JPH06249086A - Fuel vapor processor - Google Patents

Abstract

PURPOSE:To dispense with a bypass pipe and bypass valve by setting one of a plurality of check valves to the opened condition while an atmosphere release closing valve is closed and a purge controlling valve is opened. CONSTITUTION:A purge system consisting of first-fourth vapor pipes 3, 5, 9, 14, a plurality of check valves 45, 49, 53, a canister 6 and purge controlling valve 11 is provided between the upper part of a fuel tank 2 and an intake pipe 13 of an engine 12. Further, an atmosphere release switch valve 8 for opening and closing an atmosphere release port of the canister 6 is additionally attached to the canister 6 and an internal pressure sensor 17 is additionally attached to the fuel tank 2 to detect abnormalities in the device according to a change in a pressure signal from the internal pressure sensor 17. Particularly, one check valve 53 of a plurality of check valves 45, 49, 53 is opened while an atmosphere switch closing valve 8 is closed and a purge controlling valve 11 is opened. Bypass valves like a solenoid valve or the like can be omitted only by providing a plurality of check valves 45, 49, 53.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fuel vapor processing apparatus having an abnormality detecting means.

[0002]

2. Description of the Related Art FIG. 4 is a principle diagram of a conventional fuel vapor processing apparatus. The fuel vapor processing apparatus is an apparatus for preventing fuel vapor in a fuel tank 101 from leaking to the atmosphere. When the pressure of the steam generated in the sealed fuel tank 101 reaches a set value, the positive pressure valve 103 of the two-way valve 102 is opened, and the fuel steam is transferred to the canister 108 via the vapor pipes 105 and 106.
It is absorbed by the activated carbon 109 (arrow ■). Intake pipe 110
The fuel accumulated in the canister 108 due to the negative pressure of
Is sucked into the intake pipe 110 via the and reaches the combustion chamber of the engine 112. When the fuel tank 101 is cooled at night and the internal pressure of the fuel tank becomes a negative pressure exceeding a predetermined value, the two-way valve 1
The negative pressure valve 104 of 02 opens, and the fuel in the canister 108 returns to the fuel tank 101 as shown by arrow 2 along with the outside air of arrow 2.

The positive pressure valve 103 of the two-way valve 102 is set so as not to open due to a pressure increase associated with refueling which is carried out on a daily basis. Thus, the two-way valve 102 has the spring 1
Due to the action of 03a and 104a, the fuel tank 102 and the canister 108 are both closed as long as the set pressure is not exceeded.

However, if the vapor pipe is damaged or comes off due to some cause, there is a disadvantage that the fuel vapor is released to the atmosphere. A countermeasure against this is taken in JP-A-4-153535.

FIG. 5 is a principle diagram of a conventional fuel vapor processing apparatus having an abnormality detecting means. In the apparatus shown in FIG. 4, a bypass pipe 121 and a bypass valve 122 for bypassing the two-way valve 102, and a canister 108 are provided. The canister atmosphere open / close valve 123 for opening and closing the atmosphere passage of the fuel tank 1.
An internal pressure sensor 124 for measuring the internal pressure of 01 and a control unit 125 for appropriately opening and closing the bypass valve 122 and the canister atmosphere open / close valve 123 based on the signal of the internal pressure sensor 124 are added. Reference numerals 103 to 112 are applied to FIG. In the above configuration, the bypass valve 12
2 is opened and the canister atmosphere open / close valve 123 is closed, the intake pipe 110 is made to have a negative pressure.
5, 106, 111, canister 108, bypass pipe 1
21 and the fuel tank 101 become negative pressure.

If there is a fine hole (for example, 0.04 inch diameter) somewhere in the above system, the atmosphere intrudes through the hole and a predetermined negative pressure cannot be obtained. This is measured by the internal pressure sensor 124. In addition, since neither the positive pressure valve 103 nor the negative pressure valve 104 of the two-way valve 102 is opened at the time of abnormality detection, the bypass pipe 121 is provided. During normal times other than the abnormality detection, the bypass valve 122 is closed, and the canister atmosphere open / close valve 123 is opened to have the same configuration as in FIG.

