Abstract:
There is provided an oil strainer in which the assembling work can be performed very easily, and more over high quality can be ensured. An oil strainer  1  includes a housing  2  formed by closing an open portion  6  of a case body  3  by a cover body  20  and a filter element  30  disposed in the housing  2 . In the case body  3 , there is provided a groove portion  8  including a guide portion  9  for guiding the filter element  30  to the inside of the case body  3  by inserting both side edges of the filter element  30  into the inside and a locking portion  10  for locking the filter element  30  by inserting the tip end edge in the insertion direction of the filter element  30  into the inside.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an oil strainer that is used for vehicles and industrial machinery to filter oil. 
         [0003]    2. Description of the Related Art 
         [0004]    An oil strainer is generally made up of a housing for allowing oil to flow therein and a filter element disposed in the housing. An oil strainer of a type in which the housing is formed of a resin material is widely known. In the case where the housing is formed of a resin material, the oil strainer is completed mainly by molding a plurality of components in advance and by setting a filter element between these components and welding the components to each other. 
         [0005]    Patent Document 1 discloses one example of the conventional oil strainer. In this oil strainer, a pipe-form housing is formed by two resin-made components. At both ends in the axial direction of the housing, an inflow portion for allowing oil to be filtered to flow and an outflow portion for discharging the oil having been filtered are provided. A filter element is inserted through the inflow portion and is arranged in the housing, and the filter element is arranged so as to be held between the components. 
         [0006]    Further, Patent Document 1 discloses an oil strainer in which the filter element and one component are formed as one member. In this oil strainer, the housing includes a tubular component formed with an open portion and a flat plate shaped component that closes the open portion. The filter element is provided on the inner surface of the flat plate shaped component so as to be at right angles to the flat plate shaped component, and the filter element and the flat plate shaped component are formed as one member. 
         [0007]    In this oil strainer, on the inner surface of the tubular component, a locking portion for locking the tip end portion of the filter element is formed at a position facing to the open portion, and when both of the components are welded to each other, the tip end of the filter element is locked by the locking portion. 
         [0008]    [Patent Document 1] Japanese Patent Laid-Open No. 8-121138 
         [0009]    However, of the oil strainers disclosed in Patent Document 1, an oil strainer of a type in which the filter element is inserted has a disadvantage that the filter element may be damaged in the insertion process, and also the work for positioning the filter element is troublesome. 
         [0010]    Also, in the oil strainer of a type in which the filter element is held between the two components, poor weld may occur unless the joint portion of the components is fabricated into a special shape in advance. 
         [0011]    Further, in the oil strainer in which the filter element and one component are formed integrally, when the component formed integrally with the filter element is joined to the open portion formed in the tubular component, it is difficult to check whether the tip end of the filter element engages surely with the locking portion of the tubular component, so that it is difficult to perform the positioning work efficiently. 
         [0012]    In the case where the housing is formed by a plurality of components and is formed by welding these components, it is very difficult to perform vibration welding unless the strength or rigidity of the component is made high in advance. 
       SUMMARY OF THE INVENTION 
       [0013]    Accordingly, an object of the present invention is to provide an oil strainer in which the assembling work can be performed very easily, and moreover high quality can be ensured. 
