JPH10104114A - Leakage diagnostic apparatus in processing apparatus for evaporated fuel of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately diagnose a leakage in an evaporated fuel-processing apparatus without inviting a large cost increase. SOLUTION: The air from an air pump set so as to supply a secondary air to a discharge path is introduced into a closed process route of an evaporated fuel-processing apparatus at the operation start time at low temperatures for supplying the secondary air. The process route is consequently pressured (S1-S6). The area of a leaking hole is estimated based on a pressure decrease characteristic after the pressuring is stopped (S10, S11) and a volume of the process route estimated based on the pressuring time and the reached pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for diagnosing leaks in a fuel vapor treatment system for an engine, and more particularly to a device for adsorbing and trapping fuel vapor in a fuel tank to a canister.
The present invention relates to a device for diagnosing whether or not a leak (leakage) has occurred in a processing path of the evaporated fuel in an evaporated fuel processing device that performs processing by sucking the engine.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for diagnosing the occurrence of a leak in an evaporative fuel processing apparatus, a negative pressure or a positive pressure is applied to the evaporative fuel processing path while a processing path of the evaporative fuel is closed. There is a method of diagnosing the presence or absence of a leak based on the loss of the applied pressure (Japanese Patent Application Laid-Open No. 7-29436).
No. 8, etc.).

[0003]

When a positive pressure is applied (pressurized) to the processing path to perform a leak diagnosis, an air pump is required. The configuration in which an additional pump is added increases costs and may limit the capacity of the pump due to layout restrictions in the engine room. As a result, it takes time to pressurize the processing path. In some cases, the diagnosis time was prolonged.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in a leak diagnosis apparatus for performing a leak diagnosis by pressurizing a processing path, it is possible to pressurize the processing path in a single time while suppressing an increase in cost. The purpose is to be.
It is another object of the present invention to avoid a decrease in diagnostic accuracy due to the generation of fuel vapor.

[0005]

Therefore, according to the present invention, there is provided an evaporative fuel processing apparatus which is configured to suck and evaporate fuel in a fuel tank adsorbed and collected by a canister to an engine for processing. A diagnostic device,
It is configured as shown in FIG. In FIG. 1, a processing path closing unit closes a processing path of the evaporated fuel in the evaporated fuel processing apparatus.

[0006] The processing path pressurizing means feeds air from an air pump provided to supply secondary air to the exhaust passage into the processing path closed by the processing path closing means, and pressurizes the processing path. Here, the leak detecting means detects the presence or absence of a leak in the processing path based on the pressure in the processing path detected by the pressure detecting means when the pressure is applied by the processing path pressing means.

With this configuration, if the engine is provided with an air pump for supplying secondary air to the exhaust passage, the air pump can be diverted to pressurize the processing path of the evaporative fuel processing apparatus. There is no need to add a dedicated pump for diagnosis. Generally, an air pump for supplying the secondary air to the exhaust passage has a relatively large capacity, so that the air is supplied into the processing path simultaneously with the supply of the secondary air. However, it is possible to secure necessary and sufficient air.

According to the second aspect of the present invention, the processing path is closed by the processing path closing means under the operating condition of supplying the secondary air to the exhaust passage by the air pump,
The air from the air pump is supplied to an exhaust passage and guided into the closed processing path, so that the leak detection unit detects a leak. Since the supply of the secondary air to the exhaust passage is generally performed at a low temperature start, at this time, a configuration in which a part of the air from the air pump is branched and guided into the processing path to perform a leak diagnosis. In this case, the diagnosis is performed under the condition that the amount of the evaporated fuel is sufficiently small, and it is possible to avoid a decrease in the diagnostic accuracy due to the generation of the evaporated fuel during the diagnosis.

According to the third aspect of the present invention, the processing path closing means closes a purge valve interposed in a processing path from the canister to the engine, while the processing path pressurizing means closes the air from the air pump. Is introduced from the fresh air introduction port of the canister to pressurize the inside of the processing path. According to such a configuration, the air of the air pump is introduced into the processing path from the fresh air inlet of the canister. Therefore, it is not necessary to close the fresh air inlet of the canister to close the processing path. It is possible to pressurize the inside of the processing path with a simpler configuration than in a case where air from an air pump is introduced from the middle of a pipe that communicates with the air.

