JP2532346Y2 - Fuel vapor emission suppression device for internal combustion engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor emission control device for an internal combustion engine which prevents fuel vapor generated in a fuel supply system of the internal combustion engine from being released into the atmosphere.

[0002]

2. Description of the Related Art Conventional fuel vapor emission suppression devices include:
As shown in FIG. 3, a fuel tank 51 and a canister 52 that adsorbs and stores fuel vapor are provided, and a two-way valve 54 is interposed in a communication pipe 53 that communicates the fuel tank 51 and the canister 52. Have been.

In the above fuel vapor emission suppressing device, when the fuel vapor generated in the fuel tank 51 reaches a predetermined set pressure, the fuel vapor pushes the positive pressure valve of the two-way valve 54 to open and flows into the canister 52. Then, it is adsorbed by the adsorbent 55 in the canister 52 and is temporarily stored in the canister 52. When the engine rotates, the canister 52
The fuel vapor stored in the engine is sucked together with the outside air sucked from an outside air inlet 56 provided in the canister 52 by a negative pressure of an intake pipe (not shown), and is sent from a purge pipe 57 through an intake pipe to a cylinder of the engine. Sent to

When the fuel tank 51 is cooled by the influence of the outside air and the negative pressure in the fuel tank 51 increases, the negative pressure valve of the two-way valve 54 is opened, and the fuel vapor stored in the canister 52 is opened. Is returned to the fuel tank 51. In this way, the two-way valve 5 is controlled so that the inside of the fuel tank 51 has a constant pressure.
4 to prevent the fuel vapor generated in the fuel tank 51 from being released to the atmosphere.

[0005]

However, in the above-mentioned conventional fuel vapor emission suppression device, for example, when the fuel temperature rises while the vehicle is running, the tank internal pressure rises and the two-way valve 54
Is applied to the fuel tank 51 as the tank internal pressure, so that when fuel is supplied by opening the filler cap 58, the fuel vapor in the fuel tank 51 is released into the atmosphere, causing air pollution. There are drawbacks.

As means for solving this drawback, a bypass pipe is provided for bypassing the two-way valve 54 via an electromagnetic valve, and the electromagnetic valve is opened when the engine is running to open the fuel tank 5.
There is a conceivable measure for reducing the internal pressure of the fuel tank 51 by connecting the canister 1 to the canister 52.

However, in the above-described fuel vapor emission suppression device, when dust or the like adheres to the outside air intake 56 of the canister 52 due to aging or the like, the ventilation resistance of the outside air intake 56 increases, and furthermore, the outside air intake increases. The entrance 56 may be closed.

When such a situation occurs, in the above-described method in which the solenoid valve is provided in the bypass pipe so that the fuel tank 51 and the canister 52 are always in communication with each other when the engine is operating, the adsorbent in the canister 52 The fuel vapor adsorbed and stored in 55 increases, and finally the adsorption by the adsorbent 55 becomes supersaturated. Therefore, the deterioration of the adsorbent 55 may be promoted, or the communication pipe 53 and the purge pipe 57 may be short-circuited. That is, when the adsorption of the adsorbent 55 in the canister 52 becomes supersaturated, the fuel vapor from the fuel tank 51 flows out to the purge pipe 57 without being adsorbed by the adsorbent 55 of the canister 52, and
As a result, the fuel vapor directly flows into the cylinder of the engine, and the fuel vapor leaks from each seal portion.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and prevents the fuel vapor in the fuel tank from being released into the atmosphere even when fuel is supplied by simple improvement and devising. It is an object of the present invention to provide a fuel vapor emission suppression device for an internal combustion engine that can ensure the amount of purge of a canister while ensuring the amount of canister purge.

