Patent Publication Number: US-2023144508-A1

Title: Fill-up restriction valve

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on Japanese Patent Application No. 2021-182253 filed on Nov. 9, 2021, the contents of which are incorporated herein by way of reference. 
     TECHNICAL FIELD 
     The present invention relates to a fill-up restriction valve that suppresses excessive refueling to a fuel tank. 
     BACKGROUND 
     A fuel tank may be provided with a fill-up restriction valve that detects fill-up at the time of refueling and closes to suppress excessive refueling. 
     An example of this type of valve includes an exhaust valve device of a fuel tank described in Patent Literature 1. The exhaust valve device includes a cylindrical upper structure having a passage therein that communicates inside and outside of the fuel tank, a lower structure including a float support piece protruding from an inner peripheral surface and an upper end portion into which a lower end portion of the upper structure is fitted, and a float valve supported between the upper structure and the float support piece in a manner of being movable up and down and configured to close the passage. The upper structure includes a plurality of first locking claws protruding on an outer peripheral surface of the lower end portion fitted into the lower structure. The lower structure has a plurality of first locking holes with which the plurality of first locking claws engage, respectively. 
     The lower structure includes, in order from an upper end, a ring portion having a constant diameter, a tapered portion having a diameter decreasing downward, an intermediate portion having a constant diameter and formed with a first locking hole, and a skirt portion having a lower opening. The intermediate portion of the lower structure has, in an inner periphery thereof, a fitting groove into which the lower end portion of the upper structure is fitted. 
     Since the first locking claws of the upper structure are engaged with the first locking holes of the lower structure, and the lower end portion of the upper structure is fitted and inserted into the fitting groove of the lower structure, the upper structure is joined to the lower structure. When a fuel liquid level is located in the lower opening of the skirt portion of the lower structure by refueling to the fuel tank, air in the fuel tank is restricted from being discharged, so that the fill-up is restricted. 
     Patent Literature 1: JP5767947B 
     In the exhaust valve device of Patent Literature 1, a fitting portion between the lower end portion of the upper structure and the fitting groove of the lower structure is located above the lower opening of the skirt portion of the lower structure that serves as a fill-up detection opening. For this reason, when the sealing performance of the fitting portion deteriorates and air escapes from the fitting portion, the fill-up may not be restricted at a predetermined fuel liquid level and the fill-up detection accuracy may deteriorate. 
     Therefore, an object of the present invention is to provide a fill-up restriction valve that can improve sealing performance between a housing body and a lower cap and improve fill-up detection accuracy. 
     SUMMARY 
     There is provided a fill-up restriction valve including: a housing, in which a valve chamber configured to communicate with inside of a fuel tank is provided on a lower side by a partition wall, a ventilation chamber configured to communicate with outside of the fuel tank is provided on an upper side by the partition wall, and an opening configured to communicate the valve chamber with the ventilation chamber is formed in the partition wall; and a float valve accommodated in the valve chamber in a manner of being movable up and down, the float valve configured to close the opening when a fuel liquid level rises to a predetermined height during refueling into the fuel tank. The housing includes a housing body including a body-side peripheral wall, and a lower cap including a cap-side peripheral wall, the lower cap being installed to a lower side of the housing body by a joint portion. The joint portion includes an annular groove provided in one of an upper end portion of the cap-side peripheral wall and a lower end portion of the body-side peripheral wall, an insertion wall portion provided on the other one of the upper end portion of the cap-side peripheral wall and the lower end portion of the body-side peripheral wall, the insertion wall portion configured to be inserted into the annular groove, and an annular protrusion formed on one of the insertion wall portion and the annular groove, or an annular seal member disposed between the insertion wall portion and the annular groove. The annular protrusion or the annular seal member is configured to be in pressure-contact with the annular groove and the insertion wall portion in a state where the insertion wall portion is inserted into the annular groove. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is an exploded perspective view showing an embodiment of a fill-up restriction valve according to the present invention. 
         FIG.  2    is a perspective view of the fill-up restriction valve. 
         FIG.  3    is a side view of the fill-up restriction valve. 
         FIG.  4    is a cross-sectional view taken along a line A-A of  FIG.  2   . 
         FIG.  5    is an enlarged perspective view of a housing body constituting a housing of the fill-up restriction valve when viewed from a direction different from that of  FIG.  1   . 
         FIG.  6    is an enlarged perspective view of a lower cap constituting the housing of the fill-up restriction valve when viewed from a direction different from that of  FIG.  1   . 
         FIG.  7 A  is an enlarged sectional view of a main portion in a state where the housing body and the lower cap are installed, and  FIG.  7 B  is an enlarged sectional view of a main portion in a state before the housing body and the lower cap are installed. 
         FIG.  8    is a cross-sectional schematic view of the fill-up restriction valve in a state where fill-up restriction is performed. 
         FIG.  9 A  is an enlarged cross-sectional view of a first modification of a joint portion of the fill-up restriction valve, and  FIG.  9 B  is an enlarged cross-sectional view of a second modification of the joint portion of the fill-up restriction valve. 
         FIG.  10    is a side view showing another embodiment of a fill-up restriction valve according to the present invention. 
         FIG.  11    is a cross-sectional view of the fill-up restriction valve. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment of Fill-Up Restriction Valve 
     Hereinafter, an embodiment of a fill-up restriction valve according to the present invention will be described with reference to the drawings. 
     As shown in  FIGS.  1  to  4   , a fill-up restriction valve  10  in the embodiment includes a housing  15  and a float valve  70 . In the housing  15 , a valve chamber V communicating with inside of a fuel tank is provided on a lower side by a partition wall  22 , a ventilation chamber R communicating with outside of the fuel tank is provided on an upper side by the partition wall  22 , and an opening  23  communicating the valve chamber V with the ventilation chamber R is formed in the partition wall  22 . The float valve  70  is accommodated in the valve chamber V in a manner of being movable up and down, and closes the opening  23  when a fuel liquid level rises to a predetermined height at the time of refueling the inside of the fuel tank. 
