JPH07237460A - Fuel processing device for internal combustion engine - Google Patents

Abstract

PURPOSE:To completely impede flowing out into the outside air of vaporized fuel generated in a fuel tank. CONSTITUTION:Upper part space of a fuel tank 8 is connected to a charcoal canister 9 through a ventilation control valve 16. The ventilation control valve 16 has an opening/closing valve 17, opened when supplied fuel oil, and a check valve 18. When the opening/closing valve 17 is opened at supply time of fuel oil, vaporized fuel in the fuel tank 8 is adsorbed to an activated carbon layer 10 in the charcoal canister 9. When a negative pressure is generated in the fuel tank 8, the check valve 18 is opened, to generate the atmospheric pressure in the fuel tank 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel processor for an internal combustion engine.

[0002]

2. Description of the Related Art A pressurized air passage is branched from an engine intake passage downstream of a supercharger, the pressurized air passage is connected to a fuel tank, and an atmosphere opening hole is formed in the pressurized air passage to form a supercharger. The pressurized air discharged from the machine was introduced into the pressurized air passage and the fuel tank, and a part of the pressurized air was discharged from the atmosphere opening hole so that the pressure in the fuel tank was maintained at a positive pressure. Internal combustion engines are known (Japanese Patent Laid-Open No. 54-151727).
(See the official gazette). In this internal combustion engine, the pressurized air continues to flow out from the atmosphere opening hole while the engine is operating, so that it is possible to prevent dust in the outside air from entering the fuel tank.

[0003]

However, in this internal combustion engine, since the inside of the fuel tank communicates with the outside air through the atmosphere opening hole, the evaporated fuel in the fuel tank flows out through the atmosphere opening hole to the outside. Thus, there is a problem of causing air pollution.

[0004]

In order to solve the above problems, according to the present invention, a fuel processing apparatus is provided in which fuel vapor in a fuel tank is prevented from flowing out of the fuel tank except when fuel is refueled. The upper space in the tank is connected to the charcoal canister via a ventilation control valve that opens when fuel is refueled and when the pressure in the fuel tank becomes negative.

Further, according to the present invention, in order to solve the above problems, fuel is supplied from the fuel tank to the fuel injection valve without providing a fuel return passage for returning excess fuel from the fuel injection valve into the fuel tank. Only the fuel supply passage for supply is provided. Further, according to the present invention, in order to solve the above-mentioned problems, the fuel tank is composed of a plurality of fuel tanks which are communicated with each other, and a fuel refueling oil supply pipe is provided in the fuel tank whose installation position is the lowest among these fuel tanks. Connected.

[0006]

In the first aspect of the invention, the vaporized fuel in the fuel tank does not flow out of the fuel tank except when the fuel is refueled, and the ventilation control valve opens when the fuel is refueled. It flows out from and is adsorbed in the charcoal canister. When the pressure in the fuel tank becomes negative, the evaporated fuel desorbed from the charcoal canister is fed into the fuel tank.

In the second aspect of the invention, the fuel that has once flowed from the fuel tank to the fuel injection valve via the fuel supply passage does not return to the fuel tank again. In the third invention, the fuel is supplied to the fuel tank having the lowest installation position.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, 1 is an engine body, 2 is a piston, 3 is an intake valve, 4 is an exhaust valve, 5 is an intake passage, 6 is a throttle valve, 7 is a fuel injection valve, 8 is a fuel tank, 9 indicates charcoal canisters, respectively. The charcoal canister 9 has an activated carbon layer 10 therein, and the activated carbon layer 10
Atmosphere chamber 11 and evaporative fuel chamber 12 open to the atmosphere on both sides of
And are provided. The evaporative fuel chamber 12 is connected to the intake passage 5 downstream of the throttle valve 6 via the purge conduit 13 and the purge control valve 14 on the one hand, and to the upper space of the fuel tank 8 via the conduit 15 and the ventilation control valve 16 on the other hand. It is connected.

The ventilation control valve 16 is an on-off valve 1 arranged in parallel.
7 and a check valve 18. The check valve 18 is a check valve that can flow only from the evaporated fuel chamber 12 of the charcoal canister 9 into the fuel tank 8. A fuel supply pump 19 is arranged at the bottom of the fuel tank 8, and a discharge port of the fuel supply pump 19 is provided with a reservoir 22 via a relief valve 20 and a fuel supply conduit 21 arranged in the fuel tank 8.
Connected to. The reservoir 22 is connected to the fuel injection valve 7 of each cylinder via a corresponding conduit 23.

