JP2002021667A - Liquid level detection valve for fuel tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detection valve for a fuel tank capable of surely carrying out a switching operation without causing malfunction by correctly detecting the liquid level of a fuel in the fuel tank. SOLUTION: This valve is so composed that a floating body 50 provided with, at its upper end part, a valve head 60 having an upper end surface spherically formed is housed in a nearly cylindrical body 3, and the valve is closed by raising the floating body 50 in conjunction with the rise of the liquid level to abut the upper end face of the valve head 60 on a valve seat 14 formed on the inside surface of the upper wall of the body 3. In this case, a hollow part is formed in the floating body 50 and an air vent window 53 communicating with the hollow part is formed therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mounted on an upper end wall of a fuel tank and always discharges vapor in the fuel tank to the outside of the fuel tank. A liquid level detection valve that closes the valve and intentionally raises the pressure in the fuel tank. More specifically, the liquid level detection valve detects the liquid level of the fuel in the fuel tank accurately.
The present invention relates to a liquid level detection valve for a fuel tank that can reliably perform opening and closing operations without causing a malfunction.

[0002]

2. Description of the Related Art Conventionally, vapor (fuel vapor) generated from fuel (gasoline) stored in a fuel tank of an automobile.
The fuel is used without waste by collecting it and supplying it to the engine as fuel. Recently, vapor generated at the time of refueling is also collected and used as fuel.

[0003] In this case, the fuel injection gun used for refueling is configured to automatically stop the lubrication when the tank is full due to a rise in the pressure in the tank. When the vapor to be discharged is recovered from the tank, the air in the tank is naturally discharged,
Even if the fuel level rises due to refueling, the tank internal pressure does not increase, and the fuel injection gun cannot detect a full tank.

Therefore, conventionally, a liquid level detecting valve is disposed at a connection portion between the vapor recovery pipe and the fuel tank, and detects the liquid level of the fuel injected almost to the full tank and closes the valve.
When the tank is full, the tank internal pressure is increased to stop the fuel injection gun. That is, as shown in FIG. 14, a liquid level detection valve b is provided on the inner surface of the upper wall of the fuel tank a, and when the fuel is injected, the vapor is collected into the canister c through the liquid level detection valve b. Reaches the liquid level detection valve b, the liquid level is detected, and the liquid level detection valve b
Is closed to increase the tank internal pressure.
In FIG. 14, d is a fuel injection pipe, and e is a switching valve provided at an intermediate portion of a vapor recovery pipe o connecting the liquid level detection valve b and the canister c. When an injection gun (not shown) is inserted, the changeover valve e is switched by the changeover switch f arranged in the injection pipe d, and the vapor collection is started through the liquid level detection valve b. Therefore, the vapor is collected through another vapor collection path g at all times except when refueling. Further, the vapor collected in the canister c is separated into fuel (gasoline) and air, supplies the fuel to the engine room, and releases the air to the atmosphere.

As a liquid level detecting valve b for detecting a full tank, a valve having a structure shown in FIG. 15 is conventionally known. That is, the liquid level detection valve accommodates a float body k having a dome-shaped valve head j formed in an upper part in a case i having an inverted funnel-shaped valve seat h at the upper end wall, and the case i described above. Is provided with a liquid inflow window m on the peripheral wall of.

In this liquid level detecting valve, as shown in FIG. 15 (A), the float body k is always located below, and a gap is provided between the valve head j and the valve seat h. It is formed to discharge vapor to the canister through this gap. Then, when the fuel level rises due to refueling, the fuel flows into the case i from the liquid inflow window m, and the float body k rises due to its buoyancy as shown by the dashed line in FIG. Then, the valve head j comes into close contact with the valve seat h, and the discharge of the vapor stops, thereby increasing the pressure in the tank.

[0007]

However, the above-mentioned conventional liquid level detecting valve is liable to malfunction, and the valve may be closed before the fuel is filled up or the fuel may be filled up. Even if the valve does not close completely.

