Abstract:
A valve for preventing fuel leaking from a fuel tank includes a housing that has a passage that communicates with the outside. In the housing there is a float that is used to open and close the passage by being moved axially along the housing. The valve is provided with a device to guide the float to close the passage. The device includes a gap formed between the housing and the float that increases in size with increasing distance from the passage.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a valve for a vehicle fuel tank, more particularly to an anti-spill valve for installation in the top of the fuel tank of a vehicle, particularly an automobile, for preventing pressure buildup in the tank during normal operation by allowing internal tank pressure to escape to the exterior and for preventing spillage of gasoline to the exterior when the vehicle suddenly accelerates, turns sharply or overturns. 
     2. Description of the Prior Art 
     FIG. 20 is a cross-sectional diagram of a prior art valve, and FIG. 21 shows the valve of FIG. 20 turned sideways. In FIGS. 20 and 21, reference numeral  1  denotes a housing formed of synthetic resin, comprising a housing unit  2  and a detachable cap  7 . The housing unit  2  has a passage  3   a  that communicates with the outside, provided in the center of the housing unit  2 . Going toward the interior of the housing unit  2 , the passage  3   a  expands into a conical valve seat  3   b  formed in a round ceiling  3 . From the outer edge of the ceiling  3 , a cylindrical side wall  4  extends downward. The side wall  4  is provided with a plurality of holes  4   a , a plurality of claws  4   b  around the lower circumference that are thicker toward the upper end, and guide ribs  4   c  used to guide a float  11  (described below). The guide ribs  4   c  are of equal height and are disposed axially at set intervals around the inside of the side wall  4 . From the center of the ceiling  3 , a connecting pipe  5  having a central passage  5   a  that communicates with the passage  3   a  extends radially out past the side wall  4 . An annular mounting member  6  provided on the outside of the side wall  4  is used to mount the housing unit  2  on a fuel tank. 
     The cap  7  comprises a cylindrical side wall  8  with radial engaging holes  8   a  that correspond to the claws  4   b  on the side wall  4  and float guide ribs  8   b  disposed axially at set intervals around the inside surface, and a bottom  9  that closes the lower end of the side wall  8 . The bottom  9  has a plurality of vertical holes  9   a  that enable the bottom  9  to function as a filter. Reference numeral  11  denotes a float housed in the housing  1 . The float  11  is cylindrical in shape and formed of synthetic resin. The lower end of the float  11  has an annular concave portion  12 , and is provided with a plurality of vertical through holes  13  that communicate with the concave portion  12 , and a valve head  14  that projects up from the top of the float and operates to open and close the passage  3   a  by separation from and contact with the valve seat  3   b . A coil spring  21  is disposed between the housing bottom  9  and the float  11  to help urge the float  11  upwardly. 
     Operation of the valve will now be described. The valve is normally mounted on a fuel tank (not shown) with the housing  1  oriented vertically, as shown in FIG.  20 . In this state, the float  11  descends under its own weight against the force of the coil spring  21 , separating the valve head  14  from the valve seat  3   b  and opening the passage  3   a . Gasoline vapor formed in the fuel tank is therefore able to flow out via the holes  4   a  and  9   a , the space between the side wall  4  and the float  11 , and the passages  3   a  and  5   a , preventing the pressure inside the fuel tank becoming elevated. 
     Although a buoyant force acts on the float  11  when gasoline enters the housing  1  through the holes  9   a  owing to a large inertial force produced by rapid acceleration or sharp turning of the vehicle, this force alone is not strong enough to raise the float  11  since the specific gravity of the float  11  is greater than that of the gasoline. However, the buoyant force combined with the weak force of the spring  21  acting upwardly on the float is sufficient to raise the float and bring the valve head  14  into close contact with the valve seat  3   b , closing the passage  3   a  and thereby preventing gasoline from flowing out of the fuel tank. When the vehicle returns to a normal state and gasoline in the housing  1  flows back through the holes  9   a  into the fuel tank, under its own weight the float  11  descends, compressing the spring  21 , whereby the valve head  14  separates from the valve seat  3   b , opening the passage  3   a . If the vehicle should turn over onto its side, the valve will also be turned sideways, as shown in FIG. 21, and the force of the coil spring  21  will move the float  11  in the direction of the passage  3   a  until the passage  3   a  is closed by the abutment of the valve head  14  against the valve seat  3   b , thus preventing gasoline in the fuel tank spilling to the outside. 
