the operating state of the internal combustion engine may be unstable due to a change in the opening of the exhaust valve related to the failure diagnosis.

When the adsorbent is disposed in the bypass passage, the failure diagnosis means performs the failure diagnosis of the exhaust valve after the desorption of the unburned fuel component adsorbed by the adsorbent is completed. You may. This is because if the opening degree of the exhaust valve related to the failure diagnosis is changed before the completion of the desorption of the unburned fuel component,
Inadvertent desorption of unburned fuel components adsorbed by the adsorbent,
Alternatively, the amount of unburned fuel component desorbed may be increased, and the exhaust emission may be deteriorated.

[0030]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the exhaust valve failure device according to the present invention. Here, the unburned fuel component (for example, unburned H
The case where the present invention is applied to an exhaust gas purification system provided with an adsorbent for adsorbing C) will be described as an example.

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine provided with an exhaust gas purification system to which the present invention is applied. The internal combustion engine 1 shown in FIG. 1 is a four-cycle four-cylinder internal combustion engine, which is a mass flow type internal combustion engine that directly detects an intake air amount by an air flow meter.

An intake branch pipe 2 is connected to the internal combustion engine 1.
Each branch pipe of the intake branch pipe 2 communicates with a combustion chamber of each cylinder via an intake port (not shown). The intake branch pipe 2
Is connected to the surge tank 3 and this surge tank 3
Are connected to an air cleaner box 5 via an intake pipe 4.

The intake pipe 4 is provided with a throttle valve 6 for adjusting the flow rate of intake air flowing through the intake pipe 4 in conjunction with an accelerator pedal (not shown).
Is provided with a throttle position sensor 7 for outputting an electric signal corresponding to the opening degree of the throttle valve 6. An air flow meter 8 that outputs an electric signal corresponding to the mass of intake air flowing through the intake pipe 4 is attached to the intake pipe 4.

The fuel injection valves 10a, 10b, 10c, and 10d (hereinafter referred to as fuel injection valves 1)
0), and these fuel injection valves 1
Numeral 0 is connected to the fuel distribution pipe 9. The fuel distribution pipe 9 distributes fuel pumped from a fuel pump (not shown) to the fuel injection valves 10.

Each of the fuel injection valves 10 has a drive circuit 11
a, 11b, 11c and 11d (hereinafter collectively referred to as a drive circuit 11) are attached, and when a drive current from these drive circuits 11 is applied to the fuel injection valve 10, the fuel injection valve 1
0 is opened, and the fuel supplied from the fuel distribution pipe 9 is injected toward the intake port of each cylinder.

On the other hand, an exhaust branch pipe 12 is connected to the internal combustion engine 1, and each branch pipe of the exhaust branch pipe 12 communicates with a combustion chamber of each cylinder via an exhaust port (not shown). The exhaust branch pipe 12 is connected to an exhaust pipe 13 and the exhaust pipe 13
Is connected downstream to a muffler (not shown).

An exhaust recirculation pipe 22 for guiding a part of the exhaust gas flowing through the exhaust branch pipe 12 to the intake system of the internal combustion engine 1 is connected to the exhaust branch pipe 12. It is connected to the. In the middle of the exhaust gas recirculation pipe 22, a flow rate adjusting valve (EGR valve) 22a for adjusting the flow rate of the exhaust gas flowing in the exhaust gas recirculation pipe 22 is provided.

In the middle of the exhaust pipe 13, a three-way catalyst 14 is provided.
Is provided. The three-way catalyst 14 is composed of a ceramic carrier made of cordierite formed in a lattice shape so as to have a plurality of through holes along the flow direction of exhaust gas, and a catalyst layer coated on the surface of the ceramic carrier.

The catalyst layer is formed, for example, by supporting a platinum-rhodium (Pt-Rh) -based noble metal catalyst material on the surface of porous alumina (Al ₂ O ₃ ) having a large number of pores. .

The three-way catalyst 14 configured as described above is activated when the temperature is equal to or higher than a predetermined temperature. When the air-fuel ratio of the inflowing exhaust gas is within a predetermined range (catalyst purification window) near the stoichiometric air-fuel ratio, the three-way catalyst 14 is activated. Hydrocarbon (HC) and carbon monoxide (CO) contained therein are reacted with oxygen (O ₂ ) in exhaust gas to form water (H
₂ O) and carbon dioxide (CO ₂ ), while simultaneously removing nitrogen oxides (NO _x ) in the exhaust hydrocarbons (H
C) and carbon monoxide (CO) to react with water (H
₂ O), carbon dioxide (CO ₂ ), and nitrogen (N ₂ ).

An upstream air-fuel ratio sensor 18 for outputting an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing into the three-way catalyst 14 is attached to the exhaust pipe 13 upstream of the three-way catalyst 14. A downstream air-fuel ratio sensor 19 that outputs an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing out of the three-way catalyst 14 is attached to the exhaust pipe 13 downstream of 14.

The upstream air-fuel ratio sensor 18 and the downstream air-fuel ratio sensor 19 are, for example, zirconia (Zr
O ₂ ) is formed of a solid electrolyte portion fired into a cylindrical shape, an outer platinum electrode covering the outer surface of the solid electrolyte portion, and an inner platinum electrode covering the inner surface of the solid electrolyte portion, and a voltage is applied between the electrodes. In this case, the sensor outputs a current having a value proportional to the oxygen concentration in the exhaust gas (the concentration of the unburned fuel component when the ratio is richer than the stoichiometric air-fuel ratio) as the oxygen ions move.

An adsorption mechanism 15 is provided in the exhaust pipe 13 upstream of the three-way catalyst 14. This suction mechanism 15
As shown in FIG. 2, the outer cylinder 150 has an inner diameter larger than the outer diameter of the exhaust pipe 13, and the outer cylinder 150 has an inner diameter larger than the outer diameter of the exhaust pipe 13 and has an outer diameter smaller than the inner diameter of the outer pipe 150. The cylinder 151, the middle cylinder 151, and the outer cylinder 1
50, and an annular adsorbent 152 disposed between them.

The exhaust pipe 13 is isolated in the outer cylinder 150 into an upstream exhaust pipe 13a and a downstream exhaust pipe 13b. The upstream exhaust pipe 13a and the downstream exhaust pipe 13
b is connected via the outer cylinder 150.

At this time, the downstream exhaust pipe 13b is held in the outer cylinder 150 so that the opening end on the upstream side protrudes into the outer cylinder 150, and the tip end thereof is a non-fixed end.
Correspondingly, the middle cylinder 151 has one end of the middle cylinder 151 connected to the outer cylinder 150, the exhaust pipe 13, or the valve device 16 described later.
0, and the other end is not fixed to any of the outer cylinder 150, the exhaust pipe 13, and the valve device 160, and
It is assumed that the upstream end of the middle cylinder 151 is held in the outer cylinder 150 so as to extend upstream from the upstream end of the downstream exhaust pipe 13b.

This is because the outer cylinder 150 is connected to the upstream exhaust pipe 13a.
And the downstream exhaust pipe 13b, and the temperature is lower than that of the middle cylinder 151 and the downstream exhaust pipe 13b.
1 and the upstream end of the downstream exhaust pipe 13b is fixed directly or indirectly via the valve device 160 to the outer cylinder 150, the outer cylinder 150, the middle cylinder 151, and the downstream exhaust pipe 13b. This is because there is a possibility that the main suction mechanism 15 may be damaged due to the difference in thermal expansion, and the durability is reduced.

