Abstract:
A method of adjusting a capacity of a tank, including providing a mold assembly for the tank, the mold assembly configured to form the tank having a first full capacity, and installing an insert block in a cavity of the mold assembly, the mold assembly and insert block configured to form a tank having a second full capacity, the second full capacity being less than the first full capacity. A tank includes a tank main body, and an insert portion extending substantially vertically within the tank main body. A ratio between a substantially horizontal cross-sectional area of the insert portion, and a substantially horizontal cross-sectional area of an inside of the tank main body from which the cross-sectional area of the insert portion is removed, is substantially constant.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2006-189340, filed on Jul. 10, 2006, the disclosure of which is incorporated by reference herein in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a tank, and more particularly to a method of adjusting the capacity of a tank, a method of producing a tank by the adjusting method and, a tank produced by the adjusting method. 
         [0004]    2. Description of Related Art 
         [0005]    In recent years, there is a tendency to share a vehicle platform having a basic automotive body design portion among a plurality of kinds of vehicles. When the platform is shared in this manner, a fuel tank of the same specification can also be shared. However, if a fuel tank is shared, the full tank capacity for some vehicles must be changed in relation to the vehicle weight and cruising distance. 
         [0006]    The amount of fuel in a fuel tank can be confirmed by a fuel gauge disposed at an instrument panel, the fuel gauge being adapted to measure a height of the surface of the fuel by using a float and a potentiometer, and to indicate a measured value at the gauge. Specifically, the float moves upward and downward in response to a variation of a height of the surface of the fuel, and the potentiometer recognizes the position of the float as a variation of electric resistance and indicates the variation of the resistance value by the fuel gauge. 
         [0007]    However, in a conventional automotive vehicle in which a platform is shared, a full tank capacity of a commonly used tank is changed. For example, if the full tank capacity is decreased, a full tank height is naturally lowered such that a lowered full tank fuel surface position, i.e., a lowered float position, is indicated as full by a fuel gauge. 
         [0008]    For this reason, when the full tank capacity is decreased, a corresponding new fuel gauge needs to be provided—for example, a resistance base plate and a float arm needs to be provided separately, thus increasing costs. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    The present invention relates to overcoming the disadvantages of the related art by providing a method of adjusting a tank capacity, which enables sharing of a fuel gauge, and a tank produced by using the adjusting method. 
         [0010]    In an embodiment, the invention provides a method of adjusting a capacity of a tank, including providing a mold assembly for the tank, the mold assembly configured to form the tank having a first full capacity, and installing an insert block in a cavity of the mold assembly, the mold assembly and insert block configured to form a tank having a second full capacity, the second full capacity being less than the first full capacity. 
         [0011]    In another embodiment, the invention provides a tank, including a tank main body, and an insert portion extending substantially vertically within the tank main body. A ratio between a substantially horizontal cross-sectional area of the insert portion, and a substantially horizontal cross-sectional area of an inside of the tank main body from which the cross-sectional area of the insert portion is removed, is substantially constant. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate preferred embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain features of the invention. 
           [0013]      FIG. 1  is a perspective view of a tank according to an embodiment of the invention; 
           [0014]      FIG. 2  is an enlarged sectional view taken along the line II-II of  FIG. 1 ; 
           [0015]      FIG. 3  is a sectional view of a mold assembly for molding the tank of  FIG. 1 ; and 
           [0016]      FIG. 4  is a diagram representing a relation between a tank of a first full capacity or a second full capacity according to the embodiment, and a fuel gauge. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]      FIGS. 1 to 4  show a method of producing a tank, and a tank produced by the method according to an embodiment of the invention, wherein  FIG. 1  is a perspective view of a tank,  FIG. 2  is an enlarged sectional view taken along the line  11 - 11  of  FIG. 1 ,  FIG. 3  is a sectional view of a mold assembly for molding the tank, and  FIG. 4  is a diagram representing a relation between a tank of a first full capacity or a second full capacity, and a fuel gauge. As used herein, a full tank height indicates a height of a liquid surface from a bottom surface of a tank when the tank is full. 
         [0018]      FIG. 1  illustrates a tank  1  having a basic, first full tank capacity A. The tank  1  is adapted for use with a shared automobile platform, and particularly a vehicle that requires the full tank capacity A of the tank  1  to be decreased. 
