JP3186338B2 - Fuel shutoff valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cutoff valve for preventing liquid fuel from flowing out of a fuel tank to an activated carbon canister.

[0002]

2. Description of the Related Art Activated carbon canisters reduce the amount of fuel released from the fuel tank for vehicles into the atmosphere. When the internal pressure of the fuel tank increases, fuel vapor is discharged from the fuel tank to the atmosphere through the activated carbon canister, and most of the vapor is adsorbed by the activated carbon filled in the canister.

[0003] When a vehicle vibrates or leans violently,
The liquid fuel in the fuel tank may flow out to the activated carbon canister side. Therefore, in order to prevent the liquid fuel from flowing into the atmosphere in such a case, a fuel cutoff valve is provided at an outlet portion of the fuel tank in a communication pipe that connects the fuel tank and the activated carbon canister. The fuel cutoff valve has an internal pressure adjusting function of keeping the internal pressure of the fuel tank at a certain value or less, and has a liquid outflow preventing function of shutting off liquid fuel flowing from the fuel tank to the activated carbon canister side.

The conventional fuel cutoff valve has a float valve which operates and closes as the liquid level in the fuel tank rises in order to fulfill the function of preventing liquid outflow. In addition, a relief valve is provided separately from the float valve in order to perform the internal pressure adjusting function.

[0005]

In order to keep the internal pressure of the fuel tank low, the opening pressure of the relief valve is set low. However, when the valve opening pressure of the relief valve is low, when the liquid fuel vibrates violently due to the rocking of the vehicle, the liquid fuel opens the relief valve, and the liquid fuel may flow out to the activated carbon canister side. .

The present invention has been made to solve the above-mentioned problems in the prior art, and provides a fuel cutoff valve capable of preventing liquid fuel from flowing out of a relief valve even when the vehicle swings. The purpose is to:

[0007]

In order to solve the above-mentioned problems, a fuel cut-off valve according to the present invention is provided so as to penetrate a wall surface of a fuel tank and communicate with the inside of the fuel tank. A casing having a first vent hole communicating with the outside of the casing, and floating in response to the inflow of the liquid fuel into the casing housed in the casing, and closing the first vent hole when floating. A first seal portion having a first seal portion, the inside of which is divided into an upper chamber and a lower chamber;
, And a second float accommodated in the upper chamber, wherein the lower chamber has an opening at a lower end and an upper end is closed, and the upper chamber has the first float and the casing. The first seal portion has a second air hole communicating with the first air hole, and the second air hole includes the second air hole in the second air hole. The second chamber according to the pressure difference between the first vent and the upper chamber.
A relief valve for opening and closing the ventilation hole of the upper chamber, and the second float is configured to float when the second float floats from the communication port of the upper chamber in response to inflow of liquid fuel into the upper chamber. Has a second seal portion that closes the vent hole.

[0008]

When the liquid fuel flows into the casing, buoyancy is generated in the lower chamber and the first float rises, closing the first ventilation hole of the casing. At this time, the first vent is
In communication with the second vent, the second vent is closed by a relief valve. When the internal pressure of the fuel tank increases in this state, the relief valve opens according to the difference between the pressure of the first vent hole and the pressure of the upper chamber (that is, the internal pressure of the fuel tank). As a result, the fuel vapor in the fuel tank is discharged outside through the first and second ventilation holes. In a situation where the liquid fuel enters the upper chamber, the second float floats and closes the second vent, so that the fuel cutoff valve is closed as a whole regardless of the open / close state of the relief valve. .

[0009]

FIG. 1 is a sectional view showing a fuel cutoff valve 10 according to one embodiment of the present invention. This fuel cutoff valve 10
The case 20 includes a case 20, a float assembly 40 housed in the case 20, and a bottom plate 60 fitted in a lower portion of the case 20.

The case 20 has a substantially cylindrical shape, and a ventilation port 22 communicating with the activated carbon canister is formed at an upper end thereof. The ventilation port 22 is connected to the case 20 through a ventilation hole 24 formed at the center of the upper end surface of the case 20.
It communicates with the internal space. The lower end of the ventilation hole 24 is a conical valve seat 26. A flange portion 28 is formed on the outer peripheral surface near the upper end of the case 20.