On the other hand, the adsorbent 152 is fixed to only one of the outer cylinder 150 and the middle cylinder 151, and can allow a difference in thermal expansion between the outer cylinder 150 and the middle cylinder 151 due to a temperature difference. It has become.

The middle cylinder 151 and the downstream exhaust pipe 13b
And the downstream exhaust pipe 13
The holding member 153 is arranged to improve the earthquake resistance of the b.

The holding member 153 is fixed to only one of the inner wall of the middle cylinder 151 and the outer wall of the downstream exhaust pipe 13b so that the middle cylinder 151 and the downstream exhaust pipe 13b are not fixed to each other. Thus, the difference between the thermal expansion of the downstream exhaust pipe 13b in the axial direction and the thermal expansion of the middle cylinder 151 in the axial direction can be absorbed.

Next, a valve device 160 for opening and closing the open end is provided at the upstream open end of the middle cylinder 151. The valve device 160 realizes the exhaust valve according to the present invention, and is configured by a butterfly type two-way valve as shown in FIG. Specifically, the valve device 160 includes a housing 161 fitted to the upstream opening end of the middle cylinder 151.
And a passage 16 passing through the housing 161 in the axial direction.
4, a valve body 162 for opening and closing the passage 164, and a shaft 163 attached to the valve body 162.

One end of the shaft 163 is rotatably supported by the housing 161.
Is connected to a bearing 1 provided on an outer wall of the outer cylinder 150.
65 rotatably supported.

The other end of the shaft 163 is connected to an actuator 166 via a link mechanism or the like. The actuator 166 includes a stepper motor or the like, and can open and close the shaft 163 and the valve body 162 according to the magnitude of the applied current.

In the suction mechanism 15 configured as described above,
When the three-way catalyst 14 is in the inactive state, the actuator 166 is controlled so that the valve element 162 of the valve device 160 is fully closed as shown in FIG. At this time, the downstream side exhaust pipe 13b is connected from the upstream side exhaust pipe 13a through the passage 164.
The exhaust passage (main exhaust passage) communicating with the exhaust pipe 13 is in a non-conductive state, and the space 154 and the space 155 are connected from the upstream exhaust pipe 13a.
The exhaust passage (bypass passage) that communicates with the downstream exhaust pipe 13b via the air passage becomes a conductive state.

As a result, all of the exhaust gas from the upstream exhaust pipe 13a is led to the annular space 154 formed between the middle tube 151 and the outer tube 150, and is led to the adsorbent 152.
After passing through the adsorbent 152, the exhaust gas guided to the adsorbent 152 collides with the inner wall of the outer cylinder 150 to change the flow direction, and the annular exhaust formed between the middle cylinder 151 and the downstream exhaust pipe 13b. Guided to space 155. The exhaust gas guided to the space 155 flows from the downstream side to the upstream side of the adsorption mechanism 15 in the space 155, collides with the valve device 160, changes the flow direction, and flows into the downstream side exhaust pipe 13b.

After the three-way catalyst 14 has been activated, FIG.
The actuator 166 is controlled such that the valve body 162 of the valve device 160 is fully closed as shown in FIG. At this time, in the outer cylinder 150, the passage 1
The main exhaust passage communicating with the downstream exhaust pipe 13b via the second exhaust gas passage 64 becomes conductive, and the bypass passage communicating from the upstream exhaust pipe 13a to the downstream exhaust pipe 13b via the space 154 and the space 155 is electrically connected. Become.

Note that the suction mechanism 15 shown in the present embodiment is
It is assumed that the exhaust resistance of the bypass passage is larger than the exhaust resistance of the main exhaust passage. For example, the cross-sectional area of the adsorbent 152 as shown in FIG. _{5 (= D 3 · π /} 4-D 2 ·
(π / 4) is smaller than the cross-sectional area of the main exhaust passage (= D ₁ · π / 4), preferably (cross-sectional area of adsorbent 152) / (cross-sectional area of main exhaust passage) ≦ 0.5. The suction mechanism 15 may be configured so as to be as follows.

As a method for making the exhaust resistance of the bypass passage larger than the exhaust resistance of the main exhaust passage, as shown in FIG. 6, the cross-sectional area of the entrance portion of the bypass passage (= π · D ₁₎
L ₁ ) is preferably smaller than the cross-sectional area of the main exhaust passage (= D ₁ · π / 4), preferably (the cross-sectional area of the entrance of the bypass passage) / (the cross-sectional area of the main exhaust passage) ≦ 0. 5, the suction mechanism 15 may be configured.

As a method of making the exhaust resistance of the bypass passage larger than the exhaust resistance of the main exhaust passage, as shown in FIG. 7, the cross-sectional area of the outlet of the bypass passage (= π · D ₁₎
L ₂ ) is preferably smaller than the cross-sectional area of the main exhaust passage (= D ₁ · π / 4), preferably (cross-sectional area of the outlet of the bypass passage) / (cross-sectional area of the main exhaust passage) ≦ 0. 5, the suction mechanism 15 may be configured.

Further, as a method of making the exhaust resistance of the bypass passage larger than the exhaust resistance of the main exhaust passage, the adsorbent 1
A method for adjusting the number of cells constituting the member 52, for example, the number of cells, the wall thickness, the length, the coating amount of the adsorbent, and the like of the honeycomb body can also be exemplified.

Returning to FIG. 1, the crankshaft (not shown) of the internal combustion engine 1 has a predetermined angle (for example, 30 degrees).
A crank position sensor 20 that outputs a pulse signal each time the motor rotates and a water temperature sensor 21 that outputs an electric signal corresponding to the temperature of cooling water flowing in a water jacket formed inside the internal combustion engine 1 are attached. I have.

The internal combustion engine 1 is provided with an electronic control unit (ECU) 23 for controlling the engine. The ECU 23 includes a crank position sensor 20, a water temperature sensor 21, a throttle position sensor 7, an air flow meter 8, an upstream air-fuel ratio sensor 18, and a downstream air-fuel ratio sensor 19. Vehicle speed sensors 32 that output an electric signal corresponding to the traveling speed are connected via electric wiring, and output signals of the sensors are input to the ECU 23.

The ECU 23 determines the operating state of the internal combustion engine 1 using the output signals from the sensors as parameters, and controls the fuel injection control, ignition control, control of the EGR valve 22a, or Valve device 160
It performs various controls such as opening and closing control.

Here, as shown in FIG. 8, the ECU 23 has a CPU connected to each other by a bidirectional bus 24.
25, ROM 26, RAM 27, and backup RAM 2
8, an input port 29 and an output port 30, and an A / D converter (A / D) 31 connected to the input port 29.

The A / D converter 31 includes a throttle position sensor 7, an air flow meter 8, an upstream air-fuel ratio sensor 18, a downstream air-fuel ratio sensor 19, and a water temperature sensor 2.
1, and connected to the vehicle speed sensor 32 via electric wiring,
The output signals of these sensors are converted from the analog signal format to the digital signal format, and the converted output signals are input to the input port 29.