     The housing  15  in the embodiment further includes a housing body  20  including a body-side peripheral wall  21 , a lower cap  40  including a cap-side peripheral wall  41  and installed to a lower side of the housing body  20  by a joint portion, and an upper cover  60  installed to the housing body  20 . The fill-up restriction valve  10  further includes, between the lower cap  40  and the float valve  70 , a biasing spring S that biases the float valve  70 . 
     In the embodiment, as shown in  FIGS.  4  and  7   , the joint portion that installs the lower cap  40  to the lower side of the housing body  20  includes an annular groove  46  provided in an upper end portion of the cap-side peripheral wall  41 , an insertion wall portion  33  provided on a lower end portion of the body-side peripheral wall  21  and inserted into the annular groove  46 , and an annular protrusion  35  formed on an outer side surface  33   a  of the insertion wall portion  33 . In a state where the insertion wall portion  33  is inserted into the annular groove  46 , the annular protrusion  35  is in pressure-contact with the annular groove  46  and the insertion wall portion  33 . 
     In the following description, “fuel” means liquid fuel (including droplets of fuel), and “fuel vapor” means evaporated fuel. 
     First, the housing body  20  will be described with reference to  FIGS.  1 ,  4 ,  5   , and the like. 
     The housing body  20  includes the body-side peripheral wall  21  having a substantially cylindrical shape, and above the body-side peripheral wall  21 , the partition wall  22  having a substantially disc shape is disposed. The partition wall  22  is formed with the opening  23  at a center thereof in the radial direction. The opening  23  is formed with a plurality of ribs  23   a  on an inner side thereof, so that the opening  23  has a lattice hole shape by the ribs  23   a . The body-side peripheral wall  21  includes a flange portion  24  projecting from an upper outer periphery thereof. The flange portion  24  is formed with a ring install groove  25   a  on an inner side thereof, and an annular seal ring  25  is attached to the ring install groove  25   a  (see  FIG.  4   ). 
     As shown in  FIGS.  4  and  5   , the body-side peripheral wall  21  is provided with a first annular projection  26  projecting from an intermediate position in an axial direction on an outer periphery thereof. The body-side peripheral wall  21  is further provided with a second annular projection  27  projecting from a position closer to an axially lower end than the first annular projection  26  on the outer periphery thereof (see  FIG.  4   ). As shown in  FIG.  7 A , in a state where the housing body  20  and the lower cap  40  are installed, the first annular projection  26  is disposed with a predetermined gap from an upper end of an outer peripheral wall  44  provided on the upper end portion of the cap-side peripheral wall  41 , and the second annular projection  27  is adjacent to an inner side of the upper end of the outer peripheral wall  44 . 
     As shown in  FIGS.  1  and  5   , the body-side peripheral wall  21  is further provided with a plurality of cap-side engagement protrusions  28  protruding at equal intervals in the circumferential direction from positions lower than the second annular projection  27  on the outer periphery of the body-side peripheral wall  21 . The body-side peripheral wall  21  is further provided with a plurality of cover-side engagement protrusions  29  that protrude on positions above the first annular projection  26  and aligning with the plurality of cap-side engagement protrusions  28  on the outer periphery of the body-side peripheral wall  21 . 
     As shown in  FIG.  1   , the second annular projection  27  is provided with a pair of positioning protrusions  30 ,  30  protruding on a part of an outer periphery thereof. 
     As shown in  FIGS.  1  and  3   , the body-side peripheral wall  21  is further formed with a communication hole  31  at two positions facing each other in the radial direction on an upper end portion side thereof. The communication hole  31  communicates the inside of the fuel tank with the inside of the valve chamber V. The communication hole  31  is a portion that is constantly maintained in a state of not being submerged except when a vehicle overturns, and flows air in the fuel tank into the valve chamber V. 
     As shown in  FIG.  5   , the body-side peripheral wall  21  is provided with guide ribs  32  extending in the axial direction at equal intervals in the circumferential direction on an inner periphery thereof. The guide ribs  32  guide an upward and downward movement of the float valve  70 . 
     The body-side peripheral wall  21  is provided with, on the axially lower end portion, the insertion wall portion  33  that is inserted into the annular groove  46  provided in the upper end portion of the cap-side peripheral wall  41 . 
     More specifically, as shown in  FIG.  7 A , the body-side peripheral wall  21  is formed with a stepped portion  33   c  having a stepped shape on an inner side of the axially lower end portion. The insertion wall portion  33  is displaced radially outward relative to the body-side peripheral wall  21  by the stepped portion  33   c  and extends downward. The insertion wall portion  33  is formed in a substantially cylindrical shape similarly to the body-side peripheral wall  21 , and has a thickness (a length between the outer side surface  33   a  on the outer diameter side and an outer side surface  33   b  on the inner diameter side) smaller than a groove width of the annular groove  46  (a length between an inner side surface  46   a  on the outer diameter side and an inner side surface  46   b  on the inner diameter side). 
     Further, the insertion wall portion  33  is provided with a rounded R-shaped portion  34  on an outer periphery of a lowermost end thereof (see  FIG.  7 B ), so that the insertion of the insertion wall portion  33  into the annular groove  46  is facilitated. 
     The insertion wall portion  33  is provided with an annular protrusion  35  at a position above the rounded R-shaped portion  34  at the lowermost end on the outer side surface  33   a  (the outer side surface  33   a  on the outer diameter side) located on the radially outer side of the insertion wall portion  33 . The annular protrusion  35  continuously protrudes and extends in an annular shape (a shape that is not interrupted in the middle of the circumferential direction) along an outer periphery of the insertion wall portion  33 . As shown in  FIG.  7 B , the annular protrusion  35  has a rounded curved shape in cross section, and a top portion thereof is in pressure-contact with the inner side surface  46   a  on the outer diameter side of the annular groove  46 . 