     In the prior art valve, a clearance h is provided between the guide ribs  4   c  and the float  11  to allow the float  11  to move smoothly. Therefore, if the vehicle falls on its side, as shown in FIG. 21, the center axis of the valve head  14  (the axis of the float  11 ) is subjected to a parallel displacement down from the axis of the passage  3   a  by the amount of the clearance h. In this state, even if the float  11  is moved with the intention of closing the passage  3   a  with the valve head  14 , the valve head  14  will contact the lower sloping face of the conical valve seat  3   b.    
     In order to have the valve head  14  close the passage  3   a , a force is required that lifts the valve head  14 . This force is provided by the coil spring  21 , but the lifting force is reduced by the high frictional resistance that exists between the sloping portion of the valve seat  3   b  and the valve head  14 . Since this can prevent the passage  3   a  being promptly and fully closed by the valve head  14 , gasoline can leak from the fuel tank. 
     This invention was accomplished in response to the foregoing circumstances and has as an object to provide a valve that, even when turned sideways, can suppress leakage of fuel to the exterior by promptly closing a passage that communicates with the outside. 
     SUMMARY OF THE INVENTION 
     For achieving the aforesaid object, the invention provides a valve comprising a housing having an outside-communicating passage and a float provided in the housing that opens and closes the passage by moving axially along the housing, the valve being provided with a float guide means that guides the float to close the passage by means of a gap formed between an inner surface of the housing and an outer surface of the float that increases in size with increasing distance from the passage. 
     The guide means comprises a float tapered portion provided on the cuter surface of the float that tapers in with increasing distance from the passage, the tapered portion being provided from the outer peripheral edge at the passage end of the float, to where a plane that passes through the center of gravity of the float and is orthogonal to the float axis, intersects the outer surface of the float. The guide means can also be provided on the inner surface of the housing as a housing tapered portion that narrows the housing toward the passage end. 
     In another aspect of the invention, the float is provided with a pivot support portion at a junction between a float cylindrical surface and a float tapered portion, that is located at a point on the side face of the float intersected by a plane that passes through the center of gravity of the float and is orthogonal to the float axis, and the float tapered portion tapers in away from the passage end. The pivot support portion can be located at a junction between first and second float tapered portions constituting the float tapered portion. 
     The pivot support portion can be provided as a portion that extends around the whole peripheral surface, or it can be provided as a plurality of sections. When it is provided as a plurality of sections, a plurality of grooves can be used to divide the pivot support portion into a plurality of pivot support portions on the outer surface of the float. Alternatively, the pivot support portion can be divided into a plurality of pivot support portions by providing the outer surface of the float with a plurality of grooves extending parallel to the axis of the float. 
     As described above, in accordance with the present invention, a configuration is used in which the gap between the inner surface of the housing and the outer surface of the float is larger away from the passage than it is near the passage, which is used to guide the float toward the passage when the valve is turned onto its side. At the point at which the float abuts against the lower part of the angled surface forming the valve seat, or against the ceiling, since the distance between the center axis of the passage and the center axis of the valve head is smaller than in a prior art valve configuration, there is less frictional resistance between the float and the angled surface of the valve seat or the ceiling. Therefore, although the float is urged with the same spring force, the result is that the front of the float is lifted with a larger force than the force used to lift the float in the case of a prior art valve. Thus, the float can quickly close the passage, stopping any leakage of gasoline. 
     The invention also includes float provided with a pivot support portion about which the float can pivot. In this case, when the valve is turned onto its side, the force of the spring rotates the float as the float is urged forward to stop leakage of gasoline by closing the passage by abutting the valve head against the valve seat. 
     In accordance with another aspect, a plurality of grooves are provided around the outer surface of the float, with each groove extending axially with respect to the float. When the float reverts to its normal state, this arrangement prevents the float sticking to side walls. 
     The above and other objects, features and advantages of the present invention will become apparent from the following description made with reference to the accompanying drawings. 
    
    
     BRIEF EXPLANATION OF THE DRAWINGS 
     FIG. 1 shows a float used to form the valve of the present invention. 
     FIG. 2 is a cross-sectional view of a valve that uses the float of FIG. 1, according to a first embodiment of the invention. 
     FIG. 3 shows the valve of FIG. 2 turned sideways. 
     FIG. 4 is a cross-sectional view of a valve according to a second embodiment of the invention. 