The input port 29 is connected to the crank position sensor 20 via electric wiring, and transmits an output signal from the crank position sensor 20 and the like to the CPU 25 and the RAM 27 via the bidirectional bus 24. Further, the input port 29 is connected to the throttle position sensor 7, the air flow meter 8, the upstream air-fuel ratio sensor 18, the downstream air-fuel ratio sensor 1 input from the A / D converter.
9 or the output signal of the water temperature sensor 21
4 to the CPU 25 and the RAM 27.

The output port 30 is connected to the drive circuit 11, the actuator 166, and the EGR valve 22a via electric wiring, and transmits various control signals output from the CPU 25 to the drive circuit 11, the actuator 166,
And to the EGR valve 22a.

The ROM 26 includes a fuel injection amount control routine for determining the amount of fuel to be injected from each fuel injection valve 10, an air-fuel ratio feedback control routine for performing air-fuel ratio feedback control of the fuel injection amount, and a fuel injection valve. 1
A fuel injection timing control routine for determining a zero fuel injection timing, an EGR control routine for controlling the EGR valve 22a, a flow path switching control routine for controlling the valve device 160, and a failure diagnosis of the valve device 160 are performed. Application programs, such as a valve device failure diagnosis control routine, and various control maps.

The control map includes, for example, a fuel injection amount control map showing the relationship between the operating state of the internal combustion engine 1 and the fuel injection amount, and a fuel injection timing control showing the relationship between the operating state of the internal combustion engine 1 and the fuel injection timing. A map, an EGR valve opening control map showing the relationship between the operating state of the internal combustion engine 1 and the opening of the EGR valve 22a, the temperature of the cooling water at the time of starting the internal combustion engine 1 and the time from when the three-way catalyst 14 is activated And an activity determination control map or the like showing a relationship with the time (hereinafter, referred to as a catalyst activation time) required for the reaction.

The RAM 27 stores an output signal from each sensor, a calculation result of the CPU 25, and the like. The calculation result is, for example, an engine speed or the like calculated based on a time interval at which the crank position sensor 20 outputs a pulse signal. And output signals from each sensor and CPU
The calculation result of 25 is rewritten to the latest data every time the crank position sensor 20 outputs a signal.

The backup RAM 28 is a nonvolatile memory capable of storing data even after the operation of the internal combustion engine 1 is stopped, and stores, for example, failure information of the valve device 160 and the like. The CPU 25 operates according to an application program stored in the ROM 26 and
The fuel injection control, the control of the EGR valve 22a, the valve device 16
0 and the failure diagnosis control of the valve device 160, which is the gist of the present invention.

For example, in the fuel injection control, the CPU 25
Determines the fuel injection amount and the fuel injection timing according to the fuel injection amount control routine, the air-fuel ratio feedback control routine, and the fuel injection timing control routine of the ROM 26, and determines the drive circuit 1 according to the determined fuel injection amount and the fuel injection timing.
1 (fuel injection valve 10) is controlled.

When determining the fuel injection amount, the CPU 25
Determines the fuel injection amount (TAU) according to the following equation: TAU = TP * FWL * (FAF + FG) * [FASE + FAE + FOTP + FDE (D)] * FFC + TAU
V (TP: basic injection amount, FWL: warm-up increase, FAF: air-fuel ratio feedback correction coefficient, FG: air-fuel ratio learning coefficient, FASE: increase after start, FAE: acceleration increase, FOTP: OTP increase, FDE (D): Deceleration increase (decrease), FFC: Fuel cut return correction coefficient, T
(AUV: invalid injection time) At that time, the CPU 25 determines the operating state of the internal combustion engine using the output signal values of various sensors as parameters, and based on the determined engine operating state and the fuel injection amount control map in the ROM 26, Basic injection amount (TP), warm-up increase (F
WL), increase after startup (FASE), acceleration increase (FA
E), OTP increase (FOTP), deceleration increase (FDE)
(D)), the correction coefficient at fuel cut return (FF
C), and calculates an invalid injection time (TAUV) and the like.

On the other hand, the CPU 25 calculates an air-fuel ratio feedback correction coefficient (FAF) according to an air-fuel ratio feedback control routine. In the air-fuel ratio feedback control routine, the CPU 25 first determines whether an air-fuel ratio feedback control condition is satisfied.

The above-described air-fuel ratio feedback control conditions include, for example, that the coolant temperature is equal to or higher than a predetermined temperature, that the internal combustion engine 1 is in a non-start state, that the fuel injection amount is not increased after start-up correction. The fuel injection amount warm-up increase correction is not executed, the fuel injection amount acceleration increase correction is not executed, and the OTP increase correction for preventing heating of exhaust system components such as the three-way catalyst 14 is not executed. Conditions such as a state, a state in which the fuel cut control is not executed, and the like can be exemplified.

If the air-fuel ratio feedback control condition is not satisfied, the CPU 25 sets the air-fuel ratio feedback correction coefficient (FAF) to "1.0" and ends the execution of the air-fuel ratio feedback control routine.

When the above-described air-fuel ratio feedback control condition is satisfied, the CPU 25 inputs the output signal value of the upstream air-fuel ratio sensor 18 via the A / D converter 31 and the input port 29 and outputs the input output value. Based on the signal value and the response delay time of the upstream air-fuel ratio sensor 18, it is determined whether the actual air-fuel ratio of the exhaust gas is leaner or richer than the stoichiometric air-fuel ratio.

When the CPU 25 determines that the actual exhaust air-fuel ratio is richer than the stoichiometric air-fuel ratio, the fuel injection amount (T
AU), the value of the air-fuel ratio feedback correction coefficient (FAF) is corrected so that the actual exhaust air-fuel ratio is leaner than the stoichiometric air-fuel ratio.
The value of the air-fuel ratio feedback correction coefficient (FAF) is corrected to increase the amount of U).

Subsequently, the CPU 25 performs upper limit guard processing and lower limit guard processing on the air-fuel ratio feedback correction coefficient (FAF) calculated in the above-described procedure, and stores the air-fuel ratio feedback correction coefficient (FAF) after the guard processing in the RAM 27.
And temporarily terminates the execution of this routine.

The CPU 25 outputs the output of the downstream air-fuel ratio sensor 19 in parallel with the air-fuel ratio feedback control (first air-fuel ratio feedback control) based on the output signal of the upstream air-fuel ratio sensor 18 as described above. Air-fuel ratio feedback control (second air-fuel ratio feedback control) based on the signal may be executed.

In the second air-fuel ratio feedback control, C
The PU 25 compares the output signal value of the downstream air-fuel ratio sensor 19 with a predetermined reference voltage to determine whether the air-fuel ratio of the exhaust flowing out of the three-way catalyst 14 is lean or rich, and A lean / rich reference value in the first air-fuel ratio feedback control based on the determination result;
The correction amount and the like of the air-fuel ratio feedback correction coefficient (FAF) are corrected, and the output characteristics of the upstream air-fuel ratio sensor 18 vary due to individual differences, and the upstream air-fuel ratio sensor 1 changes over time.
8 suppresses deterioration of exhaust emission characteristics caused by changes in output characteristics and the like.

Next, when controlling the valve device 160, the CPU 25 sets the water temperature sensor 21
The catalyst activation time is calculated from the output signal and the activation determination control map of the ROM 26.

The CPU 25 closes the valve body 162 of the valve device 160 (main exhaust gas in the adsorption mechanism 15) until the catalyst activation time elapses, that is, while the three-way catalyst 14 is in an inactive state. A control signal is output to the actuator 166 to make the passage non-conductive.

