JP2011047396A - Oil filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate attachment/detachment of an oil filter to an engine and replacement of filter elements. <P>SOLUTION: The oil filter includes: a bottomed-tubular casing 2; a central tubular part 3 disposed at the central part thereof and axially extended; and the tubular filter element 5 housed in an element housing chamber 4 demarcated between the central tubular part and the casing. The central tubular part is formed to be projected from an inner face of a bottom wall 12 of the casing to an opening part 8 side of the casing, and a tip part 9 thereof is detachably connected to an engine body 11. The filter element is fitted onto the central tubular part from the tip part of the central tubular part, and is fixed to the central tubular part with a slip-off preventive member 13 detachably engaged with the tip part of the central tubular part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an oil filter which is detachably attached to an automobile engine and filters oil for lubrication and cooling.

  An automobile engine is provided with an oil filter that filters oil used for lubrication and cooling to remove foreign substances in the oil. In this type of oil filter, a filter element having a thick cylindrical shape with a large number of folds formed by folding the filter paper in the circumferential direction is housed in a casing having a bottomed cylindrical shape, and unfiltered oil is collected. A configuration in which filtered oil is recovered from the inside of the filter element by flowing into the filter element from the outside is widely used.

  In addition, this type of oil filter has a structure that can be detachably attached to the engine because it is necessary to replace the oil filter when the filtering function is reduced due to clogging of the filter element due to aging. For example, a structure in which the casing is divided into two and one of them is formed on the engine side, a structure in which a center bolt that penetrates the center portion of the casing is screwed into the engine side (bolt-on type), There is known a structure (spin-on type) in which a member in which a female thread is formed is provided and attached to an engine by rotating a casing (see Patent Documents 1 to 3).

JP 2007-291939 A JP 2004-251185 A Japanese Patent Laid-Open No. 2005-171985

  However, in the case of an oil filter having a structure in which the casing is divided into two parts, it is necessary to remove the filter element from the engine side or attach it to the engine side separately from the casing when replacing the oil filter. There was a problem that workability at the time of removal was poor.

  Also, with the bolt-on type oil filter described above, when the center bolt is removed, high-temperature oil leaks from the insertion hole, so it is necessary to proceed carefully so as not to cause burns. There was a problem that workability of was bad.

  Further, in the above spin-on type oil filter, the member on which the female screw is formed is provided so as to cover the open part of the casing. Therefore, if the member on which the female screw is formed is not removed from the casing, the filter Since the element could not be taken out, there was a problem that it was difficult to replace the filter element.

  The present invention has been devised to solve such problems of the prior art, and its main purpose is to facilitate the work of mounting / removing the engine and the replacement of the filter element. The object is to provide a configured oil filter.

  A first invention made to solve the above problems is a casing (2.102) having a bottomed cylindrical shape, and a central cylindrical portion provided in an axially extending manner at the central portion of the casing. (3 · 103) and a tubular filter element (5) housed in an element housing chamber (4 · 104) defined between the central tubular portion and the casing, A filtered oil circulation hole is formed in such a manner that the oil recovery path (6, 106) defined in the inner peripheral wall of the central cylindrical portion communicates with the secondary side (4b, 104b) of the element storage chamber. (7 · 107) is an oil filter (1 · 101), in which the central cylindrical portion extends from the inner surface of the bottom wall (12 · 112) of the casing to the open portion (8 · 108) of the casing. Provided in a manner protruding toward the side, And the filter element is externally fitted to the central cylindrical portion from the distal end portion of the central cylindrical portion, and the filter element is fitted to the central cylindrical portion. It is set as the structure fixed with respect to the said center cylindrical part with the retaining member (13) which detachably engages with the front-end | tip part of a center cylindrical part.

  According to this, since the filter element is integrally held in the casing via the central cylindrical portion, the attachment / detachment work with respect to the engine body is facilitated. In addition, by removing the retaining member from the central cylindrical portion, the filter element can be removed from the central cylindrical portion, and the replacement work of the filter element is facilitated.

  According to a second aspect of the present invention, there is provided a bypass passage that communicates the primary side (4a / 104a) and the secondary side (4b / 104b) of the element accommodating chamber in the first aspect. And a relief valve (22) that opens and closes (21, 121), the relief valve being defined on the bottom wall side of the casing from the oil recovery path inside the central cylindrical portion. It is set as the structure accommodated in (23 * 123).

  According to this, it is possible to prevent the filter element from being damaged due to an excessive pressure difference between the primary side and the secondary side of the element storage chamber due to clogging of the filter element. In addition, since the relief valve is housed inside the central cylindrical portion, the relief valve does not interfere with the removal or attachment of the filter element, so that the removal or attachment of the filter element is facilitated.

  According to a third aspect of the present invention for solving the above-described problems, in the second aspect of the present invention, the bypass passage is configured such that the oil on the primary side of the element accommodating chamber is guided to the valve accommodating chamber. Unfiltered oil established in the peripheral wall of the central cylindrical portion in a mode in which the primary side passage (24, 124) provided on the wall side communicates with the secondary side of the valve storage chamber and the element storage chamber The relief valve is configured by a valve body (26) provided to open and close the unfiltered oil circulation hole by moving back and forth in the valve housing chamber in the axial direction. And a spring (27) for urging the valve body toward the fully closed position.

  According to this, since the peripheral wall of the central cylindrical part can be used also as the housing of the relief valve, the size can be reduced and the manufacturing cost can be reduced.

  According to a fourth aspect of the present invention for solving the above-described problems, in the first to third aspects of the invention, the casing includes a connecting convex portion (17) protruding in an axial direction from an inner surface of a bottom wall of the casing. The central cylindrical portion is molded separately from the casing in advance and fixed to the bottom wall of the casing in a form in which the connecting convex portion is fitted into the base end portion (18) on the bottom wall side of the casing. The configuration is as follows.

  According to this, since the central cylindrical part and the casing are previously formed separately and assembled together, the manufacture becomes easy. And since a connection convex part is inserted and fixed to the base end part of a center cylindrical part, a center cylindrical part can be fixed to a casing with high support rigidity.

  Furthermore, before assembling the central tubular portion and the casing, the relief valve can be assembled to the central tubular portion by inserting the relief valve from the opening of the base end portion on the bottom wall side of the casing in the central tubular portion. Can be assembled easily.

  According to a fifth aspect of the present invention for solving the above-described problems, in the fourth aspect, the primary side passage is formed in a radial direction on an end surface of the central cylindrical portion that contacts the bottom wall of the casing. A radial groove (31), a circumferential groove (32) formed circumferentially on the inner peripheral side of the end surface of the central cylindrical portion, and an axis formed axially on the outer peripheral surface of the connecting convex portion The directional groove (33) is formed, and the radial groove and the axial groove are communicated with each other through the circumferential groove.