     FIG. 5 shows the valve of FIG. 4 turned sideways. 
     FIG. 6 is a cross-sectional view of a valve according to a third embodiment of the invention. 
     FIG. 7 shows the valve of FIG. 6 turned sideways. 
     FIG. 8 shows a float used to form the valve of this invention. 
     FIG. 9 shows the float of FIG. 8 used in a valve turned sideways that is a fourth embodiment of the present invention. 
     FIG. 10 shows a float used to form the valve of this invention, with the right half thereof sectioned. 
     FIG. 11 shows the float of FIG. 10 used in a valve turned sideways that is a fifth embodiment of the present invention. 
     FIG. 12 shows a float used to form the valve of this invention, with the right half thereof sectioned. 
     FIG. 13 shows the float of FIG. 12 used in a valve turned sideways that is a sixth embodiment of the present invention. 
     FIG. 14 shows a float used to form the valve of this invention, with the right half thereof sectioned. 
     FIG. 15 shows the float of FIG. 14 used in a valve turned sideways that is a seventh embodiment of the present invention. 
     FIG. 16 shows a valve turned sideways that is an eighth embodiment of the invention. 
     FIG. 17 shows a float used to form the valve of this invention, with the right half thereof sectioned. 
     FIG. 18 shows the float of FIG. 17 used in a valve turned sideways that is a ninth embodiment of the present invention. 
     FIG.  19 ( a ) is a perspective view of an example of a float of the invention that is provided on its outer surface with a plurality of pivot support portions. 
     FIG.  19 ( b ) shows the float shown in FIG.  19 ( a ), with the right half thereof sectioned. 
     FIG. 20 is a cross-sectional view of a prior art valve. 
     FIG. 21 shows the valve of FIG. 20 turned sideways. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows the arrangement of a float forming the valve of this invention, FIG. 2 is a cross-sectional view of a first embodiment of the valve of the invention that uses the float shown in FIG. 1, and FIG. 3 shows the valve of FIG. 2 turned on its side. Parts that are the same as or equivalent to parts in FIG. 20 or  21  are given identical reference symbols, and further explanation thereof is omitted. 
     In FIGS. 1 to  3 , reference symbol  11 A denotes a float inside a housing  1 . The float  11 A is formed of synthetic resin and has a concave portion  12 , holes  13 , a valve head  14  and a guide means that, when the valve is turned sideways, guides the float so that the passage  3   a  is closed by the valve head  14 . The guide means comprises a tapered portion  15  on the outer surface of the float  11 A formed by a conical surface  15   a . The tapered portion narrows as the distance from the valve head  14  increases. Hence, the float  11 A is shaped like a truncated cone that narrows toward the cap  7  end. The outside two-dot chain line in FIG. 1 indicates the shape of the prior art float  11 . 
     The valve will now be described with reference to how it operates differently from the prior art valve when the vehicle in which it is used has turned over, therefore turning the valve on its side. 
     In order to allow smooth movement of the float  11 A, a clearance h is provided between the housing guide ribs  4   c  and the float  11 A. When the vehicle rolls over onto its side, as shown in FIG. 3, the center axis of the valve head  14  is displaced downward from the center axis of the passage  3   a . Since the float  11 A is truncated-conical, the gap between the centers of the valve head  14  and passage  3   a  becomes narrower at the valve head  14  end and wider at the cap  7  end. 
     Therefore, when the float  11 A is moved toward the passage  3   a  end by the force of the coil spring  21 , the valve head  14  is brought into contact with the angled surface at the lower end of the valve seat  3   b  and, because the distance between the center axes of the passage  3   a  and valve head  14  is less than in the case of the prior art configuration, there is less frictional resistance between the face of the valve seat  3   b  and the valve head  14 . Therefore, even with the urging force of the coil spring  21  being the same, the valve head  14  end is lifted with a larger force in the case of the float  11 A, enabling the passage  3   a  to be rapidly fully closed by the valve head  14 . Thus, gasoline leakage can be reduced and stopped. 
     FIG. 4 is a cross-sectional view of a second embodiment of the valve of the invention, and FIG. 5 shows the valve or FIG. 4 turned on its side. Parts that are the same as or equivalent to parts in FIGS. 1 to  3  or FIGS. 20 and 21 are given identical reference symbols, and further explanation thereof is omitted. In FIGS. 4 and 5, reference symbol  1 A denotes a synthetic resin housing comprised of a housing unit  2 A and a cap  7 . The housing unit  2 A has a ceiling  3  provided with a passage  3   a  and a valve seat  3   b , a side wall  4 A provided with holes  4   a , claws  4   b  and guide ribs  4   c , and guide means for guiding the float  11  so that the valve head  14  closes the passage  3   a  when the valve is turned on its side. There is also a connecting pipe  5  with a passage  5   a , and an annular mounting member  6 . 