[0007]

[Problems to be Solved by the Invention] As described above,
A conventional abnormality detection mechanism requires a bypass pipe and a bypass valve, and a space for accommodating them. Therefore, an object of the present invention is to omit the bypass pipe and the bypass valve in the fuel vapor processing device equipped with the abnormality detection mechanism.

[0008]

In order to achieve the above object, the present invention provides a first vapor pipe, a plurality of check valves, a second vapor pipe, between an upper portion of a fuel tank and an intake pipe of an engine.
A purge system consisting of a canister, a third vapor pipe, a purge control valve and a fourth vapor pipe is arranged in this order, and an atmosphere release stop valve for opening and closing the atmosphere release port of the canister is attached to the canister so that the internal pressure of the fuel tank is increased. Attach a sensor,
A fuel vapor processing apparatus having an abnormality detecting means for detecting an abnormality of a fuel vapor processing apparatus according to a change in a pressure signal from the internal pressure sensor, wherein one check valve among the plurality of check valves is It is a check valve that is opened when the atmosphere open / close valve is closed and the purge control valve is open.

[0009]

Function Normally, the fuel vapor is sent from the fuel tank to the intake pipe via the canister or returned to the fuel tank (fuel vapor processing function). When detecting an abnormality in the purge system, the canister atmosphere open / close valve is closed and the change in the pressure signal from the internal pressure sensor is monitored to detect the abnormality.

Therefore, by providing only a plurality of check valves, a bypass valve such as a solenoid valve can be eliminated.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of the reference numerals.
FIG. 1 is a principle diagram of a fuel vapor processing apparatus having an abnormality detecting means of the present invention. The fuel vapor processing apparatus 1 includes a fuel tank 2
The first vapor pipe 3, the three-way valve 4, the second vapor pipe 5, the canister 6, the canister atmosphere open / close valve 8, the third vapor pipe 9, the purge control valve 11 and the intake pipe of the engine 12 extending from the upper part of the A purge system including a fourth vapor pipe 14 connected to the fuel tank 13, an internal pressure sensor 17 attached to the fuel tank 2, and a control unit 18.

FIG. 2 is a structural principle diagram of the three-way valve of the present invention. The three-way valve 4 has a diaphragm 4 inside a valve box 41.
2, a first check valve 4 including a spring 43 and a valve element 44
5, a second check valve 49 including a spring 47 and a valve element 48, and a third check valve including a spring 51 and a valve element 52.
The check valve 53 and three valves 44, 49, 53 are housed. The valve box 41 can be appropriately disassembled at a location not shown so that the valves 44, 49 and 53 can be incorporated.

The first check valve 45 is a check valve which allows only the flow from the first vapor pipe 3 to the second vapor pipe 5,
Moreover, the pressure of the first vapor pipe 2 on the fuel tank side is, for example, 20.
The diaphragm 42 and the spring 43 are set so that the valve element 44 moves in the opening direction at mmHg. The second check valve 49 is a check valve that allows only the flow from the second vapor pipe 5 to the first vapor pipe 3, and the first check valve on the fuel tank side.
The spring 47 is set so as to start opening when the pressure of the vapor pipe 3 becomes a negative pressure below a predetermined value. The third check valve 53 is a check valve that allows only the flow from the first vapor pipe 3 to the second vapor pipe 5, and the pressure of the first vapor pipe 3 on the fuel tank side starts to open at, for example, 50 mmHg. The spring 51 is set.

When the second vapor pipe 5 is under negative pressure, the first check valve 45 and the second check valve 49 are both valve bodies 44,
It is closed because 48 is sucked in the closing direction. On the other hand, the valve element 52 of the third check valve 53 is biased in the opening direction when the second vapor pipe 5 has a negative pressure. Therefore,
Only the third check valve 53 has the first vapor pipe 3 of 50 mmH.
When g is exceeded, and when the second vapor pipe 5 has a negative pressure below a certain level, it opens.

