JPH06346802A - Evaporation fuel loss preventing device for vehicle - Google Patents

Abstract

PURPOSE:To prevent deterioration of activated carbon in a steam absorption chamber by preventing liquid fuel from flowing into the steam absorption chamber even if a purge control valve is not opened by its failure. CONSTITUTION:Out of evaporation fuel generated in a fuel tank, high boiling point cut and liquid component thereof are recovered in a fuel reservoir chamber 23, and only gas component is absorbed on activated carbons in a steam adsorption chamber 22. When adsorbent fuel is separated, intake negative pressure is led in from a first purge passage 24, and steam adsorbed on the activated carbon in the steam adsorption chamber 22 is discharged in an intake air system. The intake negative pressure is led into the bottom part of the fuel reservoir chamber 23 through a second purge passage 31a, and cumulated liquid fuel is discharged into the intake system. The purge amount in a second pure passage 31a is suppressed to a low level by a throttle 37.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel loss prevention device for a vehicle such as an automobile equipped with an internal combustion engine that uses a volatile fuel such as gasoline.

[0002]

2. Description of the Related Art The fuel flowing into a fuel vapor collector is separated into a liquid component and a gas component so that only the gas component is adsorbed by an adsorbent to prevent the adsorbent from deteriorating and desorbing the fuel vapor. A fuel vapor collection device has been proposed which prevents liquid fuel from being mixed from a fuel source at the time of separation and can maintain high performance for a long time (Japanese Utility Model Publication No. 61-70558).

As shown in FIGS. 4 and 5, this apparatus comprises a fuel vapor collection tank 1 for adsorbing and collecting fuel vapor, a vapor adsorption chamber 2 containing a fuel vapor adsorbent such as activated carbon, and gas-liquid separation. Room 3
And a U-shaped liquid fuel introduction pipe 6 connected to the fuel introduction passage 16 and provided with a float valve 9 inside thereof is erected in the gas-liquid separation chamber 3, and the vapor intake chamber 2 and the gas-liquid separation The separation chamber 3 is connected to the separation chamber 3 by the adsorption pipes 4 above them, and the liquid fuel introduction pipe 6 in the gas-liquid separation chamber 3 is connected to the float valve 9
Is connected to the vapor discharge port 13 of the vapor adsorption chamber 2 through the desorption pipe 12, and when the liquid fuel does not exist in the gas-liquid separation chamber 3, the float valve 9 separates the liquid fuel introduction pipe 6 from the liquid fuel introduction pipe 6. It is configured so as to cut off the communication between the working pipes 12.

Reference numeral 8 is a fuel hole provided in the peripheral wall of one of the U-shaped pipes of the liquid fuel introducing pipe. The float valve 9 is housed inside the one pipe 7, and an orifice 10 closed by the float valve 9 is provided at the base portion thereof.

The check ball valve 5 provided in the adsorption pipe 4 opens when the vapor pressure generated in the fuel tank or the carburetor exceeds a certain level. Reference numeral 15 is a solenoid valve provided in the desorption pipe 12, which is closed when the engine is stopped so that fuel is not pushed out into the intake system by the fuel vapor pressure. Reference numeral 17 is an air introduction port provided at the bottom of the vapor adsorption chamber 2.

[0006]

SUMMARY OF THE INVENTION In the above conventional technique,
If the solenoid valve 15 for purge control malfunctions and remains closed, the liquefied fuel easily flows to the vapor adsorption chamber 2 side and deteriorates the adsorbent such as activated carbon. Further, there is a problem that fuel vapor flows out from the air introduction port and pollutes the air.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vehicle fuel loss prevention device capable of solving such problems.

[0008]

In order to achieve the above object, in the first aspect of the invention, a canister (21) is provided with a vapor adsorption chamber (22) containing a fuel vapor adsorbent and a tank communication passage (24). A fuel storage chamber (23) is provided between the fuel storage chamber (23) and a second purge passage (31) which communicates with the lower portion of the fuel storage chamber (23) where the intake negative pressure of the engine is applied when the throttle valve opens a predetermined opening. Provided.

According to a second aspect of the invention, in the first aspect of the invention, a throttle (37) is provided in the second purge passage (31) provided in the intake pipe. A third aspect of the invention contains an adsorbent (39) that adsorbs liquid fuel in the fuel storage chamber (23) of the first aspect.

In a fourth aspect of the invention, an adsorbent (39) for adsorbing liquid fuel is contained in the fuel storage chamber (23) of the first aspect.

[0011]

[Function] Of the fuel generated in the fuel tank and introduced into the canister, the high boiling point fraction and the liquid components are stored in the fuel storage chamber (2
3), and only the gas component is adsorbed by the fuel vapor adsorbent in the vapor adsorption chamber (22). When desorbing the adsorbed fuel,
Negative pressure is introduced and vapor in the adsorbent is released into the intake system, and negative intake pressure is introduced into the lower part of the fuel storage chamber (23) through the second purge passage (31), and the fuel storage chamber The liquid fuel in (23) is discharged into the intake system.

