Abstract:
A filter device includes a main body with a tubular shape having at least two outflow openings formed in a sidewall thereof with an interval in between around a tube axis for passing fluid such as oil; and a filter member with a tube shape embedded in the main body around the tube axis thereof to pass column portions formed between the outflow openings for closing the outflow openings. At least one of the column portions has a groove formed in an inner surface thereof to extend along the tube axis of the main body.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT  
       [0001]     The present invention relates to a filter device disposed at an outlet of a pipe forming a fluid passage of fluid such as oil for filtering foreign materials in the fluid flowing out of the outlet, and a method of manufacturing the same.  
         [0002]     Japanese Patent Publication (Kokoku) No. 06-11372 has discloses an oil strainer, and a filter device formed of a plastic tube is shown in  FIG. 10 . As shown in  FIG. 10 , such a filter device has a cylindrical shape with an open end and a closed end. Outflow openings  300  are formed in a sidewall of the filter device and closed with a filter member  301 . The filter device is fitted into an outlet Pa of a pipe P for filtering foreign materials in fluid such as oil flowing out of the pipe P.  
         [0003]     When the filter device is molded with injection molding, the filter member  301  formed in a cylindrical shape in advance is placed as an insert outside of a male mold  100  for forming an inner portion of the filter device. The filter member  301  thus inserted closes the outflow openings  300 . Column portions  302  are molded with grooves  101  formed in the male mold  100  and grooves  201  formed in a female mold  200 , and situated between the outflow openings  300 . The filter member  301  passes through the column portions  302 .  
         [0004]     When the filter device is molded, a molten resin is injected into the molds at a high pressure, and the filter member  301  is pushed inwardly at the column portions  302  by the pressure. In this case, a part of the filter member  301  may be extended tightly, and another part of the filter member  301  may be loose between the outflow openings  300 , thereby causing uneven tension in the filter member  301 . In the injection molding, the molten resin is injected at a higher pressure at a location closer to a gate opening (X in  FIG. 11 ). Accordingly, the filter member  301  tends to be pushed easily with the resin into the groove  101  of the male mold  100  located close to the gate opening. On the other hand, at a position away from the gate opening, the resin is injected with a lower pressure. Accordingly, the filter member  301  is pushed into the groove  101  with a lower pressure, thereby loosening the filter member  301 . (The resin is not shown in  FIG. 11 .)  
         [0005]     In view of the problems described above, an object of the present invention is to provide a filter device formed of plastic and having several outflow openings closed with a filter member, in which the filter member is inserted in a sidewall of the filter device with uniform tension.  
         [0006]     Further objects and advantages of the invention will be apparent from the following description of the invention.  
       SUMMARY OF INVENTION  
       [0007]     In order to attain the objects described above, according to the present invention, a filter device includes the following three features (1) to (3): (1) a main body with a tubular shape having at least two outflow openings formed in a sidewall thereof with an interval in between around a tube axis for passing fluid such as oil; (2) a filter member with a tube shape inserted in the main body around the tube axis thereof and passing through column portions formed between the outflow openings for closing the outflow openings; and (3) at least one of the column portions having a groove formed in an inner surface thereof and extending along the tube axis of the main body.  
         [0008]     With this structure, when the filter device is molded, a part of the male mold for forming the groove, i.e., a rib formed on the male mold, supports the filter member from inside. As a result, in the column portions formed between the outflow openings, it is possible to prevent the filter member from being pushed excessively into the main body with a pressure of a resin injected into the mold. It is also possible to prevent a case in which the filter member closes a part of the outflow openings  12  with a high tension, and closes other part of the outflow openings  12  with a low tension.  
         [0009]     The resin is injected into the mold through the gate opening to form the main body. At least one of the column portions may have an outer side portion facing the gate opening of the mold and opposite to the groove formed in the inner surface of the column portion.  
