JP2002155814A - Intake system evaporative fuel leakage preventing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of an intake system evaporative fuel leakage preventing device. SOLUTION: A housing 10a of an air cleaner 10 in an intake passage 7 is internally equipped with an on-off valve 30 closable by a given set point or lower of an intake flow rate passing the intake passage to close a connection opening 10b in the housing into an air intake nozzle 17. During an engine stop, the on-off valve is closed to close the connection opening 10b and thus prevent emission of fuel vapor generated in the intake passage from the nozzle 17 to the atmosphere. The on-off valve 30 has a valve element 30a of a flat plate shape, and closes the opening 10b through surface contact with the periphery of the connection opening 10b. The vale element is thus protected against a malfunction due to entrainment of foreign matter and the like in valve element closing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing an intake system from leaking in an internal combustion engine.

[0002]

2. Description of the Related Art When an internal combustion engine is stopped, fuel vapor is generated in an engine intake passage for various reasons. For example, when the fuel supplied to the cylinder combustion chamber during engine operation is accumulated in the cylinder without burning together with the engine stop and evaporates, the fuel vapor flows into the intake passage from the cylinder whose cylinder intake valve is open while the engine is stopped. Flows out, and fuel vapor fills the intake passage. Also, if fuel adhering in a liquid state remains on the intake port wall surface during operation of the engine, the fuel adhering to the wall surface evaporates while the engine is stopped, and fuel vapor is formed in the intake passage.
Further, in an engine having a fuel injection valve, fuel that has accumulated in the fuel injection valve while the engine is stopped slightly leaks into the intake passage,
Fuel vapor may be formed in the intake passage.

When fuel vapor is generated in the intake passage while the engine is stopped, the generated fuel vapor fills the intake passage and leaks to the atmosphere from the opening (intake port) of the intake passage. This may cause air pollution (so-called intake system evaporation leakage) due to fuel vapor (hydrocarbon). If the intake passage is shut off from the atmosphere while the engine is stopped, for example, it is possible to prevent the fuel vapor filled in the intake passage from leaking to the atmosphere. Further, in an engine having a throttle valve, the intake passage can be shielded from the atmosphere to some extent by holding the throttle valve fully closed while the engine is stopped.

Although it is not intended to prevent the intake system from leaking, for example, Japanese Unexamined Patent Publication No.
In an engine equipped with a throttle valve (electronically controlled throttle valve) driven by an independent actuator (step motor), a spring for constantly biasing the throttle valve body in a fully closed direction is provided, and the biasing force of this spring is applied to the throttle valve. A control device for a throttle valve which is set to be larger than the throttle valve driving force when the step motor to be driven is not energized is described.

In the device disclosed in Japanese Patent Application Laid-Open No. 56-14834, the throttle valve is biased by the spring (2) in the fully closed direction with a force greater than the driving force when the step motor is not energized. When stopped, the throttle valve is held at the fully closed position. For this reason, the intake passage is shut off from the atmosphere by the throttle valve while the engine is stopped, so that fuel vapor generated at the intake port or the like is prevented from leaking to the atmosphere.

[0006]

However, as in the apparatus disclosed in Japanese Patent Application Laid-Open No. 56-14834, the intake passage is cut off from the atmosphere by keeping the throttle valve in the fully closed position while the engine is stopped. A problem may occur if the system evaporation is prevented from leaking. As the throttle valve, a plate valve having the same shape as the cross section of the intake passage is arranged in the intake passage, and the intake passage is opened and closed by rotating the valve around a drive shaft. It is. In this case, in order to shut off the intake passage by using the throttle valve in the fully closed state, the peripheral portion of the valve body of the plate-shaped throttle valve is brought into contact with the intake passage wall, and the peripheral portion of the valve body and the intake passage wall surface are contacted. It is necessary to cut off the intake passage by line contact with the air.

However, when the wall of the intake passage and the peripheral portion of the throttle valve body are brought into close contact with each other in a high temperature state immediately after the engine is stopped to shut off the intake passage, if the temperature of the intake passage or the throttle valve body drops after the engine is stopped. Due to the difference in the thermal expansion coefficient between the throttle valve body and the intake passage wall surface, the contact pressure between the peripheral portion of the throttle valve and the intake passage wall surface becomes excessive, and the throttle valve may stick in the closed state. Thus, if the throttle valve is stuck in the closed state, there is a problem that the engine cannot be started next.

In addition, when the intake valve is cut off by the throttle valve, it is easy to cause the foreign matter to be stuck between the peripheral portion of the throttle valve body and the wall surface of the intake passage due to the mechanism. There is a problem that the malfunction of the throttle valve is relatively likely to occur. Furthermore, when the intake air passage is prevented by shutting off the intake passage by using a throttle valve or the like, it is possible to detect an abnormality even when an abnormality such as a failure in the shut-off due to, for example, distortion of the valve body or perforation occurs. There are difficult problems.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an intake system evaporative leakage prevention device capable of preventing occurrence of an abnormality due to sticking of a valve body. It is another object of the present invention to provide an intake-evaporation-leakage prevention device that can easily and accurately detect an abnormality such as a failure in blocking an intake passage.

[0010]

According to the first aspect of the present invention, the fuel vapor generated in the intake passage is disposed in the intake passage of the internal combustion engine, and is closed when the engine is stopped to close the intake passage. Is an intake system evaporative leak prevention device having an on-off valve that opens during engine operation and allows intake air to pass through the intake passage, while preventing leakage to the atmosphere. A valve body having a planar sealing portion, wherein the intake passage includes a planar sealing portion that comes into contact with the sealing portion of the valve body when the on-off valve is closed, and when the on-off valve is closed. In addition, there is provided an intake-air-evaporation-leakage preventing device, wherein an intake passage is closed by a surface contact between a sealing portion of the valve body and a sealing portion of the intake passage.