  According to this, the primary side passage can be provided while maintaining the joining rigidity between the central cylindrical portion and the connecting convex portion of the casing without increasing the thickness. In addition, since the radial groove and the axial groove communicate with each other via the circumferential groove, it is troublesome to adjust the relative angle between the central cylindrical portion and the connecting convex portion so that the radial groove and the axial groove are aligned. Disappears.

  A sixth invention made to solve the above-mentioned problems is that, in the fourth and fifth inventions, the valve body is regulated in a manner protruding in the axial direction on the top surface (29) of the connecting convex portion. A protrusion (35) is formed, and the top surface of the connecting convex portion and the front surface of the valve body are always kept in a state of being separated from each other.

  According to this, when the valve body is opened from the fully closed position by the pressure of oil introduced to the front surface side of the valve body through the primary side passage, the pressure receiving area on which the oil pressure acts on the valve body increases. The relief valve can be opened quickly.

  A seventh invention made to solve the above-mentioned problems is that, in the fourth and fifth inventions, a concave portion (51) is formed on the top surface of the connecting convex portion in a form communicating with the primary-side passage. The formed structure is assumed.

  According to this, when the valve body is opened from the fully closed position by the pressure of oil introduced to the front surface side of the valve body through the primary side passage, the pressure receiving area on which the oil pressure acts on the valve body increases. The relief valve can be opened quickly.

  An eighth invention made to solve the above-mentioned problems is that, in the first to seventh inventions, the base end portion (18) on the bottom wall side of the casing in the central cylindrical portion faces radially outward. A flange (19) extending in the direction is formed, and the filter element is fixed to the central cylindrical portion in a mode of being sandwiched between the flange and the retaining member.

  According to this, the filter element can be securely fixed to the central cylindrical portion, and it is not necessary to apply a large load to the bottom wall of the casing for fixing the filter element. Can be avoided. In addition, the filter element is in close contact with the flange of the central cylindrical portion on one end side, and the filter element is in close contact with the retaining member on the other end side, thereby reliably partitioning the primary side and the secondary side of the element storage chamber. be able to.

  A ninth invention made to solve the above-mentioned problems is that, in the first to third inventions, the central cylindrical portion (103) is molded separately from the casing (102) in advance, A connecting cylindrical portion (117) for connecting the central cylindrical portion to the bottom wall (112) of the casing is molded separately from the casing in advance and fixed to the bottom wall of the casing, and the central cylindrical portion However, it is set as the structure fixed with respect to the bottom wall of the said casing through the connection cylindrical part in the aspect which fitted the base end part (118) by the side of the bottom wall of the said casing to the said connection cylindrical part. .

  According to this, since the central cylindrical part and the casing are previously formed separately and assembled together, the manufacture becomes easy. Furthermore, since the connecting cylindrical portion for fixing the central cylindrical portion to the casing is a separate member from the casing, the manufacturing is further facilitated. And since the base end part of a center cylindrical part is fitted and fixed to a connection cylindrical part, a center cylindrical part can be fixed to a casing with high support rigidity.

  According to a tenth aspect of the present invention for solving the above-mentioned problems, in the ninth aspect of the present invention, a concave portion (133) is formed radially on the inner surface side of the bottom wall of the casing, and A flange (119) extending outward in the radial direction is formed on the bottom wall side of the casing, and the flange is joined to a convex portion (134) provided between the concave portions in the bottom wall so as to form the connecting cylindrical shape. A portion is fixed to the bottom wall of the casing, and an open portion (135a) on the outer peripheral side of the empty space (135) defined between the recess of the bottom wall and the flange of the connecting cylindrical portion is accommodated in the element The primary side passage (124) is formed by communicating with the primary side (104a) of the chamber (104) and communicating the center side opening (135b) with the inside of the central cylindrical portion. .

  According to this, it is possible to provide the primary side passage by processing the concave and convex portions only on the bottom wall side of the casing, the end surface of the connecting cylindrical portion is flat, and it is necessary to apply special processing to the connecting cylindrical portion. Therefore, it is possible to reduce the dimension of the connecting cylindrical portion, particularly the thickness of the flange joined to the bottom wall of the casing.

  Furthermore, since the connecting cylindrical portion and the bottom wall of the casing can be brought into contact with each other with a large area by the flange of the connecting cylindrical portion, the connecting cylindrical portion is firmly fixed to the bottom wall of the casing, The support rigidity of the connection cylindrical part which supports a center cylindrical part can be improved.

  An eleventh invention made to solve the above-mentioned problems is that, in the ninth and tenth inventions, a flange extending radially outward is formed on the bottom wall side of the casing in the connecting cylindrical portion. The filter element is configured to be fixed to the central cylindrical portion in a mode of being sandwiched between a flange of the connecting cylindrical portion and the retaining member.

  According to this, the filter element can be securely fixed to the central cylindrical portion, and it is not necessary to apply a large load to the bottom wall of the casing for fixing the filter element. In addition, the filter element is in close contact with the flange of the central cylindrical portion on one end side, and the filter element is in close contact with the retaining member on the other end side, thereby reliably partitioning the primary side and the secondary side of the element storage chamber. be able to.

  In a twelfth aspect of the invention made to solve the above-mentioned problems, in the first to eleventh aspects of the invention, the filter element has a plurality of folds (41) formed by folding the filtration sheet material in the circumferential direction as a whole. A thick cylindrical shape is held in a cylindrical holder (43) inserted in the center thereof, and the fold portion is inclined in the radial direction in the element case (44). Contained configuration.

  According to this, the element case covers the outer peripheral side of the filter element, so that the fold portion of the filter element is held in an inclined state with respect to the radial direction, and the surface area (filtration area) of the filter element per unit volume increases. Therefore, it is possible to improve the filtration function and save space.

  A thirteenth invention made to solve the above-mentioned problem is that, in the twelfth invention, the element case includes a peripheral wall (46) partially covering the outer peripheral side of the filter element, and the central cylindrical portion. A bottomed cylindrical shape including a bottom wall (47) having a center hole (48) to be inserted is formed, and the portion of the filter element not covered by the peripheral wall is positioned on the bottom wall side of the casing. It is set as the structure provided in.

  According to this, since the oil introduced from the open part side of the casing enters the filter element from the bottom wall side opposite to the open part of the casing, it is possible to ensure a long distance for the oil to pass through the filter element, Thereby, filtration efficiency can be improved.

  And since the part by the side of the open part of the casing in a filter element is covered with an element case, the backflow of oil can be suppressed and a non-return valve can be abolished. For this reason, it is possible to reduce the manufacturing cost, and moreover, since the check valve generally formed of a rubber material is eliminated, the reuse becomes easy. In addition, since there is no check valve, the cleaning liquid can be circulated in the backflow direction in the oil filter, whereby the filter element can be cleaned without disassembling the oil filter.