A plurality of ventilation holes 30 through which fuel vapor mainly passes are formed on the side surface of the case near the lower portion of the flange portion 28, and a fuel passage through which liquid fuel mainly passes through near the lower end of the case 20. A hole 32 is formed.

The upper portion of the flange portion 28 is provided with a metal fixing plate 8.
0, and a packing 82 is fitted into a lower portion of the flange portion 28. A dustproof portion 84 is provided on the outer periphery of the lower portion of the fixed plate 80. In addition, the dustproof part 8
4 is formed integrally with the packing 82.

A stud bolt 92 is provided upright on an upper wall surface (shown by a broken line in the figure) of the fuel tank 90. The entire fuel cutoff valve 10 is fixed to the fuel tank by passing the stud bolt 92 through the through hole of the fixing plate 80 and tightening a nut into the stud bolt 92 from above the fixing plate 80. At this time, the packing 82 and the fuel tank 90
The fuel tank is sealed by the close contact of the wall surfaces. When the fixing plate 80 is fixed to the fuel tank 90 in this manner, the dustproof portion 84 around the fixing plate 80 is in close contact with the wall surface of the fuel tank 90, and dust is prevented from entering around the packing 82.

The bottom plate 60 to be fitted into the opening at the lower end of the case 20 is substantially cylindrical, and the side of the bottom plate 60
2 are formed. By fitting the engagement protrusion 62 into the engagement hole 34 provided on the side surface of the case 20,
The bottom plate 60 is fixed to the lower end of the case 20. A plurality of seating ribs 64 (convex portions) of the float assembly 40 are provided on the upper surface of the bottom plate 60. A concave spring seat 66 is formed inside the seating rib 64. Bottom plate 60
The fuel passage hole 68 through which the liquid fuel mainly passes
Is provided.

FIG. 2 is a sectional view showing only the float assembly 40. The float assembly 40 includes a lowermost first float 42, an upper float case 44 engaged on the first float 42, a second float 46 housed in the upper float case 44, It comprises a relief valve 48 fixed to the top of the float case 44 and a spring 50 installed in the second float 46.

FIG. 3A is a sectional view of the upper float case 44, and FIG.
FIG. 3C is a cross-sectional view of the second float 46 taken along the line CC. The upper float case 44 has a substantially cylindrical lower portion 100, an upper portion 102 having a substantially cylindrical shape and a small outer diameter, and a substantially conical seal projection 104 provided at a tip of the upper portion 102. I have.

A plurality of fins 106 and 108 are formed on the upper and lower portions of the outer peripheral surface of the lower portion 100, respectively.
The fins 106 and 108 have a function of reducing the contact area between the inner surface of the case 20 and the float assembly 40 to reduce frictional resistance. A ventilation hole 110 is provided on a side surface near the upper end of the lower portion 100. An engagement hole 112 and a communication port 114 are provided on a side surface near the lower end of the lower portion 100. A step 116 is formed on the inner surface of the upper end of the lower section 100. The relief valve 48 (FIG. 2) is ultrasonically welded to the step 116.

The interior of the upper portion 102 of the upper float case 44 constitutes a storage chamber for storing the relief valve 48. A ventilation hole 118 is formed at the center of the seal projection 104. The ventilation hole 118 is always in communication with the ventilation port 22 (FIG. 1) regardless of the open / close state of the fuel cutoff valve 10.

As shown in FIG. 3B, the second float 4
6 has a substantially conical seal projection 120 at the upper end,
Also, a plurality of fins 122 are formed on the outer peripheral surface along the vertical direction.
Are formed. As shown in FIG. 3C, the upper part of the second float 46 has a narrower internal space than the lower part, and the step between the upper part and the lower part is the spring seat 12.
Used as 4.

The first float 42 at the lowermost stage of the float assembly 40 is provided with a substantially cylindrical lower portion 130, an upper portion 132 having a substantially cylindrical and small outer diameter, and radially around the upper portion 132. Fin-shaped ribs 134
And an engagement protrusion 136 formed on the upper end of the lower portion 130. The spring 50 is interposed between the plurality of ribs 134 and the spring seat 124 of the second float 46. Further, the engagement protrusion 136 is fitted into the engagement hole 112 of the upper float case 44. A stepped spring seat 138 is formed inside the lower portion 130. Another spring 70 is interposed between the spring seat 138 and the spring seat 66 of the bottom plate 60 (FIG. 1).

