JPH04143452A - Malfunction detector for evaporative purge system - Google Patents

Abstract

PURPOSE:To detect something wrong with an evaporative purge system so accurately by performing the redjugment of trouble after adsorbing a vapor to an adsorbent in a canister. CONSTITUTION:When a variation in both cases of purge gas content between before purge execution and during its execution is a specified value, namely, less than the value making an air-fuel ratio variation by a purge judgeable, any purge execution in once suspended. When vapor fuel out of a fuel tank 7 is normal, at a time when it ought to be sufficiently adsorbed to an adsorbent in a canister or a point of time when it is reached to pressure in the fuel tank 7, a trouble judgment by means of a trouble judging means 10 is made so as to be redone. Accordingly, when a purge system is abnormal, the trouble judgment can be done after having the vapor sufficiently adsorbed to the adsorbent in the canister. With this constitution, something wrong with the purge system is accurately detectable.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an abnormality detection device for an evaporative purge system.
In particular, a device that detects abnormalities in the evaporative purge system, which adsorbs evaporated fuel (vane gas) in an internal combustion engine to an adsorbent in a canister, and releases (purges) the adsorbed fuel into the fuel supply system for combustion under specified operating conditions. Regarding.

[Conventional technology]

In order to prevent the fuel (vapor) that evaporated inside the fuel tank from being released into the atmosphere, each part is sealed, and the vapor is once adsorbed to the adsorbent inside the canister, so that the fuel adsorbed while the vehicle is running is removed. In internal combustion engines equipped with an evaporative purge system that sucks vapor into the fuel supply system and burns it, if the vapor supply passage is damaged or the piping is disconnected for some reason, vapor will be released from the canister into the atmosphere. Further, if the purge passage to the fuel supply system is blocked, vapor in the canister overflows and leaks into the atmosphere from the canister atmosphere inlet. Therefore, it is necessary to detect the occurrence of such an abnormality in the evaporative purge system.

On the other hand, in an internal combustion engine equipped with an electronically controlled fuel injection control device, for example, the basic fuel injection time is calculated from the intake pipe negative pressure (absolute pressure) and the engine speed, and an oxygen concentration detection sensor installed in the engine exhaust passage is used. The engine is equipped with an air-fuel ratio feedback system that corrects the basic fuel injection time based on the output detection signal of the engine so that the air-fuel mixture supplied into the engine combustion chamber has a predetermined target air-fuel ratio. In this air-fuel ratio feedback system, the basic fuel injection time is multiplied by the air-fuel ratio feedback correction coefficient FAF obtained based on the output detection signal of the oxygen concentration detection sensor and other coefficients to correct the fuel injection time.

In an internal combustion engine equipped with such an air-fuel ratio feedback system, it has been known that when the evaporative purge system described above is executed, the air-fuel ratio feedback correction coefficient FAF changes depending on the purge gas concentration (for example, (See Japanese Patent Application Laid-open No. 186955/1983). Therefore, it is a good idea to take advantage of this to monitor the purge gas concentration flowing through the purge passage or the air-fuel ratio feedback correction coefficient FAF, and if these do not change even after running the evaporative purge system, determine that there is an abnormality in the evaporative purge system. It will be done.

[Problem to be solved by the invention]

However, with the above abnormality detection method for the evaporative purge system, if there is no vapor adsorbed to the adsorbent in the canister during engine operation, even if the evaporative purge is performed, there is no vapor adsorbed to the adsorbent in the canister. Since only air is sucked in, the purge gas concentration or air-fuel ratio feedback correction coefficient FAF hardly changes, resulting in a false detection of an abnormality in the evaporative purge system.Also, when the purge gas concentration is equal to the target air-fuel ratio, However, since the air-fuel ratio feedback correction coefficient FAF does not change, the above-described abnormality detection method incorrectly detects an abnormality in the evaporative purge system.

