Fuel cutoff valve

A fuel cutoff valve is furnished with a casing defining a valve chamber, and a float mechanism housed to be able to rise and fall in the valve chamber. The casing is furnished with a closure plate situated in the space above the valve chamber and in a facing arrangement with a connecting passage. The closure plate is furnished with a vent hole that has been formed so as to divert the passage from the connecting passage to a second pipe line, and with a barrier wall that is situated in opposition to a first pipe line and that has been formed so as to divert the passage from the first pipe line to the second pipe line.

This application claims the benefit of and priority from Japanese Application No. 2008-142563 filed May 30, 2008, the content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fuel cutoff valve that is mounted on an upper wall of a fuel tank, and opens and closes a connecting passage to connect the fuel tank and outside, as well as to connect with another valve mechanism.

2. Description of the Related Art

A fuel tank is provided in its upper part with a fuel vapor processing system equipped with fuel cutoff valves, such as a full fuel control valve and a rollover valve, connected to a canister. Through opening and closing of the individual valves at prescribed fuel levels, venting of the fuel tank to the outside is assured while at the same time preventing liquid fuel from spilling to the outside. The rollover valve is designed to block fuel from flowing to the outside at a fuel level above full tank level in order to prevent fuel from spilling out when the vehicle tilts, during slalom driving of the vehicle, or similar situations.

In one known design, in addition to a pipe connecting it to the piping the leads to the canister, the full fuel control valve is provided with a pipe connecting it to the rollover valve, thereby allowing the piping that leads to the canister to be used in common and simplifying the piping arrangement (JP 2005-138677A). However, a problem with conventional full fuel control valves was that liquid fuel or fuel spray exiting the rollover valve tended to flow unimpeded towards the canister side.

SUMMARY

An advantage of some aspects of the invention is to provide a fuel cutoff valve that has a pipe adapted to ensure venting to another valve mechanism, and that makes it hard for liquid fuel or fuel spray inflowing from the pipe to flow to the outside.

According to an aspect of the invention is provided with a fuel cutoff valve that is mounted on an upper wall of a fuel tank, and opens and closes a connecting passage to connect the fuel tank and outside, as well as to connect with a valve mechanism. The fuel cutoff valve comprises a casing having (i) a valve chamber that connects the fuel tank and the connecting passage, (ii) a first pipe line that is connected to the valve mechanism and situated above the connecting passage, (iii) a second pipe line that is connected to the outside and situated above the connecting passage, (iv) a outside-communicating chamber that is situated in a space above the valve chamber and connect the connecting passage, the first pipe line and the second pipe line with each other, a float mechanism housed to be able to rise and fall in the valve chamber and adapted to open and close the connecting passage according to a fluid level in the fuel tank. The casing includes a closure plate that is disposed in the outside-communicating chamber and in a facing arrangement with the connecting passage, the closure plate being configured to include (i) a vent hole that is formed to divert a passage of the outside-communicating chamber, connecting between the connecting passage and the second pipe line, and (ii) a barrier wall that is situated in a facing arrangement with the first pipe line and that is formed to divert a passage of the outside-communicating chamber, connecting between the first pipe line and the second pipe line.

When fuel is supplied to a fuel tank employing the fuel cutoff valve in accordance with the first mode, fuel vapors in the upper part of the fuel tank will collide with the closure plate from the valve chamber and the connecting passage, becoming diverted thereby and escaping to the outside through the vent hole of the closure plate and the second pipe line. When the fuel in the fuel tank then reaches a prescribed level, the float mechanism will ascend through buoyancy owing to the inflow of fuel into the valve chamber. Due to the ascent of the float mechanism, the connecting passage will be closed off by the upper part of the float mechanism, thus blocking communication of the fuel tank with the outside and preventing fuel from flowing out from the fuel tank.

During turning or braking of the vehicle, if the fuel level in proximity to the fuel cutoff valve should rise causing liquid fuel or fuel spray to flow out from the connecting passage, the outflowing fuel will collide with the closure plate which has been situated in a facing arrangement with the connecting passage, and will be returned thereby. Moreover, because the vent hole of the closure plate has been formed at a location that does not face the connecting passage, i.e. because it has been formed so as to divert from the connecting passage to the second pipe line, liquid fuel or fuel spray will be prevented from flowing out from the second pipe line.

