JP2001099015A - Evaporated fuel treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a device, improve mountability of an evaporated fuel treatment device, and suppress leakage of evaporated fuel by uniting functions of an inner pressure valve, an oil supply valve, and a bypass valve and thereby reducing number of pipings required for connecting the valves to each other. SOLUTION: A multifunction valve 3 is arranged on an evaporated fuel passage 2 connecting a fuel tank T to a canister 1. The multifunction valve 3 is so operated that a first diaphragm 41 is deformed due to difference between tank positive pressure introduced into a tank port 31 and pressure in a first chamber 4 for opening a first pipe port 34, and that a second diaphragm 51 is deformed due to difference between tank negative pressure introduced to a second chamber 5 through a first orifice 52 and pressure in a canister port 31 for opening a second pipe port 35. It is thus possible to keep pressure inside the fuel tank T at a specified value. At the time of oil supply and leak check, the second diaphragm 51 is deformed due to difference between the pressure in a canister port 32 introduced into the second chamber 5 and the pressure in the tank port 31, for opening the second pipe port 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor processing apparatus for collecting fuel vapor discharged from a fuel tank of an internal combustion engine.

[0002]

2. Description of the Related Art FIG. 7 shows a configuration of a conventional evaporative fuel processing apparatus. In the figure, T denotes a fuel tank, which communicates with a fuel supply port T1 via a fuel supply passage T2. A first passage 22 communicating with the canister 1 filled with activated carbon is connected to an upper wall of the fuel tank T, and an internal pressure valve 24 provided in the middle of the first passage 22 controls the internal pressure of the fuel tank T to a predetermined value. Kept in range. Further, the fuel tank T communicates with the canister 1 via a second passage 23 having a diameter larger than that of the first passage 22, and is opened at the connection end of the second passage 23 and the fuel tank T at the time of refueling. A refueling valve (ORVR valve) 25 is provided.

[0003] The internal pressure valve 2 is a two-way valve, which opens when the internal pressure of the fuel tank T exceeds a predetermined pressure and discharges evaporated fuel to the canister 1. Conversely, when the internal pressure of the fuel tank T falls below the predetermined pressure. Then, the evaporated fuel is sucked from the canister 1 together with the atmosphere. The refueling valve 25 is for complying with a refueling regulation (ORVR regulation) that regulates the release of evaporated fuel to the atmosphere during refueling. For example, a negative pressure passage 26 communicating with a refueling passage T2 near the refueling port T1. And the valve is opened by the negative pressure introduced from the negative pressure passage 26 during refueling. As a result, a large amount of fuel vapor generated at the time of refueling is discharged to the canister 1 through the large-diameter second passage 23, and the refueling port T
Prevents leakage from 1.

A first passage 22 and a second passage 23 are connected to one end of the canister 1 (upper end in the figure), and a purge passage 7 having a purge valve 71 is connected to the first passage 22 and the second passage 23. The purge passage 7 communicates with an intake passage of an engine (not shown).
When the valve 1 is opened, the atmosphere is introduced into the canister 1 by the engine negative pressure. With this atmosphere, the evaporated fuel is desorbed (purged) and sent to the intake passage of the engine, and the canister 1 is regenerated.

[0005] At the other end (lower end in the figure) of the canister 1 is connected an atmosphere introducing passage 8, which is provided with an electromagnetic valve 81.
And an atmosphere valve 82. The electromagnetic valve 81 is normally opened, and is driven to close when a leak check of the evaporation system is performed, thereby closing the evaporated fuel passage from the fuel tank T to the canister 1. The atmospheric valve 82 is a mechanical valve configured to close in a normal state and open with a differential pressure between the inside and the outside of the canister 1. While the valve is opened by the negative pressure in the canister 1 and the atmosphere is introduced into the canister 1 through the air filter 83.

The first passage 22 has a bypass passage 27 and a bypass valve 28 communicating the upstream and downstream of the internal pressure valve 24.
Is provided. The bypass valve 28 is an electromagnetically driven valve that closes in a normal state and is driven to open during a leak check to bypass the upstream side and the downstream side of the internal pressure valve 24.