The present invention has been made in view of the above points, and an object of the present invention is to provide an abnormality detection device for an evaporative purge system that solves the above problems by performing evaporative purge with vapor adsorbed to an adsorbent in a canister. With the goal.

[Means to solve the problem]

FIG. 1 shows a basic configuration diagram of the present invention. In the present invention, after adsorbing the evaporated fuel from the fuel tank 7 to the adsorbent in the canister,
In an internal combustion engine 1 equipped with a purge execution means 8 that purges the adsorbed fuel into an intake passage 4, a concentration detection means 9 that substantially detects the purge gas concentration and a concentration detection unit 9 that detects the concentration before and after the purge execution means 8 executes the purge. The apparatus includes an abnormality determining means 10 that determines that a purge is abnormal when the change in purge gas concentration detected by the means 9 is less than a predetermined value, a purge execution interrupting means 11, and an abnormality warning means 12.

The purge execution interrupting means If temporarily interrupts the purge execution by the purge execution means 8 when the abnormality determining means 10 determines that the purge is abnormal. Further, the abnormality warning means 12 causes the abnormality determination means 10 to perform abnormality determination again after the purge execution interruption means 11 finishes interrupting the purge, and when the result is determined to be abnormal, it issues an abnormality warning.

[Effect]

In the present invention, when the change in the purge gas concentration before purge execution and the purge gas concentration during purge execution is less than a predetermined value (a value that allows determining the air-fuel ratio fluctuation due to normal purge), the purge execution is temporarily interrupted, and the fuel tank 7 The abnormality judgment by the abnormality judgment means 10 is made again at the time when the evaporated fuel (vane gas) reaches the time at which it should be sufficiently adsorbed by the adsorbent in the canister when it is normal, or when the fuel tank pressure (integral value) is reached. Therefore, when the purge system is normal, abnormality can be determined after the vapor is sufficiently absorbed by the adsorbent in the canister.

〔Example〕

FIG. 2 shows a system configuration diagram of an embodiment of the present invention. This embodiment is an example in which the internal combustion engine 1 is applied to a 4-cylinder, 4-cycle, spark ignition internal combustion engine, and is controlled by a microcomputer 21, which will be described later.

In FIG. 2, a surge tank 24 is provided downstream of the air cleaner 22 via a throttle valve 23. An intake temperature sensor 25 is installed near the air cleaner 22 to detect the intake air temperature, and the throttle valve 2
3 is attached with a throttle position sensor 26 that detects the opening degree (throttle opening degree) of the throttle valve 23 and the idle state. Also, surge tank 24
A diaphragm type vacuum sensor 27 is attached to.

The surge tank 24 is connected to the engine 30 via an intake manifold 28 corresponding to the intake passage 4 and an intake valve 29.
(corresponding to the internal combustion engine 1). A fuel injection valve 32 is disposed for each cylinder so that a portion thereof protrudes into the intake manifold 3θ, and fuel is injected into the air passing through the intake manifold 28 through this fuel injection valve 32.

The combustion chamber 31 includes an exhaust valve 33 and an exhaust manifold 3
It is connected to a catalyst device 35 via 4. Also, 36
is an ignition plug, which is provided so that a part thereof protrudes into the combustion chamber 31. Further, 37 is a piston that reciprocates in the vertical direction in the figure.

A distributor 38 distributes and supplies the high voltage generated by the igniter to the spark plugs 36 of each cylinder, and also detects the crank angle reference position and the crank angle from the rotation of the shaft.

A water temperature sensor 39 is provided so as to penetrate through the engine block 40 and partially protrude into the water jacket, and detects the temperature of engine cooling water and outputs a water temperature sensor signal. Furthermore, the oxygen concentration detection sensor (0! sensor) 41 is disposed so that a portion thereof protrudes through the exhaust manifold 34, and detects the oxygen concentration in the exhaust gas before entering the catalyst device 35. In addition, the exhaust temperature sensor 4
8 detects the catalyst temperature within the catalyst device 35.

