JPH05272415A - Evapopurge deterioration detecting device of engine - Google Patents

Abstract

PURPOSE:To prevent evaporation gas evaporated from the fuel tank of an engine from leaking in the atmosphere, and also regenerate activated carbon, especially, at the time of deterioration which is caused by accumulation of polymeric fuel on the activated carbon, by specifying deterioration factor of an evapopurge device, in relation to deteriorated detection of the evapopurge device having the canister for collecting evaporation gas. CONSTITUTION:The evapopurge deterioration detecting device of an engine is constructed in such a way as arranging a canister between the intake passage 2 of an engine 1 and a fuel tank 20, and having a control device 15 for closing an atmosphere intake passage opening/closing solenoid 12 and a trap passage opening/closing solenoid 6 when the regenerating means of an activated carbon 4 is judged necessary by detecting information of a ventitation resistance value found out from a pressure sensor 8 and a temperature sensor 9 and an activated carbon temperature difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents evaporative gases evaporating from a fuel tank of an engine from leaking to the atmosphere.
The present invention relates to a deterioration detecting device for evaporative purge having a canister for collecting evaporative gas.

[0002]

2. Description of the Related Art Conventionally, in such a deterioration detecting device, deterioration of an adsorbent for adsorbing evaporated fuel filled in a canister, and fine particles such as adsorbent crushed due to deterioration of the adsorbent Since the purge passage provided between the canister and the intake passage is clogged to make it difficult for the vaporized fuel to flow into or out of the canister, the fuel vaporized fuel leaks to the atmosphere. To solve this problem, for example, Japanese Utility Model Laid-Open No. 2-26754 is provided with a negative pressure sensor for detecting the ventilation state of the purge passage, and an abnormality for determining the occurrence of an evaporation purge abnormality according to the ventilation resistance of the purge passage. A disclosure regarding a detection device is provided. In addition, 3-35
In the 952 publication, a temperature sensor for detecting the temperature inside the canister is provided to compare the temperature difference between the maximum temperature inside the canister when the vehicle is stopped and the inside temperature of the canister when the vehicle is running with a predetermined temperature difference, When the temperature difference does not reach a predetermined temperature, there is disclosed an abnormality detection device which is a vaporized fuel collecting device including a canister and determines whether the evaporation purge is operating normally or abnormally.

[0003]

However, the above-mentioned abnormality detecting device cannot identify the following factors causing deterioration of the canister. That is, once the polymer gas composed of a hydrocarbon system having a relatively low volatility contained in the evaporated fuel is adsorbed on the adsorption surface of the adsorbent filled in the canister, the desorption of the polymer gas is carried out. Since the polymer gas once adsorbed on the adsorbent is accumulated and the adsorption capacity of the evaporated fuel decreases with time, the first evaporative purge deterioration factor and the second cause due to the crushing of the adsorbent Evaporative purge deterioration factor of No. 3 and the crushed particles crushed due to vibration and heat stress applied to the adsorbent block the adsorbent of the canister and prevent the inflow or outflow of evaporated fuel to the canister. Any of the deterioration factors of the evaporative purge and the canister is judged to be abnormal by the above-mentioned abnormality detecting device, and the above-mentioned three kinds of deterioration factors are not specified.

Regarding the above-mentioned deterioration factor of the evaporative purge, in particular, in the first deterioration factor of the evaporative purge, the polymer gas accumulated in the adsorbent is the cause of deterioration regardless of the deterioration of the adsorbent itself. It is possible to regenerate the adsorbent by evaporating the polymer gas from the adsorbent by heating or applying a negative pressure to the gas to boil it.
However, in the above-mentioned conventional technique, such a reproducible state is also regarded as deterioration, so that the evaporative purge deterioration factor is judged relatively early, and the life of the canister is estimated to be shorter than it actually is.

[0005]

According to the first to eighth aspects of the present invention, an engine evaporative emission deterioration detecting device is constructed as follows for the common purpose of solving the above problems.

