JPH06193518A - Failure diagnostic device for evaporation fuel supplying device - Google Patents

Abstract

PURPOSE:To suppress flow-in of liquid fuel so as to reduce deterioration of a canister by suppressing fuel to flow into the canister when intake negative pressure acts at the time of failure detection between a fuel tank and the canister. CONSTITUTION:In an evaporation fuel supplying device P1, evaporation fuel of a fuel tank P2 is adsorbed to a canister P3, and this evaporation fuel is led into the intake system P6 of an engine P5 through a purge valve P4. An opening/closing valve P9 provided on the atmospheric port of the canister P3 is closed by a failure detecting means P7 when failure of a purge system passage P8 is detected, and intake negative pressure is forced to act on the purge system passage P8 through the purge valve P4. Then, pressure change of this purge system passage P8 is detected by a pressure sensor P10, and failure of the purge system passage P8 is detected by this pressure change. Fuel flow into the canister P3 is suppressed by a suppressing means P11 provided between the fuel tank P2 and the canister P3 when intake negative pressure acts at the time of failure detection. It is thus possible to reduce deterioration of the canister P3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure diagnosing device for an evaporated fuel supply system which adsorbs evaporated fuel in a fuel tank to a canister and introduces the evaporated fuel into an intake system of an engine through a purge valve.

[0002]

2. Description of the Related Art Conventionally, as a failure diagnosing apparatus for an evaporated fuel supply apparatus of the above-mentioned example, there is an apparatus described in Japanese Utility Model Laid-Open No. 3-17169. That is, while the evaporated fuel in the fuel tank is adsorbed by the canister, and the evaporated fuel adsorbed and collected by the canister is introduced into the intake passage downstream of the throttle valve through the purge line, the above-mentioned purge fuel is provided. A pressure sensor such as a pressure gauge for detecting the pressure of the purge line is provided in the line, and when the failure diagnosis condition outside the purge region is satisfied, for example, when the engine is idle, negative intake pressure (boost negative pressure) is applied to the purge line to output the pressure sensor. This is a device configured to perform a failure diagnosis of leakage, clogging, etc. of the purge system path based on (pressure of the purge line).

In this conventional device, when negative suction pressure is applied between the fuel tank and the canister at the time of failure diagnosis,
Liquid fuel adhering to the purge line between the two is sucked into the canister due to the intake negative pressure, and the activated carbon surface in the canister is covered with the liquid fuel, so the canister deteriorates and the evaporated fuel adsorption capacity of the canister. However, there was a problem in that

[0004]

The invention according to claim 1 (the first invention) of the present invention suppresses the inflow of fuel into the canister during the action of the intake negative pressure when a failure is detected between the fuel tank and the canister. An object of the present invention is to provide a failure diagnosis device for an evaporated fuel supply device, which can suppress the deterioration of the canister by suppressing the liquid fuel from flowing into the canister due to the intake negative pressure action when the failure is detected. And

According to a second aspect of the present invention (the second invention), a fuel reservoir provided between the fuel tank and the canister and fuel in the fuel reservoir before failure detection are supplied to the intake system. By configuring the above-mentioned suppressing means with the supply means, the liquid fuel stored in the fuel reservoir before the failure detection is supplied to the intake system via the supply means, so that the intake negative pressure action occurs when the failure is detected. An object of the present invention is to provide a failure diagnosis device for an evaporated fuel supply device that can reliably prevent liquid fuel from flowing into a canister and prevent deterioration of the canister.

[0006]

According to a first aspect of the present invention, the evaporated fuel in the fuel tank is adsorbed to the canister, and the evaporated fuel is introduced into the intake system of the engine through the purge valve. Evaporative fuel supply device, an on-off valve that opens and closes the atmosphere port of the canister, a pressure sensor provided between the fuel tank and the canister, and the on-off valve is closed, and the purge valve is used. An evaporative fuel supply apparatus comprising: an intake load acting on a purge system passage; a pressure change in the purge system passage is detected by the pressure sensor; and failure detection means for detecting a failure in the purge system passage based on the pressure change. A failure diagnosis device, wherein evaporated fuel supply is provided between the fuel tank and the canister, and a suppression means is provided for suppressing fuel inflow into the canister when an intake negative pressure acts at the time of failure detection. Characterized in that it is a trouble diagnosis device for the location.