     As shown in FIGS. 4 and 5, the guide means comprises a housing sloping portion  4   d  on the inner surface of the side wall  4 A that slopes inward going toward the passage  3   a  end. The sloping portion  4   d  can be replaced by the guide ribs  4   c  positioned at set intervals that are angled inward as they rise up toward the passage  3   a.    
     The valve will now be described with reference to how it operates differently from the prior art valve when the vehicle in which it is used has rolled over, turning the valve on its side. 
     To ensure smooth movement of the float  11 , a clearance (h) is provided between the guide ribs  4   c  and the float  11 A. Therefore, when the vehicle rolls over onto its side, as shown in FIG. 5, the center axis of the valve head  14  is displaced downward from the center axis of the passage  3   a . The sloping portion  4   d  on the side wall  4 A means that the distance between the center axes of the valve head  14  and passage  3   a  is smaller at the valve head  14  end and larger at the cap  7  end. Consequently, when the float  11  is moved toward the passage  3   a  by the force of the coil spring  21 , bringing the valve head  14  into contact with the angled surface at the lower end of the valve seat  3   b , since the distance between the center axes of the passage  3   a  and valve head  14  is less than in the case of the prior art configuration, there is less frictional resistance between the face of the valve seat  3   b  and the valve head  14 . Therefore, even with the urging force of the coil spring  21  being the same, the valve head  14  end of the float  11  can be lifted with a larger force, enabling the passage  3   a  to be speedily closed by the valve head  14 . Thus, gasoline leakage can be reduced and stopped. 
     FIG. 6 is a cross-sectional view of a third embodiment of the valve of the invention, and FIG. 7 shows the valve of FIG. 6 turned on its side. Parts that are the same as or equivalent to parts in FIGS. 1 to  5  or FIGS. 20 and 21 are given identical reference symbols, and a further explanation thereof is omitted. 
     The valve will now be described with reference to how it operates differently from the prior art valve when the vehicle in which it is used has rolled over, turning the valve on its side. 
     To ensure smooth movement of the float  11 , a clearance h is provided between the guide ribs  4   c  and the float  11 A. Therefore, when the vehicle rolls over onto its side, as shown in FIG. 7, the center axis of the valve head  14  is displaced downward from the center axis of the passage  3   a . Since the float  11 A is in the shape of a truncated cone, with the smaller end toward the cap  7 , the distance between the center axes of the valve head  14  and passage  3   a  is smaller at the valve head  14  end and larger at the cap  7  end. As such, when the float  11  is moved toward the passage  3   a  by the force of the coil spring  21 , bringing the valve head  14  into contact with the angled surface at the lower end of the valve seat  3   b , since the distance between the center axes of the passage  3   a  and valve head  14  is less than in the case of the prior art configuration, there is less frictional resistance between the face of the valve seat  3   b  and the valve head  14 . Therefore, even with the urging force of the coil spring  21  being the same, the valve head  14  end of the float  11 A can be lifted with a larger force, enabling the passage  3   a  to be speedily closed by the valve head  14 . Gasoline leakage therefore can be reduced and stopped. 
     FIG. 8 illustrates a valve float of this invention, and FIG. 9 shows the float of FIG. 8 used in a valve turned on its side that is a fourth embodiment of the invention. Parts that are the same as or equivalent to parts in FIGS. 1 to  7  or FIGS. 20 and 21 are given identical reference symbols, and further explanation thereof is omitted. In FIGS. 8 and 9, reference symbol  2 B denotes a synthetic resin housing comprising a housing unit  2 B and a cap  7 . The housing unit  2 B comprises a hemispherical ceiling  3 B with a passage  3   a , a side wall  4 B with holes  4   a  and claws  4   b , a connecting pipe  5  with a passage  5   a , and an annular mounting member  6 . In FIGS. 8 and 9, reference symbol  11 B denotes a float inside the housing  1 B. The float  11 B is cylindrical in shape and formed of synthetic resin with a concave portion  12  and holes  13 . It has a hemispherical top, and a guide means that, when the valve is turned on its side, guides the float so that the hemispherical top closes the passage  3   a.    