  As described above, according to the present invention, since the filter element is integrally held in the casing via the central cylindrical portion, the attachment / removal work with respect to the engine body is facilitated. In addition, by removing the retaining member from the central cylindrical portion, the filter element can be removed from the central cylindrical portion, and the replacement work of the filter element is facilitated.

It is sectional drawing which shows the oil filter which concerns on the 1st Embodiment of this invention. It is a figure which shows the attachment condition of the oil filter shown in FIG. It is a figure which shows the assembly condition of the oil filter shown in FIG. It is a figure which shows the assembly condition of the oil filter shown in FIG. It is sectional drawing which shows the fully open state of the relief valve in the oil filter shown in FIG. It is a perspective view which shows the primary side channel | path shown in FIG. It is a perspective view which shows the connection convex part shown in FIG. It is principal part sectional drawing which shows the filter element shown in FIG. It is a perspective view which shows another example of the connection convex part shown in FIG. It is sectional drawing which shows the oil filter which concerns on the 2nd Embodiment of this invention. It is a figure which shows the assembly condition of the oil filter shown in FIG. It is sectional drawing which shows the fully open state of the relief valve in the oil filter shown in FIG. It is a perspective view which shows the bottom wall and connection cylindrical part of a casing shown in FIG. 10, (A) shows the state before an assembly | attachment, (B) shows the state after an assembly | attachment, respectively. It is sectional drawing cut | disconnected by the XIV-XIV line | wire shown in FIG. It is sectional drawing cut | disconnected by the XV-XV line | wire shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
As shown in FIG. 1, an oil filter 1 according to a first embodiment of the present invention is provided with a casing 2 having a bottomed cylindrical shape and an axially extending manner at the center of the casing 2. A central cylindrical portion 3 and a cylindrical filter element 5 accommodated in an element accommodating chamber 4 defined between the central cylindrical portion 3 and the casing 2 are provided.

  The peripheral wall of the central cylindrical portion 3 has a filtered oil circulation hole 7 in a mode in which the oil recovery path 6 defined therein and the secondary side (clean side) 4b of the element storage chamber 4 communicate with each other. Unfiltered oil is introduced from the opening 8 of the casing 2 to the primary side (dust side) 4a of the element storage chamber 4 and passes through the filter element 5 and the filtered oil circulation hole 7 to recover the oil. The filtered oil that has flowed into the path 6 is collected from the front end portion 9 on the open portion 8 side of the casing 2 in the central cylindrical portion 3.

  The central cylindrical portion 3 is provided in such a manner that it protrudes in the axial direction from the inner surface of the bottom wall 12 of the casing 2 toward the open portion 8 side of the casing 2, and its distal end portion 9 is detachable from the engine body 11. Connected to As shown in FIG. 2, a mounting cylinder 14 is fixed to the engine body 11 in advance, and a male screw formed on the mounting cylinder 14 is formed on the distal end portion 9 of the central cylindrical portion 3, so The oil filter 1 is attached to the engine body 11 by screwing together, and the operator rotates the casing 2 by holding the casing 2 with fingers or engaging an appropriate tool with the casing 2. Thus, the oil filter 1 can be attached and detached.

  The casing 2 is attached to the engine body 11 in such a manner that the opening 8 is closed by the mounting surface 11 a of the engine body 11, and the O-ring 16 fitted into the end 15 on the opening 8 side is the engine body 11. Sealing is performed in pressure contact with the mounting surface.

  As shown in FIG. 3, the filter element 5 is externally fitted to the central cylindrical portion 3 from the distal end portion 9 of the central cylindrical portion 3 and is detachably engaged with the distal end portion 9 of the central cylindrical portion 3. The retaining member 13 is fixed to the central cylindrical portion 3. In particular, here, the retaining member 13 is a nut that is screwed into a male screw formed at the distal end portion 9 of the central cylindrical portion 3. In addition, the thing of the structure which latches the filter element 5 elastically by engaging with the center cylindrical part 3 like a retaining ring etc. is also possible for a retaining member.

  As a result, the filter element 5 is integrally held in the casing 2 via the central cylindrical portion 3, so that attachment / detachment work with respect to the engine body 11 is facilitated. In addition, the filter element 5 can be removed from the central cylindrical portion 3 simply by removing the retaining member 13 from the central cylindrical portion 3, so that the filter element 5 can be easily replaced.

  As shown in FIG. 4, the casing 2 includes a connecting projection 17 that protrudes in the axial direction from the inner surface of the bottom wall 12, and the central cylindrical portion 3 is molded separately from the casing 2 in advance. It is fixed to the bottom wall 12 of the casing 2 in such a manner that the connecting projection 17 is fitted into the base end 18 on the bottom wall 12 side. In particular, here, since it is formed on the base end portion 18 of the central cylindrical portion with the male screw formed on the peripheral surface of the connecting convex portion 17, it is fixed by screwing the screw. Moreover, the outer periphery of the base end part 18 of the center cylindrical part 3 is formed in the hexagon so that it can tighten firmly with a tool (refer FIG. 6).

  In addition, an adhesive is applied to the contact surface between the base end portion 18 of the central cylindrical portion 3 and the connecting convex portion 17, and the base end portion 18 of the central cylindrical portion 3 and the connecting convex portion 17 are added to the screwing. It is good to bond and fix.

  As described above, since the central cylindrical portion 3 and the casing 2 are formed separately separately and assembled together, the manufacture becomes easy. And since the connection convex part 17 is inserted and fixed to the base end part 18 of the center cylindrical part 3, the center cylindrical part 3 can be fixed to the casing 2 with high support rigidity. The central cylindrical portion 3 can be integrally formed with the casing 2.

  As shown in FIG. 1, a flange 19 extending outward in the radial direction is formed at the base end 18 on the bottom wall 12 side of the casing 2 in the central cylindrical portion 3, and the filter element 5 is connected to the flange 19. And is fixed to the central cylindrical portion 3 in a state of being sandwiched between the retaining member 13.

  As a result, the filter element 5 can be reliably fixed to the central cylindrical portion 3, and it is not necessary to apply a large load to the bottom wall 12 of the casing 2 for fixing the filter element 5. The deformation of the bottom wall 12 of the casing 2 can be avoided. In addition, the filter element 5 is in close contact with the flange 19 of the central cylindrical portion 3 on one end side, and the filter element 5 is in close contact with the retaining member 13 on the other end side. The secondary side 4b can be reliably partitioned.

  Further, as shown in FIG. 1, the oil filter 1 has a relief valve 22 that opens and closes a bypass passage 21 that communicates the primary side 4a and the secondary side 4b of the element storage chamber 4. The valve 22 is accommodated in a valve accommodating chamber 23 defined on the bottom wall 12 side of the casing 2 from the oil recovery path 6 inside the central cylindrical portion 3.

