JPH0518325A - Self-diagnosis device for fuel vapor processing equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the self-diagnosis accuracy of the fuel processor that reduces the vapor of the fuel generated in the fuel tank to the engine intake system. When a vapor is generated in a fuel tank 20, it is adsorbed by an adsorbent 23 in a canister 22, and a solenoid valve 29 is opened under a predetermined engine operating condition to purge the throttle chamber 2. The diagnosis of the abnormality of the fuel vapor processing device 21 is performed when the pressure in the fuel tank 20 detected by the pressure sensor 31 is equal to or higher than a predetermined value. This allows
Since the diagnosis based on the temperature change detected by the adsorbent temperature sensor 30 can be performed under the condition that the vapor is generated and adsorbed to the adsorbent 23, the erroneous diagnosis when the vapor is not generated can be avoided and the diagnostic accuracy is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-diagnosis device in a fuel vapor processing device for a fuel tank.

[0002]

2. Description of the Related Art A conventional fuel vapor processing apparatus for a fuel tank is disclosed in, for example, Japanese Patent Publication No. 53-19729. This is the vapor in the fuel tank when the pressure in the fuel tank becomes positive pressure above a certain value.
(Fuel vapor) is introduced into the canister, the vapor is adsorbed by an adsorbent such as activated carbon filled in the canister, and the fuel adsorbed by the adsorbent is supplied to the engine through a purge passage. There is.

A diaphragm valve that opens and closes in accordance with a throttle negative pressure is interposed in the purge passage, and the diaphragm valve has an engine in a predetermined appropriate purge region where the throttle negative pressure is a predetermined value or more. Control to perform fuel purging (desorption) to. By the way, in the fuel vapor processing apparatus for the fuel tank as described above,
When it becomes impossible to perform a normal purging operation due to the occurrence of clogging or leakage of the purging passage,
It is necessary to diagnose this to ensure the reliability of the device.

For this reason, a method of diagnosing the apparatus by grasping the temperature change of the adsorbent such as activated carbon has been considered. That is, since the adsorbent such as activated carbon has a property that the temperature rises while adsorbing (charging) the fuel and decreases when desorbing (purging) the fuel. By detecting the temperature rise of the adsorbent in the non-purge region or the temperature drop in the purge region, the abnormality of the processing apparatus is diagnosed.

[0005]

However, in the method of making a diagnosis by only monitoring the change in the temperature of the adsorbent as described above, the case where the temperature does not drop during purging is due to a leak due to a failure of the purge pipe. However, there is a problem that it is not possible to identify whether the purge was started in a state where no vapor was adsorbed to the adsorbent (in this case, the processing device is normal).

The present invention has been made in view of the above-mentioned problems of the conventional diagnosis system, and an accurate diagnosis can be performed by starting the diagnosis after confirming that vapor is adsorbed on the adsorbent. An object of the present invention is to provide a self-diagnosis device for such a fuel vapor processing device.

[0007]

Therefore, as shown in FIG. 1, one of the self-diagnosis devices for a fuel vapor processing apparatus according to the present invention is the adsorption, in which the presence or absence of abnormality is detected by the adsorbent temperature detecting means. In a self-diagnosis device of a fuel vapor processing apparatus equipped with an abnormality diagnosing means for diagnosing based on the temperature of the agent, the tank internal pressure detecting means for detecting the pressure in the fuel tank, and the tank internal pressure detecting means are detected. And a diagnosis condition determining means for permitting the abnormality diagnosis means to start the abnormality diagnosis when the pressure is equal to or higher than a predetermined value.

As shown in FIG. 2, another embodiment of the self-diagnosis apparatus for a fuel vapor processing apparatus according to the present invention is that the temperature of the adsorbent, which is also detected by the adsorbent temperature detecting means, for the presence or absence of abnormality. In a self-diagnosis device for a fuel vapor processing apparatus, which comprises an abnormality diagnosis means for diagnosing based on the above, a fuel temperature detection means for detecting a fuel temperature in the fuel tank, and a fuel for detecting volatility of the fuel in the fuel tank. Volatility detection means, abnormality diagnosis by the abnormality diagnosis means when a predetermined condition is satisfied based on the fuel temperature detected by the fuel temperature detection means and the volatility of the fuel detected by the fuel volatility detection means. And a diagnostic condition determining means that allows the start of the.

[0009]

In the self-diagnosis device for the first fuel processor, the pressure in the fuel tank is detected, and when the pressure is equal to or higher than the predetermined value, vapor is sufficiently generated and adsorbed by the adsorbent. Therefore, the start of abnormality diagnosis based on the temperature change of the adsorbent is allowed. As a result, it is possible to avoid a case where an abnormality is diagnosed when the temperature is not reduced by purging when vapor is not adsorbed on the adsorbent.

In the second self-diagnosis apparatus for the fuel processor, the adsorbent is detected when the fuel temperature in the fuel tank and the volatility of the fuel are detected and the vapor is sufficiently generated based on these. The start of abnormality diagnosis based on the temperature change of is allowed. That is, the higher the fuel temperature, the more easily vapor is generated, but the volatility varies depending on the type of fuel, and the higher the volatility at the same temperature, the more the vapor generation amount increases. Make a decision.