Additionally, the first pipe line which has been formed in the casing is connected to another valve mechanism, ensuring venting to the outside through the second pipe line. If liquid fuel or fuel spray from the other valve mechanism flows out from the first pipe line, the barrier wall formed on the closure plate will block inflow to the second pipe line and divert the passage that leads to the second pipe line. Therefore, liquid fuel etc. outflowing from the first pipe line will not head directly into the second pipe line.

In a second mode of the present invention, the vent hole is arranged facing the barrier wall and situated such that liquid fuel or fuel spray outflowing from the first pipe line will be directed towards the valve chamber. Through this arrangement, when fuel outflowing from the first pipe line collides with the barrier wall, it will be directed towards the valve chamber through the vent hole, so that the amount of outflowing fuel can be reduced.

In a third mode of the present invention, the barrier wall is disposed rising up from the closure plate so as to incline towards the vent hole. With this arrangement, the effect of directing the first pipe line towards the vent hole can be enhanced.

In a fourth mode of the present invention, the closure plate has a circular projecting portion projected upward in a facing arrangement with the connecting passage. With this arrangement, fuel outflowing from the connecting passage will collide with the circular projecting portion and be returned, preventing it from flowing to the outside.

In a fifth mode of the present invention, the closure plate has a sloping face that slopes towards the vent hole from the perimeter of the closure plate. With this arrangement, liquid fuel that has condensed in the outside-communicating chamber will not accumulate there, and will be rapidly returned to the fuel tank through the vent hole.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) General Configuration of Fuel Tank Venting Device

FIG. 1is an illustration depicting a fuel tank venting device equipped with a fuel cutoff valve in accordance with an embodiment of the present invention. The fuel tank venting device is furnished with a fuel cutoff valve10(full fuel control valve) and a rollover valve ROV (valve mechanism) of so-called ‘outside-tank’ design mounted on the upper wall inside a flattened fuel tank FT; a canister CN; and connector pipes connecting these. The fuel cutoff valve10is a valve designed to close when the fuel level inside the fuel tank FT has reached a first level FL1during fueling. The rollover valve ROV is a valve that is situated so as to ensure venting to the outside even if the vehicle should tilt, and that is designed to close when the fuel level has reached a second level FL2that is higher than the first level FL1. These valves serve to ensure venting of the fuel tank FT to the outside, as well as to prevent fuel from spilling out.

FIG. 2is a plan view of the fuel cutoff valve10; andFIG. 3is a sectional view taken along line3-3inFIG. 2. InFIG. 3, the fuel tank FT is made of composite resin material that includes polyethylene on its surface, and has a mounting hole FTb formed on the tank upper wall FTa. The fuel cutoff valve10is mounted to this tank upper wall FTa by thrusting its bottom part into the mounting hole FTb.

(2) Configuration of Fuel Shutoff Valve10Parts

The fuel cutoff valve10is composed mainly of a casing20, a float mechanism50, and a spring58. The casing20is furnished with a case body30, a closure plate35, a cover40, and a base plate45; the space bounded by the lower part of the case body30and the base plate45constitutes a valve chamber30S, and the float mechanism50, which is supported on the spring58, is housed in this valve chamber30S. An outside-communicating chamber40S is provided above the valve chamber30S, and the closure plate35is situated in this outside-communicating chamber40S.

FIG. 4is an exploded sectional view of the fuel cutoff valve10. The case body30is formed by a side wall31and a partition wall32that has been formed substantially at the center of the side wall31, with the space below the partition wall32constituting the valve chamber30S, and the space above, defined in cooperation with the cover40, constituting the outside-communicating chamber40S. A flange33projects in the diametrical direction from the upper part of the side wall31, and a joining portion34is formed in the upward direction from the outside peripheral part of the flange33. The upper face of the flange33is a section adapted to receive welding of the outside peripheral part of the closure plate35, while the joining portion34is a section adapted to be welded to the cover40. An engaging hole31ais formed in the lower part of the side wall31. The engaging hole31ais used for attaching the base plate45, as will be described later. A guide projection31bfor guiding the float mechanism50is formed in the vertical direction along the inside peripheral part of the side wall31.

