JP3175464B2 - Fuel processor 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 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, and this pressurized air passage is connected to a fuel tank. The pressure inside the fuel tank is maintained at a positive pressure by guiding the pressurized air discharged from the machine into the pressurized air passage and the fuel tank, and allowing some of the pressurized air to flow out from the atmosphere opening hole. An internal combustion engine is known (Japanese Patent Application Laid-Open No. 54-151727).
Reference). In this internal combustion engine, pressurized air continues to flow out of the open air hole during operation of the engine, so that dust in the outside air can be prevented 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 outside through the atmosphere opening hole, Thus, there is a problem of causing air pollution.

[0004]

According to a first aspect of the present invention, a charcoal canister having an evaporative fuel chamber formed on one side of an activated carbon layer is supplied at the time of fuel supply.
Charcoal to adsorb only evaporated fuel
Only a canister is provided, connecting the evaporative fuel chamber on the one hand to the engine intake passage via a purge control valve and on the other hand to the upper space of the fuel tank via a vent control valve, and the vent control valves are connected in parallel. An on-off valve arranged, and a check valve that can only flow from the evaporative fuel chamber toward the inside of the fuel tank, and when the ignition switch is turned off, the purge control valve is closed, and the ignition switch is turned off. And open the on-off valve when refueling ,
When the ignition switch is off and the fuel
Only when oil is used, the fuel vapor in the fuel tank is
Into the charcoal canister.
Activated carbon layers are all
It has sufficient capacity to adsorb evaporative fuel and
The fuel vapor should be purged after the option switch is turned on.
The purge control valve is opened and the fuel supply
Evaporated fuel adsorbed on the activated carbon layer during oiling
So that it can be purged.

In the second invention, in the first invention,
The tip of the fuel tank filler pipe is formed on the vehicle body.
The opening and closing lid that can close this recess.
Equipped with the ignition switch off and open
The on-off valve is opened when the lid is opened
You.

[0006]

According to the third aspect, the fuel according to the first aspect,
The tank consists of a plurality of fuel tanks communicating with each other,
Of these fuel tanks, the fuel tank with the lowest
The fuel supply pipe is connected to the fuel tank.

[0007]

[0008]

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, Reference numeral 9 denotes a charcoal canister. The charcoal canister 9 has an activated carbon layer 10 therein.
Atmospheric chamber 11 and evaporative fuel chamber 12 open to the atmosphere on both sides of
Are provided. The evaporative fuel chamber 12 is connected on the one hand to the intake passage 5 downstream of the throttle valve 6 via a purge conduit 13 and a purge control valve 14, and on the other hand to the upper space of the fuel tank 8 via a conduit 15 and a ventilation control valve 16. 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 disposed at the bottom in the fuel tank 8, and a discharge port of the fuel supply pump 19 has a reservoir 22 through a relief valve 20 and a fuel supply conduit 21 disposed in the fuel tank 8.
Linked to The reservoirs 22 are connected to the fuel injection valves 7 of the respective cylinders via respective conduits 23.

A fuel cap 25 is removably attached to the tip of a 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, an evaporative fuel outflow prevention valve 28 rotatable around a pivot 27 and normally closing a lower end opening of a refueling nozzle guide 26 as shown in FIG. Is arranged. 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 mounted on the vehicle body 29 so as to be rotatable around a pivot 32. . Further, a detection switch 33 for engaging with the opening / closing lid 31 and detecting that the opening / closing lid 31 is opened is attached to the vehicle body 29.

The electronic control unit 40 is composed of a digital computer, and a ROM (read only memory) 42, a RAM (random access memory) 43, a CPU (microprocessor) 44, and an input port 45 interconnected 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. An input signal of the detection switch 33 and the ignition switch 3 are input to the input port 45.
5 is input. On the other hand, the output port 46 is connected to the purge control valve 14, the on-off valve 17, and the fuel supply pump 19 via a corresponding drive circuit 48, respectively.

Next, the operation of the fuel processor shown in FIG. 1 will be described with reference to a time interruption routine shown in FIG. In the embodiment shown in FIG. 1, power is supplied to the electronic control unit 40 even when the ignition switch 35 is turned off. Referring to FIG. 2, first, at step 50, it is determined whether or not 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 fed into the reservoir 22 via the relief valve 20 and the fuel supply conduit 21. When the fuel pressure becomes equal to or higher than the set pressure, the relief valve 20 opens to discharge the surplus fuel again into the fuel tank 8, so that the fuel pressure in the reservoir 22 is maintained at a 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 into the reservoir 22, particularly the fuel supplied to the fuel injection valve 7, is heated by the heat generated by the engine, so that the temperature of the fuel becomes high. In this case, when the high-temperature fuel is returned to the fuel tank 8 through the fuel return conduit, the fuel temperature in the fuel tank 8 rises, so that 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 amount of evaporated fuel generated in the fuel tank 8 is reduced since hot fuel is not returned to the fuel tank 8. You can do it.