According to the first aspect of the present invention, when the engine is stopped, the evaporated fuel generated from the fuel tank is adsorbed by the adsorbent filled in the canister, and the adsorbed fuel is adsorbed by the adsorbent during traveling of the vehicle. In the evaporative purge mechanism of the engine, which introduces the negative pressure in the intake passage into the combustion chamber of the engine through the intake passage to desorb and burn the vaporized fuel, regarding the vaporized fuel adsorbed by the adsorbent, The evaporative fuel is accumulated in the adsorbent and is provided with a detecting means relating to information on the accumulated state.

According to a second aspect of the present invention, the evaporated fuel generated from the fuel tank is adsorbed by the adsorbent filled in the canister when the engine is stopped, and the evaporated fuel adsorbed by the adsorbent during traveling of the vehicle, In the evaporative purge mechanism of the engine, which introduces the negative pressure in the intake passage into the combustion chamber of the engine through the intake passage to desorb and combust the evaporated fuel, the deterioration detecting means of the evaporative purge related to crushing of the adsorbent and the canister A device having a ventilation resistance detecting means for clogging.

According to a third aspect of the present invention, in the first aspect of the invention, there is provided ventilation resistance detecting means for the canister.
It has an adsorbent temperature detecting means and an adsorbent temperature difference detecting means which is a difference between the adsorbent temperature when the engine is stopped and the adsorbent temperature when the engine is operating, and the detected value of the ventilation resistance is less than a predetermined allowable value. If the detected value of the temperature difference of the adsorbent is less than the predetermined allowable value, it is determined that the cause of the deterioration of the evaporative purge is due to the accumulation of the evaporated fuel composed of a high molecular component in the adsorbent. Those that have means for determining factors.

According to a fourth aspect of the present invention, in the configuration of the second aspect, the ventilation resistance detecting means relating to the canister and the adsorbent which is the difference between the adsorbent temperature when the engine is stopped and the adsorbent temperature when the engine is operating. Having a temperature difference detecting means,
The detected value of ventilation resistance is more than a predetermined allowable value,
When the detected value of the adsorbent temperature difference is less than a predetermined allowable value, second evaporative purge deterioration factor determining means for determining that the deterioration factor of the evaporative purge is due to adsorbent crushing, and the detected value of the ventilation resistance is a predetermined allowable value. When the detected value of the adsorbent temperature difference is equal to or more than the value and is less than a predetermined allowable value, a third evaporation purge deterioration factor determination means for determining that the deterioration factor of the evaporation purge is due to the clogging of the evaporated fuel passage is provided. thing.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the first evaporative purge deterioration factor determining means causes the deterioration factor of the evaporative purge to be due to accumulation of evaporated fuel, which is a high molecular component, in the adsorbent. When it is determined that the adsorbent heating means for heating the adsorbent.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the deterioration factor of the evaporative purge is caused by the accumulation of the evaporated fuel, which is a polymer component, in the adsorbent by the first evaporative deterioration factor determining means. When it is determined, a high negative pressure applying means for applying a high negative pressure is provided in the canister filled with the adsorbent.

According to a seventh aspect of the present invention, in the first to sixth aspects, an air intake passage for introducing air into the canister and a trap passage for introducing evaporated fuel from the fuel tank are provided. A passage area control means is provided on each passage, and has a passage area control means shutting means for shutting off the communication of each passage as a high negative pressure giving means for giving a high negative pressure in the canister.

In the structure according to claim 8, in the structure according to claim 1, when the detected value of the ventilation resistance is less than a predetermined allowable value, the deterioration factor of the evaporation purge is due to the adsorbent of the evaporated fuel composed of a high molecular component. When the detected value of the ventilation resistance is equal to or higher than a predetermined allowable value, it is determined that the cause of deterioration of the evaporative purge is due to either adsorbent crushing or clogging of the vaporized fuel passage. 4. Equipped with evaporative purge deterioration factor determination means of 4.