[0007]

However, the above-described conventional fuel vapor treatment apparatus has a fuel tank T and a canister 1.
Between the first and second passages 22 and 23 and the bypass passage 27.
4. Since the refueling valve 25 and the bypass valve 28 are respectively provided, the device configuration is complicated. Further, pipes for connecting these valves to the fuel tank T or the canister 1 are required, and the fuel vapor is liable to leak from a connection portion of these pipes. Further, since a large number of pipes are required for connection, the space occupied by these pipes at the time of mounting on a vehicle becomes large, and there is a problem that the apparatus becomes large.

Therefore, an object of the present invention is to reduce the number of pipes required for connecting these valves by integrating the functions of an internal pressure valve, a fuel supply valve, and a bypass valve, and to suppress the leakage of fuel vapor. Another object of the present invention is to provide an evaporative fuel treatment apparatus in which the entire apparatus is reduced in size and the mountability is improved.

[0009]

According to a first aspect of the present invention, there is provided an evaporative fuel processing apparatus for guiding evaporative fuel generated in a fuel tank to a canister to adsorb and hold the evaporative fuel in a passage connecting the fuel tank and the canister. Is provided with a multifunctional valve having the following configuration. The multifunctional valve includes a tank port communicating with the fuel tank, a canister port communicating with the canister, a first communication port connecting these two ports, a second communication port having a larger diameter than the first communication port, and a communication port with the atmosphere. A first valve member that opens and closes the first communication port by a differential pressure between the first chamber and the tank port, a first valve member that opens and closes the tank port through a first orifice, and a first valve member that communicates with the canister port through a second orifice. Two chambers, a second valve member that opens and closes the second communication port by a differential pressure between the second chamber and the canister port or the tank port, and a third valve member that opens and closes the second orifice. When the fuel tank internal pressure exceeds a predetermined pressure, the first valve member is opened by the pressure difference between the tank positive pressure introduced into the tank port and the first chamber, and the first valve member is opened. Communication port Open, when said fuel tank pressure falls below a predetermined pressure, the first
By opening the second valve member and opening the second communication port by the pressure difference between the tank negative pressure introduced into the second chamber through the orifice and the canister port, the internal pressure of the fuel tank is increased. At the time of a leak check, the third valve member is opened to open the second orifice, and the pressure of the canister port introduced into the second chamber through the second orifice and The second valve member is opened by the pressure difference of the tank port to open the second communication port, and at the time of refueling, the third valve member is opened to open the second orifice. The second valve member is opened by a difference between the pressure of the second chamber and the pressure of the tank port to open the second communication port.

The multi-function valve opens the first communication port by the positive pressure in the fuel tank and discharges the fuel vapor from the tank port to the canister port, while releasing the second fuel by the negative pressure in the tank. The opening of the communication port is opened, and the atmosphere is introduced into the tank port through the canister port, and has a function as an internal pressure valve. Further, at the time of a leak check, the third valve member is opened to introduce an intake pipe negative pressure into the second chamber through the canister port, and the second pipe is opened due to a pressure difference from the tank port. The valve member is opened to bypass the canister port and the tank port. Further, at the time of refueling, the third valve member is opened, and the diameter of the fuel tank is larger than that of the first communication port due to the pressure difference between the pressure of the evaporated fuel generated in a large amount in the fuel tank and the pressure of the second chamber. Open the second communication port of the above,
A large amount of fuel vapor is delivered to the canister.

As described above, since the multifunctional valve has the functions of the internal pressure valve, the oil supply valve, and the bypass valve, the configuration of the device is simplified as compared with the conventional device in which each of these valves is separately provided. Therefore, the number of pipes can be reduced, and the leakage of fuel vapor from the connection pipes can be significantly reduced. Further, the size of the entire apparatus can be reduced and the mountability on a vehicle can be improved.