[0010] In addition, when the fuel vapor which is normally adsorbed and collected in the canister is sucked into the engine, the air from the air pump is sent from the fresh air inlet of the canister to promote desorption. It becomes possible. In the invention according to claim 4, the processing path closing means and the processing path pressurizing means are provided with a switching valve for switching between opening the fresh air inlet of the canister to the atmosphere and connecting to the air pump, The switching valve connects the fresh air introduction port and the air pump to simultaneously block the processing path and pressurize the processing path.

According to this configuration, after the supply of air from the air pump is cut off, the canister is released to the atmosphere, so that the pressurized pressure cannot be maintained. However, the leak diagnosis can be performed with a simple configuration. become. For example, in the case of a configuration in which air is introduced from the middle of the processing path between the canister and the purge valve, a drain cut valve that closes the fresh air inlet of the canister is required to close the processing path, and the air pump An air cut valve that shuts off the air supply path from
According to the configuration, the functions of the drain cut valve and the air cut valve can be realized only by the switching valve.

According to the fifth aspect of the present invention, the flow rate of the air fed from the air pump into the processing path is kept constant, and the leak detecting means reaches when the air from the air pump is fed and pressurized. The configuration is such that the leak hole diameter is estimated based on the correlation between the pressure and the pressurizing time when the ultimate pressure is obtained. According to this configuration, since the flow rate of the air sent into the processing path is constant, if there is no leak, the pressure will increase with a characteristic corresponding to the volume of the processing path, and if the volume of the processing path is constant. Assuming that the ascending characteristic becomes dull according to the leak hole diameter (see FIG. 7), the leak hole diameter can be easily estimated from the pressurization time and the pressure obtained during the pressurization time.

If the flow rate is secured so that the differential pressure across the orifice provided in the air supply passage from the air pump is equal to or higher than a predetermined value, and the air flowing through the orifice is in a sonic flow, the The flow rate can be controlled according to the opening area. In the invention according to claim 6, the air supply from the air pump to the processing path is kept constant while the air supply path from the air pump to the processing path is closed to supply the air. An air cut-off valve for shutting off, wherein the leak detection means sends the air from the air pump into the processing path and pressurizes the pressure, the ultimate pressure when the ultimate pressure is obtained, the processing time, While shutting off the supply of air from the air pump with the air cut valve while closing the path, the pressure reduction time until the pressure sampling time, based on the pressure at the time when the pressure reduction time has elapsed, the leak hole diameter It was configured to be estimated.

According to this configuration, the characteristic of decreasing the pressure confined in the processing path varies depending on the diameter of the leak hole and the volume of the processing path. Therefore, the leak hole diameter can be estimated from the above-described reduction characteristics (see FIG. 4). Here, the ultimate pressure within the pressurization time is also affected by the leak hole diameter, but when the leak hole diameter is large, it is determined that the ultimate pressure is abnormally low, and is excluded from the target of the hole diameter estimation. In the case where the leak hole diameter is relatively small, the leak hole diameter can be estimated from the decrease characteristic.

[0015]

According to the first aspect of the present invention, in an engine having an air pump for supplying secondary air to an exhaust passage, a leak diagnosis performed by pressurizing a processing path of an evaporative fuel processing apparatus is performed. There is an effect that the pressurization can be performed in a short time without using a dedicated pump.

According to the second aspect of the invention, there is an effect that a highly accurate diagnosis can be performed while avoiding a decrease in the diagnosis accuracy due to the generation of fuel vapor. According to the third aspect of the present invention, the processing path can be pressurized with a simple system configuration. According to the invention described in claim 4, there is an effect that the valve configuration can be simplified when the leak diagnosis is performed based only on the pressure in the pressurized state.

