JPH0842413A - Evaporated fuel treating equipment - Google Patents

Abstract

PURPOSE:To promote the miniaturization of evaporated fuel treating equipment in heightening the adsorptive function of evaporated fuel in time of fueling and the desorption function in time of engine driving respectively, by heating a canister at a time when a fuel residual quantity in a fuel tank is still abundant but when it is little, suspending the heating the other way. CONSTITUTION:A float 12 moves up and down according to the height of a level of fuel in a fuel tank 1, therefore when a fuel quantity is much, it goes up, and a movable contact 13c comes into contact with two fixed contacts 13a and 13b, whereby a switch 13 is turned on. Likewise, the float 12 goes down if the quantity in the tank 1 becomes lessened attendingly, and when the movable contact 13c separates from these fixed contacts 13a and 13b, the switch 13 is turned off. The fuel quantity in the case of the switch 13 turned off is a time it has come to that requires an oil charge. On end of an electric heater 11 stored in a adsorbent 8 of a canister 6 is connected to the contact 13a of the switch 13, and the other end is connected to a contact 15a of a key switch 15, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporative fuel which adsorbs evaporated fuel generated in a fuel tank during parking or refueling, desorbs it during engine operation, burns it, and prevents it from being released into the atmosphere. Regarding a processing device.

[0002]

2. Description of the Related Art In a fuel system of a vehicle engine, a fuel component (hydrocarbon HC) (hereinafter referred to as "evaporated fuel") of fuel (gasoline vapor) evaporated in a fuel tank is released into the atmosphere during parking. Alternatively, an evaporated fuel processing device is provided to prevent the fuel tank from being discharged into the atmosphere from the fueling port of the filler neck of the fuel tank during fueling. As shown in FIG. 1, this evaporative fuel processing device is provided with an upper part in a fuel tank 1, a fuel cut valve 3 for controlling a liquid level to prevent an excessive amount of fuel, and a fuel leaking from the fuel tank 1 when the vehicle falls. A rollover valve 4 for preventing the above-mentioned operation and a canister 6 for adsorbing the evaporated fuel are connected via a vent hose 5. Canister 6
Is filled with an adsorbent (activated carbon) 8 in a canister container 7 so as to adsorb evaporated fuel. The canister container 7 is provided with a tank port 7a connected to the fuel tank 1, a purge port 7b connected to the intake passage of the engine, and an atmosphere port 7c opening to the atmosphere.

If the internal pressure of the fuel tank 1 rises above the fuel tank 1 due to the evaporated fuel when the fuel cut valve 3 is closed, the valve is opened to allow the evaporated fuel to escape to the canister 6 for lowering the tank internal pressure. A 2-way valve 9 is provided. The 2-way valve 9 is connected in parallel to the fuel cut valve 3. The evaporated fuel generated in the fuel tank 1 during parking flows into the canister 6 from the tank port 7a through the vent hose 5, the fuel component is adsorbed by the adsorbent 8 and then released into the atmosphere from the atmospheric port 7a. Also, when refueling,
Evaporated fuel generated in the fuel tank 1 in a short time when fuel is supplied to the fuel tank 1 from the filler opening of the filler neck 2 flows into the canister 6 through the vent hose 5 and is adsorbed by the adsorbent 8. This prevents evaporative fuel from being released into the atmosphere from the filler port of the filler neck 2 during refueling.

The evaporated fuel adsorbed in the canister 6 is desorbed (purged) from the adsorbent 8 by the atmosphere introduced from the atmospheric port 7c due to the negative pressure in the intake passage during engine operation, and the purge port is introduced together with the introduced atmosphere. It is supplied to the intake passage of the engine from 7b and burned. As a result, the adsorbent 8 of the canister 6 recovers its adsorbing ability and prepares for adsorbing the evaporated fuel at the next parking or refueling.

[0005]

By the way, the adsorption / desorption capacity of the adsorbent (activated carbon) 8 greatly depends on the temperature,
Moreover, the adsorption capacity decreases as the temperature rises as shown by the curve I in FIG. 2, while the desorption capacity decreases as the temperature decreases as shown by the curve II in the opposite relationship. Furthermore, if the adsorbent 8 adsorbs gasoline vapor in a short time during refueling, heat of adsorption is generated, and the adsorbing capacity is significantly reduced accordingly.

Further, it has been remarkably restricted that the evaporated fuel is released into the atmosphere at the time of refueling (on-board restriction), and in order to cope with this, the canister changes from an engine room with a high temperature to a fuel tank with a low temperature. Are being placed in the vicinity of. As a result, canister 6
There is a problem that the temperature of the (adsorbent 8) decreases and it becomes difficult for the evaporated fuel adsorbed by the adsorbent 8 to be desorbed during engine operation. When it becomes difficult for the canister 6 to desorb the evaporated fuel from the adsorbent 8, the recovery of the adsorbing capacity of the adsorbent 8 becomes poor, and the evaporated fuel generated in the fuel tank 1 is adsorbed during the next parking or refueling. It is not preferable because the ability is reduced.