         [0014]    To achieve the above object, the present invention provides an oil strainer including a housing ( 2 ,  51 ,  71 ) which is formed by a case body ( 3 ,  72 ) formed with an open portion ( 6 ,  85 ) and a cover body ( 20 ,  55 ,  90 ) which closes the open portion ( 6 ,  85 ) of the case body ( 3 ,  72 ), and allows oil to flow therein; a filter element ( 30 ,  60 ,  100 ) disposed in the housing ( 2 ,  51 ,  71 ) to filter oil flowing in the housing ( 2 ,  51 ,  71 ); and an inflow portion ( 15 ,  94 ) through which oil flows into the housing ( 2 ,  51 ,  71 ) and an outflow portion ( 16 ,  73 ) through which the oil having flown in the housing ( 2 ,  51 ,  71 ) flows out, wherein in the case body ( 3 ,  72 ), there is provided a groove portion ( 8 ,  80 ) including a guide portion ( 9 ,  81 ) for guiding the filter element ( 30 ,  60 ,  100 ) to the inside of the case body ( 3 ,  72 ) by inserting both side edges of the filter element ( 30 ,  60 ,  100 ) into the inside and a locking portion ( 10 ,  82 ) for locking the filter element ( 30 ,  60 ,  100 ) having been guided by the guide portion ( 9 ,  81 ) by inserting the tip end edge in the insertion direction of the filter element ( 30 ,  60 ,  100 ) into the inside; the groove portion ( 8 ,  80 ) is formed along the inner peripheral surface of the case body ( 3 ,  72 ) from one portion of a peripheral edge portion ( 6   a ,  86 ) of the open portion ( 6 ,  85 ) to the other portion thereof, and divides an interior of the case body ( 3 ,  72 ) into the dirty side (D) on which the inflow portion ( 15 ,  94 ) is disposed and the clean side (C) on which the outflow portion ( 16 ,  73 ) is disposed; and on the inner surface of the cover body ( 20 ,  55 ,  90 ), a holding portion ( 25 ,  57 ,  95 ) for fixing the position of the edge portion of the filter element ( 30 ,  60 ,  100 ) is formed so that both ends thereof coincide with the end portions of the groove portion ( 8 ,  80 ) formed on the case body ( 3 ,  72 ), and the peripheral edge of the filter element ( 30 ,  60 ,  100 ) is locked to the inside of the housing ( 2 ,  51 ,  71 ) by the groove portion ( 8 ,  80 ) and the holding portion ( 25 ,  57 ,  95 ). 
         [0015]    The present invention is characterized in that in the above-described oil strainer, the cover body ( 20 ,  90 ) and the filter element ( 30 ,  100 ) are integrated as one member by the holding portion ( 25 ,  95 ). 
         [0016]    In the above-described oil strainer, between the groove portion ( 8 ) of the case body ( 3 ,  72 ) and the peripheral edge of the filter element ( 30 ,  60 ,  100 ), there is formed a gap smaller than the dimension of the minimum dimension portion of a mesh hole forming a mesh ( 31 ,  61 ,  101 ) of the filter element ( 30 ,  60 ,  100 ). 
         [0017]    The present invention may be configured so that in the above-described oil strainer, the cover body ( 55 ) and the filter element ( 60 ) are formed as separate members, and the holding portion is a groove portion ( 57 ) in which the edge portion of the filter element ( 60 ) is inserted therein. In this case, between the groove portion ( 8 ,  57 ) formed on the case body ( 3 ) and cover body ( 55 ) and the peripheral edge of the filter element ( 60 ), there is formed a gap (δ) smaller than the dimension of the minimum dimension portion of a mesh hole forming a mesh ( 61 ) of the filter element ( 60 ). 
         [0018]    Also, in the present invention, in the peripheral edge portion ( 6   a ,  86 ) of the open portion ( 6 ,  85 ) formed on the case body ( 3 ,  72 ), the entire periphery thereof is formed in a state in which a member forming the case body ( 3 ,  72 ) is continuous and is closed in the peripheral direction. 
         [0019]    In this case, the inflow portion ( 15 ,  94 ) and the outflow portion ( 16 ,  73 ) are provided on the case body ( 3 ,  72 ) independently of the open portion ( 6 ,  85 ) so that the state in which the peripheral edge portion ( 6   a ,  86 ) of the open portion ( 6 ,  85 ) is closed is maintained. 
         [0020]    Also, the present invention is preferably configured so that in the above-described oil strainer, the housing ( 2 ,  51 ,  71 ) is formed so as to extend along one axis direction (X), the inflow portion ( 15 ,  94 ) is arranged on a first end side in the one axis direction (X), and the outflow portion ( 16 ,  73 ) is arranged on a second end side in the one axis direction (X); and the filter element ( 30 ,  60 ,  100 ) is arranged so as to extend in the one axis direction (X). 