         [0019]    The tank  1  is integrally molded from synthetic resin (e.g. parison) formed in a closed space by blow molding or the like. An insert portion  10  is provided inside the tank  1  as shown in  FIG. 2  to decrease the capacity inside the tank  1  and produce a second full capacity B so that the first full capacity A and the second full capacity B attain nearly the same full tank height H. 
         [0020]    The method of producing the above-described tank  1  includes providing the insert portion  10  inside the tank  1  of the first full capacity A to decrease the capacity inside the tank  1  and provide the second full capacity B, and determining the shape of the insert portion  10  so that the first full capacity A and the second full capacity B attain nearly the same full tank height H. In this connection, the full tank height H is the height of the liquid surface from the bottom surface of the tank  1 . 
         [0021]    The insert portion  10  includes two bottle-shaped insert sections, i.e., a first insert section  11  and a second insert section  12  having at one vertical end side straight tubular parts  11   a  and  12   a , and at the other end side tapered parts  11   b  and  12   b . The first and second insert sections  11  and  12  are inverted relative to each other, such that the first insert section  11  is disposed so that the tubular part  11   a  is positioned upward and the tapered part  11   b  is positioned downward, while the second insert section  12  is disposed so that the tubular part  12   a  is positioned downward and the tapered part  12   b  is positioned upward. 
         [0022]    Accordingly, the internal volume of the tank  1  of the full tank capacity A is adapted to provide the full tank capacity B (A&gt;B) by the provision of the first and second insert sections  11  and  12 . 
         [0023]    As shown in  FIG. 1 , the first insert section  11  and the second insert section  12  are configured through design of horizontal sectional areas S 1 ( h ) and S 2 ( h ) with respect to the height h (h=0 to H), such that the horizontal area of fuel at a given height h of the tank  1  when the insert portion  10  is not provided, compared to when the insert portion  10  is provided, satisfies a particular relation. In particular, assuming that S(h) denotes the horizontal area of fuel when the insert portion  10  is not provided, the horizontal area of fuel when the insert portion  10  is provided is denoted by [S(h)−{S 1 ( h )+S 2 ( h )}]. The ratio between both areas is determined to be equal to the ratio between the first full tank capacity A when the insertion portion  10  is not provided, and the second full tank capacity B when the insertion portion  10  is provided, as shown by the following equation. 
         [0000]        S ( h ):[ S ( h )−{ S 1( h )+ S 2( h )}]= A:B   Equation (1) 
         [0024]    A mold assembly  20  for molding the tank  1  includes an upper mold member  21  and a lower mold member  22  as shown in  FIG. 3 , and is configured to mold the tank  1  by blow molding by inserting a parison into a cavity  23  at joining portions of the upper mold member  21  and the lower mold member  22 . 
         [0025]    In this instance, the first and second insert sections  11  and  12  of the above-described insert portion  10  are molded by an insert block unit  30  detachably installed in the cavity  23  of the above-described mold assembly  20 . 
         [0026]    Namely, the above-described insert block unit  30  includes of a plurality of insert blocks, e.g., an upper mold insert block  31  attached to the upper mold member  21  to protrude toward the lower mold member  22  for molding the first insert section  11 , and a lower mold insert block  32  attached to the lower mold member  22  to protrude toward the upper mold member  21  for molding the second insert section  12 . 
         [0027]    Then, a base end portion  31   a  of the upper mold insert block  31 , i.e., the portion  31   a  at which the upper mold insert block  31  is received in the upper mold member  21 , and a base end portion  32   a  of the lower mold insert block  32 , i.e., the portion  32   a  at which the lower mold insert block  32  is received in the lower mold member  22 , have a minimum draft angle at an outer side. Further, by a leading end portion  31   b  of the upper mold insert block  31 , i.e., the portion  31   b  at which the upper mold insert block  31  is received in the lower mold member  22 , and a leading end portion  32   b  of the lower mold insert block  32 , i.e., the portion  32   b  at which the lower mold insert block  32  is received in the upper mold member  21 , the horizontal sectional area of the insert unit  10  is mainly adjusted based on the above-described equation (1). 
         [0028]    The base end portion  31   a  of the above-described upper mold insert block  31  corresponds to the tubular part  11   a  of the first insert section  11 , the base end portion  32   a  of the lower mold insert block  32  corresponds to the tubular part  12   a  of the second insert section  12 , while the leading end portion  31   b  of the upper mold insert block  31  corresponds to the tapered part  11   b  of the first insert section  11 , and the leading end portion  32   b  of the lower mold insert block  32  corresponds to the tapered part  12   b  of the second insert section  12 . 