The present invention has been made in view of the above-mentioned points, and the evaporated fuel processing apparatus is designed to improve the adsorbing capacity of the evaporated fuel during refueling and to increase the desorbing capacity during operation of the engine for downsizing. The purpose is to provide.

[0008]

In order to achieve the above object, according to the present invention, a canister which is connected to an upper portion of a fuel tank and adsorbs evaporated fuel, and a fuel for detecting the amount of fuel in the fuel tank. A configuration is provided that includes an amount detection unit, a heating unit that heats the canister, and a control unit that stops heating when the fuel amount detection unit detects that the fuel amount is less than or equal to a predetermined amount.

In the apparatus of claim 2, the heating means is composed of an electric heater. In the device of claim 3, the first
It has a passage and a second passage passing near or inside the canister, and the exhaust gas passing through the second passage is a heating means. The device according to claim 4 has a first passage and a second passage that passes near or inside the canister,
The return fuel returning from the engine to the fuel tank through the second passage is constituted by the heating means.

According to a fifth aspect of the present invention, there is provided a first passage and a second passage passing near or inside the canister, and the cooling water for the engine passing through the second passage is a heating means. is there. According to the sixth aspect of the present invention, the predetermined amount is the amount of fuel at which the fuel warning light indicating that the fuel in the fuel tank is low is turned on.

According to the seventh aspect of the present invention, the fuel warning lamp is turned on based on the detection result of the fuel amount detecting means.

[0012]

The evaporated fuel generated in the fuel tank during parking or refueling flows into the canister, and the fuel component is adsorbed and removed by the adsorbent. When the amount of fuel in the fuel tank is large, the canister is heated by the heating means when the engine is operating, and the desorption capacity is increased. As a result, the desorption of the adsorbed vaporized fuel becomes favorable, and the recovery becomes faster. When the amount of fuel in the fuel tank becomes small and the remaining amount of fuel is reached, heating of the canister by the heating means is stopped. This results in a lower canister temperature and a higher adsorption capacity.

According to the second aspect of the invention, the heating means is an electric heater, and it is possible to efficiently perform heating at a low temperature or immediately after starting the engine. According to the third aspect of the invention, the device has a first passage and a second passage that passes near or inside the canister, and the heating means is exhaust gas that passes through this second passage, so that the structure is simple. According to the fourth aspect of the present invention, the canister is heated by the return fuel that has the first passage and the second passage near or inside the canister and returns from the engine to the fuel tank through the second passage. In this case,
The temperature of the return fuel can be lowered, and the generation of evaporated fuel in the fuel system can be suppressed.

According to a fifth aspect of the present invention, there is provided a first passage and a second passage passing near or inside the canister. When the canister is heated by the cooling water for the engine passing through the second passage, the engine cooling water is used. Is cooled and the cooling efficiency of the engine is increased. In the device of the sixth aspect, the remaining amount of fuel in the fuel tank at which the heating of the canister is stopped is set as the amount of fuel at which the fuel warning light indicating that the fuel in the fuel tank is low is turned on.

In the device of the seventh aspect, the fuel warning lamp is turned on based on the detection result of the fuel amount detecting means, and the existing system can be used.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The same members as those in FIG. 1 are designated by the same reference numerals. In FIG. 3, a filler neck 2 for refueling the fuel tank 1 has a lower portion 2a which is liquid-tightly penetrated and fixed to a lower portion of a side wall of the fuel tank 1 and slightly protrudes substantially horizontally into the fuel tank 1. The upper end 2b is opened obliquely upward from the fuel tank 1, and the opening end (fuel filler port) 2 is opened.
A cap (not shown) is liquid-tightly and detachably attached to c.

In the canister 6, partition walls 7d and 7e are provided on both sides in the canister container 7 to define chambers 7f and 7g, and an adsorbent (activated carbon) 8 is provided between these partition walls 7f and 7e. It is filled. The chamber 7f has a tank port 7a connected to the rollover valve 4 via a vent hose 5 and a communication port connected to an intake passage of the engine (both not shown) via a purge port 7b.
The chamber 7g is open to the atmosphere via the atmosphere port 7c. The partition walls 7d and 7e are made of, for example, punching metal having many small holes. Then, a heating means such as an electric heater 11 is provided in the adsorbent 8.
Is stored.

On the other hand, in the fuel tank 1, the float 12
And a switch 13 which is opened and closed by the float 12. The switch 13 is fixed to the upper surface 1a in the fuel tank 1, and has two fixed settings 13a and 1
3b and a movable contact 13c are provided. Moving contact 1
3c is arranged below the fixed settings 13a and 13b, the upper end of the rod 14 is fixed to the movable contact 13c, and the float 12 is fixed to the lower end of the rod 14.

