JP5245928B2 - Evaporative fuel processor diagnostic device - Google Patents

Description

  The present invention relates to a diagnostic apparatus for a fuel vapor processing apparatus.

  With the drain cut valve fully closed and the purge valve opened, the intake pipe pressure downstream of the throttle valve is introduced into the flow path from the fuel tank to the purge valve. When the flow path pressure reaches the target pressure, the purge valve is fully closed. The flow path is closed and waits for the pressure of the flow path to rise by a predetermined value in this closed space state. In this process, the pressure of the flow path becomes the target pressure from the timing when the intake pipe pressure downstream of the throttle valve is introduced into the flow path. The pull-down time, which is the time until the timing when the flow path is reached, and the leak down time, which is the time from when the flow path is closed to the timing when the pressure of the flow path increases by a predetermined value, are sampled. There is one that diagnoses whether there is a leak in the flow path based on time (see Patent Document 1).

JP-A-7-305659

  By the way, a diagnosis permission condition consisting of a plurality of conditions is defined for the leak diagnosis, and if any one of the plurality of conditions is not satisfied after the diagnosis permission condition is satisfied, the diagnosis permission condition is not satisfied and the leak diagnosis is performed. Since it is canceled, it is desirable that the time required for leak diagnosis is short.

  In this case, if the upper limit of the purge valve opening and the rate of increase in opening when the intake pipe pressure downstream of the throttle valve is introduced into the flow path are set at a constant value, rich purge gas is supplied to the intake pipe downstream of the throttle valve. In order to avoid fluctuations in the air-fuel ratio, the upper limit of the purge valve opening and the opening increase rate when the intake pipe pressure downstream of the throttle valve is introduced into the flow path must be reduced.

  However, if the upper limit of the purge valve opening and the rate of increase in opening when the intake pipe pressure downstream of the intake throttle valve is introduced into the flow path are small, the time until the pressure in the flow path reaches the target pressure (pull-down time) As a result, the chances that the leak diagnosis will be canceled halfway will increase.

  In view of the above, an object of the present invention is to provide an apparatus that can reduce the chance that a leak diagnosis is canceled halfway.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

The present invention relates to a fuel tank (1), a canister (4) for adsorbing fuel vapor generated in the fuel tank (1), and fuel vapor generated in the fuel tank (1) to the canister (4). A first passage (2) for guiding, a second passage (6) communicating the canister (4) and the intake pipe (8) downstream of the throttle valve (7), and the second passage (6) The canister (4) is opened by opening and closing the purge valve (11) under the condition that the pressure of the intake pipe (8) downstream of the throttle valve (7) is lower than the atmospheric pressure during engine operation. In the evaporative fuel processing apparatus comprising the purge valve control means (21) for desorbing the fuel vapor adsorbed on the gas and supplying it as a purge gas to the intake pipe (8) downstream of the throttle valve (7), the canister (4) A drain cut valve (12) for opening and closing a passage for introducing air, and a pressure detection means (13) for detecting the pressure in the flow path (2, 6a) from the fuel tank (1) to the purge valve (11). And when the diagnosis permission condition is satisfied, close the drain cut valve (12) and open the purge valve (11) to introduce the intake pipe pressure downstream of the throttle valve (7) into the flow path (2, 6a), When the pressure of the flow path detected by the pressure detection means (13) reaches a target pressure, the purge valve (11) is fully closed and the flow path (2, 6a) is closed, and this closed space state And waits for the pressure of the flow path (2, 6a) detected by the pressure detection means (13) to rise by a predetermined value, and the intake pipe pressure downstream of the throttle valve (7) is changed to the flow path (2, 6a). Introduced in Thailand From the pull-down time, which is the time from when the pressure of the flow path (2, 6a) reaches the target pressure, to the timing at which the flow path (2, 6a) is closed, the flow path (2, 6a) ) And the leak down time that is the time until the pressure rises by a predetermined value, and based on the two sampled times, it is determined whether or not there is a leak in the flow path (2, 6a). At the same time, based on the air-fuel ratio of the purge gas supplied to the intake pipe (8) downstream of the throttle valve (7) when the intake pipe pressure downstream of the throttle valve (7) is introduced into the flow path (2, 6a). The upper limit of the purge valve opening when the intake pipe pressure downstream of the throttle valve (7) is introduced into the flow path (2, 6a) is set to the air-fuel ratio of the purge gas when the air-fuel ratio of the purge gas is relatively large. The purge valve is opened when the fuel temperature in the fuel tank (1) is higher than a predetermined value even when the diagnosis permission condition is satisfied. Set the upper limit of degrees to the minimum value.

According to the present invention, a fuel tank, a canister for adsorbing fuel vapor generated in the fuel tank, a first passage for guiding the fuel vapor generated in the tank to the canister, an intake pipe downstream of the canister and the throttle valve, And a purge valve that opens and closes the second passage, and the purge valve is opened under the condition that the pressure of the intake pipe downstream of the throttle valve is lower than the atmospheric pressure during engine operation. And a purge valve control means for desorbing the fuel vapor and supplying it as purge gas to the intake pipe downstream of the throttle valve, and a drain cut valve for opening and closing a passage for introducing fresh air into the canister, and a fuel tank And a flow path pressure detecting means for detecting the pressure of the flow path to the purge valve. The intake valve pressure downstream of the throttle valve is introduced into the flow path, and when the pressure of the flow path detected by the pressure detection means reaches the target pressure, the purge valve is fully closed and the flow path is opened. In this closed space state, the flow path pressure detected by the pressure detection means waits for a predetermined value to rise, and the flow path pressure is set to the target from the timing when the intake pipe pressure downstream of the throttle valve is introduced into the flow path. The pull-down time, which is the time until the pressure is reached, and the leak-down time, which is the time from when the flow path is closed to the timing when the pressure of the flow path increases by a predetermined value, are sampled. Based on the two times, it is determined whether or not there is a leak in the flow path, and a throttle is introduced when the intake pipe pressure downstream of the throttle valve is introduced into the flow path. Based on the air-fuel ratio of the purge gas supplied to the intake pipe downstream of the valve, the upper limit of the purge valve opening when the intake pipe pressure downstream of the throttle valve is introduced into the flow path is set to the air-fuel ratio controlled by the engine. When the air-fuel ratio of the purge gas having a small influence is relatively large (lean), the purge gas air-fuel ratio is set larger than when the air-fuel ratio of the purge gas is relatively small (rich) , and the diagnosis permission condition is satisfied. In the case where the fuel temperature in the fuel tank is higher than a predetermined value, the upper limit of the purge valve opening is set to the minimum value. Therefore, when the air-fuel ratio of the purge gas is relatively large (lean), the intake pipe pressure is It will be introduced to the flow path at once, the pull-down time will be shortened by that amount, the frequency of leak diagnosis will be stopped halfway, and the chance of ending leak diagnosis can be increased. Yes.