That is, in the above-mentioned conventional liquid level detecting valve, the valve is constituted by a valve seat h whose inner peripheral surface is inclined in a reverse funnel shape and a hemispherical valve head j, as shown in FIG. In addition, when the float body k rises with the rise of the liquid level and approaches the valve seat h, the amount of decrease in the gap p between the valve head j and the inner peripheral surface of the valve seat h is the rising momentum q of the float body k. Instead, the gap p sharply decreases as the valve head j approaches the valve seat h. At this time, there is a vapor flow to be discharged in a gap p formed between the valve head j and the valve seat h, and a vapor recovery pipe o
Since the vapor flowing into the inside flows into the canister c (see FIG. 14), the inside of the valve seat h (the vapor collection pipe o)
Side), the valve head j is sucked to the valve seat h by the negative pressure, and the valve may be closed before the tank is full.

Further, as shown in FIG. 15, a predetermined clearance is provided between the outer peripheral surface of the float body k and the inner surface of the case i so that the float body k can freely move up and down. However, as shown in FIG. 15 (B), the clearance may cause the float body k to tilt due to the fluctuation of the fuel liquid level or the tilt of the tank a itself. In this case, the valve seat h and the valve A gap may be formed between the head j and the valve, and the valve may not be completely closed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and accurately detects a liquid level of fuel in a fuel tank and can reliably perform an opening and closing operation without causing a malfunction. It is an object to provide a detection valve.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is mounted on an upper end wall of a fuel tank and always discharges vapor in the fuel tank to the outside of the fuel tank. Is a liquid level detection valve that automatically closes the valve by detecting the rise of pressure and intentionally raises the pressure in the fuel tank, and has a valve body having a spherical upper end surface provided with a float body at the upper end. A valve seat is provided at the upper end of the inner surface of the main body, and the float body rises in the main body due to its buoyancy when the fuel level rises. Wherein the float body has a hollow portion opened at a lower end surface thereof and an air vent window communicating with the hollow portion. On the outer surface Providing the liquid level detection valve of the fuel tank, wherein the obtained those.

The liquid level detection valve of the present invention is attached to the upper end wall of the fuel tank as described above, and always discharges the vapor in the fuel tank to the outside of the fuel tank, and detects an increase in the fuel level when refueling. To automatically close the valve, intentionally increase the pressure in the fuel tank, and stop fuel injection from the fuel injection gun. According to the valve of the present invention, the float body The float body moves up and down stably and smoothly by the action of the air vent holes provided in the valve, preventing malfunction and opening and closing the valve reliably.

[0013] The float body constituting the liquid level detection valve of the present invention has a hollow portion opened at the lower end surface, and an air vent window communicating with the hollow portion is provided on the outer peripheral surface. This hollow portion can reduce the amount of material, and a spring that supports the upward movement of the float body is disposed in the hollow portion as in the embodiment described later, so that the vertical movement can be performed more smoothly. You can also

Here, in the present invention, the valve seat can be formed of a ring-shaped elastic body. For example, as shown in FIG. 12, the lower end opening is formed slightly smaller in diameter than the upper end opening. The valve seat h can be formed by a rubber ring body. Thereby, as shown in FIG. 12, the lower end opening surface of the valve seat h has a circular flat shape, and the rising amount s of the float body k and the decreasing amount t of the gap p between the valve seat h and the valve head j.
Becomes the same amount. Therefore, according to this valve, when the float body k rises and approaches the valve seat h, the gap p between the valve seat h and the valve head j does not suddenly decrease. It is possible to prevent the head j from being sucked by the valve seat h and closing the valve before the tank is full, and the air vent hole allows the float body to move up and down very stably. Thus, the opening and closing operation is performed more reliably.

Further, in the liquid level detecting valve of the present invention, it is preferable that the upper end surface of the spherical valve head is a spherical surface centered on the center point of the buoyancy of the float body. It is preferable that the upper end surface of the valve head j be a spherical surface having a radius r with the center point x of the buoyancy of the float body k as shown in FIG. Accordingly, as shown in FIG. 13, even if the float body k has a slope y, the slope y is based on the center point x of the buoyancy, and thus the spherical surface centered on the center point x. The relationship between the surface of the valve head j and the valve seat h does not change even if the inclination y occurs, and is always constant. Therefore, by making the upper end surface of the valve head j a spherical surface centered on the center point of the buoyancy of the float body k, even if the float body k is inclined y, the valve head is surely raised by the rise of the float body k. j is in close contact with the valve seat h, and the valve is reliably closed.