Further, 42 is a fuel tank, which corresponds to the fuel tank 7 in FIG.
vapor) is delivered to the canister 44 via the vapor passage 43. The canister 44 is filled with an adsorbent such as activated carbon, and an air inlet 44a is provided at the bottom of the canister 44. The canister 44 also communicates with the intake pipe near the throttle valve 23 via a purge passage 45.

Note that the purge passage 45 may be communicated with the surge tank 24. Furthermore, a vacuum switching valve (VSV) 46 is provided in the middle of the purge passage 45, and its opening degree is adjusted by a control signal from the microcomputer 21, so that the air can be removed from the canister 44 to the intake pipe. Adjust the flow rate of purge gas to the The above vapor passage 43° canister 44. Purge passage 45 and VSV
46 constitutes the above-mentioned purge execution means 8 together with the microcomputer 21.

The vapor generated in the fuel tank 42 is transferred to the vapor passage 43.
The activated carbon in the canister 44 adsorbs the activated carbon through the canister 44 and prevents it from being released into the atmosphere. During operation, air is introduced from the atmosphere inlet 44a of the canister 44 using the negative pressure of the intake manifold 28, thereby desorbing the fuel adsorbed on the activated carbon, and the fuel flows through the purge passage 45 and vSV 46. It is sucked into the intake pipe through the air. Also,
The activated carbon is regenerated by the above desorption and is ready for the next vapor adsorption.

Further, 47 is a warning light, which together with the microcomputer 21 constitutes the abnormality warning means 12 described above. Also, 4
A pressure sensor 9 measures the internal pressure of the fuel tank 42.

The microcomputer 21 that controls the operation of each part of this configuration has a hardware configuration as shown in FIG. In the figure, the same components as those in FIG. 2 are denoted by the same reference numerals, and the explanation thereof will be omitted.

In FIG. 3, the microcomputer 21 includes a central processing unit (CPU) 50. Read-only memory (ROM) 51. Random access memory (RAM) used as a work area 52. Read-only memory (ROM) that stores processing programs. Backup RAM5 that retains data even after the engine is stopped
3. Input interface circuit 54. A/D converter 56 with multiplexer and input/output interface circuit 5
5, etc., and they are connected to each other via a bus 57.

The A/D converter 56 receives an intake temperature detection signal from the intake temperature sensor 25, a detection signal from the throttle position sensor 26, and an intake pipe negative pressure (PM) from the vacuum sensor 27.
detection signal, water temperature detection signal from water temperature sensor 38, 0. The oxygen concentration detection signal from the sensor 41 and the output detection signal from the pressure sensor 49 are sequentially switched and taken in through the input interface circuit 54, converted into analog/digital signals, and sequentially sent to the bus 57.

The input/output interface circuit 55 receives the detection signal from the throttle position sensor 26 and the distributor 38.
Rotation speed signals corresponding to the engine speed (NE) from the engine speed (NE) are input to the CPU 50 via the bus 57, while signals input from the bus 57 are sent to the fuel injection valve 32 and the VSV 46. and control them. Thereby, the fuel injection time TAU of the fuel injection valve 32 is controlled.

The CPU 50 in the microcomputer 21 having the above configuration executes the processing of the flowchart described below in accordance with the program stored in the ROM 51, and executes the processing of the concentration detection means 9 described above. Abnormality determination means 10, purge execution interruption means 11, etc. are realized.

FIG. 4 shows a schematic processing flowchart of the first embodiment of the present invention. The microcomputer 21 first determines whether or not the execution conditions are met for the abnormality detection process of the evaporative purge system (step 101), and if the execution conditions are not met, it ends this control, and if the execution conditions are met, it starts this control, and first Purging is performed in an idle state, and a tentative determination of abnormality is made (step 102). The reason why an abnormality is determined in the idle state is that the amount of intake air in the idle state is smaller than when the engine is running (the load range), so with the same purge amount, the value of the air-fuel ratio feedback correction coefficient used for abnormality determination This is because a large change can be obtained (the larger the load, the smaller the above change, which may make abnormality determination difficult).