         [0010]     With this structure, it is possible to prevent the filter member from being pushed excessively into the main body at a position where the resin is injected with a highest pressure.  
         [0011]     At least one of the column portions may have more than two grooves formed in the inner surface thereof.  
         [0012]     With this structure, it is possible to prevent the filter member from being pushed excessively into the main body with more than two ribs formed on the male mold for forming the grooves.  
         [0013]     According to the present invention, a tube shaped filter member is placed in a cavity between a male mold and a female mold. The male mold forms an inner portion of a tubular main body, and the female mold forms an outer portion of the tubular main body. The male mold has a groove in an inner surface of a portion thereof for forming a column portion of the main body. Then, a resin is injected into the cavity between the male mold the female mold to form the main body of a filter device.  
         [0014]     In the method, when the main body is molded, the rib provided on the male mold supports the filter member from inside. Accordingly, it is possible to form the filter device while preventing the filter member from being excessively pushed into the main body by a pressure of the resin injected into the mold in the column portion between outflow openings.  
         [0015]     According to the present invention, the filter member closes the outflow openings formed in the sidewall of the main body constituting the filter device with uniform tension. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a front view of a filter device according to the present invention;  
         [0017]      FIG. 2  is a plan view of the filter device;  
         [0018]      FIG. 3  is a bottom view of the filter device;  
         [0019]      FIG. 4  is a cross sectional view taken along line  4 - 4  in  FIG. 2 ;  
         [0020]      FIG. 5  is a cross sectional view of the filter device and a pipe P in a separated state;  
         [0021]      FIG. 6  is a cross sectional view of the filter device in use;  
         [0022]      FIG. 7  is a sectional view of an essential part of a mold of the filter device;  
         [0023]      FIG. 8  is a sectional view an essential part of the filter device molded from the essential part of the mold shown in  FIG. 7 ;  
         [0024]      FIG. 9  is a modified example of the filter device shown in FIGS.  1  to  8 ;  
         [0025]      FIG. 10  is a perspective view of a conventional filter device; and  
         [0026]      FIG. 11  is a cross sectional view of a mold of the conventional filter device. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0027]     Hereunder, embodiments of the present invention will be described in detail with reference to FIGS.  1  to  9 .  
         [0028]      FIG. 1  and  FIG. 4  show a filter device F according to an embodiment of the present invention.  FIG. 5  shows the filter device F and a tube P to be inserted into the filter device F in a separated state.  FIG. 6  shows an outlet Pa of the tube P inserted into the filter device F in an enlarged sectional view of an essential part of the filter device F.  FIG. 7  is a partial sectional view of a mold for forming a column portion  17  located between outflow openings  12  of the filter device F.  FIG. 8  shows a sectional view of an essential part of the filter device F molded with the part of the mold.  FIG. 9  is a sectional view of an essential part of the filter device having three grooves  17   a ,  17   a , and  17   a  formed in an inner surface  17   b  of the column portion  17 .  
         [0029]     In the embodiment, the filter device F is attached to the outlet Pa of the tube P forming a passage of fluid such as oil for filtering foreign materials in fluid flowing out of the outlet Pa.  
         [0030]     The tube P includes a metal tube or pipe, and a rubber or plastic tube or pipe.  
         [0031]     The filter device F has a main body  1  and a filter member  2 . The main body  1  has an open one end  10  and a closed other end  11 . In the embodiment shown in the drawings, the main body  1  is formed in a cylindrical shape. The pipe P is also formed in a cylindrical shape, and inserted into the main body  1  from the open end  10 .  
         [0032]     The main body  1  has outflow openings  12  in a side portion thereof closed with the filter member  2  for passing fluid such as oil. Accordingly, the filter member  2  captures foreign materials in fluid flowing out the outlet Pa of the pipe P, and fluid flows out of the outflow openings  12  after being filtered. In the embodiment, the outflow openings  12  are formed in an elongated rectangular shape extending along a tube axis of the main body  1 . A plurality of the outflow openings  12  is formed in the side portion of the main body  1  with a distance in between around the tube axis of the main body  1 .  
         [0033]     The open end  10  of the filter device F is provided with an introduction part  13  having an inner diameter slightly larger than an outer diameter of the outlet Pa; a pressure receiving part  14  adjacent to the introduction part at an inner side and having an inner diameter slightly smaller than an outer diameter of the outlet Pa; and a guide part  15  formed of a plane inclined toward the pressure receiving part  14  and disposed between the introduction part  13  and the pressure receiving part  14 .  
         [0034]     In the embodiment, the introduction part  13  is formed between an end of the open end  10  of the main body  1  and the guide part  15 . The introduction part  13  is formed of a first circumference surface  13   a  inside the main body  1  having a surface extending around the tube axis of the main body  1  and substantially in parallel to the tube axis. A curved surface  18  is formed at an inner end of the tube end  10  of the main body  1 .  
         [0035]     The pressure receiving part  14  extends from the guide part  15  toward an inner side of the main body  1 , i.e., toward the closed end  11 . The pressure receiving part  14  is formed of a second circumference surface  14   a  inside the main body  1  and having a surface extending around the tube axis and substantially in parallel to the tube axis. The pressure receiving part  14  extends toward the tube end  10  to a position away from opening edges of the outflow openings  12  by a specific distance. The pressure receiving part  14  is provided with a circumference step  16  facing the tube end  10  at an end portion thereof. The outlet Pa of the pipe P is inserted into the main body  1  close to the circumference step  16  from the tube end  10  of the main body  1 .  
         [0036]     The guide part  15  is formed of a circumference inclined surface  15   a  in the main body  1  inclined closer to the tube axis toward the pressure receiving part  14  and extending around the tube axis of the main body  1 .  
         [0037]     The introduction part  13  has an inner diameter slightly larger than an outer diameter of the outlet Pa of the pipe P. Accordingly, with the introduction part  13 , it is possible to easily insert the outlet part Pa into the filter device F from the tube end  10  of the filter device F without shifting between an axis of the Pipe P and an axis of the filter device F, while minimizing an influence of the insertion on the filtering device  2 . When the outlet Pa is inserted further inside, the outlet Pa is guided to the pressure receiving part  14  along the inclined surface of the guide part  15 . Accordingly, the filter device F expands elastically, so that the outlet Pa is fitted into the pressure receiving part  14 , thereby stably attaching the filter device F to the outlet Pa. The injection receiving part  14  formed adjacent to the introduction part  13  at the tube end  10  is fitted. The introduction part  13  prevents the injection receiving part  14  from deforming when the outlet Pa is inserted into the injection receiving part  14 .  
         [0038]     The filter member  2  is formed in a cylindrical shape around the tube axis of the main body  1 , and passes through the column portions  17  formed between the outflow openings  12  of the main body  1  to close the outflow openings  12 . In the embodiment, the main body  1  is made of plastic with general plastic injection molding while the filter member  2  is inserted. The filter member  2  is formed of mesh, and may be formed of unwoven cloth.  
         [0039]     Specifically, a male mold  100  for forming an inner portion of the main body  1  is inserted into the filter member  2  with a cylindrical shape, thereby forming the main body with the filter member  2  as an insert.  
         [0040]     The main body  1  has one or more than two grooves  17   a  extending along an axis direction of the main body  1  in an inner portion  17   b  of the column portion  17 .  
         [0041]     With this structure, a part of the male mold  100  for forming the groove  17   a , i.e., a rib  102  provided on the male mold  100 , can support the filter member  2  from inside when the main body is molded. As a result, in the column portion  17  formed between the outflow openings  12  of the main body  1 , it is possible to prevent the filter member  2  from being excessively pushed into the main body  1  with a pressure of a resin injected into the mold upon molding. It is also possible to prevent a case in which the filter member  2  closes a part of the outflow openings  12  with a high tension, and closes other part of the outflow openings  12  with a low tension.  
