JP4638319B2 - Evaporative fuel emission suppression device for fuel tank - Google Patents

Description

The present invention includes a first evaporative fuel passage connecting the tank main body and the canister, a second evaporative fuel passage connecting the tank main body and a filler tube, and a differential pressure valve provided in the second evaporative fuel passage. The differential pressure valve relates to a fuel tank evaporative fuel discharge suppressing device having a throttle that always connects the fuel filler side and the tank body side .

  When supplying fuel to the filler tube from the fuel gun by opening the fuel filler port, the tank body and filler tube must be connected to prevent air from being sucked into the tank body from the fuel filler port. The fuel filler port is connected by an evaporative fuel passage, and part of the evaporated fuel pushed out of the tank body by the fuel supply is returned to the fuel filler port via the evaporative fuel passage, and this evaporated fuel is sucked by the fuel coming from the fuel gun. A device for preventing the suction of the atmosphere is known from Patent Document 1 below.

The evaporative fuel passage includes a differential pressure valve that opens when the tank main body side is higher than the intake port side by a predetermined value, and a throttle that is provided in the differential pressure valve and always communicates between the tank main body side and the intake port side. It has. When the flow rate of fuel coming out of the fuel gun is large, the suction force by the fuel is strong, so opening the differential pressure valve to return a large amount of evaporated fuel to the fuel filler port and sucking the evaporated fuel prevents air suction. When the flow rate of fuel coming out of the gun is small, the suction force by the fuel coming out of the fuel gun is weak, and the evaporated fuel returned to the fuel inlet cannot be sucked sufficiently. It is designed to prevent release to the atmosphere.
Japanese Patent No. 3536289

Incidentally, the internal space of the tank main body and held constant during the time the pressure was reduced by the intake negative pressure of the engine, it has been made to detect leakage of the tank body by monitoring the increase in between the internal pressure. In this case, if the lower end of the filler tube is submerged below the fuel level, the internal space of the tank body and the internal space of the filler tube communicate with each other via the throttle of the differential pressure valve, and the internal space of the tank body Even if the pressure is reduced, the internal space of the filler tube is not sufficiently reduced, and the air remaining in the internal space of the filler tube passes through the throttle and flows into the tank body while monitoring the internal pressure of the tank body. As a result, there is a possibility that the internal pressure gradually increases and a leak is generated.

  The present invention has been made in view of the above-described circumstances. When the leak of the tank body is detected using the intake negative pressure of the engine, the difference provided in the evaporative fuel passage connecting the tank body and the filler tube filler port is provided. The purpose is to prevent the pressure valve from becoming an obstacle.

To achieve the above object, according to the first aspect of the present invention, the first evaporative fuel passage connecting the tank body and the canister and the second evaporative fuel passage connecting the tank body and the filler port of the filler tube are connected. When, and a differential pressure valve disposed in the second fuel vapor passage, the vapor fuel discharge suppressing device for a fuel tank having said difference throttle valve is for communicating with the fuel supply port side and the tank main body side at all times, the differential pressure regulating valve is When fuel is supplied to the filler tube, a part of the evaporated fuel which is opened when the tank body side is higher than the fuel filler port side by a predetermined value or higher and is pushed out from the tank body is passed through the second evaporated fuel passage. together back to the fuel supply port, when the intake negative pressure of the engine is allowed to act on the tank body through the first evaporative fuel path for depressurizing the internal space of the tank body, the fuel supply port side tank main body Proposal remote predetermined value or more high-pressure vapor fuel discharge suppressing device for a fuel tank, characterized in that the inner space of the opening to the filler tube Ru 2-way valve der to reduce the pressure through the second evaporative fuel path when the Is done.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect, a fuel tank evaporative fuel emission suppressing device is proposed in which the throttle is formed in a valve body of a differential pressure valve. .

