Fluid filter

Abstract

To provide a fluid filter where a filter element can be easily adjusted to a specified position in a filter case.SOLUTION: A fluid filter comprises: an engagement protrusion part 211 by which the rotation of a filter element to a filter case is regulated in a state of accommodating the filter element in the internal space of the filter case; an engagement groove part 344; and a guide part 345. An engagement protrusion part 211 is guided by the guide part 345 and introduced to the engagement groove part 344 when the filter element is inserted into the internal space of the filter case. The engagement protrusion part 211 is engaged with the engagement groove part 344 when the insertion of the filter element is completed and the rotation of the filter element in the filter case is regulated.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a fluid filter for filtering fluids such as oil.

Background Art

[0002] Conventionally, fluid filters for filtering fluids such as water, fuel, oil, air, etc. have been used in a wide range of industrial fields. In this type of fluid filter, a filter case that houses a cylindrical filter element inside is attached to the opening of the filter head, and the fuel flowing in from the inflow path of the filter head is filtered by passing it from the outside to the inside of the filter element, and the filtered fuel is made to flow out from the inside of the filter element to the outflow path of the filter head (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described fluid filter, to replace the filter element, first, the filter case and the filter element are removed from the filter head, then the old filter element inside the filter case is taken out, and after setting a new filter element inside the filter case (or after attaching a new filter element to the outflow path of the filter head), the filter case is attached to the filter head.

[0005] For example, if a specific position is designated within the filter case, and when setting a new filter element within the filter case, it is necessary to align the circumferential position of the filter element with the aforementioned specific position, then the filter element must be set after knowing the specific position within the filter case, which may make the filter element replacement process complicated.

[0006] This invention has been made in view of these problems, and aims to provide a fluid filter that allows the filter element to be easily aligned to a specific position within the filter case. [Means for solving the problem]

[0007] To solve the aforementioned problems, the fluid filter according to the present invention comprises a filter head having a fluid inlet and outlet, a bottomed cylindrical filter case formed with an open upper end and an internal space, the upper end of which is detachably attached to the filter head, a hollow cylindrical filter element detachably housed in the internal space of the filter case and filtering fluid by passing it through, and a rotation restricting means for restricting the rotation of the filter element relative to the filter case while the filter element is housed in the internal space. The filter element comprises a filter medium and a lower plate provided at the lower end of the filter medium. The rotation restricting means is located at the bottom of the filter case. side inner circumference surface Provided along , protruding radially inward from the inner circumferential surface side Engaging protrusion and, Multiple in the circumferential direction on the outer surface of the lower plate It is configured to include an engagement recess provided, The engagement recess has an engagement groove that engages with the engagement projection in the vertical direction, and a guide portion having an inclined surface that guides the engagement projection to the engagement groove, and the engagement groove is The aforementioned The guide portion is recessed radially inward from the outer circumferential surface of the lower plate and extends downward from the upper end of the lower plate, forming between a pair of vertical surfaces that are spaced apart from each other in the circumferential direction, the pair of vertical surfaces consisting of a long vertical surface and a short vertical surface that extends shorter downward than the long vertical surface, the inclined surface of the guide portion connects the lower end of the long vertical surface in one of the two circumferentially adjacent engagement recesses on the lower end of the lower plate and the lower end of the short vertical surface in the other engagement recess, and is inclined upward from the lower end of the long vertical surface in one engagement recess to the lower end of the short vertical surface in the other engagement recess. When inserting the filter element into the internal space of the filter case, the engaging projection It comes into contact with the inclined surface and is guided by the inclined surface to the engagement groove of the other engagement recess, and the other engagement recess Engagement groove By contacting the aforementioned perpendicular surface of the long side The filter element within the filter case To the circumferential direction rotate but Regulations The engaging projection and the other engaging recess engage. Configured in this way did .