Returning to FIG. 2, when the fuel supply pump 19 is driven in step 51, the routine proceeds to step 52, where it is determined whether or not conditions for purging the fuel vapor in the intake passage 5 are satisfied. For example, when it is determined that the engine cooling water temperature has become equal to or higher than a predetermined set temperature and the engine has been warmed up, it is determined that the condition for purging is satisfied. When the purge condition is not satisfied purge control valve 14 is made to close valve proceeds to step 53. On the other hand, when the purge condition is satisfied, the routine proceeds to step 54, where the purge control valve 14 is opened, and at this time, the fuel vapor adsorbed on the activated carbon layer 10 of the charcoal canister 9 is removed by the activated carbon layer 10 And is purged into the intake passage 5 through the purge conduit 13.

On the other hand, when it is determined in step 50 that the ignition switch 35 is off, the routine proceeds to step 55, where the purge control valve 14 is closed.
Next, the routine proceeds to step 56, where the fuel supply pump 19 is stopped. Next, at step 57, the detection switch 3
It is determined whether 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, when the open / close lid 31 is closed as described above, the open / close valve 17 is closed. When the pressure in the fuel tank 8 is higher than the atmospheric pressure, the check valve 18 is closed.
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 completely shut off from the outside air. This is the same when the ignition switch 35 is turned on and the fuel supply pump 19 is operated. Thus, at this time, the fuel vapor in the fuel tank 8 is not released into the outside air at all.

On the other hand, when the pressure in the fuel tank 8 becomes lower than the atmospheric pressure, that is, when the pressure in the fuel tank 8 becomes a negative pressure, the check valve 18 opens so that the pressure in the fuel tank 8 becomes almost atmospheric pressure. Thereby, the deformation of the fuel tank 8 is prevented. By providing such a check valve 18, the pressure in the fuel tank 8 is always substantially higher than the atmospheric pressure. When the check valve 18 is opened, the evaporated fuel released from the activated carbon layer 10 of the charcoal canister 9 is sent into the fuel tank 8 via the conduit 16 and the check valve 18. Therefore, also at this time, the fuel vapor 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 to refuel, the detection switch 33 is turned on. Therefore, at this time, the process proceeds from step 57 to step 59 in FIG.
Is opened. When the on-off valve 17 is opened, the fuel vapor in the fuel tank 8 is released from the on-off valve 17 and the conduit 15.
And the fuel is sent into the charcoal canister 9 and the evaporated fuel is adsorbed in the activated carbon layer 10. Therefore, also at this time, the fuel vapor does not flow out into the outside air at all.

Next, the fuel cap 25 is removed to insert the refueling nozzle. At this time, the lower end opening of the refueling nozzle guide 26 is closed by the evaporative fuel outflow prevention valve 28. Fuel does not flow into the outside air. Next, the refueling nozzle is inserted into the refueling nozzle guide 26, the evaporated fuel outflow prevention valve 28 is opened by the tip of the refueling nozzle 26, and the fuel is supplied from the refueling nozzle into the fuel tank 8. The fuel vapor 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 fuel vapor is not released into the outside air. Further, at this time, since the purge control valve 14 is closed, no evaporated fuel is sent into the intake passage 5.

When the fuel tank 8 is filled with fuel, the fueling 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, so that the fuel tank 8 is closed again. Activated carbon layer 10 of charcoal canister 9
The fuel is adsorbed only when the on-off valve 17 is opened, that is, only when refueling. Of course, this activated carbon layer 10
Has sufficient capacity to adsorb all evaporated fuel sent to the activated carbon layer 10 during refueling.

FIG. 3 shows another embodiment. In this embodiment, the fuel tank is the first cylindrical tank 6 at the lowest position.
0, the second cylindrical tank 61 having the highest installation position,
A third cylindrical tank 62 is provided at an intermediate height 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 upper space of the second cylindrical tank 61 via corresponding conduits 65 and 66, respectively. In this embodiment, the fuel supply pump 19 and the relief valve 20 are arranged in the first cylindrical tank 60, and the fuel supply pipe 24 is connected to the first cylindrical tank 60. Further, 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.
The pressure in 62 is approximately above atmospheric pressure. In the embodiment shown in FIG. 3, the fuel tank is formed of three cylindrical tanks 60, 61, and 62, which are advantageous in strength, so that they can sufficiently withstand the high pressure in each of the tanks 60, 61, and 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 the fuel is immediately sent to the first cylindrical tank 60 and the third cylindrical tank 62, the liquid level of the fuel in the second cylindrical tank 61 does not easily rise. If the fuel level does not rise easily, the fuel ejected from the refueling nozzle violently collides with the fuel stored on the inner wall surface of the tank or the bottom of the tank, and thus a large amount of fuel vapor is generated.