  According to the first aspect of the present invention, when fuel is supplied from the fuel gun to the filler tube by opening the fuel filler port, a part of the evaporated fuel in the tank body is in the second evaporated fuel passage when the fuel flow rate is large. It is possible to prevent air from being sucked into the tank main body from the fuel filler port by being pushed out through the differential pressure valve to the fuel filler port, sucked by the negative pressure generated by the fuel coming from the fuel gun, and returned to the tank body again.

  Since the negative pressure generated when the flow rate of fuel exiting the fuel gun is small, the evaporated fuel pushed out from the tank body through the second evaporated fuel passage to the fuel inlet cannot be returned to the tank body. Evaporated fuel may be released from the fuel filler into the atmosphere, but only a small amount of evaporated fuel that passes through the throttle of the closed differential pressure valve is pushed out to the filler, thereby preventing the evaporated fuel from being released into the atmosphere. be able to.

When the intake negative pressure of the engine is allowed to act on the tank body through the first evaporative fuel path to detect leaks of the tank body, it has the lower portion of the filler tube is separated from the gas phase space of the tank main body by the fuel level However, if the intake negative pressure is applied, the differential pressure valve opens and the throttle is invalidated, so that the internal space of the filler tube and the internal space of the tank body can be simultaneously decompressed to increase the accuracy of leak detection. .

  According to the configuration of the second aspect, since the throttle is formed on the valve body of the differential pressure valve, the structure of the differential pressure valve can be simplified.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  FIGS. 1 to 6 show an embodiment of the present invention. FIG. 1 is a diagram showing the overall configuration of a fuel tank evaporative fuel release suppression device (when refueling), and FIG. FIG. 3 is an enlarged sectional view of part 3 of FIG. 1, FIG. 4 is a sectional view taken along line 4-4 of FIG. 3, and FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 6 is an explanatory view of the operation of the differential pressure valve.

  As shown in FIGS. 1 and 2, the fuel tank T of an automobile opens and closes a tank body 11 that stores fuel, a filler tube 12 that extends obliquely upward from the tank body 11, and a fuel filler port 12 a at the upper end of the filler tube 12. A filler cap 13 that performs fuel supply, an in-tank type fuel pump 14 that supplies fuel from the tank body 11 to the engine E, and a first evaporative fuel passage 16 that connects the upper space of the tank body 11 to a canister 15 that adsorbs evaporated fuel. The second evaporative fuel passage 17 connecting the upper space of the tank main body 11 to the vicinity of the fuel filler opening 12a of the filler tube 12 and the differential pressure valve 18 provided in the second evaporative fuel passage 17 are provided. The canister 15 is connected to an intake passage 23 of the engine E via a third evaporated fuel passage 22, and a first on-off valve 19 is provided in the third evaporated fuel passage 22. A drain port 20 communicating with the atmosphere of the canister 15 is provided with a second on-off valve 21.

  In the portion where the first evaporative fuel passage 16 opens into the tank main body 11, a vent shut float valve 24 is provided that is closed by the fuel level that has risen when the tank is full and activates the auto-stop device of the fuel gun. Further, a portion where the branch passage 25 branched from the first evaporative fuel passage 16 opens into the tank body 11 is closed when the fuel tank T is largely inclined, and the fuel in the tank body 11 flows into the canister 15. A cut valve 26 is provided to prevent this. Further, the branch passage 25 is provided with a relief valve 27 that opens when the pressure on the tank body 11 side becomes higher than the pressure on the canister 15 side by a predetermined value or more.