     In a state where the insertion wall portion  33  is inserted into the annular groove  46 , a gap G1 is defined between the outer side surface  33   a  of the insertion wall portion  33  and the annular groove  46  at a position above the annular protrusion  35 . It can also be said that, in a state where the annular protrusion  35  is in pressure-contact with the inner side surface  46   a  on the outer diameter side of the annular groove  46 , the gap G1 is defined at a position above the pressure-contact portion (the portion where the top portion of the annular protrusion  35  is in pressure-contact with the inner side surface  46   a  of the annular groove  46 ). More specifically, the gap G1 is defined between the inner side surface  46   a  on the outer diameter side of the annular groove  46  and the outer side surface  33   a  on the outer diameter side of the insertion wall portion  33  at a position above the annular protrusion  35  (a position above the pressure-contact portion of the top portion of the annular protrusion  35  and the inner side surface  46   a  of the annular groove  46 ). The liquid fuel oscillated in the fuel tank accumulates in the gap G1 (see  FIG.  7 A ). 
     Further, as shown in  FIG.  7 B , a dimension L1 from a predetermined position P of the valve chamber V (here, a position aligned with the inner side surface  46   b  on the inner diameter side of the annular groove  46 ) to the top portion of the annular protrusion  35  is larger than a dimension L2 from the predetermined position P of the valve chamber V to the inner side surface  46   a  on the outer diameter side of the annular groove  46 . As a result, when the insertion wall portion  33  is inserted into the annular groove  46 , the annular protrusion  35  is pressed against the inner side surface  46   a  on the outer diameter side of the annular groove  46 , and the insertion wall portion  33  is inserted into the annular groove  46  while being slightly flexibly deformed inward in the radial direction of the valve chamber V. 
     In the state where the insertion wall portion  33  is inserted into the annular groove  46 , a lower end of the insertion wall portion  33  does not abut against a bottom surface  46   c  of the annular groove  46  (see  FIG.  7 A ). 
     As shown in  FIG.  7 A , the body-side peripheral wall  21  is formed with a recessed groove  37  at a position above the gap G1 on an outer side surface  21   a  thereof. The recessed groove  37  communicates with the gap G1. In the embodiment, the recessed groove  37  is formed in the outer side surface  21   a  (the outer side surface  21   a  on the outer diameter side) located on the radially outer side at the axially lower end portion of the body-side peripheral wall  21 . The recessed groove  37  is a groove that extends at a constant width and has a constant depth to form an annular shape continuous along the circumferential direction of the body-side peripheral wall  21 . 
     Next, the lower cap  40  installed to the lower side of the housing body  20  will be described with reference to  FIGS.  1 ,  4 ,  6   , and the like. 
     The lower cap  40  is formed in a bottomed cap shape and includes the cap-side peripheral wall  41  having a substantially cylindrical shape and a spring support plate  53  disposed at a lower bottom portion of the cap-side peripheral wall  41 . As shown in  FIGS.  7 A and  7 B , the cap-side peripheral wall  41  is provided with an annular wall  43  annularly extending in an outer diameter direction on the upper end portion thereof, an outer peripheral wall  44  having a substantially cylindrical shape and erected from an outer peripheral edge portion of the annular wall  43 . and an inner peripheral wall  45  having a substantially cylindrical shape and erected radially inward of the outer peripheral wall  44 , thereby forming a double cylindrical wall. The annular groove  46  having an annular shape is provided between the outer peripheral wall  44  and the inner peripheral wall  45 . The annular groove  46  has the inner side surface  46   a  (the inner side surface  46   a  on the outer diameter side) located on the radially outer side of the cap-side peripheral wall  41 , the inner side surface  46   b  (the inner side surface  46   b  on the inner diameter side) located on the radially inner side of the cap-side peripheral wall  41 , and the bottom surface  46   c . 
     As described above, the insertion wall portion  33  is inserted into the annular groove  46 , and the annular protrusion  35  is in pressure-contact with the inner side surface  46   a  on the outer diameter side of the annular groove  46 . In this state, a gap G2 is defined between the inner side surface  46   b  on the inner diameter side of the annular groove  46  and the outer side surface  33   b  (the outer side surface  33   b  on the inner diameter side) located on the radially inner side of the insertion wall portion  33 , between the bottom surface  46   c  of the annular groove  46  and the lower end of the insertion wall portion  33 , and between the inner side surface  46   a  on the outer diameter side of the annular groove  46  and the outer side surface  33   a  on the outer diameter side of the insertion wall portion  33  at a position below the pressure-contact portion of the top portion of the annular protrusion  35  and the inner side surface  46   a  of the annular groove  46  (see  FIG.  7 A ). Even when the liquid fuel accumulates in the gap G1, the top portion of the annular protrusion  35  is in pressure-contact with the inner side surface  46   a  of the annular groove  46  and seals the outer side surface  33   a  of the insertion wall portion  33  and the inner side surface  46   a  of the annular groove  46 , so that the liquid fuel does not flow into the gap G2. 
     As shown in  FIGS.  7 A and  7 B , the outer peripheral wall  44  provided on the upper end portion of the cap-side peripheral wall  41  is thicker than the inner peripheral wall  45  and extends upward longer than the inner peripheral wall  45 . The outer peripheral wall  44  includes a base portion  44   a  erected substantially parallel to the inner peripheral wall  45 , and an extending portion  44   b  that enlarges in diameter in the outer diameter direction from an upper end of the base portion  44   a  by tapered portions  47 ,  48  and extends upward. The tapered portion  47  located on the radially inner side of the outer peripheral wall  44  is formed at a position aligned with the recessed groove  37  provided in the body-side peripheral wall  21  in a state where the insertion wall portion  33  is inserted into the annular groove  46 . 
