JP4712981B2 - Plastic vent valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a synthetic resin vent valve, and more particularly to a synthetic resin vent valve that is joined to an opening of a synthetic resin tank by heat welding.
[0002]
[Prior art]
Since rust prevention and weight reduction are easy and high productivity can be obtained, the momentum of using a fuel tank by blow molding of a synthetic resin material is increasing recently. Such a synthetic resin fuel tank is provided with accessory parts such as a filler neck and a vent valve, and the connecting portion with the tank is preferably formed of a material that can be heat-welded.
[0003]
By the way, high-density polyethylene (hereinafter referred to as HDPE) capable of heat welding has a low impermeability (hereinafter referred to as barrier property) of hydrocarbons (hereinafter referred to as HC). Not suitable for use in gasoline tank accessories.
[0004]
In order to suppress the permeation of HC, it is preferable to use a material having a high barrier property such as an ethylene vinyl alcohol copolymer (hereinafter referred to as EVOH), but such a so-called gasoline barrier material has an adhesive property by heat welding. Since it is low, if the accessory part is formed of a gasoline barrier material, it is difficult to satisfy the bonding strength between the tank body and the accessory part.
[0005]
In order to cope with such inconvenience, a tank body is formed of a laminated material obtained by sandwiching a film-like gasoline barrier material with a heat-weldable material, an accessory part is formed of the gasoline barrier material, and the heat-welding is performed. A structure has been proposed in which only the part is molded in two colors with a heat-weldable material.
[0006]
[Problems to be solved by the invention]
By the way, it is necessary to provide a hose connection port in the vent valve, and in order to simplify the overall structure, it is preferable that the hose connection port is integrally formed with a flange portion which is a heat welding portion by a two-color molding method. However, it is difficult to sufficiently satisfy the relatively high strength required for the hose connection port with the weldable material.
[0007]
Moreover, since it will become unsightly if a molten resin flows out outside at the time of pressurization at a welding part, it is good to provide the recessed part for making molten resin flow in on the inner peripheral side of a flange. However, when the flange portion made of a heat-weldable material is formed at the upper end of the valve body by two-color molding, it is necessary to insert an intermediate mold for forming a recess, but the intermediate mold obtains a predetermined accuracy. For this purpose, high rigidity is required, and clearance from the valve main body is necessary for the convenience of die cutting, and it has been difficult to form an annular recess at the base of the flange by two-color molding.
[0008]
The present invention has been devised in order to solve such problems of the prior art, and the main purpose thereof is a synthetic resin configured to achieve both high heat weldability and strength. The object is to provide a vent valve.
[0009]
In order to achieve such an object, the synthetic resin vent valve according to the present invention is primarily molded from a resin material having a strength higher than that of a resin material having heat weldability, and a cylindrical case constituting the valve main body, and heat welding. A head part that is secondarily molded at the upper end of the cylindrical case by a resin material having a property, a vertical part that protrudes from the center part of the head part, and a horizontal part that extends from the upper end of the vertical part A hose connection port by secondary molding made of a resin material having a heat-welding property that forms an elbow shape, and formed on the outer periphery of the head portion, and has a heat-welding property radially outward for heat-welding to another part and a flange portion by secondary molding for attachment made of a resin material, the hose connecting port of the strut to be inserted in the vertical portion is integrally formed on the cylindrical case, the upper end of said post, before A step is provided that lowers the side from which the horizontal portion extends, and the step does not extend from the extended side of the horizontal portion at the connecting portion between the vertical portion and the horizontal portion of the hose connection port. The volume of the resin material flowing into the side is equalized.
[0010]
If it does in this way, the bending rigidity of the especially vertical part of a hose connection mouth will be raised with a support.
[0011]
In particular, by providing a step (18) having a lower side on which the horizontal portion is extended at the upper end of the column, the volume balance of the elbow-shaped portion when the column is inserted can be equalized.
[0012]
Further, in the synthetic resin vent valve according to the present invention, an annular covering portion that covers the outer peripheral surface of the upper end portion of the cylindrical case is provided at the base of the lower surface side of the flange portion.
[0013]
In this way, the thickness dimension of the intermediate mold (13) can be increased by the amount corresponding to the annular covering portion.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0015]
FIG. 1 is a longitudinal sectional view of a vent valve constructed according to the present invention. In FIG. 1, the vent valve 1 includes a float body 2 and a valve main body portion 4 formed of a cylindrical case 3 incorporating the same, a head portion 5 formed at the upper end of the cylindrical case 3, and the center of the head portion 5. An elbow-shaped hose connection port 8 comprising a vertical portion 6 projecting from the portion and a horizontal portion 7 extending from the upper end of the vertical portion 6, and a radially outward direction formed on the outer periphery of the head portion 5 The flange portion 9, the head portion 5, the hose connection port 8, and the gasoline barrier portion 10 formed on the surface layer of the flange portion 9.
[0016]