The first float 42 and the second float 4
6 are both open at the lower end, and there is no opening at the side or upper end. As will be described later in detail, the second float 46 only floats itself, but the first float 42 has a function of floating the entire float assembly 40.

FIG. 4 is an exploded view of the relief valve 48.
The relief valve 48 includes a plate 140 and a spring 15
0, a ball 160, and a case 170. Convex part 142 formed on the outer periphery of the side surface of plate 140
Is fitted into a concave portion 172 formed on the inner peripheral surface of the case 170, whereby the entire relief valve 48 is assembled.

The plate 140 has a through hole 141 at the center, and the lower end thereof is a tubular portion 144 for guiding the spring 150. A plurality of slits 146 are formed in the tubular portion 144 in a vertical direction. These slits 146 allow the through holes 1 to be opened by the balls 160 when the balls 160 are raised and the relief valve 48 is opened.
This is to prevent 41 from being closed.

The lower side of the case 170 has a flange 1
74 are formed. The upper surface of the flange portion 174 is connected to the step portion 116 of the upper float case 44 (FIG.
(A) is ultrasonically welded. The outer diameter of the cylindrical portion 176 on the upper part of the case 170 is set to a value slightly smaller than the inner diameter of the upper portion 102 (FIG. 3A) of the upper float case 44. The center of the case 170 penetrates vertically, and the lower end thereof has a seal protrusion 120 of the second float 46.
A downward valve seat 178 corresponding to (FIG. 3B) is formed. An upward valve seat 180 for the ball 160 is formed above the valve seat 178. These valve seats 178, 180 are formed coaxially and communicate with each other. The ball 160 is urged downward by a spring 150 and is pressed against a valve seat 180 in a case 170. The spring load of the spring 150 is such that the ball 160 rises due to a predetermined pressure difference and the relief valve 48
Are set to open.

The case 20 described above and the first float 42
, An upper float case 44, a second float 46,
The bottom plate 60, the relief valve plate 140, and the relief valve case 170 are formed by injection molding a thermoplastic resin such as PA (polyamide) or POM (polyoxymethylene acetal resin). The three springs 50, 70, 150 and the ball 160 are made of stainless steel.

When assembling the fuel cutoff valve 10, a relief valve 48 is first assembled as shown in FIG. next,
This relief valve 48 is connected to the upper float case 44 (FIG. 3).
(A) is accommodated in the upper part 102 and fixed by ultrasonic welding. Thereafter, the second float 46, the spring 150, and the first float 42 are connected to the upper float case 4
4, and the engagement protrusion 136 of the first float 42 is fitted into the engagement hole 112 of the upper float case 44. Thus, the float assembly 40 shown in FIG. 2 is assembled. Next, the assembled float assembly 40 is
Then, the bottom plate 60 is fitted into the lower end of the case 20.
Finally, a packing 82 having a fixing plate 80 and a dust-proof portion 84 is attached to the outer periphery of the case 20 so that
Is completed.

FIG. 1 shows a normal state of the fuel cutoff valve 10. In a normal state, the liquid level of the fuel in the fuel tank exists below the fuel cutoff valve 10. At this time, the float assembly 40 has dropped to the lower end in the case 20 by its own weight, and the fuel cutoff valve 10 is in the open state. At this time, the relief valve 48 in the float assembly 40 is in the closed state. As shown by the arrow in FIG.
The fuel vapor FV inside the case 20 enters the inside of the case 20 through the vent hole 30 at the upper part of the case 20,
Through the vent port 22 side. Vent port 22
Is connected to an activated carbon canister (not shown), and most of the fuel vapor FV is adsorbed on the activated carbon.

FIG. 5 shows a state where the liquid level of the fuel in the fuel tank has risen. The liquid fuel LF enters the case 20 through the fuel passage holes 32 of the case 20 and the fuel passage holes 68 of the bottom plate 60. Case 20 and float assembly 4
Since the gap 0 communicates with the space in the fuel tank through the vent hole 30, the liquid level in the gap between the case 20 and the float assembly 40 is the same as the liquid level in the fuel tank. On the other hand, the liquid level inside the first float 42 of the float assembly 40 is lower than the liquid level in the fuel tank. This is because there is no opening at the upper end of the first float 42,
This is because the air inside cannot escape to the outside. When the liquid level difference H between the inside and outside of the float assembly 40 becomes a predetermined value or more, the float assembly 40 rises due to buoyancy, and the ventilation hole 24 at the upper end of the case 20 is closed. Thus, when the liquid level of the fuel in the fuel tank rises, the float assembly 40 rises and the fuel cutoff valve 10 closes. As a result, outflow of the liquid fuel from the fuel tank to the activated carbon canister side is prevented.