     As shown in  FIGS.  7 A and  7 B , the cap-side peripheral wall  41  is formed with an enlarged diameter portion  49  at a position above the annular groove  46  on the inner side surface of the upper end portion of the cap-side peripheral wall  41 . The enlarged diameter portion  49  increases an interval between the cap-side peripheral wall  41  and the body-side peripheral wall  21 . The enlarged diameter portion  49  faces the recessed groove  37  (see  FIG.  7 A ). In the embodiment, the enlarged diameter portion  49  is formed at a position above the annular groove  46  and facing the recessed groove  37  on the inner side surface of the upper end portion of the cap-side peripheral wall  41  (here, the inner side surface of a portion of the outer peripheral wall  44  above the tapered portion  47 ). More specifically, the enlarged diameter portion  49  is formed on the inner side surface of the extending portion  44   b  constituting the outer peripheral wall  44  provided on the upper end portion of the cap-side peripheral wall  41 . 
     As shown in  FIG.  1   , the cap-side peripheral wall  41  is formed with, in the upper end portion, engagement holes  50  engaged with the cap-side engagement protrusions  28  provided in the housing body  20 . In the embodiment, a plurality of elongated engagement holes  50  are formed at equal intervals in the circumferential direction in the upper end portion of the outer peripheral wall  44 . As shown in  FIG.  2   , the corresponding cap-side engagement protrusions  28  of the housing body  20  are engaged with the engagement holes  50  of the lower cap  40 , so that the lower cap  40  is installed to the lower side of the housing body  20 . As a result, the valve chamber V communicating with the inside of the fuel tank (not shown) is formed on the lower side of the housing by the partition wall  22  (see  FIG.  4   ). 
     As described above, in the fill-up restriction valve, the lower cap  40  is installed to the housing body  20  not only by the joint portion (the annular groove  46 . the insertion wall portion  33 , the annular protrusion  35 ) but also by an engagement portion (the cap-side engagement protrusions  28 , the engagement holes  50 ). That is, the lower cap  40  is installed to the housing body  20  by the joint portion and the engagement portion. 
     As shown in  FIG.  1   , the cap-side peripheral wall  41  is further formed with, in the upper end portion, positioning recesses  51  into which the positioning protrusions  30  provided on the housing body  20  are fitted. In the embodiment, the positioning recesses  51 ,  51  each having a recessed groove shape are formed by cutting out two positions of the upper end portion of the outer peripheral wall  44  that face each other in the radial direction. By fitting the positioning protrusions  30  into the positioning recesses  51 , the lower cap  40  is positioned and installed to the lower side of the housing body  20  in a rotation-restricted state. 
     As shown in  FIG.  3   , the cap-side peripheral wall  41  is further formed with, at a position below the joint portion (that is, the pressure-contact portion of the annular protrusion  35  and the inner side surface  46   a  of the annular groove  46 ), a fill-up detection opening  52  communicating the inside of the fuel tank with the inside of the valve chamber V. In the embodiment, the fill-up detection opening  52  has a substantially elongated hole shape extending by a predetermined length along the circumferential direction in the axially lower end portion of the cap-side peripheral wall  41 . The fill-up detection openings  52  are formed at two positions of the cap-side peripheral wall  41  that face each other in the radial direction. 
     The fill-up detection opening  52  communicates the inside of the fuel tank with the inside of the valve chamber V and enables continuous refueling from a refueling nozzle (not shown) in a state where the fill-up detection opening  52  is not submerged (a state where the fill-up detection opening  52  is opened without being closed by the liquid fuel). In a state where the fill-up detection opening  52  is submerged (a state where the fill-up detection opening  52  is closed by the liquid fuel), the fuel liquid level in the valve chamber V rises, the float valve  70  closes the opening  23 , and the continuous refueling from the refueling nozzle (not shown) is stopped. 
     As shown in  FIGS.  4  and  6   , the lower cap  40  further includes the spring support plate  53  that supports the biasing spring S. As shown in  FIG.  6   , the spring support plate  53  has a substantially disc shape, and is disposed on an inner side of the lower end portion of the cap-side peripheral wall  41  via a plurality of support protrusions  53   a  protruding radially inward from an inner periphery of the lower end portion of the cap-side peripheral wall  41 . 
     Between an outer periphery of the spring support plate  53  and the inner periphery of the cap-side peripheral wall  41 , a plurality of communication ports  54  are formed to communicate the inside of the fuel tank with the inside of the valve chamber V (see  FIG.  6   ). The spring support plate  53  is further provided with a spring support projection  55  projecting from a center of an upper surface thereof. The spring support projection  55  has a substantially cross-shaped projection shape and supports a base end portion of the biasing spring S. 
     As shown in  FIG.  6   , the cap-side peripheral wall  41  further includes guide ribs  56  that guide the upward and downward movement of the float valve  70 . In the embodiment, a plurality of guide ribs  56  are provided on the inner side surface of the cap-side peripheral wall  41  at equal intervals in the circumferential direction. 
     A base end portion of each guide rib  56  is located at the lower end portion of the cap-side peripheral wall  41  (more specifically, located at the support protrusion  53   a  that supports the spring support plate  53 ), and each guide rib  56  has a substantially long plate shape extending along the axial direction of the cap-side peripheral wall  41 . Among the plurality of guide ribs  56 , predetermined guide rib  56  partitions the fill-up detection opening  52  into a plurality of regions. In the embodiment, two guide ribs  56 ,  56  extend from a lower bottom surface to an upper ceiling surface of the fill-up detection opening  52 , and as shown in  FIG.  3   , when the fill-up restriction valve  10  is viewed from a lateral side, the fill-up detection opening  52  is partitioned into three regions. 
     As shown in  FIG.  6   , the cap-side peripheral wall  41  further includes a plurality of flexibly deformable strike sound suppression piece  57  extending from the inner periphery of the lower end portion thereof. Each strike sound suppression piece  57  is provided with a protrusion  57   a  protruding from a top end portion in an extending direction thereof. When the float valve  70  descends, the protrusion  57   a  abuts against a lower end surface of the float valve  70 . and the strike sound suppression piece  57  flexibly deforms (see  FIG.  4   ), thereby suppressing striking sound when the float valve  70  descends. 