Furthermore, if an abnormality determination is performed in a load range consisting of the following, there is a possibility that an erroneous determination will be made if the load or vehicle speed changes within the range during the abnormality determination.

The provisional determination of the above abnormality is made based on the amount of change in the air-fuel ratio feedback correction coefficient FAF, which will be described later, with and without purging (before and after). Here, air-fuel ratio (A/F) feedback control that is generally performed will be explained with reference to FIGS. 5 and 6. FIG. 5 shows an A/F realizing the air-fuel ratio control means 6.
When the feedback control routine is activated every 4 ms, for example, the microcomputer 21 first determines in step 201 whether or not the A/F feedback (F/B) condition is satisfied. When the F/B condition is not satisfied (for example, the cooling water temperature is below a predetermined value, the engine is starting, the amount is being increased after starting, the warm-up amount is being increased, the power is being increased, the fuel power is being increased, etc.), the air-fuel ratio feedback is performed. Correction factor FAF
The value of is set to 1.0 (step 201), and this routine ends (step 211). This performs oven loop control of the A/F.

On the other hand, when the F/B condition is satisfied (other than when the above F/B condition is not satisfied), the process advances to step 202, and 0. The detected voltage V1 of the sensor 41 is converted and taken in.

Next, in step 203, it is determined whether the air-fuel ratio is rich or lean by determining whether the detected voltage V1 is lower than the comparison voltage V□. When it is rich (Vl > Vll), it is determined whether the state has reversed from a lean state to a rich state (step 204).
, when the reversal is to rich, the value obtained by subtracting the skip constant R3L from the previous air-fuel ratio feedback correction coefficient FAFO is set as the new air-fuel ratio feedback correction coefficient FAF (step 205); on the other hand, the previous air-fuel ratio feedback correction coefficient is also in a rich state, If the richness continues, the integral constant Kl is subtracted from the previous FAF value to obtain a new FAFQ value (step 206), and this routine exits (step 211).

On the other hand, when it is determined to be lean in step 203 (V+
≦V1. ), it is determined whether the state has reversed from the rich state to lean (step 207), and if the state has reversed to lean, the skip constant R3R is calculated from the previous FAF value. The added value is set as the new air-fuel ratio feedback correction coefficient FAF (step 208). On the other hand, if the lean state was determined to be lean again last time, the integral constant KI is added to the FAF value and the new FAF value is set. (Step 209), and this routine ends (Step 211). Here, the skip constants R3L and R3R are set to values that are sufficiently larger than the integral constant KI.

As a result, when the air-fuel ratio changes as schematically shown in FIG. 6(A), the air-fuel ratio feedback correction coefficient FAF
As shown in Figure (B), when the air-fuel ratio changes from lean to rich, it is greatly attenuated by the skip constant R3L, changing the fuel injection time TAU to a smaller value, and the air-fuel ratio changes from rich to lean. When the fuel injection time TAU is reversed to , the skip constant R3R is greatly increased in a skip manner, thereby changing the fuel injection time TAU to a large value. Also, when the air-fuel ratio is the same, FAF increases to a large value when lean according to the integral constant (time constant) Kl, as shown in Figure 6 (B).
When rich, the value gradually changes to a smaller value.

This air-fuel ratio feedback correction coefficient FAF is multiplied by the basic fuel injection time determined by the engine speed and intake pipe negative pressure together with other coefficients to determine the final fuel injection time TAU. Control the fuel ratio.