         [0029]    Accordingly, in this embodiment, the above-described tank  1  attains the first full capacity A when not provided with the above-described insert portion  10 , and the second full capacity B when provided with the insert portion  10 , and further attains nearly the same full tank height H in each case. 
         [0030]    In this instance, in the tank  1  adapted to attain the first full capacity A, as shown in  FIG. 4 , fuel capacity V-needle indication characteristics  6  are adapted so as to be linear by making fuel capacity V-liquid surface height h characteristics be α, gauge characteristics be β, and fuel gauge indication characteristics γ be linear. When tank  1  is provided with insert portion  10  by the above-described method to attain the second full capacity B, fuel capacity V-liquid surface height h characteristics α′ is attained, thus enabling sharing of the above-described gauge characteristic β and thereby enabling to attain the fuel capacity V-liquid surface height h characteristics α′ by using the same fuel gauge. 
         [0031]    By the method of manufacturing the fuel tank  1 , and by the tank  1  obtained by using the method described above, when the tank  1  of the first full capacity A is provided with the insert portion  10  to attain the second full capacity B, the first full capacity A and the second full capacity B can attain nearly the same full tank height H, thus enabling the full tank positions of the floats for measuring the liquid surface position to be nearly the same, and therefore enabling the fuel gauge for use with the tank  1  of the first full tank capacity A to be shared with the tank  1  of the second full capacity B. For this reason, in case the full tank capacity is decreased from A to B, it is not necessary to provide a new fuel gauge, thus preventing increased costs. 
         [0032]    Further, the above-described insert portion  10  is formed by the first insert section  11  and the second insert section  12 , the sectional areas S 1 ( h ) and S 2 ( h ) of the first and second insert sections  11  and  12  with respect to the horizontal direction relative to the height direction is adjusted so that the ratio between the horizontal area of fuel S(h) when the insert portion  10  is not provided, and the horizontal area of fuel [S(h)−{S 1 ( h )+S 2 ( h )}] when the insert portion  10  is provided, is equal to the ratio between the first full tank capacity A and the second full tank capacity B (refer to equation (1)), thus improving the accuracy in the needle indication of the fuel gauge when the tank  1  is other than full. 
         [0033]    Further, since the above-described tank  1  is adapted to be integrally molded by using the mold assembly  20 , and the above-described insert portion  10  including the first and second insert sections  11  and  12  is formed by the insert block unit  30  being detachably installed in the cavity of the mold assembly  20 , the tank  1  of the first full capacity A can be molded by detaching the insert block unit  30  from the mold assembly  20 , while the tank  1  of the second full capacity B can be molded by installing the insert block unit  30  in the mold assembly  20 , thus enabling two kinds of tanks  1  that differ in the full tank capacity to be produced with ease, by providing the insert block unit  30  or not. 
         [0034]    Further, since the above-described insert block unit  30  includes a plurality of insert blocks, e.g., the upper mold insert block  31  attached to the upper mold member  21  to protrude toward the lower mold member  22  for molding the first insert section  11  and the lower mold insert block  32  attached to the lower mold member  22  to protrude toward the upper mold member  21  for molding the second insert section  12 , the base end portion  31   a  of the upper mold insert block  31  and the base end portion  32   a  of the lower mold insert block  32  being configured to have a minimum draft angle at an outer side, and the horizontal sectional area of the insert portion  10  being mainly adjusted by the leading end portion  31   b  of the upper mold insert block  31  and the leading end portion  32   b  of the lower mold insert block  32 , the upper mold insert block  31  and the lower mold insert block  32  are tapered toward the respective mold members facing the mold members to which they are attached, thus enabling the mold members to be removed with ease and also enabling the sectional area of the insert portion  30  to be adjusted by the plurality of leading end parts  31   b  and  32   b  such that the sectional area can be adjusted more widely and accurately. 
         [0035]    While the invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the invention, as defined in the appended claims and equivalents thereof. For example, while the insert block unit  30  has been described as including two insert blocks, i.e., the first and second insert blocks  31  and  32 , the insert block unit can include three or more blocks. Moreover, the shape of the insert block unit is not limited to a bottle shape of a circular cross section, but may be any shape that can attain easy adjustment of the horizontal area of liquid. Also, the invention has been described in one embodiment as pertaining to a fuel tank. However, the invention may pertain to any liquid tank. Accordingly, it is intended that the invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims.