JP2013099991A - Valve device for fuel tank and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve device for a resin-made fuel tank capable of suppressing swelling by fuel and a method for producing the same.SOLUTION: The valve device 1 for the fuel tank has a cylindrical casing 6 attached to an opening 4 formed in an upper wall 3 of the fuel tank 2 and having a passage 20 communicating the inside and the outside of the fuel tank and a valve seat 16 arranged in the passage, and a float 7 supported displaceably in a vertical direction in the passage of the casing, moving up and down receiving buoyancy from fuel flowing into the passage, and sitting on the valve seat and closing the passage when moving upward and is characterized in that the float is formed of a single crystalline thermoplastic resin and has a cylindrical part 22 having an outer peripheral face part 33, an inner peripheral face part 34 and an intermediate part 35 between the outer peripheral face part and the inner peripheral face part in a radial direction, and each of the outer peripheral face part and the inner peripheral face part contains a crystal part of the crystalline thermoplastic resin oriented in a radial direction more than the intermediate part.

Description

  The present invention relates to a fuel tank valve device used in a fuel tank of an automobile and a method for manufacturing the same. The fuel tank valve device opens and closes according to the fuel level, opens when the liquid level is low, and releases the vapor in the fuel tank to the outside, while closing when the liquid level is high Block distribution.

  2. Description of the Related Art Conventionally, in a fuel tank of an automobile, there is one in which a fuel tank valve device is provided in an opening formed in an upper wall in order to suppress an increase in internal pressure (for example, Patent Document 1). The fuel tank valve device according to Patent Literature 1 includes a casing that is attached to an opening and defines a passage, and a float that is movably supported in the casing. The casing has a passage extending in the vertical direction so as to communicate the inside and the outside of the fuel tank, and has a valve seat in the middle of the passage. A float is supported at the lower part of the passage so as to be movable up and down. When the level of fuel (gasoline, light oil, etc.) in the fuel tank is low, the float is spaced from the valve seat and opens the passage. Therefore, the vapor in the fuel tank can pass through the passage and flow out to the outside. On the other hand, when the liquid level of the fuel becomes high and the fuel enters the passage, the float receives buoyancy in the fuel and moves upward, sits on the valve seat and closes the passage. This prevents the fuel from flowing out.

Japanese Patent Laid-Open No. 10-71861

  The casing and float of the fuel tank valve device as described above may be made of resin, but the resin casing and float are immersed in an organic solvent containing petroleum fuel such as gasoline or light oil. There is a problem of swelling. Swelling refers to a phenomenon in which an organic solvent (fuel) permeates between polymer chains of a solidified resin and the volume expands. When the casing or the float swells, the float and the inner surface of the passage come into contact with each other and interfere with each other, and the opening and closing of the passage according to the liquid level is hindered.

  This invention is made | formed in view of the above background, Comprising: It aims at providing the valve apparatus for resin fuel tanks which can suppress the swelling by a fuel, and its manufacturing method.

  In order to solve the above problems, the present invention provides a fuel tank valve device (1), which is attached to an opening (4) formed in an upper wall (3) of a fuel tank (2), And a cylindrical casing (6) having a passage (20) communicating between the inside and the outside of the casing and a valve seat (16) provided in the passage, and supported in the passage of the casing so as to be vertically displaceable. A float (7) that receives buoyancy from the fuel flowing into the passage and moves up and down and closes the passage when the valve seat moves upward. A cylindrical portion (22) which is molded from a crystalline thermoplastic resin and has an outer peripheral surface portion (33), an inner peripheral surface portion (34) and an intermediate portion (35) between the outer peripheral surface portion and the inner peripheral surface portion in the radial direction. Each of the outer peripheral surface portion and the inner peripheral surface portion. Is characterized in that the crystal portion of the crystalline thermoplastic resin is oriented in the radial direction comprises more than the intermediate portion. Here, the crystalline thermoplastic resin is polyethylene (PE), polypropylene (PP), polyamide (PA), polyacetal (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), It refers to a thermoplastic resin having a crystal part in which polymer chains are regularly arranged when solidified, such as polyetheretherketone (PEEK) or polytetrafluoroethylene (PTFE). In addition, the fuel refers to a petroleum-based fuel such as light oil or gasoline, or a fuel mainly composed of hydrocarbons including ethanol.