It is a schematic block diagram of the diagnostic apparatus of the evaporative fuel apparatus of 1st Embodiment of this invention. It is a timing chart for demonstrating the principle of leak diagnosis. It is a timing chart which shows the change of the channel pressure at the time of leak diagnosis of a 1st embodiment, the purge valve opening, and the drain cut valve state. It is a flowchart for demonstrating sampling of the pull-down time of 1st Embodiment, and leak down time. It is a characteristic view of the upper limit of the purge valve opening degree with respect to the purge gas air-fuel ratio of the first embodiment. It is a characteristic view of the purge valve opening increase rate with respect to the purge gas air-fuel ratio of the first embodiment. It is a flowchart for demonstrating sampling of the pull-down time of 2nd Embodiment, and a leak down time. FIG. 6 is a characteristic diagram of an engine operating point when the engine is operated from the lowest rotation speed to the highest rotation speed so that the fuel consumption is improved. It is a characteristic figure of the output torque upper limit of the motor with respect to motor rotation speed. It is a characteristic view of the upper limit correction value of the purge valve opening of the second embodiment. It is a characteristic view of the increase rate correction value of the purge valve opening of the second embodiment. It is a whole block diagram of the hybrid vehicle of 2nd Embodiment.

  FIG. 1 is a schematic configuration diagram of a diagnostic apparatus for an evaporative fuel apparatus according to an embodiment of the present invention. In FIG. 1, the evaporated fuel processing apparatus mainly includes a first passage 2, a canister 4, a second passage 6 (purge passage), and a purge valve 11.

  The fuel vapor (vapor) in the upper part of the fuel tank 1 is guided to the canister 4 through the first passage 2, and only the fuel particles (gasoline particles) are adsorbed by the activated carbon 4 a in the canister 4, and the remaining air is stored in the canister 4. It is discharged to the outside from the atmosphere opening 5 provided in the vertical lower part (shown in the upper part of the canister 4 in the figure).

  The canister 4 is communicated with an intake pipe 8 downstream of the throttle valve 7 through a second passage 6, and a normally closed purge valve 11 driven by a step motor is provided in the second passage 6. During engine operation, the pressure in the intake pipe 8 downstream of the throttle valve 7 (hereinafter simply referred to as “intake pipe pressure”) is lower than atmospheric pressure under certain conditions (for example, the low load range after the engine warm-up is completed). When the purge valve 11 is opened in response to a signal from the engine controller 21 under these conditions, fresh air is introduced into the canister 4 from the atmosphere opening 5 of the canister 4 due to the pressure difference between the intake pipe pressure and the atmospheric pressure. The fuel particles adsorbed by the activated carbon 4a are desorbed by the fresh air, and are supplied to the intake pipe 8 downstream of the throttle valve 7 through the second passage 6 together with the fresh air. When the mixed gas of the fuel particles desorbed from the activated carbon 4a and fresh air is defined as “purge gas”, the purge gas supplied to the intake pipe 8 downstream of the throttle valve 7 is supplied from the fuel injection valve 9 (fuel supply means). It is burned in the combustion chamber along with the injected fuel. The fuel in the fuel tank 1 is supplied to the fuel injection valve 9 through the fuel pipe 16 by the fuel supply pump 15.

  The second passage 6 includes a canister side passage 6a from the canister 4 to the purge valve 11 and an intake pipe side passage 6b from the purge valve 11 to the outlet of the intake pipe 8.

  On the other hand, a normally open drain cut valve 12 is provided at the atmosphere opening 5 of the canister 4. The drain cut valve 12 is required to be in a fully closed state at the time of leak diagnosis and to make the flow path from the purge valve 11 to the fuel tank 1 into a closed space. Hereinafter, the term “flow path” simply refers to the flow path from the purge valve 11 to the fuel tank 1.

  In addition, a pressure sensor 13 (pressure detection means) is provided in the canister side passage 6a, and the pressure sensor 13 outputs a voltage proportional to the pressure (absolute pressure) of the flow path that is closed at the time of leak diagnosis.

  An intake air amount signal from the air flow meter 24, a crank angle signal from the crank angle sensor 22, a cooling water temperature signal from the water temperature sensor 23, an air / fuel ratio signal from the air / fuel ratio sensor 25 on the upstream side of the catalyst, and a downstream side of the catalyst The engine controller 21 to which the oxygen concentration signal from the oxygen concentration sensor 26 is input controls the fuel injection from the fuel injection valve 9 and the ignition timing by the spark plug 10, and opens the purge valve 11 according to the operating conditions. Control the degree. Specifically, in the fuel injection control, the fuel injection amount from the fuel injection valve 9 is controlled so that the air-fuel ratio of the exhaust gas flowing through the three-way catalyst 18 falls within a window centered on the stoichiometric air-fuel ratio. Further, when the purge permission condition is satisfied, the purge valve opening is calculated according to the intake air amount, and the purge valve driving step motor is controlled so as to obtain the purge valve opening (see, for example, Japanese Patent Laid-Open No. 11-351081). ).

  Further, the engine controller 21 uses the purge valve 11, the drain cut valve 12, and the pressure sensor 13 when the diagnosis permission condition is satisfied to determine whether or not there is a leak in the flow path from the fuel tank 1 to the purge valve 11 (leakage). (Diagnosis) is performed while the engine is running. The frequency of leak diagnosis is about once in one operation.

  The leak diagnosis process includes a process (pull-down process) for setting the flow path from the fuel tank 1 to the purge valve 11 to a pressure state (target pressure) lower than the atmospheric pressure, and a flow path from the fuel tank 1 to the purge valve 11 immediately thereafter. And a process of waiting for the pressure in the flow path to increase by a predetermined value ΔP in the closed space state (leak down process), and the pressure of the flow path is changed from the timing when the intake pipe pressure is introduced into the flow path. Time until reaching the target pressure Pm (pull-down time) and time from timing when the flow path is closed space to timing when the pressure of the flow path is increased by a predetermined value ΔP with reference to the target pressure Pm (leak down time) And sampling. Based on the two sampled times, it is determined whether or not there is a leak in the flow path.