Here, in the liquid level detecting valve according to the present invention, the valve head is of a sheath shape having a pressure relief hole formed at the center of the spherical upper end surface. The valve head can be provided at the upper end of the float body by removably covering the upper part of the float body with the protruding closing projection, so that the valve head can be placed on the valve seat by negative pressure even if the liquid level drops. It is possible to reliably prevent the valve from being opened due to being sucked.

That is, in the liquid level detecting valve of the present invention having the valve head as described above, the pressure relief hole of the valve head is closed by the tip of the hole closing projection protruding from the upper end of the float body. In this state, the valve head is in close contact with the valve seat and the valve is closed. When the liquid level drops, the float body descends due to its own weight. At this time, even if the valve head is sucked to the valve seat by the negative pressure, the hole closing projection is integrated with the float body and the valve head falls. Is released, the suction by the negative pressure is released, the valve head descends by its own weight, and the valve is reliably opened. In this case, by providing an air vent hole also in the sheath-shaped valve head, the operation of the valve head is more reliably performed.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIGS. 1 to 3 show a liquid level detection valve according to an embodiment of the present invention. This liquid level detection valve is similar to the liquid level detection valve b shown in FIG. Attached to the upper end wall of the fuel tank a, the vapor in the fuel tank a is constantly discharged to the outside of the fuel tank a, and at the time of refueling, the fuel level is detected and the valve is automatically closed to detect the rise in the fuel level. Is purposely increased to stop fuel injection from the fuel injection gun.

As shown in FIGS. 1 to 3, the liquid level detecting valve includes a substantially cylindrical main body 3 composed of an upper main body 1 and a lower main body 2, and a float body accommodated in the main body 3. 4
And a valve head 5 attached to the upper end of the float body 4.

The upper body 1 constituting the body 3 is shown in FIG.
As shown in FIG. 7, a flange 7 is formed integrally with the outer peripheral edge of the lower end of the short-axis cylindrical base 6 having an upper end wall, and is directed to one side from the upper end wall of the base 6. A pipe body 8 is formed by projecting a pipe 8 bent in an L-shape, and a through hole 9 communicating with the inner space of the pipe 8 is formed in the upper end wall of the base 6.
The upper end of a cylindrical body 12 having an upper end wall in which a through hole 11 is formed is fitted and fixed in the base portion 6 described above.

The cylindrical body 12 constituting the upper body 1
A ring-shaped fitting flange 13 is provided on the inner peripheral
The cylindrical inner cap 13 integrally formed with the inner cap 13 is fitted and fixed so that the inner space thereof communicates with the through hole 11 in the upper end wall of the cylindrical body 12, and the outer periphery of the lower end of the inner cap 13 is fixed. A valve seat 14 made of a ring-shaped elastic body is attached so as to cover, and a pressing ring 15 is fitted and fixed around the valve seat 14. here,
The valve seat 14 is formed by forming an elastic body such as rubber into a ring shape, and has a lower end peripheral portion bent inward and a lower end opening formed to have a slightly smaller diameter than the upper end opening. The pressing ring 15 is fixed to the cylindrical body 12 by engaging a locking claw formed on the outer peripheral surface of the lower end thereof with a locking hole 16 provided at the upper end of the peripheral wall of the cylindrical body 12. The valve seat 1 is located between the presser ring 15 and the inner cap 13.
The valve seat 14 is fixed with the peripheral edge of the upper end of the valve seat 4 held therebetween. In this case, the valve seat 14 is attached to the lower end of the inner cap 13, inserted into the cylindrical body 12, and then the pressing ring 15 is pressed into the cylindrical body 12 to engage the locking claw of the pressing ring 15. The valve seat 14 can be fixed to the cylindrical body 12 by engaging with the locking hole 16 of the cylindrical body 12, and the mounting operation of the valve seat 14 can be performed very easily.