[0010] Furthermore, in the fluid filter having the above configuration, a retainer is provided at the bottom of the filter case to receive and hold the lower part of the filter element, and the inner circumference of the retainer surface It is preferable that the engaging projection is formed thereon. [Effects of the Invention]

[0011] According to the fluid filter of the present invention, a rotation restricting means for restricting the rotation of the filter element relative to the filter case is located on the bottom surface of the filter case. side inner circumference surface An engaging projection provided along and a filter element Multiple in the circumferential direction of the outer surface of the lower plate that it possesses It is configured to include an engagement recess provided The engaging recess has an engaging groove that engages with the engaging projection in the vertical direction, and a guide portion having an inclined surface that guides the engaging projection into the engaging groove. The engaging groove is recessed radially inward from the outer circumferential surface of the lower plate and is formed between the opposing long-side vertical surface and short-side vertical surface of the lower plate in the circumferential direction. The inclined surface of the guide portion connects the lower end of the long-side vertical surface of one of the two circumferentially adjacent engaging recesses on the lower end side of the lower plate to the lower end of the short-side vertical surface of the other engaging recess, and is inclined upward from the lower end of the long-side vertical surface of one engaging recess to the lower end of the short-side vertical surface of the other engaging recess. When inserting the filter element into the internal space of the filter case, the engaging projection acts as a guide. It comes into contact with the inclined surface and is guided by the inclined surface to the engagement groove of the engagement recess, Engagement groove By contacting the surface perpendicular to the long side Filter element within filter case In the circumferential direction rotate but Regulations The engaging protrusion and the engaging recess engage as a result. The position of the engagement groove in the filter element can be easily aligned with the position of the engagement projection provided along the inner circumference of the bottom surface of the filter case. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view showing the appearance of the fluid filter according to the present invention. [Figure 2] This is a cross-sectional view showing the vertical cross-section of the fluid filter described above. [Figure 3] This is an exploded perspective view showing the main components of the fluid filter described above. [Figure 4] Figure 4(a) is a perspective view showing the appearance of the components constituting the filter element of the fluid filter described above, with Figure 4(b) being a perspective view showing the appearance of the upper plate and Figure 4(b) being a perspective view showing the appearance of the lower plate. [Figure 5] Figure 5(a) is a perspective view showing the configuration of the support members of the fluid filter described above, with Figure 5(b) being a perspective view showing the external appearance of the outer support member and Figure 5(b) being a perspective view showing the external appearance of the inner support member. [Figure 6]It is a cross-sectional view showing the state of each part when the support member of the fluid filter is attached inside the filter case. [Figure 7] It is a perspective view showing the state when looking down from above the opening of the filter case removed from the filter head of the fluid filter. [Figure 8] It is a cross-sectional view showing the movement of each part when the filter element is attached inside the filter case. [Figure 9] It is a perspective view showing the movement of the lower plate of the filter element with respect to the retainer inside the filter case when the filter element is attached inside the filter case. [Figure 10] It is a cross-sectional view showing the movement of each part when the filter case containing the filter element is attached to the filter head.

Mode for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the appearance of the fluid filter 1 of the present embodiment. FIG. 2 is a longitudinal sectional view at the position of the A-A' line shown in FIG. 1. FIG. 3 is an exploded perspective view showing the main configuration of the fluid filter 1. When referring to the vertical direction of the fluid filter 1 of the present embodiment, it follows the direction of the arrow shown in FIG. 1.

[0015] The fluid filter 1 shown in FIG. 1 filters the hydraulic oil flowing in from the inlet 101 formed in the filter head 10 by the filter element 30 (see FIGS. 2 and 3) housed in the filter case 20, and discharges it from the outlet 102 formed in the filter head 10. As shown in FIG. 2, a relief valve 11 is provided inside the inlet 101 of the filter head 10. When the pressure of the hydraulic oil flowing in from the inlet 101 becomes larger than a predetermined value with respect to the pressure of the hydraulic oil flowing out from the outlet 102, the relief valve 11 opens and allows the hydraulic oil flowing in from the inlet 101 to flow directly out to the outlet 102.

