JPH05180092A - Vaporized fuel control device - Google Patents

Abstract

PURPOSE:To prevent a bad influence to an internal combustion engine without accumulating a large amount of liquefied fuel to stay in the bottom part of a canister by controlling a pump for the liquefied fuel actuated for a fixed time at the time of starting and stopping the internal combustion engine, in a control means. CONSTITUTION:A liquefied fuel recirculating passage 24 is provided to connect its one end side to the bottom part of a canister 12 and also the other end side of this liquefied fuel recirculating passage 24 into a fuel tank 8. A liquefied fuel pump 26 for supplying liquefied fuel in the canister 12 to a side of the fuel tank 8 is provided on the halfway of the liquefied fuel recirculating passage 24. Further, a control means 28, which controls the liquefied fuel pump 26 actuated for a fixed time at the time of starting and stopping an internal combustion engine 2, is provided. Thus by forcing the liquefied fuel in the canister 12 recirculated in the fuel tank, a large amount of the liquefied fuel is prevented from staying in the canister 12, to prevent a bad influence to the internal combustion engine 2, and also performance of the canister 12 can be well maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporated fuel control device, and more particularly to an evaporated fuel control device capable of forcibly recirculating liquefied fuel generated in a canister to a fuel tank to prevent adverse effects on an internal combustion engine. ..

[0002]

2. Description of the Related Art Evaporative fuel that leaks into the atmosphere from a fuel tank, a float chamber of a vaporizer, etc., contains a large amount of hydrocarbons (HC) and is one of the causes of air pollution. Therefore, various techniques for preventing this are known. As a typical example,
2. Description of the Related Art There is an evaporative fuel control device that causes a canister containing an adsorbent such as activated carbon to separate (purge) the evaporative fuel from a fuel tank during operation of the internal combustion engine and supply the evaporated fuel to the internal combustion engine.

In this fuel vapor control system, as shown in FIG. 2, a fuel tank 102 and an intake system of an internal combustion engine 104 communicate with an intake passage 108 downstream of the throttle valve 106 by an air passage 110. In addition, the vaporized fuel generated in the fuel tank 102 is adsorbed and held by the adsorbent containing the fuel while the internal combustion engine 104 is stopped, and the vaporized fuel is adsorbed and held by the introduction of fresh air from the atmosphere introduction port 112 while the internal combustion engine 104 is operating. Intake passage 1 by removing fuel (purging)
A canister 112 for supplying the gas to the fuel cell 08 is provided, and a purge valve 114 is provided in the intake passage 110 between the canister 112 and the intake passage 108. Further, in this evaporated fuel control device, the evaporated fuel in the canister 112 is supplied to the intake passage 108 by the negative pressure that is the intake pipe pressure.

In the canister 112, fresh air is introduced from the atmosphere introducing port 112 communicating with the upper portion, and evaporated fuel flows from the purge communicating passage 116 on the bottom 112d side of the canister 112 to the intake passage 108 side.

Such an evaporated fuel control device is disclosed, for example, in Japanese Patent Application Laid-Open No. 60-147561. The publication described in this publication discloses an evaporated fuel passage, one end of which opens into an intake passage of an internal combustion engine, a pump and a check valve provided in this evaporated fuel passage, and a control circuit for driving the pump for a certain period of time after the engine is stopped. Is installed to forcibly perform scavenging in the intake passage for a certain time automatically after the internal combustion engine is stopped.
It is to improve the restartability even in a vehicle in which the engine room has a particularly high temperature such as an FF vehicle.

[0006]

By the way, in the conventional evaporated fuel control device, the evaporated fuel in the canister is only purged by the intake pipe pressure (negative pressure), so there is no problem at high temperature, When the temperature becomes low, the evaporated fuel in the canister liquefies, and the liquefied fuel stays at the bottom of the canister where the purge communication passage exists.This causes the liquefied fuel to adversely affect the internal combustion engine and the performance of the canister. There was an inconvenience that it decreased.