  As a result, it is possible to prevent the filter element 5 from being damaged due to an excessive pressure difference between the primary side 4a and the secondary side 4b of the element storage chamber 4 due to clogging of the filter element 5 or the like.

  Further, as shown in FIG. 4, before assembling the central cylindrical portion 3 and the casing 2, the relief valve 22 is inserted from the opening of the base end portion 18 on the bottom wall 12 side of the casing 2 in the central cylindrical portion 3. By doing so, the relief valve 22 can be assembled to the central cylindrical portion 3, and the assembly becomes easy. In addition, since the relief valve 22 is housed inside the central cylindrical portion 3, the relief valve 22 does not interfere with the removal and attachment of the filter element 5, so that the removal and attachment of the filter element 5 is facilitated.

  As shown in FIG. 1, the bypass passage 21 includes a primary passage 24 provided on the bottom wall 12 side of the casing 2 so as to guide oil on the primary side 4 a of the element storage chamber 4 to the valve storage chamber 23. The valve housing chamber 23 and the secondary side 4b of the element housing chamber 4 are connected to each other with an unfiltered oil circulation hole 25 formed in the peripheral wall of the central cylindrical portion 3, and the relief valve 22 A valve body 26 is provided so as to open and close the unfiltered oil circulation hole 25 by moving back and forth in the storage chamber 23 in the axial direction, and a spring 27 that biases the valve body 26 toward the fully closed position. ing.

  Thereby, since the surrounding wall of the center cylindrical part 3 can be used also as the housing of the relief valve 22, size reduction can be achieved and manufacturing cost can be reduced.

  One end of the spring 27 abuts on the back surface of the valve body 26, and the other end abuts on the annular convex portion 28 extending inwardly from the peripheral wall of the central cylindrical portion 3, thereby connecting the valve body 26 to the convex projection. The valve body 26 is urged in the direction approaching the top surface 29 of the portion 17, and the valve body 26 is restricted by the connection convex portion 17 and is held at a fully closed position where the unfiltered oil circulation hole 25 is closed.

  The pressure on the primary side 4a of the element storage chamber 4 acts on the front surface of the valve body 26 via the primary passage 24, and the oil recovery path 6 and the valve storage chamber 23 are connected to the back surface of the valve body 26. By communicating, the pressure of the secondary side 4b of the element storage chamber 4 is acting.

  For this reason, the pressure difference between the primary side 4a and the secondary side 4b of the element accommodating chamber 4 becomes excessive due to clogging of the filter element 5 and the pressure on the primary side 4a acting on the front surface of the valve body 26 When the pressure on the secondary side 4b acting on the back surface of the body 26 is greater than the pressure applied by the spring 27, the valve body 26 is retracted and the unfiltered oil circulation hole 25 is opened as shown in FIG. After being opened, the oil on the primary side 4a of the element storage chamber 4 flows into the secondary side 4b of the element storage chamber 4 through the primary side passage 24 and the unfiltered oil circulation hole 25, and then for filtered oil. The oil flows into the oil recovery passage 6 through the circulation hole 7 and is recovered from the end portion 9 side of the central cylindrical portion 3.

  As shown in FIG. 6, the primary passage 24 includes a radial groove 31 formed in the radial direction on the end surface of the flange 19 that contacts the bottom wall 12 of the casing 2 at the proximal end portion 18 of the central cylindrical portion 3. The circumferential groove 32 formed in the circumferential direction on the inner peripheral side of the end surface of the flange 19 and the axial groove 33 formed in the axial direction on the outer peripheral surface of the connecting projection 17 are formed. The radial groove 31 and the axial groove 33 are communicated with each other. In particular, here, six radial grooves 31 and circumferential grooves on the central cylindrical portion 3 side are formed, and four axial grooves 33 on the connecting convex portion 17 side are formed.

  The radial groove 31 on the side of the central cylindrical portion 3 communicates with the inside and outside of the flange 19, and the circumferential groove 32 communicates with the open portion on the inner end side of the radial groove 31 to communicate with each other. After the oil on the primary side 4a circulates radially inward in the radial groove 31, it flows into the axial groove 33 on the connecting projection 17 side, and the radial groove 31 and the axial groove 33 are not aligned. In the part, oil flows from the radial groove 31 through the circumferential groove 32 into the axial groove 33. The axial groove 33 on the connecting convex portion 17 side is formed in a range from the vicinity of the inner surface of the bottom wall 12 of the casing 2 to the top surface 29 of the connecting convex portion 17 (see FIG. 7).

  Thereby, the primary side channel | path 24 can be provided, maintaining the joining rigidity of the center cylindrical part 3 and the connection convex part 17 of the casing 2, without increasing thickness. Moreover, since the radial groove 31 and the axial groove 33 are communicated with each other via the circumferential groove 32, the central cylindrical portion 3 and the connecting convex portion 17 so that the radial groove 31 and the axial groove 33 are aligned. There is no need to adjust the relative angle.

  In addition, as shown in FIG. 1, a protrusion 35 that restricts the valve body 26 of the relief valve 22 in a manner protruding in the axial direction is formed on the top surface 29 of the connecting convex portion 17, and the top surface of the connecting convex portion 17. 29 and the front surface of the valve body 26 are always kept in a separated state.

  Thereby, when the valve body 26 is opened from the fully closed position by the pressure of oil introduced to the front surface side of the valve body 26 through the primary side passage 24, the pressure receiving area where the oil pressure acts on the valve body 26 is increased. Therefore, the relief valve 22 can be opened quickly. When there is no protrusion 35 on the top surface 29 of the connecting convex portion 17 and the top surface 29 of the connecting convex portion 17 and the front surface of the valve body 26 are in full contact with each other, the peripheral surface of the connecting convex portion 17 is formed. Since the oil pressure acts on the valve body 26 only on the open surface of the axial groove 33 on the top surface 29 side, the pressure receiving area of the valve body 26 is small, and the responsiveness during the opening operation of the relief valve 22 is reduced. Absent.

  As shown in FIG. 8, the filter element 5 is a cylindrical holder in which a large number of pleats 41 formed by folding the filtration sheet material are arranged in the circumferential direction to form a thick cylindrical shape as a whole, and is fitted into the center portion thereof. 43 and is accommodated in the element case 44 with the fold 41 being inclined with respect to the radial direction. The holder 43 has a large number of holes 45 through which oil flows. The inclination angle θ with respect to the radial direction of the fold portion 41 of the filter element 5 is preferably about 60 °. The filter sheet material constituting the filter element 5 may be made of paper, but if a stainless steel mesh is used, cleaning becomes easy.

  Thereby, the element case 44 covers the outer peripheral side of the filter element 5, whereby the fold portion 41 is held in an inclined state with respect to the radial direction, and the surface area (filtration area) of the filter element 5 per unit volume increases. Therefore, it is possible to improve the filtration function and save space.