[0016] As shown in Figure 2, an opening is formed below the filter head 10 to which the upper end of the filter case 20 is attached. On the inner circumferential surface of this opening, a head-side female thread 103 (see Figure 10(a) in more detail) is formed, which engages with a male thread 201 (see also Figure 3) formed on the upper outer circumference of the filter case 20. In addition, a fitting port 104 is provided at the center of the opening in the filter head 10, into which a fluid communication port 337 (see also Figure 3) formed in the center of the upper plate 33 of the filter element 30 is fitted. This fitting port 104 communicates with the outlet 102 of the filter head 10.

[0017] The filter case 20 has a bottomed cylindrical shape with an open upper end and an internal space (see Figure 3). A mounting hole 203 is formed in the center of the inner bottom of the filter case 20, to which the tip of the inner support member 42 is attached. A case-side female thread 204 is formed on the inner circumferential surface of this mounting hole 203 (see Figure 7(a) for more details), and the case-side female thread 204 is screwed into a support member-side male thread 421 (see Figure 3) formed on the tip of the inner support member 42. Furthermore, the retainer 21 and compression coil spring 22 are fixed between the inner support member 42 and the inner bottom of the filter case 20 by screwing the support member-side male thread 421 and the case-side female thread 204 together. As shown in Figure 3, each of the inner circumferential surfaces of the retainer 21 is a filter Two engaging protrusions 211, each having a linear convex shape extending in the axial direction, are formed at opposing positions on the case 20. These engaging protrusions 211 engage with engaging grooves 344 formed on the lower plate 34, which will be described later (details will be described later).

[0018] As shown in Figure 2, the filter element 30 consists of a filter medium 31, a protector 32 that houses the filter medium 31, an upper plate 33 fixed to the upper ends of the filter medium 31 and the protector 32, and a lower plate 34 fixed to the lower ends of the filter medium 31 and the protector 32. The filter medium 31 is formed into a roughly hollow cylindrical shape with a chrysanthemum-shaped cross-section by joining the ends of a filter medium folded in a bellows-like manner. The protector 32 has a cylindrical shape and houses the filter medium 31 inside. In addition, as shown in Figure 3, the surface of the protector 32 is provided with numerous small holes 321, and the hydraulic fluid that passes through these small holes 321 is filtered by the filter medium 31. The upper end surfaces of the filter medium 31 and the protector 32 are fixed to the upper plate 33, and the lower end surfaces of the filter medium 31 and the protector 32 are fixed to the lower plate 34. The filter media 31 and protector 32 can be fixed to the upper plate 33 and lower plate 34 by bonding with adhesive, or by conventional methods.

[0019] Figure 4 shows the external shapes of the upper plate 33 and the lower plate 34. In Figure 4, (a) is a perspective view showing the external shape of the upper plate 33 when viewed from diagonally below (in other words, a perspective view of the back side of the upper plate 33), and (b) is a perspective view showing the external shape of the lower plate 34 when viewed from diagonally below. As shown in Figure 4(a), the back side of the upper plate 33 has a peripheral edge portion 331 that extends downward along its outer edge. Flexible fixing members 332 extend diagonally upward from two opposing locations on this peripheral edge portion 331, and engaging projections 333 are formed at their tips. These engaging projections 333 engage with engaging recesses 202 (see Figure 3) formed on the upper inner side of the filter case 20. Furthermore, a lever member 334 is formed on the engaging projection 333 to bend the fixing member 332. As shown in Figure 2, when the engaging projection 333 is engaged with the engaging recess 202, for example, as indicated by the arrow in Figure 8(c), the tip of the lever member 334 can be bent inward, causing the fixing member 332 to bend and releasing the engagement between the engaging projection 333 and the engaging recess 202.

[0020] Returning to Figure 4(a), an inner cylinder portion 335 is formed to protrude downward from the center of the back surface of the upper plate 33. Two engagement grooves 336 are formed on the inner circumferential surface of this inner cylinder portion 335 at opposing positions, which engage with the engagement projection 412 formed on the upper end of the outer support member 41, which will be described later. Also, as shown in Figures 2, 3 and 6, a fluid communication port 337 is formed to protrude upward from the center of the upper surface of the upper plate 33, for allowing the hydraulic oil filtered by the filter material 31 to flow to the filter head 10. Furthermore, as shown in Figure 4(a), on the back side of the upper plate 33, the plane from the outside of the inner cylinder portion 335 to the inside of the aforementioned peripheral edge portion 331 becomes a fixing surface 338 to which the filter material 31 and protector 32 are fixed.