Therefore, at the time of abnormality determination in step 103 of FIG. 4, the idle state (as schematically shown in FIG. 7(A))
is on), and when the VSV 46 is turned on (schematically shown in FIG. 7(B)) and purge is enabled, if the evaporative purge system is normal, the fuel adsorbed in the canister 44 will pass through the vSv 46 and the purge passage 45. Since the air-fuel mixture is purged into the intake passage, the intake air-fuel mixture shifts to the richer side than the target air-fuel ratio by the amount of purge.In order to correct this, the air-fuel ratio feedback correction coefficient FAF is set as shown in FIG. 7(C). It takes advantage of the change to the lean side (weight loss side).

Therefore, in step 103 of FIG. 4, the seventh
As shown in Figure (C), the air-fuel ratio feedback correction coefficient FA
When F changes to the lean side (reduction side), it is judged as normal,
If there is no change as shown in FIG. 7(D), or if there is a change to the rich side (increase side) as shown in FIG. 7(E), the evaporative purge system is determined to be abnormal.

If it is determined to be normal in step 103 of FIG. 4, the abnormality detection processing routine ends, and if it is determined to be abnormal, the process proceeds to the next step 104 in the same figure, and the purge is cut (execution of the evaporative purge is interrupted). Even if this purge cut is determined to be abnormal in step 103, the fuel adsorbed by the adsorbent in the canister 44 may have been purged normally during driving and the vapor may not have been adsorbed. , to ensure that the vapor is adsorbed by the adsorbent, is carried out continuously for a predetermined period of time or longer (step 10).
5).

After continuing the purge cut for a predetermined time, the canister 44
With the vapor adsorbed to the adsorbent inside, purge is performed in an idle state to determine an abnormality (step 106).
, performs an abnormality determination (step 107). The abnormality determination in step 107 is performed in the same manner as the abnormality determination in step 103, and if it is determined to be normal at this point, this abnormality detection processing routine is terminated. It is determined that there is an abnormality in the evaporative purge system, and the warning light 47 shown in FIG. 2 is turned on to notify the driver of the abnormality (step 108).

Next, the abnormality detection processing routine of the first embodiment of the present invention will be explained in detail with reference to FIGS. 8 and 9. In FIG. 8, first, the execution conditions are that the normal temporary determination flag A is not set (step 3o1), the engine cooling water temperature is, for example, 80°C or higher, and the engine has been warmed up (step 302).
), throttle position sensor (idle switch)
26 is on (step 303), and this abnormality detection routine execution completion flag B is not set (step 304).
), and furthermore, if the conditions that A/F feedback is being executed (step 305) are satisfied, step 3 is executed.
Proceeding to step 06, a tentative abnormality determination is made by the determination subroutine.

This determination subroutine is the routine shown in FIG. 9, in which the VSV 46 is first controlled to be turned off to cut the purge (Step 401), and the average value FAFOFF of the air-fuel ratio feedback correction coefficient FAF per unit time is calculated (Step 402). Then, the vSv 46 is turned on and the adsorbed fuel in the canister 44 is purged into the intake passage through the VSV 46 and the purge passage 45 (step 403), and in this state, the air-fuel ratio feedback correction coefficient FA per unit time is
The average value FAFON of F is calculated (step 404).

Finally, the two average values FAFOFF and F
The value of the difference from AFON is determined (step 405).

When the arithmetic processing by the above determination subroutine is completed, the process proceeds to step 307 in FIG. 8, and an abnormality determination is made as to whether or not the above value has deviated to the lean side (reduction side) by X% or more (step 103 in FIG. 4). ), if it deviates to the lean side by X% or more, it is determined to be normal and the process proceeds to step 319.
If it has not shifted to the lean side by more than X%, it is determined that there is an abnormality, and the process proceeds to step 308, where the VSV 46 is turned off and the purge is cut (corresponding to step 104 in FIG. 4).