  As shown in FIGS. 3 to 5, the differential pressure valve 18 has a two-way valve function, and includes a first valve member 32 and a second valve member 33 that are slidably supported by the valve housing 31. The second valve member 33 includes a disc-shaped valve body 33a and four first guide portions that protrude in the axial direction from one side surface of the valve body 33a and are slidably guided to the inner peripheral surface of the valve housing 31. 33b, four second guide portions 33c protruding in the axial direction from the other side surface of the valve body 33a, and a small-diameter restrictor 33d penetrating the center of the valve body 33a. The first valve member 32 is formed in the center of the disc-shaped valve body 32a and the four second guide portions 33c of the second valve body 33 so as to be slidable in the axial direction. Guide holes 32b and four notches 32c formed in the outer periphery of the valve body 32a. The first valve member 32 contacts the valve body 33a of the second valve member 33 with a first valve spring 34 disposed between the valve body 32a and the tip of the second guide portion 33c of the second valve member 33. It is energized in the direction of contact. The valve body 32 a of the first valve member 32 is a second valve spring 35 disposed between the valve seat 32 and the spring seat 31 a provided on the inner peripheral surface of the valve housing 31, and the valve seat provided on the inner peripheral surface of the valve housing 31. It is urged in the direction of sitting on 31b.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  As shown in FIG. 1, when the filler cap 13 is removed and the fuel supply gun 36 is inserted into the fuel supply port 12 a of the filler tube 12 and fuel is supplied, the fuel volume supplied from the fuel supply gun 36 to the tank body 11 is equivalent. A part of the evaporated fuel is returned to the vicinity of the fuel filler opening 12a from the second evaporated fuel passage 17 through the differential pressure valve 18. When the fuel supplied from the fuel gun 36 is at a high flow rate, the pressure on the upstream side of the differential pressure valve 18 is sufficiently higher than the atmospheric pressure on the downstream side. Therefore, as shown in FIG. The second valve member 33 and the first valve member 32 of the pressure valve 18 are integrally moved to the right while compressing the second valve spring 35, and the valve body 32 a of the first valve member 32 is moved from the valve seat 31 b of the valve housing 31. Separate.

  As a result, a large amount of evaporated fuel that has passed through the notch 32c of the valve body 32a of the first valve member 32 through the gap between the valve body 32a of the differential pressure valve 18 and the valve seat 31b that has been opened is filled from the tank body 11 side with the filler tube 12. It can flow to the fuel filler opening 12a side. At this time, a part of the evaporated fuel flows through the restriction 33d of the second valve member 33, but flows through the gap between the valve body 32a of the first and second valve members 32 and 33 and the valve seat 31b. The amount is very small compared to evaporative fuel. The evaporated fuel is sucked by the fuel exiting from the fuel gun 36 and returned to the tank body 11 from the filler tube 12, thereby preventing the atmosphere from being sucked from the fuel filler opening 12 a, and new evaporation in the tank body 11. Generation of fuel is suppressed.

  When the flow rate of the fuel supplied from the fuel gun 36 is low, the differential pressure on the upstream side and the downstream side of the differential pressure valve 18 becomes small. Therefore, as shown in FIG. The second valve member 33 and the first valve member 32 cannot move by the generated force. As a result, only a small amount of evaporated fuel that has passed through the throttle 33d of the valve element 33a of the closed differential pressure valve 18 flows from the tank main body 11 side to the filler opening 12a side of the filler tube 12, and is sucked by the fuel exiting from the fuel gun 36. Even if the force is small, it is possible to prevent the evaporated fuel that has been returned to the fuel filler opening 12a from being sucked into the tank main body 11 and released to the atmosphere.

  Now, when detecting leaks occurring in the tank body 11 and the filler tube 12, the second on-off valve 21 provided in the drain port 20 of the canister 15 is closed as shown in FIG. By opening the first on-off valve 19 provided in the passage 22, the inside of the tank body 11 is decompressed by the negative pressure of the intake passage 23. At this time, even if the lower end of the filler tube 12 is submerged below the fuel level and the communication between the internal space of the tank body 11 and the internal space of the filler tube 12 is blocked, the negative pressure of the intake passage 23 acts on the tank body 11. Then, as shown in FIG. 6C, the second valve member 33 of the differential pressure valve 18 moves to the left against the elastic force of the first valve spring 34, and the valve body 33a is moved to the first valve member. The air containing the evaporated fuel in the inner space of the filler tube 12 is separated from the valve body 32a of the first valve body 32 and between the valve bodies 32a and 33a of the first and second valve members 32 and 33. The air is quickly sucked into the internal space of the tank body 11 through the gap and the outer periphery of the valve body 33a, and the internal space of the tank body 11 and the internal space of the filler tube 12 are simultaneously decompressed. At this time, a part of the air is sucked through the throttle 33d of the second valve member 33, but the air sucked through the gap between the valve bodies 32a and 33a of the first and second valve members 32 and 33. It is a trace amount compared to.