         [0021]    In this case, the oil strainer can be configured so that in the case body ( 72 ), partition portions ( 78 ,  79 ) formed by projecting opposed side surface portions ( 76 ) toward the center are provided on the inflow portion ( 94 ) side and the outflow portion ( 73 ) side in the one axis direction (X); the partition portion ( 78 ) on the inflow portion ( 94 ) side is formed by projecting one of the side surface portions ( 76 ) and the partition portion ( 79 ) on the outflow portion ( 73 ) side is formed by projecting the other of the side surface portions ( 76 ); the in flow portion ( 94 ) and the out flow portion ( 73 ) are provided on the outside of the partition portions ( 78 ,  79 ) with respect to the one axis direction (X); for the groove portion ( 80 ), the guide portions ( 81 ) are formed in parallel with each other in opposed portions in the one axis direction (X) of the partition portions ( 78 ,  79 ), and the locking portion ( 82 ) is formed so as to connect the guide portions ( 81 ) to each other; the interior of the case body ( 3 ,  72 ) is divided into the dirty space (D) and the clean space (C) in the width direction of the case body ( 3 ,  72 ) by the groove portion  80 ; and the inflow portion ( 94 ) communicates with the dirty space (D) going around the partition portion ( 78 ), and the outflow portion ( 73 ) communicates with the clean space (C) going around the partition portion ( 79 ). 
         [0022]    According to the present invention, firstly, the oil strainer can be manufactured easily. 
         [0023]    Specifically, since the groove portion is formed in the case body, when the filter element is placed in the case body, the positioning can be performed very easily. Also, since the groove portion is formed by the guide portion and the locking portion, the filter element can be inserted into the case body smoothly by the guide portion for guiding the filter element, and the inserted filter element is surely locked to the groove portion consisting of the locking portion and the guide portion. 
         [0024]    Secondly, an oil strainer having a small manufacturing error and high quality can be obtained. 
         [0025]    Specifically, the present invention uses a configuration such that the groove portion is provided in the housing, and the filter element is locked by this groove portion. Therefore, unlike the conventional system in which the filter element is held by the components of the housing as in the conventional oil strainer, a gap caused by the positional shift etc. of the filter element is not formed between the components of the housing. 
         [0026]    Also, since the peripheral edge portion of the open portion formed on the case body is formed in a state of being closed throughout the entire periphery, the rigidity of the case body can be kept high. Because of the high rigidity, when the cover body is welded to the case body to assemble the oil strainer, deformation is less liable to occur. Thereby, an oil strainer with high accuracy can be formed. Also, because deformation is less liable to occur, measures against deformation need not be taken specially in the welding process, and welding work can be performed easily. 
         [0027]    Also, after the case body and the cover body have been welded to each other, an airtightness test is conducted to check whether or not any poor weld is present. According to the present invention, the process of the airtightness test can be simplified, and the test accuracy can be increased. That is to say, the airtightness test is conducted by hermetically sealing the inflow portion and the outflow portion and by causing air to flow from either of the inflow portion and the outflow portion. In this case, the air inflow portion must be sealed. However, since the open portion is independent of the in flow portion and the out flow portion, the sealing condition does not exert an influence on the weld portion. Therefore, the presence of defect can be checked quickly. Even if a defect is present, the position of defect can be determined easily. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is a perspective view of an oil strainer in accordance with a first embodiment of the present invention, in which the oil strainer is divided into components; 
           [0029]      FIG. 2  is a plan view of a case body; 
           [0030]      FIG. 3  is a plan view of a case body in accordance with a comparative example; 
           [0031]      FIG. 4  is a view showing an assemblingprocess of an oil strainer; 
           [0032]      FIG. 5  is a view showing one relationship between a frame portion of a filter element and a groove portion of a case body; 
           [0033]      FIG. 6  is an enlarged view showing one example of mesh holes forming a mesh portion; 
           [0034]      FIG. 7  is a perspective view of an oil strainer in accordance with a second embodiment of the present invention, in which the oil strainer is divided into components; 
           [0035]      FIG. 8  is a longitudinal sectional view of an oil strainer in accordance with a third embodiment of the present invention; 
           [0036]      FIG. 9  is a transverse sectional view of the oil strainer shown in  FIG. 8 ; and 
           [0037]      FIG. 10  is a plan view of a case body. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]    Embodiments of the present invention will now be described with reference to the accompanying drawings. 
         [0039]      FIGS. 1 to 6  show an oil strainer  1  in accordance with a first embodiment of the present invention. 
         [0040]    The oil strainer  1  includes a housing  2  that forms the outer shell of the oil strainer  1  and allows oil to flow therein and a filter element  30  disposed within the housing  2 . The housing  2  is made up of a case body  3  formed of a resin material and a cover body  20  formed of a resin material. Also, the filter element  30  and the cover body  20  are formed as one member. 