     As shown in FIG. 8, the guide means is comprised of a float tapered portion  15  whereby the outer surface of the float  11 B tapers in from the upper end. The valve will now be described with reference to how it operates differently from the prior art valve when the vehicle in which it is used has rolled over, turning the valve on its side. To ensure smooth movement of the float  11 B, a clearance (h) is provided between the side wall  4 B and the float  11 B. As a result, when the vehicle rolls over onto its side, tilting the valve onto its side, as shown in FIG. 9, the center axis of the float  11 B is displaced downward from the center axis of the passage  3   a . Since the float  11 B tapers down in size toward the cap  7 , the distance between the center axes is smaller at the top end of the float  11 B and larger at the cap  7  end. Therefore, when the float  11 B is moved toward the passage  3   a  by the force of the coil spring  21 , bringing the lower part of the float top into contact with the lower part of the ceiling  3 B, since the distance between the center axes of the passage  3   a  and valve head  14  is less than in the case of a prior art configuration, there is less frictional resistance between the ceiling  3 B and the float  11 B. Therefore, even with the urging force of the coil spring  21  being the same, the float  11 B can be forced up to the passage  3   a , making it possible to speedily close the passage  3   a . Gasoline leakage therefore can be reduced and stopped. 
     FIG. 10 illustrates a valve float of the invention, with the right half shown in cross-section, and FIG. 11 shows the float of FIG. 10 used in a valve turned on its side according to a fifth embodiment of the invention. Parts that are the same as or equivalent to parts in FIGS. 1 to  9  or FIGS. 20 and 21 are given identical reference symbols, and further explanation thereof is omitted. 
     In FIGS. 10 and 11, reference symbol  11 C denotes a float inside the housing  1 . The float  11 C is formed of synthetic resin and is provided with the above-described concave portion  12 , holes  13  and valve head  14 . It also has guide means that, when the valve is turned on its side, guides the float to close the passage  3   a  with the valve head  14 . As shown in FIG. 10, the guide means is comprised of a float tapered portion  15 C that tapers in the outer surface of the float  11 C from the upper end; the float tapered portion  15 C is comprised of conical surfaces  15   a  and  15   b . The junction (pivot support portion) F between the conical surfaces  15   a  and  15   b  is located at a point on the side face of the float  11 C intersected by a plane P that is parallel to, and on the upper side of, a plane H that passes through the center of gravity G of the float  11 C and is orthogonal to the axis X of the float  11 C. Thus, in shape the float  11 C is formed by joining together two truncated cones that taper down toward the cap  7  end. In FIG. 10, the two-dot chain line indicates the shape of the prior art float  11 , and the one-dot chain line indicates an extension of the conical surface  15   a . The end of the float tapered portion  15 C on the passage  3   a  side, that is, the conical surface  15   a  end, is located on the largest-diameter outer peripheral edge on the passage  3   a  side. 
     The valve will now be described with reference to how it operates differently from the prior art valve when the vehicle in which it is used has rolled over, turning the valve on its side. A clearance (h) is provided between the guide ribs  4   c  and the float  11 C to allow the float  11 C to move smoothly. Therefore, if the vehicle rolls over onto its side, as shown in FIG. 11, the center axis of the valve head  14  is displaced down from the center axis of the passage  3   a  by the amount of the clearance (h). At this time, because the center of gravity G is to the right of the junction F, the conical surface  15   b  of the float  11 C contacts the guide ribs  4   c . Also, since the float  11 C is narrower toward the cap  7  end, the center axes of the valve head  14  and passage  3   a  intersect slightly to the right of the passage  3   a  and are closer together at the top end of the float  11 C than at the cap end. 
     Therefore, when the float  11 C is urged toward the passage  3   a  by the force of the coil spring  21 , the valve head  14  is brought into contact with the upper part of the angled surface forming the valve seat  3   b , and under the urging of the coil spring  21 , the float  11 C is turned counterclockwise about the junction F as it is moved toward the passage  3   a . Therefore, even though the urging force of the coil spring  21  is the same, the operation of closing the passage  3   a  with the valve head  14  is effected more rapidly than in the case of the prior art or the first four embodiments, enabling leakage of gasoline to be reduced and stopped. 
