Patent Publication Number: US-2019193009-A1

Title: Filter device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of International Patent Application No. PCT/JP2017/029256 filed on Aug. 14, 2017, which claims priority to Japanese Patent Application No. 2016-176138 filed on Sep. 9, 2016, the entire contents of which are incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a filter device. 
     BACKGROUND ART 
     Patent Document 1 discloses a filter device in which a filter cartridge configured to house a filter element in a casing is detachably attached to a head including an inflow port and an outflow port. In the filter device described in Patent Document 1, the filter cartridge is detachably attached to the head via a nut provided on the outer circumference of the casing. 
     CITATION LIST 
     Patent Document 
     Patent Document 1: JP 4033739 B 
     However, in the invention described by Patent Document 1, water or foreign matter might be mixed into a threaded engagement portion between the nut and the head. 
     SUMMARY OF INVENTION 
     The present invention to provide a filter device capable of preventing water or foreign matter entering a threaded engagement portion. 
     In one or more embodiments of the present invention, a filter device according to the present invention includes, for example, a head including an inflow port and an outflow port; a filter element assembly including a casing having a substantially bottomed cylindrical shape, a first screw part formed on an inner circumferential face or an outer circumferential face of the casing and formed in a vicinity of an opening end of the casing, and a filter element provided inside the casing; and a substantially disc-shaped elastic member formed of an elastically deformable material, wherein a second screw part threadedly engaged with the first screw part is formed in the head, a recessed part disposed adjacently with the first screw part is formed on a face on which the first screw part is formed in the casing, the elastic member is provided in the recessed part, and when the first screw part and the second screw part are threadedly engaged, the filter element assembly is attached to the head, and the elastic member deforms along a convex-concave shape of the second screw part and seals gap between the casing and the head. 
     Due to the above features, when the first screw part formed in the vicinity of the opening end of the casing is threadedly engaged with the second screw part formed on the head, the filter element assembly is attached to the head, and the elastic member provided on the face on which the first screw part is formed in the casing deforms along the convex-concave shape of the second screw part. This allows the gap between the casing and the head to be sealed, and water or foreign matter can be prevented from entering the threaded engagement portion (the first screw part and the second screw part). 
     Herein, the recessed part is formed in such a manner as to cut out part of a leading end face substantially orthogonal to the inner circumferential face or the outer circumferential face of the casing, and when the filter element assembly is attached to the head, the elastic member may seal gap between the leading end face and the head. Thus, the gap between the casing and the head can be sealed in plural directions, and water or foreign matter can be securely prevented from being mixed into the threaded engagement portion. 
     Herein, the elastic member may have a substantially U-shaped cross section and be provided in the casing in such a manner as to cover the leading end face. Thus, the gap between the casing and the head can be sealed with a plurality of directions, and water or foreign matter can be securely prevented from being mixed into the threaded engagement portion. In addition, the elastic member is provided in the casing so as to cover the leading end face, hence the elastic member can be easily attached to the filter element assembly, and the filter element assembly can be easily attached to the head. 
     According to one or more embodiments of the present invention, water or foreign matter can be prevented from entering the threaded engagement portion. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross sectional view illustrating the overview of a filter device  1  of an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view illustrating the overview of the filter device  1  of which a part is enlarged and displayed. 
         FIG. 3  is a cross-sectional view illustrating the overview of a filter element assembly  20 . 
         FIG. 4  is a cross-sectional view illustrating the overview of a filter device  2  of which a part is enlarged and displayed. 
         FIG. 5  is a cross-sectional view illustrating the overview of a filter device  3  of which a part is enlarged and displayed. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Detailed description of embodiments of the present invention will be given with reference to drawings below. 
     First Embodiment 
       FIG. 1  is a cross-sectional view illustrating the overview of a filter device  1  of a first embodiment of the present invention.  FIG. 2  is a cross-sectional view illustrating the overview of the filter device  1  of which a part is enlarged and displayed.  FIG. 3  is a cross-sectional view illustrating the overview of a filter element assembly  20 . Note that, in  FIGS. 1 to 3 , hatching which indicates a cross section is partially omitted. 
     The filter device  1  mainly includes a head  10  and the filter element assembly  20 . 
     The head  10  is a member having a substantially bottomed cylindrical shape and formed of metal. The head  10  includes an inflow port and an outflow port. Hereinafter, the detail of the head  10  will be described with reference to  FIG. 2 . 