According to the fifth aspect of the invention, there is an effect that the leak hole diameter can be easily estimated based on the difference in the pressure rise characteristics. According to the invention described in claim 6, there is an effect that the leak hole diameter can be accurately estimated based on the pressure reduction characteristics after pressurization in consideration of the volume of the processing path.

[0018]

Embodiments of the present invention will be described below. FIG. 2 is a system configuration diagram showing an evaporative fuel processing apparatus for an engine according to the first embodiment. A fuel tank 2 for storing fuel supplied to an engine 1 and an evaporative fuel generated in the fuel tank 2 are adsorbed and captured. With the canister 3 to gather,
They are connected by an evaporative fuel passage 4.

In the middle of the evaporative fuel passage 4, a mechanical check valve 5 which opens and closes in accordance with the pressure difference between the front and rear and an electromagnetic check valve bypass valve 6 which opens and closes by energization control are interposed in parallel. . The fresh air inlet 3a of the canister 3 is provided with an electromagnetic drain cut valve 7 that is opened and closed by controlling the power supply.

On the other hand, the canister 3 and the intake passage 9 downstream of the throttle valve 8 are connected by a purge passage 10. In the middle of the purge passage 10, an electromagnetic purge cut valve which is opened and closed by energization control is provided. 11 are interposed.
The purge cut valve 11 and the drain cut valve 7
Is opened, suction negative pressure of the engine is introduced into the canister 3 through the purge passage 10, and desorbed from the canister 3 together with fresh air introduced into the canister 3 through the fresh air inlet 3a ( The purged evaporated fuel is supplied to the intake passage 9.
And is subjected to combustion in the engine 1 for processing.

The check valve bypass valve 6, drain cut valve 7, and purge cut valve 11 are energized and controlled by a control unit 12 incorporating a microcomputer. The control unit 12 includes an air flow meter 13 for detecting an intake air amount of the engine 1, a crank angle sensor 14 for detecting a crank angle of the engine 1, and a water temperature sensor for detecting a coolant temperature of the engine 1.
A detection signal from 15 or the like is input.

The control unit 12 controls the power supply to the purge cut valve 11 based on these detection signals to control the purge amount. Further, the control unit 12 has a function of performing a leak diagnosis in the processing path (evaporated fuel passage 4, canister 3, purge passage 10) of the evaporated fuel processing apparatus. A pressure sensor 16 (pressure detecting means) for detecting pressure in the processing path by guiding pressure from a purge passage 10 between the fuel cell and a purge cut valve 11, and a fuel temperature sensor for detecting fuel temperature 17 are provided. Then, the presence or absence of a leak is diagnosed based on the detection result of the pressure sensor 16 when the inside of the processing path is pressurized.

Here, the pressurization in the processing path is performed using an air pump. In the present embodiment, the air pump 18 provided for supplying the secondary air to the exhaust passage is used. Pressurize. That is, the cost is reduced by not providing a pump dedicated to diagnosis. The air pump 18 supplies secondary air for promoting an oxidation reaction of a catalyst (not shown) disposed in the exhaust passage. The air from the air pump 18 is supplied with a check valve (not shown) or the like. Is supplied to the exhaust passage on the upstream side of the catalyst via the.

Further, in order to pressurize the processing path, a branch air passage 20 branching and extending from a secondary air supply passage 19 for supplying air from an air pump 18 to an exhaust passage is provided. The purge passage 10 is connected between the canister 3 and the purge cut valve 11. The branch air passage 20 is provided with an air cut valve 21 for shutting off the supply of air and an orifice 22 for adjusting the flow rate.

The flow chart of FIG. 3 shows a state of the leak diagnosis by the control unit 12. First, in S1, the cooling water temperature at the time of starting is set to a predetermined temperature (for example,
40 ° C) or less. Here, when the cooling water temperature at the time of starting is equal to or lower than the predetermined temperature, the process proceeds to S2, in which the air pump 18 is driven for a predetermined time to supply the secondary air to the exhaust passage on the upstream side of the catalyst. On the other hand, if the cooling water temperature at the start exceeds the predetermined temperature, 2
Since the supply of the secondary air is not performed, the leak diagnosis using a part of the secondary air cannot be performed.