In other words, according to the first aspect of the present invention, the on-off valve provided in the intake passage has a planar sealing portion, and the sealing portion is connected to the planar sealing portion provided in the intake passage. The contact blocks the intake passage. This prevents the intake passage from the atmosphere and prevents the fuel in the intake passage from leaking to the atmosphere while the engine is stopped. In addition, since the opening and closing valve and the sealing portion of the intake passage are in surface contact with each other, thereby closing the intake passage, a difference in the coefficient of thermal expansion between the intake passage and the valve body, and an abnormality of the opening and closing valve due to foreign matter being caught may occur. Is prevented.

According to the second aspect of the present invention, the on-off valve closes when the intake flow rate passing through the intake passage is equal to or less than a predetermined set value, and closes when the intake flow rate exceeds the set value. Opening / closing state detecting means for detecting whether the on-off valve is open or closed, intake flow rate detecting means for detecting an intake flow rate passing through the intake passage, and the intake flow rate during engine operation. An intake system comprising: an abnormality determination unit configured to determine whether there is an abnormality in the on-off valve based on an intake flow rate detected by a detection unit and an open / close state of the on-off valve detected by the open / close state detection unit. An evaporative leakage prevention device is provided.

In other words, according to the second aspect of the present invention, the on-off valve closes and shuts off the intake passage when the intake air flow becomes equal to or less than the set value due to the engine stop, and the engine is started so that the intake air flow becomes equal to or more than the set value. The valve will open. Therefore, it is possible to determine whether there is an abnormality in the on-off valve based on the intake air flow rate and the on-off state of the on-off valve during the operation of the engine. For example, if the on-off state detection means detects that the on-off valve is closed while the engine is operating at the intake air flow rate at which the on-off valve should be open, the on-off valve is abnormal. Can be determined to have occurred.

According to the third aspect of the present invention, the set value of the intake flow rate is set to a value smaller than the intake air amount at the time of idling after the completion of engine warm-up, and the abnormality determination means sets the intake flow rate When the intake flow rate detected by the detection means is equal to or greater than a predetermined determination value, and when the open / close state detection means detects that the open / close valve is in the closed state, a leak has occurred in the open / close valve. The determination value is set to a value obtained by adding the allowable maximum leak flow rate to the set value, and the allowable maximum leak flow rate is a value of the fuel leaking from the intake passage to the atmosphere through the on-off valve when the on-off valve is closed. The leak amount is set to a value equal to the intake air amount flowing through the leak when the engine is operated in a state where a leak having a steam flow rate that is an allowable maximum value occurs in the on-off valve. 2
2. An intake system evaporation prevention device according to (1) is provided.

That is, according to the third aspect of the present invention, the abnormality determining means detects an abnormality as to whether or not the on-off valve has leaked. For example, if holes and distortions occur in the on-off valve and fuel vapor in the intake passage leaks to the atmosphere even when the valve is closed, the magnitude of the leakage depends on the magnitude of the holes and distortions on the on-off valve. Increase. Leakage of fuel vapor into the atmosphere can be tolerated if the amount is small, but if it exceeds a certain level, it becomes unacceptable due to air pollution. Further, when a leak occurs in the on-off valve, the intake air flows into the intake passage through the leak even during engine operation. For this reason, during engine operation, the on-off valve, which should be opened when the engine intake flow rate reaches the set value, and when leakage occurs, the intake flow rate passes through the on-off valve leak and enters the intake passage. The valve will not be opened unless it becomes larger than the set value by the amount of the inflowing intake air.

According to the present invention, when a leakage of the fuel vapor at the time of stopping the engine reaches the above-mentioned allowable limit in the on-off valve, the set value and the intake flow rate (leakage) passing through the leakage during the operation of the engine. And the flow rate) is stored as a determination value. If the on-off valve is not opened when the engine intake flow rate becomes larger than the determination value during engine operation, it is determined that the on-off valve has leaked. judge. This makes it possible to easily and accurately detect that a leak having a size larger than an allowable limit has occurred in the on-off valve.

According to the fourth aspect of the present invention, the abnormality determining means determines that the intake flow rate detected by the intake flow rate detecting means is smaller than the determination value, and that the open / close valve is opened by the open / closed state detecting means. The intake system evaporative leakage prevention device according to claim 3, wherein when the valve state is detected, the on-off valve is determined to be normal. In other words, in the invention of claim 4, if the engine intake flow rate is smaller than the determination value in claim 3, and the on-off valve is being opened, the on-off valve is opened in a state where there is no leakage and there is an intake flow. Will be. For this reason, the on-off valve is determined to be normal because there is no abnormality such as leakage or valve opening failure.

According to a fifth aspect of the present invention, the engine includes idle-up means for performing an idling-up operation for increasing an idling speed according to a load on an engine accessory during idling operation. Further, when the idle-up operation is performed by the idle-up device after the engine warm-up is completed, the intake flow rate detected by the intake flow-rate detection device after the engine auxiliary device is stopped and the intake flow rate detected by the opening / closing state detection device are detected. 5. The intake-evaporation-leakage prevention device according to claim 4, wherein it is determined whether or not the on-off valve is normal based on the on-off state of the on-off valve.