[0014]

According to the structure of the present invention, the evaporated fuel scattered from the fuel tank is adsorbed by the adsorbent in the canister, and the fuel adsorbed by the adsorbent during traveling of the vehicle is
Negative pressure in the intake passage introduces it into the combustion chamber of the engine through the intake passage to desorb and burn the evaporated fuel. By detecting the accumulated state, it is possible to detect the deterioration of the adsorbent due to the evaporated fuel composed of a component having a high boiling point. According to the configuration described in claim 2, it is possible to detect the cause of deterioration of the evaporative purge due to crushing of the adsorbent or clogging of the canister.

According to the third aspect of the invention, when the ventilation resistance related to the canister and the temperature difference of the adsorbent are less than the respective allowable values, the adsorbent is not deteriorated without causing clogging of the canister. It has occurred,
By using a simple means, it is possible to identify that the cause of deterioration of the evaporative purge is deterioration of the adsorbent due to accumulation of evaporated fuel composed of a component having a high boiling point.

According to the structure of claim 4, each of the passage resistance of the vaporized fuel passage and the adsorbent temperature difference is compared with each allowable value, and the deterioration factor of the evaporation purge is adsorbed by a simple means. It is possible to specify whether the cause is crushing of the agent or the clogging of the canister.

According to the fifth aspect of the present invention, when the cause of the deterioration of the evaporative purge is due to the accumulation of the evaporated fuel, which is a component having a high boiling point, in the adsorbent, the adsorbent is overheated to evaporate the component having a high boiling point. Allows regeneration of the adsorbent by boiling off the fuel.

According to the sixth aspect of the present invention, when the cause of the deterioration of the evaporation purge is due to the accumulation of the evaporated fuel, which is a component with a high boiling point, in the adsorbent, a high negative pressure is introduced into the canister to reduce the boiling point. It makes it possible to regenerate the adsorbent by boiling the evaporated fuel composed of high components under reduced pressure.

According to the seventh aspect of the invention, as the high negative pressure applying means, the passage area control means blocking means for blocking the communication between the atmosphere suction passage and each of the trap passages is provided. A high negative pressure can be introduced, and the adsorbent can be regenerated using a simple means.

According to the eighth aspect of the present invention, when the ventilation resistance is less than the predetermined allowable value, the deterioration factor of the evaporation purge is caused by the accumulation of the vaporized fuel having a high boiling point component in the adsorbent, and the ventilation resistance is predetermined. When the value is equal to or more than the allowable value of, it is possible to determine that the deterioration factor of the evaporative purge is due to either crushing of the adsorbent or clogging of the evaporative fuel passage.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 7 is an explanatory view of the implementation of the evaporation purge device of the present invention. 1 is an engine, 2 is an intake passage, 3 is a canister, 4 is activated carbon, 5 is a trap passage, 6 is a solenoid for opening and closing the trap passage, 7 is a purge passage, 8 is a pressure sensor, 9 is a temperature sensor, and 10 is an atmosphere passage side. Partition, 11
Is a partition wall on the purge passage side, 12 is a solenoid for opening and closing the air intake passage, 13 is an air intake passage, 14 is a trap passage connecting pipe, 15 is a control device, 16 is an engine speed sensor, 1
7 is a throttle valve opening sensor, 18 is a throttle valve, 19 is a purge passage connecting pipe, 20 is a fuel tank, 2
Reference numeral 1 is a trap passage side partition wall, 22 is an intake passage pressure sensor, 23 is a canister heater, and 24 is a heater power supply device.

The canister 3 is provided in the middle of a connecting pipe connecting the downstream side of the throttle valve 18 of the intake passage 2 of the engine and the fuel tank 20.
And the canister 3 are communicated with each other through a purge passage connecting pipe 19, and the fuel tank 20 and the canister 3 are communicated with each other through a trap passage connecting pipe 14.

When the engine 1 is stopped, the fuel tank 20
A fuel vapor having a vapor pressure according to the ambient temperature is generated in the fuel inside, and the fuel vapor is trapped in the canister 3. The fuel vapor in the fuel tank 20 is guided to the trap passage 5 of the canister 3 via the trap passage connecting pipe 14.
After passing through the trap passage side partition wall 21, it is introduced into the canister 3 filled with the activated carbon 4. The activated carbon 4 is an adsorbent for adsorbing the fuel vapor, and the fuel vapor introduced into the canister 3 is adsorbed by the activated carbon 4.