The vent valve 1 is formed by first molding the cylindrical case 3 with a relatively strong material such as polyacetal, and then inserting the cylindrical case 3 into another mold (see FIG. 2). The molten HDPE is injected into the cavity C, and the head portion 5, the hose connection port 8 and the flange portion 9 are secondarily molded. Further, the head portion 5, the hose connection port 8 and the flange portion 9 are formed in another mold. The gasoline barrier part 10 made of EVOH is inserted into the inside and is obtained by tertiary molding.
[0017]
As shown in FIG. 2, an annular convex portion 13 is provided on the inner periphery between the upper mold 11 and the lower mold 12 that are divided on the plane through which the axis of the cylindrical case 3 passes during the secondary molding. By sandwiching the intermediate mold 14, an annular recess 15 is formed at the base of the lower surface side of the flange portion 9 for allowing the molten resin to flow during heat welding.
[0018]
The upper mold 11 and the lower mold 12 can be opened and closed in the left-right direction or the front-rear direction in FIG. Then, after the lower mold 12 is opened, the intermediate mold 14 is moved downward in the axial direction so as to be extracted from the cylindrical case 3.
[0019]
An appropriate gap G is provided between the inner peripheral surface of the intermediate mold 14 and the outer peripheral surface of the cylindrical case 3 in order to facilitate the mold removal, and the flange portion is formed by the resin flowing into the gap G. An annular covering portion 16 is formed on the bottom surface of the base 9. Since the covering portion 16 is formed, the thickness t of the intermediate mold 14 for forming the annular recess 15 can secure the rigidity capable of maintaining a close contact state with the upper surface of the lower die 12. It can be.
[0020]
A column 17 integrally formed with the cylindrical case 3 is inserted at the base of the vertical portion 6 with respect to the head portion 5 in the elbow-shaped hose connection port 8. Thereby, the bending rigidity of the vertical part 6 in the hose connection port 8 is increased. Further, by providing this support column 17, for example, when a gate (not shown) is provided at a position facing the head portion 5, the resin flow to the vertical portion 6 is preferably guided, and as a result, surface defects such as burrs are obtained. Is suppressed.
[0021]
At the upper end portion of the support column 17, a step 18 is provided with a lower side where the horizontal portion 7 extends. As a result, the volume of the HDPE material flowing into the extended side and the non-extended side of the horizontal portion 7 at the connecting portion between the vertical portion 6 and the horizontal portion 7 is equalized, and surface defects such as sink marks occur. To prevent that.
[0022]
In both the vertical portion 6 and the horizontal portion 7, the internal passage P is formed by inserting a blank core (not shown) in advance.
[0023]
【The invention's effect】
As described above, according to the synthetic resin vent valve of the present invention , the bending rigidity of the hose connection port, in particular the vertical portion, is enhanced by the support column, so that the heat weldability of the vent valve heated and welded to the synthetic resin fuel tank is increased. It is possible to achieve a great effect in achieving both high strength and high strength.
[0024]
In particular, by adding a step provided at the upper end of the standoff, since the volume of the meat portion forming the elbow at the time of the post insert may equalization, on to prevent surface defects such as sink marks occur It is effective.
[0025]
Also, by providing the annular covering portion for covering the upper end portion outer peripheral surfaces of the valves body portion at the base of the lower surface of the flange portion, it is possible to increase the amount by the thickness dimension of the intermediate mold of the annular covering part, That is, the required rigidity can be imparted to the intermediate mold. Therefore, it becomes possible to form an annular recess at the base of the flange portion by two-color molding, and a great effect can be achieved in simplifying the structure of the synthetic resin vent valve.
[Brief description of the drawings]
FIG. 1 is an elevation view showing a part of a vent valve according to the present invention. FIG. 2 is a longitudinal sectional view of a main part showing a state where the vent valve is inserted into a mold.
DESCRIPTION OF SYMBOLS 1 Vent valve 4 Valve | bulb main-body part 5 Head part 6 Vertical part 7 Horizontal part 8 Hose connection port 9 Flange part 10 Gasoline barrier part 14 Intermediate mold 16 Cover part 17 Strut 18 Step

Claims (2)

A cylindrical case that is primarily molded from a resin material having higher strength than the resin material having heat-weldability, and that constitutes the valve body part;
A head part secondarily molded on the upper end of the cylindrical case by a resin material having heat-weldability ;
A hose connection port by secondary molding made of a resin material having a heat-welding property having an elbow shape including a vertical portion protruding from the central portion of the head portion and a horizontal portion extending from the upper end of the vertical portion; ,
A flange portion formed by secondary molding for mounting made of a resin material formed on the outer periphery of the head portion and having a heat welding property in a radially outward direction for heat welding to another component ;
A column inserted into the vertical portion of the hose connection port is integrally formed with the cylindrical case, and a step is formed at the upper end of the column with a lower side where the horizontal portion extends. The volume of the resin material flowing into the extended side and the non-extended side of the horizontal portion at the connecting portion between the vertical portion and the horizontal portion of the hose connection port is equalized. A synthetic resin vent valve. Plastic vent valve according to claim 1, characterized in that the base of the lower surface of the flange portion, an annular cover portion which covers the upper end portion outer peripheral surfaces of the tubular case is provided.

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