As with the first self-diagnosis device, this device can also avoid erroneous diagnosis when vapor is not adsorbed on the adsorbent.

[0012]

EXAMPLES Examples of the present invention will be described below. In FIG. 3 showing an embodiment, air is drawn into the engine 1 through a throttle chamber 2 and an intake manifold 3. The throttle chamber 2 is provided with a throttle valve 4 interlocking with an accelerator pedal (not shown) to control the intake air flow rate Q. The intake manifold 3 is provided with an electromagnetic fuel injection valve 5 for each cylinder,
Fuel, which is pressure-fed from a fuel pump (not shown) and is controlled to a predetermined pressure by a pressure regulator, is injected and supplied into the intake manifold 3. The control of the fuel injection amount by the fuel injection valve 5 is performed by the control unit 6 with a built-in microcomputer.

The engine 1 has a fuel tank 20.
The fuel vapor processing device 21 is provided. The fuel vapor processing apparatus 21 causes the adsorbent 23 such as activated carbon filled in the canister 22 to adsorb and collect the fuel vapor of the fuel generated in the fuel tank 20, and to collect the fuel adsorbed by the adsorbent 23. The air is supplied to the intake passage downstream of the throttle valve 4 via the purge passage 24.

The fuel vapor in the fuel tank 20 is introduced into the canister 22 through a fuel vapor passage 26 in which a check valve 25 that opens when the positive pressure in the fuel tank 20 exceeds a predetermined value. Further, the purge passage 24 is provided with a diaphragm valve 28 having a pressure chamber into which a throttle negative pressure is introduced via a negative pressure introduction passage 27.

The diaphragm valve 28 opens the purge passage 24 against the valve closing urging force of the spring 28a when the engine 1 rotates and a throttle negative pressure higher than a predetermined value is applied, and the throttle valve is opened when the engine 1 stops rotating. When the negative pressure becomes the atmospheric pressure, the valve is closed by the valve closing urging force of the spring 28a to close the purge passage 24, and the fuel is purged in an appropriate purge region.

On the upstream side of the diaphragm valve 28 in the negative pressure introducing passage 27, energization control (opening / closing control) is performed by the control unit 6, and the negative pressure introducing passage is opened when the valve is opened.
A solenoid valve 29 that opens 27 to guide the throttle negative pressure to the diaphragm valve 28, closes the negative pressure introduction path 27 when closing, and guides atmospheric pressure to the diaphragm valve 28 to close it.
Is installed.

Further, an adsorbent temperature sensor 30 is provided as an adsorbent temperature detecting means for detecting the temperature T _C of the adsorbent 23 in the canister 22. Meanwhile, the fuel tank 20
A pressure sensor 31 as a pressure detecting means for detecting the pressure inside the tank is provided on the upper wall of the tank. The control unit 6 controls the fuel injection amount of the fuel injection valve 5 based on the signals from the various sensors, and also performs the self-diagnosis control of the fuel vapor processing apparatus 21 including the opening / closing control of the solenoid valve 29. The self-diagnosis control will be described with reference to the flowchart of FIG.

In this embodiment, the functions as the diagnostic condition judging means and the abnormality diagnosing means are provided by software as shown in the flow chart of FIG. The program shown in the flowchart of FIG. 4 is executed when the ignition switch is turned on,
First, in step 1 (denoted as S1 in the figure; the same applies hereinafter), the solenoid valve 29 is opened to perform purging.

In step 2, the adsorbent temperature sensor 30
It is determined whether or not the temperature T _C of the adsorbent 23 detected by is decreased. If it is lowered, it is determined that the temperature has dropped due to the purging of the fuel adsorbed by the adsorbent 23, and it is determined in step 3 that the processing device 21 is normal. Although this diagnosis is different from the abnormality diagnosing means according to the present invention, it can be judged to be normal when there is a temperature drop, so the diagnosis is terminated without performing the abnormality diagnosis according to the present invention.

When the temperature T _C of the adsorbent 23 does not decrease, there are two possibilities that the purge pipe is broken due to breakage or the like to cause a purge leakage, or the vapor is not adsorbed on the adsorbent 23. Can be considered. Therefore, the process proceeds to step 4, where the solenoid valve 29 is closed and the purging is stopped. In step 5, it is judged whether or not the pressure in the tank detected by the pressure sensor 31 has reached a predetermined value or more.
However, immediately after purging is stopped, even if vapor is generated in the tank, the pressure does not rise yet. Therefore, the determination is made after waiting a predetermined time.

When the pressure in the tank has not reached the predetermined value, it is judged that vapor has not occurred and the diagnosis is stopped (step 6), but when it has reached the predetermined value, vapor occurs. If it is determined that the processing device 21 is abnormal, the process proceeds to step 7 and subsequent steps to diagnose whether the processing device 21 is abnormal. The function of this step 5 corresponds to the diagnostic condition determination means.