[0007]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention is arranged in the middle of a ventilation passage communicating between the inside of a fuel tank and the intake passage of the intake system of the internal combustion engine while the internal combustion engine is stopped. In an evaporative fuel control device provided with a canister that adsorbs and holds evaporative fuel generated in the fuel tank and releases the evaporative fuel that is adsorbed and held by introduction of fresh air during operation of the internal combustion engine and supplies it to the intake passage, The one end side of the liquefied fuel recirculation passage is connected to the bottom of the canister, and the other end side of the liquefied fuel recirculation passage is provided in communication with the inside of the fuel tank, and the liquefied fuel in the canister is provided in the middle of the liquefied fuel recirculation passage. A pump for supplying liquefied fuel to the fuel tank side and controlling the operation of the liquefied fuel pump for a certain period of time when the internal combustion engine is started and stopped. The is characterized in that provided.

[0008]

According to the structure of the present invention, the control means controls the operation of the liquefied fuel pump for a certain period of time when the internal combustion engine is started and stopped. As a result, the liquefied fuel generated in the canister is forcibly recirculated into the fuel tank, so that the liquefied fuel does not stay in the bottom of the canister in a large amount and the adverse effect on the internal combustion engine is prevented and Good performance can be maintained.

[0009]

Embodiments of the present invention will now be described in detail and specifically with reference to the drawings. FIG. 1 shows an embodiment of the present invention. Reference numeral 2 is an internal combustion engine, 4 is an intake passage, 6 is a throttle valve, and 8 is a fuel tank. Inside the fuel tank 8 and throttle valve 6
The air intake passage 4 communicates with the intake passage 4 on the downstream side. A canister 12 that accommodates an adsorbent such as activated carbon that adsorbs evaporated fuel is provided in the air passage 10. As a result, the air passage 10 is divided into the first air passage 10-1 between the fuel tank 8 and the canister 12 and the second air passage 10-2 between the canister 12 and the intake passage 4.

The first ventilation passage 10-1 has one end 10-
1a is opened in the upper portion of the fuel tank 8, and the other end 10-1b is opened by extending substantially vertically from the upper portion of the canister 12 to the vicinity of the bottom portion 12d.

The second ventilation passage 10-2 has one end 10-
2a is opened from the bottom portion 12d of the canister 12 to the side portion of the canister 12 through a stepped portion 14 that slightly rises, and the other end portion 10-2b, which is a purge port, is provided in the intake passage downstream of the throttle valve 6. 4 is opened.

An atmosphere introducing port 16 for introducing fresh air is provided in communication with the upper portion of the canister 12.

Further, in the middle of the second ventilation passage 10-2,
A purge valve 18 is provided. The purge valve 18 is operated by, for example, a control unit 28 described later, and controls the purge amount (desorption amount) of the evaporated fuel from the canister 12 to the intake passage 4.

One end side of the liquefied fuel communication passage 20 is communicated with the bottom portion 12d of the canister 12, and the liquefied fuel passage 2
A liquefied fuel chamber 22 is provided on the other end side of 0. The liquefied fuel chamber 22 is provided below the bottom portion 12d of the canister 12 and stores the liquefied evaporated fuel in the canister 12.

At the lower portion of the liquefied fuel chamber 22,
One end portion 24-a of the liquefied fuel recirculation passage 24 is provided so as to communicate with each other. The other end portion 24 of the liquefied fuel recirculation passage 24-
b is opened at an upper portion in the fuel tank 8.

A liquefied fuel pump 26 is interposed in the liquefied fuel recirculation passage 24.

The liquefied fuel pump 26 has a control means 2
When the internal combustion engine 2 is started and stopped, the operation of the liquefied fuel chamber 22 is controlled for a certain period of time (for example, the time until the liquefied fuel in the liquefied fuel chamber 22 is almost exhausted).
The liquefied fuel (1) is forcibly recirculated into the fuel tank 8.