The principle of leak diagnosis will be described with reference to FIG. 2. The drain cut valve 12 is switched from fully open to fully closed at the timing t1 when the diagnosis permission condition is satisfied, and the purge valve 11 is opened to a predetermined opening, thereby The pipe pressure (pressure lower than atmospheric pressure) is led to the flow path (the first passage 2 and the second passage 6) from the fuel tank 1 to the purge valve 11, and the pressure in the flow passage is reduced to the target pressure Pm. After waiting, the time (pull-down time) t _P until the pressure of the flow path reaches the target pressure Pm from the timing t1 when the purge valve 11 starts to open is sampled. When the pressure of the flow path reaches the target pressure Pm, the purge valve 11 is fully closed to keep the flow path (2, 6a) from the fuel tank 1 to the purge valve 11 in a sealed state. Then, the pressure of the flow path (2, 6a) kept in a sealed state is monitored by the pressure sensor 13, waits until the pressure of the flow path increases by a predetermined value ΔP, and the flow path is started from the timing when the purge valve 11 is fully closed. The time (leak down time) t _L until the timing at which the pressure increases by the predetermined value ΔP is sampled. This completes the sampling of the two times, the pull-down time t _P and the leak-down time t _L , so that the drain cut valve 12 is returned from the fully closed state to the fully open state.

FIG. 2 shows the case where there is a leak (see the alternate long and short dash line) and the case where there is no leak or the case where the leak is small (see the solid line), and the target pressure Pm is delayed when there is a leak. Since the rise from the target pressure Pm is fast, the pull-down time t _P when there is a leak is relatively long, and the leak time t _L when there is a leak is relatively short. On the other hand, when there is no leak or when the leak is small, the target pressure Pm is reached quickly and the rise from the target pressure Pm is slow, so the pull-down time t _P when there is no leak or the leak is relatively short. In addition, when there is no leak or the leak is small, the leak time t _L becomes relatively long. Thus, the difference between the case where there is a leak and the case where there is no leak or the case where the leak is small appears in the pull-down time t _P and the leak-down time t _L. Therefore, for example, by comparing the time ratio t _L / t _P between the leak down time t _L and the pull-down time t _P and the determination value, if the time ratio t _L / t _P is less than the determination value, there is no leak or If the leak is small, and if the time ratio t _L / t _P exceeds the determination value, it can be determined that there is a leak. The leak can be diagnosed by looking at the pressure change after the flow path (2, 6a) is sealed.

  The leak diagnosis method is not limited to this. For example, the leak hole area AL may be further calculated based on the pull-down time and the leak-down time, and a diagnosis of whether or not there is a leak may be made by comparing the leak hole area AL with a predetermined value (Japanese Patent Laid-Open No. Hei. No. 7-305659).

  Now, in the current control, as shown in the third stage of FIG. 2, the purge valve opening is increased by a certain amount at every control cycle from the timing of t1, in order to introduce the intake pipe pressure into the flow path. When the purge valve opening increasing in this way reaches the upper limit of the purge valve opening, the purge valve opening is maintained at the upper limit. The amount of increase in the purge valve opening per control cycle is the “increase rate of the purge valve opening”, and the increase rate of the purge valve opening and the upper limit of the purge valve opening are set to a constant value. In this case, the increase rate of the purge valve opening and the upper limit of the purge valve opening are kept constant regardless of whether the fuel vapor adsorbed on the canister 4 is small or large, that is, regardless of the air-fuel ratio of the purge gas from the canister 4. If it is determined, it must be determined with a small value in consideration of the influence on the exhaust performance and the operation performance. That is, even for leak diagnosis, if the purge valve 11 is opened, purge gas from the canister 4 is supplied to the intake pipe 8 downstream of the throttle valve 7, so that rich purge gas is supplied to the intake pipe downstream of the throttle valve 7. 8, the air-fuel ratio of the combustion chamber gas tilts to a richer side than the stoichiometric air-fuel ratio, the combustion speed increases accordingly, the engine torque increases, and the torque before and after the supply of purge gas to the intake pipe 8 is increased. A step (torque shock) occurs. Alternatively, if the air-fuel ratio of the combustion chamber gas is tilted to the rich side with respect to the stoichiometric air-fuel ratio by supplying rich purge gas, the NOx conversion efficiency of the three-way catalyst 18 decreases. This is because in an engine provided with the three-way catalyst 18 in the exhaust passage 17, the fuel injection amount from the fuel injection valve 9 is feedback-controlled so that the air-fuel ratio of the exhaust gas passing through the three-way catalyst 18 fluctuates in the vicinity of the theoretical air-fuel ratio. However, since the feedback gain cannot be increased so much, it is not possible to cope with a sudden enrichment of the air-fuel ratio in which a rich purge gas is suddenly supplied. Therefore, the increase rate of the purge valve opening and the upper limit of the purge valve opening must be set to small values so as not to cause such a torque shock and a decrease in the conversion efficiency of the three-way catalyst 18.

  However, if lean purge gas is supplied to the intake pipe 8 downstream of the throttle valve 7, the air-fuel ratio of the combustion chamber gas does not lean to the rich side from the stoichiometric air-fuel ratio. If there is no torque step (torque shock) before and after the supply to the combustion chamber, and the air-fuel ratio of the combustion chamber gas does not tilt to the rich side from the stoichiometric air-fuel ratio, the NOx conversion efficiency of the three-way catalyst 18 will decrease. There is nothing.

  Therefore, the present inventor paid attention to the fact that the influence of the air-fuel ratio of the purge gas from the canister 4 on the air-fuel ratio of the combustion chamber gas is different, and the increase rate of the purge valve opening and the upper limit of the purge valve opening Based on the air-fuel ratio of the purge gas, when the air-fuel ratio of the purge gas is relatively large (in the case of lean purge gas), the purge gas is set larger than in the case where the air-fuel ratio of the purge gas is relatively small (in the case of rich purge gas).

  This will be specifically described with reference to FIG. FIG. 3 shows a model of how the pressure of the flow path (2, 6a), the purge valve opening, the diagnosis permission condition, and the state of the drain cut valve 12 change during leak diagnosis. Here, a case where the air-fuel ratio of the purge gas is relatively large is indicated by a solid line, and a case where the air-fuel ratio of the purge gas is relatively small is indicated by a dashed line.

  First, a case where the air-fuel ratio of the purge gas is relatively small will be described first. In FIG. 3, if the drain cut valve 12 is fully open and the purge permission condition is satisfied and the purge valve opening is controlled before t0, the flow path (2, 6a) is opened to the atmosphere at this time. ing. For this reason, the pressure in the flow path is the atmospheric pressure P0 (see the uppermost stage in FIG. 3).

  If the diagnosis permission condition is satisfied at the timing t0, the purge control is interrupted at the timing t0, the purge valve opening is once set to zero, and the flow path (2, 6a) is opened to the atmosphere. At this time, the pressure sensor 13 The flow path pressure detected by is sampled as the atmospheric pressure P0. Subsequently, introduction of the intake pipe pressure into the flow path is started at the timing t1. That is, the purge valve 11 is opened with an inclination determined by the rate of increase in the purge valve opening, and when the purge valve opening upper limit is reached, the purge valve opening upper limit is maintained. In this case, when the air-fuel ratio of the purge gas is relatively small, relatively small values are set as the purge valve opening increase rate and the purge valve opening upper limit. For this reason, the purge valve 11 is opened only slowly as shown by the one-dot chain line in the second stage of FIG. As a result, even if the purge gas is rich, only a small amount of purge gas is supplied to the intake pipe 8 downstream of the throttle valve 7, so that the air-fuel ratio of the combustion chamber gas is inclined to the rich side from the stoichiometric air-fuel ratio. Therefore, it is possible to avoid a situation in which the combustion speed increases, the engine torque increases, and a torque step (torque shock) occurs before and after the purge gas is supplied to the intake pipe 8. Alternatively, it is possible to prevent the NOx conversion efficiency of the three-way catalyst 18 from being lowered due to the air-fuel ratio of the combustion chamber gas being inclined to the richer side than the stoichiometric air-fuel ratio.

  On the other hand, when the air-fuel ratio of the purge gas is relatively large, relatively large values are set as the purge valve opening increase rate and the purge valve opening upper limit. Therefore, as indicated by a solid line in the second stage of FIG. 3, the purge valve 11 is opened with a steep slope and larger than when the air-fuel ratio of the purge gas is relatively small. As a result, the timing at which the pressure in the flow path reaches the target pressure Pm is advanced from t2 to t2 ', and the pull-down time can be shortened compared with the case where the air-fuel ratio of the purge gas is relatively small. If the pull-down time can be shortened, the timing for returning the drain cut valve 12 to full open is also accelerated from t3 to t3 ', so the time until the end of the diagnosis is shortened, and the leak diagnosis can be terminated early. In this case, even if a larger amount of purge gas is supplied to the intake pipe 8 downstream of the throttle valve 7, the fuel concentration of the purge gas is not high, so the air-fuel ratio of the combustion chamber gas is larger on the rich side than the stoichiometric air-fuel ratio. Therefore, the engine speed increases and the torque step (torque shock) does not occur before and after the purge gas is supplied to the intake pipe 8. Alternatively, the NOx conversion efficiency of the three-way catalyst 18 does not decrease due to the air-fuel ratio of the combustion chamber gas being inclined to the richer side than the stoichiometric air-fuel ratio.

This control performed by the engine controller 21 will be described in detail based on the flowchart of FIG. FIG. 4 shows an operation flow for sampling the pull-down time t _P and the leak-down time t _L. It is not executed at regular intervals.

  In step 1, it is determined whether or not the diagnosis permission condition is satisfied based on the fuel injection pulse width, the intake air amount, and the like. The diagnosis permission condition is that the supply of the purge gas to the intake pipe 8 is completed to some extent and that the intake pipe pressure smaller than the atmospheric pressure is obtained. When the diagnosis permission condition is not satisfied, the process waits as it is.

  If the diagnosis permission condition is satisfied, the process proceeds to step 2 and subsequent steps. Steps 2 and 3 are parts for pre-processing, Steps 4 to 9 are parts for pull-down processing, Steps 11 and 12 are parts for leak-down processing, and Steps 10 and 13 are parts for sampling time.

  In addition, since it is complicated to describe even when the diagnosis permission condition is not satisfied during the pull-down process or leak down process, FIG. 4 illustrates the case where the diagnosis permission condition is not satisfied during the pull-down process or leak down process. Not listed. Actually, the diagnosis including the pull-down process and the leak-down process is stopped when the diagnosis permission condition is not satisfied during the pull-down process and the leak-down process. For example, the operating condition for obtaining an intake pipe pressure smaller than atmospheric pressure is a low load condition in which the throttle valve 7 is closed. For this reason, even if the diagnosis permission condition is satisfied under the low load condition and the pull-down process is performed, the diagnosis permission condition is not satisfied if the high load condition is reached during the pull-down process. Diagnosis is stopped because the intake pipe pressure downstream of the throttle valve 7 approaches the atmospheric pressure under high load conditions, and the pressure in the flow path does not reach the target pressure. This is because it will not be suitable for this.

  In steps 2 and 3, the purge valve 11 is fully closed to open the flow path (2, 6a) to the atmosphere, and the flow path pressure P detected by the pressure sensor 13 at this time is sampled as the atmospheric pressure P0.

  In step 4, the drain cut valve 12 is switched from the fully open state to the fully closed state. After the drain cut valve 12 is fully closed, the fuel temperature detected by the fuel temperature sensor 27 provided in the fuel tank 1 is compared with a predetermined value in step 5. The predetermined value is a value for determining whether or not fuel evaporation is vigorously occurring in the fuel tank 1. When the fuel temperature exceeds a predetermined value, it is determined that fuel evaporation is vigorously occurring in the fuel tank 1, and the routine proceeds to step 7 where the purge valve opening increase rate and the purge valve opening upper limit are preliminarily adapted. Set the minimum value. In this way, the minimum value is set when the fuel evaporation in the fuel tank 1 is intense, and if the purge valve 11 is opened largely even for leak diagnosis, rich gas from the fuel tank 1 is generated. This is because it is supplied to the intake pipe 8 downstream of the throttle valve 7 together with the purge gas from the canister 4, and torque shock occurs due to the rich air-fuel ratio, or the NOx purification rate of the three-way catalyst 18 deteriorates.

  On the other hand, if the fuel temperature is equal to or lower than the predetermined value in step 5, it is determined that the fuel does not evaporate vigorously in the fuel tank 1, and the process proceeds to step 6 to determine the purge gas air-fuel ratio (estimated value) from FIG. The purge valve opening increase rate and the purge valve opening upper limit are calculated by searching a table with the contents of.

  As shown in FIGS. 5 and 6, when the air-fuel ratio of the purge gas is relatively large, the increase rate of the purge valve opening and the upper limit of the purge valve opening are made larger than when the air-fuel ratio of the purge gas is relatively small. . This is because, when the air-fuel ratio of the purge gas is relatively large, even if the purge valve 11 is opened with a large inclination (speed) and greatly opened, the influence on the air-fuel ratio is small, and therefore torque shock is less likely to occur.