  According to this configuration, the outer peripheral surface portion and the inner peripheral surface portion of the cylindrical portion of the float include many cylindrically-oriented crystal parts oriented in the radial direction. Therefore, fuel (organic solvent such as gasoline and light oil) is formed in the gap between the polymer chains. ) Is difficult to enter, and swelling is suppressed.

  Another aspect of the present invention is a method for producing a float (7) having a cylindrical resin molded body that moves up and down by receiving buoyancy from fuel in a casing (6) of a valve device (1) for a fuel tank. Preparing a mold (40) having a cylindrical cavity (50) and a movable member (43) for reducing the cavity from the axial direction, and melting the crystalline thermoplastic resin into the cavity A step of filling, displacing the movable member, pressurizing the crystalline thermoplastic resin filling the cavity from the axial direction, and each of the crystal portions of the outer peripheral surface portion and the inner peripheral surface portion in the radial direction And a step of solidifying the crystalline thermoplastic resin while maintaining pressure.

  According to this configuration, the outer peripheral surface portion and the inner peripheral surface portion of the cylindrical portion of the float can include many crystal parts oriented in the radial direction.

  Another aspect of the present invention further includes a step of leaving the cavity for a predetermined compression start delay time after the step of filling the melted crystalline thermoplastic resin into the cavity, and then displacing the movable member. The method further comprises a step of pressurizing the crystalline thermoplastic resin filled in the cavity from the axial direction.

  According to this configuration, before the pressurization by the movable member is started, the resin near the cavity surface can be further cooled, and when the pressurization by the movable member is performed, the outer peripheral surface portion and the inner peripheral surface portion. It is possible to reliably orient the crystal part in the radial direction.

  Another aspect of the present invention is a resin molded body (7) having a cylindrical portion (22) used under conditions immersed in an organic solvent, which is molded from a single crystalline thermoplastic resin, In the radial direction of the cylindrical portion, the cylindrical portion has an outer peripheral surface portion (33), an inner peripheral surface portion (34), and an intermediate portion (35) between the outer peripheral surface portion and the inner peripheral surface portion, Each of the inner peripheral surface portions includes a larger number of crystal parts of the crystalline thermoplastic resin oriented in the radial direction than the intermediate part. Here, the organic solvent means a petroleum-based fuel such as gasoline or light oil, or a hydrocarbon-based solvent containing alcohol or the like.

  According to this configuration, since the outer peripheral surface portion and the inner peripheral surface portion of the cylindrical portion of the resin molded body contain many crystal parts oriented in the radial direction of the cylindrical portion, it is difficult for the organic solvent to enter the gaps between the polymer chains. Swelling is suppressed.

  According to the above configuration, it is possible to provide a resin fuel tank valve device that can suppress swelling due to fuel (organic solvent).

Cross section of fuel tank valve device Perspective view of float of fuel tank valve device Schematic sectional view showing the cylindrical part of the float Cross section of float mold Diagram showing float forming process Diagram showing float forming process Graph showing the results of X-ray diffraction analysis of the outer peripheral surface part and the intermediate part of the float

  Hereinafter, an embodiment in which the present invention is applied to a valve device provided in a fuel tank of an automobile will be described with reference to the drawings.

  As shown in FIG. 1, the valve device 1 is attached to an attachment hole 4 that is a through hole formed in an upper wall 3 of a fuel tank 2 of an automobile. The fuel tank 2 is made of a resin such as high-density polyethylene or a metal, for example.