The throttle (37) of the second purge passage (31)
Reduces the purge amount in the second purge passage, that is, the purge amount not controlled by the ECU. Fuel sump (23)
The adsorbent (39) for adsorbing the liquid fuel stored in (1) prevents the liquid fuel from scattering when the canister (21) is damaged due to a vehicle collision or the like.

The fins for heat conversion provided in the tank communication passage in the canister (21) easily cool the fuel vapor introduced from the fuel tank into a liquid state. Further, since the second purge passage (31) communicates with the place where the engine intake negative pressure is applied when the throttle valve (30) opens a predetermined opening, the negative pressure when the throttle valve is closed is small, and the throttle valve is closed. When is open, the negative pressure increases. Therefore, the amount of fuel flowing through the second purge passage (31) has a characteristic substantially proportional to the amount of intake air of the engine.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment of the present invention shown in FIGS. 1 and 2, reference numeral 21 in FIG. 2 is a canister, which is a vapor adsorption chamber 22 containing a fuel evaporative adsorbent such as activated carbon as shown in FIG. Fuel storage chamber 23 for storing liquid fuel and tank communication passage 24
And the auxiliary adsorption chamber 25.

The lower end of the auxiliary adsorption chamber 25 opens in the middle of the tank communication passage 24, and the upper end opening, that is, the first purge passage 26, passes through the purge control valve 27 of FIG.
The intake pipe 29 of No. 8 is connected downstream of the throttle valve 30.

Reference numeral 31 denotes a second purge passage communicating from a lower portion of the fuel storage chamber 23 of the canister 21 to a second purge port 32 provided immediately upstream of the throttle valve 30 of the intake pipe 29, which is formed in the canister 21. The second purge passage 31a and the second purge passage 31a
Second purge passage 31b communicating with the purge port 32 of
It consists of and.

The tank communication passage 24 communicating with the lower portion of the vapor adsorption chamber 22 of the canister 21 is connected to the upper portion of the fuel tank 33. The atmosphere communication passage 34 communicating with the upper portion of the vapor adsorption chamber 22 is connected to the upstream side of the throttle valve 30 of the intake pipe 29 via the atmosphere control valve 35.

Reference numeral 36 is a well-known ECU, which is a purge control valve 27.
The air control valve 35 is operated to control the purge amount in the first purge passage 26, thereby controlling the air-fuel ratio of the air-fuel mixture supplied to the engine 28 to an optimum value.

Reference numeral 37 is a throttle provided in the second purge passage 31, 38 is a one-way valve provided in the second purge passage 31a of the canister 21, 39 is a metal sintered body or a fibrous adsorption for adsorbing liquid gasoline. It is a liquid fuel adsorbent composed of an agent and is contained in the inlet of the fuel reservoir chamber 23, that is, the opening facing the tank communication passage 24.

In the first embodiment, the fuel vapor generated from the fuel tank 33 when the vehicle is stopped flows into the canister 21 through the tank communication passage, the high boiling point fraction and the liquid component are separated, and the fuel pool chamber 23 is filled. It is adsorbed by the liquid fuel adsorbent 39. When the amount of the adsorbed liquid fuel increases, the liquid fuel drops and accumulates at the bottom of the fuel storage chamber 23.

The gas component enters the vapor adsorption chamber 22 and is once adsorbed by the adsorbent such as activated carbon. ECU 3 while the vehicle is traveling
6, the purge control valve 27 and the atmosphere control valve 35 are opened,
Moreover, the intake pipe negative pressure is introduced into the canister 21 through the first purge passage 26. As a result, air is introduced into the vapor adsorption chamber 22 from the atmosphere communication passage 35, and HC or the like adsorbed by the adsorbent such as activated carbon is purged.

Further, the negative pressure of the intake pipe is introduced from the second purge port 32 to the bottom of the fuel reservoir chamber 23 through the second purge passages 31b and 31a to purge the liquid fuel.
The second purge port 32 opens immediately upstream of the throttle valve 30 when the throttle valve 30 is fully closed and has a light load. When the throttle valve 30 is slightly opened, the second purge port 32 faces the throttle valve 30 as shown in the drawing, and It is located downstream of the throttle valve when the load is high.

Therefore, when the load is light, the throttle valve is closed and atmospheric pressure is applied to the second purge port 32, so that the amount of purge in the second purge passage is reduced. When the load is high, the throttle valve is wide open, and the negative pressure of the intake pipe sufficiently acts on the second purge port 32, so that the purge amount increases and the liquid component in the fuel reservoir chamber 23 is purged.

As described above, the amount of the liquid component purged through the second purge passage 31 is small when the load is light,
By increasing the amount at high load, changes in the air-fuel ratio in the air-fuel mixture supplied to the engine are reduced.