     An attachment part  10   a  having a substantially cylindrical shape and formed in such a manner as to protrude from a bottom face to a lower side (−z side) is formed on a side face of the head  10 . A male screw part  10   b  is formed on the outer circumferential face of the attachment part  10   a.    
     The head  10  includes a fitting cylinder  10   c  having a substantially cylindrical shape and formed in such a manner as to protrude from the bottom face to the lower side (−z side) on the inner side of the attachment part  10   a.  The fitting cylinder  10   c  is inserted into cylindrical parts  35   a  and  36   a  (described later) of plates  35  and  36 . A plane  10   d  abutted with a filter element  30  is formed on the outer circumference of the fitting cylinder  10   c.    
     In the head  10 , an inflow part  10   e  that allows hydraulic oil to flow into the inside of the filter device  1  and an outflow part  10   f  that allows the hydraulic oil to flow out to the outside of the filter device  1  are formed. 
     A valve  11  is provided on a wall face between the inflow part  10   e  and the outflow part  10   f  on the bottom face of the head  10 . The valve  11  opens and closes in accordance with a difference between pressure inside the inflow part  10   e  and pressure inside the outflow part  10   f.  Known techniques can be applied to the valve  11 , and thus the detailed description thereof will be omitted. 
     The description will now return to  FIG. 1 . The filter element assembly  20  mainly includes a casing  21 , a press ring  25 , and the filter element  30 . Hereinafter, the filter element assembly  20  will be described with reference to  FIG. 3 . 
     The casing  21  is a substantially bottomed cylindrical member formed of metal, one end of which is substantially closed, the other end of which is opened. The casing  21  includes a casing main body  22  having a substantially bottomed cylindrical shape and a cover  23  having a substantially cylindrical shape. 
     The filter element  30  is provided inside the casing main body  22 . In addition, a spring  24 , one end of which is abutted with the bottom face of the casing main body  22 , the other end of which is abutted with the filter element  30 , is provided inside the casing main body  22 . 
     The cover  23  is provided in the vicinity of an opening end of the casing main body  22 . The inner circumferential face of the cover  23  is fitted with the outer circumferential face of the casing main body  22 , which allows the casing main body  22  and the cover  23  to be integrated. 
     An elastic member (e.g., an O-ring)  41  is provided between the outer circumferential face of the casing main body  22  and the inner circumferential face of the cover  23 , and gap between the casing main body  22  and the cover  23  is sealed by the elastic member  41 . 
     A female screw part  23   a  is formed on the inner circumferential face of the cover  23 . The female screw part  23   a  is formed in the vicinity of an opening end of the cover  23  (that is, the casing  21 ). When the female screw part  23   a  is threadedly engaged with the male screw part  10   b,  the casing  21  is attached to the head  10 . 
     A recessed part  23   b  is formed on the inner circumferential face (face in which the female screw part  23   a  is formed) of the cover  23 . The recessed part  23   b  and the female screw part  23   a  are adjacently disposed. Note that, preferably, the recessed part  23   b  is provided in the vicinity of a leading end on a side where the cover  23  is not abutted with the casing main body  22 . An elastic member  45  (see  FIGS. 1 and 2 ) is provided in the recessed part  23   b.  The elastic member  45  is a substantially disc-shaped member formed of an elastically deformable material. 
     The press ring  25  is provided on the inner side of the casing  21  (the casing main body  22  and the cover  23 ). The press ring  25  is a substantially circular plate-shaped member including a hole formed in the center thereof. 
     A male screw part  25   a  is formed on the outer circumferential face of the press ring  25 . When the male screw part  25   a  is threadedly engaged with the female screw part  23   a,  the press ring  25  is attached to the casing  21 , thereby forming the filter element assembly  20 . 
     An elastic member (e.g., an O-ring)  42  is provided between the outer circumferential face of the press ring  25  and the inner circumferential face of the casing main body  22 , and gap between the casing main body  22  and the press ring  25  is sealed by the elastic member  42 . 
     A recessed part  25   c  is formed on an upper end face  25   b  of the press ring  25 . An elastic member (e.g., an O-ring)  43  is provided in the recessed part  25   c.    
     After the spring  24  and the filter element  30  are inserted into the casing  21 , the press ring  25  is attached to the casing  21 . The filter element is pressed upward (+z direction) by the energizing force of the spring  24 , and thus the filter element  30  is abutted with a plane part  25   d  formed on the lower end face of the press ring  25 . 