     Next, the upper cover  60  installed to an upper side of the housing body  20  will be described with reference to  FIGS.  1 ,  4   , and the like. 
     The upper cover  60  has a substantial hat shape and includes a peripheral wall  61  having a substantially cylindrical outer periphery, a ceiling wall  63  disposed above the peripheral wall  61 , and a flange portion  65  extending outward from a lower side of the peripheral wall  61 . As shown in  FIG.  4   , the peripheral wall  61  is formed with a fuel vapor discharge port  67   a , and a fuel vapor discharge pipe  67  extends in the outer diameter direction from a front side peripheral edge of the fuel vapor discharge port  67   a . The fuel vapor discharge pipe  67  is connected to a tube (not shown) coupled to a canister. 
     As shown in  FIG.  1   , the flange portion  65  is provided with a plurality of engagement pieces  69  extending downward from predetermined positions thereof in the circumferential direction. Each engagement piece  69  is formed with an engagement hole  69   a . As shown in  FIG.  2   , the corresponding cover-side engagement protrusions  29  of the housing body  20  are engaged with the engagement holes  69   a  of the engagement pieces  69  of the upper cover  60 , thereby the upper cover  60  is installed to the upper side of the housing body  20  in a state where the seal ring  25  installed in the ring install groove  25   a  abuts against an inner periphery of the peripheral wall  61  of the upper cover  60  as shown in  FIG.  4   . As a result, the ventilation chamber R communicating with the outside of the fuel tank is formed on the upper side by the partition wall  22  (see  FIG.  4   ). 
     Next, the float valve  70  accommodated in the valve chamber V in a manner of being movable up and down will be described with reference to  FIGS.  1 ,  4   , and the like. 
     As shown in  FIG.  4   , the float valve  70  in the embodiment includes a float body  71  that has a circular outer periphery and generates buoyancy during immersion of fuel, and a seal member  73  that is installed above the float body  71 , moves up and down relative to the float body  71 , and comes into contact with and separates from the opening  23 . 
     Above the seal member  73 . a seal valve body  75  made of an elastic material such as rubber or elastic elastomer is installed. The seal valve body  75  is formed with a vent hole  75   a  penetrating a center thereof. The vent hole  75   a  is opened upward and downward. The seal valve body  75  comes into contact with and separates from a peripheral edge portion on a back side of the opening  23  to open and close the opening  23  (see  FIGS.  4  and  8   ), thereby the float valve  70  functions as a fill-up restriction valve. The float body  71  is formed with a spring accommodating recess  71   a  opened downward, and the biasing spring S is accommodated in the spring accommodating recess  71   a . 
     An intermediate valve body  77  is tiltably supported between the float body  71  and the seal member  73  (see  FIG.  4   ). The intermediate valve body  77  normally abuts against a lower end portion of the seal valve body  75  and closes the vent hole  75   a  (see  FIG.  4   ), and opens the vent hole  75   a  when the float body  71  descends relative to the seal member  73 . 
     In the valve chamber V. the float valve  70  is accommodated in a manner of being movable up and down in a state where the biasing spring S is interposed between the float valve  70  and the lower cap  40 , moves up by own buoyancy and a biasing force of the biasing spring S when immersed by the fuel, and moves down by own weight when not immersed by the fuel. 
     Modifications 
     Shapes and structures of the housing, the float valve constituting the present invention and shapes and structures of the housing body, the lower cap, the upper cover, the joint portion, and the like constituting the housing are not limited to the above embodiment. 
     The housing  15  in the embodiment includes the housing body  20 , the lower cap  40 , and the upper cover  60 . However, the housing may include at least the housing body and the lower cap. 
     The body-side peripheral wall  21  of the housing body  20  and the cap-side peripheral wall  41  of the lower cap  40  in the embodiment each have a substantially cylindrical shape, but may also have an elliptic cylindrical shape, a square cylindrical shape, or the like. 
     The float valve  70  in the embodiment has a multi-component configuration including the float body  71 , the seal member  73 , the intermediate valve body  77 , and the like. However, the float valve may include the seal member made of an elastic material installed above, as long as the float valve can open and close the opening  23 . 
     In the embodiment, one float valve  70  is accommodated in one valve chamber V formed inside the housing  15 . However, for example, a plurality of float valves may be accommodated in one valve chamber (functioning as a fuel cut valve, a pressure control valve, or the like in addition to a fill-up restriction valve), a plurality of valve chambers may be defined in the housing, and the float valves may be accommodated in the respective valve chambers. 
     The joint portion in the embodiment includes the annular groove  46  provided in the upper end portion of the cap-side peripheral wall  41 , the insertion wall portion  33  provided on the lower end portion of the body-side peripheral wall  21 , and the annular protrusion  35  formed on the outer side surface  33   a  on the outer diameter side of the insertion wall portion  33 , and when the insertion wall portion  33  is inserted into the annular groove  46 , the annular protrusion  35  is in pressure-contact with the inner side surface  46   a  on the outer diameter side of the annular groove  46  (see  FIG.  7 B ). However, the joint portion is not limited to this aspect. 