That is, in the invention of claim 5, for example,
An idle-up unit is provided for increasing the idle speed during operation of an air conditioner or an auxiliary machine for increasing an electric load to prevent a stall of the engine. In the invention of claim 4, the abnormality determination means determines whether the on-off valve is normal when the intake air flow rate of the engine is equal to or less than the determination value. On the other hand, when the idle-up means is performing the idle-up operation, the intake air flow rate of the engine is larger than the intake air flow rate during the idle operation when the auxiliary machine is not operating. Intake flow rate is also larger than the judgment value,
It may not be possible to determine whether the on-off valve is normal. For this reason, in the present invention, when the idle-up means is operating, it is determined whether or not the on-off valve is normal after stopping the auxiliary equipment. This prevents the frequency of execution of the determination as to whether the on-off valve is normal from being reduced.

According to the sixth aspect of the present invention, the engine includes idle-up means for performing an idling-up operation for increasing an idling speed according to a load on an engine accessory during idling operation. Further, when the idling-up operation is being performed by the idling-up means, the idling-up operation is forcibly stopped during a fuel cut operation in which fuel supply to the engine is stopped when the engine is decelerated. The leak prevention for an intake system according to claim 4, wherein it is determined whether or not the on-off valve is normal based on an intake air flow rate detected by the control unit and an on-off state of the on-off valve detected by the on-off state detection means. An apparatus is provided.

That is, according to the invention of claim 6, claim 5
Is provided. In the invention according to claim 5, the abnormality determination means determines whether or not the on-off valve is normal after stopping the operation of the auxiliary device. For example, in a state where a load such as a headlight of a vehicle is operating, Since the headlights cannot be turned off for vehicle traveling safety, normal judgment cannot be made. Therefore, in the present invention, the determination is made by stopping the idle-up operation by the idle-up means without stopping the operation of the auxiliary machine.
In this case, the engine may stall if the idling operation is stopped while the load is operating during the normal idling operation. According to the present invention, when the fuel cut operation is performed during deceleration while the vehicle is running, the idling operation is stopped and the normality of the on-off valve is determined, thereby increasing the frequency of performing the determination while preventing the engine from being stalled. ing.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a schematic configuration of an intake system according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a cylinder intake valve of an internal combustion engine, and 3 denotes an intake port. The intake port of each cylinder is connected to a surge tank 7b via an intake manifold 7a. Surge tank 7b
Is connected to a nozzle 17 as an air inlet through an intake passage 7 and an air cleaner 10. In FIG. 1, reference numeral 10a denotes a housing of the air cleaner 10, and reference numeral 10b denotes an opening of the housing 10a of the nozzle 17. Also,
A throttle valve 9 is arranged on the intake passage 7.

In FIG. 1, reference numeral 5 denotes a fuel injection valve provided at the intake port 3 of each cylinder. The fuel injection valve 5 injects fuel supplied from a fuel supply pipe (not shown) to each intake port during operation of the engine, and causes each cylinder to take in fuel along with intake air. A filter element 15 is provided in an intake passage of the air cleaner 10. During the operation of the engine, a part of the fuel injected from the fuel injection valve 5 adheres to the wall surface of the intake port 3 in a liquid state to form fuel adhered to the wall surface. The fuel adhered to the wall gradually evaporates to a fuel vapor after the engine is stopped. Also, when the engine is stopped, the fuel held in the fuel injection valve slightly leaks from the fuel injection valve to the intake port, so-called oil-tight leakage of the fuel injection valve may occur. The outflowing fuel evaporates and becomes fuel vapor during stoppage of the engine similarly to the fuel deposited on the wall. Therefore, while the engine is stopped, the intake port 3, the intake manifold 7b, the surge tank 7a, and the intake passage 7 are filled with fuel vapor.

When the fuel vapor fills the intake passage 7 while the engine is stopped, the fuel vapor leaks from the intake passage 7 through the filter element 15 of the air cleaner 10 to the nozzle 17, and
Further, the gas flows out from the suction port 17a of the nozzle 17 to the atmosphere. In this embodiment, in order to prevent the fuel vapor in the intake passage 7 from being released to the atmosphere through the nozzle inlet 17a, the nozzle 17 connection opening 1 in the air cleaner 10 is prevented.
An on-off valve 30 for opening and closing Ob is provided.

In the present embodiment, the on-off valve 30 is a thin plate-shaped valve body 30a made of a lightweight metal or rigid resin and is connected to the nozzle 17 connection portion 10b of the housing 10a of the air cleaner 10.
And a hinge 30b. A spring (not shown) is provided on the hinge 30b.
The valve element 30a of the on-off valve 30 is constantly urged toward the valve closing position indicated by the solid line in FIG. As will be described later, in the present embodiment, the urging force of this spring is such that when the intake air flow rate reaches a predetermined set value, the valve element of the on-off valve 30
Is set apart from the nozzle connection portion 10b.

The on-off valve 30 has a larger area than the nozzle connection opening 10b of the housing 10a, and when there is no intake air flow while the engine is stopped, the housing 10a is driven by its own weight and the urging force of the spring. And is in close contact with the housing wall around the nozzle connection opening 10b. In the present embodiment, the flat portion near the periphery of the valve body 30 that comes into contact with the housing wall surface around the opening 10b functions as a sealing portion on the opening and closing valve side, and the wall surface of the housing 10 around the opening 10b forms a sealing portion on the intake passage side. Function as Both of these sealing portions are formed in a smooth planar shape. When these sealing portions come into surface contact with each other, the opening 10b is closed, and the air cleaner 10 and the intake passage 7 on the upstream side thereof are isolated from the atmosphere. Is done.