     The filter element  30  mainly includes an inner tube  31 , a filtration member  32 , and plates  34 ,  35  and  36  provided on the inner tube  31 , the filtration member  32 , and both ends of the filtration member  32 . 
     The inner tube  31  is a member having a substantially hollow cylindrical shape and formed of a material with high corrosion resistance (resin in the present embodiment). Multiple holes  31   a  through which the hydraulic oil passes are formed on the entire face of the inner tube  31 . 
     The filtration member  32  has a substantially hollow cylindrical shape having a thickness in the radial direction thereof. The filtration material  32  is formed by pleating sheet-like filter paper using synthetic resin, paper, or the like, and connecting both ends of the pleated filter paper to form a cylindrical shape. The filtration material  32  is provided on the outer side of the inner tube  31 . 
     The plate  34  is provided at one ends (lower ends) of the inner tube  31  and the filtration material  32 , and the plate  35  is provided at the other ends (upper ends). The plate  34  and the plate  35  are substantially bottomed cylindrical members, and are formed using a material with high corrosion resistance. 
     A recessed part  34   a  is formed in the center of the plate  34 . The spring  24  is abutted on (−z) side of the recessed part  34   a.    
     The plate  36  is provided on the upper (+z) side of the plate  35 . The cylindrical parts  35   a  and  36   a  having a substantially cylindrical shape are provided in the center of the plates  35  and  36 , respectively. A convex face  36   c  is formed on the upper face  36   b  of the plate  36  in such a manner to surround the cylindrical part  36   a.    
     Next, the assembling of the filter device  1  configured as described above will be described with reference to  FIG. 2 . The female screw part  23   a  formed in the cover  23  is threadedly engaged with the male screw part  10   b  formed on the head  10 , so that the casing  21  is attached to the head  10 . 
     Since the elastic member  45  is provided in the recessed part  23   b  formed in the cover  23 , when the casing  21  is attached to the head  10 , the elastic member  45  deforms along the convex-concave shape of the male screw part  10   b.  As a result, gap between the casing  21  and the head  10  is sealed by the elastic member  45 . 
     In addition, when the casing  21  is attached to the head  10 , the fitting cylinder  10   c  is inserted into the cylindrical parts  35   a  and  36   a  of the plates  35  and  36 , and the plane  10   d  presses the convex face  36   c  in the (−z) direction. As a result, the filter element  30  is positioned inside the casing  21 . In addition, gap between the head  10  and the press ring  25  (that is, the filter element assembly  20 ) is sealed by the elastic member  43  provided in the recessed part  25   c.    
     Next, the filtration function of the filter device  1  will be described with reference to  FIG. 1 . The arrows in  FIG. 1  indicate the flow of the hydraulic oil inside the filter device  1 . 
     Hydraulic oil L 1  to be filtered, among the hydraulic oil, passes through the inflow part  10   e  and flows into a space S 1 . The hydraulic oil L 1  that has flown into the space S 1 , flows into a space S 2  between the casing  21  and the filter element  30 . 
     Subsequently, the hydraulic oil L 1  sequentially passes the filtration member  32  and the inner tube  31  and flows into a space S 3 , which is the internal space of the inner tube  31 . The hydraulic oil L 1  is filtered by the filtration member  32 . Filtered hydraulic oil L 2  that has flown into the space S 3  passes through a space S 4  and the outflow part  10   f  and is discharged out of the filter device  1 . 
     In a case where the filter device  1  is continuously used, dust adheres to the filtration member  32 , which increases a difference in pressure between the space S 1  and the space S 4 . In a case where a difference in pressure between the space S 1  and the space S 4  is equal to or higher than a certain threshold value (threshold value can be set to a freely selected value), the valve  11  opens, and the hydraulic oil L 1  is discharged to the space S 4 . 
     According to the present embodiment, the elastic member  45  deforms along the convex-concave shape of the male screw part  10   b,  and gap between the male screw part  10   b  and the cover  23  is sealed. Thus, water or foreign matter can be prevented from entering the male screw part  10   b  and the female screw part  23   a  (hereinafter referred to as “threaded engagement portion”). 