  As shown in FIG. 1, the element case 44 includes a peripheral wall 46 that partially covers the outer peripheral side of the filter element 5 and a bottom wall 47 in which a central hole 48 into which the central cylindrical portion 3 is inserted is opened. A portion of the filter element 5 that has a bottomed cylindrical shape and is not covered by the peripheral wall 46 outside the open portion 49 is provided on the bottom wall 12 side of the casing 2.

  Thereby, since the oil introduced from the open part 8 side of the casing 2 enters the filter element 5 from the bottom wall 12 side of the casing 2, it is possible to ensure a long distance for the oil to pass through the filter element 5, Thereby, filtration efficiency can be improved. Since the filtered oil circulation hole 7 in the central cylindrical portion 3 is located on the open part 8 side of the casing 2, the absence of the element case 44, the open part 8 side of the casing 2 from the filtered oil circulation hole 7. This is not desirable because the oil passes through the filter element 5 and the distance that the oil passes through the filter element 5 is shortened.

  And since the part by the side of the open part 8 of the casing 2 in the filter element 5 is covered with the element case 44, the backflow of oil can be suppressed and a check valve can be abolished. For this reason, it is possible to reduce the manufacturing cost, and moreover, since the check valve generally formed of a rubber material is eliminated, the reuse becomes easy. In addition, since there is no check valve, the cleaning liquid can be circulated in the back flow direction in the oil filter 1, and the filter element 5 can be cleaned without disassembling the oil filter 1.

  The element case 44 is fixed to the central cylindrical portion 3 together with the filter element 5 by the retaining member 13 by sandwiching the opening edge of the center hole 48 between the retaining member 13 and the holder 43. Further, as shown in FIG. 3, the element case 44 can be handled in an integrated state with the filter element 5 and the holder 43, so that disassembly and assembly are facilitated.

  A slit may be provided in the peripheral wall 46 and the bottom wall 47 of the element case 44. As a result, the oil passes through the portion of the filter element 5 on the side opposite to the opening 49 of the element case 44 across the filtered oil circulation hole 7, and the oil passes through the filter element 5 as a whole. Pass evenly. In particular, it is preferable to provide a slit so as to extend in the axial direction so as to rectify the oil.

  In the oil filter 1 configured as described above, all the components except the O-ring 16 can be made of metal. For example, the casing 2 can be manufactured by die-casting an aluminum alloy, the central cylindrical portion 3 can be manufactured by cutting carbon steel (for example, S45C), and the filter element 5 is manufactured by a stainless steel mesh. The valve body 26 of the relief valve 22 can be manufactured by drawing a steel plate (for example, SP), and the element case 44 can be manufactured by impact molding of an aluminum alloy. Thereby, reuse becomes easy and it can contribute to environmental protection.

  By the way, in the above example, in order to ensure a large pressure receiving area of the valve body 26 when the relief valve 22 is opened, as shown in FIG. 7, a configuration in which a projection 35 is formed on the top surface 29 of the connecting convex portion 17. However, as shown in FIG. 9, the top surface 29 of the connecting convex portion 17 may have a configuration in which the concave portion 51 is formed so as to communicate with the axial groove 33. Here, in particular, the recess 51 is formed in a groove shape in the radial direction. Even in such a configuration, the contact area between the connecting convex portion 17 and the valve body 26 in the fully closed position can be reduced, and a large pressure receiving area of the valve body 26 can be secured.

  In addition, by reducing the contact area between the connecting convex portion 17 and the valve body 26 in the fully closed position as described above, a large pressure receiving area of the valve body 26 can be secured. If the contact area with the body 26 is reduced, the stress acting on the valve body 26 at the time of the collision between the connecting convex portion 17 and the valve body 26 increases, so that the durability of the relief valve 22 may be reduced. For this reason, it is preferable to set the size of the protrusion 35 and the recess 51 in consideration of the material of the valve body 26 and the responsiveness of the relief valve 22 required.

<Second Embodiment>
As shown in FIG. 10, an oil filter 101 according to a second embodiment of the present invention is provided with a casing 102 having a bottomed cylindrical shape and a mode extending in the axial direction at the center of the casing 102. A central tubular portion 103 and a cylindrical filter element 5 housed in an element housing chamber 104 defined between the central tubular portion 103 and the casing 102 are provided.

  A filtered oil circulation hole 107 is formed in the peripheral wall of the central cylindrical portion 103 in such a manner that the oil recovery path 106 defined therein and the secondary side (clean side) 104b of the element storage chamber 104 communicate with each other. Unfiltered oil is introduced into the primary side (dust side) 104a of the element storage chamber 104 from the open portion 108 of the casing 102, passes through the filter element 5 and the filtered oil circulation hole 107, and recovers oil. The filtered oil that has flowed into the passage 106 is collected from the front end portion 109 of the central cylindrical portion 103 on the open portion 108 side of the casing 102.

  The central cylindrical portion 103 is provided in such a manner that it protrudes in the axial direction from the inner surface of the bottom wall 112 of the casing 102 toward the open portion 108 side of the casing 102, and its distal end 109 is detachable from the engine body 11. Connected to As in the example shown in FIG. 2, the mounting cylinder 14 is fixed in advance to the engine body 11, and is formed at the distal end portion 109 of the central cylindrical portion 103 on the male screw formed on the mounting cylinder 14. Therefore, the oil filter 101 is attached to the engine main body 11 by screwing the screw, and the operator rotates the casing 102 by holding the casing 102 with fingers or engaging an appropriate tool with the casing 102. By doing so, the oil filter 101 can be attached and detached.

  The casing 102 is attached to the engine body 11 in such a manner that the open part 108 is closed by the attachment surface 11 a of the engine body 11, and an O-ring 116 fitted into the end part 115 on the open part 108 side is attached to the engine body 11. Sealing is performed in pressure contact with the mounting surface.

  Similar to the example shown in FIG. 3, the filter element 5 is externally fitted to the central cylindrical portion 103 from the distal end portion 109 of the central cylindrical portion 103 and is detachable from the distal end portion 109 of the central cylindrical portion 103. The retaining member 13 to be engaged is fixed to the central cylindrical portion 103. In particular, here, the retaining member 13 is a nut that is screwed into a male screw formed at the distal end portion 109 of the central cylindrical portion 103. In addition, the thing of the structure which latches the filter element 5 by elastically engaging the center cylindrical part 103 like a retaining ring etc. can also be used for the retaining member.

  As a result, the filter element 5 is integrally held in the casing 102 via the central cylindrical portion 103, so that the attachment / removal work with respect to the engine body 11 is facilitated. In addition, the filter element 5 can be removed from the central tubular portion 103 simply by removing the retaining member 13 from the central tubular portion 103, and the filter element 5 can be easily replaced.