A known technique (see Japanese Patent Laid-Open No. 11-351081) is used for estimating the air-fuel ratio of the purge gas. That is, in the state where the purge valve 11 is fully closed and purge is not performed, air-fuel ratio feedback control is performed to obtain an air-fuel ratio feedback correction coefficient α [nameless number], and an air-fuel ratio learning value is calculated based on the air-fuel ratio feedback correction coefficient α. LALPHA [nameless number] is updated. For example, the average value ALPHAV [anonymous number] of the air-fuel ratio feedback correction coefficient α is
ALPHAVE = (α1 + α2) / 2 (1)
However, the maximum value of the half cycle of α1: α waveform,
α2: the minimum value of the half cycle of the waveform of α,
The operation region using the engine speed Ne and the load (for example, the basic fuel injection pulse width Tp) as parameters is divided into a plurality of small regions, and an air-fuel ratio learning value is stored for each small region. Then, read out the air-fuel ratio learning value LALPHA in a small region to which the operating condition that obtained α1 and α2 on the right side of the above equation (1) belongs,
LALPHA = LALPHA + (ALPHAVE-1.0) × GAIN
... (2)
However, GAIN: Gain (value from 0 to 1),
The air-fuel ratio learned value LALPHA is updated by the following formula, and the updated air-fuel ratio learned value LALPHA is stored in the original small area. The air-fuel ratio learning value learning value is set so that LALPHA does not disappear even after the engine is stopped.

  If the air-fuel ratio learning value LALPHA for each small region is updated in this way, even if there is a manufacturing error or deterioration with time in the flow characteristics of the fuel injection valve 9 or the detection characteristics of the air flow meter 24, these manufacturing errors or time-lapses. The deterioration is absorbed by the air-fuel ratio learning value LALPHA. That is, at the stage where the air-fuel ratio learning value LALPHA for each small region has converged, the flow characteristics of the fuel injection valve 9 and the detection characteristics of the air flow meter 24 are the same as there are no manufacturing errors or deterioration over time, and the air-fuel ratio feedback correction coefficient The average value of ALPHAV settles at 1.0.

Thus, in the state where the average value ALPHAV of the air-fuel ratio feedback correction coefficient is settled to 1.0 during the air-fuel ratio feedback control, the purge valve 11 is opened and the purge gas from the canister 4 is supplied to the intake pipe 8 downstream of the throttle valve 7. Then, the air-fuel ratio of the air-fuel mixture in the combustion chamber changes due to the purge gas. For example, when the air-fuel ratio of the purge gas is smaller than the stoichiometric air-fuel ratio, that is, a gas richer than the stoichiometric air-fuel mixture is supplied as the purge gas to the intake pipe 8 downstream of the throttle valve 7, it is detected by the air-fuel ratio sensor 25. Since the air-fuel ratio fluctuates to a richer side than the stoichiometric air-fuel ratio, the average value ALPHAV of the air-fuel ratio feedback correction coefficient is shifted to a smaller side than 1.0 to return the air-fuel ratio swung to the rich air side to the theoretical air-fuel ratio side. To go. Therefore, if the purge gas is supplied to the intake pipe 8 downstream of the throttle valve 7 during the air-fuel ratio feedback control, the air-fuel ratio feedback correction coefficient α is calculated, and the average value ALPHAV of the air-fuel ratio feedback correction coefficient is obtained (however, While the purge gas is being supplied, the air-fuel ratio learning value LALPHA is not updated), and the air-fuel ratio of the purge gas can be estimated from the average value ALPHAV of the air-fuel ratio feedback correction coefficient. That is, from the intake air amount Qa, the engine speed Ne, the air-fuel ratio learning value LALPHA, the average value ALPHAVE of the air-fuel ratio feedback correction coefficient, and the fuel injection pulse width Ti, the air-fuel ratio AFREVP [anonymous number] of the purge gas is
AFREVP = (Qa × k2 / Ne) / ((LALPHA−ALPHAV) × Ti)
... (3)
Where k2 is a constant,
It can be calculated by the following formula. The denominator on the right side of equation (3) is the amount of fuel in the purge gas per cylinder, and the numerator on the right side of equation (3) is the amount of air per cylinder.

  In step 8, the purge valve 11 is opened (driven) using the purge valve opening increase rate set in step 5 or 4 and the purge valve opening upper limit. At the timing of starting the opening operation of the purge valve 11, the first timer is started. This first timer is for measuring the elapsed time since the purge valve 11 was opened.

In step 9, the flow path pressure P detected by the pressure sensor 13 is compared with the target pressure Pm. When the pressure P of the flow path exceeds the target pressure Pm, the process waits as it is. When the pressure P of the flow path becomes equal to or lower than the target pressure Pm, it is determined that the pressure P of the flow path has reached the target pressure Pm. The first timer value at the timing when the flow path pressure P becomes equal to or lower than the target pressure Pm is sampled as the pull-down time t _P.

  In order to end the pull-down process and shift to the leak-down process, the purge valve 11 is switched to the fully closed state in step 11. At the timing of starting the closing operation of the purge valve 11, the second timer is started. The second timer is for measuring the elapsed time since the purge valve 11 is fully closed.

  In step 12, the pressure difference PPL (= P0−P) between the flow path pressure P detected by the pressure sensor 13 and the atmospheric pressure P0 obtained in step 3 is compared with a predetermined value ΔP. While the differential pressure DPL is less than the predetermined value ΔP, the process waits as it is.

When the differential pressure DPL becomes greater than or equal to the predetermined value ΔP, it is determined that the flow path pressure P has increased by the predetermined value ΔP with reference to the target pressure Pm, and the routine proceeds to step 13 at a timing when the differential pressure DPL becomes greater than or equal to the predetermined value ΔP. The second timer value is sampled as the leak down time t _L.

This completes the sampling of the pull-down time t _P and the leak-down time t _L , so in step 14 the drain cut valve 12 is opened.

In a diagnostic routine (not shown), leakage diagnosis is performed to determine whether or not there is a leak in the flow path (2, 6a) using these two times t _P and t _L. This leak diagnosis may be a known method.

  Here, the effect of this embodiment is demonstrated.

According to the present embodiment (the invention according to claim 1), the fuel tank 1, the canister 4, the first passage 2, the second passage 6, the purge valve 11, and the intake pipe pressure during engine operation. Evaporation is provided with a purge valve control means (21) that opens the purge valve 11 under the condition that the pressure is lower than the atmospheric pressure to desorb the fuel vapor adsorbed on the canister 4 and supplies it to the intake pipe 8 downstream of the throttle valve as purge gas. The fuel processing apparatus includes a drain cut valve 12 and a pressure sensor 13 (pressure detection means). When the diagnosis permission condition is satisfied, the drain cut valve 12 is closed and the purge valve 11 is opened to set the intake pipe pressure to the flow path (2, 6a), the purge valve 11 is fully closed when the pressure in the flow path (2, 6a) detected by the pressure sensor 13 reaches the target pressure Pm. Then, the flow path is closed, and the flow of the flow path (2, 6a) detected by the pressure sensor 13 in this closed space state is waited for a predetermined value ΔP to rise (Steps 1, 2, 4, 8, 9, 11, and 12), a pull-down time t _P that is a time from when the intake pipe pressure is introduced into the flow path to when the pressure of the flow path (2, 6a) reaches the target pressure Pm, The leak down time t _L that is the time from the timing when the path (2, 6a) is closed to the timing when the pressure of the flow path increases by a predetermined value ΔP is sampled (see steps 10 and 13 in FIG. 4). Based on the two sampled times, it is determined whether or not there is a leak in the flow path (2, 6a), and is supplied to the intake pipe 8 downstream of the throttle valve 7 when introducing the intake pipe pressure into the flow path. Based on the purge gas air-fuel ratio The upper limit of the purge valve opening when introducing the intake pipe pressure into the flow path (2, 6a) is relatively large (lean) of the purge gas, and the influence on the air-fuel ratio controlled by the engine is If the air-fuel ratio of the purge gas is set to be larger than that when the air-fuel ratio of the purge gas is relatively small (rich) (see step 6 in FIG. 4 and FIG. 5), the air-fuel ratio of the purge gas is relatively large (lean). In addition, the intake pipe pressure is introduced into the flow path at once, and the pull-down time is shortened accordingly. When the pull-down time is shortened, the time until the leak diagnosis is completed is shortened. As a result, it is possible to reduce the frequency with which the leak diagnosis is stopped halfway, and to increase the chance of ending the leak diagnosis.