     For example, 
     (1) the joint portion may include the annular groove provided in the lower end portion of the body-side peripheral wall, the insertion wall portion provided on the upper end portion of the cap-side peripheral wall, and the annular protrusion formed on the outer side surface on the outer diameter side of the insertion wall portion, and in a state where the insertion wall portion is inserted into the annular groove, the annular protrusion may be in pressure-contact with the inner side surface on the outer diameter side of the annular groove and the outer side surface on the outer diameter side of the insertion wall portion,   (2) the joint portion may include the annular groove provided in the upper end portion of the cap-side peripheral wall, the insertion wall portion provided on the lower end portion of the body-side peripheral wall, and the annular protrusion formed on the outer side surface on the inner diameter side of the insertion wall portion, and in a state where the insertion wall portion is inserted into the annular groove, the annular protrusion may be in pressure-contact with the inner side surface on the inner diameter side of the annular groove and the outer side surface on the inner diameter side of the insertion wall portion,   (3) the joint portion may include the annular groove provided in the lower end portion of the body-side peripheral wall, the insertion wall portion provided on the upper end portion of the cap-side peripheral wall, and the annular protrusion formed on the outer side surface on the inner diameter side of the insertion wall portion, and in a state where the insertion wall portion is inserted into the annular groove, the annular protrusion may be in pressure-contact with the inner side surface on the inner diameter side of the annular groove and the outer side surface on the inner diameter side of the insertion wall portion,   (4) the joint portion includes the annular groove provided in the upper end portion of the cap-side peripheral wall, the insertion wall portion provided on the lower end portion of the body-side peripheral wall, and the annular protrusion formed on the inner side surface on the outer diameter side of the annular groove, and in a state where the insertion wall portion is inserted into the annular groove, the annular protrusion is in pressure-contact with the outer side surface on the outer diameter side of the insertion wall portion and the inner side surface on the outer diameter side of the annular groove,   (5) the joint portion includes the annular groove provided in the upper end portion of the cap-side peripheral wall, the insertion wall portion provided on the lower end portion of the body-side peripheral wall, and the annular protrusion formed on the inner side surface on the inner diameter side of the annular groove, and in a state where the insertion wall portion is inserted into the annular groove, the annular protrusion is in pressure-contact with the outer side surface on the inner diameter side of the insertion wall portion and the inner side surface on the inner diameter side of the annular groove.   (6) the joint portion may include the annular groove provided in the lower end portion of the body-side peripheral wall, the insertion wall portion provided on the upper end portion of the cap-side peripheral wall, and the annular protrusion formed on the inner side surface on the outer diameter side of the annular groove, and in a state where the insertion wall portion is inserted into the annular groove, the annular protrusion may be in pressure-contact with the outer side surface on the outer diameter side of the insertion wall portion and the inner side surface on the outer diameter side of the annular groove, and   (7) the joint portion may include the annular groove provided in the lower end portion of the body-side peripheral wall, the insertion wall portion provided on the upper end portion of the cap-side peripheral wall, and the annular protrusion formed on the inner side surface on the inner diameter side of the annular groove, and in a state where the insertion wall portion is inserted into the annular groove, the annular protrusion may be in pressure-contact with the outer side surface on the inner diameter side of the insertion wall portion and the inner side surface on the inner diameter side of the annular groove.   

       FIG.  9 A  shows the configuration of (1) described above. That is, in the joint portion in the modification, the annular groove  46  is provided in the lower end portion of the body-side peripheral wall  21 , the insertion wall portion  33  is provided on the upper end portion of the cap-side peripheral wall  41 , the annular protrusion  35  is formed on the outer side surface  33   a  on the outer diameter side of the insertion wall portion  33 , and in a state where the insertion wall portion  33  is inserted into the annular groove  46 , the annular protrusion  35  is in pressure-contact with the inner side surface  46   a  on the outer diameter side of the annular groove  46  and the outer side surface  33   a  on the outer diameter side of the insertion wall portion  33 . 
     The annular protrusion  35  in the embodiment has a rounded curved surface shape in cross section, and is integrally formed with the outer side surface  33   a  on the outer diameter side of the insertion wall portion  33  (see  FIG.  7 B ). Alternatively, the annular protrusion may have, for example, a trapezoidal shape in cross section, a rectangular shape in cross section, or a mountain shape having a substantially triangular shape in cross section. 
     The joint portion may be provided separately from the insertion wall portion and the annular groove, and may have an annular seal portion disposed between the insertion wall portion and the annular groove. The joint portion in the modification shown in  FIG.  9 B  includes an annular seal member  35 A separated from the insertion wall portion  33  and the annular groove  46 , and in a state where the insertion wall portion  33  is inserted into the annular groove  46 , the annular seal member  35 A is in pressure-contact with the outer side surface  33   b  on the inner diameter side of the insertion wall portion  33  and the inner side surface  46   b  on the inner diameter side of the annular groove  46 . 
     Functions and Effects 
     Next, functions and effects of the fill-up restriction valve  10  having the above-described configuration will be described. 
     Members constituting the fill-up restriction valve  10  can be assembled, for example, as follows. First, after the float valve  70  is accommodated in the valve chamber V of the housing body  20 . the biasing spring S is accommodated in the spring accommodating recess  71   a  of the float valve  70 . 
     Thereafter, the plurality of engagement holes  50  of the lower cap  40  are aligned with the corresponding cap-side engagement protrusions  28  of the housing body  20 . the annular groove  46  in the upper end portion of the cap-side peripheral wall  41  is aligned with the insertion wall portion  33  on the lower end portion of the body-side peripheral wall  21 , and the lower cap  40  is positioned to the lower side of the housing body  20 . In this state, as shown in  FIG.  7 B , the insertion wall portion  33  is disposed above the annular groove  46 . Then, as shown by an arrow in  FIG.  7 B , the housing body  20  is pressed into the lower cap  40 , or the lower cap  40  is pressed into the housing body  20 . 
     Then, the top portion of the annular protrusion  35  is pressed against the inner peripheral surface of the outer peripheral wall  44  on the upper end portion of the cap-side peripheral wall  41 , and the insertion wall portion  33  is inserted into the annular groove  46  while being slightly flexibly deformed inward in the radial direction of the valve chamber V. As shown in  FIG.  7 A , the top portion of the annular protrusion  35  is in pressure-contact with the inner side surface  46   a  on the outer diameter side of the annular groove  46 . Since the flexibly deformed insertion wall portion  33  attempts to elastically return outward in the radial direction of the valve chamber V, the annular protrusion  35  is in close pressure-contact with the inner side surface  46   a  on the outer diameter side of the annular groove  46 . At the same time, since the cap-side engagement protrusions  28  of the housing body  20  are engaged with the engagement holes  50  of the lower cap  40 , the lower cap  40  is installed to the lower side of the housing body  20  by the joint portion (the annular groove  46 , the insertion wall portion  33 , the annular protrusion  35 ) and the engagement portion (the cap-side engagement protrusions  28 , the engagement holes  50 ) (see  FIGS.  2  to  4   ). In a state where the annular protrusion  35  is in pressure-contact with the inner side surface  46   a  of the annular groove  46 , the gap G1 is defined at a position above the pressure-contact portion (see  FIG.  7 A ). 