     Even when the elastic member  45  is not provided, the elastic member  42  is provided between the outer circumferential face of the press ring  25  and the inner circumferential face of the casing main body  22 , water or foreign matter is prevented from entering into the casing  21 , and oil is prevented from leaking out of the casing  21 . However, when water enters the threaded engagement portion, an area on the outer side of the elastic member  42  (see two-dot chain lines in  FIG. 2 ) might rust. When the formation of rust occurs, not only the male screw part  10   b,  the female screw part  23   a,  or the male screw part  25   a  but also surfaces including the inner circumferential face of the casing main body  22  and the outer circumferential face of the press ring  25  are corroded and become coarse. 
     In a state where the filter element assembly  20  is attached to the head  10 , the internal pressure of the casing  21  increases. Thus, when the area on the outside with respect to the elastic member  42  rusts, and the elastic member  42  receives pressure and moves to the outside, the deformation amount of the elastic member  42  is reduced, which might reduce sealing performance, and cause the oil to leak from the inside to the outside. In addition, when foreign matter is mixed into the threaded engagement portion, and threaded engagement is released, the surface of the male screw part  10   b  or the female screw part  23   a  might be damaged. 
     In contrast, in the present embodiment, water or foreign matter is prevented from entering the threaded engagement portion, trouble such as leakage of oil can be prevented. 
     Note that, in the present embodiment, the female screw part  23   a  is formed on the inner circumferential face of the cover  23 , and the male screw part  10   b  is formed on the outer circumferential face of the attachment part  10   a,  but the male screw part may be formed on the outer circumferential face of the cover  23 , and the female screw part may be formed on the inner circumferential face of the attachment part  10   a.  In this case, a recessed part for providing the elastic member is only required to be formed on the outer circumferential face of the cover  23  while being disposed adjacently to the male screw part. 
     Second Embodiment 
     In the first embodiment of the present invention, the elastic member  45  is provided in the recessed part  23   b  formed on the inner circumferential face of the cover  23  to seal the threaded engagement portion, but a method of sealing the threaded engagement portion is not limited to this. 
     In a second embodiment of the present invention, gap between the leading end face of the casing and the head is sealed by an elastic member, in addition to the threaded engagement portion between the casing and the head. Hereinafter, a filter device  2  according to the second embodiment of the present invention will be described. A difference between the filter device  1  and the filter device  2  is only a cover and an elastic member, and thus a cover  23 A and an elastic member  46  of the filter device  2  will be described. The same sign is applied to the same part as the first embodiment, and the description of the same part will be omitted. 
       FIG. 4  is a cross-sectional view illustrating the overview of the filter device  2  of which a part is enlarged and displayed. The filter device  2  mainly includes the head  10  and a filter element assembly  20 A. The filter element assembly  20 A mainly includes a casing  21 A, the press ring  25 , and the filter element  30 . The casing  21 A includes the casing main body  22  and a cover  23 A having a substantially cylindrical shape. 
     Only a difference between the cover  23 A and the cover  23  lies in the position of a recessed part. A recessed part  23   d  is formed in the cover  23 A in such a manner as to cut out part of a leading end face  23   c  substantially orthogonal to the inner circumferential face or the outer circumferential face of the cover  23 A (that is, the casing  21 A). 
     An elastic member  46  is provided in the recessed part  23   d.  The elastic member  46  is a substantially disc-shaped member formed of an elastically deformable material. 
     When the female screw part  23   a  formed in the cover  23 A is threadedly engaged with the male screw part  10   b  formed on the head  10 , and the casing  21 A is attached to the head  10 , the inner circumferential part of the elastic member  46  deforms along the convex-concave shape of the male screw part  10   b.  As a result, gap between the inner circumferential face of the casing  21 A and the outer circumferential face of the head  10  is sealed by the elastic member  46 . 
     Further, when the casing  21 A is attached to the head  10 , the elastic member  46  deforms in the thickness direction thereof (z direction). As a result, gap between the leading end face  23   c  of the casing  21  and the head  10  is sealed by the elastic member  46 . 
     According to the present embodiment, the gap between the casing  21 A and the head  10  is sealed with a plurality of directions, so that water or foreign matter can be securely prevented from being mixed into the threaded engagement portion. 
     Third Embodiment 
     Similar to the second embodiment, in a third embodiment of the present invention, gap between the leading end face of the casing and the head is sealed by an elastic member, in addition to the threaded engagement portion between the casing and the head. Hereinafter, a filter device  3  according to the third embodiment of the present invention will be described. A difference between the filter device  1  and the filter device  3  lies in only a cover and an elastic member, and thus a cover  23 B and an elastic member  47  of the filter device  3  will be described hereinafter. The same sign is applied to the same part as the first embodiment, and the description of the same part will be omitted. 