The float 12 moves up and down according to the height of the liquid surface of the fuel in the fuel tank 1, and rises when the amount of fuel is large. The movable contact 13c abuts the fixed contacts 13a and 13b, and the switch 13 Turns on. Also, float 1
When the amount of fuel in the fuel tank 1 becomes small, 2 moves down, and when the movable contact 13c is separated from the fixed contacts 13a and 13b, the switch 13 is turned off. The amount of fuel for which the switch 13 is turned off is when the amount of fuel that requires refueling, for example, is 20% or less of the nominal capacity.

One end of the electric heater 11 housed in the adsorbent 8 of the canister 6 is connected to the contact 1 of the switch 13.
3a and the other end is the contact 15 of the key switch 15.
connected to a. The contact 13 of the switch 13
b is grounded, and the contact 15b of the key switch 15 is connected to the power supply + V. The key switch 15 is turned on when the engine is operating.

The operation will be described below. Evaporative fuel (gasoline vapor) generated in the fuel tank 1 during parking etc.
Through the vent hose 5 to the chamber 7 of the canister 6.
f, and diffuses into the adsorbent 8 through a large number of small holes of the partition wall 7d. The diffused fuel vapor is adsorbed and removed by the adsorbent 8. The vapor from which the fuel component has been removed flows into the chamber 7g through a large number of small holes in the partition wall 7e and is discharged into the atmosphere from the atmosphere port 7c. At the time of parking, the temperature of the fuel tank 1 is low and the temperature of the canister 6 is low, and the adsorption capacity of the adsorbent 8 is high (curve I in FIG. 2). Therefore, the canister 6 can favorably adsorb the evaporated fuel generated in the fuel tank 1.

When the amount of fuel in the fuel tank 1 is large and the liquid level is high, the float 12 is rising and the movable contact 13
The switch 13 is turned on by the contact of c with the fixed contacts 13a and 13b. In this state, the key switch 15
When the engine is operated by operating the
When a and 15b are connected, they are switched on. As a result, the electric heater 11 is connected to the power source + V to generate heat and heat the adsorbent 8. When the adsorbent 8 is heated and its temperature rises, its desorption capacity increases (curve II in FIG. 2) and desorbs the adsorbed fuel component. As a result, the recovery of the adsorbent 8 becomes faster. The separated fuel component is burned by the engine.

When the amount of fuel in the fuel tank 1 is reduced and the remaining amount for refueling, for example, 20% or less of the above-mentioned nominal capacity, the switch 13 is turned off and the key switch 1
That is, 5 is turned on, that is, even when the engine is in operation, the electric power to the electric heater 11 is stopped and the heating of the adsorbent 8 is stopped. Along with this, the temperature of the adsorbent 8 decreases. When the temperature becomes low, the canister 6 has a high adsorption capacity, and adsorbs the evaporated fuel generated in the fuel tank 1 favorably. As a result, the canister 6 has a high capability of adsorbing the evaporated fuel during refueling. That is, when the amount of fuel in the fuel tank 1 is large, the temperature of the adsorbent 8 of the canister 6 is increased to increase the desorption capacity, and when the fuel is supplied with a small amount of fuel, the temperature of the adsorbent 8 is decreased to increase the adsorption capacity. To do.

FIG. 4 shows a second embodiment of the present invention. Instead of the electric heater 11, the pipe 16 is housed in the adsorbent 8 of the canister 6 in a meandering manner, and one end 16a of the passage 17 for the engine cooling water is provided. A switching valve connected in the middle, for example, is connected to the port 18c of the three-way switching solenoid valve 18, and the other end 16b is connected to the engine cooling water passage 17 on the upstream side of the solenoid valve 18. That is, the pipe 16 is connected to the engine cooling water passage 17 via the three-way switching electromagnetic valve 18. By making the pipe 16 meander inside the adsorbent 8, the contact area with the adsorbent 8 increases, and the heat exchange efficiency increases. The solenoid of the three-way switching solenoid valve 18 has one end connected to the fixed contact 13a of the switch 13 and the other end connected to the fixed contact 15a of the key switch 15. When the three-way switching solenoid valve 18 is energized, the ports 18b and 18c communicate with each other, the port 18a is closed, and when deenergized, the port 18c is closed and the ports 18a and 18b communicate with each other. It

When the amount of fuel in the fuel tank 1 is large, the switch 13 is on and the three-way switching solenoid valve 18
Are energized when the engine is running and are connected to ports 18c and 18
b and the port 18a is closed. As a result, high temperature engine cooling water flows into the pipe 16 to heat the adsorbent 8 of the canister 6. This allows the canister 6
The desorption ability of is increased.

