JPS6393625A - Fuel flow-out preventing device - Google Patents

Abstract

PURPOSE:To certainly prevent the flow-out of fuel when a fuel tank it titled, by arranging a float in shiftable ways in the vertical direction for a casing for the communication to a vent tube and arranging an outer cylindrical body in shiftable ways in the vertical direction for the casing and the float. CONSTITUTION:When the fuel liquid surface rises because of the tilt, etc. of a fuel tank 3, a float 7 rises, and a valve projector 10 seals a valve seat 8, and the horizontal stepped part 11 seals a subvalve seat 9, and the flow-out of fuel into a vent tube 1 is suppressed in two stages. When the fuel tank 3 is tilted by 90 deg., an outer cylindrical body 14 shifts in the direction crossing at right angles with the axis line of a casing 6, in other words, in the direction of gravity, and the float 7 is pressed in the valve sealing direction by the inclined surface effect between the tapered surface 16 of the outer cylindrical body 14 and the tapered surface 13 of the float 7. When the fuel tank 3 is turned down, the tapered surface 16 of the outer cylindrical body 14 presses the tapered surface 13 of the float 7 in the axial direction, and the float 7 is shifted in the valve sealing direction.

Description

[Detailed description of the invention] [Industrial application field]

This invention is a fuel leakage prevention system that effectively prevents fuel from flowing out of a fuel tank without installing a gas-liquid separator or associated complicated piping in an evaporative emission loss control system for a vehicle. Regarding equipment.

[Prior art and its problems]

The fuel tank usually has an injection pipe leading to the filler cassop, a fuel supply pipe to supply fuel to the engine, a fuel return pipe to return fuel not consumed by the engine, and to avoid pressure fluctuations in the fuel tank. A vent tube is connected to provide continuity between the inside of the tank and the outside of the tank. The vent tube is usually connected to a charcoal canister. In a charcoal canister, depending on the static pressure inside the engine's intake manifold, activated carbon adsorbs the gasoline component of the evaporative gas led from the vent tube and releases only clean air into the atmosphere, or the evaporative gas is sent to the intake manifold. It can be introduced and used for combustion. Furthermore, depending on the type of vehicle, the vent tube may simply be open to the atmosphere. By the way, the fuel injection pipe, fuel supply pipe, and fuel return pipe mentioned above are all water and airtight, so fuel will not leak from them, but the vent tube is ultimately open to the atmosphere, so if If fuel were to enter this interior, it could flow to the canister and render it inoperable, or it could leak from the open end of the canister or vent tube. Therefore, a gas-liquid separator is placed at the connection between the vent tube and the fuel tank to prevent the fuel in the tank from flowing into the vent tube even if the vehicle or fuel tank is tilted. Common. However, the above-mentioned gas-liquid separator itself has a relatively complex structure and is expensive, and it is necessary to connect the tank and the gas-liquid separator with multiple pipes, making it difficult to install it in a vehicle. This will cause an increase in costs. For this reason, recently, as shown in Japanese Utility Model Application Publication No. 58-106227, a fuel outflow device that has a simple structure that does not use a gas-liquid separator but can prevent fuel outflow into the vent tube has been developed. Proposed. The fuel outflow prevention device disclosed in the above publication has a float movable up and down in a valve chamber that has a discharge hole connected to a vent tube at the top, and has a valve protrusion on the top surface that can seal the discharge hole. On the other hand, a tapered part is provided in the lower part of the valve chamber, the diameter of which decreases as it goes downward, and a liquid passage hole is formed, and a steel ball is loosely installed in this tapered part. When the fuel liquid level rises, the float rises and its valve element closes the discharge hole, and when the fuel tank rolls over, the steel ball rolls on the tapered part due to gravity and pushes the float laterally to close the discharge hole, When the fuel tank falls over, the steel ball overcomes its buoyancy and directly pushes down the float, thereby sealing the discharge hole. As a result, even if the vehicle is tilted and the fuel level approaches the vent tube, or the vehicle rolls over or falls over, the valve prongs of the float will close the discharge hole at the top of the valve chamber, allowing fuel to flow out. from flowing into the vent tube. However, the fuel spill prevention device with the above structure requires water-resistant and gasoline-resistant steel balls such as stainless steel balls, which are still expensive, resulting in a high overall cost. Since the float and the steel balls are arranged in a vertically stacked manner, the valve chamber must also be vertically bulky, and there is a problem in that there is a limit to the weight reduction. The object of this invention is to solve the above-mentioned conventional problems and provide a fuel spill prevention device that does not use expensive steel balls, has a simpler structure, and can be further downsized. do.