  The valve device 1 includes a casing 6 and a float 7 supported by the casing 6. The casing 6 is configured by combining a first casing 8 and a second casing 9. The first casing 8 and the second casing 9 are made of a resin material. The resin material is preferably a thermoplastic resin, and more preferably a crystalline thermoplastic resin. In the present embodiment, the first casing 8 and the second casing 9 are made of polyacetal.

  The first casing 8 has a cylindrical portion 12 whose one end is closed by an end plate 11 and whose other end is open. A flange 13 extending outward in the radial direction is formed at the end of the cylindrical portion 12 on the end plate 11 side. At the center of the end plate 11, a connecting pipe 14 is provided so as to extend along the axis of the cylindrical portion 12 to a side different from the cylindrical portion 12 side. The connecting pipe 14 is bent at a substantially right angle at an intermediate portion in the longitudinal direction and has an L shape. A pipe line 15 formed inside the connection pipe 14 passes through the end plate 11 and communicates with the inside of the cylindrical portion 12. A pipe line 15 is opened at a central portion of the surface of the end plate 11 facing the cylindrical portion 12, and the opening end is enlarged in a taper shape to form a valve seat 16.

  The second casing 9 has a cylindrical shape with a bottom plate 17 at one end and an opening at the other end. A passage hole 18, which is a through hole, is formed at the center of the bottom plate 17. The second casing 9 is attached to the first casing 8 by fitting the open end of the cylindrical portion 12 into the second casing 9. The second casing 9 and the cylindrical portion 12 may be further joined by welding or the like. With the second casing 9 attached to the first casing 8, the bottom plate 17 covers the open end of the cylindrical portion 12, and the float receiving portion 19 is defined inside the cylindrical portion 12. The casing 6 including the first casing 8 and the second casing 9 has a passage 20 including a passage hole 18, a float receiving portion 19, and a pipe line 15.

  As shown in FIGS. 1 and 2, the float 7 includes a cylindrical portion 22 extending along the axis A and an end plate 23 that closes one end of the cylindrical portion 22. The other end of the cylindrical portion 22 is open. A conical valve body 24 that protrudes from the central portion of the outer surface side of the end plate 23 so as to be seated on the valve seat 16 and close the pipe line 15 is provided. A plurality of communication holes 25 penetrating the end plate 23 are formed at appropriate positions of the end plate 23. The float 7 is formed from a crystalline thermoplastic resin, and in this embodiment is formed from polyacetal.

  As shown in FIG. 3, in the radial direction of the cylindrical portion 22, the surface layer portion including the outer peripheral surface 31 is the outer peripheral surface portion 33, the surface layer portion including the inner peripheral surface 32 is the inner peripheral surface portion 34, and the outer peripheral surface portion 33 and the inner peripheral surface portion 34. A portion sandwiched between the intermediate portions 35 is referred to as an intermediate portion 35. In addition, the boundary of the outer peripheral surface part 33, the intermediate | middle part 35, and the inner peripheral surface part 34 does not appear clearly, but the material is the same and the internal structure changes gradually. The outer peripheral surface portion 33 and the inner peripheral surface portion 34 include many crystal parts oriented in the radial direction of the cylindrical portion 22. The ratio of the crystal part in which the outer peripheral surface part 33 and the inner peripheral surface part 34 are oriented in the radial direction of the cylindrical part 22 included per unit volume is larger than that of the intermediate part 35.

  The float 7 is received by the float receiving portion 19 in a posture in which the axis A of the cylindrical portion 22 is substantially parallel to the axis of the cylindrical portion 12 of the first casing 8 and the valve body 24 faces the valve seat 16. The float 7 can be moved (displaced) in the axial direction of the cylindrical portion 12 while being received in the float receiving portion 19, and the valve body 24 is seated on the valve seat 16 and the conduit 15 (passage 20). And a position where the valve body 24 leaves the valve seat 16 and opens the pipe line 15 (passage 20).

  The valve device 1 is attached to the fuel tank 2 such that the cylindrical portion 12 of the first casing 8 is inserted into the attachment hole 4 of the fuel tank 2 and the flange 13 is in contact with the outer surface of the upper wall 3. As a result, the mounting hole 4 is blocked by the casing 6, and the inside and outside of the fuel tank 2 are communicated via the passage 20 of the casing 6. The flange 13 is welded to the peripheral edge portion of the mounting hole 4 of the upper wall 3. In other embodiments, the bonding between the flange 13 and the upper wall 3 may utilize an adhesive. Moreover, you may make it form a male screw or a female screw in the flange 13 and the upper wall 3, and screw them together. In a state where the valve device 1 is attached to the fuel tank 2, the axes of the cylindrical portion 12 and the cylindrical portion 22 extend substantially in the vertical direction, and the float 7 can move up and down in the float receiving portion 19. The outer end of the connection pipe 14 is connected to a connection hose 27 connected to a canister (not shown).

  Operation | movement of the valve apparatus 1 comprised as mentioned above is demonstrated. When the gasoline level in the fuel tank 2 is low and the gasoline does not reach the casing 6, the float 7 is supported on the bottom plate 17 of the casing 6. That is, the float 7 is positioned below in the float receiving portion 19, and the valve body 24 is separated from the valve seat 16. In this state, the pipe line 15 (passage 20) is opened, and the gasoline vapor in the fuel tank 2 passes through the passage hole 18, the inside of the cylindrical portion 22 of the float 7, the communication hole 25, the float receiving part 19, and the pipe. It can flow through the path 15 to the connection hose 27. That is, gasoline vapor can flow from the inside of the fuel tank 2 to the connection hose 27 through the passage 20.

  When the liquid level of gasoline in the fuel tank 2 becomes high and the gasoline passes through the passage 20 and enters the float receiving portion 19, the float 7 receives buoyancy from the gasoline according to the liquid level of the gasoline, and the float It moves upward in the receiving part 19. When the gasoline level reaches a predetermined height, the valve body 24 is seated on the valve seat 16 and the conduit 15 (passage 20) is closed. As a result, gasoline liquid and vapor are prevented from passing through the passage 20 and from the fuel tank 2 through the passage 20 to the connection hose 27.

  When the specific gravity of the float 7 is larger than that of gasoline, a compression coil spring may be interposed between the bottom plate 17 and the end plate 23 to assist the upward movement of the float 7.

  Since the float 7 includes many crystal parts oriented in the radial direction of the cylindrical part 22 in the outer peripheral surface part 33 and the inner peripheral surface part 34, it is difficult for gasoline to enter the polymer chain of the cylindrical part 22. Therefore, the swelling rate in the radial direction of the cylindrical portion 22 can be lowered. Here, the swelling ratio in the radial direction of the cylindrical portion 22 refers to the ratio of the cylindrical portion 22 expanding in the radial direction by immersion in gasoline, and from the outer diameter of the cylindrical portion 22 after immersion to the cylindrical portion 22 before immersion. A value (%) obtained by dividing the value obtained by subtracting the outer diameter by the outer diameter of the cylindrical portion 22 before immersion.

  Next, a method for manufacturing the float 7 will be described. The float 7 is molded using an injection compression molding method. FIG. 4 shows a mold 40 used for forming the float 7. The mold 40 includes a first mold 41, a second mold 42, and a movable member 43 incorporated in the second mold 42.

  The first molding die 41 has an outer peripheral surface 31 (see FIGS. 1 and 2) of the cylindrical portion 22 of the float 7, an outer surface of the end plate 23, and a concave portion 44 corresponding to the valve body 24. The recess 44 has an axis B corresponding to the axis A of the float 7. A resin supply path 45 (including a gate, a runner, and a sprue) for supplying resin is formed at the bottom of the recess 44. Although not shown, a shape corresponding to the communication hole 25 of the float 7 is formed at the bottom of the recess 44.