  As shown in FIG. 11, the central cylindrical portion 103 is formed separately from the casing 102 in advance, and a connecting cylindrical portion 117 that connects the central cylindrical portion 103 to the bottom wall 112 of the casing 102 includes a casing. 102 is formed separately from 102 and fixed to the bottom wall 112 of the casing 102, and the central cylindrical portion 103 is fitted to the connecting cylindrical portion 117 at the base end portion 118 on the bottom wall 112 side of the casing 102. Then, it is fixed to the bottom wall 112 of the casing 102 via the connecting cylindrical portion 117. In particular, here, since it is formed in the connecting cylindrical portion 117, it is fixed by screwing a male screw formed in the proximal end portion 118 of the central cylindrical portion 103 into the screw.

  Here, the base end portion 118 of the central cylindrical portion 103 is configured to be fitted into the connecting cylindrical portion 117, but conversely, the base end portion 118 of the central cylindrical portion 103 is connected to the inside of the base end portion 118. A configuration in which the cylindrical portion 117 is inserted is also possible. In this case, a screw is formed in the connecting cylindrical portion 117, and a female screw is formed in the proximal end portion 118 of the central cylindrical portion 103.

  The central cylindrical portion 103 is provided with a stopper 120 that abuts the end surface 117 a of the connecting cylindrical portion 117 and restricts the base end portion 118 of the central cylindrical portion 103 from excessively entering the connecting cylindrical portion 117. It is provided in the shape. With this stopper 120, the central cylindrical portion 103 is fixed at an axial position where the end surface 117b on the bottom wall 112 side of the connecting cylindrical portion 117 and the end surface 103a on the proximal end portion 118 side of the central cylindrical portion 103 are substantially aligned. (See FIG. 10).

  As a result, it is possible to prevent damage to the connecting cylindrical portion 117 due to excessive tightening torque and to increase the support rigidity of the connecting cylindrical portion 117 that supports the central cylindrical portion 103. Further, the proximal end portion 118 of the central tubular portion 103 is prevented from projecting from the end surface 117b of the connecting tubular portion 117, and the oil flow in the primary passage 124 of the bypass passage 121 described later is obstructed. You can avoid that.

  Note that an adhesive (for example, an epoxy-based adhesive) is applied to the contact surface between the base end portion 118 of the central cylindrical portion 103 and the connecting cylindrical portion 117 so that the base end portion 118 of the central cylindrical portion 103 and the connecting cylinder are connected. The shape portion 117 is preferably fixed by adhesion in addition to screwing. As a result, it is possible to reliably prevent loosening of the center tubular portion 103, the connecting tubular portion 117, and the tightening torque.

  As described above, since the central cylindrical portion 103 and the casing 102 are separately formed in advance and assembled together, the manufacture becomes easy. Further, since the connecting cylindrical portion 117 for fixing the central cylindrical portion 103 to the casing 102 is a separate member from the casing 102, the manufacturing becomes easier. And since the base end part 118 of the center cylindrical part 103 is fitted and fixed to the connection cylindrical part 117, the center cylindrical part 103 can be fixed to the casing 102 with high support rigidity.

  As shown in FIG. 10, a flange 119 extending outward in the radial direction is formed on the bottom wall 112 side of the casing 102 in the connecting cylindrical portion 117, and the filter element 5 is connected to the flange of the connecting cylindrical portion 117. It is fixed to the central cylindrical portion 103 in a state of being sandwiched between 119 and the retaining member 13.

  As a result, the filter element 5 can be reliably fixed to the central cylindrical portion 103, and a large load does not have to be applied to the bottom wall 112 of the casing 102 for fixing the filter element 5. In addition, the filter element 5 is in close contact with the flange 119 of the connecting cylindrical portion 117 on one end side, and the filter element 5 is in close contact with the retaining member 13 on the other end side. The secondary side 104b can be reliably partitioned.

  The bottom wall 112 and the peripheral wall 113 of the casing 102 are preliminarily formed separately by pressing a steel plate, and the outer peripheral portion of the bottom wall 112 and the end of the peripheral wall 113 are joined and integrated by double winding. Yes. The peripheral wall 113 has a barrel shape in which the central portion in the axial direction is enlarged, and is a tool engaging portion having a polygonal cross section (see FIG. 15).

  In the bottom wall 112, an annular step 132 having an L-shaped cross section is provided inside the tightening coupling portion 131. The annular step 132 makes it easier for the bottom wall 112 of the casing 102 to be elastically deformed when the oil filter 101 is attached to the engine body 11, so that the internal sealing performance of the oil filter 101 can be further improved. .

  The oil filter 101 also has a relief valve 22 that opens and closes a bypass passage 121 that communicates the primary side 104a and the secondary side 104b of the element storage chamber 104. The relief valve 22 has a central cylindrical portion. 103 is accommodated in a valve accommodating chamber 123 defined on the bottom wall 112 side of the casing 102 from the oil recovery path 106.

  Thereby, it is possible to prevent the filter element 5 from being damaged due to an excessive pressure difference between the primary side 104a and the secondary side 104b of the element storage chamber 104 due to clogging of the filter element 5 or the like. In addition, since the relief valve 22 is accommodated inside the central cylindrical portion 103, the relief valve 22 does not interfere with the attachment / detachment of the filter element 5, so that the attachment / detachment of the filter element 5 is facilitated.

  The bypass passage 121 includes a primary passage 124 provided on the bottom wall 112 side of the casing 102 so as to guide oil on the primary side 104 a of the element storage chamber 104 to the valve storage chamber 123, and the valve storage chamber 123 and the element storage. An unfiltered oil circulation hole 125 formed in the peripheral wall of the central cylindrical portion 103 in a manner that communicates with the secondary side 104b of the chamber 104, and the relief valve 22 extends in the valve housing chamber 123 in the axial direction. A valve body 26 is provided so as to advance and retreat to open and close the circulation hole 125 for unfiltered oil, and a spring 27 that biases the valve body 26 toward the fully closed position.

  Thereby, since the surrounding wall of the center cylindrical part 103 can be shared by the housing of the relief valve 22, it can achieve size reduction and reduce the manufacturing cost.

  One end of the spring 27 abuts on the back surface of the valve body 26, and the other end abuts on a spring pin 128 arranged in the diameter direction on the central tubular portion 103, so that the valve body 26 is in contact with the bottom wall 112 of the casing 102. Energize in the direction close to. An oil introduction chamber 130 is provided on the bottom wall 112 side of the valve housing chamber 123. The oil introduction chamber 130 is formed to have a smaller diameter than the valve body 26, and a step between the oil introduction chamber 130 and the valve housing chamber 123. The valve body 26 is regulated by the portion 129 and is held in a fully closed position where the unfiltered oil circulation hole 125 is closed.