When the secondary air is supplied to the exhaust passage, the process proceeds to S3, where it is determined whether or not the fuel temperature at the time of starting is lower than a predetermined temperature (for example, 30 ° C.). Is satisfied, it is determined that the leak diagnosis condition is satisfied, and the process proceeds to S4. The determination in step S3 is for causing a leak diagnosis to be performed under the condition that almost no evaporative fuel is generated in the fuel tank 2, and for preventing the occurrence of the evaporative fuel from affecting the detection pressure and reducing the diagnostic accuracy. Things. Therefore, when the fuel temperature is high and the generation of the evaporated fuel is expected, the process proceeds to S16 to cancel the diagnosis.

If the determination in S3 is omitted and the starting is at a low water temperature where the secondary air is supplied, it is estimated that the fuel temperature is low and the influence of the evaporated fuel is sufficiently small, and the leak diagnosis is performed. It is good also as a structure to make it perform. In S4, the processing path is opened to the atmosphere by controlling the purge cut valve 11 to close, the drain cut valve 7 to open, and the air cut valve 21 to close. The check valve bypass valve 6 is kept open during diagnosis.

In S5, it is determined whether or not the pressure sensor 16 is normal by determining whether or not the pressure detected by the pressure sensor 16 is within a predetermined value range set near the atmospheric pressure. When there is no abnormality in the pressure sensor 16,
Proceeding to S6, the inside of the processing path is closed by closing the drain cut valve 7 (processing path closing means), and then the air cut valve 21 is opened to open the air pump 18 driven for supplying secondary air. Is introduced into the purge passage 10 to pressurize the inside of the processing path (processing path pressurizing means).

Since the air pump 18 supplies secondary air into the exhaust passage against exhaust pressure, a large capacity (for example, 250 to 350 l / h) is used. When the passage is pressurized to a target pressure P1 (about 10 mmHg), air passing through the orifice 22 can be used as a sonic flow so that a constant flow proportional to the opening area of the orifice 22 can flow. Can be set relatively large so that the time required to pressurize to the target pressure is sufficiently short.

In S7, it is determined whether the pressure in the processing path detected by the pressure sensor 16 has become equal to or higher than the target pressure P1, or whether the pressurization time has become equal to or longer than a preset maximum time Tmax. Note that the pressurization time indicates the elapsed time from when the air cut valve 21 is opened to start pressurization in the atmospheric pressure processing path. The pressure in the processing path is the target pressure P
When the pressure reaches 1 or the pressurization time reaches the maximum time Tmax, the process proceeds to S8.

When the pressurizing time reaches the maximum time Tmax and proceeds to S8, it is determined whether or not the pressure at the time of pressurizing for the maximum time Tmax is higher than a predetermined pressure (for example, half of the target pressure P1). However, if a sufficient pressure increase is not obtained even after pressurization for the maximum time Tmax, it is estimated that a leak hole having a relatively large diameter (area) is generated, and the flow proceeds to S14 to cause a leak. Make a diagnosis (leak detection means).

On the other hand, if the target pressure P1 is reached within the maximum time Tmax, or if the pressure at the maximum time Tmax is equal to or higher than a predetermined pressure (for example, half of the target pressure P1), the process proceeds to S9.
The air cut valve 21 is closed, and pressurization is stopped while maintaining the closed state. If the target pressure has not been reached,
The pressure when the air cut valve 21 is closed is set to P1, and the pressurizing time when the air cut valve 21 is closed is set to T1 (see FIG. 4).

In the next step S10, the time from when the air cut valve 21 is closed (hereinafter referred to as depressurization time) is the maximum time Tma.
It is determined whether the pressure has reached x2 or more, or whether the pressure in the processing path has decreased to the target pressure P2. When the decompression time reaches the maximum time Tmax2 or the pressure decreases to P2, S
When the pressure goes down to P2 before reaching the maximum time Tmax2, the pressure reduction time at the time when the pressure reaches P2 is set to T2, and if the pressure does not drop to P2 even after the maximum time Tmax2 has elapsed. , The actual pressure at the time when the maximum time Tmax2 has elapsed is set to P2 (see FIG. 4).