Thereafter, the value of the temporary abnormality judgment flow flag is set to "l" (step 309), and the purge cut state is continued for a predetermined time of 7 minutes or more (step 310). When it is determined that the purge cut has been executed for the y amount, it is then determined whether the idle switch 26 is on (step 311);
It is determined whether A/F feedback is being executed (step 312), and if one of the conditions is not satisfied, the process advances to step 313, where the counter value C is incremented by "1", and the process returns to step 308, where the purge cut is further continued. On the other hand, if the conditions in steps 311 and 312 are both satisfied, the process advances to step 314 and the determination subroutine shown in FIG. 9 is executed.

Step 314 corresponds to the process of step 106 in FIG. It is determined whether or not there is a shift toward the lean side by X% or more (corresponding to step 107 in FIG. 4). If it is determined in step 315 that the shift is toward the lean side by X% or more, it is determined to be normal and the process proceeds to step 319. X%
If the deviation is not towards the lean side, it is determined that there is an abnormality and the counter value is incremented by "1" (step 316).
, it is determined whether the sum of the counter value C and the counter value C is 2 or more (step 317), and if it is less than 2, the process returns to step 308 to continue the purge cut.

When the above sum value is 2 or more, it is determined that the fuel adsorbed from the canister 44 has not been purged even after the maximum purge cut time of ZXy (minutes) has passed, and the microcomputer 21 determines that the fuel adsorbed from the canister 44 has not been purged. It is determined that there is an abnormality in the purge system, and the warning light 47 is turned on (
step 318). At that time, after clearing the flag A to "0", setting the flag B to "1", and clearing the counter values C and D (step 319), the normal
<- Return to the control (step 320) and end the process.

When flag B is set to "1", the next time the answer will be Yes in step 304 and this abnormality determination routine will end. It is sufficient if this determination is repeated during operation, which serves to prevent the purge cut time from increasing and affecting the recovery of the adsorption capacity of the canister. Note that flag B is cleared when the engine is started.

In this way, according to the present embodiment, an abnormality is determined based on the change in the air-fuel ratio feedback correction coefficient FAF before and after the evaporative purge, and when an abnormality occurs, the execution of the evaporative purge is interrupted for a predetermined period of time or longer, and then the above abnormality determination is made again. This greatly reduces false detections caused by fuel not being adsorbed by the adsorbent in the canister 44.Furthermore, since abnormality detection processing is performed in the idling state, abnormality detection is detected during driving. Abnormal pressure can be detected more accurately and stably than when detection processing is performed.

Next, a second embodiment of the present invention will be described. FIG. 10 shows a schematic processing flowchart of the second embodiment of the present invention. The microcomputer 21 first determines whether the execution conditions for abnormality detection have been met (step 501), and when the execution conditions have been met, executes the calculation for abnormality determination (step 502). This abnormality determination calculation is executed by the determination subroutine shown in FIG.
Obtain the difference between the F average value FAFOFF and FAFON when purge is on. However, in this embodiment, the abnormality detection process may be performed not only during the idle state but also during driving.

Next, it is determined whether the value of this difference deviates to the lean side by a predetermined value or more (step 503), and if it deviates to the lean side, it is determined to be normal and the abnormality detection processing routine ends. If it does not shift to the side, it is determined that there is an abnormality and the evaporative purge is interrupted by turning off the VSV 46 (step 504). Next, as shown in FIG. 2, a pressure sensor (P
It is determined whether the integrated value or integral value of the evaporated fuel pressure in the fuel tank 42 detected by the sensor) 49 from the time of purge cut is equal to or higher than a certain value (step 505).

Here, the output value of the pressure sensor 49 increases as the fuel temperature increases after the engine starts, as shown by the solid line ■ in FIG. Positive pressure results. Therefore,
In this embodiment, only the positive pressure portion of the output value of the pressure sensor 49 is integrated or integrated in step 505 of Fig. 1θ.
A value indicated by diagonal lines in the figure is calculated, and when this value reaches a predetermined value or more, it is determined that a required amount of vapor has been adsorbed to the adsorbent in the canister 44.