Further, on the peripheral surface of the upper end portion of the cylindrical body 12,
Four vapor distribution windows 17 are formed, and a connection protrusion 1 for connecting to the lower body 2 is provided at the lower end of the peripheral wall.
8, 18, 18 are formed, and
A positioning projection 19 is provided slightly above the projection.

On the other hand, as shown in FIG. 5, the lower body 2 has a cylindrical shape having a lower end wall, the upper end of the peripheral wall of which is formed to have a slightly larger diameter, and the upper end of the larger diameter portion. , Three connecting pieces 20, 20, 20 and three supporting pieces 21, 21, 21 slightly smaller than the connecting piece 20 are integrally formed. A connecting hole 22 for connecting to the upper main body 1 is formed in a central portion of each of the connecting pieces 20, and positioning recesses 23, 23, 23a are formed in an upper edge portion thereof. , One positioning recess 23a
Are formed smaller than the other positioning recesses 23,23. Further, on the inner surface of the peripheral wall, eight protrusions 28 formed in a semicircular cross section are provided at equal intervals so as to protrude along the axial direction of the lower main body 2.

The lower end wall of the lower body 2 has a central portion bulging inward in a circular trapezoidal shape, and the central portion of the trapezoidal portion 24 has a circular concave portion 24a. Is provided with a cushion body mounting hole 25. Furthermore,
On the lower end wall of the lower main body 2, eight liquid inflow holes 26 are circularly arranged at regular intervals so as to surround the trapezoidal portion 24.

The main body 3 constituting the liquid level detection valve of the present embodiment is
As shown in FIGS. 1 to 3, the lower end of the upper body 1 is inserted into the upper end of the lower body 2, and each connection protrusion 18 of the upper body 1 is formed on each connection piece 20 of the lower body 2. The upper main body 1 and the lower main body 2 are connected and fixed by engaging with each of the connection holes 22 thus formed. in this case,
As shown in FIGS. 1 to 3, a rubber cushion 27 is fitted into the cushion mounting hole 25 of the lower main body 2 from the inside of the lower main body 2. When the upper main body 1 and the lower main body 2 are connected and fixed, the positioning projections 19 of the upper main body 1 are fitted and positioned in the respective positioning recesses 23 of the lower main body 2 so as to prevent rattling. It has become.

Next, as shown in FIG. 6, the float body 4 accommodated in the main body 3 partitions the inner surface of the cylindrical base 29 in the axially intermediate portion with a partition wall 30.
A cylindrical valve head support column 31 having an upper end wall protrudes from the center of the upper surface of the partition wall 30 and a cylindrical buoyant body 32 is suspended from the center of the lower surface of the partition wall 30. In this case, the partition wall 3
A through-hole is provided at the center of 0 so that the inner space of the valve head support column 31 communicates with the inner space of the buoyant body 32. A hole closing projection 33 is provided on the upper surface of the valve head support column 31, and eight ridges 34 having a semicircular cross section are provided at equal intervals on the outer peripheral surface of the valve head support column 31. And is formed along the axial direction. Further, the base 29
In the middle part of the peripheral wall in the height direction, two air vent windows 35 are provided below the partition wall 30, and the partition wall 30 is provided outside the buoyant body 32. Six through holes 36 for draining liquid are formed in a circular array at equal intervals.

As shown in FIGS. 1 to 3, the float body 4 is housed in the main body 3 so as to be vertically movable, and the partition wall 30 of the float body 4 and the lower body 2
A spring 37 is arranged between the lower end wall of the float body 4 and the buoyant body 32 of the float body 4, and the spring 37 moves upward even with a slight buoyancy due to the urging force of the spring 37. The float body 4 is always located at the lower limit of movement inside the main body 3 against the urging force of the spring 37 by its own weight. Further, the float body 4 is in a state where the ridges 28 (see FIG. 5) protruding from the inner peripheral surface of the lower main body 2 are in line contact with the outer peripheral surface of the base body 29, so that the float body 4 is stably and vertically moved It can move.