         [0042]     The groove  17   a  in the column portion  17  of the main body  1  is formed inside the groove  101  of the inner portion  17   b  of the column portion  17  with the rib  102  formed in the male mold  100  such as core pin for forming the inner portion of the main body  1 , thereby forming the filter device F appropriately.  
         [0043]     Specifically, a female mold  200  for forming an outer portion  17   c  of the main body  1  is provided with a groove  201  along a removal direction of the male mold  100 . The male mold  100  for forming the inner portion  17   b  of the main body  1  is provided with the groove  101  along the removal direction of the male mold  100 . The outer portion  17   c  of the column portion  17  is formed with the groove  201  of the female mold  200 , and the inner portion  17   b  of the column portion  17  is formed with the groove of the male mold  100 . The filter member  2  is placed outside the male mold  100 , and passes through the column portion  17 . When the male mold  100  is inserted into the female mold  200 , a pitch of a wall thickness of the filter member  2  is formed between the female mold  200  and the male mold  100  at both sides of the grooves  101  and  201 . Accordingly, it is possible to form the outflow openings  12  closed with the filter member  2  at both sides of the column portion  17 . The rib  102  extending in the removal direction of the male mold  100  is provided inside the groove  101  formed in the male mold  100 . In the embodiment, the rib  102  has a projecting end located on a surface same as an outside surface of the male mold  100  at sides of the groove  101 . As shown in  FIG. 9 , when the column portion  17  is provided with the three grooves  17   a ,  17   a , and  17   a , two ribs  102  are provided inside the groove  101  of the male mold  100 .  
         [0044]     In this case, the ribs  102  provided in the male mold  100  support the filter member  2  from inside upon molding in the column portion  17  formed between the outflow openings  12 . Accordingly, it is possible to prevent the filter member  2  from being excessively pushed into the main body  1  with a pressure of a resin injected into the mold, thereby forming the filter device F appropriately (refer to  FIG. 7  and  FIG. 8 ). In the embodiment, a concave part  17   e  is formed at a middle of the outer portion  17   c  of one of the column portions  17 . A gate opening  202  of the female mold  200  is located at a portion for forming the concave part  17   e . Accordingly, the filter member  2  receives a highest pressure of a resin in the column portion  17  provided with the concave part  17   e . The rib  102  of the male mold  100  for forming the groove  17   a  of the column portion  17  prevents the filter member  2  passing through the column portion  17  from being pushed excessively.  
         [0045]     In the embodiment, the main body  1  is provided with six outflow openings  12 , and the column portions  17  are formed at six places. Two of the column portions  17  at opposed positions have sidewalls  17   d  extending in a thickness direction between inner walls and outer walls thereof and located on an imaginary first line X. The other column portions  17  between the two column portions  17  have sidewalls  17   d  extending in a thickness direction between inner walls and outside walls thereof and located on an imaginary second line Y substantially perpendicular to the first line X. Accordingly, the female mold  200  is formed of two parts divided along a parting line located at a middle of a width of the two column portions  17  with the sidewalls  17   d  located on the imaginary first line X. In the embodiment, an end portion of the filter member  2  at a side of the tube end  10  of the main body  1  is inserted in the main body  1  beyond opening edges of the outflow openings  12  at the side of the tube end  10 . An end portion of the filter member  2  at a side the other tube end  11  of the main body  1  is inserted and supported in the main body  1  beyond opening edges of the outflow openings  12  at the side of the other tube end  11 . According to the embodiments of the present invention, the filter device F described above is used for filtering fluid flowing into the main body  1  from the tube end  10 , and may be used for filtering fluid flowing into the main body  1  through the outflow openings  12 .  
         [0046]     The disclosure of Japanese Patent Application No. 2003-423512, filed on Dec. 19, 2003, is incorporated in the application.  
         [0047]     While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.