The operation of the fuel vapor processing apparatus having the above structure will be described below. In FIG. 1, the canister atmosphere open / close valve 8 and the purge control valve 11 are normally open. When the pressure of the steam generated in the closed fuel tank 2 reaches a set value, the first check valve 45 of the three-way valve 4 opens, and the fuel steam is transferred to the canister 6 via the first and second vapor pipes 3 and 5. Is absorbed by the activated carbon 6a (arrow 2). Due to the negative pressure in the intake pipe 13, the fuel accumulated in the canister 6 is sucked into the intake pipe 13 through the third and fourth vapor pipes 9 and 14 together with the outside air (arrow ■) as shown by the arrow {circle around (4)}. To the combustion chamber. When the fuel tank 2 is cooled at night and the internal pressure of the fuel tank becomes a negative pressure exceeding a predetermined value, the second check valve 49 of the three-way valve 4 is opened, and the fuel in the canister 6 is fueled by the outside air indicated by the arrow (2) as indicated by the arrow (2). Return to tank 2. The above is the fuel vapor processing function that is always performed.

When checking the presence or absence of abnormality in the vapor system, the canister atmosphere open / close valve 8 is closed by a command from the control unit 18. Since the intake pipe 13 has a negative pressure, the fourth vapor pipe 14, the third vapor pipe 9, the canister 8, and the second vapor pipe 5 have a negative pressure, and the second vapor pipe 5 has a negative pressure.
The check valve 53 opens, and the first vapor pipe 3 and the fuel tank 2
Also becomes negative pressure. The internal pressure sensor 17 monitors the pressure drop state and sends a signal to the control unit. If a predetermined drop rate is not obtained, the control unit 18 determines that there is an abnormality such as perforation and sends an abnormal signal. Emit. This is the abnormality detecting means.

It is important to detect the state where the intake negative pressure of the engine 12 is stable as a condition for detecting abnormality. For example, if the intake pressure sensor 63 provided downstream of the throttle valve 61 in FIG. 1 is used to check a change in intake pressure and the intake pressure does not change for a predetermined time or more, or
A stable intake negative pressure is obtained when the change in the opening of the throttle valve 61 (monitored by the valve opening sensor 62) does not change by a predetermined value or more in a predetermined vehicle speed or higher such as high-speed cruising. To be If the engine operating condition is such that a stable intake negative pressure is obtained, the third check valve is reliably opened in a short time, and the intake negative pressure is sufficiently introduced into the fuel tank 2.

When the internal pressure of the fuel tank detected by the internal pressure sensor 17 becomes a negative pressure below a certain level, the controller 18 promptly closes the purge control valve 11 to protect the fuel tank 2. Further, since the canister atmosphere open / close valve 8 is normally open and the second vapor pipe 5 is at almost atmospheric pressure, the third check valve 53 will not open due to negative pressure during normal operation. Therefore, by adopting the above three-way valve 4, the conventional bypass pipe and bypass valve can be omitted.

FIG. 3 is another embodiment of the three-way valve according to the present invention, in which the second check valve 49 and the third check valve 53 have the same structure as that of FIG. 2, but the first check valve 55 is The spring 56 and the valve body 57, that is, the third check valve 53 has the same configuration. However, the first check valve 55
Has the same specifications as the first check valve 45 in FIG.
Since the diaphragm is not used, the structure of the three-way valve is simplified.

[0020]

As described above, according to the present invention, a plurality of check valves are provided in the purge system, and one of the check valves is purged while the canister atmospheric release valve is closed. Since the check valve is opened when the valve is open, a bypass valve such as a conventional bypass pipe or a solenoid valve is not required, and the layout of the fuel vapor processing apparatus is facilitated.

[Brief description of drawings]

FIG. 1 is a principle diagram of a fuel vapor processing apparatus provided with an abnormality detecting means of the present invention.