According to a second aspect of the present invention (the second invention), an evaporated fuel supply device for adsorbing evaporated fuel in a fuel tank to a canister and introducing the evaporated fuel into an intake system of an engine through a purge valve is provided. An on-off valve that opens and closes the atmosphere port of the canister, a pressure sensor that is provided between the fuel tank and the canister, and the on-off valve is closed, and an intake load is applied to the purge system passage through the purge valve. And a failure detecting means for detecting a pressure change in the purge system passage by the pressure sensor and detecting a failure in the purge system passage by the pressure change. A suppressing means is provided between the fuel tank and the canister for suppressing fuel inflow into the canister when an intake negative pressure is applied when a failure is detected, and the suppressing means is a fuel tank. A failure diagnosis device for an evaporated fuel supply device, comprising: a fuel reservoir provided between the canister and a supply means for supplying the fuel in the fuel reservoir to the intake system before a failure is detected. .

[0008]

According to the invention (first invention) described in claim 1 of the present invention, as shown in the claim correspondence diagram of FIG. 6, the evaporated fuel supply device P1 transfers the evaporated fuel in the fuel tank P2 to the canister P3. Adsorbed on the purge valve P
4 is introduced into the intake system P6 of the engine P5, and the failure detection means P7 closes the opening / closing valve P9 provided at the atmospheric port of the canister P3 when the failure of the purge system passage P8 is detected, and the purge valve P4. An intake negative pressure is applied to the purge system passage P8, and the pressure change in the purge system passage P8 is detected by the pressure sensor P10.
And the failure of the purge system path P8 is detected by this pressure change. Moreover, the suppressing means P11 provided between the fuel tank P2 and the canister P3 described above suppresses the fuel inflow to the canister P3 when the intake negative pressure acts at the time of failure detection.

As described above, since the above-mentioned suppressing means suppresses the inflow of the liquid fuel into the canister during the action of the intake negative pressure at the time of failure detection, there is an effect that the deterioration of the canister can be reduced. .

According to the second aspect of the present invention (the second aspect of the invention), the liquid fuel stored in the fuel storage portion before the failure detection is supplied to the intake system of the engine through the supply means. Therefore, when a failure is detected, it is possible to reliably prevent the liquid fuel from flowing into the canister due to the intake negative pressure action, prevent the canister from deteriorating, and maintain the evaporated fuel adsorbing capability of the canister. There is an effect.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a system diagram of a reciprocating engine equipped with a failure diagnosis device for an evaporated fuel supply device. In FIG. 1, an air flow sensor 3 is connected to a rear side of an element 2 of an air cleaner 1 for purifying intake air. 3 is configured to detect the intake air amount Q.

A throttle body 4 is connected to the rear of the air flow sensor 3 described above, and a throttle chamber 5 in the throttle body 4 is provided with a throttle valve 6 for controlling the amount of intake air. And this throttle valve 6
A surge tank 7 as an expansion chamber having a predetermined capacity is connected to the downstream intake passage, an intake manifold 9 communicating with the intake port 8 is connected downstream of the surge tank 7, and an injector 10 is connected to the intake manifold 9. Are installed.

On the other hand, the intake port 8 and the exhaust port 13 which are in proper communication with the combustion chamber 12 of the engine 11 are
Intake valve 14 which is opened and closed by a valve mechanism (not shown)
The exhaust valve 15 and the exhaust valve 15 are attached to the cylinder head, and an ignition plug (not shown) having a spark gap facing the combustion chamber 12 is attached to the cylinder head.

An O 2 sensor 17 as an air-fuel ratio sensor is arranged in an exhaust passage 16 communicating with the above-mentioned exhaust port 13, and a catalytic converter 18 so-called catalyst for detoxifying harmful gas is provided behind the exhaust passage 16. And an O ₂ sensor 20 as an air-fuel ratio sensor is attached to the exhaust passage 19 downstream of the catalytic converter 18.

Further, a bypass passage 21 for bypassing the above-mentioned throttle valve 6 is provided, and an ISC valve 22 as an ISC (idle speed control) mechanism is provided in the bypass passage 21, while the air cleaner 1 is provided with a downstream side of the element 2. The intake air temperature sensor 23, the throttle body 4 is provided with a throttle sensor 24, and the water jacket is provided with a water temperature sensor 25.

On the other hand, the evaporated fuel supply device 26 is shown in FIGS.
It is configured as shown in. That is, the evaporated fuel supply device 26 includes a canister 27 and a purge valve 28 including a duty solenoid valve, and the fuel tank 2
9 and the inlet side 27in of the canister 27 are connected by a first purge line 32 having a line upstream portion 30 and a line downstream portion 31, and an outlet side 27 of the canister 27 is connected.
The above-described purge valve 28 is provided in the second purge line 33 provided at out, and the second purge line 33 downstream of the purge valve 28 is connected to the surge tank 7 as an intake system, so that the fuel vapor evaporated in the fuel tank 29 is transferred to the canister. Adsorbed on the activated carbon layer 34 in 27, the evaporated fuel is purged by the purge valve 2
It is configured to be introduced into the intake system (specifically, the surge tank 7) of the engine 11 via 8.