[0012] According to a second aspect of the present invention, the second chamber of the multifunction valve may be provided with a negative pressure introducing passage communicating with a fuel supply passage of the fuel tank. In this case, at the time of refueling, as described above, instead of opening the third valve member and the second valve member in two stages, the refueling negative pressure introduced through the negative pressure introduction passage and the refueling negative pressure The second valve member is opened by the pressure difference between the tank ports and the second valve member is opened.
Can be opened. The operation at the time of the leak check is the same. The third valve member is opened to open the second orifice, and the pressure of the canister port introduced into the second chamber and the pressure of the tank port are introduced. The second valve member is opened by the difference between the two to open the second passage.

According to the third aspect of the present invention, the first and the second
Are constituted by diaphragms constituting the chamber walls of the first chamber and the second chamber, respectively. Using a diaphragm type valve, these are disposed so as to partition between the first chamber and the second chamber and each of the ports, and are displaced by a pressure difference between both surfaces thereof, so that the first and second chambers are displaced. The above functions as the second valve member can be easily realized.

[0014] In the configuration of claim 4, the first and the second are described.
Is provided on the diaphragm constituting the second valve member. If the first and second orifices communicating the second chamber and the respective ports are provided in a diaphragm that partitions between the first and second ports, the above-described effects can be easily obtained with a simple configuration.

According to a fifth aspect of the present invention, the third valve member is an electromagnetic valve. Specifically, the third valve member can be an electromagnetic valve, and the second orifice can be quickly opened as needed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a view showing the entire configuration of the evaporative fuel processing apparatus, and a fuel tank T for storing fuel.
Has an oil supply passage T2 opening at the upper part of the side wall, and fuel is supplied from the oil supply port T1 via the oil supply passage T2. One end of an evaporated fuel passage 2 as a passage is connected to the upper wall of the fuel tank T, and the other end is connected to the canister 1. In the middle of the evaporative fuel passage 2,
A multi-function valve 3 having the functions of an internal pressure valve, a bypass valve, and a refueling valve (ORVR valve) is provided.

The canister 1 has a well-known configuration, and has an adsorption chamber filled with a fuel adsorbent such as activated carbon in a cylindrical container having both ends closed, and is connected to one end face (upper end face in the figure). The evaporative fuel introduced from the evaporative fuel passage 2 is temporarily absorbed and held. A purge passage 7 that communicates with an unillustrated engine intake pipe via an electromagnetically driven purge valve 71 is connected to one end face (the upper end face in the drawing), and is connected to the other end face (the lower end face in the drawing). Is connected to an atmosphere introduction passage 8 communicating with the atmosphere. When the purge valve 71 is opened during operation of the engine, a large amount of air is introduced into and adsorbed into the canister 1 through the air filter 83, the air valve 82, and the electromagnetic valve 81 provided in the air introduction passage 8 due to the suction pipe negative pressure. The evaporated fuel is desorbed (purged) and sent to the engine intake pipe.

The solenoid valve 81 provided in the atmosphere introduction passage 8
This is for performing a leak check of an evaporation system. The valve is normally opened, and the valve is driven to be closed during the leak check. The atmospheric valve 82 is a mechanical valve configured to close in a normal state and open with a differential pressure between the inside and outside of the canister 1. Release to the atmosphere while canister 1
The valve is opened by the internal negative pressure, and the atmosphere is introduced into the canister 1.

FIG. 1 shows details of the multi-function valve 3. In the figure, the multi-function valve 3 has a cylindrical main body housing H1 and a substantially container-like upper housing H2 and lower housing H3 arranged to cover the upper and lower openings thereof, respectively. The main body housing H1 has a tank port 31 projecting tubularly from the left side wall in the figure and connected to the fuel vapor passage 2 on the fuel tank T side, and a tubular port projecting from the right side wall and being connected to the vaporized fuel passage 2 on the canister 1 side. A canister port 32 is provided. A left end portion of the canister port 32 extends into the main body housing H1 to form a cylindrical portion 33 concentrically located therewith.
A first port 34 is formed as a communication port, and a second port 35 is formed at a lower end portion as a second communication port having a large diameter. A first diaphragm 41, which is a first valve member, and a second diaphragm 51, which is a second valve member, are disposed so as to cover the first port 34 and the second port 35.