  As shown in FIG. 15, the spring pin 128 is attached at an angular position that is substantially the same axial position as the filtered oil circulation hole 107 and shifted in the circumferential direction with respect to the filtered oil circulation hole 107. It is press-fitted into a mounting hole 139 formed in the peripheral wall of the central cylindrical portion 103 and fixed. As shown in FIG. 11, before assembling the central cylindrical portion 103 and the casing 102, the valve body 26 and the spring 27 are inserted from the opening on the distal end portion 109 side of the central cylindrical portion 103, and then the spring pin 128. Is attached to the central cylindrical portion 103, so that the relief valve 22 is assembled to the central cylindrical portion 3.

  As shown in FIG. 10, the pressure on the primary side 104 a of the element housing chamber 104 acts on the front surface of the valve body 26 via the primary side passage 124, and the oil recovery path is formed on the back surface of the valve body 26. The pressure on the secondary side 104b of the element storage chamber 104 is applied by communicating the valve storage chamber 106 with the valve storage chamber 123.

  For this reason, the pressure difference between the primary side 104a and the secondary side 104b of the element accommodating chamber 104 becomes excessive due to clogging of the filter element 5 and the pressure on the primary side 104a acting on the front surface of the valve body 26 When the pressure on the secondary side 104b acting on the back surface of the body 26 is greater than the pressure applied by the spring 27, the valve body 26 is retracted to open the unfiltered oil circulation hole 125 as shown in FIG. The oil on the primary side 104a of the element storage chamber 104 is opened and passes through the primary side passage 124, the oil introduction chamber 130, the valve storage chamber 123, and the unfiltered oil circulation hole 125, and the secondary side of the element storage chamber 104. After flowing into 104 b, it flows into the oil recovery passage 106 through the filtered oil circulation hole 107 and is recovered from the front end 109 side of the central cylindrical portion 103.

  As shown in FIG. 13A, a recess 133 is formed in the radial direction on the inner surface side of the bottom wall 112 of the casing 102. In particular, here, a plurality (six in this case) of the recesses 133 are provided radially from the center of the bottom wall 112 of the casing 102. On the other hand, as described above, the flange 119 extending outward in the radial direction is formed on the bottom wall 112 side of the connecting cylindrical portion 117, and the flange 119 of the connecting cylindrical portion 117 is a recess in the bottom wall 112. The connecting cylindrical portion 117 is fixed to the bottom wall 112 of the casing 102 by being joined to the convex portion 134 provided between the two sides 133.

  Further, as shown in FIG. 13B, an open portion 135a on the outer peripheral side of the empty chamber 135 defined between the concave portion 133 of the bottom wall 112 and the flange 119 of the connecting cylindrical portion 117 is provided in the element accommodating chamber 104. The primary side passage 124 is formed by communicating with the primary side 104a of the first central portion 104a and communicating with the oil introduction chamber 130 inside the central cylindrical portion 103 of the central side opening portion 135b (see FIG. 10).

  The concave portion 133 and the convex portion 134 in the bottom wall 112 are formed on the inner peripheral side of the annular step portion 132, the top surface 134 a of the convex portion 134 is formed lower than the side surface 132 a of the annular step portion 132, and the top surface of the convex portion 34. A step 138 is formed between 134 a and the side surface 132 a of the annular step portion 132. In the assembled state, the flange 119 of the connecting tubular portion 117 enters the inside of the annular step portion 132, and the annular step portion 132 becomes the flange 119. It becomes a form surrounding the outer peripheral side.

  An inner peripheral surface 132b of the annular stepped portion 132 is formed to have a larger diameter than the flange 119 of the connecting cylindrical portion 117, and a portion of the concave portion 133 is covered by the flange 119, and the remaining portion is opened. 135 a is defined so as to open between the outer peripheral surface of the flange 119 and the inner peripheral surface 132 b of the annular step portion 132.

  The convex part 134 is formed in a mode extending radially inward from the inner peripheral surface 132 b of the annular step part 132, and circulates in the concave part 133 on the inner end side of the convex part 134, that is, the center part of the bottom wall 112. A collecting chamber 137 in which oil collects is formed. The collective chamber 137 communicates with the oil introduction chamber 130 inside the central cylindrical portion 103 (see FIG. 10).

  Therefore, the oil on the primary side 104a of the element storage chamber 104 flows into the recess 133 from the outer opening portion 135a, and the diameter of the empty chamber 135 between the recess 133 and the end surface 117b of the connecting cylindrical portion 117 is reduced. After flowing inward in the direction, it flows into the collecting chamber 137 from the central open portion 135b, and then reaches the valve accommodating chamber 123 through the oil introduction chamber 130 inside the central cylindrical portion 103 (see FIG. 12). .

  The top surface 134a of the convex portion 134 of the bottom wall 112 is formed flat, and the end surface 117b on the flange 119 side of the connecting tubular portion 117 joined thereto is also formed flat. The top surface 134a of this convex part 134 and the end surface 117b of the connection cylindrical part 117 are welded by spot welding at the position shown by x in FIG. A projection (not shown) for spot welding is formed on the end surface 117b of the connecting cylindrical portion 117.

  Thereby, the primary side passage 124 can be provided by performing a process of providing unevenness only on the bottom wall 112 side of the casing 102, the end surface 117 b of the connecting cylindrical portion 117 is flat, and the connecting cylindrical portion 117 is specially provided. Therefore, the dimensions of the connecting cylindrical portion 117, particularly the thickness of the flange 119 joined to the bottom wall 112, can be reduced.

  Further, since the connecting cylindrical portion 117 and the bottom wall 112 of the casing 102 can be brought into contact with each other with a large area by the flange 119 of the connecting cylindrical portion 117, the connecting cylindrical portion 117 can be joined to the bottom wall of the casing 102. It is possible to increase the support rigidity of the connecting tubular portion 117 that supports the central tubular portion 103 by being firmly fixed to 112.

  Other configurations, for example, configurations related to the filter element 5 and the element case 44 are the same as those in the first embodiment, and the same reference numerals are given and detailed descriptions thereof are omitted.

  In the oil filter 101 configured as described above, all the components except the O-ring 116 can be made of metal. For example, the bottom wall 112 and the peripheral wall 113 of the casing 102, the connecting cylindrical portion 117, the element case 44, and the valve body 26 of the relief valve 22 can be manufactured by pressing a steel plate, and the central cylindrical portion 103 is made of carbon. It can be manufactured by cutting steel (for example, S45C), and the filter element 5 can be manufactured with a stainless steel mesh. This facilitates reuse and contributes to environmental protection. Further, the filter sheet material constituting the filter element 5 can be made of paper, but if a stainless steel mesh is used, it can be used again by washing and does not need to be replaced with a new one.