         [0041]    The case body  3  includes a side wall portion  4  and a bottom surface portion  5 , and an open portion  6  is formed at the upper part of the case body  3 . Also, the case body  3  is formed slenderly so as to extend in one axis direction X. The upper open portion  6  is formed so as to extend in one axis direction X corresponding to the shape of the case body  3 . 
         [0042]    Also, on the first end side in one axis direction X of the case body  3 , an inflow portion  15  through which oil flows in is provided so as to project from the side wall portion  4  toward the outside, and on the second end side thereof, an outflow portion  16  allowing the filtered oil to flow out is provided. 
         [0043]    On an inner surface  7  of the case body  3 , a groove portion  8  is formed in the side wall portion  4  and the bottom surface portion  5 . As shown in  FIG. 2 , the groove portion  8  is formed with a pair of groove walls  8   a  extending in parallel with each other so as to project from the inner surface  7  of the case body  3  toward the inside of the case body  3 . The groove portion  8  is formed along the inner surface  7  of the side wall portion  4  and the bottom surface portion  5  of the case body  3  so as to connect the first end side and the second end side in one axis direction X of a peripheral edge portion  6   a  of the open portion  6  to each other. 
         [0044]    The groove portion  8  divides the interior of the case body  3  into the dirty side D on which the inflow portion  15  is disposed and the clean side C on which the outflow portion  16  is disposed. The inflow portion  15  and the outflow portion  16  are disposed on the dirty side D and the clean side C, respectively. By forming the case body  3  in this manner, the filter element  30  positioned on the inside of the groove portion  8  divides the interior of the housing  2  into the dirty side D on which the inflow portion  15  is disposed and the clean side C on which the outflow portion  16  is disposed. 
         [0045]    Also, the peripheral edge portion  6   a  of the open portion  6  of the case body  3  is formed so as to be made continuous by a member forming the side wall portion  4  throughout the entire periphery in a state of being closed in the peripheral direction. In order to make the peripheral edge portion  6   a  of the open portion  6  in the closed state in this manner, in the case body  3 , both of the inflow portion  15  and the outflow portion  16  are provided under the open portion  6  independently of the open portion  6 . 
         [0046]    It is assumed that, like a case body  40  shown in  FIG. 3 , an open portion  41  is formed continuously with an inflow portion  42  and an outflow portion  43 , and an open portion for connecting the inside and outside of the case body  40  to a peripheral edge portion  42   a  is provided. In this case, the rigidity of the case body  40  decreases significantly. The decrease in rigidity easily produces a strain and makes it very difficult to finish the case body and the cover body to the designed size. Therefore, at the time of welding, the accuracy of the joint portion of the case body and the cover body decreases, which hinders the manufacture of a high-quality product. Also, in the welding process, the case body and the cover body may be deformed. This deformation also leads to the degradation of quality. 
         [0047]    On the other hand, as shown in  FIG. 1 , the cover body  20  is formed so as to have an external shape that is the same as the shape of the open portion  6  formed on the case body  3 . The peripheral edge of the cover body  20  coincides with the peripheral edge portion  6   a  of the open portion  6  of the case body  3 , so that by lapping the cover body  20  on the peripheral edge portion  6   a  of the open portion  6 , the open portion  6  of the case body  3  is closed. Also, the cover body  20  is formed with the filter element  30  integrally. The filter element  30  extends from an inner surface  21  of the cover body  20  perpendicularly to the cover body  20  in the center in the width direction of the cover body  20 . 
         [0048]    The filter element  30  includes a mesh portion  31  that allows oil to pass through and filters out impurities contained in the oil and a frame portion  32  surrounding the periphery of the mesh portion  31 . Also, the filter element  30  is provided with a center rib  33 , extending in parallel with the cover body  20 , at a substantially central position in the height direction. The shape of the frame portion  32  maybe formed individually so as to correspond to the shapes of the bottom surface portion  5  and the side wall portion  4  of the case body  3 . 