At this time, all of the exhaust gas discharged from the internal combustion engine 1 is supplied to the bypass passage in the adsorbing mechanism 15 and the adsorbent 1.
It will flow into the three-way catalyst 14 via 52. As a result, the unburned fuel component contained in the exhaust gas is adsorbed by the adsorbent 152 without being released to the atmosphere.

After the catalyst activation time has elapsed, that is, after the three-way catalyst 14 has been activated, the CPU 25
A control signal is output to the actuator 166 so that the 60 valve bodies 162 are fully opened (the main exhaust passage in the suction mechanism 15 is in a conductive state).

At this time, since both the main exhaust passage and the bypass passage are in a conductive state in the adsorption mechanism 15, the exhaust gas discharged from the internal combustion engine 1 passes through both the main exhaust passage and the bypass passage to be three-way. The catalyst flows into the catalyst 14 and is purified by the active three-way catalyst 14.

In the suction mechanism 15 shown in the present embodiment, the exhaust inflow portion and the exhaust outflow portion of the bypass passage are arranged at close positions, so that the exhaust pressure near the exhaust inflow portion and the exhaust outflow portion The difference between the pulsation of the exhaust gas flowing through the main exhaust passage near the exhaust inflow portion and the pulsation of the exhaust gas flowing through the main exhaust passage near the exhaust outflow portion becomes small, and the internal combustion engine becomes smaller. Only a very small amount of the exhaust gas discharged from 1 flows into the three-way catalyst 14 through the bypass passage, and most of the other exhaust gas flows into the three-way catalyst 14 through the main exhaust passage. Become.

As described above, when the flow rate in the bypass passage becomes extremely small, the amount of exhaust gas passing through the adsorbent 152 becomes extremely small accordingly, so that the rate of temperature rise of the adsorbent 152 becomes gentle and the adsorbent 152 The adsorbed unburned fuel component gradually desorbs little by little, and the amount of unburned fuel component introduced from the bypass passage into the exhaust pipe 13 upstream of the three-way catalyst 14 becomes extremely small. An excessively rich state in which the air-fuel ratio of the exhaust gas flowing into the exhaust gas deviates from the catalyst purification window does not occur.

[0088] Thus, the air-fuel ratio of the exhaust gas flowing into the three way catalyst 14, the three-way catalyst 14 HC, CO, without departing from the scope of purifying catalyst capable purification window of the NO _X, the unburned fuel components (Unburned HC), and CO and NO in exhaust gas
_X is surely purified by the three-way catalyst 14, and the exhaust emission does not deteriorate.

Further, since the air-fuel ratio of the exhaust gas flowing into the three-way catalyst 14 does not excessively change (change to an excessive rich state), the upstream and downstream air-fuel ratio sensors 19 and 2
The detection accuracy of 0 does not decrease, and the air-fuel ratio feedback control described above can be executed with high accuracy.

Next, the failure diagnosis control of the valve device 160, which is the gist of the present invention, will be described. In the present embodiment, the CP
U25 controls opening and closing of the valve device 160, and
The failure diagnosis of the valve device 160 is performed based on the amount of change in the engine operation state caused by the opening / closing operation of 0.

It should be noted that at the time of failure diagnosis of the valve device 160, the valve device 1
If the engine operating state changes due to a factor other than the operation at 60, C
In the present embodiment, the failure diagnosis is performed at a time when the operating state of the internal combustion engine 1 is stable because there is a possibility that the PU 25 may make an erroneous diagnosis.

The operating state of the internal combustion engine 1 is exemplified by a steady operation in which the engine load is constant below a predetermined load, preferably an idle operation in which the engine load is low and constant. Can be.

When the internal combustion engine 1 is idling, the valve device 16
When performing the failure diagnosis of 0, the CPU 25 executes a first failure diagnosis control routine as shown in FIG. In the first failure diagnosis control routine, the CPU 25 first executes S90
At 1, it is determined whether the failure diagnosis condition of the valve device 160 is satisfied.

As the failure diagnosis conditions, for example,
(1) Warm up of the internal combustion engine 1 is completed, (2) Desorption of unburned fuel components adsorbed by the adsorbent 152 is completed, (3) Control of the EGR valve 22a is not executed (E.g., the EGR valve 22a is fully closed), (4) the internal combustion engine 1 is in the idling operation range, (5) the output signal value (vehicle speed) of the vehicle speed sensor 32 is "0", and the like. can do.

In the condition (1) described above, before the internal combustion engine 1 is completely warmed up, the engine operating state is unstable and easily fluctuates. Therefore, it is erroneously determined that the failure diagnosis is performed in such a situation. This is based on the finding that there is a risk.

As a method of determining the completion of the warm-up of the internal combustion engine 1, for example, a method of estimating from the output signal value (cooling water temperature) of the water temperature sensor 21 can be exemplified. If the valve device 160 is operated before the desorption of the unburned fuel component adsorbed on the adsorbent 152 is completed, the condition of the above (2) is that the amount of the unburned fuel component desorbed from the adsorbent 152 is reduced. increased rapidly, off the air-fuel ratio of the catalyst purification window range of the exhaust gas flowing into the three way catalyst 14, HC in the exhaust gas at the three-way catalyst 14, CO, finding that there is a risk that not be sufficiently purify NO _X It is based on.

As a method of determining the completion of the desorption of the unburned fuel component adsorbed on the adsorbent 152, for example, from the start of the internal combustion engine 1 until the valve device 160 is closed (the internal combustion engine 1). The amount of unburned fuel component adsorbed on the adsorbent 152 and the amount of unburned fuel from the integrated value of the intake air amount and the integrated value of the fuel injection amount (from the start of the three-way catalyst 14 until the catalyst activation time of the three-way catalyst 14 elapses) The time required for the desorption of the component amount (unburned fuel component desorption time) is estimated, and when the elapsed time from the time when the valve device 160 is closed reaches the unburned fuel component desorption time or more. A method for determining that the desorption of the unburned fuel component has been completed can be exemplified.

The condition of the above (3) is that the EGR valve 22a
When the control is executed, that is, when the EGR valve 22a is in the open state, the amount of intake air fluctuates due to the recirculation of exhaust gas. It is based on

In the conditions (4) and (5), the load on the internal combustion engine 1 is low and the change in the engine operating state due to factors other than the operation of the valve device 160 is extremely small in the idling operation region when the vehicle is stopped. It is based on the knowledge that.

Here, returning to the first failure determination control routine of FIG. 9, if it is determined in S901 that the failure diagnosis condition described above is not satisfied, the CPU 25 proceeds to S901 until the failure diagnosis condition is satisfied. Is repeatedly executed.

If it is determined in S901 that the failure diagnosis condition is satisfied, the CPU 25 proceeds to S90.
Proceed to 2 to start collecting data serving as parameters indicating the engine operating state.

The above-mentioned data includes, for example, the mass of air sucked into the internal combustion engine 1 during the intake stroke of one cycle: G
A (= value obtained by dividing the output signal value of the air flow meter 8 by the engine speed), fuel injection amount: TAU, engine speed: NE (based on the time interval at which the crank position sensor 20 outputs a pulse signal) Output signal value of the throttle position sensor 7 (throttle opening): TA, output signal value of the vehicle speed sensor 32 (vehicle speed): S
Loads of auxiliary equipment such as PDs and compressors for air conditioners: LOAD and the like can be exemplified.