The first diaphragm 41 has an outer peripheral edge sandwiched between the upper housing H2 and the main body housing H1, and a first chamber 4 between the upper housing H2 and the upper housing H2.
Is formed. The first diaphragm 41 constitutes a bottom wall of the first chamber 4 and is urged downward by a spring force of a first spring 42 disposed in the first chamber 4 so that a thick central portion is formed by the first pipe. It abuts the mouth 34 and closes it.
The first chamber 4 has an atmosphere hole 4 provided in the upper housing H2.
The atmosphere is introduced through 3
The upper surface of the diaphragm 41 receives the atmospheric pressure, and the outer peripheral portion of the lower surface receives the pressure in the tank port 31. When the pressure of the tank port 31, that is, the positive pressure in the fuel tank T exceeds a predetermined value, the first diaphragm 41 is displaced upward against the pressing force of the first spring 42, and the first port 34
To release.

The outer periphery of the second diaphragm 51 is sandwiched between the main housing H1 and the lower housing H3, and the second diaphragm 51 is located between the lower housing H3 and the lower housing H3.
Is formed. The second diaphragm 51 constitutes an upper wall of the second chamber 5, and a thick central portion abuts and closes the second pipe port 35, and the second diaphragm 51 is provided on the outer peripheral portion in the form of a rubber film.
It has a small-diameter first orifice 52 that communicates the chamber 5 with the tank port 31. In addition, the second diaphragm 51
, A second orifice 53 having a larger diameter than the first orifice 52 is formed. The opening and closing of the second orifice 53 is performed by an electromagnetic valve section 6 which is a third valve member disposed below the second orifice 53.

Since the first orifice 52 is normally open, it is necessary to reduce the diameter so that the pressure in the second chamber 5 and the pressure in the tank port 31 do not immediately become equal through the first orifice 52. Second orifice 53
Since is opened and closed by the electromagnetic valve section 6, pressure may be introduced immediately after being opened. That is, the diameter may be larger than the first orifice 52.

The electromagnetic valve section 6 includes a moving core 61 that is urged upward by a spring force of a second spring 62 to close the second orifice 53, and an electromagnetic drive section that drives the moving core 61 to open. The moving core 61
A leaf spring member coated with rubber is fixed to the upper end edge of the cylindrical body, and this upper end surface seals the second orifice 53. The electromagnetic drive unit includes a moving core 61
, A coil 64 wound around the outer periphery thereof, a yoke 65, and a magnetic plate 66 as magnetic path constituent members, and the electromagnetic force generated by energizing the coil 63. Then, the moving core 61 is sucked and opened.

The second spring 62 is connected to the solenoid valve portion 6.
Is pressed against the second orifice 53, and at the same time, the second diaphragm 51 on which the second orifice 53 is formed is urged in the valve closing direction to close the second pipe port 35. The second spring 62 is supported by a piece 67 fixed on the upper part of the stator core 61, and a rubber projection 68 is provided on an opposing surface of the moving core 61 to absorb an impact caused by a collision with the piece 67 when the moving core 61 is lowered. Is provided.

In a normal state in which the coil 63 is not energized, the second orifice 53 is closed by the moving core 61, and the second chamber is in communication with the tank port 31 by the first orifice 52. Second diaphragm 5
Numeral 1 indicates the pressure of the canister port 32 at the center of the upper surface and the pressure of the tank port 31 at the lower surface, and the pressure of the tank port 31, that is, the internal pressure of the fuel tank T becomes a negative pressure. When the pressure exceeds a predetermined value, the second diaphragm 51 is displaced downward against the pressing force of the second spring 62 to open the second port 35.