As shown in FIG. 7, the valve head 5 attached to the float body 4 has a pressure at the center of the upper end wall of a sheath-shaped valve head body 38 having a dome-shaped upper end wall. A punching hole 39 is formed, and a small cylindrical projection 40 communicating with the pressurizing hole 39 is formed on the inner surface of the upper end wall. The peripheral wall of the valve head body 38 is formed to be thick from the axial middle portion to the lower end, and a step portion 41 is formed on the axial middle portion peripheral surface of the valve head body 38 and the step portion 41 is formed. A cylindrical peripheral wall 42 is formed integrally with the outer peripheral surface of the upper part of the valve head body 38 at a predetermined distance from the outer peripheral edge upward. In this case, the peripheral wall body 42
Is formed lower than the valve head body 38, and the valve head body 3
8 is in a state of protruding upward from the upper edge of the peripheral wall body 42. The thickening lower peripheral wall of the valve head body 38 is formed with six lightening recesses 43, and the step portion 41 is formed with the lightening recesses 4.
Six liquid draining holes (air venting holes) 44 communicating with 3 are circularly arranged along the circumferential direction.

As shown in FIGS. 1 to 3, the valve head 5 is attached to the upper end of the float body 4 by detachably covering the valve head support column 31 of the float body 4. . At this time, as shown in FIG. 1, the lower end opening of the small cylindrical projection 40 communicating with the pressure relief hole 39 of the valve head 5 is a hole closing projection formed on the upper surface of the valve head support column 31. 33 is closed by the tip. The valve head 5 is supported in a state where its inner peripheral surface is in line contact with the ridge 34 (see FIG. 6) protruding from the outer peripheral surface of the valve head support column 31 and is stable without wobbling. It can move up and down in the posture.

Next, the operation of the liquid level detecting valve of the present embodiment will be described. This liquid level detection valve is attached to the upper end wall of the fuel tank as described above, and always discharges the vapor in the fuel tank to the outside of the fuel tank. This is for closing the valve and intentionally increasing the pressure in the fuel tank to stop fuel injection from the fuel injection gun.

That is, normally, as shown in FIG.
The float body 4 is located at the lower limit of movement in the main body 3, and at this time, the upper surface of the valve head body 38 of the valve head 5 attached to the upper end of the float body 4 and the inner surface of the upper wall of the main body 3 A gap is formed between the valve seat 14 and the fuel tank, and the vapor in the fuel tank is discharged to the outside of the tank through the gap.

At the time of refueling, when the liquid level of the fuel in the fuel tank rises and reaches the liquid level detecting valve of the present embodiment, the fuel is supplied from the liquid inlet hole 26 formed in the lower end wall of the lower main body 2 to the main body 3.
As shown in FIG. 2, the float body 4 rises due to its buoyancy, and the float body 4
The upper end surface of the valve head body 38 of the valve head 5 attached to the upper end portion is in close contact with the valve seat 14, and closes the lower end opening of the valve seat 14. At this time, the upward movement of the float body 4 is stably and smoothly performed by the action of the air vent window 35 provided in the float body 4.

As a result, the liquid level detection valve is closed, and the air inside the vapor including the vapor is not discharged out of the fuel tank, the tank internal pressure rises, and the fuel injection gun stops fuel injection.

Here, in the liquid level detecting valve of the present embodiment, the valve seat 14 is formed of a ring-shaped elastic body.
Has a circular planar shape at its lower end opening surface. For this reason, when the float body 4 rises with the fuel level rise, the amount of rise of the float body 4 and the decrease amount of the gap between the valve seat 14 and the valve head main body 38 become the same. Therefore, according to this liquid level detection valve, when the float body 4 rises and the upper end surface of the valve head body 38 approaches the valve seat 14, the gap between the valve seat 4 and the upper end surface of the valve head body 38 is sharply increased. Thus, it is possible to prevent as much as possible that the valve head 5 is sucked to the valve seat 14 by the negative pressure and the valve is closed before the tank is full.