[0010]

According to the present invention, there is provided a fuel tank, a canister for adsorbing and storing fuel vapor, and a communication for communicating the fuel tank with the canister via a two-way valve. In a fuel vapor emission suppression device for an internal combustion engine provided with a pipe, a bypass pipe bypassing the two-way valve, a control valve interposed in the bypass pipe, and operating state detecting means for detecting an operating state of the internal combustion engine And a tank internal pressure detecting means for detecting an internal pressure of the fuel tank, and when the operation of the engine is detected by the operating state detecting means, the control valve is opened while the tank internal pressure detecting means detects the operation. A control valve opening / closing means for closing the control valve when the tank internal pressure is equal to or lower than a predetermined value.

A bypass pipe for bypassing the two-way valve; a control valve interposed in the bypass pipe; operating state detecting means for detecting an operating state of the internal combustion engine; and a fuel temperature detecting means for detecting a fuel temperature Means for opening the control valve when the operation of the engine is detected by the operating state detecting means, while opening the control valve when the fuel temperature detected by the fuel temperature detecting means is equal to or lower than a predetermined value. The control valve opening / closing means for closing the valve may be provided.

[0012]

According to the above construction, the control valve is opened when the operation of the engine is detected by the operation state detecting means. Therefore, when the engine is operating, the internal pressure of the fuel tank is reduced and the fuel vapor from the fuel tank is discharged. It flows into the canister through the bypass pipe and is adsorbed and stored.

When the tank internal pressure detected by the tank internal pressure detecting means is equal to or lower than a predetermined value, the control valve is closed, so that the fuel vapor is controlled by the two-way valve, and the canister purge amount can be secured. .

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of a fuel vapor emission suppression device for an internal combustion engine according to the present invention.

In FIG. 1, reference numeral 1 denotes an internal combustion engine having, for example, four cylinders (hereinafter simply referred to as "engine"). A throttle body 3 is provided in the middle of an intake pipe 2 of the engine 1, and a throttle body 3 is provided therein. A throttle valve 3 'is provided. The throttle valve 3 'has a throttle valve opening (θ
A TH) sensor 4 is connected, and outputs an electric signal corresponding to the opening of the throttle valve 3 ′ and supplies it to an electronic control unit (hereinafter referred to as “ECU”) 5.

The fuel injection valve 6 is provided for each cylinder between the engine 1 and the throttle valve 3 'and slightly upstream of an intake valve (not shown) of the intake pipe 2. Each fuel injection valve 6 is connected to the fuel pump 7 via a fuel supply pipe 25 and is also electrically connected to the ECU 5. The valve opening time of the fuel injection is controlled by a signal from the ECU 5.

A purge pipe 8 is provided on the downstream side of the throttle valve 3 ′ of the intake pipe 2, and the purge pipe 8 is connected to a fuel vapor discharge suppression system 9 described later.

Further, a branch pipe 10 is provided downstream of the purge pipe 8, and an absolute pressure (P
BA) Sensor 11 is provided. The PBA sensor 11 is electrically connected to the ECU 5, and the absolute pressure PBA in the intake pipe 2 detected by the PBA sensor 11 is converted into an electric signal and supplied to the ECU 5.

An engine speed (NE) sensor 12 is provided around a camshaft or a crankshaft (not shown) of the engine 1.
Is attached.

The NE sensor 12 outputs a signal pulse (hereinafter, referred to as a “TDC signal pulse”) at a predetermined crank angle position every time the crankshaft of the engine 1 rotates 180 degrees, and the TDC signal pulse is supplied to the ECU 5. .

An ignition switch (IGSW) sensor 13 is an IG indicating that the engine 1 is operating.
The ON state of the SW is detected and the electric signal is supplied to the ECU 5.