  When the air-fuel ratio of the purge gas is relatively large (lean) and the influence on the air-fuel ratio controlled by the engine is small, the purge valve opening increase rate is higher than when the air-fuel ratio of the purge gas is relatively small (rich) Even when the purge valve 11 is increased, the change in the air-fuel ratio of the purge gas before and after opening the purge valve 11 does not increase. Correspondingly, according to the present embodiment (the invention described in claim 2), when the purge valve opening is increased at a predetermined increase rate when the intake pipe pressure is introduced into the flow path, the purge valve opening Is increased when the air-fuel ratio of the purge gas is relatively large (lean) and the influence on the air-fuel ratio controlled by the engine is small, compared to when the air-fuel ratio of the purge gas is relatively small. (Refer to step 6 in FIG. 4 and FIG. 6), even when the purge valve opening is opened at a predetermined increase rate when the intake pipe pressure is introduced into the flow path, the intake pipe pressure is easily introduced into the flow path. The pull-down time can be shortened by minutes.

When the fuel temperature in the fuel tank 1 is a high temperature exceeding a predetermined value, a lot of fuel vapor is generated, and a gas containing a large amount of this fuel vapor is added to the purge gas from the canister 4 and downstream of the throttle valve 7 at the time of leak diagnosis. However, according to the present embodiment (the invention according to claim 1 ), when the diagnosis permission condition is satisfied, the torque fluctuation generated in the engine increases and the drivability is affected. However, when the fuel temperature in the fuel tank 1 is a high temperature exceeding a predetermined value, the upper limit of the purge valve opening is set to the minimum value (see steps 5 and 7 in FIG. 4). A large amount of fuel vapor is generated, and the amount of gas containing a large amount of fuel vapor supplied to the intake pipe 8 downstream of the throttle valve 7 is reduced, so that deterioration of operability can be prevented.

  FIG. 7 shows a second embodiment that replaces FIG. 4 of the first embodiment. The same steps as those in FIG. 4 are given the same step numbers.

  The first embodiment is directed to a vehicle having only the engine as a drive source, but the second embodiment is a case where a hybrid vehicle having the engine and the motor as drive sources is targeted.

  Here, an example of a hybrid vehicle will be briefly described with reference to FIG. In FIG. 12, the hybrid vehicle is a so-called one-motor / two-clutch hybrid vehicle 50 (which is a parallel system). That is, the one-motor / two-clutch hybrid vehicle 50 includes an engine 31 and a motor motor 51 (motor generator) as a driving source, a transmission 53 that transmits power from the driving source to driving wheels, an engine 31 and a motor 51. The first clutch 54 that can be connected and disconnected, and the second clutch 55 that can connect and disconnect the motor 51 and the transmission 53 are provided. More specifically, the engine rotation shaft 56 is connected to the motor rotation shaft 57 via the first clutch 54, and the motor rotation shaft 57 is connected to the input side rotation shaft 58 of the transmission 53. The input side rotation shaft 58 is connected to the output side rotation shaft 59 of the transmission 53 via the second clutch 55. The output-side rotary shaft 59 is connected to drive wheels 61 and 61 via a differential gear device 60.

  A signal from the accelerator sensor 81 that detects the amount of depression of the accelerator pedal, a signal from the vehicle speed sensor 82 that detects the vehicle speed of the vehicle, and a signal from the rotation speed sensor 83 that detects the rotation speed of the input side rotating shaft 58 of the transmission 53. Is input to the AT controller 71, and the connection / disconnection between the transmission 53 and the second clutch 55 is controlled. A motor controller 72 to which a signal from a rotation speed sensor 84 that detects the rotation speed of the motor rotation shaft 57 is input controls the motor 51 via an inverter 73. The first clutch controller 74 controls connection / disconnection of the first clutch 54.

  The engine controller 21, the AT controller 71, the motor controller 72, the first clutch controller 74, and the integrated controller 75 are in communication with each other through a CAN 76. The integrated controller 75 communicates with the four controllers 21, 71, 72, and 74 to control the hybrid vehicle so as to obtain driving according to the driving state of the vehicle. For example, when the vehicle starts running from the vehicle stop state, the engine 31 is not started, and the vehicle is driven by the motor 51 with the second clutch 55 engaged. On the other hand, when it is determined that the accelerator pedal is further depressed and the driver has requested acceleration while the motor 51 is traveling, the first clutch 54 is engaged and the engine 31 is started. Respond to driver acceleration demand by adding driving force. Further, when the vehicle is decelerated, the first clutch 54 is opened and the motor 51 is used as a generator to convert the power from the drive shaft (kinetic energy of the vehicle) into electric energy and collect it in the battery 77. In addition, so-called idle stop control that automatically stops the engine 31 regardless of the driver's intention when the engine automatic stop condition is satisfied, and automatically restarts the engine 31 when the engine restart condition is satisfied thereafter. Is also going.

  Now, FIG. 7 differs from FIG. 4 of the first embodiment only in steps 21 to 26, so these will be mainly described. However, the second embodiment is based on the premise that the engine 31 and the motor 51 are connected while the motor is running and the engine is running from the start of the pull-down process to the end of the leak-down process. This is because, as will be described later, the torque fluctuation generated in the engine 31 due to the supply of purge gas to the intake pipe 8 is absorbed by the torque margin of the motor 51.