A fuel cap 25 is removably attached to the tip of the fuel supply pipe 24 of the fuel tank 8, and a fuel supply nozzle guide 26 is formed in the fuel supply pipe 24. Further, in the fuel supply pipe 24, a vaporized fuel outflow prevention valve 28 is rotatable about a pivot 27 and normally closes the lower end opening of the fuel supply nozzle guide 26 by a spring force of a spring (not shown) as shown in FIG. Are placed. The tip of the oil supply pipe 24 projects into a recess 30 formed on the vehicle body 29, and an opening / closing lid 31 capable of closing the recess 30 is attached to the vehicle body 29 so as to be rotatable around a pivot 32. . Further, a detection switch 33 that engages with the opening / closing lid 31 and detects that the opening / closing lid 31 is opened is attached to the vehicle body 29.

The electronic control unit 40 comprises a digital computer, and a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, a CPU (Microprocessor) 44, an input port 45 which are mutually connected by a bidirectional bus 41. And an output port 46. A water temperature sensor 34 that generates an output voltage proportional to the engine cooling water temperature is attached to the engine body 1, and the output voltage of the water temperature sensor 34 is input to an input port 45 via an AD converter 47. Further, the input port 45 has an ON signal of the detection switch 33 and the ignition switch 3
The ON signal of No. 5 is input. On the other hand, the output port 46 is connected to the purge control valve 14, the opening / closing valve 17 and the fuel supply pump 19 via the corresponding drive circuits 48, respectively.

Next, the operation of the fuel processor shown in FIG. 1 will be described with reference to the time interruption routine shown in FIG. In the embodiment shown in FIG. 1, electric power is supplied to the electronic control unit 40 even if the ignition switch 35 is turned off. Referring to FIG. 2, first, at step 50, it is judged if the ignition switch 35 is on. Ignition switch 3
When 5 is on, the routine proceeds to step 51, where the fuel supply pump 19 is driven. When the fuel supply pump 19 is driven, the fuel discharged from the fuel supply pump 19 is sent into the reservoir 22 via the relief valve 20 and the fuel supply conduit 21. The relief valve 20 opens when the fuel pressure becomes equal to or higher than the set pressure, and the surplus fuel is discharged into the fuel tank 8 again. Therefore, the fuel pressure in the reservoir 22 is maintained at the predetermined set pressure.

As shown in FIG. 1, in this embodiment, a fuel return conduit for returning excess fuel from the fuel injection valve 7 or the reservoir 22 to the fuel tank 8 is not provided. The fuel supplied to the reservoir 22, especially the fuel supplied to the fuel injection valve 7, is heated by the heat generated by the engine, so that the temperature of these fuels becomes high. In this case, if this high-temperature fuel is returned to the fuel tank 8 via the fuel return conduit, the fuel temperature in the fuel tank 8 rises, and a large amount of fuel evaporates from the fuel in the fuel tank 8. Become. However, in the embodiment shown in FIG. 1, the fuel return conduit is not provided, and therefore, the high temperature fuel is not returned to the fuel tank 8, so that the amount of the evaporated fuel generated in the fuel tank 8 is reduced. It will be possible.

Returning to FIG. 2 again, when the fuel supply pump 19 is driven at step 51, the routine proceeds to step 52, where it is judged if the conditions for purging the evaporated fuel into the intake passage 5 are satisfied. For example, when it is determined that the engine cooling water temperature is equal to or higher than a predetermined set temperature and the engine warm-up is completed, it is considered that the conditions for purging are satisfied. When the purge condition is not satisfied, the routine proceeds to step 53, where the purge control valve 14 is opened. On the other hand, when the purge condition is satisfied, the routine proceeds to step 54, where the purge control valve 14 is opened, so that the vaporized fuel adsorbed in the activated carbon layer 10 of the charcoal canister 9 at this time is activated carbon layer 10. And is purged into the intake passage 5 through the purge conduit 13.

On the other hand, when it is judged at step 50 that the ignition switch 35 is off, the routine proceeds to step 55, where the purge control valve 14 is closed.
Next, at step 56, the fuel supply pump 19 is stopped. Next, at step 57, the detection switch 3
It is determined whether or not 3 is on. Detection switch 33
Is not on, that is, as shown in FIG.
When 1 is closed, the routine proceeds to step 58, where the on-off valve 17 is closed.