[0021] As shown in Figure 4(b), a support member insertion opening 341 is provided in the center of the lower plate 34 through which the outer support member 41 is inserted. A flange contact surface 342 is formed on the lower peripheral edge of this support member insertion opening 341, which contacts the upper surface of the flange portion 411 (see Figure 5(b)) formed on the lower part of the outer support member 41. Six engagement recesses 343, each consisting of an engagement groove 344 and a guide portion 345, are provided on the lower outer peripheral surface of the lower plate 34 at equal intervals in the circumferential direction of the lower plate 34. The engagement groove 344 is formed sandwiched between a long vertical surface 346 extending downward from the upper surface of the lower plate 34 and a short vertical surface 347 that is shorter than the long vertical surface 346 extending downward from the upper surface of the lower plate 34. Furthermore, the inclined surface extending from the lower end of the long vertical surface 346 to the lower end of the short vertical surface 347, which forms the engagement groove 344 to the right in Figure 4(b), serves as the guide portion 345. Alternatively, the short vertical surface It can also be said that the inclined surface extending from the lower end of 347 to the lower end of the long-side vertical surface 346, which forms the engagement groove 344 to the left in Figure 4(b), is the guide portion 345.

[0022] As shown in Figure 2, the support member 40 is inserted into the hollow portion of the filter material 31 of the filter element 30 described above, and supports the filter material 31 from the inside against the pressure of the hydraulic fluid applied to the outside of the filter material 31. The support member 40 is composed of an outer support member 41 and an inner support member 42, as shown in Figure 5. Figure 5 is a perspective view showing the external shape of the outer support member 41 and the inner support member 42, where (a) is a perspective view of the outer support member 41 and (b) is a perspective view of the inner support member 42.

[0023] As shown in Figure 5(a), the outer support member 41 has a cylindrical shape, and two upward-extending engaging protrusions 412 are formed on its upper end surface at opposing positions. A flange 411 is formed on the lower outer peripheral surface of the outer support member 41, which abuts against the flange contact surface 342 shown in Figure 4(b), and the lower end of the filter element 30 is supported by this flange 411. An inner support member contact surface 413 (shown by hatching in Figure 5(a)) is formed on the lower part of the inner peripheral surface of the outer support member 41. It abuts against the outer support member contact surface 422 of the inner support member 42 (see Figure 5(b)). On this inner support member contact surface 413, upward-extending linear engaging protrusions 414 are formed at opposing positions. In addition, a plurality of oval-shaped outer communication holes 415 extending in the circumferential direction are provided on the surface (hollow cylindrical wall) of the outer support member 41.

[0024] Next, the inner support member 42 has a cylindrical shape as shown in Figure 5(b), and its outer diameter is smaller than the inner diameter of the outer support member 41. This makes it possible to insert the inner support member 42 into the outer support member 41. A male thread 421 is formed on the lower tip of the inner support member 42. The male thread 421 is designed to screw into a female thread 204 (see Figure 6(a)) formed on the inner circumferential surface of a mounting hole 203 provided at the bottom of the filter case 20. An outer support member contact surface 422 is formed on the lower part of the surface (hollow cylindrical wall) of the inner support member 42, which contacts the inner support member contact surface 413 shown in Figure 5(a). This outer support member contact surface 422 is provided with an engaging recess 423 that engages with the engaging projection 414 shown in Figure 5(a). Furthermore, multiple oval-shaped inner communication holes 424 extending in the circumferential direction are provided on the surface of the inner support member 42 at positions corresponding to the outer communication holes 415 shown in Figure 5(a).