When the engine 1 is in operation, the negative pressure in the intake passage 2 of the engine 1 is guided to the purge passage 7 through the purge passage connecting pipe 19, so that when the engine 1 is stopped, it is adsorbed and accumulated on the activated carbon 4. The purged fuel vapor is sent to the purge passage 7.
It is purged by the negative pressure inside and is desorbed from the activated carbon 4. The desorbed fuel vapor is supplied into the intake passage 2 through the purge passage 7 and the purge passage-side connecting pipe 19 and burned in the engine 1.

FIG. 8 shows an example of the measurement result of the temperature sensor 9 for measuring the temperature of the activated carbon 4 when adsorbing and desorbing the fuel vapor on the activated carbon 4. The fuel vapor accumulates on the activated carbon 4 with time, but since the activated carbon temperature during the adsorption of the fuel vapor shows a value according to the amount of the accumulated fuel vapor on the activated carbon 4,
As a result, the activated carbon temperature continues to increase with time. Further, the activated carbon temperature during the desorption of the fuel vapor continues to decrease with time according to the amount of the fuel vapor accumulated in the activated carbon 4, and when the desorption of the fuel vapor is completed, the activated carbon temperature is the minimum temperature. Is shown. That is, by utilizing the relationship between the activated carbon temperature and the amount of fuel vapor accumulated in the activated carbon 4, the activated carbon temperature difference which is the difference between the activated carbon temperature immediately after the engine is started and the activated carbon minimum temperature at the completion of desorption of the fuel vapor. Is detected and the activated carbon temperature difference becomes less than a predetermined temperature, it can be considered that the efficiency related to the adsorption or desorption of the fuel vapor from the activated carbon 4 becomes less than the predetermined efficiency.

Among the fuel vapors accumulated in the activated carbon 4, the high-molecular component fuel vapor has a high boiling point, so that it is accumulated over a long period of time with almost no evaporation due to vaporization. It accounts for most of the fuel vapor that accumulates in.

When the fuel vapor is processed by the evaporative purge device, if the fuel vapor passage communicating with the fuel vapor causes ventilation resistance due to clogging or the like, the flow rate of the fuel vapor flowing into or out of the canister 3 is limited. Therefore, there is a problem that the treatable fuel vapor capacity is reduced when the clogging is severe. That is, the pressure in the purge passage 7 is detected by the pressure sensor 8 provided in the purge passage,
From the pressure difference between the pressure in the intake passage 2 and the pressure in the purge passage 7, when the pressure difference is almost zero, it is due to an increase in ventilation resistance due to clogging on the activated carbon 4 side of the pressure sensor 8, and when the pressure difference is large. Intake passage 2 from pressure sensor 8
It is speculated that this is due to an increase in ventilation resistance due to clogging on the side.

In particular, when the activated carbon 4 in the canister 3 is deteriorated and activated carbon is crushed, the crushed activated carbon 4 causes clogging in each of the atmosphere passage side partition wall, the purge passage side partition wall, and the trap passage side partition wall. As a result, the ventilation resistance increases, and the efficiency related to the adsorption or desorption of the fuel vapor accompanying the crushing of the activated carbon 4 itself is reduced. Here, since the increase of the ventilation resistance and the reduction of the efficiency of the activated carbon 4 can be indirectly detected by the pressure sensor 8 and the temperature sensor 9, respectively, it is possible to identify the deterioration caused by the crushing of the activated carbon 4. Become.

From the above, the pressure sensor 8 and the temperature sensor 9
By detecting the purge passage pressure and the activated carbon temperature obtained from the above, it becomes possible to identify the deterioration factor of the evaporation purge device as shown in Table 1. FIG. 9 shows the result of identifying the deterioration factor of the evaporation purge device from the purge passage pressure and the activated carbon temperature. FIG. 10 is a flowchart showing the control of the evaporative purge apparatus in FIG.