  In step 21, the engine operating point during motor running and engine operation is moved to the side where the intake pipe pressure becomes smaller and fixed. For example, when the engine is operated from the lowest rotational speed to the highest rotational speed for the best fuel economy, the engine operating point determined from the engine load and the rotational speed is a curve that rises almost to the right as shown in FIG. To change. That is, the curve shown is the optimum fuel consumption line. In the hybrid vehicle 50, the engine is not operated in the entire rotational speed range, so it is used only for a part of the curve. However, if the engine operating point (engine operating point) at the time of leak diagnosis is now at point A Then, only at the time of leak diagnosis, the engine rotational speed (Na) at the point A is kept as it is, and the fuel consumption is slightly deteriorated, but it is shifted to the point B where the engine load becomes small and fixed. For that purpose, the throttle valve opening may be reduced corresponding to the load decrease from point A to point B. Due to the decrease in the throttle valve opening, the intake pipe pressure becomes smaller on the side away from the atmospheric pressure. The reason why the engine operating point is moved to the side where the intake pipe pressure becomes smaller is to shorten the pull-down time. That is, when the intake pipe pressure is reduced, the time until the pressure of the flow path reaches the target pressure, that is, the pull-down time is shortened.

  Step 22 is basically the same as step 6 in FIG. 4 of the first embodiment. However, in the second embodiment, the purge valve opening upper limit and the purge valve opening increase rate obtained in step 6 of FIG. 4 of the first embodiment are changed to the purge valve opening upper limit basic value and the purge valve opening increase rate basic value. The values obtained by correcting the purge valve opening upper limit basic value and purge valve opening increase rate basic value with correction values corresponding to the margin of the output torque of the motor 51 are calculated as the purge valve opening upper limit and the purge valve opening increase rate, respectively. .

  Specifically, in step 23, the output torque margin of the motor 51 is calculated from the torque generated by the current motor 51 during motor running and the maximum torque that can be output at the current motor rotation speed. This will be described. FIG. 9 is a characteristic diagram of the motor output torque upper limit (= maximum torque that can be output) with respect to the motor rotation speed. Assuming that the current motor operating point is at point C, the motor output torque upper limit for the motor rotation speed (Nc) at point C is the value at point D. The torque generated by the current motor 51 can be determined from the current value flowing through the motor 51 and the voltage value applied to the motor 51. The current motor rotation speed is detected by a rotation speed sensor 84. Therefore, the characteristics of the motor output torque upper limit with respect to the motor rotation speed shown in FIG. 9 are stored in advance as a table, and the table is retrieved from the current engine rotation speed detected by the rotation speed sensor 84. The upper limit (D point value) of the motor output torque at the current motor rotation speed (Nc) (that is, the maximum torque that can be output at the current rotation speed of the motor 51) can be obtained. By subtracting the motor output torque at the current motor operating point from the upper limit of the motor output torque with respect to the current motor rotation speed thus obtained, the output torque margin of the motor 51 at the current motor rotation speed is calculated. Can do.

  Here, the motor 51 having an output torque margin is equivalent to the ability of the motor 51 to absorb torque fluctuations that occur in the engine 31 when the engine 31 and the motor 51 are rotating (connected). . That is, even if a torque shock occurs in the engine 31 due to the supply of the purge gas to the intake pipe 8, the torque shock is absorbed by the motor 51, so that the driver does not feel the torque shock. In other words, since a torque shock can be generated in the engine 31 by the amount of the output torque margin of the motor 51, the purge valve opening upper limit and the purge valve opening increase rate are within the range of the motor 51 output torque margin. It becomes possible to correct to the side which becomes large. If the purge valve opening upper limit and the purge valve opening increase rate are corrected to become larger, the time (pull-down time) until the pressure of the flow path reaches the target pressure Pm is accelerated by the correction amount, and leak diagnosis Is shortened.

  In step 24, the correction value of the purge valve opening increase rate and the correction value of the upper limit of the purge valve opening are calculated by searching the tables having the contents shown in FIGS. 10 and 11 from the output torque margin of the motor 51 obtained in step 23. To do.

  As shown in FIGS. 10 and 11, the purge valve opening upper limit correction value and the purge valve opening increase rate correction value are 1.0 when the output torque margin is zero and the output torque margin is relatively large. In this case, the output torque margin is set to be larger than that when the output torque margin is relatively small. This is because, when the output torque margin is relatively large, the purge valve 11 is opened with a steeper slope and more greatly, so that the torque shock becomes larger than when the output torque margin is relatively small. This is because the torque shock can be absorbed by the motor 51 whose output torque margin is relatively large.

In step 25, the purge valve opening upper limit correction value and the purge valve opening increase rate correction value thus obtained are multiplied by the purge valve opening upper limit basic value and the purge valve opening increase rate basic value to obtain the purge valve opening upper limit basic value. , Purge valve opening increase rate, that is,
Purge valve opening upper limit = purge valve opening upper limit basic value
× Purge valve opening upper limit correction value
(4)
Purge valve opening increase rate = purge valve opening increase rate basic value
× Purge valve opening increase rate correction value
... (5)
It is calculated by the following formula.

Since sampling of two times (t _P , t _L ) is completed in step 13, when the drain cut valve 12 is returned to the fully opened state in step 14, the engine operating point is released in step 26 and the engine 31 is optimized. Return to driving on the fuel economy line.

  In the hybrid vehicle, when there is a margin in the output torque of the motor 51, even if torque fluctuation occurs in the engine 31 due to the supply of rich purge gas to the intake pipe 8, the motor 51 connected to the engine 31 causes the engine 31 to The generated torque fluctuation can be absorbed. This means that torque fluctuations can be generated in the engine 31 by an extra output torque margin of the motor 51. In response to this, according to the second embodiment (the invention according to claim 3), the motor 51 connected to and disconnected from the engine 31 and the means for transmitting the driving force of the motor 51 to the drive wheels 61 (53, 60), and when the engine 31 is running and the motor is running and the engine 31 and the motor 51 are connected, the output torque upper limit of the motor 51 (the motor 51 can output at the current rotational speed of the motor 51). When the output torque margin is calculated by subtracting the current output torque of the motor 51 from the maximum torque) and the purge valve opening upper limit is relatively large based on the calculated output torque margin Furthermore, since the output torque margin is corrected to be larger than when it is relatively small (see steps 23, 24, 25 and FIG. 10 in FIG. 7), supply of purge gas to the intake pipe 8 is performed. While suppressing the engine torque fluctuation by the air-fuel ratio variation due, purge valve opening limit can be increased, thereby further reducing the pulldown time.

  In the embodiment, based on the air-fuel ratio of the purge gas supplied to the intake pipe 8 downstream of the throttle valve 7 when introducing the intake pipe pressure into the flow path, the upper limit of the purge valve opening when introducing the intake pipe pressure into the flow path The purge valve opening increase rate is set to be larger when the air-fuel ratio of the purge gas is relatively larger than when the air-fuel ratio of the purge gas is relatively small, but the intake pipe pressure is introduced into the flow path. When the air-fuel ratio of the purge gas is relatively large, only the upper limit of the purge valve opening when the intake pipe pressure is introduced into the flow path is based on the air-fuel ratio of the purge gas supplied to the intake pipe 8 downstream of the throttle valve 7 In addition, it may be set larger than when the air-fuel ratio of the purge gas is relatively small.