In S12, P1 (pressurized pressure), T1
Based on (pressurizing time), P2 (decompression pressure), and T2 (decompression time) (see FIG. 4), an estimation calculation of the leak hole area (diameter) is performed according to the following equation. Leak hole area = K × T1 / (T2-T1) × Orf × (P
1 ^1/2 -P2 ^1/2 ) / P1 where K is a coefficient for standardization, and Orf is the orifice 22
Shows the opening area. However, since the air flowing through the orifice 22 is made to be a sonic flow, the opening area O
rf substantially indicates a constant air flow rate during pressurization.

The characteristics of the pressure drop after the air supply is cut off are affected by the leak hole area and the volume of the processing path, and the volume L of the processing path has no leak hole. Where, L = T1 × Orf / P1 and the leak hole area is: leak hole area = K × volume L × (P1 ^1/2 −P2 ^1/2 ) /
(T2−T1) Therefore, the equation for calculating the leak hole area in S12 estimates the leak hole area based on the pressure-reducing characteristic in consideration of the effect of the volume L, and estimates the leak hole area with high accuracy. Is possible.

If there is a leak hole, this also affects the calculation for estimating the volume L. However, when a large leak hole is generated, the target of the calculation for estimating the leak hole area is determined in S8. , The estimation accuracy can be sufficiently and sufficiently secured by setting the coefficient K. When the leak hole area is estimated and calculated, in S13, the estimated leak hole area is changed to a reference area (for example, a diameter of 1).
It is determined whether or not the area is smaller than 0.7854 mm ² ), and if it is not smaller than the reference area, the process proceeds to S14, where the occurrence of a leak is determined.
Then, a determination is made that no leak has occurred (leak detecting means).

FIG. 5 is a system configuration diagram showing an evaporative fuel processing apparatus for an engine according to the second embodiment.
The same elements as those described above are denoted by the same reference numerals and description thereof will be omitted. FIG.
In the configuration shown in FIG. 3, a branch air passage 20 that is extended from a secondary air supply passage 19 for supplying air from an air pump 18 to an exhaust passage is introduced into a canister 3 through a switching solenoid valve 23. An orifice 22 is provided in the middle of the branch air passage 20.

The switching solenoid valve 23 switches between a state in which the fresh air inlet 3a is open to the atmosphere and a state in which the fresh air inlet 3a is connected to the air pump 18. The valve 23 controls the fresh air inlet 3a. By opening the air to the atmosphere, the supply of air from the air pump 18 is cut off, and the drain cut valve 7 and the air cut valve 21 shown in the first embodiment are not provided.

Therefore, when the supply of air from the air pump 18 is stopped to stop the pressurization, the canister 3 is released to the atmosphere, and the pressure drop after the stop of the pressurization as in the first embodiment. Can not be performed based on the leak diagnosis, but the system configuration is simplified. In a normal purge state, it is also possible to supply air from the air pump 18 to the canister 3 to promote purging. In order to promote such purging, air is supplied from the fresh air inlet 3a of the canister 3. The configuration to be introduced can also be applied to a system provided with a dedicated air pump.

The flow chart of FIG. 6 shows the state of the leak diagnosis in the second embodiment. In S21, it is determined whether or not the cooling water temperature at the time of starting is lower than a predetermined temperature (for example, 40 ° C.). Here, when the cooling water temperature at the time of starting is equal to or lower than the predetermined temperature, the process proceeds to S22, in which the air pump 18 is driven for a predetermined time to supply the secondary air to the exhaust passage on the upstream side of the catalyst. On the other hand, if the cooling water temperature at the start exceeds the predetermined temperature, the process proceeds to S35 to cancel the diagnosis.