At S1, the temperature difference between the activated carbon and the ventilation resistance of the canister are detected by the temperature sensor 8 and the pressure sensor 9. In S2, it is a determining means for determining whether the activated carbon temperature difference is less than a predetermined temperature difference. When the activated carbon temperature difference is equal to or more than the predetermined temperature difference, it is determined from FIG. Judging that any one of the jams has occurred, the process proceeds to S8. In S8, it is determined whether or not the ventilation resistance value is less than a predetermined value, and if the ventilation resistance value is greater than or equal to the predetermined value, the evaporative purge device is normal S9. If it is less than the predetermined value, the canister is clogged.
It is determined to be 10. Further, in S2, when the activated carbon temperature difference is less than the predetermined temperature difference, it is judged from FIG. 9 that the evaporative purge device has deteriorated the activated carbon due to the polymer gas, or has deteriorated the performance due to the activated carbon crushing, and thus proceeds to S3. move on. In S3, it is determined whether or not the ventilation resistance value is less than a predetermined value, and when it is equal to or more than the predetermined value, it is determined that S11 in which performance degradation due to crushing of activated carbon occurs. Further, in S3, when the ventilation resistance value is less than the predetermined value, it is determined that it is S4 in which the activated carbon is deteriorated by the polymer gas, and the process proceeds to S5. In step S5, the solenoid 12 for opening / closing the air intake passage and the solenoid 6 for opening / closing the trap passage are controlled to close the air intake passage 13 and the trap passage 5, respectively, so that the negative pressure in the intake passage 2 is reduced. It is possible to regenerate the activated carbon by introducing it into the canister 3 to give a high negative pressure to the canister 3 and to promote vaporization of the evaporated fuel accumulated in the activated carbon 4 by boiling under reduced pressure. In addition,
The activated carbon 4 is regenerated by forcibly heating the canister 3 using the canister heater 23, instead of the high negative pressure applying means using the atmosphere suction passage opening / closing solenoid 12 and the trap passage opening / closing solenoid 6. It is also possible to achieve Further, after the activated carbon temperature difference is detected again in S6, it is determined in S7 whether or not the activated carbon temperature difference has turned over a predetermined temperature difference. If the activated carbon temperature difference is less than the predetermined temperature difference, the process returns to S5 again. When the temperature difference of the activated carbon is equal to or more than the predetermined temperature difference, it is determined that the regeneration of the activated carbon 4 is finished, and the control is finished.

[Brief description of drawings]

FIG. 1 to FIG. 6 are claims correspondence diagrams relating to claims 3 to 8, respectively. FIG. 7 is a schematic diagram showing the structure of one device for carrying out the present invention. FIG. 8 is a graph showing the relationship between the activated carbon temperature and the elapsed time. FIG. 9 shows the identification result of the deterioration factor of the evaporative purge device from the purge passage pressure and the activated carbon temperature. FIG. 10 is a flowchart of the control device used in the present invention.

[Explanation of symbols]

1 ... Engine, 2 ... Intake passage, 3 ... Canister, 4 ... Activated carbon, 5 ... Trap passage, 6 ... Trap passage opening / closing solenoid, 7 ... Purge passage, 8 ... Pressure sensor, 9 ... Temperature sensor, 10 ... Atmosphere passage side Partition wall, 11 ... Purging passage side partition wall, 12 ... Atmosphere intake passage opening / closing solenoid, 13 ... Atmosphere intake passage, 14 ... Trap passage connecting pipe, 15 ... Control device, 16 ... Engine speed sensor, 17 ... Throttle valve opening sensor , 18 ... Throttle valve, 19 ... Purge passage connecting pipe, 20 ... Fuel tank, 21 ... Trap passage side partition wall, 22 ... Intake passage internal pressure sensor, 23 ... Canister heater, 24 ... Heater power supply device.