When the coil 63 is energized, the moving core 61 is attracted, the second orifice 53 is opened, and the pressure of the canister port 32 is introduced into the second chamber through the second orifice 53. At this time, the second diaphragm 51 receives the pressure of the tank port 31 on the outer periphery of the upper surface and the pressure of the canister port 32 on the lower surface. When the pressure of the tank port 31 exceeds the pressure of the canister port 32, the second diaphragm 51 receives the second diaphragm 51. 51 is displaced downward to open the second port 35.

Incidentally, on the upper wall of the main body housing H1,
The pressure sensor S is fixed so that the internal pressure can be detected at the time of a leak check of the evaporation system. Further, the main housing H1 and the upper housing H2
The lower housing H3 and the lower housing H3 are attached by ultrasonic welding, respectively, to prevent water from entering the inside.
Similarly, the attachment of the member after winding the coil to the electromagnetic valve portion 6 is also performed by ultrasonic welding to prevent water from entering.

Next, the operation of the fuel vapor processing apparatus having the structure shown in FIGS. 1 and 2 will be described with reference to FIGS. (When the fuel tank internal pressure is positive pressure) In FIG. 1, the pressure in the tank port 31 is equal to the internal pressure in the fuel tank T, and the pressure in the first chamber 4 above the first diaphragm is large through the atmosphere hole 43. It is equal to the atmospheric pressure. At normal times when the internal pressure of the fuel tank T is within a predetermined range, the first diaphragm 41 is pressed against the first pipe port 34 by the spring force of the first spring 42, and the space between the tank port 31 and the canister port 32 is shut off. I have. Here, when the temperature of the fuel tank T becomes high due to the rise of the outside temperature, the evaporation of the fuel becomes active and the internal pressure of the fuel tank T rises. When the positive pressure of the fuel tank T exceeds a predetermined pressure, the first diaphragm 41 is deformed against the spring force of the first spring 42 due to the differential pressure between the positive pressure of the tank port 31 and the atmospheric pressure of the first chamber 4. Then, it is separated from the first port 34 (FIG. 3A). As a result, the tank port 31 communicates with the canister port 32, and as a result, the evaporated fuel is introduced into the canister 1, and the internal pressure of the fuel tank T is maintained at a predetermined pressure or less.

(When the internal pressure of the fuel tank is a negative pressure (at the time of back purge)) When the internal pressure of the fuel tank T is within a predetermined range and the coil 64 of the electromagnetic valve section 6 is not energized normally, the spring force of the second spring 62 The moving core 61 is pressed by the second orifice, and the second diaphragm 51 is pressed by the second pipe port 35, so that the tank port 31 and the canister port 32 are shut off. The pressure in the second chamber 5 below the second diaphragm 51 is equal to the pressure in the first orifice 52.
Through the tank port 31 and is equal to
The pressure at canister port 32 is approximately equal to the pressure of canister 1 at approximately atmospheric pressure.

Here, the fuel tank T
When the temperature of the fuel tank T decreases, the evaporated fuel condenses, and the internal pressure of the fuel tank T decreases. The second through the first orifice 52
When the negative pressure of the fuel tank T introduced into the chamber 5 exceeds a predetermined pressure, the pressure of the canister port 32 at atmospheric pressure and the pressure of the second chamber 5
The second diaphragm 51 is deformed against the spring force of the second spring 52 and moves away from the second port 35 (FIG. 3B). As a result, the tank port 31 and the canister port 32 communicate with each other. As a result, the atmosphere is introduced into the fuel tank T via the atmosphere introduction path 8 and the canister 1, and the internal pressure of the fuel tank T is maintained at a predetermined pressure or higher.
At this time, the evaporated fuel desorbed by the atmosphere introduced into the canister 1 is returned to the fuel tank T (back purge).