  The second molding die 42 enters the concave portion 44 of the first molding die 41 and has a columnar convex portion 47 corresponding to the inner peripheral surface 32 (see FIG. 1) of the cylindrical portion 22 of the float 7 and the inner surface of the end plate 23. have. The convex portion 47 is coaxial with the axis B. The second mold 42 is preferably formed of a metal having high thermal conductivity, such as beryllium copper alloy, for example, in order to enhance the cooling effect of the resin to be molded. In another embodiment, a cooling pipe may be provided inside the convex portion 47 in order to enhance the cooling effect.

  The second mold 42 is provided with an annular movable member 43 at a portion corresponding to the open end surface of the cylindrical portion 22 of the float 7. The movable member 43 is provided with an arm portion 49 that extends through the second molding die 42 and extends in parallel with the axis B. By pressing the arm portion 49, the movable member 43 is axially aligned with respect to the second molding die 42. It can be displaced in the B direction. Thereby, the movable member 43 can be displaced in the direction of the axis A of the cylindrical portion 22 of the float 7 to be molded.

  By combining the first mold 41 and the second mold 42 to which the movable member 43 is attached, the cavity 50 corresponding to the shape of the float 7 is formed by the first mold 41, the second mold 42 and the movable member 43. Is defined. A portion of the cavity 50 corresponding to the opening end of the cylindrical portion 22 is reduced in the axis B direction by the displacement of the movable member 43.

  When molding the float 7, first, the first molding die 41 and the second molding die 42 to which the movable member 43 is attached are combined to form the cavity 50. As shown in FIG. The melted crystalline thermoplastic resin is filled into the cavity 50 through the supply path 45. The filling of the resin is performed using an injection device (not shown). When the filling of the resin is completed, the resin supply path 45 is closed and the reverse flow of the resin is prohibited.

  Next, after the resin filling is completed, the compression start delay time is left for 15 seconds or less, and then the arm portion 49 is pressed as shown in FIG. 6 to displace the movable member 43 in the axis B direction. The compression may be started during the injection (filling) of the resin. Thereby, the resin filled in the cavity 50 is pressurized (compressed) in the direction of the axis B. The pressure of the resin at this time is 60 MPa or more, and the portion corresponding to the cylindrical portion 22 is compressed by 3% or more in the axis B direction.

  Next, the resin is allowed to cool for 15 to 85 seconds while the position of the movable member 43 is maintained, that is, the pressure of the resin by the movable member 43 is maintained, and the resin is solidified. After the resin is solidified, the pressure applied by the movable member 43 is stopped, the solidified resin is taken out from the first mold 41 and the second mold 42, and the portion corresponding to the resin supply path 45 is removed. Thereby, the float 7 is completed.

  The cylindrical part 22 of the float 7 formed as described above includes more crystal parts oriented in the radial direction of the cylindrical part 22 than the intermediate part 35 in the outer peripheral surface part 33 and the inner peripheral surface part 34. This is because the resin after filling the cavity 50 is pressurized from the axial direction of the cylindrical portion 22. Since the resin filled in the cavity 50 is cooled from the portion in contact with the surface of the cavity 50, the outer peripheral surface portion 33 and the inner peripheral surface portion 34 of the cylindrical portion 22 have a lower temperature than the intermediate portion 35 and are crystallized. And solidification begins. In this state, when pressure is applied from the axis A direction of the cylindrical portion 22, the outer peripheral surface portion 33 and the inner peripheral surface portion 34 try to escape in a direction along a virtual plane orthogonal to the axis A direction. At this time, since the intermediate portion 35 has a higher temperature and lower viscosity than the outer peripheral surface portion 33 and the inner peripheral surface portion 34, the outer peripheral surface portion 33 and the inner peripheral surface portion 34 are in the direction in which the intermediate portion 35 exists, that is, the diameter of the cylindrical portion 22. The polymer chain runs in the radial direction, and the crystal part is oriented in the radial direction. By filling the cavity 50 with the resin and leaving it for the compression start delay time, the temperature difference between the outer peripheral surface portion 33 and the inner peripheral surface portion 34 and the intermediate portion 35 becomes larger, so the viscosity difference becomes larger, The outer peripheral surface portion 33 and the inner peripheral surface portion 34 include more crystal parts oriented in the radial direction of the cylindrical portion 22. Since the outer peripheral surface portion 33 and the inner peripheral surface portion 34 including the oriented crystal portion are cooled and solidified in a pressurized state, the oriented crystal structure is maintained even after the solidification is completed. On the other hand, the intermediate portion 35 is higher in temperature and lower in viscosity than the outer peripheral surface portion 33 and the inner peripheral surface portion 34 when pressed, so that the crystal portion is not oriented in one direction, and in a random direction. Orient.

  Further, the pressure of the resin by the movable member 43 reduces voids and sink marks in the molded float 7. Further, if the resin is solidified while the resin is pressed by the movable member 43, sink does not occur, so that the resin adheres to the surface of the cavity 50, and the outer peripheral surface portion 33 and the inner peripheral surface portion 34 are more efficiently cooled. Done. Thereby, since the temperature gradient becomes larger between the outer peripheral surface portion 33 and the inner peripheral surface portion 34 and the intermediate portion 35, the outer peripheral surface portion 33 and the inner peripheral surface portion 34 have crystal parts oriented in the radial direction of the cylindrical portion 22. More will be included. Further, the molding time (cooling time) can be shortened by improving the cooling effect. In addition, the thickness of the cylindrical portion 22 in the radial direction is uniform.

  Examples of the float 7 according to the above embodiment will be described below. In the examples, the resin was a polyacetal resin (POM 98% or more, stabilizer, etc. 2% or less). The molding conditions in the examples are the above-described molding die 40, the resin temperature of 200 ° C., the temperature of the first molding die 41 of 45 ° C., the injection pressure of 100 MPa, the injection time of 8 seconds, and the compression start delay time. The holding pressure after compression was 60 MPa, the compression amount (compression length in the direction of the axis B) was 3%, and the cooling time in the pressurized state was 60 seconds. In the comparative example, pressure (compression) by the movable member 43 was not performed, the holding pressure was 100 MPa, and the cooling time was 60 seconds. Other conditions in the comparative example are the same as those in the example.

  As mentioned above, it shows about the result of the produced Example and a comparative example. FIG. 7 is a diagram showing the results of X-ray crystal structure analysis of the outer peripheral surface portion 33 and the intermediate portion 35 of the example. X-ray crystal structure analysis uses an X-ray analyzer D8 Discovery with GADDS (BRUKER), and by transmission method, X-ray wavelength 1.542 mm (CuK α), X-ray tube current 110 mA, X-ray tube voltage 45 kV, Measurement was performed with a collimator diameter of φ500 μm. As shown in FIG. 7, the specific peak is not confirmed in the graph 100 showing the result of the intermediate portion 35. This indicates that the crystal part included in the intermediate part 35 does not have a specific orientation. On the other hand, in the graph 101 showing the result of the outer peripheral surface portion 33, a peak appears at −100 to −100 degrees. This indicates that the crystal part included in the outer peripheral surface part 33 is oriented in the radial direction of the cylindrical part 22.