Next, when the fuel level in the fuel tank drops due to the consumption of the fuel, the fuel in the main body 3 is drained out of the main body 3 through the liquid inflow hole 26 and the float body 4 Is lowered by its own weight, and the upper end surface of the valve head body 38 of the valve head 5 attached to the upper end of the float body 4 and the valve seat 1
4, a gap is formed, and the gap returns to the initial state shown in FIG. Also at this time, the lowering movement of the float body 4 is stably and smoothly performed by the action of the air vent window 35.

In this case, in the liquid level detecting valve of the present embodiment, a sheath-shaped valve head 5 having a pressure release hole 39 formed in the center of the upper end is used, and the valve head 5 is provided above the float body 4. Since the valve head is provided at the upper end of the float body 4 by being freely inserted into and removed from the valve head support column 31 having the hole closing projection 33, the valve head 5 can be closed by the negative pressure even after the liquid level drops. The sticking to the seat 8 can be reliably prevented.

That is, as shown in FIG. 2, the liquid level detection valve of the present embodiment having the valve head 5 as described above
In a state where the pressure relief hole 39 of the valve head 5 is closed by the tip of the hole closing protrusion 33 protruding from the upper end surface of the valve head support column 31 of the float body 4, the valve head 5 is mounted on the valve head body 38. The end face is in close contact with the valve seat 14 and the valve is closed. And
When the liquid level drops and the fuel in the main body 3 is discharged, the float body 4 descends by its own weight. Even if the valve head 5 is sucked to the valve seat 14 by the negative pressure at this time, it is shown in FIG. As described above, the valve head support column 31 descends integrally with the float body 4 to open the pressure release hole 39 of the valve head 5, the suction by the negative pressure is released, and the valve head 5 descends by its own weight. 1 ensures that the valve opens. The liquid level detection valve of the present embodiment is configured so that the valve is opened by the two-step operation as described above. Therefore, even if the gas discharge port of the valve seat 14 is formed large, the valve head 5 is not affected by the negative pressure. This prevents the valve from opening due to being sucked, so that the gas outlet of the valve seat 14 is formed relatively large, so that the vapor in the fuel tank can be discharged well. In this case, the downward movement of the valve head 5 is performed smoothly and favorably by the action of the liquid drain hole (air release hole) 44 provided in the valve head 5.

Further, in the liquid level detecting valve of the present embodiment, a hollow portion is provided between the outer peripheral wall (cylindrical base 29) of the float body 4 and the buoyant body 32, so that the material can be reduced. In addition, the lifting motion of the float body 4 is supported by a spring disposed in the hollow portion, and the float body 4 smoothly rises even with a slight buoyancy by the urging force of the spring 37. Thus, the valve can be closed reliably and promptly.

Further, in the liquid level detecting valve of the present embodiment, the valve seat 14 is formed of an elastic material such as rubber as described above.
Further, since the rubber cushion body 27 is attached to the inner surface of the bottom wall of the main body 1, even if the float body 4 and the valve head 5 move up and down due to vibration or the like, the impact is absorbed by the valve seat 14 and the cushion body 27. Thus, it is possible to reliably prevent the float body 4 and the valve head 5 from colliding with the inner surface of the main body 3 and generating noise.

[Second Embodiment] FIGS. 8 to 10 show a liquid level detecting valve of a fuel tank according to another embodiment of the present invention. The liquid level detecting valve includes a float body 50 and a valve head 60. 11 is the same as the liquid level detection valve of the first embodiment except that the one shown in FIG. 11 is used.

As shown in FIG. 11 (B), the float body 50 constituting the liquid level detection valve has a substantially cylindrical block-shaped float body 51 having a lower portion formed in a slightly smaller diameter cylindrical shape. At the lower part, a cylindrical outer cylinder 52
The float body 50 of the float body 50 is formed integrally with the lower peripheral surface in a state of being separated by a predetermined distance.
An air chamber 53 is formed in the upper end portion, and a hole closing projection 54 projects from the center of the upper surface of the float main body 51.