       FIG. 5  is a cross-sectional view illustrating the overview of the filter device  3  of which a part is enlarged and displayed. The filter device  3  mainly includes the head  10  and a filter element assembly  20 B. The filter element assembly  20 B mainly includes a casing  21 B, the press ring  25 , and the filter element  30 . The casing  21 B includes the casing main body  22  and a cover  23 B having a substantially cylindrical shape. 
     Only a difference between the cover  23 B and the cover  23  lies in the position of a recessed part. A recessed part  23   e  is formed in the cover  23 B in such a manner as to cut out part of the leading end face  23   c  substantially orthogonal to the inner circumferential face or the outer circumferential face of the cover  23 B (that is, the casing  21 B). 
     The elastic member  47  is a substantially disc-shaped member formed of an elastically deformable material. The elastic member  47  has a substantially U-shaped cross section and is provided in the cover  23 B so as to cover the leading end face  23   c  and the recessed part  23   e.    
     When the female screw part  23   a  formed in the cover  23 B is threadedly engaged with the male screw part  10   b  formed on the head  10 , and the casing  21 B is attached to the head  10 , the inner circumferential part of the elastic member  47  deforms along the convex-concave shape of the male screw part  10   b.  As a result, gap between the inner circumferential face of the casing  21 B and the outer circumferential face of the head  10  is sealed by the elastic member  47 . 
     Further, when the casing  21 B is attached to the head  10 , the elastic member  47  covers gap between the leading end face  23   c  of the casing  21  and the head  10 . As a result, the gap between the leading end face  23   c  of the casing  21  and the head  10  is sealed by the elastic member  47 . 
     According to the present embodiment, the gap between the casing  21 B and the head  10  is sealed with a plurality of directions, so that water or foreign matter can be securely prevented from being mixed into the threaded engagement portion. In addition, the elastic member  47  is provided in the cover  23 B so as to cover the leading end face  23   c  and the recessed part  23   e,  and thus the elastic member  47  is easily attached to the filter element assembly  20 B, and the filter element assembly  20 B is easily attached to the head  10 . 
     Embodiments of the invention have been described in detail with reference to the drawings. However, specific configurations are not limited to the embodiments, and changes in the design or the like are also included within a scope not departing from the gist of the invention. For example, the above examples have been explained in detail in order to facilitate understanding of the present invention and are not necessarily limited to examples provided with the entirety of the configuration described above. In addition, the configuration of an embodiment may be partially replaced with the configuration of a different embodiment, or the configuration of the different embodiment may be added to, deleted from, or replaced with the configuration of the embodiment. 
     Further, the term “substantially” in the present invention is not to be understood as merely being strictly the same, and is a concept that includes variations and modifications to an extent that does not result in loss in identity. For example, a term “substantially cylindrical shape” is not strictly limited to a cylindrical shape. Further, for example, when a term “substantially center” is simply expressed, the term includes not only the strict center but also an approximately center. Furthermore, the meaning of the term “vicinity” in the present invention includes a range of regions (which can be determined as desired) near a position serving as a reference. For example, a term “a vicinity of an opening end” refers to a range of regions near the opening end, and is a concept indicating that the opening end may or may not be included. 
     REFERENCE SIGNS LIST 
     
         
           1 ,  2 ,  3  Filter device 
           10  Head 
           10   a  Attachment part 
           10   b  Male screw part 
           10   c  Fitting cylinder 
           10   d  Plane 
           10   e  Inflow part 
           10   f  Outflow part 
           11  Valve 
           20 ,  20 A,  20 B Filter element assembly 
           21 ,  21 A,  21 B Casing 
           22  Casing main body 
           23 ,  23 A,  23 B Cover 
           23   a  Female screw part 
           23   b,    23   d,    23   e  Recessed part 
           23   c  Leading end face 
           24  Spring 
           25  Press ring 
           25   a  Male screw part 
           25   b  Upper end face 
           25   c  Recessed part 
           25   d  Plane part 
           30  Filter element 
           31  Inner tube 
           31   a  Hole 
           32  Filtration member 
           34 ,  35 ,  36  Plate 
           34   a  Recessed part 
           35   a,    36   a  Cylindrical part 
           36   b  Upper face 
           36   c  Convex face 
           41 ,  42 ,  43 ,  44 ,  45 ,  46 ,  47  Elastic member