[Means to solve the problem]

In order to solve the above problem, the present invention takes the following technical measures. In other words, the fuel spill prevention device of the present invention has an end portion of a vent tube that is fixed through the upper plate of the fuel tank, and a valve seat that is connected to the end portion of the vent tube so as to face in the vertical direction. As well as being formed,
a casing having an outer diameter larger than the outer diameter of the end of the vent tube;
a cylindrical upper portion having a valve protrusion capable of sealing the valve seat formed at the upper end; and a float having a large diameter portion projecting from the lower end of the casing and having a larger diameter than the inner diameter of the casing; It is fitted onto the outside of the casing or the float so as to be relatively movable in the vertical direction by a predetermined distance and relatively movable in a direction perpendicular to the vertical axis of the casing, and when moved in a direction perpendicular to the axis of the casing, the inner surface is an outer cylindrical body formed so as to be able to move the float upward by a slope effect by contacting the large diameter portion of the float, and having a weight that overcomes the buoyancy acting on the float, the inner surface of the casing and the above-mentioned A passage is formed in the sliding portion of the float with respect to the cylindrical upper part, and a through hole is formed in the outer cylindrical body, passing through the inside and outside thereof.

[Effect]

The float can move freely up and down relative to the casing,
Since the outer cylinder body is fitted into the casing and the float so that it can move relative to the casing and the float by a predetermined distance in the vertical direction, under normal conditions, the outer cylinder body is located at the lower end of its movable range due to its own weight, and its internal The float is also located at the lower end of its movable range due to its own weight. Therefore, at this time, the valve element at the upper end of the float is spaced downward from the valve seat of the casing. On the other hand, a passage is formed in the mutual sliding part between the cylindrical upper part of the float and the casing in which it is fitted, and a through hole is also formed in the outer cylinder, so that Fuel gas present in the valve seat can enter the interior of the barrel through the through holes in the barrel and then pass from the passageway between the float and the casing through the valve seat to the vent tube. On the other hand, when the fuel level rises due to a tilting of the fuel tank, this rising liquid level pushes up the float. The valve element at the upper end of the float then seals off the valve seat of the casing, preventing fuel from flowing into the vent tube. Furthermore, when the fuel tank rolls over, for example, by 90 degrees, the outer cylinder moves due to its own weight in a direction perpendicular to the axis of the casing, that is, downward in the rolled-over state. When this outer cylinder moves in a direction perpendicular to the axis of the casing, it can push the float upward, that is, toward the valve seat, due to the slope effect.
In this case as well, the valve element of the float seals the valve seat to prevent fuel from flowing into the vent tube. Furthermore, when the fuel tank overturns 180 degrees from its normal state, the outer cylinder body, which has the weight to overcome the buoyant force acting on the float, directly pushes down on the float that is about to rise, and pushes the valve protrusion onto the valve seat. Bring it into close contact. Therefore, in this case as well, fuel is prevented from flowing into the vent tube.

【effect】

Therefore, the fuel spill prevention device of the present invention can release the fuel gas in the tank to the vent tube when the fuel tank assumes a normal posture, but when the tank is tilted and the liquid level rises, or when the tank is rolled over. Or, in the event of a fall, it is possible to reliably prevent fuel from flowing into the vent tube. In this way, the fuel leakage prevention device of the present invention, which is installed at the tank and vent tube connection part, can reliably prevent fuel leakage, so the conventional gas-liquid separator and associated piping are completely unnecessary, and no parts are needed. Both the cost and the cost of installing the gas-liquid separator are reduced. Furthermore, compared to the fuel outflow prevention device disclosed in Japanese Utility Model Application Publication No. 58-106227 introduced previously, the following effects are achieved. First, in the conventional example shown in the above-mentioned publication, it was a steel ball loaded in the lower tapered part of the valve chamber that acted to shift the float to the valve sealing state in the event of rollover or overturning, but in the present invention, It is an outer cylinder enclosed in a casing and a float. It is clear that such an outer cylindrical body can be manufactured from a sheet metal at a lower cost than the above-mentioned steel ball, and therefore the cost of the entire apparatus of the present invention is dramatically reduced compared to the cost of the above-mentioned conventional example. Furthermore, in the above conventional example, the float and the steel balls are arranged in a vertically stacked manner, making the valve chamber bulky in the vertical direction, but in the present invention, the casing and the float are covered with an outer cylindrical body. It can be configured compactly in the vertical direction, and the overall weight can also be reduced. Furthermore, in the conventional example described above, the steel ball moves the float by rolling on the inner surface of the tapered portion in a direction inclined to the direction of gravity, but in the present invention, when the outer cylinder moves in the direction of gravity, Since the structure is such that the float is moved by the slope effect, the operational response of the float is dramatically superior to that of conventional models, and the reliability of the fuel spill prevention function is dramatically increased.