When the secondary air is supplied to the exhaust passage, the process proceeds to S23, where it is determined whether or not the fuel temperature at the time of starting is lower than a predetermined temperature (for example, 30 ° C.). If so, it is determined that the leak diagnosis condition is satisfied, and the routine proceeds to S24. If the fuel temperature exceeds a predetermined temperature, the routine proceeds to S35 to cancel the diagnosis. In S24, the processing path is opened to the atmosphere by controlling the purge cut valve 11 to be closed and controlling the fresh air inlet 3a to be open to the atmosphere (interruption of air introduction) by the switching solenoid valve 23. To The check valve bypass valve 6 is kept open during diagnosis.

In step S25, it is determined whether the pressure detected by the pressure sensor 16 is within a predetermined value range set in the vicinity of the atmospheric pressure. If a value is indicated, the diagnosis is canceled.
If there is no abnormality in the pressure sensor 16, the process proceeds to S26, where the switching solenoid valve 23 is used to open the fresh air inlet 3a.
And the air pump 18, and the air from the air pump 18 driven to supply the secondary air is supplied to the fresh air inlet 3.
A is introduced into the processing path from a, and the inside of the closed processing path is pressurized.

In S27, it is determined whether the pressure in the processing path detected by the pressure sensor 16 has become equal to or more than the target pressure P1, or whether the pressurization time has become equal to or more than a preset maximum time Tmax. When the pressure in the processing path reaches the target pressure P1 or when the pressurization time reaches the maximum time Tmax, the pressure at that time is stored and stored, and then the process proceeds to S28, where the switching solenoid valve 23 controls the fresh air inlet 3a. To the atmosphere.

In the next step S29, it is determined whether or not the ultimate pressure obtained by pressurization has become equal to or higher than the target pressure P1, and if it has reached the target pressure P1, it is determined that there is no leak. To judge that there is no leak. On the other hand, the target pressure P
If it has not reached 1, the program proceeds to S30, where the maximum time Tma
x is equal to a predetermined pressure (for example, target pressure P1).
1/10) or more, and determines whether the maximum time Tmax
If a sufficient pressure rise is not obtained even if only the pressure is applied, it is estimated that a leak hole having a relatively large diameter (area) is generated, and the flow proceeds to S33 to diagnose the occurrence of a leak.

It should be noted that the pressure judgment in S30 is to be used as a target for estimating the leak hole area up to a lower pressure than the pressure judgment in S8 in the flowchart of FIG. This is because, in the case of the first embodiment of the flowchart of FIG. 3, the purpose of estimating the volume of the processing path from the correlation between the pressurization time and the ultimate pressure is that the allowable range of the leak hole is narrow. is there.

If it is determined in S30 that a pressure rise of a predetermined value or more has been obtained, the flow advances to S31 to refer to a table in which the correlation between the ultimate pressure and the leak hole diameter is stored in advance and correspond to the actual ultimate pressure. Find the leak hole diameter to be used. Also in the present embodiment, the flow rate obtained through the orifice 22 is controlled to be constant, and the pressure from the start of pressurization depends on the characteristic according to the leak hole diameter (area) as shown in FIG. Becomes
The equilibrium pressure decreases as the leak hole diameter increases. Therefore, the correlation between the pressure at the time of pressurization for the maximum time Tmax and the leak hole diameter is previously obtained and stored as a table, and the leak hole diameter is estimated from the pressure at the maximum time Tmax.

Here, as described above, the pressure rise at the time of pressurization varies depending on the volume of the processing path, but the table is set according to the characteristics under the reference volume. Since the volume changes depending on the remaining amount of the fuel tank, the table to be referred to may be switched based on the detection result of the remaining amount sensor. In S32, it is determined whether or not the leak hole diameter determined in S31 is 1 mm or more. Here, if the estimated leak hole diameter is 1 mm or more, the flow proceeds to S33 to determine the occurrence of a leak, and if the estimated leak hole diameter is smaller than 1 mm, the flow proceeds to S34 to determine the absence of a leak.