Further, between the fuel tank 29 and the canister 27 described above, there is provided a suppressing means 35 for suppressing the inflow of liquid fuel into the canister 27 at the time of the action of the intake negative pressure when the failure is detected.

In this embodiment, the above-mentioned suppressing means 35 is constructed as follows. That is, as shown in FIG. 2, the fuel reservoir 36 is provided between the fuel tank 29 and the canister 27.
Is provided, and the lower portion of the fuel reservoir 36 and the second purge line 33 downstream of the purge valve 28 are connected to the supply line 37.
A solenoid valve SOLA is provided in the supply line 37, and the fuel in the fuel reservoir 36 is supplied to the intake system via the supply line 37 by utilizing the intake negative pressure before the failure is detected. The supply means is constituted, and both the supply means (solenoid valve SOLA and supply line 37) and the above-mentioned fuel reservoir 36 constitute the suppression means 35. In addition, it is desirable that the above-mentioned fuel reservoir 36 is arranged at a position close to the canister 27.

A solenoid valve SOLB as an opening / closing valve and a filter 3 are provided at the atmosphere port 38 of the canister 27 described above.
9. The atmospheric pressure introducing port 41 is connected via the check valve 40 to prevent water or the like from entering the inside of the canister 27 by the above-mentioned check valve 40, while dust enters the inside of the canister 27 by the above-mentioned filter 39. It is configured to prevent this.

Further, a pressure sensor 42 for detecting a pressure change in the purge system passage is provided at the line downstream portion 31 of the first page line 32, while the line upstream portion 30 of the first purge line 32 is provided at the line upstream portion 30. A solenoid valve SOLC, which is opened only when the engine is operating, is provided.

Fuel is supplied to the injector 10 from a fuel pump provided in a fuel tank 29 through a fuel filter and a fuel inlet pipe, and a pressure regulating valve is provided in a fuel return line of the injector 10. ing.

FIG. 3 shows a control circuit of a failure diagnosing device for the evaporated fuel supply device. The CPU 50 is integrally formed with the intake air amount Q from the air flow sensor 3, the engine speed Ne from the distributor 43, and the throttle sensor 24. The purge valve 28 and the solenoid valves SOLA, S are operated in accordance with a program stored in the ROM 45 based on various necessary signal inputs such as the ON / OFF signals from the idle switch 44 and the measured pressure P from the pressure sensor 42.
OLB, SOLC, delay timer 46, failure diagnosis unit 4
7, and the RAM 48 stores necessary data and maps.

Here, the above-mentioned purge valve 28 is duty-controlled during the normal operation by the purge valve drive time (map value of the purge map stored in the RAM 48) determined by both the load CE and the engine speed Ne. It is a solenoid valve.

The above-mentioned delay timer 46 is a timer for setting the delay time T in the time chart shown in FIG.
The timer 46 may be configured by a timer with a built-in CPU instead of the above configuration.

Further, the above-mentioned failure diagnosis section 47 closes the above-mentioned solenoid valve SOLB at the time of failure diagnosis of the purge system passage 49 (see FIG. 2), and applies the intake negative pressure to the purge system passage 49 via the purge valve 28. It is a failure detection means that is operated to detect a pressure change in the purge system path 49 by the pressure sensor 42 and detects a failure in the purge system path 49 based on the pressure change.

The operation of the failure diagnosing device for the evaporated fuel supply system thus constructed will be described in detail below with reference to the flow chart shown in FIG. 4 and the time chart shown in FIG.
In the first step S1, the CPU 50 causes the idle switch 4
Various necessary signals such as ON and OFF signals from 4 are read, and in the next second step S2, the CPU 50 determines whether or not the failure diagnosis condition is satisfied. In this embodiment, failure diagnosis is performed when the intake negative pressure is relatively high during idling, so it is determined whether or not the idle switch 44 is ON, and during idling (time t in the time chart of FIG. 5).
1), the process proceeds to the next third step S3.

In this third step S3, the CPU 50 closes the purge valve 28, and in the next fourth step S4, C
PU50 opens the solenoid valve SOLA. Thus, the purge valve 28 is closed and the solenoid valve SOLA is closed.
Is controlled to be open, the liquid fuel adhering to the inner wall surface of the conduit of the purge system passage 49 is temporarily accumulated in the fuel reservoir 36 by the intake negative pressure, and then the intake air of the engine is supplied via the supply line 37. As it is supplied to the system, the canister 27
Liquid fuel can be prevented from flowing into the activated carbon layer 34 inside.