In addition to the case where the liquid level of the fuel tank rises relatively slowly as well as the case where the liquid level of the fuel tank fluctuates due to the rocking of the vehicle, the liquid outflow prevention function is provided in the same manner as described above. Be demonstrated.

FIG. 6 shows a case where the internal pressure of the fuel tank has risen from the state of FIG. When the relief valve is closed as shown in FIG. 5, the upper surface of the ball 160 of the relief valve 48 receives the pressure P0 on the activated carbon canister side (that is, the pressure of the ventilation port 22), and the lower surface of the ball 160 has the ventilation hole 110, An internal pressure P1 of the fuel tank is received through 30. When the internal pressure P1 of the fuel tank becomes higher than the pressure P0 on the activated carbon canister side by a predetermined value or more due to a rise in the temperature of the fuel tank or the like, the pressure difference causes the ball 160 to rise as shown in FIG. The pressure difference when the relief valve 48 is opened is set by adjusting the spring load of a spring 150 (FIG. 4) that urges the ball 160 downward.

When the relief valve 48 is opened, the fuel vapor FV in the fuel tank flows through the vent holes 30 and 110 and the relief valve 4.
8 and through the ventilation port 22 to the activated carbon canister side, and as a result, the internal pressure in the fuel tank decreases.

As described above, when the liquid level in the fuel tank rises, this fuel cutoff valve 10 causes the entire float assembly 40 to float and close, thereby exhibiting a liquid outflow prevention function (FIG. 5). When the internal pressure of the fuel tank rises in this state, the relief valve 48 opens to exhibit the function of preventing the internal pressure from rising (FIG. 6).

FIG. 7 is a cross-sectional view showing a state of the vehicle when swinging. When the liquid level of the fuel reaches near the upper end of the fuel cutoff valve 10 due to the vehicle swinging violently, the entire float assembly 40 rises due to the buoyancy of the first float 42. At this time,
Vent hole 110 and communication port 114 of upper float case 44
When the liquid fuel invades from above and the liquid level of the liquid fuel in the upper float case 44 becomes a predetermined height or more, the second float 46 floats and the valve seat 178 (FIG. 4) at the lower end of the relief valve 48 is moved. Will be closed. As can be seen from FIG. 7, in this state, the fuel cutoff valve 10 is closed regardless of whether the second float 46 is opened or closed.

As described above, when the fuel level fluctuates violently, the fuel shut-off valve 10 is closed as a whole regardless of the open / close state of the relief valve 48. Can be. Therefore, the relief valve 48
Even if the valve opening pressure is set relatively low, it is possible to prevent the liquid fuel from flowing out when the vehicle swings. In addition, even when the fuel level rises excessively due to a cause other than the swing of the vehicle, the second float 46 floats and closes the valve, so that the outflow of the liquid fuel can be prevented.

In the above embodiment, the relief valve 48 is accommodated in the upper portion 102 (FIG. 3A) of the upper float case 44 with almost no gap. However, the space in the upper section 102 may be made larger, and the relief valve 48 may be installed at the lower end thereof. Also,
Various modifications can be considered as the configuration of the components of each part of the float assembly 40.

FIG. 8 is a sectional view showing another embodiment of the present invention. This fuel cutoff valve 12 is provided with a float assembly 20.
Other than 0, it is the same as the fuel cutoff valve 10 shown in FIG. The first float 210 of the float aggregate 200 is shown in FIG.
In place of the upper portion 132 and the rib 134 of the first float 42 shown in FIG. 7, a plurality of radial fin-shaped ribs 212 are provided on the upper end surface. These ribs 212 are connected to the spring 5
It has the function of positioning 0 from the outside. The structures of the upper float case 220 and the relief valve of the float assembly 200 are different from those of the first embodiment.