  Subsequently, the tank body 11 is sealed by closing the first on-off valve 19 provided on the third evaporated fuel passage 22 while the second on-off valve 21 provided on the drain port 20 of the canister 15 is closed. Monitor the change in its internal pressure. As a result, if the internal pressure increases with time, it can be determined that a leak has occurred in the tank body 11, and if the internal pressure does not increase, it can be determined that no leak has occurred in the tank body 11.

  When the internal space of the tank main body 11 is depressurized by the intake negative pressure, there is no provision for the differential pressure valve 18 to open, and the air in the filler tube 12 is sucked into the tank main body 11 only through the throttle 33d. Then, monitoring of the internal pressure is started before the internal pressure of the filler tube 12 drops to the internal pressure of the tank body 11, and the air in the filler tube 12 gradually flows into the tank body 11 through the throttle 33d. As the internal pressure of the tank main body 11 increases, the tank main body 11 may be mistaken for a leak.

  On the other hand, according to this embodiment, when the internal space of the tank body 11 is reduced by the intake negative pressure, the differential pressure valve 18 is opened to reduce the internal pressure of the filler tube 12 to substantially the same as the internal pressure of the tank body 11. Therefore, the leak of the tank body 11 can be detected with high accuracy.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the structure of the differential pressure valve 18 is not limited to the embodiment, and a two-way valve having an arbitrary structure can be adopted as the differential pressure valve 18.

  In the embodiment, the throttle 33d is provided in the valve body 33a of the second valve member 33. However, the throttle can be provided at any position where the tank body 11 side and the fuel filler port 12a side of the differential pressure valve 18 communicate with each other. However, the structure of the differential pressure valve 18 can be simplified by providing the throttle 33d in the valve body 33a as in the embodiment.

The figure which shows the whole structure of the evaporative fuel emission suppression device of a fuel tank (at the time of fueling) Diagram showing the overall configuration of the evaporative fuel emission suppression device for the fuel tank (during a leak test) 3 is an enlarged sectional view of part 3 in FIG. Sectional view taken along line 4-4 in FIG. Sectional view along line 5-5 in FIG. Illustration of the action of the differential pressure valve

11 Tank body 12 Filler tube 12a Refueling port 15 Canister 16 First evaporative fuel passage 17 Second evaporative fuel passage 18 Differential pressure valve 33a Valve element 33d Restriction
E engine

Claims (2)

A first evaporative fuel passage (16) connecting the tank body (11) and the canister (15), and a second evaporative fuel passage (17) connecting the tank body (11) and the filler port (12a) of the filler tube (12). a), and a differential pressure valve provided in the second evaporative fuel path (17) (18), the differential pressure valve (18) is the fuel supply port (12a) side and the tank body (11) side an aperture for always communicated ( 33d) a fuel tank evaporative fuel emission suppressing device,
The differential pressure valve (18), when supplying fuel to the filler tube (12) includes a tank main body (11) side is opened to the tank body when the pressure over a predetermined value than the fuel supply port (12a) side ( 11) A part of the evaporated fuel pushed out from 11) is returned to the fuel filler port (12a) through the second evaporated fuel passage (17), and the intake negative pressure of the engine (E) is reduced in the first evaporated fuel passage (16). When the inner space of the tank body (11) is depressurized by acting on the tank body (11) through the valve body, the valve opening is opened when the oil filler (12a) side is higher than the tank body (11) side by a predetermined value or more. to vapor fuel discharge suppressing device for a fuel tank, characterized in that the inner space Ru 2-way valve der to reduce the pressure through the second evaporative fuel path (17) of the filler tube (12).   The evaporative fuel emission suppression device for a fuel tank according to claim 1, wherein the throttle (33d) is formed in a valve body (33a) of a differential pressure valve (18).

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