Next, the CPU 25 proceeds to S903, and executes control to return the valve device 160 from the fully opened state to the fully closed state and then to the fully opened state. In S904, the CPU 25
Terminates the data collection process started in S902.

In step S905, the CPU 25 executes the processing in step S90.
2 to S904, whether the operating state of the internal combustion engine 1 during the control to return the valve device 160 from the fully open state to the fully closed state and then back to the fully open state has been stabilized. It is determined whether or not.

Specifically, the CPU 25 refers to the collected data, and the fully closed state of the EGR valve 22a continues (the EGR control continues and is in the non-execution state). If the idling operation state is continued, the throttle opening is continuously “0”, and the load on the accessories is constant, it is determined that the operation state of the internal combustion engine 1 is stable.

If it is determined in S905 that the operation state of the internal combustion engine 1 during the control to return the valve device 160 from the fully open state to the fully closed state and then to the fully opened state is not stable, the CPU 25 , Proceed to S906,
The data collected from S902 to S904 is deleted, and then the processes from S901 onward are executed again.

On the other hand, in S905, the valve device 160
If it is determined that the operation state of the internal combustion engine 1 during the control to return from the fully open state to the fully closed state and then to the fully open state is stable, the CPU 25 proceeds to S907,
Based on the data collected from S902 to S904, the amount of change in engine speed when the valve device 160 is controlled from the fully open state to the fully closed state: ΔNE and the amount of change in fuel injection amount: ΔTAU is calculated, and the change amount of the engine speed: ΔNE is a predetermined reference engine speed change amount: C
HEKNE or more and the amount of change in the fuel injection amount:
ΔTAU is a predetermined reference fuel injection change amount: CHEKTAU
It is determined whether or not this is the case.

Here, since the exhaust resistance of the bypass passage in the suction mechanism 15 is larger than the exhaust resistance of the main exhaust passage,
When the valve device 160 is normal, the pressure in the exhaust passage increases due to the valve body 162 operating from the fully open state to the fully closed state, and this pressure acts on the internal combustion engine 1 as back pressure. At this time, the back pressure acts as a resistance to the operation of discharging the burned gas from the cylinder during the exhaust stroke, thereby hindering the operation of sucking fresh air in the next intake stroke, and reducing the intake air amount of the internal combustion engine 1.

In the mass flow type internal combustion engine 1, the CP
U25 calculates the basic injection amount: TP required to bring the air-fuel mixture to the desired target air-fuel ratio based on the relational expression of air-fuel ratio = air mass / fuel mass and air mass: GA. The mass of air: G
When A decreases, the basic injection amount: TP is correspondingly reduced, and as a result, the fuel injection amount: TAU is reduced and the engine speed: NE is reduced.

That is, when the valve device 160 is normal, the back pressure increases due to the operation of the valve body 162 as shown in FIG.
The intake air mass: GA is reduced, and the fuel injection amount: TAU is reduced by a predetermined amount or more. As a result, the engine speed NE decreases by a predetermined speed or more.

Therefore, in the present embodiment, based on the above-described knowledge, the amount of change in the fuel injection amount when the valve device 160 is controlled from the fully open state to the fully closed state: ΔTAU and the engine speed A change amount: △ NE is calculated, and a change amount of the fuel injection amount: △ TAU is a reference fuel injection change amount: CHEKTAU.
When the engine speed change amount △ NE is equal to or greater than the reference engine speed change amount: CHEKNE, the valve device 1
60 is determined to be normal, and the amount of change in the fuel injection amount: ΔT
If AU is less than the reference fuel injection change amount: CHEKTAU and / or the engine speed change amount △ NE is less than the reference engine speed change amount: CHEKNE, it is determined that an abnormality has occurred in the valve device 160.

When the internal combustion engine 1 is provided with a variable valve timing mechanism for varying the opening / closing timing of the intake valve and / or the exhaust valve, the valve overlap amount between the intake valve and the exhaust valve when performing a failure diagnosis. May be increased to increase the degree of influence of the change in the back pressure on the intake system.

Here, returning to the first failure diagnosis control routine of FIG. 9, when the control for changing the valve device 160 from the fully open state to the fully closed state in S907 is performed, the change amount of the engine speed: △ NE is obtained. If it is determined that the reference engine speed change amount: CHEKNE or more and the fuel injection amount change amount: ΔTAU is equal to or greater than the reference fuel change amount: CHEKTAU, CP
U25 proceeds to S908, deems that the valve device 160 is normal, and ends the execution of this routine.

On the other hand, at S907, the valve device 160
Of the engine speed when the control for changing the engine from the fully open state to the fully closed state is performed: が NE is the reference engine speed change amount: CH
Less than EKNE and / or variation in fuel injection amount: $ TA
If it is determined that U is less than the reference fuel change amount: CHEKTAU, the CPU 25 proceeds to S909, and proceeds to S909.
It is considered that an abnormality has occurred in 60.

Subsequently, the CPU 25 proceeds to S910,
After performing processing for outputting warning information indicating that an abnormality has occurred in the valve device 160, such as turning on an indicator lamp provided in the vehicle interior, the execution of this routine is terminated.

Next, when the failure diagnosis of the valve device 160 is performed when the operation state of the internal combustion engine 1 is in the non-idle operation region and the engine load is constant at a predetermined load or less, C
The PU 25 executes a second failure diagnosis control routine as shown in FIG.

In the second failure diagnosis control routine, the CPU
In step S1101, it is determined whether a failure diagnosis condition for the valve device 160 is satisfied. S110
If it is determined in step 1 that the failure diagnosis condition is not satisfied, the CPU 25 repeatedly executes the process of S1101 until the failure diagnosis condition is satisfied.

If it is determined in S1101 that the failure diagnosis condition is satisfied, the CPU 25 proceeds to S1.
Proceed to 102 to start collecting data serving as parameters indicating the engine operating state.

The above data includes, for example, the output signal value (intake air amount) of the air flow meter 8: GA, the fuel injection amount: TAU, the engine speed: NE, the output signal value of the throttle position sensor 7 (throttle opening degree). ): TA,
Output signal value of vehicle speed sensor 32 (vehicle speed): Load of auxiliary devices such as SPD and air conditioner compressor: LOA
D and the like.

In S1103, the CPU 25 sets the valve device 1
A control is executed to return the fully-opened state after the 60 is once fully closed from the fully open state. In S1104, the CPU 25
The data collection process started in S1102 ends.

In step S1105, the CPU 25 executes the processing in step S1.
Referring to the data collected from step 102 to step S1104, the internal combustion engine 1 is controlled while the valve device 160 is temporarily changed from the fully open state to the fully closed state and then returned to the fully open state.
It is determined whether or not the operation state is stable.

More specifically, the CPU 25 refers to the collected data, and the EGR valve 22a is in the fully closed state (EGR control is continuously in a non-execution state), and the throttle valve 6 Amount of change: ΔTA is a predetermined value: TACONST
The following is the amount of change in vehicle speed: △ SPD is a predetermined value: SPD
If it is less than CONST and the load on the auxiliary equipment is constant, it is determined that the operating state of the internal combustion engine 1 has been stabilized.