If it is determined in step 505 that the integrated value (or integral value) of the output value of the pressure sensor 49 has reached a predetermined value or more, the process proceeds to the next step 506, and the same abnormality determination calculation as in step 502 is performed. Thereafter, in the next step 507, the same abnormality determination as in step 503 is performed. If it is determined that there is an abnormality in step 507, the warning light 47 is turned on to notify the driver of the abnormality of the evaporative purge system (step 508), and if it is determined that the evaporative purge system is normal in step 507, this abnormality detection processing routine is ended. .

If the purge cut is simply continued for a predetermined period of time as in the first embodiment, it cannot be determined whether the required amount of vapor has been reliably adsorbed by the adsorbent in the canister 44, and the running conditions and temperature conditions during the purge cut period cannot be determined. , depending on the climate, vapor may be generated from the fuel tank 42 (for example, when the temperature is low, the fuel temperature is less likely to rise and vapor is less likely to be generated), and when the fuel amount is large or small, the fuel Since the amount of vapor generated also changes as the temperature rise changes, the required amount of vapor may not be adsorbed by the adsorbent in the canister 44. On the other hand, according to this embodiment, the integrated value (or integral value) of the output value of the pressure sensor 49
The amount of vapor adsorbed to the adsorbent can be determined more accurately.

Note that in each of the above embodiments, FAF is used as the concentration detection means 9 for determining abnormality of the evaporative purge system in view of the fact that the air-fuel ratio feedback correction coefficient FAF changes depending on the purge gas concentration. The point is that it is sufficient to detect changes in the purge gas concentration, and therefore, the present invention is not limited to the embodiments. For example, an HC sensor or the like may be provided in the middle of the purge passage 45 to directly detect the purge gas concentration.

〔Effect of the invention〕

As described above, according to the present invention, abnormality determination is performed again after vapor is adsorbed to the adsorbent in the canister, so abnormality in the evaporative purge system can be detected more accurately than in the past. It has features such as the ability to

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle configuration of the present invention, FIG. 2 is a system configuration diagram of an embodiment of the present invention, FIG. 3 is a diagram showing the hardware configuration of the microcomputer in FIG. 2, and FIG. 5 is a flowchart showing the A/F feedback control routine, FIG. 6 is a time chart for explaining the main parts of FIG. 5, and FIG. 4 is an explanatory diagram of the main parts, FIG. 8 is a flowchart showing the detailed processing routine of FIG. 4,
FIG. 9 is a flowchart showing the determination subroutine of the main part of FIG. 8, FIG. 10 is a flowchart showing a general abnormality detection processing routine of the second embodiment of the present invention, and FIG.
FIG. 2 is an explanatory diagram of the main part of FIG. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 2... Exhaust passage, 4... Intake passage, 7.42... Fuel tank, 8... Purge execution means, 9... Concentration detection means, 11... Purge execution interrupting means, 12... Abnormality warning means, 21... Microcomputer, 43... Purge passage, 44... Canister, 45... Vapor passage, 46... Vacuum
Switching valve (VSV), 49...pressure sensor. fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig.

Claims (1)

[Scope of Claims] An internal combustion engine comprising a purge means for adsorbing evaporated fuel from a fuel tank onto an adsorbent in a canister and then purging the adsorbed fuel into the intake passage, wherein the engine is purged by the purge means. Concentration detection means that substantially detects the gas concentration of the fuel, and a determination that a purge is abnormal when a change in the purge gas concentration detected by the concentration detection means is less than a predetermined value before and after purge execution by the purge execution means. an abnormality determination means for determining an abnormality; a purge execution interruption means for temporarily suspending the purge execution by the purge execution means when the abnormality determination means determines that there is an abnormality;
An abnormality detecting device for an evaporative purge system, characterized in that an abnormality detecting device for an evaporative purge system is provided, comprising abnormality warning means for causing the abnormality determining means to perform abnormality determination again and warning of an abnormality when an abnormality is determined.