Therefore, when the on-off valve 30 moves to the valve closing position (the position indicated by the solid line in FIG. 1) when the engine is stopped, the steam generated in the intake passage 7 is prevented from leaking to the atmosphere. Further, when the engine is started, the on-off valve 30 moves to the valve opening position (the position shown by the dotted line in FIG. 1) due to the negative pressure in the intake passage 7 at the time of starting, and is opened by the intake air flowing from the nozzle 17. Is held. The intake flow rate at which the on-off valve 30 separates from the wall surface of the housing 10a, that is, the intake flow rate at which the connection opening 10b is opened, is controlled by the urging force of a spring provided at the hinge 30b of the valve body 30a. It is set in advance to a predetermined set flow rate smaller than the flow rate.

In the present embodiment, the on-off valve is a flat sealing portion of the valve body 30a and the nozzle connection opening 1 of the housing 10a.
The intake passage is closed by surface contact with the sealing portion around 0b. Therefore, even if there is a difference in the coefficient of thermal expansion between the valve body 30a and the housing 10a, the valve body 30a does not stick. Further, even when foreign matter enters between the sealing portion of the valve body 30a and the sealing portion on the housing 10a side, the valve opening operation of the valve body 30a does not hinder, and the valve body 30 due to the foreign matter biting does not interfere.
a does not stick.

Next, detection of an abnormality of the on-off valve in FIG. 1 will be described. In the present embodiment, an open / closed state detection sensor 33 in the form of, for example, a contact switch is provided near the nozzle connection opening 10b of the housing 10a. The open / closed state detection sensor 33 is configured such that the valve body of the open / close valve 30 is connected to the nozzle connection port 1.
0b is closed, that is, when the sealing portion of the valve body 30a is in contact with the sealing portion around the nozzle connection port 10b of the housing 10a, the valve closing signal (ON signal) is output by the sealing portion. When it is separated, a valve opening signal (OFF signal) is generated.

In this embodiment, an air flow meter 35 is provided in the intake passage 7 to generate a voltage signal corresponding to the flow rate of intake air sucked into the nozzle 17. In the present embodiment, an electronic control unit (ECU) 40 that performs engine control is provided. The ECU 40 includes a microcomputer having a known configuration. The ECU 40 includes an open / closed state of the on-off valve 30 detected by the open / closed state detection sensor 33 and an intake passage 7 detected by the air flow meter 35.
An abnormality determination operation for determining whether or not there is an abnormality in the on-off valve 30 based on the intake flow rate passing through the valve.

For this operation, the output of the air flow meter 35 is input to an input port of the ECU 40 via an AD converter (not shown), and the output of the open / closed state detection sensor 33 is input directly to the input port of the ECU 40. The following four types can be considered as the types of abnormalities that occur in the intake system evaporation prevention device of the type shown in FIG.

(1) Insufficient closing of the on-off valve 30 when the engine is stopped (the valve is stuck open). (2) Opening failure of the on-off valve 30 during engine operation (closed valve sticking). (3) Leakage (opening) of the on-off valve 30. (4) Abnormality of the open / closed state detection sensor (fixation, disconnection, etc.). Hereinafter, a method for determining each abnormality in the present embodiment will be described.

A. (1) Poor closing of the on-off valve 30 when the engine is stopped, and (4) Abnormality of the on-off state detection sensor. The closing failure of the on-off valve 30 is, for example, an abnormality in which the on-off valve 30 is stuck in the open state and cannot close the intake passage when the engine is stopped. This abnormality can be detected by the output of the open / closed state detection sensor 33 when the engine main switch is turned on immediately before starting the engine start operation.

That is, when the engine is stopped, the on-off valve 30 should be closed if it is normal, and the output of the on-off state detection sensor 33 should be on. For this reason, if the output of the sensor 33 is turned off before the engine is started, it is determined that the valve closing failure of the on-off valve 30 or the abnormality of the sensor 33 (fixed contact or disconnection in the off state) has occurred. can do.

B. (2) Opening failure of the on-off valve 30 during engine operation and (4) Abnormality of the on-off state detection sensor. The valve opening failure of the on-off valve 30 means, for example, an opening degree at which the output of the on-off state detection sensor 33 is turned off even when the engine is started even when the on-off valve 30 is stuck in a closed state while the engine is stopped. The valve does not open. This abnormality can be determined based on the output of the open / closed state detection sensor when the intake air flow rate is small, such as during idling after the engine is started. That is, in the present embodiment, the intake flow rate at which the on-off valve 30 is opened is set to a value smaller than the intake flow rate corresponding to the idling operation after the engine warm-up is completed. When operating at (intake flow rate slightly larger than the set intake flow rate of the on-off valve 30), the on-off valve 30 should be open if it is normal. Therefore, if the output of the open / closed state detection sensor 33 is ON in this state, the open / close valve 30 is stuck in the closed state, or a relatively small leak occurs, or the open / closed state detection sensor 33 It is found that either of the above cases is abnormal (fixed contact in the ON state).

Conversely, if the output of the sensor 33 is off when the engine is operating at a low intake air flow rate such as an idle operation, the sensor 33 is abnormal (fixed contacts or broken wires in the off state). As long as there is no operation, the operation of the on-off valve is normal, and no large leakage has occurred. Accordingly, in this state, if the output of the sensor 33 is off and the output of the open / closed state detection sensor is on before the engine is started, it can be determined that both the open / close valve 30 and the sensor 33 are normal.