A passage-defining projection32athat projects towards the bottom is formed in the center of the partition wall32; and a connecting passage32bthat connects to the valve chamber30S is formed passing through this passage-defining projection32a. The valve chamber30S side of the connecting passage32bconstitutes a seal portion32cof annular shape. An engaging hook45aadapted to engage the engaging hole31aof the case body30is formed in the base plate45side. Through engagement of the engaging hook45ain the engaging hole31a, the base plate45is attached so as to provide closure to the bottom opening of the case body30. A projecting portion45bof circular post shape is formed in the center part of the base plate45, and a spring supporting portion45cis formed in the outside peripheral part thereof. The spring supporting portion45cis adapted to receive the spring58and to support the spring58between it and the inside lower face of the float mechanism50. Communication holes45d(only one is illustrated) are formed at four locations encircling the projecting portion45b. The communication holes45dconnect the fuel tank FT interior with the valve chamber30S.

FIG. 5is a perspective view depicting the closure plate35. The closure plate35is furnished with a closure plate body35aof circular disk shape sloping towards the center part; its outside peripheral part constitutes a retaining edge35bintended for welding to the flange33, and its center part constitutes a circular projecting portion35c. The circular projecting portion35cserves as a grip during assembly of the fuel cutoff valve10, and also has the action of returning spray of fuel that has been sprayed out through the connecting passage32b. A vent hole35dis formed to the outside peripheral side of the circular projecting portion35c. The vent hole35dhas arcuate contours of prescribed width, that is, it extends along substantially half the circumference at a location exclusive of the retaining edge35band the circular projecting portion35c. A barrier wall35erises up from the closure plate body35aat a diametrical edge of the vent hole35b. The barrier wall35eis formed at an upward incline towards the vent hole35d, and as will be discussed later functions to direct liquid fuel and fuel spray towards the vent hole35d.

InFIG. 4, the cover40is furnished with a cover body41, a first pipe part42that projects out to the side from the center of the cover body41, a second pipe part43(seeFIG. 2) that is positioned at a right angle to the first pipe part42, and a flange44that is formed at the perimeter of the cover body41, these components being integrally formed. A first pipe line42ais defined to the inside of the first pipe part42; this first pipe line42aconnects at one end to the outside-communicating chamber40S, and at the other end connects to the rollover valve ROV (FIG. 1) through a pipe line. Inside the second pipe part43there is defined a second pipe line43aof larger passage area than the first pipe line42aand extending in the perpendicular direction (seeFIG. 2); the second pipe line43aconnects at one end to the outside-communicating chamber40S, and at the other end connects to the canister (FIG. 1) through a pipe line. Here, passage leading from the connecting passage32bto the second pipe line43awill be obstructed by the closure plate35as indicated by symbol P1inFIG. 5and diverted to the vent hole35d, and will circle around the circular projecting portion35cto connect with the second pipe line43athat connects to the canister. The passage leading from the first pipe line42ato the second pipe line43awill be obstructed and diverted by the barrier wall35eas indicated by symbol P2, and will circle around the circular projecting portion35cto connect with the second pipe line43a.

An outside welding portion44aadapted for welding to the tank upper wall FTa of the fuel tank FT is formed on the lower end of the flange44.

The float mechanism50is furnished with a float51, and a rubber seal member55that is installed on top of the float51. The float51is furnished with a float body52that has a buoyancy chamber51S open at the bottom and divided into multiple sections; and a valve supporting portion53that is projected up from the top center of the float body52. The valve supporting portion53is furnished with a supporting basal portion53aof circular post shape projecting from the center part of the float51, and a detent portion53bthat splays out from the top of the supporting basal portion53a.

The seal member55is furnished with a mounting part56having a mounting hole56a; and a seal part57of circular disk shape formed in the outside peripheral portion of the mounting part56. These components have been integrally molded of rubber. With this arrangement, the mounting hole56aof the mounting part56will be slipped around the supporting basal portion53aand detained there by the detent portion53bso that the seal member55is supported on the valve supporting portion53.

The float51will be supported by the spring58, which has been installed between the upper face of the buoyancy chamber51S of the float51and the spring supporting portion45cof the base plate45.