(At the time of leak check) At the time of a leak check of the evaporation system, the coil 64 of the electromagnetic valve portion 6 is energized to attract the moving core 61 to the stator core 63 to open the second orifice 53. At the time of the leak check, the internal pressure of the canister 1 is reduced to a negative pressure by closing the electromagnetic valve 81 of the atmosphere introduction path 8 and opening the purge valve 71 of the purge passage 7, and the second orifice 53
, A negative pressure is introduced into the second chamber 5 from the canister port 32 side. When the internal pressure of the fuel tank T, that is, the pressure on the tank port 31 side exceeds the pressure in the second chamber 5, the second diaphragm 51 is deformed and moves away from the second pipe 35. As a result, the tank port 31 and the canister port 32 communicate with each other, and a negative pressure is introduced from the canister 1 into the fuel tank T (FIG. 3A). Thereafter, the purge valve 71 is closed, and the pressure sensor S detects pressure fluctuations in the evaporative fuel passage from the purge valve 71 to the fuel tank T via the canister 1, so that the presence or absence of leakage in the evaporative fuel passage can be detected. .

(At the time of refueling) At the time of refueling, for example,
The refueling signal is output when the refueling port 11 is opened by attaching a reed switch to 1. Upon receiving this refueling signal, the coil 64 of the solenoid valve section 6 is energized,
The moving core 61 is attracted to the stator core 63 and the second
Orifice 53 is opened. At the time of refueling, the pressure of the canister 1 is almost atmospheric pressure, and the inside of the second chamber 5 is
It is almost equal to the atmospheric pressure through the canister port 32. When refueling is performed, the pressure in the fuel tank T increases with an increase in the amount of fuel.
When the pressure of the second chamber 5 rises and exceeds the pressure in the second chamber 5, the second
The diaphragm 51 is deformed and separates from the second port 35. As a result, the tank port 31 and the canister port 32 communicate with each other, and a large amount of fuel vapor generated in the fuel tank T is introduced into the canister 1 through the large-diameter second pipe port 35.

FIGS. 5 and 6 show a second embodiment of the present invention. In the first embodiment, at the time of refueling,
The orifice 53 is opened by using the reed switch and the solenoid valve unit 6 attached to the valve. However, the second pipe port 35 can be opened by using the negative oil pressure without operating the solenoid valve unit 6. . In the present embodiment, as shown in FIG. 5, a negative pressure inlet 54 is provided in the bottom wall of the second chamber 5 of the multi-function valve 3. As shown in FIG. 6, the negative pressure introduction port 54 is connected to the negative pressure path 21 communicating with the fuel supply passage 12 near the fuel supply port 11 of the fuel tank T.

At the time of refueling, the refueling port T1 is connected to the refueling passage T2.
A negative pressure is generated by the fuel flow flowing into the second chamber 4, and the negative pressure is introduced into the second chamber 4 through the negative pressure path 21. On the other hand, the pressure in the fuel tank T increases with refueling. When the pressure difference between the pressure in the tank port 31 communicating with the fuel tank T and the pressure in the second chamber 5 exceeds a predetermined pressing force of the second spring 62, the second diaphragm 51 is deformed, and the second diaphragm 51 is deformed. 2 Separate from the port 35. Also in this case, the tank port 31 and the canister port 32 can communicate with each other, and a large amount of fuel vapor generated in the fuel tank T can be introduced into the canister 1 through the large-diameter second pipe port 35. The operation other than the refueling operation is the same as in the first embodiment.

As described above, according to the present invention, the internal pressure valve,
By providing the multifunctional valve 3 having the functions of the bypass valve and the refueling valve (ORVR valve) integrated, the device configuration can be simplified, the number of connection pipes can be reduced, and the leakage of fuel vapor can be reduced. . Further, by integrating functions, the number of pipes and the number of parts can be reduced, the entire apparatus can be reduced in size, and the mountability can be improved.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention and is an overall sectional view of a multi-function valve of an evaporative fuel treatment device.

FIG. 2 is an overall configuration diagram of an evaporative fuel processing apparatus for an internal combustion engine according to the first embodiment of the present invention.

3A and 3B are diagrams for explaining the operation of the multi-function valve, and FIG.
FIG. 4B is a schematic diagram of the multi-function valve when the fuel tank internal pressure is a positive pressure, and FIG.