C. (3) Leakage (opening) of the on-off valve 30 and (4) Abnormality of the on-off state detection sensor. In the present embodiment, a case where a relatively large leak occurs when the on-off valve is closed is detected. When the valve body 30a of the on-off valve 30 is distorted or has a hole, fuel vapor generated in the intake passage during engine stoppage leaks to the atmosphere through the distorted portion or the hole of the valve body, and an evaporative leak occurs. . However, since the fuel vapor pressure is not so high in practice, there is no problem of evaporative leakage unless the leakage of the on-off valve exceeds a certain level. Therefore, in the present embodiment, a case where a leak having a size equal to or larger than a level that causes a problem of the evaporation leak in the on-off valve 30 is determined to be a leak abnormality.

If the valve body of the on-off valve 30 leaks, not only does fuel vapor leak to the atmosphere through the leak when the engine is stopped, but also the intake air leaks while the on-off valve 30 remains closed during engine operation. Since the engine flows into the passage, the on-off valve 30 does not open unless the engine intake air flow exceeds the set value of the on-off valve and does not increase more than a certain level. In the present embodiment, the engine is operated in a state where a hole in which a minimum leak (allowable maximum leak) in which deterioration of the evaporation leak becomes a problem is provided in the valve body 30a of the on-off valve 30 in advance, and after the engine warm-up is completed. The minimum intake air flow A at which the on-off valve 30 opens is measured. This intake flow rate A
Is the sum of the set valve opening flow rate of the on-off valve 30 and the leakage flow rate passing through the on-off valve leakage. In this embodiment, the engine uses the sum A of the preset flow rate of the opening of the on-off valve 30 and the leakage flow rate passing through the leakage of the on-off valve as the determination flow rate as described above, and determines whether the intake air having a flow rate equal to or more than the determination flow rate If the output of the open / close state detection sensor 33 is ON (the open / close valve is closed) during the operation at the flow rate, a leak exceeding the allowable maximum leak has occurred in the open / close valve 30 or the open / close state is detected. It can be determined that the sensor 33 is abnormal (the ON state of the contact is fixed).

The above description is directed to a case in which a leak greater than the allowable maximum leak occurs in the on-off valve 30. Is detected by the valve opening failure detection described in the above. FIG. 2 is a flowchart illustrating a first embodiment, which is a basic operation of the above-described intake system evaporation leak prevention device abnormality determination. This operation is performed as a routine executed by the ECU 40 at regular intervals.

When the operation starts in FIG. 2, it is determined in step 201 whether or not the main switch is currently on. If the main switch is off, the value of the flag XSO is reset to 0 in step 203. Is done. The flag XSO will be described later. Step 2
If the engine main switch is ON at 01, it is next determined at step 205 whether or not the engine is currently operating. When the engine is not running, that is, when the main switch of the engine is turned on and the open / closed state detection sensor 3
3 is functioning, the process proceeds to step 207, and it is determined whether or not the output SW of the open / closed state detection sensor 33 is currently turned on. If the SW is ON in step 207, the current open / close state sensor 33
Has detected that the valve is closed.
In step 9, the value of the flag XSO is set to 1, and the current operation is terminated.

The flag XSO is a flag indicating whether or not the output of the open / close state sensor 33 when the engine is stopped is normal. XSO = 1 indicates that the output of the sensor 33 when the engine is stopped is normal. . On the other hand, if the output switch of the sensor 33 is OFF in step 207, the on-off valve 30 is open even though the engine is stopped, or the contact of the sensor 33 is stuck in the OFF state, or 33 indicates that the wire is disconnected. For this reason,
In this case, the value of the flag XSO is kept at 0, and the routine proceeds to step 225, where the value of the abnormal parameter XF is set to 2, and the operation is terminated. The parameter XF is a variable representing an abnormal state of the intake system evaporation prevention device, and XF = 2
Indicates that the valve closing failure of the on-off valve 30 or the abnormality of the sensor 33 (fixed contact off or disconnection) has occurred. Note that the operations in steps 205, 207, and 225 are performed according to the above-described abnormality detection A.1. This is an operation corresponding to.

Next, if it is determined in step 205 that the engine is currently operating, the process proceeds to step 211, where it is determined whether the current engine intake flow rate Ga detected by the air flow meter 35 is smaller than a determination value A. . Here, the determination value A is
The leak detection of the on-off valve described above (abnormality detection C.)
This is the sum of the set flow rate of the on-off valve 30 and the leakage flow rate passing through the maximum allowable leakage of the on-off valve.

If Ga <A in step 211, the engine is currently operating at an intake flow rate smaller than the intake flow rate for detecting the presence / absence of leakage of the on-off valve. The process proceeds to step 213 to determine whether the current state is normal or not.
3 It is determined whether or not the output is off. If the output of the sensor 33 is off, then step 217 is executed.
Then, it is determined from the value of the flag XSO whether or not the open / closed state detection sensor 33 when the engine is stopped indicates a normal output.
That is, when XSO = 1, the open / closed state detection sensor 33 is ON when the engine is stopped, and is currently OFF, so it is considered that the sensor 33 is operating normally. For this reason, since the current off output of the open / closed state detection sensor is reliable, the fact that the output SW is off in step 213 indicates that the open / close valve 30 is actually open. That is, in this case, since the on-off valve 30 is actually opened at a small intake air flow rate (Ga <A), no poor opening occurs and the on-off valve 30 is operating normally.