[0025] When attaching the outer support member 41 and inner support member 42 described above to the filter case 20, first insert the lower tip of the inner support member 42 through the upper opening of the outer support member 41. Then, align the position of the engaging recess 423 of the inner support member 42 with the position of the engaging projection 414 of the outer support member 41, and bring the outer support member contact surface 422 into contact with the inner support member contact surface 413. As a result, the engaging projection 414 and the engaging recess 423 engage, and while engaged, the outer support member 41 can move downward relative to the inner support member 42, and the inner support member 42 can move upward relative to the outer support member 41, but rotation in the circumferential direction of the outer support member 41 and the inner support member 42 is restricted. Therefore, it is possible to prevent the circumferential positional misalignment of the outer communication hole 415 and the inner communication hole 424.

[0026] When assembling the support member 40 into the filter case 20, with the retainer 21 and compression coil spring 22 placed on the bottom surface of the filter case 20, the support member side male thread 201 formed on the tip of the inner support member 42 is screwed into the case side female thread 204 formed in the mounting hole 203 provided on the bottom of the filter case 20. As this screwing progresses, the compression coil spring 22 is compressed by the flange portion 411 formed on the lower part of the outer support member 42, and the retainer 21 and compression coil spring 22 are fixed to the bottom surface of the filter case 20. At this time, the inner support member contact surface 413 of the outer support member 41 (see Figure 5(a)) and, The inner support member 42 is in contact with the outer support member contact surface 422 (see Figure 5(b)), and in this state, the positions of the outer communication hole 415 and the inner communication hole 424 are completely misaligned. Therefore, the outside of the outer support member 41 and the inside of the inner support member 42 are separated.

[0027] Then, as shown in Figure 6(b), when the male screw 421 on the support member side is fully screwed in, the retainer 21 is fixed to the bottom surface of the filter case 20 by the inner support member 42. At this time, the contact surface 413 of the inner support member and the contact surface 422 of the outer support member are still in contact, so the outside of the outer support member 41 and the inside of the inner support member 42 are separated. Also, since the compression coil spring 22 has room to compress further, the outer support member 41 is in a state where it can move further downward.

[0028] Next, the flow of the hydraulic fluid filtered by the fluid filter 1 with the above-described configuration will be explained with reference to Figures 2 and 7. Here, Figure 7 is a perspective view showing the opening of the filter case 20 viewed from above, with the filter case 20 removed from the filter head 10. As indicated by the arrow in Figure 2, the hydraulic fluid flowing in from the inlet 101 of the filter head 10 reaches the upper surface of the upper plate 33. Here, as shown in Figure 7, a gap G is provided between the opening of the filter case 20 and the upper plate 33, and the hydraulic fluid that reaches the upper surface of the upper plate 33 flows into this gap G. The hydraulic fluid that flows into the gap G passes through the small holes 321 of the protector 32 (see Figure 3), is filtered by the filter material 31 as shown in Figure 2, and then flows into the inside of the inner support member 42 through the outer communication hole 415 of the outer support member 41 and the inner communication hole 424 of the inner support member 42. The hydraulic fluid then flows from the inside of the inner support member 42 through the fluid communication hole 338 of the upper plate 33 into the filter head 10 and out to the outside through the outlet 102.

[0029] Next, with reference to Figures 8 to 10, the movement of each part when replacing the filter element 30 inside the filter case 20 will be explained. Figure 8 is a cross-sectional view showing the process from removing the filter element 30 from the filter case 20 to installing the new filter element 30 into the filter case 20. Figure 9 is a perspective view showing the process from when the filter element 30 is installed in the filter case 20 until the engagement groove 344 of the lower plate 32 engages with the engagement projection 211 of the retainer 21. Figure 10 is a cross-sectional view showing the process from when the filter case 20 with the filter element 30 installed is installed into the filter head 10.

[0030] First, as shown in Figure 8(a), when removing the filter element 30 from the filter case 20, or inserting the filter element 30 into the filter case 20, the inner support member contact surface 413 and the outer support member contact surface 422 are in contact, similar to the state shown in Figure 6(b). As a result, the space between the outside of the outer support member 41 and the inside of the inner support member 42 is blocked. Therefore, even if hydraulic fluid remains in the filter case 20, for example, the hydraulic fluid before filtration and the hydraulic fluid after filtration will not mix. Consequently, there is little risk of reduced-clean hydraulic fluid leaking out of the fluid filter 1 after replacing the filter element 30.