If it is determined in step S1105 that the operation state of the internal combustion engine 1 during the control of returning the valve device 160 from the fully open state to the fully closed state and then returning to the fully open state is not stable, the CPU 25 , S1106, and deletes the data collected from S1102 to S1104. Then, the processes after S1101 are executed again.

On the other hand, at S1105, the valve device 16
If it is determined that the operation state of the internal combustion engine 1 during the control of returning the fully open state from the fully open state to the fully open state and then performing the control to return to the fully open state has been stabilized, the CPU 25 proceeds to S1107 and proceeds from S1102 to Based on the data collected in S1104, the amount of change in the engine speed when the control for changing the valve device 160 from the fully open state to the fully closed state is performed:
ΔNE and the change amount of the fuel injection amount: ΔTAU are calculated, and the change amount of the engine speed is determined to be a predetermined reference engine speed change amount: C
HEKNE or more and the amount of change in the fuel injection amount:
ΔTAU is a predetermined reference fuel injection change amount: CHEKTAU
It is determined whether or not this is the case.

When the control for changing the valve device 160 from the fully open state to the fully closed state in S1107 is performed, the engine speed change amount: △ NE is the reference engine speed change amount: CHEK.
If it is determined that NE is equal to or more than the change amount of the fuel injection amount: ΔTAU is equal to or more than the reference fuel change amount: CHEKTAU,
Proceeding to S1108, it is determined that the valve device 160 is normal, and the execution of this routine ends.

On the other hand, in S1107, the valve device 16
Change in engine speed when control is performed to change 0 from the fully open state to the fully closed state: △ NE is the reference engine speed change: C
Less than HEKNE and / or variation in fuel injection amount: ΔT
If it is determined that the AU is less than the reference fuel change amount: CHEKTAU, the CPU 25 proceeds to S1109 and determines that an abnormality has occurred in the valve device 160.

Subsequently, the CPU 25 proceeds to S1110, outputs warning information indicating that an abnormality has occurred in the valve device 160, and ends the execution of this routine. As described above, when the CPU 25 executes the failure diagnosis control routine, the engine speed detection means according to the present invention
A fuel injection amount detection unit and a failure diagnosis unit are realized.

Therefore, according to the present embodiment, even in a mass flow type internal combustion engine in which the amount of intake air is directly detected by an air flow meter, a pressure sensor or the like for detecting the pressure in the intake pipe is provided. Therefore, it is possible to determine the failure of the valve device 160.

<Other Embodiment> Another embodiment according to the present invention will be described with reference to the drawings. Here, a configuration different from the above-described embodiment will be described, and a description of the same configuration will be omitted.

In the above-described embodiment, an example has been described in which the present invention is applied to a mass flow type internal combustion engine having no sensor for detecting the pressure of the intake pipe. Is applied to a speed-density type internal combustion engine that estimates from the engine speed and the intake pipe pressure.

FIG. 12 is a diagram showing a schematic configuration of a speed-density type internal combustion engine to which the failure diagnosis device according to the present invention is applied. In FIG. 12, the internal combustion engine 1 itself includes:
This is the same as the first embodiment described above, and is a four-cycle four-cylinder internal combustion engine. In the intake system of the internal combustion engine 1,
Instead of an air flow meter attached to the intake pipe 4, a pressure sensor 33 for detecting the pressure (intake pipe pressure) in the surge tank 3 is attached to the surge tank 3.

As shown in FIG. 13, the pressure sensor 33 is connected to the A / D converter 3 of the ECU 23 via electric wiring.
The A / D converter 31 converts the output signal value of the pressure sensor 31 from an analog signal format to a digital signal format, and then inputs the converted signal value to the input port 29. Then, the CPU 25 and the RAM 2
7 is transmitted.

Next, the valve device 160 according to the present embodiment will be described.
Will be described. When the operating state of the internal combustion engine 1 is in the idling operation range, the CPU 25
A failure diagnosis of the valve device 160 is performed according to a third failure diagnosis control routine as shown in FIG.

In the third failure diagnosis control routine, the CPU
In step S1401, it is determined whether the failure diagnosis condition of the valve device 160 is satisfied. S140
If it is determined in step 1 that the failure diagnosis condition is not satisfied, the CPU 25 repeatedly executes the processing of S1401 until the failure diagnosis condition is satisfied.

If it is determined in S1401 that the failure diagnosis condition is satisfied, the CPU 25 proceeds to S1.
Proceeding to 402, collection of data serving as a parameter indicating the engine operating state is started.

The above data includes, for example, an output signal value (intake pipe pressure) of the pressure sensor 33: PM, a fuel injection amount: TAU, an engine speed: NE, an output signal value of the throttle position sensor 7 (throttle opening degree). ): TA, output signal value (vehicle speed) of the vehicle speed sensor 32: SPD, load of accessories such as air conditioner compressor: LOAD, etc.

In S1403, the CPU 25 sets the valve device 1
A control is executed to return the fully-opened state after the 60 is once fully closed from the fully open state. In S1404, the CPU 25
The data collection process started in S1402 ends.

In step S1405, the CPU 25 executes the processing in step S1.
Referring to the data collected from step 402 to step S1404, the internal combustion engine 1 is controlled while the valve device 160 is temporarily changed from the fully open state to the fully closed state and then returned to the fully open state.
It is determined whether or not the operation state is stable.

More specifically, the CPU 25 refers to the collected data, and the EGR valve 22a is in the fully closed state (the EGR control is continuously in a non-executing state), and the internal combustion engine 1 If the idling operation state is continued, the throttle opening is continuously “0”, and the load on the accessories is constant, it is determined that the operation state of the internal combustion engine 1 is stable.

If it is determined in step S1405 that the operation state of the internal combustion engine 1 during the control of returning the valve device 160 from the fully open state to the fully closed state and then to the fully opened state is not stable, the CPU 25 Then, the process proceeds to S1406, the data collected from S1402 to S1404 is deleted, and then the processes after S1401 are executed again.

On the other hand, in S1405, the valve device 16
If it is determined that the operation state of the internal combustion engine 1 during the control of returning the fully open state from the fully open state to the fully open state is performed, the CPU 25 proceeds to S1407, and proceeds from S1402 to the above. Based on the data collected in S1404, the amount of change in the engine speed when the control for changing the valve device 160 from the fully open state to the fully closed state is performed:
ΔNE and the change amount of the fuel injection amount: ΔTAU are calculated, and the change amount of the engine speed is determined to be a predetermined reference engine speed change amount: C
HEKNE or more and the amount of change in the fuel injection amount:
ΔTAU is a predetermined reference fuel injection change amount: CHEKTAU
It is determined whether or not this is the case.

Since the exhaust resistance of the bypass passage in the suction mechanism 15 is larger than the exhaust resistance of the main exhaust passage,
When the valve device 160 is normal, the pressure in the exhaust passage increases due to the valve body 162 operating from the fully open state to the fully closed state, and this pressure acts on the internal combustion engine 1 as back pressure. At this time, the back pressure becomes a resistance of the operation of discharging the burned gas from the cylinder during the exhaust stroke, whereby the degree of negative pressure in the cylinder decreases in the next intake stroke, and the intake pipe pressure changes to the atmosphere side.