That is, in this case, since it can be determined that both the sensor 33 and the on-off valve 30 are operating normally, the process proceeds from step 217 to 219, and the value of the abnormal parameter XF is set to 0. XF = 0 means that there is no abnormality in both the on-off valve 30 and the sensor 33, and the intake system evaporation leak prevention device is normal. On the other hand, if the output XF of the sensor 33 is on in step 213, the on-off valve 30 is in a state of being actually closed (that is, poor valve opening) or the on-off state detection sensor 33 is abnormal (contact on-state). Fixation) has occurred. Therefore, in this case, the process proceeds to step 215, where the value of the abnormal parameter XF is set to 1, and the current operation is terminated.
XF = 1 means that the opening / closing valve 30 is defectively opened during engine operation or an abnormality of the opening / closing state detection sensor (fixed contact ON state) has occurred (see Abnormality detection B. above).

If XSO ≠ 1 at step 217, the open / closed state detection sensor 3
Since it is confirmed that an abnormality (contact off state fixation or disconnection) has occurred in 3 (step 207), the process proceeds to step 225, where the value of the abnormality parameter XF is set to 2, and the operation is terminated. Next, if Ga ≧ A in step 211, the determination of the presence or absence of leakage of the on-off valve in step 221 and subsequent steps (abnormality detection C. described above) is performed. in this case,
In step 221, the output SW of the open / closed state detection sensor 33
Is determined to be OFF, and if the SW is OFF, the process proceeds to step 223, where it is determined whether the sensor 33 is normal when the engine is stopped based on the value of the flag XSO. If XSO ≠ 1, it is confirmed that an abnormality has already occurred in the open / closed state detection sensor 33 before the engine is started. In this case as well, the routine proceeds to step 225, and the value of the abnormality parameter XF is set to 2. Then, this operation ends.

If XSO = 1 in step 223, it means that the sensor 33 is normal and the on-off valve 30 is open. In this case, the on-off valve 3
It can be seen that an unacceptable leak has not occurred at 0, but since the operation is currently in a state where the intake air flow rate Ga is large, a relatively small leak or a slight valve opening failure has occurred in the on-off valve 30. However, there is a possibility that the on-off valve is open at the current intake flow rate. Therefore, it is not possible to determine that the intake-evaporation-leakage prevention device is normal only by the determination result in the state of Ga ≧ A. Therefore, in this case, the current operation is terminated while maintaining the value of the abnormal parameter XF without performing the normality determination.

On the other hand, if the output SW of the open / closed state detection sensor 33 has not been turned off in step 221, the process proceeds to step 227 to determine whether or not the sensor 33 has failed before the engine is started (XSO = 1 or not). No) is checked, and if an abnormality has occurred in the sensor 33, step 225 is executed.
To set the value of the abnormal parameter XF to 2. If XSO = 1 in step 227, it means that the on-off valve 30 is not opened even though a relatively large intake air flow is actually passing through the on-off valve 30 at present.
This means that the on-off valve 30 has a leak larger than A, or that the on-off state detection sensor has an abnormality (contact ON state fixation). Therefore, in this case, the routine proceeds to step 229, where the value of the abnormal parameter XF is set to 3, and the operation is terminated. XF = 3 means that an unacceptably large leak has occurred in the on-off valve 30 or an abnormality (fixed contact in the on-state) of the on-off state detection sensor 33 has occurred.

As described above, according to the present embodiment, based on the intake air flow rate during engine operation detected by the air flow meter 35 and the output of the open / closed state detection sensor 33 at that time, the abnormality of the intake system evaporative leakage prevention device is determined. The presence or absence and the type of abnormality can be easily detected. Next, a second embodiment of the present invention will be described. In the first embodiment, the basic operation of the abnormality detection has been described. However, as can be seen from the flowchart of FIG. 2, in the first embodiment, it can be determined that the intake system evaporation prevention device is normal (XF = 0) only when the intake flow rate is small (Ga <A). ) State only (FIG. 2, steps 211 to 21).
9) In other operating states, although the abnormality is determined, the normal determination of the intake system evaporation prevention device cannot be performed. Also,
Since the determination value A of the intake flow rate is the sum of the intake flow rate at which the on-off valve 30 opens and the maximum allowable leakage of the on-off valve, the flow rate is slightly larger than the intake flow rate during idle operation after the completion of engine warm-up. It is. For this reason, in order to determine the normality of the intake system evaporative leakage prevention device, the intake flow rate is extremely low (for example, about the intake flow rate during idling after warm-up is completed).
It is necessary to drive the engine with.

In general, the engine is provided with an idle-up device for increasing the idle speed to prevent the engine from stalling when operating auxiliary equipment such as an air conditioner or idling when using an electric load such as a heater or lighting. Have been.
For this reason, when the air conditioner and the electric load are used, the intake air flow rate increases in accordance with the increase in the idle speed, even during the idle operation, as compared with the normal idle operation.

For this reason, in the engine having the idle-up device, the intake air flow rate does not become lower than the above-mentioned determination value A even when the engine is in idle operation when the load is used, and there is little chance that the normal determination of the intake system evaporative leakage prevention device can be made. There is a problem. In the present embodiment, in order to prevent the above, when performing an abnormality determination of the intake system evaporation leak prevention device, the abnormality is determined after the load is forcibly stopped to stop the operation of the idle-up device. .

For example, the load on the air conditioner, the heater, etc. does not cause any problem even if the load is stopped at any time during the operation of the engine. From a point of view, it cannot be stopped during engine operation. Therefore, in the present embodiment, it is determined whether or not there is an abnormality in the intake system evaporative leakage prevention device in a state where only the predetermined auxiliary device, that is, the auxiliary device which does not cause a problem even when stopped during engine operation, is stopped. . As a result, even in an engine equipped with an idle-up device, it is possible to increase the chances of making a normal determination of the intake system evaporation prevention device.