Next, in a fifth step S5, the CPU 50 determines whether or not the delay time T by the delay timer 46 has elapsed, in other words, whether or not the delay time T from the time point t1 to the time point t2 of the tasm chart shown in FIG. 5 is reached, Only when the delay time T has elapsed, the process proceeds to the next sixth step S6.

In the above-mentioned sixth step S6, the CPU 50 closes the solenoid valves SOLA and SOLB, and in the next seventh step S7, the CPU 50 opens the purge valve 28 to apply the intake negative pressure to the purge system passage 49. Let Then the eighth
In step S8, the pressure change of the purge system passage 49 is measured by the pressure sensor 42, and in the next ninth step S9, the CPU
Numeral 50 executes a failure diagnosis by the above-mentioned failure diagnosis section 47 based on the pressure P signal from the pressure sensor 42.

As described above, the liquid fuel stored in the fuel storage portion 36 before the failure detection including the steps S6 to S9 is supplied to the intake system of the engine through the supply line 37 by the intake negative pressure. Therefore, there is an effect that it is possible to reliably prevent the liquid fuel from flowing into the canister 27 due to the action of the intake negative pressure at the time of detecting a failure, to prevent the deterioration of the canister 27, and to improve the evaporated fuel adsorption capacity of the canister 27. There is an effect that can be maintained.

In the correspondence between the configuration of the present invention and the above-described embodiment, the intake system of the engine of the present invention corresponds to the surge tank 7 of the embodiment, and hereinafter, similarly, the opening / closing valve for opening / closing the atmospheric opening of the canister. Corresponds to the solenoid valve SOLB, the failure detection means corresponds to the failure diagnosis negative section 7, and the control means corresponds to the fuel reservoir section 36, the solenoid valve SOLA, and the supply line 37. The present invention is not limited to the structure of the embodiment, and for example, the above-mentioned structure is V
Needless to say, the invention may be applied to a failure diagnosis device in an evaporated fuel supply device for a diesel engine.

[Brief description of drawings]

FIG. 1 is a system diagram of an engine equipped with a failure diagnosis device for an evaporated fuel supply device according to the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a block diagram of a control circuit.

FIG. 4 is a flowchart showing a failure diagnosis process of the evaporated fuel supply device.

FIG. 5 is a time chart.

FIG. 6 is a diagram for responding to a complaint.

[Explanation of symbols]

 7 ... Surge tank (intake system) 26 ... Evaporative fuel supply device 27 ... Canister 28 ... Purge valve 29 ... Fuel tank 35 ... Suppression means 36 ... Fuel reservoir 37 ... Supply line 38 ... Atmosphere port 42 ... Pressure sensor 47 ... Failure diagnosis unit 49 ... Purge system path SOLA ... Solenoid valve SOLB ... Solenoid valve (open / close valve)

Claims (2)

[Claims] 1. An evaporated fuel supply device for adsorbing evaporated fuel in a fuel tank to a canister and introducing the evaporated fuel into an intake system of an engine through a purge valve; an on-off valve for opening and closing an atmospheric opening of the canister; The pressure sensor provided between the fuel tank and the canister and the on-off valve are closed, and an intake load is applied to the purge system passage through the purge valve, and a pressure change in the purge system passage is controlled by the pressure change. A failure diagnosis device for an evaporated fuel supply device, comprising a failure detection means for detecting a failure of the purge system passage by a pressure change detected by a sensor, and detecting a failure between the fuel tank and the canister. A failure diagnosis device for an evaporated fuel supply device, which is provided with a suppressing means for suppressing the inflow of fuel into the canister when the intake negative pressure is applied. 2. An evaporated fuel supply device for adsorbing evaporated fuel in a fuel tank to a canister and introducing the evaporated fuel into an intake system of an engine through a purge valve; an on-off valve for opening and closing an atmospheric opening of the canister; The pressure sensor provided between the fuel tank and the canister and the on-off valve are closed, and an intake load is applied to the purge system passage through the purge valve, and a pressure change in the purge system passage is controlled by the pressure change. A failure diagnosis device for an evaporated fuel supply device, comprising a failure detection means for detecting a failure of the purge system passage by a pressure change detected by a sensor, and detecting a failure between the fuel tank and the canister. Is provided with a suppressing means for suppressing fuel inflow into the canister when the intake negative pressure acts, and the suppressing means includes a fuel storage portion provided between the fuel tank and the canister, Before detecting the failure diagnosis apparatus for evaporative fuel supply apparatus constructed in accordance with a supply means for supplying fuel of the fuel reservoir into the intake system.