In the internal combustion engine of the speed density system, the mass of air sucked into the internal combustion engine in one cycle of the intake stroke: GA is _{calculated by the following} equation based on the equation of state of gas: V _c
/ G · R · (PM / θ) · η _v , (Vc: cylinder volume, g: gravitational acceleration, R: gas constant, PM: absolute pressure in the intake pipe, θ: intake temperature, η _v : volumetric efficiency (engine rotation number,
The basic injection amount of the fuel: TP is estimated according to a function using the opening / closing timing of the intake / exhaust valve, the exhaust pipe pressure, the EGR amount, and the like as parameters. When the value of the intake pipe pressure: PM increases due to the increase in the back pressure as described above, the CPU 25 assumes that the air mass: GA has increased and increases the basic injection amount: TP. As a result, an increase in the fuel injection amount: TAU and an increase in the engine speed: NE occur.

That is, when the valve device 160 is normal, as shown in FIG. 15, when the back pressure rises due to the operation of the valve body 162, and the intake pipe pressure PM increases accordingly, the intake air amount decreases. The fuel injection amount is considered as increased:
TAU is increased by a predetermined amount or more, and as a result, the engine speed:
NE rises above a predetermined number of revolutions.

Therefore, in the present embodiment, based on the above knowledge, the amount of change in the fuel injection amount when the valve device 160 is controlled from the fully opened state to the fully closed state: ΔTAU and the engine speed A change amount: △ NE is calculated, and a change amount of the fuel injection amount: △ TAU is a reference fuel injection change amount: CHEKTAU.
When the engine speed change amount △ NE is equal to or greater than the reference engine speed change amount: CHEKNE, the valve device 1
60 is determined to be normal, and the amount of change in the fuel injection amount: ΔT
If AU is less than the reference fuel injection change amount: CHEKTAU and / or the engine speed change amount △ NE is less than the reference engine speed change amount: CHEKNE, it is determined that an abnormality has occurred in the valve device 160.

Here, returning to the third failure diagnosis control routine of FIG. 14, the amount of change in engine speed: △ NE when the control for changing the valve device 160 from the fully open state to the fully closed state in S1407 is performed Reference engine speed change: CHEKN
If it is determined that E is equal to or more than the change amount of the fuel injection amount: ΔTAU is equal to or more than the reference fuel change amount: CHEKTAU,
The PU 25 proceeds to S1408, deems that the valve device 160 is normal, and ends the execution of this routine.

On the other hand, in S1407, the valve device 16
Change in engine speed when control is performed to change 0 from the fully open state to the fully closed state: △ NE is the reference engine speed change: C
Less than HEKNE and / or variation in fuel injection amount: ΔT
If it is determined that the AU is less than the reference fuel change amount: CHEKTAU, the CPU 25 proceeds to S1409 and determines that an abnormality has occurred in the valve device 160.

Subsequently, the CPU 25 proceeds to S1410, outputs warning information indicating that an abnormality has occurred in the valve device 160, and ends the execution of this routine.
When the operating state of the internal combustion engine 1 is in the idling operation region, the degree of negative pressure of the intake pipe pressure increases, so that the fluctuation of the intake pipe pressure toward the atmosphere due to the opening / closing operation of the valve device 160 becomes remarkable. Since the change amount of the fuel injection amount and the change amount of the engine speed also become remarkable accordingly, the failure diagnosis is performed using only one of the change amount of the engine speed and the change amount of the fuel injection amount as a parameter. It may be.

Next, when the failure diagnosis of the valve device 160 is performed when the operation state of the internal combustion engine 1 is in the non-idle operation region and the engine load is constant at a predetermined load or less, C
The PU 25 executes a fourth failure diagnosis control routine as shown in FIG.

In the fourth failure diagnosis control routine, the CPU
In step S1601, it is determined whether the failure diagnosis condition of the valve device 160 is satisfied. S160
If it is determined in Step 1 that the failure diagnosis condition is not satisfied, the CPU 25 repeatedly executes the process of S1601 until the failure diagnosis condition is satisfied.

If it is determined in S1601 that the failure diagnosis condition is satisfied, the CPU 25 proceeds to S1.
Proceeding to 602, collection of data serving as a parameter indicating the engine operating state is started.

As the data described above, the pressure sensor 33
Output signal value (intake pipe pressure): PM, fuel injection amount: TA
U, engine speed: NE, throttle position sensor 7
Output signal value (throttle opening): TA, vehicle speed sensor 3
Output signal value of 2 (vehicle speed): SPD, load of auxiliary equipment such as air conditioner compressor: LOAD, etc.

In S1603, the CPU 25 sets the valve device 1
A control is executed to return the fully-opened state after the 60 is once fully closed from the fully open state. In S1604, the CPU 25
The data collection process started in S1602 is ended.

In step S1605, the CPU 25 executes the processing in step S1.
With reference to the data collected from S602 to S1604, the internal combustion engine 1 is controlled during the control of returning the valve device 160 from the fully open state to the fully closed state and then back to the fully open state.
It is determined whether or not the operation state is stable.

Specifically, referring to the collected data, the CPU 25 determines that the fully closed state of the EGR valve 22a has been continued (the EGR control has been continuously performed and is not executed), Amount of change: ΔTA is a predetermined value: TACONST
The following is the amount of change in vehicle speed: △ SPD is a predetermined value: SPD
If it is less than CONST and the load on the auxiliary equipment is constant, it is determined that the operating state of the internal combustion engine 1 has been stabilized.

If it is determined in step S1605 that the operation state of the internal combustion engine 1 during the control of returning the valve device 160 from the fully opened state to the fully closed state and then returning to the fully open state is not stable, the CPU 25 The process proceeds to S1606 to delete the data collected from S1602 to S1604, and then executes the processes from S1601 onward again.

On the other hand, in S1605, the valve device 16
If it is determined that the operation state of the internal combustion engine 1 during the control of returning the fully open state from the fully open state to the fully open state and then performing the control to return to the fully open state is stable, the CPU 25 proceeds to S1607 and proceeds from S1602 to S1607. Based on the data collected in S1604, the amount of change in the engine speed when the control for changing the valve device 160 from the fully open state to the fully closed state is performed:
ΔNE and the change amount of the fuel injection amount: ΔTAU are calculated, and the change amount of the engine speed is determined to be a predetermined reference engine speed change amount: C
HEKNE or more and the amount of change in the fuel injection amount:
ΔTAU is a predetermined reference fuel injection change amount: CHEKTAU
It is determined whether or not this is the case.

When the control for changing the valve device 160 from the fully open state to the fully closed state is performed in S1607, the engine speed change amount: △ NE is the reference engine speed change amount: CHEK.
If it is determined that NE is equal to or more than the change amount of the fuel injection amount: ΔTAU is equal to or more than the reference fuel change amount: CHEKTAU,
Proceeding to S1608, it is considered that the valve device 160 is normal, and the execution of this routine ends.

On the other hand, in S1607, the valve device 16
Change in engine speed when control is performed to change 0 from the fully open state to the fully closed state: △ NE is the reference engine speed change: C
Less than HEKNE and / or variation in fuel injection amount: ΔT
If it is determined that the AU is less than the reference fuel change amount: CHEKTAU, the CPU 25 proceeds to S1609, and determines that an abnormality has occurred in the valve device 160.