  Next, the gasoline immersion test of the float 7 which concerns on an Example and a comparative example was done. The test is performed by immersing the float 7 according to the example and the comparative example in 60 ° C. gasoline for 168 hours, and the dimensions of the float 7 before and after the immersion (the axial length and the outer diameter of the cylindrical portion 22). Measured and confirmed swelling rate. The swelling ratio is a value (%) obtained by dividing the dimension before immersion from the dimension after immersion by the dimension before immersion, and the two directions of the axial direction of the cylindrical portion 22 and the radial direction of the cylindrical portion 22. Confirmed in As a result, it was confirmed that there is no difference in the swelling ratio in the axial direction of the cylindrical portion 22 in the float 7 according to the example and the comparative example. On the other hand, the swelling rate in the radial direction of the cylindrical portion 22 of the float 7 according to the example is 0.60%, and the swelling rate in the radial direction of the cylindrical portion 22 of the float 7 according to the comparative example is 1.40%. Was confirmed. That is, it was confirmed that the swelling rate in the radial direction of the cylindrical portion 22 is less than half that of the float 7 according to the example.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, the shape of the float 7 is an example, and other various shapes can be applied. In another embodiment, the molding method of the float 7 according to the embodiment may be applied to the molding of the first casing 8 and the second casing 9.

  DESCRIPTION OF SYMBOLS 1 ... Valve apparatus, 2 ... Fuel tank, 3 ... Upper wall, 4 ... Mounting hole, 6 ... Casing, 7 ... Float, 8 ... 1st casing, 9 ... 2nd casing, 15 ... Pipe line, 16 ... Valve seat, DESCRIPTION OF SYMBOLS 18 ... Passage hole, 19 ... Float receiving part, 20 ... Passage, 22 ... Cylindrical part, 4 ... Valve body, 25 ... Communication hole, 31 ... Outer peripheral surface, 32 ... Inner peripheral surface, 33 ... Outer peripheral surface part, 34 ... Inner peripheral Surface portion, 35 ... intermediate portion, 40 ... molding die, 41 ... first molding die, 42 ... second molding die, 43 ... movable member, 44 ... concave, 45 ... resin supply path, 47 ... convex portion, 49 ... arm portion , 50 ... cavity

Claims (4)

A fuel tank valve device,
A cylindrical casing attached to an opening formed in the upper wall of the fuel tank, having a passage communicating the inside and outside of the fuel tank and a valve seat provided in the passage;
The casing is supported so as to be vertically displaceable in the passage, and moves up and down by receiving buoyancy from the fuel flowing into the passage. When the casing moves upward, the seat sits on the valve seat and closes the passage. With a float,
The float is molded from a single crystalline thermoplastic resin, and has a cylindrical portion having an outer peripheral surface portion, an inner peripheral surface portion, and an intermediate portion between the outer peripheral surface portion and the inner peripheral surface portion in the radial direction,
Each of the said outer peripheral surface part and the said inner peripheral surface part contains the crystal | crystallization part of the said crystalline thermoplastic resin oriented in the said radial direction more than the said intermediate part, The fuel tank valve apparatus characterized by the above-mentioned. In the casing of the fuel tank valve device, a method for producing a float having a cylindrical resin molded body that moves up and down by receiving buoyancy from fuel,
Preparing a mold having a cylindrical cavity and a movable member for reducing the cavity from the axial direction;
Filling the cavity with the molten crystalline thermoplastic resin;
Displacing the movable member, pressurizing the crystalline thermoplastic resin filled in the cavity from the axial direction, and orienting the crystal portions of the outer peripheral surface portion and the inner peripheral surface portion in the radial direction; ,
And a step of solidifying the crystalline thermoplastic resin while maintaining the pressure.   After the step of filling the melted crystalline thermoplastic resin into the cavity, the method further includes a step of leaving the cavity for a predetermined compression start delay time, and then displacing the movable member to fill the cavity with the crystal The method for producing a float according to claim 2, further comprising a step of pressurizing the thermoplastic resin from the axial direction. A resin molded body having a cylindrical portion used under conditions immersed in an organic solvent,
Molded from a single crystalline thermoplastic resin,
In the radial direction of the cylindrical portion, it has an outer peripheral surface portion, an inner peripheral surface portion, and an intermediate portion between the outer peripheral surface portion and the inner peripheral surface portion,
Each of the outer peripheral surface portion and the inner peripheral surface portion includes a crystal part of the crystalline thermoplastic resin oriented in the radial direction more than the intermediate part.

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