As shown in FIG. 11, the valve head 60 has a cylindrical shape having a dome-shaped upper end wall. Is formed, and a cylindrical projection 40 communicating with the pressure release hole 39 is integrally provided at the center on the inner surface side of the upper end wall. As shown in FIG. 11, the valve head 60 is used so as to be able to be freely inserted and removed from the float body 50. In this manner, the buoyancy of the valve body 60 when the valve head 60 is covered on the float body 50 is used. The center point of
The upper end wall of the valve head 60 is a spherical surface having a radius r centered on the center point x of the buoyancy at a point indicated by reference numeral x in FIG. Note that reference numerals 61 and 62 in FIG.
Is a liquid drainage window (air vent hole) formed in the peripheral wall of the valve head 60.

As shown in FIGS. 8 to 10, the float body 50 and the valve head 60 are housed in a main body 3 composed of an upper main body 1 and a lower main body 2 so as to be vertically movable. In this case, a spring 37 is provided between the lower part of the float body 51 of the float body 50 and the outer cylindrical body 52, and the float body 50 is urged upward. Since other configurations are the same as those of the liquid level detecting valve of the first embodiment, the same components are denoted by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 8, the liquid level detecting valve is always located at the lower limit of the float body 50 in the main body 3 at this time.
A gap is formed between the upper end surface of the valve head 60 attached to the valve body and the valve seat 14 attached to the inner surface of the upper wall of the main body 3, and the vapor in the fuel tank is discharged to the outside of the tank through this gap. It has become.

At the time of refueling, when the liquid level of the fuel in the fuel tank rises and reaches the liquid level detection valve of the present embodiment, the fuel is supplied from the liquid inlet hole 26 formed in the lower end wall of the lower main body 2 to the main body 3.
As shown in FIG. 9, the float body 50 rises due to its buoyancy, and the upper end surface of the valve head 60 attached to the float body 50 comes into contact with the valve seat 14. The valve seat 14 closes and closes the lower end opening of the valve seat 14.

As a result, the liquid level detection valve is closed, and the air inside the vapor, including the vapor, is not discharged out of the fuel tank, and the tank internal pressure rises to stop fuel injection from the fuel injection gun.

Here, in the liquid level detecting valve of the present embodiment, the upper end surface of the valve head 60 formed in a spherical shape is a spherical surface centered on the center point x of the buoyancy of the float body 50. As a result, even if the float body 50 is tilted, the tilt is centered on the center point x of the buoyancy. Therefore, the upper end surface of the valve head 60 which is a spherical surface centered on the center point x and the valve seat 14
Does not change even if the inclination occurs, and is always constant. Therefore, according to this valve, even if the float body 50 is inclined, the upper end surface of the valve head 60 is securely brought into close contact with the valve seat h by the rise of the float body 50, and the valve is securely closed.

Next, when the fuel level of the fuel in the fuel tank drops due to consumption of the fuel, the fuel in the main body 3 is drained out of the main body 3 through the liquid inlet hole 26 with the lowering of the liquid level, and the float 50 Is lowered by its own weight, a gap is formed between the upper end surface of the valve head 60 attached to the float body 50 and the valve seat 14, and returns to the initial state shown in FIG. .

In this case, the liquid level detecting valve of this embodiment is
As shown in FIG. 9, in a state where the pressure relief hole 39 of the valve head 60 is closed by the tip of the hole closing protrusion 54 protruding from the upper end surface of the float body 50, the upper end surface of the valve head 60 is closed. Are in close contact with the valve seat 14 and the valve is closed. And
When the liquid level falls and the fuel in the main body 3 is discharged, the float body 50 descends by its own weight. Even if the valve head 60 is sucked to the valve seat 14 by the negative pressure at this time, as shown in FIG. As shown in FIG. 8, the hole closing projection 54 descends integrally with the float body 50 to open the pressure release hole 39 of the valve head 60, the suction by the negative pressure is released, and the valve head 60 descends by its own weight. As shown in the figure, the valve is surely opened.

The functions and effects of the liquid level detecting valve of the present embodiment other than those described above are the same as those of the liquid level detecting valve of the above-described first embodiment, and a description thereof will be omitted.

Although the embodiment of the present invention has been described above, the liquid level detecting valve of the fuel tank of the present invention is not limited to the above-described embodiment. It can also be formed integrally. Further, other configurations such as the shapes of the main body 3, the float bodies 4, 50, the valve heads 5, 60, and the like may be appropriately changed without departing from the gist of the present invention.