  In the above example, as shown in FIG. 14, in the bottom wall 112 of the casing 102, the corners on the outer peripheral side of the concave portion 133 are curved in an arc shape so as to be easily pressed, and the inside of the convex portion 134 is The end on the circumferential side is curved in an arc shape so that it forms a petal shape as a whole as viewed from the open portion 108 side of the casing 102, but the recess 133 allows the outer periphery side and the center portion to communicate with each other. However, it is not limited to such a shape. For example, you may make it form a recessed part and a convex part in a linear external shape.

1 · 101 Oil filter 2 · 102 Casing 3 · 103 Center tubular portion 4 · 104 Element storage chamber 4a · 104a Primary side 4b · 104b Secondary side 5 Filter element 6 · 106 Oil recovery path 7 · 107 Filtered Oil circulation holes 8 and 108 Opening portion 9 and 109 Tip portion 11 Engine body 12 and 112 Bottom wall 13 Retaining member 14 Mounting cylinder 15 and 115 End portion 17 Convex portion 18 Base end portion 19 Flange 21 and 121 Bypass passage 22 Relief valve 23/123 Valve housing chamber 24/124 Primary side passage 25/125 Flow hole 26 for unfiltered oil Valve body 27 Spring 29 Top surface 31 Radial groove 32 Circumferential groove 33 Axial groove 35 Projection 41 Crest 43 Holder 44 Element case 46 Peripheral wall 47 Bottom wall 48 Center hole 51 Recess 113 Peripheral wall 117 Connecting cylindrical part, 117a, 117b End face 118 Base end part 119 Flange 133 Concave part 134 Protruding part 135 Empty room, 135a Opening part on the outer peripheral side, 135b Opening part on the central side

Claims (13)

A casing having a bottomed cylindrical shape, a central cylindrical portion provided in an axially extending manner at the central portion of the casing, and an element housing defined between the central cylindrical portion and the casing A cylindrical filter element housed in the chamber, and in a mode of communicating with the peripheral wall of the central tubular portion the oil recovery path defined therein and the secondary side of the element housing chamber An oil filter with a circulation hole for filtered oil,
The central cylindrical portion is provided in a form protruding from the inner surface of the bottom wall of the casing toward the open portion side of the casing, and a tip portion of the central cylindrical portion is detachably connected to the engine body, and the filter element Is attached to the central cylindrical portion from the distal end portion of the central cylindrical portion, and is a retaining member that is detachably engaged with the distal end portion of the central cylindrical portion with respect to the central cylindrical portion. An oil filter characterized by being fixed.   The relief valve further includes a relief valve that opens and closes a bypass passage that communicates the primary side and the secondary side of the element storage chamber, and the relief valve is located at the bottom of the casing from the oil recovery path inside the central cylindrical portion. The oil filter according to claim 1, wherein the oil filter is accommodated in a valve accommodating chamber defined on a wall side.   The bypass passage includes a primary passage provided on a bottom wall side of the casing so as to guide oil on a primary side of the element storage chamber to the valve storage chamber, and the valve storage chamber and the element storage chamber. And an unfiltered oil circulation hole formed in the peripheral wall of the central cylindrical portion in a mode of communicating with the secondary side, and the relief valve moves forward and backward in the valve housing chamber in the axial direction. The oil filter according to claim 2, further comprising: a valve body provided to open and close the oil circulation hole; and a spring that biases the valve body toward a fully closed position.   The casing includes a connecting convex portion that protrudes in an axial direction from an inner surface of the bottom wall, and the central cylindrical portion is formed separately from the casing in advance, and is formed at a base end portion on the bottom wall side of the casing. The oil filter according to any one of claims 1 to 3, wherein the oil filter is fixed to the bottom wall of the casing in a manner in which the connecting convex portion is fitted.   The primary side passage is formed in a radial direction on the end surface of the central cylindrical portion in contact with the bottom wall of the casing in the radial direction and on the inner peripheral side of the end surface of the central cylindrical portion in the circumferential direction. The circumferential groove is formed on the outer circumferential surface of the connecting projection, and the radial groove and the axial groove are communicated with each other through the circumferential groove. The oil filter according to claim 4.   A projection that restricts the valve body is formed on the top surface of the connection convex portion so as to protrude in the axial direction, and the top surface of the connection convex portion and the front surface of the valve body are always kept apart. The oil filter according to claim 4 or 5, wherein the oil filter is configured as described above.   6. The oil filter according to claim 4, wherein a concave portion is formed on a top surface of the connecting convex portion in a form communicating with the primary side passage.   A flange extending outward in the radial direction is formed at a base end portion on the bottom wall side of the casing in the central cylindrical portion, and the filter element is sandwiched between the flange and the retaining member. The oil filter according to any one of claims 1 to 7, wherein the oil filter is fixed to the central cylindrical portion in an aspect.   The central cylindrical part is molded separately from the casing in advance, and a connecting cylindrical part that connects the central cylindrical part to the bottom wall of the casing is molded in advance separately from the casing. The casing is fixed to the bottom wall of the casing, and the central cylindrical portion is fitted to the connecting cylindrical portion at the bottom end of the casing on the bottom wall side through the connecting cylindrical portion. The oil filter according to any one of claims 1 to 3, wherein the oil filter is fixed to a wall.   A concave portion is formed in the radial direction on the inner surface side of the bottom wall of the casing, and a flange extending radially outward is formed on the bottom wall side of the casing in the connecting cylindrical portion, and the flange in the bottom wall is formed. The flange is joined to a convex portion provided between the concave portions, the connecting cylindrical portion is fixed to the bottom wall of the casing, and is defined between the concave portion of the bottom wall and the flange of the connecting cylindrical portion. The open portion on the outer peripheral side of the empty chamber communicates with the primary side of the element storage chamber, and the open passage on the center side communicates with the inside of the central cylindrical portion to form the primary passage. The oil filter according to claim 9, wherein the oil filter is characterized in that:   A flange extending radially outward is formed on the bottom wall side of the casing in the connecting cylindrical portion, and the filter element is sandwiched between the flange of the connecting cylindrical portion and the retaining member. The oil filter according to claim 9 or 10, wherein the oil filter is fixed to the central cylindrical portion in an aspect.   The filter element has a thick cylindrical shape with a large number of folds formed by folding the filtration sheet material in the circumferential direction, and is held by a cylindrical holder fitted in the center thereof. The oil filter according to any one of claims 1 to 11, wherein the oil filter is housed in the element case in a state where the portion is inclined with respect to the radial direction.   The element case has a bottomed cylindrical shape including a peripheral wall partially covering the outer peripheral side of the filter element, and a bottom wall having a central hole into which the central cylindrical portion is inserted. The oil filter according to claim 12, wherein a portion of the filter element that is not covered is provided so as to be positioned on a bottom wall side of the casing.

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