[Explanation of Examples]

Embodiments of the present invention will be specifically described below with reference to the drawings. The vent tube 1 has a flange 2 formed on the outer periphery of the base end of the vent tube 1 through a mounting hole 5 formed on the upper plate 4 of the fuel tank 3.
The fuel tank 3 is connected to the fuel tank 3 by fixing the fuel tank 3 to the fuel tank 3. The vent tube 1 extends slightly in the vertical direction within the tank, and a casing 6 is integrally connected to the end thereof. The casing 6 has a tapered pipe part 6a that expands downward, and a cylindrical pipe part 6b having a predetermined length that hangs down from the lower end of the tapered pipe part 6a. It is said to be larger than the outer diameter of 1. Further, the cone-shaped inner surface at the upper end of the tapered tube portion 6a functions as a valve seat 8 that performs a vent tube sealing function in cooperation with a float 7 to be described later. The lower part of the cylindrical tube part 6b is open, and a sub-valve seat 9 is formed on the lower end surface thereof. Note that the vent tube 1 and the casing 6 are made of metal and welded together, or
Alternatively, it can be integrally formed with resin. A float 7 is fitted into the casing 6 so as to be freely movable in the vertical direction. The float 7 has a cylindrical upper part 7a having a shape corresponding to the shape of the internal space of the casing 6, and a large diameter part 7b integrally continuous with the lower part of the cylindrical upper part 7a. That is, the cylindrical upper part 7a has a conical part corresponding to the tapered pipe part 6a of the casing on the upper part of the cylindrical part having an outer diameter corresponding to the cylindrical pipe part 6b of the casing. The tapered outer surface portion 7c at the upper end of this conical portion functions as a valve stem 10 that performs a valve tube sealing function in cooperation with the valve seat 8 of the casing. Further, the horizontal step portion 11 that separates the cylindrical upper portion 7a and the large diameter portion 7b is formed at a vertical position where it can come into close contact with the sub-valve seat 9 of the casing when the float 7 moves up the most. Therefore, when the float 7 is moving upward, the valve prong 10 at the tip comes into close contact with the valve seat 8, and at the same time, the horizontal step portion 11 comes into close contact with the auxiliary valve seat 9, so that the fuel in the tank is Outflow to the vent tube 1 is prevented in two stages. Also, this float 7
A tapered surface 13 whose diameter decreases downward is formed on the lower outer surface of the large diameter portion 7b. The float 7 is made of a material that can float in fuel. For example, urethane foam may be formed into a predetermined shape and subjected to gasoline-resistant surface treatment. Furthermore, a passage 12 is formed at the sliding portion between the inner surface of the casing 6 and the outer surface Z of the float 7, through which fuel gas can escape to the vent tube 1 when the float is moving downward. In this example, this passage is connected to float 7.
It is constructed by forming a vertical groove 17 on the outer periphery of the cylindrical upper part 7a. Note that this passage 12 can also be configured by forming a groove (not shown) on the inner surface of the casing 6. Furthermore, the outer cylinder 14 is fitted over the casing 6 and the float 7 so as to be movable relative to each other by a predetermined distance in the vertical direction and in a direction orthogonal to the vertical axis of the casing. The outer cylindrical body 14 has a cylindrical shape that encloses the casing 6 and the float 7 as a whole, and has a tapered upper part with a taper degree equivalent to that of the tapered pipe portion 6a of the casing 6. Inner surface 15
and the lower taber surface 1 of the float 7.
The lower half part 14b has a tapered inner surface 16 whose lower part is narrowed with a taper degree equivalent to 3. The vertical distance between the tapered inner surface 15 and the tapered inner surface 16 is set so that the float 7 can freely move up and down a certain distance. Also,
At the same time, a boundary 20 between the tapered inner surface 15 and the tapered inner surface 16
The outer diameter of the float 7 is made sufficiently larger than the maximum diameter of the casing 6 and the float 7. This means that the outer cylindrical body 14 is at its lowest moving position, where its upper tapered inner surface 15 abuts the outer surface of the tapered pipe portion 16a of the casing, and at the lowermost position where its lower tapered inner surface 16 abuts the upwardly moved tapered surface 13 of the float 7. This means that it can freely move up and down between the uppermost moving positions and also move in a direction perpendicular to the vertical axis of the casing 6, that is, in the lateral direction in FIG. In addition, when it moves in the lateral direction in this way, the float 7 is pushed upward due to the slope effect caused by mutual sliding between the lower tapered inner surface 16 and the tapered surface 13 of the float 7. The above-mentioned outer cylinder 14 is provided with a cylindrical part extending upwardly from the press-molded lower half part 14, as shown by imaginary lines in FIG.