(3) Operation of Fuel Shutoff Valve10

Operation of the fuel cutoff valve10will now be described. As depicted inFIG. 3, when the fuel tank FT is supplied with fuel by fueling, fuel vapors in the upper part of the fuel tank FT will rise through the valve chamber30S and the connecting passage32bto collide with the closure plate35, then be diverted to escape towards the canister through the vent hole35d, the outside-communicating chamber40S, and the second pipe line43a. Then, when the fuel level in the fuel tank reaches a first level FL1, the fuel will now block off the communication holes45d, and thus tank internal pressure inside the fuel tank FT will rise. This rise in tank internal pressure will activate the auto-stop function of the fuel gun to stop fueling. In this state, a large pressure differential will arise between the tank internal pressure and the pressure inside the valve chamber30S, and the fuel level inside the valve chamber30S will rise. When the fuel level inside the valve chamber30S reaches a prescribed height, depending on the balance between the buoyancy of the float mechanism50and the upward force produced by the load of the spring58on the one hand, and the downward force produced by the weight of the float mechanism50, when the former overcomes that latter the float mechanism50will rise, and the seal part57of the seal member55will become seated in the seal portion32c, thereby closing off the connecting passage32b. Thus, during fueling of the fuel tank FT, fuel vapors will be allowed to escape from the fuel tank FT, while also preventing fuel from spilling to the outside of the fuel tank FT.

(4) Working Effects of the Embodiment

The embodiment described above affords the following working effects.

(4)-1 During fueling, when the fuel level in the fuel tank FT exceeds a first level FL1at which the communication holes45dare blocked off, tank internal pressure of the fuel tank FT will rise so that the auto-stop function can be activated.

(4)-2 If during turning or braking of the vehicle the fuel level in proximity to the fuel cutoff valve10should rise causing liquid fuel or fuel spray to flow out from the connecting passage32b, the outflowing fuel will collide with the closure plate35which has been situated in a facing arrangement with the connecting passage32b, and will be returned thereby. Moreover, because the vent hole35dof the closure plate35has been formed at a location that does not face the connecting passage32b, i.e. because it has been formed so as to divert from the connecting passage32bto the second pipe line43a, liquid fuel or fuel spray will be prevented from flowing out from the second pipe line43a.

(4)-3 As depicted inFIG. 6, the first pipe line42ais connected to the other rollover valve ROV (FIG. 1) so as to ensure venting to the canister through the outside-communicating chamber40S and the second pipe line43a. If liquid fuel or fuel spray from the rollover valve ROV flows out from the first pipe line42a, the barrier wall35eformed on the closure plate35will block inflow to the second pipe line43a, and divert the passage that leads to the second pipe line43a. Therefore, liquid fuel etc. that has outflowed from the first pipe line42awill not head directly into the second pipe line43a.

(4)-4 The barrier wall35eis positioned on an incline such that liquid fuel or fuel spray outflowing from the first pipe line42awill be directed through the vent hole35dand towards the valve chamber30S, so when fuel outflowing from the first pipe part42A collides with it, the fuel will be directing towards the vent hole35d, reducing the amount of outflowing fuel.

(4)-5 The circular projecting portion35cof the closure plate35is situated in a facing arrangement with the connecting passage32b, whereby fuel outflowing from the connecting passage32bwill be returned to the valve chamber30S and prevented from flowing to the outside.

(4)-6 As depicted inFIGS. 5 and 6, the closure plate body35aof the closure plate35has a sloping face that slopes towards the vent hole35dfrom the perimeter, whereby liquid fuel that has condensed in the outside-communicating chamber40S will not accumulate there, but will be rapidly returned to the fuel tank through the vent hole35d.

The present invention is not limited to the embodiment set forth hereinabove, and may be embodied in various modes without departing from the spirit thereof, as shown for example by the following modified embodiment.

The fuel cutoff valve10in accordance with the embodiment hereinabove has been designed so that when the fuel level has reached the bottom end of the fuel cutoff valve10, the float mechanism will rise due to fuel drawn into the valve chamber through the siphon effect, but no particular limitation is imposed thereby, and any design whereby the float will to rise and fall according to the liquid level in the valve chamber depending on the liquid level in the fuel tank would be acceptable.

The foregoing detailed description of the invention has been provided for the purpose of explaining the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. The foregoing detailed description is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Modifications and equivalents will be apparent to practitioners skilled in this art and are encompassed within the spirit and scope of the appended claims.