On the other hand, as shown in FIG.
Is connected to the first cylindrical tank 60, the fuel is immediately stored in the first cylindrical tank 60 at the time of refueling, and the liquid level of the fuel rises to the inside of the refueling pipe 24 in 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 that the amount of fuel vapor generated decreases extremely. Therefore, in the embodiment according to the present invention, the fuel supply pipe 24 is connected to the inside of the first cylindrical tank 60 as shown in FIG.

FIGS. 4 and 5 show still another embodiment.
In this embodiment, as shown in FIG. 5, a fuel tank 70 having three cylindrical tank chambers 71, 72, 73 is formed by welding a pair of tank halves 70a, 70b to each other. Each cylindrical tank chamber 71, 7
As shown in FIG. 4, the fuel supply pumps 1 and 2 are disposed in the lowermost cylindrical tank chamber 73.
9 and a relief valve 20 are arranged. The oil supply pipe 24 is connected to the lowermost 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. Further, 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 cylindrical tank chamber 72 are connected to each other. The tank chamber 73 is connected to each other through a pair of communication passages 75.

Also in this embodiment, the fuel supply pipe 24 is connected to the cylindrical tank chamber 73 located at the lowermost position. Therefore, also in this embodiment, it is possible to prevent a large amount of fuel vapor from being generated at the time of fuel supply. 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 manufacture of the fuel tank 70 is easy.

In each of the embodiments, the ventilation control valve 16 is provided with the check valve 18, but the check valve 18 is not provided, that is, the ventilation control valve 16 is provided with only the opening / closing valve 17. The pressure in the fuel tanks 8, 61, 70 is detected by a pressure sensor, and when the pressure in the fuel tanks 8, 61, 70 becomes a negative pressure, the on-off valve 17 is temporarily opened to open the fuel tank. The pressure in 8, 61 and 70 may be set to substantially the atmospheric pressure.

[0028]

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

[Brief description of the drawings]

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

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

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

FIG. 4 is an overall view of still another embodiment of the fuel processing apparatus.

FIG. 5 is a sectional view of the fuel tank taken along line VV in FIG. 4;

[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 on-off valve 18 check valve 19 fuel supply pump 24 fuel supply pipe

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshio Tanahashi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-61-191427 (JP, A) JP-A-61-124423 (JP, A) JP-A 1-158228 (JP, U) JP-A 2-125816 (JP, U) JP-A 64-16924 (JP, U) (58) Fields surveyed (Int. Cl. ⁷⁾ , DB name) B60K 15/00-15/04 F02M 37/00

Claims (3)

(57) [Claims] 1. A charcoal canister having an evaporative fuel chamber formed on one side of an activated carbon layer , which is fed during fueling.
Charcoal canister to adsorb only evaporated fuel
Only provided, connected to the upper space of the fuel tank via the vent control valve, on the other hand as well as connected to the engine intake passage via the purge control valve is in one of the evaporation fuel chamber,
An open / close valve in which the ventilation control valve is arranged in parallel, and a check valve that can only flow from the fuel vapor chamber to the inside of the fuel tank, and closes the purge control valve when the ignition switch is turned off. When the ignition switch is off and the fuel is refueled, the on-off valve is opened ,
When the ignition switch is off and the fuel
Only when oil is used, the fuel vapor in the fuel tank is
Into the charcoal canister.
Activated carbon layers are all
It has sufficient capacity to adsorb evaporative fuel and
The fuel vapor should be purged after the option switch is turned on.
The purge control valve is opened and the fuel supply
Evaporated fuel adsorbed on the activated carbon layer during oiling
A fuel processing apparatus for an internal combustion engine, which is configured to purge the fuel. 2. A vehicle body comprising : a fuel tank;
Protrude into the recess formed on the
With an open / close lid, and the ignition switch is turned off.
And the on-off valve is opened when the on-off lid is opened
The fuel processing system for an internal combustion engine according to claim 1 adapted to give. 3. The internal combustion engine according to claim 1, wherein the fuel tank comprises a plurality of fuel tanks communicating with each other, and a fuel supply pipe is connected to the fuel tank having the lowest installation position among the fuel tanks. Fuel processor.