In the system configuration of the first embodiment, the leak diagnosis may be performed only by the pressure rise characteristic of the second embodiment. However, in the case of the first embodiment, even after the pressurization is stopped, the processing path is stopped. Since the inside can be closed, a more accurate diagnosis can be made by performing the leak diagnosis based on the pressure reduction characteristics as described above.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a leak diagnostic apparatus according to the first embodiment.

FIG. 2 is a system configuration diagram of a fuel vapor processing apparatus according to the first embodiment.

FIG. 3 is a flowchart illustrating leak diagnosis control according to the first embodiment.

FIG. 4 is a diagram showing a state of a pressure change at the time of leak diagnosis in the first embodiment.

FIG. 5 is a system configuration diagram of a fuel vapor processing apparatus according to a second embodiment.

FIG. 6 is a flowchart illustrating leak diagnosis control according to a second embodiment.

FIG. 7 is a diagram showing a state of a pressure change at the time of leak diagnosis in a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Fuel tank 3 Canister 4 Evaporation fuel passage 5 Check valve 6 Check valve bypass valve 7 Drain cut valve 8 Throttle valve 9 Intake passage 10 Purge passage 11 Purge cut valve 12 Control unit 16 Pressure sensor 18 Air pump 21 Air cut valve 22 Orifice 23 switching solenoid valve

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 37/00 F02M 37/00 J G01M 3/00 G01M 3/00 H

Claims (6)

[Claims] In an engine provided with an air pump for supplying secondary air to an exhaust passage, an evaporative fuel is configured to be sucked and collected by a canister and processed by being sucked by the engine. A leak diagnosis device in a fuel processing device, comprising: a processing path closing means for closing a processing path of evaporative fuel in the evaporative fuel processing apparatus; and air from the air pump in a processing path closed by the processing path closing means. Path pressurizing means for feeding and pressurizing, pressure detecting means for detecting a pressure in a processing path closed by the processing path closing means, and pressure detecting means when pressure is applied by the processing path pressurizing means And a leak detecting means for detecting the presence or absence of a leak in the processing path based on the pressure detected by the processing path. Leakage diagnosis apparatus in emissions of fuel vapor processing apparatus. 2. An operating condition in which secondary air is supplied to an exhaust passage by the air pump, a processing path is closed by the processing path closing means, and air from the air pump is supplied to the exhaust path and the processing path is closed. 2. The leak diagnosis apparatus according to claim 1, wherein the leak detection is performed by the leak detection means. 3. The processing path closing means closes a purge valve interposed in a processing path from the canister to an engine, and the processing path pressurizing means discharges air from the air pump to a new one of the canister. 3. The leak diagnosis apparatus for an evaporative fuel processing apparatus for an engine according to claim 1, wherein the pressure in the processing path is increased by being introduced from an air inlet. 4. The processing path closing means and the processing path pressurizing means are provided with a switching valve for switching between opening of a fresh air inlet of the canister to the atmosphere and connection to the air pump. 4. The leak diagnostic apparatus according to claim 3, wherein the processing path is closed and the processing path is pressurized simultaneously by connecting the fresh air inlet and the air pump. 5. A method according to claim 1, wherein the flow rate of air sent from said air pump into said processing path is kept constant, and said leak detecting means determines the ultimate pressure and the ultimate pressure when the air from said air pump is fed and pressurized. The leak diagnosis device according to any one of claims 1 to 4, wherein the leak hole diameter is estimated based on a correlation with the pressurization time at the time of obtaining. 6. An air for shutting off the supply of air by closing a flow passage of air from the air pump into the processing path while keeping a flow rate of air sent from the air pump into the processing path constant. A cut valve, wherein the leak detecting means sends the air from the air pump into the processing path and pressurizes the ultimate pressure, the pressurizing time when the ultimate pressure is obtained, and the processing path. Estimating the leak hole diameter based on the pressure at the time when the pressure reduction time elapses after the air supply from the air pump is shut off by the air cut valve with the air cut valve being closed and the pressure reduction time has elapsed. Claims 1 to
3. The leak diagnostic device in the fuel vapor treatment device for an engine according to any one of 3.