In step 7, it is judged whether or not the temperature T _C of the adsorbent 23 has risen. If the temperature T _C has not risen, the temperature does not rise even though the vapor has been adsorbed, so that the processing device 21 has failed. Judge (step 8). If the temperature T _C of the adsorbent 23 has risen, the routine proceeds to step 9, where the solenoid valve 29 is opened and purging is performed.

Then, in step 10, the temperature T _C of the adsorbent 23 is increased.
If it does not fall, it is judged to be normal (step 11), but if it does not fall, the temperature does not fall even though the adsorbed vapor has been purged. It is determined that 21 is defective (step 12). According to this diagnosis, since the presence or absence of abnormality is diagnosed after detecting the pressure in the fuel tank 20 and confirming that vapor has occurred, it is possible to avoid erroneous diagnosis in a state where vapor does not occur.

FIG. 5 shows an embodiment of a self-diagnosis device for a second fuel vapor processing apparatus according to the present invention. In this one,
Instead of the pressure sensor 31 provided in the fuel tank 20 in the above embodiment, a temperature sensor 32 as a fuel temperature detecting means for detecting the temperature of the fuel in the fuel tank 20, and a volatility of the fuel in the fuel tank 20 are also provided. A volatile sensor 33 is provided as a fuel volatility detecting means for detecting. As the volatility sensor 33, one that detects volatility by the difference in the refractive index of fuel is used.

In the self-diagnosis of this apparatus, instead of the determination based on the pressure in the fuel tank 20 in step 5 of FIG. 4, the vapor temperature in the fuel tank 20 is determined based on the detected fuel temperature and fuel volatility. When the occurrence status is grasped and it is judged that the vapor is occurring enough to make a diagnosis,
Proceed to step 7 to allow diagnosis. Also,
The diaphragm valve 28 and the canister 22 are separated from each other, and an electromagnetic flow control valve 40 that can variably control the opening degree and linearly control the purge flow rate is interposed between the purge passages 24 connecting the two. The flow control valve capable of the linear control is the first
Of course, it can be applied to the embodiment. The other points are the same as those of the first embodiment, and the same is true of the effect that erroneous diagnosis can be avoided in a state where no vapor is generated.

[0026]

As described above, according to the present invention, the pressure in the fuel tank is detected, or the fuel temperature and the volatility of the fuel are detected, and vapor is sufficiently generated based on these detected values. Since it is configured to diagnose whether or not there is an abnormality in the fuel vapor processing device, it is possible to make an error such as diagnosing that the fuel vapor processing device is abnormal even though the fuel vapor processing device is normal in the absence of vapor. Diagnosis can be avoided and diagnosis accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a first self-diagnosis apparatus for a fuel vapor processing apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of a self-diagnosis device for a second fuel vapor processing apparatus according to the present invention.

FIG. 3 is a diagram showing a configuration of an embodiment of a self-diagnosis device for the first fuel vapor processing apparatus.

FIG. 4 is a flowchart showing a self-diagnosis routine of the above embodiment.

FIG. 5 is a diagram showing a configuration of an embodiment of a self-diagnosis device for the second fuel vapor processing apparatus.

[Explanation of symbols]

1 engine 4 Throttle valve 6 control unit 20 Fuel tank 21 Fuel vapor treatment equipment 22 canister 23 Adsorbent 29 Solenoid valve 30 Adsorbent temperature sensor 31 Pressure sensor 32 Temperature sensor 33 Volatile sensor

Claims (2)

[Claims] 1. A structure in which fuel vapor evaporated in a fuel tank is adsorbed and collected by an adsorbent, and the fuel adsorbed by the adsorbent is supplied to an engine through the purge passage under predetermined engine operating conditions. In the self-diagnosis device of the fuel vapor processing apparatus, the self-diagnosis apparatus includes an abnormality diagnosing unit for diagnosing the presence or absence of abnormality in the fuel vapor processing apparatus based on the temperature of the adsorbent detected by the adsorbent temperature detecting unit An internal tank pressure detecting means for detecting the internal pressure; and a diagnostic condition determining means for permitting the abnormality diagnosing means to start abnormality diagnosis when the pressure detected by the tank internal pressure detecting means is a predetermined value or more. A self-diagnosis device for a fuel vapor processing device, characterized in that 2. A structure in which fuel vapor evaporated in a fuel tank is adsorbed and collected by an adsorbent, and the fuel adsorbed by the adsorbent is supplied to an engine through the purge passage under predetermined engine operating conditions. In the self-diagnosis apparatus of the fuel vapor processing apparatus, the self-diagnosis apparatus of the fuel vapor processing apparatus includes abnormality diagnosis means for diagnosing the presence or absence of abnormality in the fuel vapor processing apparatus based on the temperature of the adsorbent detected by the adsorbent temperature detection means. Temperature detecting means for detecting the fuel temperature in the fuel tank, fuel volatility detecting means for detecting the volatility of the fuel in the fuel tank, fuel temperature detected by the fuel temperature detecting means and the fuel volatility detecting means And a diagnostic condition determining means for permitting the abnormality diagnosis means to start the abnormality diagnosis when a predetermined condition is satisfied based on the volatility of the fuel detected by Self-diagnosis apparatus for a fuel vapor processing apparatus characterized by a.