The fuel vapor emission suppression system 9 is provided with a fuel tank 15 having a filler cap 14 which is opened when fuel is supplied, an adsorbent (activated carbon) 16 and an outside air intake 17. A canister 18, a communication pipe 19 that communicates the canister 18 with the fuel tank 15, and a two-way valve 20 having a positive pressure valve 20 a and a negative pressure valve 20 b interposed in the communication pipe 19. ,
A bypass pipe 21 for bypassing the two-way valve 20, and a solenoid valve (control valve) 22 interposed in the middle of the bypass pipe 21.
It is composed of A tank internal pressure (PT) sensor 23 is provided above the fuel tank 15. Then, the PT sensor 23 detects the pressure in the fuel tank 15 and supplies an electric signal to the ECU 5.

Further, the canister 18 is connected to the intake pipe 2 via a purge control valve 24 and a purge pipe 8, and the fuel tank 15 is connected to the fuel injection valve 6 via a fuel pump 7 and a fuel supply pipe 25. I have.

The solenoid valve 22 and the purge control valve 24
Is electrically connected to the ECU 5, and the open / close state of the electronic valve 22 and the purge control valve 24 is controlled by a signal from the ECU 5.

The ECU 5 has an input circuit having the functions of shaping the input signal waveforms from the various sensors described above, correcting the voltage level to a predetermined level, converting an analog signal value to a digital signal value, and the like, and a central processing circuit. (Hereinafter referred to as “CPU”), storage means for storing an operation program executed by the CPU, operation results, and the like;
2 and an output circuit for supplying a drive signal to the purge control valve 24.

The CPU opens the solenoid valve 22 when the operation of the engine is detected by the IGSW sensor 13. On the other hand, when the internal pressure of the tank detected by the PT sensor 23 is lower than a predetermined value (for example, 10 mmHg), the CPU opens the solenoid valve. An electromagnetic valve opening / closing means for closing the valve 22 is provided.

In the fuel vapor emission suppressing device configured as described above, when the IGSW is turned on, the operation of the engine 1 is detected by the IGSW sensor 13, and the output signal is supplied to the ECU 5. Next, the solenoid valve 22
The valve is opened in response to a signal from 5. This allows the fuel tank 1
The fuel vapor in the fuel tank 15 flows into the canister 18, the internal pressure of the fuel tank 15 decreases, and the fuel vapor is adsorbed by the adsorbent 16 of the canister 18. Is stored.

On the other hand, when the tank internal pressure detected by the PT sensor 23 falls below a predetermined value (for example, 10 mmHg), the solenoid valve 22 is closed, and the outflow of fuel vapor from the fuel tank 15 is controlled by the two-way valve 20. You.

That is, when the tank internal pressure is lower than the predetermined value, the line of the bypass pipe 21 is shut off and the fuel tank 1
Since the outflow of the fuel vapor from the fuel tank 5 is controlled by the two-way valve 20, the purge amount of the canister 18 can be secured.

When the solenoid valve 22 is closed, the tank internal pressure is low, and the two-way valve 20 controls the fuel tank 15.
Since the outflow of the fuel vapor from the fuel is controlled, the fuel vapor does not scatter to the atmosphere even when the filler cap 14 is opened to supply the fuel, and the supercharging can be prevented.

FIG. 2 is a block diagram of a main part of a fuel vapor emission suppressing device according to a second embodiment of the present invention. In the embodiment, a fuel temperature (TF) comprising a thermistor or the like is used in place of the PT sensor 23 in the first embodiment. ) A sensor 26 is inserted in a proper position in the fuel tank 15.

Since the fuel temperature TF increases as the tank internal pressure increases, and decreases as the tank internal pressure decreases, the TF sensor 26 may be used instead of the PT sensor 23 as in the first embodiment. Similar functions and effects can be obtained.

That is, when the engine is operating, the solenoid valve 22
To open the fuel vapor in the fuel tank 15 to the canister 1.
8, the fuel vapor is adsorbed and stored in the adsorbent 16 of the canister 18, and when the fuel temperature TF detected by the TF sensor 26 falls below a predetermined value, the electromagnetic valve 22 is closed, and the fuel By controlling the outflow of the fuel vapor by the two-way valve 20, the purge amount of the canister 18 can be secured.