Subsequently, the CPU 25 proceeds to S1610, outputs warning information indicating that an abnormality has occurred in the valve device 160, and ends the execution of this routine. In the embodiment described above, even in a speed-density type internal combustion engine in which the intake air amount is estimated from the intake pipe pressure and the engine speed, the valve device 160 is determined based on the change in the engine speed and / or the fuel injection amount. Can be diagnosed.

In the case of a speed-density internal combustion engine, one of the parameters for determining the fuel injection amount is set to 1
Although the intake pipe pressure is used, the intake pipe pressure is estimated using the intake pipe pressure as a parameter, the basic fuel injection quantity is determined based on the estimated intake air quantity, and the basic injection quantity is corrected in various ways. In the process of determining the final fuel injection amount by correcting based on the items, changes in the atmospheric pressure due to changes in altitude and fluctuations in the intake pipe pressure due to intake pulsation are smoothed out. Compared to the case where the intake pipe pressure is used, the influence of the intake pulsation and the change of the altitude is less likely to occur, and the misjudgment is more difficult. In the above-described embodiment, when the control for changing the valve device 160 from the fully open state to the fully closed state is performed, in other words, the amount of change in the engine speed and / or the fuel injection amount when the back pressure should increase. Has been described, the engine speed and / or the fuel injection amount when the control for bringing the valve device 160 from the fully closed state to the fully open state is performed, that is, when the back pressure should be reduced. The failure diagnosis may be performed based on the amount of change in.

In the above embodiment, the adsorbent 1
The example in which the failure diagnosis is performed after the completion of the desorption of the unburned fuel component adsorbed on the fuel cell 52 has been described. Is performed, or the adsorbent 15
2 is completed, and the valve device 160
The failure diagnosis may be performed when the control for changing the state from the fully closed state to the fully open state is performed.

Further, in the above-described embodiment, an exhaust valve in an exhaust gas purification device provided with an adsorbent has been described as an example of an exhaust valve to be subjected to failure diagnosis. However, the present invention is not limited to this. Any type of exhaust valve may be used as long as the exhaust valve is provided in the exhaust passage of which the back pressure changes by opening and closing operations.

[0164]

The exhaust valve failure diagnosis apparatus according to the present invention has the following features.
Since the valve mechanism is configured to diagnose a failure of the valve mechanism based on a change in the fuel injection amount and / or a change in the engine speed caused by a change in the back pressure when the valve mechanism is driven to open and close, the method depends on the detection method of the intake air amount. The present invention can be applied to any internal combustion engine, and a highly accurate failure diagnosis can be performed without being affected by noise such as a change in atmospheric pressure or intake pulsation.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which a failure diagnosis device according to an embodiment is applied.

FIG. 2 is a diagram (1) showing an internal configuration of a suction mechanism.

FIG. 3 is a diagram (2) showing an internal configuration of a suction mechanism.

FIG. 4 is a diagram illustrating the operation of the valve device.

FIG. 5 is a diagram (1) illustrating a configuration of an adsorption mechanism suitable for making exhaust resistance different between a main exhaust passage and a bypass passage.

FIG. 6 is a diagram (2) for explaining a configuration of an adsorption mechanism suitable for making exhaust resistance different between a main exhaust passage and a bypass passage.

FIG. 7 is a diagram (3) for explaining a configuration of an adsorption mechanism suitable for making exhaust resistance different between a main exhaust passage and a bypass passage.

FIG. 8 is a block diagram showing an internal configuration of an ECU.

FIG. 9 is a diagram showing a first failure diagnosis control routine.

FIG. 10 is a time chart showing a change in the engine operating state caused by the opening and closing operation of the valve device in a normal state.

FIG. 11 is a diagram showing a second failure diagnosis control routine.

FIG. 12 is a diagram showing another embodiment of the internal combustion engine to which the failure diagnosis device is applied.

FIG. 13 is a block diagram showing an internal configuration of an ECU according to another embodiment.

FIG. 14 is a diagram illustrating a third failure diagnosis control routine.

FIG. 15 is a time chart illustrating a change in the engine operating state caused by the opening and closing operation of the valve device in a normal state.

FIG. 16 is a diagram showing a fourth failure diagnosis control routine.

[Explanation of symbols]

 1 ··· Internal combustion engine 3 ··· Surge tank 4 ··· Intake pipe 8 ··· Air flow meter 12 ··· Exhaust branch pipe 13 ··· Exhaust pipe 13a ··· Upstream exhaust pipe 13b · -Downstream exhaust pipe 14-Three-way catalyst 15-Adsorption mechanism 20-Crank position sensor 21-Water temperature sensor 22-Exhaust recirculation pipe 22a-Flow control valve 23-ECU 25 ... CPU 160 ... valve device 161 ... housing 162 ... valve body 163 ... shaft 164 ... passage 165 ... bearing 166 ... actuator

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Hoshi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. F-term (reference) 3G065 AA04 CA35 DA06 EA03 GA05 GA10 GA11 GA18 GA37 GA41 KA02 KA12 3G091 AA02 AA11 AB03 AB13 BA14 BA15 BA19 CA13 CA26 CB02 CB07 EA01 EA04 EA05 EA07 EA08 EA39

Claims (8)

[Claims] A valve mechanism provided in an exhaust passage of the internal combustion engine; an engine speed detecting means for detecting an engine speed of the internal combustion engine; and an engine speed when an opening of the valve mechanism is changed. And a failure diagnosis means for performing a failure diagnosis of the valve mechanism based on a change of the exhaust valve. 2. A bypass passage bypassing a main exhaust passage in an exhaust passage of the internal combustion engine, an exhaust valve for switching an exhaust flow to the main exhaust passage and the bypass passage, and detecting an engine speed of the internal combustion engine. An engine speed detecting means for performing a fault diagnosis of the exhaust valve based on a change in the engine speed when the opening of the exhaust valve is changed. Valve failure diagnosis device. 3. A bypass passage bypassing a main exhaust passage in an exhaust passage of the internal combustion engine, an exhaust valve switching an exhaust flow to the main exhaust passage and the bypass passage, and detecting a fuel injection amount of the internal combustion engine. A fuel injection amount detecting unit that performs a failure diagnosis of the exhaust valve based on a change in the fuel injection amount when the opening of the exhaust valve is changed. Valve failure diagnosis device. 4. The failure diagnosis means according to claim 2, wherein said failure diagnosis means performs a failure diagnosis of said exhaust valve on condition that an operation state of said internal combustion engine is in a constant load operation region. A failure diagnosis device for the exhaust valve according to the above. 5. The failure diagnosis unit according to claim 2, wherein the failure diagnosis unit performs the failure diagnosis of the exhaust valve on condition that an operation state of the internal combustion engine is in a constant low load operation region.
4. The exhaust valve failure diagnostic device according to claim 3, wherein: 6. The failure diagnosis device for an exhaust valve according to claim 2, wherein exhaust gas purification means for purifying exhaust gas is provided in the bypass passage. 7. The exhaust gas purifying means is an adsorbent for adsorbing unburned fuel components contained in the exhaust gas, and the failure diagnosing means is configured to detect the air-fuel ratio of the exhaust gas downstream of the adsorbent when the air-fuel ratio is lean. 7. The exhaust valve failure diagnosis device according to claim 6, wherein the exhaust valve failure diagnosis is performed. 8. The exhaust valve failure diagnostic device according to claim 6, wherein said failure diagnostic means performs a failure diagnosis of said exhaust valve after the completion of warming-up of said internal combustion engine.