The control means 28 has a starter signal generator 30 for generating signals when the internal combustion engine 2 is started and stopped.
And the rotation angle sensor 32 are in communication with each other.

Next, the operation of this embodiment will be described.

When the internal combustion engine 2 is stopped, the evaporated fuel generated in the fuel tank 8 is guided to the canister 12 via the first ventilation passage 10-1 and is adsorbed and held by the adsorbent in the canister 12.

When the internal combustion engine 2 is operated, the intake pipe pressure (negative pressure) causes the vaporized fuel adsorbed and held by the introduction of fresh air from the atmosphere introduction port 16 to be released (purged).
Then, the throttle valve 6 is supplied to the intake passage 4 on the downstream side. At this time, the amount of vaporized fuel supplied to the intake passage 4 is controlled by the purge valve 18.

By the way, when the evaporated fuel is adsorbed by the adsorbent in the canister 12, when the temperature becomes low, the evaporated fuel is liquefied and becomes liquid. This liquefied fuel is
It flows into the liquefied fuel chamber 22 from the liquefied fuel communication passage 20 communicating with the bottom portion 12d and is stored in the liquefied fuel chamber 22.

When the internal combustion engine 2 is started or stopped, the control means 28 operates the liquefied fuel pump 26 for a certain period of time, whereby the liquefied fuel in the liquefied fuel chamber 22 is forcibly recirculated into the fuel tank 8. It

As a result, the bottom portion 12d in the canister 12 is
Since a large amount of liquefied fuel does not stay in the internal combustion engine 2, the internal combustion engine 2 is prevented from being adversely affected, and the evaporated fuel in the canister 12 can be effectively treated. Even if the canister has a small capacity, the function of the canister is reduced. Can be sufficiently exerted, and the evaporated fuel can be prevented from leaking from the fuel supply system to the atmosphere.

[0025]

As is apparent from the above detailed description, according to the present invention, one end of the liquefied fuel recirculation passage is communicated with the bottom of the canister and the other end of the liquefied fuel recirculation passage is communicated with the inside of the fuel tank. A liquefied fuel pump for supplying the liquefied fuel in the canister to the fuel tank is provided in the middle of the liquefied fuel recirculation passage, and a control means for controlling the operation of the liquefied fuel pump for a certain time at the time of starting and stopping the internal combustion engine is provided. Since the liquefied fuel in the canister is forcibly recirculated into the fuel tank by the provision, the liquid fuel does not stay in the canister in a large amount, preventing the internal combustion engine from being adversely affected and improving the performance of the canister. It can be maintained well.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an evaporated fuel control device.

FIG. 2 is a system configuration diagram of a conventional evaporated fuel control device.

[Explanation of symbols]

 2 Internal combustion engine 4 Intake passage 8 Fuel tank 10 Vent passage 22 Liquefied fuel chamber 24 Liquefied fuel recirculation passage 26 Liquefied fuel pump 28 Control means

Claims (1)

[Claims] 1. An evaporated fuel generated in the fuel tank is adsorbed and held while the internal combustion engine is stopped, while adsorbing and holding evaporated fuel generated in the fuel tank while the internal combustion engine is stopped, in the middle of a ventilation passage that connects the inside of the fuel tank and the intake passage of the intake system of the internal combustion engine. In a vaporized fuel control device provided with a canister for separating the vaporized fuel adsorbed and held by the introduction of fresh air and supplying it to the intake passage, one end side of the liquefied fuel recirculation passage is connected to the bottom of the canister and The other end of the recirculation passage is provided so as to communicate with the inside of the fuel tank, and a liquefied fuel pump for supplying the liquefied fuel in the canister to the fuel tank is provided in the middle of the liquefied fuel recirculation passage. An evaporated fuel control device comprising a control means for controlling the operation of the liquefied fuel pump for a certain period of time at the time of starting and stopping.