  In the second embodiment, the case where the hybrid vehicle is a one-motor, two-clutch hybrid vehicle has been described. However, the present invention is not limited to this hybrid vehicle.

DESCRIPTION OF SYMBOLS 1 Fuel tank 2 1st channel | path 4 Canister 6 2nd channel | path 7 Throttle valve 8 Intake pipe 9 Fuel injection valve (fuel supply means)
11 Purge valve 12 Drain cut valve 13 Pressure sensor (pressure detection means)
21 Engine controller 31 Engine 50 Hybrid vehicle 51 Motor

Claims (5)

A fuel tank,
A canister that adsorbs fuel vapor generated in the fuel tank;
A first passage for guiding fuel vapor generated in the fuel tank to the canister;
A second passage communicating the canister and an intake pipe downstream of the throttle valve;
A purge valve for opening and closing the second passage;
By opening the purge valve under the condition that the pressure of the intake pipe downstream of the throttle valve is lower than the atmospheric pressure during engine operation, the fuel vapor adsorbed on the canister is desorbed and the intake pipe downstream of the throttle valve is used as purge gas. And a purge valve control means for supplying to the evaporative fuel processing apparatus,
A drain cut valve for opening and closing a passage for introducing fresh air into the canister;
Pressure detecting means for detecting the pressure in the flow path from the fuel tank to the purge valve;
When the diagnosis permission condition is satisfied, the drain cut valve is closed and the purge valve is opened to introduce the intake pipe pressure downstream of the throttle valve into the flow path, and the pressure of the flow path detected by the pressure detection means becomes the target pressure. A closed space generating means for waiting for the pressure of the flow path detected by the pressure detecting means to rise by a predetermined value in the closed space state when the purge valve is fully closed and the flow path is closed;
The pull-down time, which is the time from when the intake pipe pressure downstream of the throttle valve is introduced into the flow path to the timing when the pressure of the flow path reaches the target pressure, and the flow from the timing when the flow path is closed. A time sampling means for sampling a leak down time which is a time until the timing when the pressure of the road rises by a predetermined value;
Leak determination means for determining whether or not there is a leak in the flow path based on the two sampled times;
When the intake pipe pressure downstream of the throttle valve is introduced into the flow path, the intake pipe pressure downstream of the throttle valve is introduced into the flow path based on the air-fuel ratio of the purge gas supplied to the intake pipe downstream of the throttle valve. And an upper limit setting means for setting the upper limit of the purge valve opening when the purge gas air-fuel ratio is relatively large when the purge gas air-fuel ratio is relatively small ,
An evaporative fuel processing apparatus characterized in that the upper limit of the purge valve opening is set to a minimum value when the temperature of the fuel in the fuel tank exceeds a predetermined value even when the diagnosis permission condition is satisfied . Diagnostic device.   When increasing the purge valve opening at a predetermined increase rate when introducing the intake pipe pressure downstream of the throttle valve into the flow path, the increase rate of the purge valve opening is relatively determined by the air-fuel ratio of the purge gas. 2. The diagnostic apparatus for an evaporated fuel processing apparatus according to claim 1, wherein when the air-fuel ratio is larger, the purge gas is set to be larger than when the air-fuel ratio of the purge gas is relatively small. A fuel tank,
A canister that adsorbs fuel vapor generated in the fuel tank;
A first passage for guiding fuel vapor generated in the fuel tank to the canister;
A second passage communicating the canister and an intake pipe downstream of the throttle valve;
A purge valve for opening and closing the second passage;
By opening the purge valve under the condition that the pressure of the intake pipe downstream of the throttle valve is lower than the atmospheric pressure during engine operation, the fuel vapor adsorbed on the canister is desorbed and the intake pipe downstream of the throttle valve is used as purge gas. Purge valve control means for supplying to
In an evaporative fuel processing apparatus comprising:
A drain cut valve for opening and closing a passage for introducing fresh air into the canister;
Pressure detecting means for detecting the pressure in the flow path from the fuel tank to the purge valve;
When the diagnosis permission condition is satisfied, the drain cut valve is closed and the purge valve is opened to introduce the intake pipe pressure downstream of the throttle valve into the flow path, and the pressure of the flow path detected by the pressure detection means becomes the target pressure. A closed space generating means for waiting for the pressure of the flow path detected by the pressure detecting means to rise by a predetermined value in the closed space state when the purge valve is fully closed and the flow path is closed;
The pull-down time, which is the time from when the intake pipe pressure downstream of the throttle valve is introduced into the flow path to the timing when the pressure of the flow path reaches the target pressure, and the flow from the timing when the flow path is closed. A time sampling means for sampling a leak down time which is a time until the timing when the pressure of the road rises by a predetermined value;
Leak determination means for determining whether or not there is a leak in the flow path based on the two sampled times;
When the intake pipe pressure downstream of the throttle valve is introduced into the flow path, the intake pipe pressure downstream of the throttle valve is introduced into the flow path based on the air-fuel ratio of the purge gas supplied to the intake pipe downstream of the throttle valve. An upper limit setting means for setting the upper limit of the purge valve opening at the time when the air-fuel ratio of the purge gas is relatively large when the air-fuel ratio of the purge gas is relatively small,
A motor connected to and disconnected from the engine;
Means for transmitting the driving force of the motor to the drive wheels,
When the engine and the motor are connected while the engine is running and the motor is running, an output torque margin is obtained by subtracting the current output torque of the motor from the maximum torque that the motor can output at the current rotation speed of the motor. And the upper limit of the purge valve opening is larger on the basis of the calculated output torque margin when the output torque margin is relatively large than when the output torque margin is relatively small. diagnostic apparatus for evaporation fuel processor you and corrects the. When the engine and a motor in operation before the SL engine and during motor travel is connected, the output torque margin the motor by subtracting the current output torque of the motor from the output maximum possible torque at the current rotational speed of the motor And the increase rate of the purge valve opening is larger when the output torque margin is relatively large based on the calculated output torque margin than when the output torque margin is relatively small. The diagnostic apparatus for an evaporative fuel processing apparatus according to claim 3 , wherein the evaporative fuel processing apparatus is corrected to the side of the evaporative fuel processing apparatus. When the fuel temperature of the diagnosis permission condition is satisfied when a was also in the fuel tank of a high temperature exceeding a predetermined value, according to claim 3 or 4, characterized in that setting the upper limit of the purge valve opening to the minimum value The diagnostic apparatus of the evaporative fuel processing apparatus of description.

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