     FIG. 12 illustrates a valve float of the invention, with the right half shown in cross-section, and FIG. 13 shows the float of FIG. 12 used in a valve turned on its side according to a sixth embodiment of the invention. Parts that are the same as or equivalent to parts in FIGS. 1 to  11  or FIGS. 20 and 21 are given identical reference symbols, and further explanation thereof is omitted. 
     In FIGS. 12 and 13, reference symbol  11 D denotes a float inside a housing  1 . The float  11 D is formed of synthetic resin and has a concave portion  12 , holes  13 , a valve head  14 , and a guide means that, when the valve is turned sideways, guides the float to close the passage  3   a  with the valve head  14 . As shown in FIG. 12, the guide means is comprised of a float tapered portion  15 D that tapers in the outer surface of the float  11 D from the upper end. The float tapered portion  15 D is comprised of conical surfaces  15   a  and  15   b . The junction (pivot support portion) F between the conical surfaces  15   a  and  15   b  is located at a point on the side face of the float  11 D intersected by a plane Q that is parallel to, and on the lower side of, a plane H that passes through the center of gravity G of the float  11 D and is orthogonal to the axis X of the float  11 D. Thus, in shape the float  11 D is formed by joining together two truncated cones that taper down toward the cap  7  end. The two-dot chain line indicates the shape of the prior art float  11 , and the one-dot chain line indicates an extension of the conical surface  15   a . The end of the float tapered portion  15 D on the passage  3   a  side, that is, the conical surface  15   a  end, is located on the largest-diameter outer peripheral edge on the passage  3   a  side. 
     The valve will now be described with reference to how it operates differently from the prior art valve when the vehicle in which it is used has rolled over, turning the valve on its side. A clearance (h) is provided between the guide ribs  4   c  and the float  11 D to allow the float  11 D to move smoothly. Therefore, if the vehicle rolls over onto its side, as shown in FIG. 13, the center axis of the valve head  14  is displaced downward from the center axis of the passage  3   a  by the amount of the clearance (h). At this time, because the center of gravity G is above or to the left of the junction F, the conical surface  15   a  of the float  11 D contacts the guide ribs  4   c . Since the float  11 D is narrower toward the cap  7  end, the gap between the center axes of the float  11 D and passage  3   a  is smaller toward the valve head  14  end and larger at the cap  7  end. 
     Therefore, when the float  11 D is moved toward the passage  3   a  by the force of the coil spring  21 , the valve head  14  comes into contact with the lower part of the angled surface forming the valve seat  3   b , and under the urging of the coil spring  21 , the float  11 D is turned clockwise about the junction F as it is moved toward the passage  3   a . Therefore, even though the urging force of the coil spring  21  is the same, the operation of closing the passage  3   a  with the valve head  14  is effected more rapidly than in the case of the prior art or the first four embodiments, enabling leakage of gasoline to be reduced and stopped. 
     FIG. 14 illustrates a valve float according to the invention, with the right half shown in cross-section, and FIG. 15 shows the float of FIG. 14 used in a valve turned on its side according to a seventh embodiment of the invention. Parts that are the same as or equivalent to parts in FIGS. 1 to  13  or FIGS. 20 and 21 are given identical reference symbols, and further explanation thereof is omitted. 
     In FIGS. 14 and 15, reference symbol  11 E denotes a float inside a housing  1 . The float  11 E is formed of synthetic resin and has a concave portion  12 , holes  13 , a valve head  14 , and a guide means that, when the valve is turned sideways, guides the float to close the passage  3   a  with the valve head  14 . As shown in FIG. 14, the guide means is comprised of a float tapered portion  15 E that comprises a cylindrical surface  15   c  provided on the outer surface of the float  11 E and a conical surface  15   d  that tapers the float  11 E in from the end of the cylindrical surface  15   c . The junction (pivot support portion) F between the cylindrical surface  15   c  and the conical surface  15   d  is located at a point on the side face of the float  11 E intersected by a plane P that is parallel to, and on the upper side of, a plane H that passes through the center of gravity G of the float  11 E and is orthogonal to the axis X of the float  11 E. Thus, the float  11 E is in the shape of a cylinder joined to a truncated cone that tapers in toward the cap end. 