The throttle 3 provided in the second purge passage 31
7 reduces the vapor flow rate through the second purge passage 31. This reduces the amount of vapor that is not controlled by the ECU 36 and improves the vapor control performance.
The vapor flow rate through the second purge passage 31 is set to about 1/100 of the first purge flow rate, and by doing so, when the purge control valve 27 fails and does not open, the liquid fuel is removed. The liquid phase is prevented from entering the second purge port 32.

Activated carbon is contained in the auxiliary adsorption chamber 25, and when purging, the atmosphere (air) is mixed and gently changed so that the rich raw gas from the fuel tank 33 does not suddenly flow to the engine. In this way, the air-fuel ratio control is facilitated.

The liquid fuel adsorbent 39 accommodated in the fuel storage chamber 23 adsorbs the liquid gasoline, and prevents the liquid gasoline from scattering even if the canister 21 is damaged due to a vehicle collision or the like.

FIG. 3 shows a second embodiment of the present invention, which is shown in FIGS.
The same reference numerals as in the first embodiment of FIG.
The description is omitted. Also, connection to the intake pipe, ECU,
Each control valve and the like are the same as those in the first embodiment.

In the second embodiment, a large number of heat exchange fins 40 are provided in the tank communication passage 24 of the canister 1. The fins 40 are formed on both the inner wall and the outer wall of the canister 21 in a protruding manner, and are alternately inserted into the fins formed on the inner wall to improve heat exchange.

The fins 40 tend to cool the fuel flowing from the fuel tank 33 to become liquid. When the vehicle is parked, the temperature of the fuel tank is lower than the temperature of the engine room where the canister 21 is installed due to the influence of geothermal heat.
Therefore, the evaporated fuel from the fuel tank 33 is
The first fin 40 effectively cools and liquefies.

Reference numeral 41 denotes a float valve provided in the fuel storage chamber 23. When the liquid fuel is stored, it floats as shown in the figure to open the second purge passage. Normally, there is no liquid fuel, so
The float valve 41 is in the lowered position and is closed.

By doing so, the liquid fuel is stored in the fuel storage chamber 2
When it is not accumulated in 3, the float valve 41 is closed and the purging from the second purge passage 31 is stopped. Then, since the purging is performed only in the first purging passage 26, the purge flow rate can be accurately controlled by the purging control valve 27.

The second purge passage 31 is not limited to be in communication with the second purge port 32 shown in FIG. 1, but may be connected to the intake manifold of the engine.

[0034]

Since the vehicular evaporated fuel loss prevention apparatus of the present invention is constructed as described above, the purge control valve (2
Even if 7) fails and cannot be opened, the liquid fuel does not easily flow to the side of the vapor adsorption chamber (22), so there is no risk of deterioration of the adsorbent in the vapor adsorption chamber (22), and there is little air pollution.

Further, a throttle (3
Since 7) is provided, when the purge control valve (27) fails, the liquid fuel in the fuel pool (23) is not sucked into the liquid intake pipe.

Further, since the adsorbent (39) for adsorbing the liquid fuel is contained in the fuel storage chamber (23), the liquid fuel does not scatter when the canister (21) is damaged due to a vehicle collision or the like.

Furthermore, since the fins (40) for heat exchange are provided in the tank communication passage (24) in the canister (21), the evaporated fuel from the fuel tank is cooled and easily liquefied.

[Brief description of drawings]

FIG. 1 is an overall system diagram of a first embodiment of the present invention.

FIG. 2 is a vertical sectional front view of a canister according to the first embodiment of the present invention.

FIG. 3 is a vertical sectional front view of a canister according to a second embodiment of the present invention.

FIG. 4 is a vertical sectional front view of a conventional technique.

FIG. 5 is a plan view of the same.

[Explanation of symbols]

 21 canister 22 vapor adsorption chamber 23 fuel reservoir chamber 24 communication passage 31 purge passage 37 throttle 39 adsorbent 40 fins for heat exchange

Claims (4)

[Claims] 1. A vapor adsorption chamber (22) containing a fuel vapor adsorbent of a canister (21) and a tank communication passage (24).
A fuel storage chamber (23) is provided between the fuel storage chamber (23) and a lower portion of the fuel storage chamber (23), which communicates with a location where negative pressure of intake air of the engine is applied when the throttle valve opens a predetermined opening.
Evaporative fuel loss prevention device for vehicles provided with a purge passage (31). 2. A second purge passage (3) provided in the intake pipe.
The vehicular evaporated fuel loss prevention device according to claim 1, wherein a throttle (37) is provided in (1). 3. The vehicular evaporated fuel loss prevention device according to claim 1, wherein an adsorbent (39) for adsorbing the liquid fuel is contained in the fuel storage chamber (23). 4. The fin (40) for heat exchange is provided in the tank communication passage (24) in the canister (21).
Evaporative fuel loss prevention device for vehicles.