FIG. 3 is a flowchart for explaining the abnormality determining operation of the present embodiment. This operation is executed by the ECU 40 at regular intervals. The operation of FIG. 3 is different from FIG. 2 only in that steps 301 to 307 and step 309 are added to the operation of FIG. 2, and the other operations are the same as the operations of FIG. Will be described.

In this operation, after resetting the flag XSO when the main switch is off (steps 201 and 203) and judging an abnormality before starting the engine (steps 205 and 207), the engine is started in step 301 during engine operation. Whether the warm-up has been completed (whether the engine coolant temperature is equal to or higher than a predetermined temperature), whether the engine is idling at step 303 (whether the throttle valve is fully closed) In step 305, it is determined whether the value of the low intake air flow rate abnormality determination end flag XGA is 0 or not.
Only when all of 03 through 305 are affirmatively determined, the routine proceeds to step 307, in which a predetermined auxiliary machine (an auxiliary machine which does not cause a problem even if it stops during engine operation) is stopped. As a result, the idle-up device is stopped in a state in which a load (for example, an electric load by turning on a headlight or the like) other than a predetermined auxiliary device is not operating, so that the engine intake flow rate decreases to a flow rate during normal idle operation. .

Then, in this state, it is determined at step 211 whether or not the intake flow rate Ga is Ga <A. Step 303
If any one or more of the conditions from step 305 to step 305 are not satisfied, the process directly proceeds to step 211 without stopping the auxiliary equipment. In step 211, Ga
When <A is satisfied, the value of the low intake air flow rate abnormality determination end flag XGA is set to 1 in step 309, and then the determination of the low intake air flow rate in step 213 and thereafter is performed.

The low intake flow rate abnormality determination end flag XGA is
This flag indicates whether the low intake flow rate abnormality determination (determination in Ga <A) has been performed once after the engine is started, and is set to 1 when the low intake flow rate abnormality determination is performed.
When the value of the flag XGA is set to 1, the condition of step 305 is not satisfied from the next execution of the operation, so that the stop of the auxiliary machine (step 307) is not executed, and the execution of step 307 forces the execution of the step 307. The operation of the stopped auxiliary equipment is restarted. That is, the flag XGA
Is a flag having a function of preventing the auxiliary machine from being stopped twice or more for abnormality determination after the engine is started.

As described above, in the present embodiment, when the idle-up operation by the operation of the auxiliary machine is performed, the operation of the auxiliary machine is stopped to determine the abnormality, thereby preventing the leakage of the intake system evaporation. It is possible to increase the chances of making a normal determination of the device. Next, a third embodiment of the abnormality detection operation of the present invention will be described.

In the above-described second embodiment, in order to increase the chances of making a normal determination of the intake system evaporation leak prevention device, a predetermined auxiliary machine is stopped during engine operation, and then an abnormality determination is made. However, as described above, the headlights of the vehicle cannot be stopped during engine operation. Therefore, in the present embodiment, the abnormality determination is performed by forcibly stopping the idle-up device while operating the auxiliary machine. in this case,
If the idle-up device is stopped while the auxiliary machine is operating during normal idle operation, the engine may stall due to the load of the auxiliary machine. Therefore, in the present embodiment, by stopping the idle-up during the fuel cut operation performed during the engine braking when the vehicle is decelerated during the engine operation, the abnormality determination at the time of the low intake flow rate is performed while operating the auxiliary machine. I have.

In the operation of the engine brake during vehicle deceleration,
The throttle valve is fully closed, fuel cut is normally performed, and fuel supply to the engine is stopped. For this reason, during the fuel cut operation, the engine and the auxiliary equipment driven by the engine are driven by external force. In this embodiment,
If the engine is in fuel cut operation,
The abnormality determination is performed after the idle-up device is forcibly stopped. For example, an idle-up device normally operates when the throttle valve is fully closed during idle-up operation (idle operation).
The idle speed is increased by increasing the throttle valve opening. For this reason, by forcibly terminating the idle-up operation, the throttle valve is fully closed at the time of normal idling. During fuel cut operation, the engine speed is much higher than during normal idle operation, but when the throttle valve is fully closed, the intake air flow through the throttle valve is already choked, so the intake air flow is independent of the engine speed. Is equivalent to normal idle operation,
An abnormality can be determined at a low intake air flow rate.

FIG. 4 is a flowchart for explaining the abnormality determining operation of the present embodiment. This operation is performed by a routine executed by the ECU 40 at regular intervals. FIG.
2 is different from FIG. 2 only in that steps 401 to 409 and step 411 are added to the operation in FIG. 2, and the other operations are the same as those in FIG. 2. Therefore, only the differences will be described below. I do.

In the operation of FIG. 4, if the engine is currently running at step 205, it is determined at step 401 whether the engine warm-up is completed, and at step 403, whether the engine is currently running at the deceleration fuel cut operation. No, at step 405, whether the current engine speed NE is equal to or higher than a predetermined engine speed NE0,
In step 407, it is determined whether the value of the low intake flow rate determination end flag XGA is 0 or not, and only when all of the conditions in steps 401 to 407 are satisfied, step 4 is executed.
At 09, the idle-up device is forcibly stopped. As a result, the engine intake flow rate becomes a low intake flow rate corresponding to the idling operation while the operation of the auxiliary machine is continued, so that it is possible to determine the normality of the intake system evaporation leak prevention device.