     The valve will now be described with reference to how it operates differently from the prior art valve when the vehicle in which it is used has rolled over, turning the valve on its side. A clearance (h) is provided between the guide ribs  4   c  and the float  11 E to allow the float  11 E to move smoothly. Therefore, if the vehicle rolls over onto its side, as shown in FIG. 15, the center axis of the valve head  14  is displaced downward from the center axis of the passage  3   a  by the amount of the clearance (h). As the center of gravity G is to the right of the junction F, the conical surface  15   d  of the float  11 E comes into contact with the guide ribs  4   c . Since the float  11 E is narrower toward the cap  7  end, the center axes of the float  11 E and passage  3   a  intersect slightly to the right of the passage  3   a , and the gap between the two axes becomes narrower at the valve head  14  end and wider at the cap  7  end. 
     Therefore, when the float  11 E is moved toward the passage  3   a  by the force of the coil spring  21  and the valve head  14  comes into contact with the upper part of the angled surface of the valve seat  3   b , under the urging force of the coil spring  21  the float  11 E is turned counterclockwise about the junction F as it advances toward the passage  3   a . Therefore, even though the urging force of the coil spring  21  may be the same, the operation of closing the passage  3   a  with the valve head  14  is effected more rapidly than in the case of the prior art or the first four embodiments, enabling leakage of gasoline to be reduced and stopped. 
     FIG. 16 shows a valve turned on its side that is an eighth embodiment of the invention. Parts that are the same as or equivalent to parts in FIGS. 1 to  15  or FIGS. 20 and 21 are given identical reference symbols, and further explanation thereof is omitted. 
     The valve will now be described with reference to how it operates differently from the prior art valve when the vehicle in which it is used has rolled over, turning the valve on its side. A clearance (h) is provided between the guide ribs  4   c  and the float  11 E to allow the float  11 E to move smoothly. Therefore, if the vehicle rolls over onto its side, as shown in FIG. 16, the center axis of the valve head  14  is displaced downward from the center axis of the passage  3   a  by the amount of the clearance (h). As the center of gravity G is to the right of the junction F, the conical surface  15   d  of the float  11 E comes into contact with the guide ribs  4   c . Since the float  11 E is narrower toward the cap  7  end, the center axes of the float  11 E and passage  3   a  intersect slightly to the right of the passage  3   a , and the gap between the two axes becomes narrower at the front end of the float  11 E and wider at the cap  7  end. 
     Therefore, when the float  11 E is moved toward the passage  3   a  by the force of the coil spring  21 , the valve head  14  comes into contact with the upper part of the angled surface of the valve seat  3   b , and under the urging force of the coil spring  21  the float  11 E turns counterclockwise about the junction F as it moves toward the passage  3   a . Thus, even though the urging force of the coil spring  21  may be the same, the operation of closing the passage  3   a  with the valve head  14  is effected more rapidly than in the case of the prior art or the first four embodiments, enabling leakage of gasoline to be reduced and stopped. 
     FIG. 17 illustrates a valve float according to the invention, with the right half shown in cross-section, and FIG. 18 shows the float of FIG. 17 used in a valve turned on its side that is a ninth embodiment of the invention. Parts that are the same as or equivalent to parts in FIGS. 1 to  16  or FIGS. 20 and 21 are given identical reference symbols, and further explanation thereof is omitted. 
     In FIGS. 17 and 18, reference symbol  11 F denotes a float inside a housing  1 . The float  11 F is formed of synthetic resin and has a concave portion  12 , holes  13 , a valve head  14 , and a projecting ridge  15   e  around the cylindrical surface  15   c , the ridge  15   e  constituting a pivot support portion. The ridge  15   e  is located at a point on the side face of the float  11 F intersected by a plane P that is parallel to, and on the upper side of, a plane H that passes through the center of gravity G of the float  11 C and is orthogonal to the axis X of the float  11 F. 
     The valve will now be described with reference to how it operates differently from the prior art valve when the vehicle in which it is used has rolled over, turning the valve on its side. A clearance (h) is provided between the guide ribs  4   c  and the float  11 F to allow the float  11 F to move smoothly. Therefore, if the vehicle rolls over onto its side, as shown in FIG. 18, the center axis of the valve head  14  is displaced downward from the center axis of the passage  3   a . As the center of gravity G is to the right of the ridge  15   e , the ridge  15   e  of the float  11 F contacts the guide ribs  4   c  and guide ribs  8   b . Because of the housing sloping portion  4   d  on the side wall  4 A, the center axes of the valve head  14  and passage  3   a  intersect slightly to the right of the passage  3   a , and the gap between the two axes becomes narrower at the valve head  14  end and wider at the cap  7  end. 