4A and 4B are diagrams for explaining the operation of the multi-function valve, and FIG.
FIG. 3B is a schematic view of the multi-function valve at the time of leak check, and FIG.

FIG. 5 shows the second embodiment of the present invention and is an overall cross-sectional view of a multi-function valve of the fuel vapor treatment device.

FIG. 6 is an overall configuration diagram of an evaporative fuel processing apparatus for an internal combustion engine according to a second embodiment of the present invention.

FIG. 7 is an overall configuration diagram of a conventional fuel vapor treatment device for an internal combustion engine.

[Explanation of symbols]

 T fuel tank T1 fuel supply port T2 fuel supply passage 1 canister 2 evaporative fuel passage (passage) 21 negative pressure passage 3 multifunctional valve 31 tank port 32 canister port 33 solenoid valve 34 first pipe port (first communication port) 35 second Pipe port (second communication port) 4 First chamber 41 First diaphragm (first valve member) 42 First spring 5 Second chamber 51 Second diaphragm (second valve member) 52 First orifice 53 First 2 orifice 54 negative pressure introduction port 6 solenoid valve (third valve member) 61 moving core 62 second spring 7 purge passage 71 purge valve 8 atmosphere introduction path 81 solenoid valve 82 atmosphere valve 83 air filter

Claims (5)

[Claims] 1. An evaporative fuel processing device for guiding an evaporative fuel generated in a fuel tank to a canister for adsorption and collection,
A tank port provided in the middle of a passage connecting the fuel tank and the canister, and communicating with the fuel tank;
A canister port communicating with the canister, a first communication port connecting these two ports and a second communication port having a larger diameter than the canister port, and a first chamber communicating with the atmosphere and a pressure difference between the tank port and the first port. A first valve member that opens and closes a communication port of the tank;
A second chamber that communicates with the canister port through an orifice; a second valve member that opens and closes the second communication port by a differential pressure between the second chamber and the canister port or the tank port; A multi-function valve having a third valve member for opening and closing the orifice, wherein the multi-function valve allows the tank positive pressure introduced into the tank port and the first pressure when the fuel tank internal pressure exceeds a predetermined pressure. The first valve member is opened by the pressure difference with the chamber to open the first communication port, and when the fuel tank internal pressure falls below a predetermined pressure, the first orifice communicates with the second chamber through the first orifice. The second valve member is opened by the pressure difference between the introduced tank negative pressure and the canister port to open the second communication port, thereby keeping the internal pressure of the fuel tank at a predetermined pressure, and In some cases, the third valve member is opened to open the second orifice, and the difference between the pressure of the canister port and the pressure of the tank port introduced into the second chamber through the second orifice. The second valve member is opened to open the second communication port. At the time of refueling, the third valve member is opened to open the second orifice, and the pressure in the second chamber is increased. An evaporative fuel processing device, wherein the second valve member is opened by a difference in pressure between the first and second tank ports to open the second communication port. 2. A negative pressure introduction passage communicating with a fuel supply passage of the fuel tank is provided in the second chamber, and at the time of refueling, a difference between a fuel supply negative pressure introduced through the negative pressure introduction passage and a pressure of the tank port. The second valve member is opened by the
When the leak is checked, the third valve member is opened to open the second orifice, and the pressure of the canister port and the pressure of the tank port introduced into the second chamber are opened. 2. The evaporative fuel treatment apparatus according to claim 1, wherein the second valve member is opened to open the second communication port due to the difference. 3. The evaporative fuel treatment apparatus according to claim 1, wherein the first and second valve members are diaphragms forming chamber walls of the first chamber and the second chamber, respectively. 4. The diaphragm according to claim 3, wherein said first and second orifices are provided on a diaphragm constituting said second valve member.
The evaporative fuel treatment device according to any one of the preceding claims. 5. The evaporative fuel treatment apparatus according to claim 1, wherein the third valve member is an electromagnetic valve.