The reason why it is determined in step 405 whether or not the engine speed is equal to or greater than a predetermined value NE0 (for example, NE0５００1500 RPM) is because the fuel cut operation is stopped when the engine speed becomes lower than NE0. It is. Also, in this embodiment, if the low intake flow rate abnormality determination is performed once, the value of the flag XGA is set to 1 in step 411, so that even when the fuel cut operation is being performed from the next operation execution, The stopping of the up device is not performed (step 407).

As described above, according to the present embodiment, it is possible to determine the normality of the intake system evaporative leakage prevention apparatus while operating the auxiliary equipment. I do.

[0063]

According to the first aspect of the present invention, it is possible to prevent the occurrence of an abnormality in the intake system evaporation leakage prevention device and improve the reliability of the device. Further, according to the inventions described in claims 2 to 6, it is possible to easily and reliably determine that an abnormality has occurred in the intake system evaporation prevention device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an intake system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a first example of an operation for determining an abnormality in an intake system evaporation leak prevention device;
It is a flowchart explaining embodiment of FIG.

FIG. 3 is a diagram illustrating a second operation of the abnormality determination operation of the intake system evaporation leak prevention device.
It is a flowchart explaining embodiment of FIG.

FIG. 4 is a third example of the operation of judging the abnormality of the intake system evaporation leak prevention device;
It is a flowchart explaining embodiment of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 ... Intake port 7 ... Intake passage 9 ... Throttle valve 10 ... Air cleaner 30 ... Open / close valve 33 ... Open / closed state detection sensor 35 ... Air flow meter 40 ... Electronic control unit (ECU)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 45/00 345 F02D 45/00 345K 364 364Q 366 366H F02M 35/10 311 F02M 35/10 311Z F term ( Reference) 3G084 BA05 BA13 CA03 CA06 DA27 EB22 FA00 FA07 3G093 BA12 CA03 CA04 CA08 CA12 CB07 DA00 DA09 DB24 EA05 EA09 EB00 FB02 3G301 JB02 JB09 KA05 KA07 KA10 KA16 KA26 LA03 MA24 PA00B PA01Z PF11Z

Claims (6)

[Claims] An engine is disposed in an intake passage of an internal combustion engine, and is closed when the engine is stopped to close the intake passage to prevent fuel vapor generated in the intake passage from leaking to the atmosphere and to be opened during engine operation. An intake system evaporation prevention device for an internal combustion engine having an on-off valve for allowing intake air to pass through an intake passage by way of a valve, wherein the on-off valve has a valve body having a planar sealing portion. The intake passage includes a planar sealing portion that comes into contact with a sealing portion of the valve body when the on-off valve is closed, and the sealing portion of the valve body and the intake passage when the on-off valve is closed. An intake passage for an internal combustion engine, wherein the intake passage is closed by surface contact with the sealing portion. 2. The on-off valve according to claim 1, wherein the on-off valve is closed when an intake flow rate passing through the intake passage is equal to or less than a predetermined set value, and is opened when the intake flow rate exceeds the set value. Open / closed state detecting means for detecting whether the valve is open or closed, intake flow rate detecting means for detecting an intake flow rate passing through the intake passage, and an intake flow rate detected by the intake flow rate detecting means during engine operation. 2. An intake system evaporative leakage prevention device according to claim 1, further comprising: abnormality determination means for determining whether or not the on-off valve is abnormal based on the on-off state of the on-off valve detected by the on-off state detection means. apparatus. 3. The intake air flow rate set value is set to a value smaller than the intake air amount during idle operation of the engine, and the abnormality determination means determines the predetermined intake air flow rate detected by the intake air flow rate detection means. When the on-off valve is in the closed state by the on-off state detecting means, it is determined that the on-off valve has leaked, and the determination value is an allowable maximum for the set value. The allowable maximum leak flow rate is set to a value obtained by adding the leak flow rate, and the allowable maximum leak flow rate is a leak amount at which the fuel vapor flow rate leaking from the intake passage to the atmosphere through the on-off valve at the time of closing the on-off valve becomes the maximum allowable value. 3. The intake system evaporative leakage prevention device according to claim 2, wherein when the engine is operated in a state in which the air flow has occurred in the on-off valve, the intake air flow rate is set to a value equal to the intake air flow passing through the leakage. 4. The abnormality judging means detects that the intake flow rate detected by the intake flow rate detecting means is smaller than the judgment value, and that the open / close valve is in an open state by the open / close state detecting means. 4. The intake-evaporation-leakage prevention device according to claim 3, wherein the on-off valve is determined to be normal at the time. 5. The engine according to claim 1, further comprising: an idle-up unit for performing an idle-up operation to increase an idle speed according to a load of an engine auxiliary machine during an idle operation. When the idle raising operation is performed by the means, after stopping the engine auxiliary machine, the intake flow rate detected by the intake flow rate detecting means and the open / closed state of the open / close valve detected by the open / closed state detecting means are changed to The air intake system leakage prevention device according to claim 4, wherein it is determined whether or not the on-off valve is normal. 6. The engine includes idle-up means for performing an idle-up operation for increasing an idle speed in accordance with a load on an engine accessory during idle operation, and the abnormality determination means further comprises an idle-up operation performed by the idle-up means. When the operation is being performed, the idle raising operation is forcibly stopped during a fuel cut operation in which the fuel supply to the engine is stopped when the engine is decelerated, and then the intake flow rate detected by the intake flow rate detection means and the opening / closing operation are performed. 5. The intake system evaporation prevention device according to claim 4, wherein it is determined whether or not the on-off valve is normal based on the on-off state of the on-off valve detected by a state detection unit. 6.