         [0049]    The cover body  20  with which the filter element  30  is integrated may be formed as one member by injection molding both of the filter element  30  and the cover body  20 , or may be formed by welding one side of the frame portion  32 , forming the filter element  30 , to the inner surface  21  of the cover body  20  after the filter element  30  and the cover body  20  have been formed separately. For both of the above modes, a boundary portion between the filter element  30  and the cover body  20  functions as a position holding portion  25  in which the position of the filter element  30  is fixed with respect to the cover body  20 . 
         [0050]    For the oil strainer  1  having the above-described construction, as shown in  FIG. 4 , the filter element  30  is inserted into the case body  3  so that the frame portion  32  of the filter element  30  is positioned on the inside of the groove portion  8 , by which the open portion  6  of the case body  3  is closed by the cover body  20 . At this time, the groove portion  8  formed in the side wall portion  4  functions as a guide portion  9  for guiding the filter-element  30  to the bottom surface portion  5  of the case body  3  while the positional shift of the filter element  30  is prevented. Also, the groove portion  8  formed in the bottom surface portion  5  functions as a locking portion  10  for locking the filter element  30 . Needless to say, the groove portion  8  formed in the side wall portion  4  also functions as a locking portion for inhibiting the positional shift of the filter element  30 . 
         [0051]    After the open portion  6  of the case body  3  has been closed by the cover body  20 , the peripheral edge of the cover body  20  and the upper end edge of the case body  3  are welded to each other to complete the oil strainer  1 . Although the welding method is not subject to any special restriction, the ultrasonic welding process is preferably used. 
         [0052]    In the completed oil strainer  1 , as shown in  FIG. 5 , a predetermined gap δ is formed between the groove portion  8  of the case body  3  and the frame portion  32  of the filter element  30 . This gap δ smoothly moves the filter element  30  in the groove portion  8 , functioning as the guide portion  9 , of the side wall portion  4  of the case body  3 . Also, the flatness of the groove portion  8  of the case body  3  and hence the filter element  30  and the perpendicularity of the filter element  30  with respect to the cover body  20  have errors inevitably. Due to the formation of the gap δ between the frame portion  32  and the groove portion  8 , the gap δ functions as a relief for the filter element  30  with respect to the groove portion  8 . Thereby, an unnecessary stress is prevented from being produced in the filter element  30 . 
         [0053]    The dimension of the gap δ is made smaller than the dimension d of the minimum dimension portion of a mesh hole  31   a  of the mesh portion  31 . For example, in the case where the mesh hole  31   a  is formed into a square shape as shown in  FIG. 6 , the minimum dimension portion of a mesh hole  31   a  is the dimension d between the opposite sides. The gap δ formed between the frame portion  32  and the groove portion  8  is formed so as to be smaller than the dimension d between the opposite sides. 
         [0054]    If the sum of both gaps formed between each surface of the frame portion  32  and each groove wall  8   a  of the groove portion  8  is smaller than the dimension d, even in the case where the filter element  30  is shifted to the one groove wall  8   a  side, the intrusion itself of impurities into the groove portion  8  can be prevented. Naturally, the gap between the bottom portion of the groove portion  8  and the frame portion  32 , the gap being made smaller than the dimension d, prevents impurities from passing between the bottom portion of the groove portion  8  and the frame portion  32  even if the impurities intrude into a portion between the groove wall  8   a  and the frame portion  32 . 
         [0055]    Next, an oil strainer  50  in accordance with a second embodiment of the present invention is described with reference to  FIG. 7 . 
         [0056]    In the oil strainer  50 , a housing  51  forming the outer shell of the oil strainer  50  is made up of a case body  3  and a cover body  55 , and the cover body  55  and a filter element  60  are formed as separate members. The construction of the case body  3  is the same as that of the case body  3  in accordance with the first embodiment. Herein, the same symbols are applied to the elements of the case body  3  that are equivalent to those in the first embodiment, and the explanation thereof is omitted. 
         [0057]    The cover body  55  is formed into a plate shape, and on the inner surface  56  side thereof, a groove portion  57  is formed in the center in the width direction thereof. The groove portion  57  extends along the above-described one axis direction X in which the housing  51  extends, and is formed so as to connect both end portions in one axis direction X of the cover body  55  to each other. In the groove portion  57  as well, a pair of opposed groove walls  57   a  are formed in parallel with each other. 