FIG. 2 is a structural principle diagram of a three-way valve of the present invention.

FIG. 3 shows another embodiment of the three-way valve according to the present invention.

FIG. 4 is a principle diagram of a conventional fuel vapor processing apparatus.

FIG. 5 is a principle diagram of a conventional fuel vapor processing apparatus equipped with an abnormality detecting means.

[Explanation of Codes] 1 ... Fuel vapor treatment device, 2 ... Fuel tank, 3 ... First vapor pipe, 4 ... 3-way valve, 5 ... Second vapor pipe, 6 ... Canister, 8 ... Canister atmosphere open / close valve, 9 ... third vapor pipe, 11 ... purge control valve, 12 ... engine, 13 ... intake pipe, 14 ... fourth vapor pipe, 17 ... internal pressure sensor, 18 ... control section, 41 ... valve box, 45 ... first check valve, 49 ... Second
Check valve, 53 ... Third check valve (one check valve).

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[Procedure amendment]

[Submission date] March 15, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art FIG. 4 is a principle diagram of a conventional fuel vapor processing apparatus. The fuel vapor processing apparatus is an apparatus for preventing fuel vapor in a fuel tank 101 from leaking to the atmosphere. When the pressure of the steam generated in the sealed fuel tank 101 reaches a set value, the positive pressure valve 103 of the two-way valve 102 is opened, and the fuel steam is transferred to the canister 108 via the vapor pipes 105 and 106.
Is absorbed by the activated carbon 109 (arrow). Intake pipe 110
Due to the negative pressure of the fuel, the fuel accumulated in the canister 108 is transferred to the vapor pipe 111 as indicated by the arrow together with the outside air (arrow).
Is sucked into the intake pipe 110 via the and reaches the combustion chamber of the engine 112. When the fuel tank 101 is cooled at night and the internal pressure of the fuel tank becomes a negative pressure exceeding a predetermined value, the two-way valve 1
The negative pressure valve 104 of 02 opens, and the fuel in the canister 108 returns to the fuel tank 101 as indicated by the arrow together with the outside air indicated by the arrow.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

The operation of the fuel vapor processing apparatus having the above structure will be described below. In FIG. 1, the canister atmosphere open / close valve 8 and the purge control valve 11 are normally open. When the pressure of the steam generated in the closed fuel tank 2 reaches a set value, the first check valve 45 of the three-way valve 4 opens, and the fuel steam is transferred to the canister 6 via the first and second vapor pipes 3 and 5. Is absorbed by the activated carbon 6a (arrow). Due to the negative pressure of the intake pipe 13, the fuel accumulated in the canister 6 is sucked into the intake pipe 13 through the third and fourth vapor pipes 9 and 14 together with the outside air (arrow) as shown by the arrows, and the combustion chamber of the engine 12 To When the fuel tank 2 is cooled at night and the internal pressure of the fuel tank becomes a negative pressure exceeding a predetermined value, the second check valve 49 of the three-way valve 4 is opened, and the fuel in the canister 6 is supplied with the outside air indicated by the arrow as shown by the arrow. Go back. The above is the fuel vapor processing function that is always performed.

Claims (1)

[Claims] 1. A first vapor pipe, a plurality of check valves, a second vapor pipe, a canister, a third vapor pipe, a purge control valve, and a fourth vapor pipe between the upper portion of the fuel tank and the intake pipe of the engine. The purge system is arranged in this order, and the atmosphere opening / closing valve for opening / closing the atmosphere opening port of the canister is attached to the canister, the internal pressure sensor is attached to the fuel tank, and the pressure signal from the internal pressure sensor is changed according to the change. A fuel vapor processing apparatus having an abnormality detecting means for detecting an abnormality of the fuel vapor processing apparatus, wherein one check valve among the plurality of check valves has the atmosphere open / close valve closed and A fuel vapor processing apparatus, which is a check valve that is opened when the purge control valve is open.