     As described above, when the upper cover  60  is installed to the upper side of the housing body  20 , the corresponding cover-side engagement protrusions  29  of the housing body  20  are engaged with the engagement holes  69   a  of the engagement pieces  69  of the upper cover  60 , thereby the upper cover  60  is installed to the upper side of the housing body  20  as shown in  FIGS.  2  to  4   . 
     As shown in  FIG.  4   , in a state where the fuel is not sufficiently supplied into the fuel tank and the float valve  70  is not immersed in the fuel, the float valve  70  descends by own weight and the opening  23  is opened, and thus the valve chamber V communicates with the ventilation chamber R through the opening  23 . 
     When the fuel is supplied into the fuel tank in this state, air in the fuel tank mainly flows into the valve chamber V from the communication ports  54  of the lower cap  40 , passes through the gap between the float valve  70  and the cap-side peripheral wall  41  as well as the body-side peripheral wall  21  and flows upward, flows into the ventilation chamber R from the opening  23 , and is discharged to the canister outside the fuel tank. In this way, the air in the fuel tank is discharged to the outside of the fuel tank, so that the fuel can be supplied into the fuel tank. 
     When the fuel is supplied into the fuel tank from the state shown in  FIG.  4   , the fuel flows into the valve chamber V from the communication ports  54  of the lower cap  40 , and the float body  71  of the float valve  70  is immersed in the fuel. When the fuel liquid level in the fuel tank reaches a set fill-up liquid level, that is, when the fill-up detection opening  52  is closed and submerged, the float valve  70  rises due to the biasing force of the biasing spring S and the buoyancy of the float body  71  of the float valve  70 , and the seal valve body  75  abuts against the peripheral edge portion on the back side of the opening  23  and closes the opening  23 . As a result, an air flow between the valve chamber V and the ventilation chamber R through the opening  23  is blocked. Then, the fuel in the fuel tank rises through a refueling pipe provided in the fuel tank, and comes into contact with a fill-up detection sensor of a refueling nozzle inserted into a refueling port to detect the fill-up, and thus the refueling into the fuel tank is stopped and the fill-up restriction can be implemented. 
     In the fill-up restriction valve  10 , as shown in  FIGS.  4  and  7   , in a state where the insertion wall portion  33  provided on the lower end portion of the body-side peripheral wall  21  is inserted into the annular groove  46  provided in the upper end portion of the cap-side peripheral wall  41 , the annular protrusion  35  is in pressure-contact with the inner side surface  46   a  on the outer diameter side of the annular groove  46  and the outer side surface  33   a  on the outer diameter side of the insertion wall portion  33 . Accordingly, when the lower cap  40  is installed to the housing body  20  by the joint portion, the sealing performance between the housing body  20  and the lower cap  40  can be improved, and the filling-up detection accuracy can be improved. The same effect can also be obtained when the joint portion includes the annular groove provided in the lower end portion of the body-side peripheral wall, the insertion wall portion provided on the upper end portion of the cap-side peripheral wall, the annular protrusion formed on one of the outer side surface of the insertion wall portion and the inner side surface of the annular groove, or the annular seal member disposed between the insertion wall portion and the annular groove, and the annular protrusion or the seal member is in press-contract with the annular groove and the insertion wall portion in a state where the insertion wall portion is inserted into the annular groove. 
     In the embodiment, the annular groove  46  is provided in the upper end portion of the cap-side peripheral wall  41 , the insertion wall portion  33  is provided on the lower end portion of the body-side peripheral wall  21 , the annular protrusion  35  is disposed on the outer side surface  33   a  of the insertion wall portion  33 , and the gap G1 is defined at a position above the annular protrusion  35  in the state where the insertion wall portion  33  is inserted into the annular groove  46  (see  FIG.  7 A ). 
     According to the above aspect, since the gap G1 is defined at a position above the annular protrusion  35  in the state where the insertion wall portion  33  is inserted into the annular groove  46 , as shown in  FIG.  7 A , the liquid fuel can accumulate in the gap G1 by the oscillation of the fuel or the like. Since the fuel accumulating in the gap G1 can function as a so-called liquid seal (seal by liquid), the sealing performance between the housing body  20  and the lower cap  40  can be further improved. The same effect can also be obtained when the annular seal member is disposed on the outer side surface of the insertion wall portion. 
     In the embodiment, as shown in  FIG.  7 A , the body-side peripheral wall  21  is formed with the recessed groove  37  at a position above the gap G1 on the outer side surface  21   a  thereof. The recessed groove  37  communicates with the gap G1. 
     According to the above aspect, since the recessed groove  37  having the above-described configuration is provided, the liquid fuel can accumulate not only in the gap G1 but also in the recessed groove  37 . and the amount of the accumulating liquid fuel can be increased. As a result, it is easy to maintain the liquid seal function by suppressing shortage of the liquid fuel accumulating in the gap G1, and thus the sealing performance between the housing body  20  and the lower cap  40  can be improved over a long period of time. 
     In the present embodiment, as shown in  FIG.  7 A , the cap-side peripheral wall  41  is formed with the enlarged diameter portion  49  at a position above the annular groove  46  on the inner side surface of the upper end portion of the cap-side peripheral wall  41 . The enlarged diameter portion  49  increases the interval between the cap-side peripheral wall  41  and the body-side peripheral wall  21 . 