         [0058]    On the other hand, the filter element  60 , consisting of a plurality of mesh holes  61   a , includes a mesh portion  61  that allows oil to pass through and filters out impurities and a frame portion  62  provided so as to surround the periphery of the mesh portion  61 . Also, a center rib  63  extending in one axis direction X is provided at a substantially central position in the height direction. 
         [0059]    In the oil strainer  50  having the above-described construction in accordance with the second embodiment, one side  62   a  of the frame portion  62  of the filter element  60  is inserted into the groove portion  57  formed on the cover body  55 , and other side portions and the lower portion are inserted into a groove portion  8  formed on the inner surface of the case body  3 . Then, an open portion  6  formed at the upper part of the case body  3  is closed by the cover body  55 , and the peripheral edge of the coverbody  55  and a peripheral edge portion  6   a  at the upper part of the case body  3  are welded to each other. Thereby, the oil strainer  50  is completed. 
         [0060]    The oil strainer  50  in accordance with the second embodiment is formed so that when the open portion  6  of the case body  3  is closed by the cover body  55 , both ends in one axis direction X of the groove portion  57  formed on the cover body  55  coincide with the upper ends of the groove portion  8  formed in a side wall portion  4  of the case body  3 . Also, in the oil strainer in accordance with the second embodiment, a predetermined gap δ may also be formed between the groove portion  57  of the cover body  55  and the frame portion  62 . 
         [0061]    Next, a third embodiment is described with reference to  FIGS. 8 to 10 . 
         [0062]    An oil strainer  70  in accordance with the third embodiment also includes a housing  71  forming the outer shell of the oil strainer  70  and a filter element  100  disposed within the housing  71 . The housing  71  is made up of a case body  72  formed with an open portion  85  and a cover body  90  for closing the open portion  85 . This oil strainer  70  is also formed slenderly so as to extend in one axis direction X. 
         [0063]    The case body  72  is made up of a peripheral wall portion  76  and a top surface portion  77 , and the open portion  85  is formed on the bottom surface thereof. The first end side in one axis direction X is closed by the peripheral wall portion  76 , and on the other hand, the second end side is provided with an outflow portion  73  for allowing oil having passed through the housing  71  and having been filtered to flow out. Also, in the case body  72 , partition portions  78  and  79  projecting from one side surface portion  76   a  of the peripheral wall portion  76  toward the other opposed side surface portion  76   a  are formed. The partition portions  78  and  79  are formed at positions slightly on the inside from both ends in one axis direction X. 
         [0064]    Between the partition portions  78  and  79 , a groove portion  80  for locking the filter element  100  is formed. The groove portion  80  is formed continuously in a portion between the partition portions  78  and  79 , of the opposed surfaces of the partition portions  78  and  79  and the inner surface of the top surface portion  77 . A groove portion  81  in the partition portion  78 ,  79  is formed so as to extend vertically in the partition portion  78 ,  79  by recessing a part of the partition portion  78 ,  79  into a concave shape. On the other hand, a groove portion  82  formed in the top surface portion  77  of the case body  72  is formed by projecting the central portion in the width direction of the case body  72  to the outside along the one axis direction X. 
         [0065]    Further, in the case body  72 , space portions  83  and  84  are formed on the outside of the partition portions  78  and  79 , respectively, in one axis direction X. Of these space portions, the space portion  83  on the first end side in one axis direction X is connected to an inflow portion  94  provided in the cover body  90 , and the space portion  84  on the outflow portion  73  side forming the second end side is connected to the outflow portion  73 . As is apparent from  FIG. 10 , the space portion  83  on the inflow portion  94  side communicates with the upper range only with the groove portion  80  being a boundary, and is separated from the lower range by the partition portion  78 . On the other hand, the space portion  84  on the outflow portion  73  side communicates with the lower range only with the groove portion  80  being a boundary, and is separated from the upper range by the partition portion  79 . Thus, the groove portion  80  divides the interior of the case body  72  into the dirty side D on which the inflow portion  94  is disposed and the clean side C on which the outflow portion  73  is disposed. The inflow portion  94  communicates with the dirty side D going around the partition portion  78  via the space portion  83 , and the outflow portion  73  communicates with the clean side C going around the partition portion  79  via the space portion  84 . 