[0052]

As described above, according to the fuel tank level detecting valve of the present invention, the fuel level in the fuel tank can be accurately detected, and the opening and closing operation can be performed without malfunction. Is what you can do.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a liquid level detection valve according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a closed state of the liquid level detection valve.

FIG. 3 is a cross-sectional view showing an intermediate operation when the liquid level detection valve shifts from a closed state to an open state.

4A and 4B show an upper body constituting the liquid level detection valve, wherein FIG. 4A is a front view, FIG. 4B is a sectional view, and FIG. 4C is a bottom view.

5 (A) is a plan view, FIG. 5 (B) is a front view, FIG. 5 (C) is a cross-sectional view, and FIG. 5 (D) is a bottom view.

6 (A) is a plan view, FIG. 6 (B) is a front view, FIG. 6 (C) is a sectional view, and FIG. 6 (D) is a bottom view, showing a float body constituting the liquid level detection valve.

7 (A) is a plan view, FIG. 7 (B) is a front view, FIG. 7 (C) is a cross-sectional view, and FIG. 7 (D) is a bottom view.

FIG. 8 is a cross-sectional view illustrating a liquid level detection valve according to another embodiment of the present invention.

FIG. 9 is a sectional view showing a closed state of the liquid level detection valve.

FIG. 10 is a cross-sectional view showing an intermediate operation when the liquid level detection valve shifts from a closed state to an open state.

11A and 11B show a float body and a valve head constituting the liquid level detection valve, wherein FIG. 11A is a front view and FIG. 11B is a sectional view.

FIG. 12 is an explanatory diagram illustrating the operation and effect of the present invention.

FIG. 13 is an explanatory diagram illustrating another operation and effect of the present invention.

FIG. 14 is a schematic view showing a vapor recovery mechanism of a vehicle fuel tank.

FIG. 15 is a sectional view showing a conventional liquid level detection valve.

FIG. 16 is an explanatory diagram for explaining a problem of a conventional liquid level detection valve.

[Explanation of symbols]

 3 Body 4,50 Float body 5,60 Valve head 14 Valve seat 35 Air vent window 39 Depressurizing hole 33,54 Hole closing projection x Center point of buoyancy

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16K 31/18 F16K 31/20 31/20 B60K 15/02 F

Claims (5)

[Claims] 1. A fuel tank is attached to an upper end wall of a fuel tank, and always discharges vapor in the fuel tank to the outside of the fuel tank, and at the time of refueling, detects a rise in fuel level and automatically closes a valve. A liquid level detection valve that intentionally raises the internal pressure, and a valve head having a spherical upper end surface accommodates a float body provided at the upper end portion in a substantially cylindrical main body so as to be vertically movable, A valve seat is provided at the upper end of the inner surface of the main body, and the float body rises inside the main body due to its buoyancy due to a rise in the fuel level, and the valve head is brought into close contact with the valve seat to close the valve. In the liquid level detection valve configured as described above, the float body has a hollow portion opened at the lower end surface, and an air vent window communicating with the hollow portion is provided on the outer peripheral surface. Fuel tank level Detection valve. 2. A spring is disposed in a hollow portion provided in the float body, and the float body is located at a lower limit of movement within the main body by its own weight against the urging force of the spring, and has a lower fuel level. 2. The liquid level detection valve according to claim 1, wherein the float body is easily raised by the urging force of the spring when ascending. 3. A valve head having a sheath shape in which a depressurizing hole is formed in the center of an upper end surface formed in a spherical shape, and the valve head is formed on an upper portion of a float body in which a hole closing projection is provided. 3. The liquid level detection valve for a fuel tank according to claim 1, wherein a valve head is provided at an upper end portion of the float body by being detachably put on the float body. 4. The liquid level detecting valve for a fuel tank according to claim 3, wherein an air vent hole is also formed in a sheath-shaped valve head covered on the upper part of the float body. 5. The liquid level detection valve for a fuel tank according to claim 1, wherein the valve seat is formed of a ring-shaped elastic body.