When the fuel cap 25 is attached to the fuel supply pipe 24 of the fuel tank 8, the inlet opening of the fuel supply pipe 24 is completely closed by the fuel cap 25. On the other hand, as described above, the open / close valve 17 is closed when the open / close lid 31 is closed. Further, the check valve 18 is closed when the pressure in the fuel tank 8 is higher than the atmospheric pressure.
Therefore, as shown in FIG. 1, the opening / closing lid 31 is closed,
Moreover, when the pressure in the fuel tank 8 is higher than the atmospheric pressure, the fuel tank 8 is in a sealed state in which it is completely shielded from the outside air. This is the same when the ignition switch 35 is turned on and the fuel supply pump 19 is operated. Therefore, at this time, the evaporated fuel in the fuel tank 8 is not released to the outside air at all.

On the other hand, when the pressure in the fuel tank 8 becomes lower than atmospheric pressure, that is, when the pressure in the fuel tank 8 becomes negative, the check valve 18 opens, so that the pressure in the fuel tank 8 becomes almost atmospheric pressure. Therefore, the fuel tank 8 is prevented from being deformed. By providing such a check valve 18, the pressure in the fuel tank 8 is always higher than the atmospheric pressure. When the check valve 18 opens, the evaporated fuel desorbed from the activated carbon layer 10 of the charcoal canister 9 is fed into the fuel tank 8 via the conduit 16 and the check valve 18. Therefore, even at this time, the evaporated fuel in the fuel tank 8 does not flow into the outside air at all.

On the other hand, when the opening / closing lid 31 is opened for refueling, the detection switch 33 is turned on. Therefore, at this time, the routine proceeds from step 57 to step 59 in FIG.
Is opened. When the open / close valve 17 is opened, the evaporated fuel in the fuel tank 8 is removed from the open / close valve 17 and the conduit 15.
It is sent into the charcoal canister 9 via and the evaporated fuel is adsorbed in the activated carbon layer 10. Therefore, even at this time, the evaporated fuel does not flow into the outside air at all.

Next, the fuel cap 25 is removed to insert the fueling nozzle. At this time, the lower end opening of the fueling nozzle guide 26 is closed by the vaporized fuel outflow prevention valve 28. Fuel does not leak into the open air. Next, the fueling nozzle is inserted into the fueling nozzle guide 26, the evaporative fuel outflow prevention valve 28 is opened by the tip of the fueling nozzle 26, and fuel is supplied from the fueling nozzle into the fuel tank 8. The evaporated fuel generated at this time is adsorbed in the activated carbon layer 10 via the on-off valve 17 and the conduit 16. Therefore, also at this time, the evaporated fuel is not released into the outside air. Further, at this time, the purge control valve 14 is closed, so that the evaporated fuel is not sent into the intake passage 5.

When the fuel tank 8 is filled with fuel, the refueling nozzle is pulled out, the fuel cap 25 is attached, and the opening / closing lid 31 is closed. When the opening / closing lid 31 is closed, the opening / closing valve 17 is closed, and thus the fuel tank 8 is closed again. Charcoal canister 9 activated carbon layer 10
The vaporized fuel is adsorbed on the valve only when the on-off valve 17 is open, that is, when refueling. Of course, this activated carbon layer 10
Has a sufficient capacity to adsorb all the evaporated fuel fed to the activated carbon layer 10 during refueling.

FIG. 3 shows another embodiment. In this embodiment, the first cylindrical tank 6 in which the fuel tank is the lowest installed position
0, and the second cylindrical tank 61 with the highest installation position,
It is constituted by a third cylindrical tank 62 installed at an intermediate height position between these tanks 60 and 61. The bottom of the first cylindrical tank 60 is connected to the bottom of the second cylindrical tank 61 and the bottom of the third cylindrical tank 62 via corresponding conduits 63 and 64, respectively. The top of 60 and the top of the third cylindrical fuel tank 62 are connected to the head space of the second cylindrical tank 61 via corresponding conduits 65 and 66, respectively. Further, in this embodiment, the fuel supply pump 19 and the relief valve 20 are arranged in the first cylindrical tank 60, and the oil supply pipe 24 is connected to the first cylindrical tank 60. Furthermore, the top of the second cylindrical tank 61 is connected to the charcoal canister 9 via the ventilation control valve 16.

The embodiment shown in FIG. 3 is also controlled according to the routine shown in FIG. 2, and therefore each tank 60, 61,
The pressure in 62 becomes almost atmospheric pressure or more. In the embodiment shown in FIG. 3, the fuel tank is formed of three cylindrical tanks 60, 61, 62 which are advantageous in terms of strength so that they can sufficiently withstand high pressure in each tank 60, 61, 62. ing.