is formed to form a plurality of triangular tongue pieces 19.19, this cylindrical part is placed over the casing 6 or the float 7 from below, and then the triangular tongue pieces 19.19 are bent inward at a predetermined angle to form and assemble the cylindrical portion. Can be attached. The slit 18 then functions as a through hole for introducing fuel gas into the outer cylinder body 14. The outer cylindrical body 14 has a specific weight that can overcome the buoyant force exerted on the float 7 in the fuel and sink the float. Next, the operation of this example will be explained. Under normal conditions, that is, when the tank is in its normal position,
When the fuel level is below the float, as shown in FIG. 1, the float 7 and the outer cylinder 14 assume the lowest position of their movable range due to their own weight. At this time, gaps are created between the sub-valve seat 9 of the casing 6 and the horizontal stepped portion 11 of the float, and between the valve protrusion 10 of the float 7 and the valve seat 8 of the casing, so that the fuel that has flowed into the inside of the outer cylinder body 14 The gas is
It is discharged into the vent tube 1 through the above-mentioned gaps and the passage 12 of the sliding portion of the casing 6 and the float 7. When the fuel level rises due to the tank being tilted, the liquid level pushes up the float 7, as shown in FIG.
seals the valve seat 8, and the horizontal stepped portion 11 seals the sub-valve seat 9, thereby preventing fuel from flowing into the vent tube 1 in two steps. Furthermore, when the tank is tilted 90 degrees, the outer cylinder 14 moves in a direction perpendicular to the axis of the casing, that is, in the direction of gravity, as shown in FIG. The float 7 is pushed in the valve sealing direction by the slope effect. Then, similarly to the above, the valve protrusion 10 and the horizontal step portion 11 of the float perform a sealing action, and fuel is prevented from flowing into the vent tube 1. Furthermore, if the tank falls over and ends up as shown in Figure 6, the outside f.
The tapered surface 16 of ll14 is the lower tapered surface 13 of the float.
is directly pushed down in the axial direction to move the float 7 in the valve sealing direction, thereby preventing fuel from flowing into the vent tube 1. In this way, when the float 7 is immersed in fuel, the outflow of fuel to the pentacle tube 1 is effectively prevented in any case. Of course, the scope of the invention is not limited to the embodiments described above. In the embodiment, in order to cause the float to move in the valve sealing direction due to the slope effect when the outer cylinder 14 moves in a direction perpendicular to the axis of the casing, the lower outer surface of the float and the lower inner surface of the outer cylinder are Although tapered surfaces as slopes are formed on both sides, the same effects as in the embodiment can be expected even if a tapered surface is formed on either one. Furthermore, the shapes of the valve seat and valve protrusions, or the shape of the casing can be modified in various designs.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a partially cutaway perspective view, FIG. 3 is a perspective view for explaining the method for manufacturing and assembling the outer cylinder, and FIG. 4 to 6 are action explanatory diagrams. 1...Bent tube, 6...Casing, 7...
・Float, 7a... (of the float) cylindrical upper part, 7b
... Large diameter lower part (of the float), 8... Valve seat, 10.
...Valve element, 12...Passage, 13...Tapered surface (slope), 14...Outer cylinder body, 16...Tapered surface (slope)
, 18...through hole.

Claims (1)

[Claims] (1) The end of the vent tube is fixed through the upper plate of the fuel tank. The end of the vent tube is connected to the end of the vent tube so as to face vertically, and a valve seat is formed on the inner surface of the upper end. a casing having a diameter larger than the outer diameter of the end of the vent tube; and a cylinder fitted into the casing so as to be freely movable in the vertical direction, and having a valve protrusion formed at its upper end capable of sealing the valve seat. a float having a large diameter portion projecting from the lower end of the casing and having a larger diameter than the inner diameter of the casing; The casing is fitted so as to be relatively movable in the direction perpendicular to the vertical axis, and when moved in the direction perpendicular to the axis of the casing, the inner surface comes into contact with the large diameter portion of the float, causing the float to move upward due to the slope effect. an outer cylindrical body formed as shown in FIG. With,
A fuel outflow prevention device characterized in that the outer cylindrical body is formed with a through hole passing through the inside and outside of the outer cylindrical body.