     Therefore, when the float  11 F is moved toward the passage  3   a  by the force of the coil spring  21 , the valve head  14  comes into contact with the upper part of the angled surface of the valve seat  3   b , and under the urging force of the coil spring  21  the float  11 F turns counterclockwise about the ridge  15   e  as it moves toward the passage  3   a . Thus, even though the urging force of the coil spring  21  may be the same, the operation of closing the passage  3   a  with the valve head  14  is effected more rapidly than in the case of the prior art or the first four embodiments, enabling leakage of gasoline to be reduced and stopped. 
     FIG.  19 ( a ) is a perspective view of an example of a float of the invention that is provided on its outer surface with a plurality of pivot support portions; FIG.  19 ( b ) is a view of the float with the right half shown in cross-section. Parts that are the same as or equivalent to parts in FIGS. 1 to  18  or FIGS. 20 and 21 are given identical reference symbols, and further explanation thereof is omitted. 
     In FIGS.  19 ( a ) and  19 ( b ), reference symbol  11 G denotes a float. The float  11 G is formed of synthetic resin and has a concave portion  12 , holes  13  and a valve head  14 . The float  11 G also has a guide means  15 E that, when the valve is turned onto its side, guides the float to close the passage  3   a  with the valve head  14 . The float  11 G also has a plurality of grooves  15   f  that divide junction F into a plurality of pivot support portions. The grooves  15   f  are provided at set intervals around the outer surface of the float  11 G, each groove  15   f  extending axially along the float. The grooves  15   f  are each narrower than the guide ribs  4   c  and  8   b  of the housing, to prevent the ribs from being accommodated within the grooves. The valve constituted using the float  11 G can be used to the same effect as the valves of the first to ninth embodiments. When the float  11 G reverts to its normal state, the grooves  15   f  prevent the float sticking to the side wall  4 ,  4 A or  4 B of the housing, allowing the float to revert to its normal state more quickly. When the junction F is divided into a plurality of sections, it is preferable for the grooves to extend axially along the float, but not essential. 
     In the case of the fifth embodiment shown in FIGS. 10 and 11 and the sixth embodiment shown in FIGS. 12 and 13, the housing  1  can be changed to housing  1 A without changing the effect provided by the invention. In the case of the seventh and eighth embodiments shown in FIGS. 14 to  16 , the same effect can be obtained even if the float  11 E having the junction (pivot support portion) F between the cylindrical surface  15   c  and the conical surface  15   d  is changed to the float  11 D of FIG. 12 having the junction F located at a point on the side face of the float intersected by a plane Q that is parallel to, and on the lower side of, a plane H that passes through the center of gravity G of the float and is orthogonal to axis X of the float. In the ninth embodiment shown in FIGS. 17 and 18, the same effect is provided even if the position of the ridge  15   e  is changed to that of the junction F shown in FIG.  12 . Also, while in the ninth embodiment the pivot support portion is formed as a ridge  15   e  around the peripheral surface, the ridge  15   e  can instead be formed as a non-continuous plurality of sections around the peripheral surface, in which case it is preferable for the spaces between the ridge  15   e  sections to be smaller than the width of the guide ribs  4   c  and  8   b , so that the ribs cannot enter the spaces. 
     As described in the foregoing, in accordance with the present invention, a configuration is used in which the gap between the inner surface of the housing and the outer surface of the float is larger away from the passage than it is near the passage, which is provided as a float guide means. Therefore, when the valve is turned on its side, the guide means guides the float toward the passage. At the point at which the float abuts against the lower part of the angled surface forming the valve seat, or against the ceiling, since the distance between the center axis of the passage and the center axis of the valve head is smaller than in the prior art configuration, there is less frictional resistance between the float and the angled surface of the valve seat or the ceiling. 
     Therefore, although the float is urged with the same spring force, the result is that the front of the float is lifted with a larger force than the force used to lift the float in the case of a prior art valve arrangement. Thus, the float is able to quickly close the passage, shutting off any leakage of gasoline. 
     The invention also includes a configuration in which the float is provided with a pivot support portion about which the float can pivot. In this case, under a spring force, the float is rotated as it is urged forward to abut the valve head against the valve seat, to thereby rapidly close the passage and stop leakage of gasoline. In accordance with another aspect, a plurality of grooves is provided around the outer surface of the float, with each groove extending axially with respect to the float. When the float reverts to its normal state, this arrangement prevents the float sticking to the side wall.