In this embodiment, for example, when the fuel supply pipe 24 is connected to the second cylindrical tank 61 and fuel is supplied to the second cylindrical tank 61, the fuel supplied to the second cylindrical tank 61 is supplied. Since it is immediately sent to the first cylindrical tank 60 and the second cylindrical tank 62, the liquid level of the fuel in the second cylindrical tank 61 does not rise easily. If the liquid level of the fuel does not rise easily, the fuel ejected from the refueling nozzle violently collides with the fuel accumulated on the inner wall surface of the tank or the bottom of the tank, and thus a large amount of evaporated fuel is generated.

On the other hand, as shown in FIG.
Is connected to the first cylindrical tank 60, fuel immediately accumulates in the first cylindrical tank 60 during refueling, so that the liquid level of the fuel rises into the refueling pipe 24 within a short time.
When the liquid level rises to the inside of the fuel supply pipe 24, the area of the fuel liquid level with which the fuel ejected from the fuel supply nozzle collides decreases, so the amount of evaporated fuel generated extremely decreases. Therefore, in the embodiment according to the present invention, the oil supply pipe 24 is connected to the inside of the first cylindrical tank 60 as shown in FIG. 3 in order to reduce the generation amount of the evaporated fuel at the time of refueling.

FIG. 4 and FIG. 5 show still another embodiment.
In this embodiment, as shown in FIG. 5, a pair of tank halves 70a, 70b are welded together to form a fuel tank 70 having three cylindrical tank chambers 71, 72, 73. Each cylindrical tank chamber 71, 7
As shown in FIG. 4, the fuel supply pumps 1 and 2 are disposed in the cylindrical tank chamber 73 located at the lowermost position.
9 and a relief valve 20 are arranged. Further, the oil supply pipe 24 is connected to the innermost cylindrical tank chamber 73, and the top of the uppermost cylindrical tank chamber 71 is connected to the charcoal canister 9 via the ventilation control valve 16. The uppermost cylindrical tank chamber 71 and the intermediate cylindrical tank chamber 72 are connected to each other through a pair of communication passages 74, and the intermediate cylindrical tank chamber 72 and the lowermost cylinder are connected to each other. The tank chamber 73 is connected to each other via a pair of communication passages 75.

Also in this embodiment, the oil supply pipe 24 is connected to the cylindrical tank chamber 73 located at the lowermost position, so that in this embodiment too, it is possible to prevent a large amount of evaporated fuel from being generated at the time of refueling. it can. Further, in this embodiment, since the fuel tank 70 is formed by welding the pair of tank halves 70a and 70b to each other, there is an advantage that the fuel tank 70 can be easily manufactured.

Although the ventilation control valve 16 is provided with the check valve 18 in any of the embodiments, the check valve 18 is not provided, that is, the ventilation control valve 16 is provided with only the opening / closing valve 17. When the pressure in the fuel tanks 8, 61, 70 is detected by the pressure sensor and the pressure in the fuel tanks 8, 61, 70 becomes negative, the on-off valve 17 is temporarily opened to open the fuel tanks. The pressure inside 8, 61, and 70 may be made almost atmospheric pressure.

[0028]

The vaporized fuel generated in the fuel tank can be completely prevented from flowing into the outside air.

[Brief description of drawings]

FIG. 1 is an overall view of a fuel processing device.

FIG. 2 is a flowchart showing a time interruption routine.

FIG. 3 is an overall view of another embodiment of the fuel processing device.

FIG. 4 is an overall view of yet another embodiment of the fuel processing device.

5 is a cross-sectional view of the fuel tank taken along line VV of FIG.

[Explanation of symbols]

 7 ... Fuel injection valve 8, 60, 61, 62, 70 ... Fuel tank 9 ... Charcoal canister 14 ... Purge control valve 16 ... Ventilation control valve 17 ... Open / close valve 18 ... Check valve 19 ... Fuel supply pump 24 ... Oil supply pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02M 37/00 C (72) Inventor Toshio Tanahashi 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. Within

Claims (3)

[Claims] 1. In a fuel processor in which vaporized fuel in a fuel tank is prevented from flowing out of the fuel tank except during fuel refueling, the upper space in the fuel tank is under negative pressure during refueling and in the fuel tank. A fuel processor for an internal combustion engine, which is connected to a charcoal canister through a ventilation control valve that opens when the engine is open. 2. A fuel supply passage for supplying fuel from the fuel tank to the fuel injection valve without providing a fuel return passage for returning excess fuel from the fuel injection valve into the fuel tank. A fuel processor for an internal combustion engine as set forth in. 3. The internal combustion engine according to claim 1, wherein the fuel tank is composed of a plurality of fuel tanks communicating with each other, and a fuel tank for fuel refueling is connected to a fuel tank having the lowest installation position among these fuel tanks. Fuel processor.