         [0066]    In the case body  72  as well, a peripheral edge portion  86  of the open portion  86  is continuous throughout the entire periphery and is in a state of being closed. As shown in  FIG. 9 , the peripheral edge portion  86  includes a contact surface  87  projecting from the peripheral wall portion  76  toward the outside at the lower end of the case body  72  and an outer peripheral wall  88  projecting further toward the downside at the outer peripheral edge of the contact surface  87 . 
         [0067]    On the other hand, the cover body  90  is formed into a plate shape, and the external shape thereof is the same as the shape of the open portion  85  formed on the case body  72 . The cover body  90  is inserted into the inside of the outer peripheral wall  88  forming the peripheral edge portion  86  of the open portion  85  of the case body  72 , and is lapped on the contact surface  87  forming the peripheral edge portion  86 , by which the open portion  85  of the case body  72  is closed. 
         [0068]    On the first end side in one axis direction X of the cover body  90 , the inflow portion  94  extending from an outer surface  91  of the cover body  90  is formed. The inflow portion  94  is allowed to communicate with the space portion  83  formed in the case body  72  when the cover body  90  closes the open portion  85  of the case body  72  and is integrated with the case body  72 . 
         [0069]    Also, the cover body  90  is integrally formed with the filter element  100 . The filter element  100  extends from an inner surface  92  of the cover body  90  at right angles to the cover body  90  in the center in the width direction of the cover body  90 . Both ends of the filter element  100  are arranged at the inside positions separating predetermined distances Z 1  and Z 2  from both ends in one axis direction X. The predetermined distances Z 1  and Z 2  correspond to the distances Y 1  and Y 2  between both ends in one axis direction X of the case body  72  and guide portions  81  formed in the partition portions  78  and  79  (refer to  FIG. 10 ), and the length of the filter element  100  corresponds to the distance between the guide portions  81 . The filter element  100  includes a mesh portion  101 , a frame portion  102  surrounding the periphery of the mesh portion  101 , and a center rib  103  provided in a cross shape. The process for the integration can be performed in the same way as in the first embodiment. 
         [0070]    For the oil strainer  70  having the above-described construction as well, the frame portion  102  of the filter element  100  is positioned on the inside of the groove portion  80  of the case body  72 . The groove portion  80  formed in the partition portion  78 ,  79  functions as a guide portion for guiding the filter element  100  from the open portion  85  side to the top surface portion  77  of the case body  72 . Also, the groove portion  80  in the top surface portion  77  functions as a locking portion, and thus the filter element  100  is locked to this groove portion  80 . In the oil strainer  70  of this embodiment as well, a gap smaller than the dimension of the minimum dimension portion of a mesh hole is formed between the frame portion  102  of the filter element  100  and the groove portion  80 . Also, the case body  70  and the cover body  90  are welded to each other by ultrasonic welding etc. 
         [0071]    In the oil strainer in accordance with the third embodiment, both ends of the filter element  100  are locked to the groove portions  80  formed in the partition portions  78  and  79  as guide portions  81 . Therefore, as compared with the case where the groove portion  80  is provided directly on the case body  72 , the oil strainer  70  has a construction that is less liable to transmit vibrations to the filter element  100 , and hence is invulnerable to vibrations. 
         [0072]    Also, for this third embodiment as well, the cover body and the filter element may be provided as separate members. In this case, a groove portion in which the frame portion of the filter element is inserted is formed on the inner surface of the cover body. The groove portion formed on the cover body is formed so that both ends thereof coincide with the upper ends of the groove portions formed in the partition portion of the case body. 
         [0073]    In the above-described embodiments, the oil strainer having the cover body formed into a plate shape has been explained as an example. However, the shape of cover body is not limited to this shape. A cover body having an arcuate transverse cross section may be used. Also, the example in which the groove portion is formed continuously in the extension direction thereof has been explained. However, since the gap formed between the frame portion of the filter element and inside surfaces of the case body and cover body is formed so as to be smaller than the minimum dimension of the mesh hole, a break may be provided at an intermediate position of the groove portion, or the groove portion may be formed intermittently. 
         [0074]    The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. 
         [0075]    The entire disclosure of Japanese Patent Application No. 2006-011511 filed on Jan. 19, 2006 including the specification, claims, drawings and summary is incorporated herein by reference in its entirety.