Claims (8)

[Claims] 1. When the engine is stopped, the evaporated fuel generated from the fuel tank is adsorbed by the adsorbent filled in the canister, and when the vehicle is running, the evaporated fuel adsorbed by the adsorbent is absorbed by the adsorbent.
In the evaporative purge mechanism of the engine, which introduces the negative pressure in the intake passage into the combustion chamber of the engine through the intake passage to desorb and burn the evaporated fuel, the evaporated fuel adsorbed by the adsorbent is An evaporative emission deterioration detection device for an engine, comprising detection means for detecting information relating to the accumulation state in which the evaporated fuel is accumulated in the adsorbent. 2. When the engine is stopped, the evaporated fuel generated from the fuel tank is adsorbed by the adsorbent filled in the canister, and when the vehicle is running, the evaporated fuel adsorbed by the adsorbent is
In the evaporative purge mechanism of the engine, which introduces the negative pressure in the intake passage into the combustion chamber of the engine through the intake passage to desorb and combust the evaporated fuel, the deterioration detection means of the evaporative purge related to adsorbent crushing and the canister related An evaporative emission deterioration detection device for an engine, comprising: a ventilation resistance detection means for clogging. 3. A ventilation resistance detecting means relating to a canister,
It has an adsorbent temperature detecting means and an adsorbent temperature difference detecting means for detecting a difference between the adsorbent temperature when the engine is stopped and the adsorbent temperature when the engine is operating, and the detected value of the ventilation resistance is less than a predetermined allowable value. When the detected value of the temperature difference of the adsorbent is less than the predetermined allowable value, the first evaporative purge that determines that the deterioration factor of the evaporative purge is due to the accumulation of the evaporated fuel composed of the high molecular component in the adsorbent The engine evaporative purge deterioration detection device according to claim 1, further comprising deterioration factor determination means. 4. A ventilation resistance detection means for detecting a ventilation resistance of a canister, and an adsorbent temperature difference detection means for detecting a difference between an adsorbent temperature when the engine is stopped and an adsorbent temperature when the engine is operating. When the value is equal to or larger than a predetermined allowable value and the detected value of the adsorbent temperature difference is less than the predetermined allowable value, a second evaporative purge deterioration factor determining means for determining that the deterioration factor of the evaporative purge is due to the crushing of the adsorbent. When the detected value of the ventilation resistance is equal to or greater than a predetermined allowable value and the detected value of the adsorbent temperature difference is less than the predetermined allowable value, it is determined that the deterioration factor of the evaporation purge is caused by the clogging of the fuel vapor passage. The evaporative emission deterioration detection device for an engine according to claim 2, further comprising a third evaporative emission deterioration factor determination means. 5. The adsorbent heating for heating the adsorbent when it is determined by the first evaporative purge deterioration factor determination means that the deterioration factor of the evaporative purge is due to the accumulation of the evaporated fuel consisting of a high molecular component in the adsorbent. The evaporative emission deterioration detection device for an engine according to claim 1, further comprising: 6. When the first evaporative purge deterioration factor determining means determines that the evaporative deterioration factor is due to the accumulation of evaporated fuel consisting of a high molecular component in the adsorbent, the inside of the canister filled with the adsorbent. 2. The engine evaporative purge deterioration detecting device according to claim 1, further comprising a high negative pressure applying means for applying a high negative pressure to the engine. 7. A passage area control means is provided on each of an atmosphere suction passage for introducing air into the canister and a trap passage for introducing evaporated fuel from the inside of the fuel tank, and a high negative pressure is provided in the canister. 7. The engine evaporative purge deterioration detection device according to claim 6, further comprising passage area control means shutting off means for shutting off the communication between the passages as the high negative pressure applying means. 8. When the detected value of the ventilation resistance is less than a predetermined allowable value, the deterioration factor of the evaporative purge is caused by the accumulation of the evaporated fuel consisting of a high molecular component in the adsorbent, and the detected value of the ventilation resistance is predetermined. 2. A fourth evaporation purge deterioration factor determination means for determining that the deterioration factor of the evaporation purge is caused by either the crushing of the adsorbent or the clogging of the evaporative fuel passage when the deterioration factor of the evaporation purge is equal to or more than the allowable value of. Evaporative Purge Degradation Detector for Engine.