[0035]

As described in detail above, the present invention provides an internal combustion engine having a fuel tank, a canister for adsorbing and storing fuel vapor, and a communication pipe for communicating the fuel tank with the canister via a two-way valve. In the fuel vapor emission suppression device for an engine, a bypass pipe bypassing the two-way valve, a control valve interposed in the bypass pipe, operating state detecting means for detecting an operating state of the internal combustion engine, Tank internal pressure detecting means for detecting an internal pressure, wherein the control valve is opened when the operation of the engine is detected by the operating state detecting means, while the tank internal pressure detected by the tank internal pressure detecting means is a predetermined value. Since the control valve opening / closing means for closing the control valve when the value is equal to or less than the value is provided, when the engine is operated in which the fuel temperature increases and the generation of fuel vapor increases, It communicates the fuel tank with the canister through the bypass tube, with the internal pressure of the fuel tank is reduced, the fuel vapor is adsorbed and stored in the canister. When the tank internal pressure is equal to or lower than the predetermined value, the control valve is closed, so that the internal pressure of the fuel tank is controlled by the two-way valve.

That is, when the control valve is closed as described above, since the tank internal pressure is low, even when the fuel supply port is opened, the release of fuel vapor to the atmosphere is suppressed and the fuel vapor canister is opened. Is controlled by a two-way valve, and the purge amount of the canister is secured.

Since the increase / decrease of the internal pressure of the fuel tank and the increase / decrease of the fuel temperature are in a proportional relationship, a fuel temperature detecting means for detecting the fuel temperature is provided in place of the tank internal pressure detecting means. Control valve opening / closing means for opening the control valve when the operation is detected, and closing the control valve when the fuel temperature detected by the fuel temperature detection means is equal to or lower than a predetermined value. The same effect as described above can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing one embodiment (first embodiment) of a fuel vapor emission suppression device for an internal combustion engine according to the present invention.

FIG. 2 is a main part configuration diagram of a second embodiment.

FIG. 3 is a main part configuration diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 internal combustion engine 5 ECU (control valve opening / closing means) 13 IGSW sensor (operating state detecting means) 15 fuel tank 18 canister 19 communication pipe 20 two-way valve 22 solenoid valve (control valve) 23 PT sensor (tank pressure detecting means) 26 TF Sensor (fuel temperature detecting means)

Claims (2)

(57) [Scope of request for utility model registration] 1. A fuel vapor emission suppression device for an internal combustion engine, comprising: a fuel tank, a canister that adsorbs and stores fuel vapor, and a communication pipe that communicates the fuel tank with the canister via a two-way valve. A bypass pipe for bypassing the two-way valve, a control valve interposed in the bypass pipe, operating state detecting means for detecting an operating state of the internal combustion engine, and tank internal pressure detecting means for detecting an internal pressure of the fuel tank; And the control valve is opened when the operation of the engine is detected by the operating state detecting means, while the control valve is opened when the tank internal pressure detected by the tank internal pressure detecting means is equal to or less than a predetermined value. A fuel vapor emission suppression device for an internal combustion engine, comprising a control valve opening / closing means for closing a valve. 2. A fuel vapor emission suppression device for an internal combustion engine, comprising: a fuel tank, a canister for adsorbing and storing fuel vapor, and a communication pipe communicating the fuel tank and the canister via a two-way valve. A bypass pipe for bypassing the two-way valve, a control valve interposed in the bypass pipe, an operating state detecting means for detecting an operating state of the internal combustion engine, and a fuel temperature detecting means for detecting a fuel temperature; A control valve that opens the control valve when the operation of the engine is detected by the operating state detection means, and closes the control valve when the fuel temperature detected by the fuel temperature detection means is equal to or lower than a predetermined value. A fuel vapor emission suppression device for an internal combustion engine, comprising an opening / closing means.