     According to the above aspect, since the enlarged diameter portion  49  having the above-described configuration is provided, the liquid fuel can accumulate in the enlarged diameter portion  49  in addition to the gap G1, and as a result, the amount of the accumulating liquid fuel can be further increased, and the liquid seal function can be more easily maintained. In addition, since the enlarged diameter portion  49  is provided, the insertion wall portion  33  is less likely to interfere with the inner side surface of the upper end portion of the cap-side peripheral wall  41  when the insertion wall portion  33  is inserted into the annular groove  46 , and thus the insertion wall portion  33  is easily inserted into the annular groove  46 . 
     In the embodiment, as shown in  FIG.  7 A , the body-side peripheral wall  21  is formed with the recessed groove  37  communicating with the gap G1 at a position above the gap G1 on the outer side surface  21   a  thereof, and the enlarged diameter portion  49  faces the recessed groove  37 . 
     According to the above aspect, since the enlarged diameter portion  49  faces the recessed groove  37 , the enlarged diameter portion  49  can be further enlarged by the recessed shape of the recessed groove  37 . As a result, the amount of the accumulating liquid fuel can be further increased, and thus the liquid seal function can be easily maintained over a long period of time. 
     In the embodiment, the cap-side peripheral wall  41  includes the fill-up detection opening  52 , which is formed at a position below the pressure-contact portion of the annular protrusion  35  and the inner side surface  46   a  of the annular groove  46  and communicates the inside of the fuel tank with the inside of the valve chamber V, and the guide ribs  56  that guide the upward and downward movement of the float valve  70 , and the plurality of guide ribs  56  are disposed on the inner periphery of the cap-side peripheral wall  41  to partition the fill-up detection opening  52  into a plurality of regions (see  FIGS.  3  and  6   ). 
     According to the above aspect, the guide ribs  56  are disposed on the inner periphery of the cap-side peripheral wall  41  to partition the fill-up detection opening  52  into a plurality of regions. Accordingly, when gas such as air or fuel vapor is about to flow into the valve chamber V from the fill-up detection opening  52  at the time of refueling to the fuel tank or at the time of an increase in pressure in the fuel tank, the plurality of guide ribs  56  can make it less likely for the gas to flow into the valve chamber V, and the float valve  70  can be suppressed from blowing up. As a result, the float valve  70  can be suppressed from rising and closing the opening  23  at a pressure lower than a set valve closing pressure. 
     Other Embodiments of Fill-Up Restriction Valve 
       FIGS.  10  and  11    show another embodiment of a fill-up restriction valve according to the present invention. Substantially the same portions as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted. 
     In a fill-up restriction valve  10 A in the embodiment, the housing  15  includes the upper cover  60 , and a first engagement piece extends downward from the upper cover  60 . In the embodiment, each of the engagement pieces  69  serves as a “first engagement piece” in the present invention. The engagement pieces  69  are engaged with the cover-side engagement protrusions  29  (serving as a “first engagement protrusion” in the present invention, respectively) provided on the housing body  20 . 
     A second engagement piece is formed on the lower cap  40 . In the embodiment, the upper end portion of the outer peripheral wall  44  of the cap-side peripheral wall  41  is separated by the plurality of positioning recesses  51  to form second engagement pieces  44   c . Each of the second engagement pieces  44   c  is formed with the engagement hole  50 . The second engagement pieces  44   c  are engaged with the cap-side engagement protrusions  28  (serving as a “second engagement protrusion” in the present invention, respectively) provided on the housing body  20 , and are disposed outside the engagement pieces  69  serving as the first engagement pieces. Each second engagement piece  44   c  is provided with a pair of protrusions  44   e ,  44   e  protruding on an outer peripheral surface of an upper side portion  44   d  thereof, and the rigidity of the upper side portion  44   d  of the second engagement piece  44   c  is improved. 
     As described above, in the fill-up restriction valve  10 A in the embodiment, the housing  15  further includes the upper cover  60  installed to the upper side of the housing body  20 , and the first engagement pieces (the engagement pieces  69 ) is formed on the upper cover  60 . The second engagement pieces  44   c  are formed on the lower cap  40 . The housing body  20  is provided with the first engagement protrusions (the cover-side engagement protrusions  29 ) engaged with the engagement pieces  69  that are the first engagement pieces and the second engagement protrusions (the cap-side engagement protrusions  28 ) engaged with the second engagement pieces  44   c . As shown in  FIGS.  10  and  11   , the second engagement pieces  44   c  engage with the cap-side engagement protrusions  28  that are the second engagement protrusions in a state where the second engagement pieces  44   c  are disposed outside the engagement pieces  69  that are the first engagement pieces. 
     The fill-up restriction valve  10 A having the above configuration has the following effects. 
     That is, when the lower cap  40  and the upper cover  60  are installed to the lower side and the upper side of the housing body  20 , the first engagement protrusions (the cover-side engagement protrusions  29 ) of the housing body  20  are engaged with the first engagement pieces (the engagement pieces  69 ) of the upper cover  60 , and the second engagement protrusions (the cap-side engagement protrusions  28 ) of the housing body  20  are engaged with the second engagement pieces  44   c  of the lower cap  40 . 
     At this time, as shown in  FIGS.  10  and  11   , the second engagement pieces  44   c  of the lower cap  40  are engaged with the second engagement protrusions (cap-side engagement protrusions  28 ) of the housing body  20  in a state where the second engagement pieces  44   c  are disposed outside the first engagement pieces (the engagement pieces  69 ) of the upper cover  60 . Therefore, the outward deformation of the engagement pieces  69  that are the first engagement pieces can be suppressed by the second engagement pieces  44   c . As a result, the engagement pieces  69  that are the first engagement pieces can be suppressed from being disengaged from the cover-side engagement protrusions  29  that are the first engagement protrusions, and the install strength between the housing body  20  and the upper cover  60  can be improved. 
     The present invention is not limited to the embodiments described above, various modifications can be made within the gist of the present invention, and such modifications are also included in the scope of the present invention.