FIG. 9 is an exploded view showing the structure of the upper float case 220 and the relief valve. The upper float case 220 in FIG. 9 has a function in which the seal protrusion 104 is omitted from the upper float case 44 shown in FIG. 3A and is combined with the relief valve case 170 shown in FIG.
9 has the function of combining the seal projection 104 of FIG. 3A and the relief valve plate 140 of FIG. The projection 224 is ultrasonically welded to the upper float case 220 on the lower surface of the flange 226.

The fuel cutoff valve 12 shown in FIG. 8 has the same effect as the fuel cutoff valve 10 shown in FIG. However, the fuel shut-off valve 12 in FIG. 8 has the relief valve case integrated with the upper float case 220 as understood from FIG.
There is an advantage that the number of parts is one less.

The present invention is not limited to the above-described embodiment, but can be implemented in various modes without departing from the gist of the invention.

[0040]

As described above, according to the fuel cutoff valve of the present invention, when the liquid level rises excessively, the second float closes, so that even when the vehicle swings, the second float closes. This has the effect that the outflow of liquid fuel can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a fuel cutoff valve as one embodiment of the present invention.

FIG. 2 is a sectional view showing only a float assembly.

FIG. 3 is an exploded view of the float assembly 40 excluding a relief valve.

FIG. 4 is an exploded view of the relief valve 48.

FIG. 5 is a sectional view showing a state in which the liquid level of the fuel in the fuel tank has risen.

FIG. 6 is a cross-sectional view showing a state in which the fuel tank internal pressure has increased.

FIG. 7 is a cross-sectional view showing a state in which a second float 46 floats due to fluctuations in the fuel level.

FIG. 8 is a sectional view showing another embodiment of the present invention.

FIG. 9 shows an upper float case 220 according to another embodiment.
Exploded view of the relief valve.

[Explanation of symbols]

 10, 12 ... fuel shutoff valve 20 ... case 22 ... ventilation port 24 ... ventilation hole 26 ... valve seat 28 ... flange portion 30 ... ventilation hole 32 ... fuel passage hole 34 ... engagement hole 40 ... float assembly 44 ... upper float case 48 relief valve 50 spring 60 bottom plate 62 engaging projection 64 seating rib 66 spring seat 68 fuel passage hole 70 spring 80 fixing plate 82 packing 84 dustproof section 90 fuel tank 92 stud Bolt 100 ... Lower step 102 ... Spring seat 102 ... Upper step 104 ... Seal projection 106 ... Fin 108 ... Fin 110 ... Vent hole 112 ... Engaging hole 114 ... Communication port 116 ... Stepped section 118 ... Vent hole 120 ... Seal projection 122 ... Fin 124 ... Spring seat 124 ... Vent hole 130 ... Lower step 132 ... Upper step 134 ... Rib 36 ... engagement projection 138 ... spring seat 140 ... relief valve plate 141 ... through-hole 142 ... convex part 144 ... tubular part 146 ... slit 150 ... spring 160 ... ball 170 ... relief valve case 172 ... concave part 174 ... flange part 176 ... cylinder Part 178 Valve seat 180 Valve seat 200 Float assembly 212 Rib 220 Upper float case 224 Projection 226 Flange FV Fuel vapor LF Liquid fuel

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60K 15/00-15/10 F16K 31/18 F16K 24/00

Claims (1)

(57) [Claims] 1. While adjusting the internal pressure of the fuel tank,
A fuel cutoff valve for preventing liquid fuel from flowing out of the fuel tank, wherein the fuel cutoff valve is disposed to penetrate a wall surface of the fuel tank, and has an opening communicating with the inside of the fuel tank; A first sealing portion which is accommodated in the casing and floats in response to the inflow of the liquid fuel into the casing, and closes the first vent when floating. And a first float having an interior partitioned into an upper chamber and a lower chamber; and a second float housed in the upper chamber, wherein the lower chamber has an opening at a lower end and an upper end is closed. The upper chamber has a communication port communicating with a gap between the first float and the casing, and the first seal portion has a second communication port communicating with the first ventilation hole. Having pores, In the second vent, a relief valve that opens and closes the second vent according to a pressure difference between the first vent and the upper chamber is provided, and the second float is provided. Has a second seal portion that closes the second vent when the liquid fuel floats in response to the inflow of the liquid fuel into the upper chamber from the communication port of the upper chamber. .