When the amount of fuel in the fuel tank 1 reaches such a level that fuel can be supplied and the switch 13 is turned off, the three-way switching solenoid valve 18 is deenergized, the port 18c is closed, and the ports 18a and 18b are opened. Communicated. As a result, the flow of engine cooling water to the pipe 16 is stopped, and the temperature of the canister 6 drops. This increases the adsorption capacity of the canister 6.

It should be noted that, in FIG. 4, it is possible to replace the engine cooling water as the heating means and to flow the surplus fuel that is recirculated from the engine to the fuel tank 1 when the engine is operating, that is, the return fuel. The return fuel is heated when flowing near the cylinder of the engine and is heated to a high temperature (60 to 70 °).
C), and the canister 6 can be heated sufficiently.

Alternatively, in FIG. 4, the exhaust gas of the engine may be passed as the heating means instead of the engine cooling water or the return fuel. In this case, the exhaust gas is very hot, and therefore a portion of the exhaust gas flowing through the pipe 16 is sufficient to heat the canister 6. Further, in the above-mentioned embodiment, the fuel amount to be supplied as the fuel amount in the fuel tank 1 in which the switch 13 is operated, for example, the case where the fuel amount is reduced to 20% or less of the nominal capacity is described, but the present invention is not limited to this. , Fuel tank 1
It may be the fuel amount when the fuel warning light that informs the driver that the fuel amount in the inside has decreased. Further, the fuel warning light may be turned on depending on the detection result of the fuel amount by the float 12 and the switch 13.

[0029]

As described above, according to the present invention, the evaporated fuel can be efficiently desorbed from the canister by heating the canister when the remaining fuel amount is large according to the fuel amount in the fuel tank. By stopping heating when the remaining fuel amount is small, the evaporated fuel can be adsorbed efficiently during refueling, and as a result, the capacity of the canister can be reduced.

According to the second aspect of the present invention, the heating of the canister can be efficiently performed as needed, for example, at a low temperature or immediately after starting. According to the third aspect of the present invention, the heating of the canister can be easily performed, the structure is simple, and the number of newly added portions is small. Claim 4
According to the invention, the temperature of the return fuel can be lowered by heating the canister with the return fuel, and accordingly, the generation of the evaporated fuel in the fuel system can be reduced.

According to the fifth aspect of the present invention, the temperature of the engine cooling water can be lowered by heating the canister with the engine cooling water, and the cooling effect of the engine can be enhanced. According to the sixth aspect of the present invention, the heating is stopped when the amount of fuel that is frequently refueled becomes high, so that the evaporated fuel can be more effectively adsorbed.

According to the invention of claim 7, it can be added to the existing fuel warning display system and is easy to implement.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a conventional evaporated fuel processing device.

FIG. 2 is a graph showing a temperature characteristic of an adsorbent used in an evaporated fuel processing device.

FIG. 3 is a cross-sectional view of essential parts showing a first embodiment of the evaporated fuel processing apparatus according to the present invention.

FIG. 4 is a cross-sectional view of essential parts showing a second embodiment of the evaporated fuel processing apparatus according to the present invention.

[Explanation of symbols]

 1 Fuel Tank 2 Filler Neck 3 Fuel Cut Valve 4 Rollover Valve 5 Vent Hose 6 Canister 7 Canister Container 7a, 7b, 7c Port 7d, 7e Partition 7f, 7g Chamber 8 Adsorbent 9 2-way Valve 11 Electric Heater 12 Float 13 Switch 15 Key switch 16, 17 Pipe 18 3 way switching solenoid valve

Continued Front Page (72) Inventor Yoichiro Ando 5-3-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation

Claims (7)

[Claims] 1. A canister which is connected to an upper portion of a fuel tank and adsorbs evaporated fuel, a fuel amount detecting means for detecting a fuel amount in the fuel tank, a heating means for heating the canister, and the fuel amount. And a control means for stopping heating when the detection means detects that the amount is equal to or less than a predetermined amount. 2. The evaporated fuel processing apparatus according to claim 1, wherein the heating means is an electric heater. 3. The evaporated fuel according to claim 1, further comprising a first passage and a second passage passing near or inside the canister, and the exhaust gas passing through the second passage is the heating means. Processing equipment. 4. The heating means includes return fuel having a first passage and a second passage near or inside the canister, the return fuel returning from the engine to the fuel tank through the second passage. The evaporated fuel processing device according to claim 1. 5. A first passage and a second passage passing near or inside the canister, and the cooling water of the engine passing through the second passage is the heating means. The evaporated fuel processing device described. 6. The evaporated fuel processing apparatus according to claim 1, wherein the predetermined amount is a fuel amount at which a fuel warning lamp indicating that the fuel in the fuel tank is low is turned on. 7. The evaporated fuel processing apparatus according to claim 6, wherein the fuel warning light is turned on based on a detection result of the fuel amount detection means.