[0031] In this embodiment, as shown in Figure 8(b), when the engaging projection 333 of the upper plate 33 is not engaged with the engaging recess 202 of the filter case 20, the positions of the outer communication hole 415 and the inner communication hole 424 are completely misaligned, and the space between the outside of the outer support member 41 and the inside of the inner support member 42 is blocked. However, when the filter element 30 is removed from the filter case 20, if the positions of the outer communication hole 415 and the inner communication hole 424 are misaligned (the area of ​​the hole communicating from the outside of the outer support member 41 to the inside of the inner support member 42 is reduced), the amount of degraded hydraulic fluid flowing into the inside of the inner support member 42 is reduced. This can be expected.

[0032] Next, the new filter element 30 is inserted into the filter case 20, and the filter element 30 is rotated circumferentially so that the engaging projection 412 formed on the upper end of the outer support member 41 enters the engaging groove 336 of the upper plate 33 shown in Figure 4(a). Once the engaging projection 412 enters the engaging groove 336 and the filter element 30 is further inserted into the filter case 20, the guide portion 345 of the lower plate 34 (see Figure 4(b)) will eventually come into contact with the engaging projection 211 of the retainer 21, as shown in Figure 8(b). If the engaging groove 344 of the lower plate 34 shown in Figure 4(b) does not engage with the engaging projection 211 of the retainer 21, the upper plate 33 shown in Figure 7 is rotated clockwise. Then, the engaging projection 412 of the outer support member 41 comes into contact with the stepped surface st of the engaging groove 336 shown in Figure 4(b), and as a result, the filter material 31, protector 32, and lower plate 34 also rotate as the upper plate 33 rotates.

[0033] As a result, when the upper plate 33 is rotated clockwise, the lower plate 34 also rotates clockwise as shown in Figure 9(a), and the guide portion 345 moves clockwise while contacting the engaging projection 211 of the retainer 21. As a result, as shown in Figure 9(b), the filter element 30 gradually moves downward in accordance with the inclination of the guide portion 345, and the engaging groove portion 344 approaches the engaging projection 211. Finally, as shown in Figure 9(c), the long side vertical surface 346 of the lower plate 34 abuts against the engaging projection 211 of the retainer 21, restricting further rotation of the lower plate 34 and guiding the engaging groove portion 344 to the position of the engaging projection 211. This allows the lower plate 34 (and thus the filter element 30) to move downward along the engaging projection 211.

[0034] In this way, by forming a guide portion 345 at the lower part of the lower plate 34, the engagement groove portion 344 formed at the lower part of the lower plate 34 can be easily engaged with the engagement projection portion 211 of the retainer 21 simply by rotating the filter element 30 clockwise. Furthermore, since the six engagement recesses 343, each composed of an engagement groove portion 344 and a guide portion 345, are provided at equal intervals in the circumferential direction at the lower part of the lower plate 34, the angle by which the filter element 30 must be rotated clockwise before the engagement groove portion 344 of the lower plate 34 engages with the engagement projection portion 211 of the retainer 21 can be reduced.

[0035] Then, when the filter element 30 is lowered further in the state shown in Figure 9(c), the fixing member 332 of the upper plate 33 bends in the direction of the arrow in the figure, as shown in Figure 8(b). Subsequently, as shown in Figure 8(c), when the engaging projection 333 shown in Figure 4(a) enters the engaging recess 202 of the filter case 20, the bending of the fixing member 332 returns to its original position, and the engaging projection 333 and the engaging recess 202 engage, locking the upper plate 33 to the filter case 20. Furthermore, by lowering the filter element 30 further, the flange contact surface 342 of the lower plate 34 (see Figure 4(b)) pushes down the flange portion 411 of the outer support member 41 (see Figure 5(a)). As a result, the inner support member contact surface 413 and the outer support member contact surface 422 are separated, and the outer support member 41 moves downward relative to the inner support member 42, so that a part of the outer communication hole 415 overlaps with the inner communication hole 424, and the outside of the outer support member 41 and the inside of the inner support member 41 are in communication.

[0036] When removing the filter element 30 from the filter case 20 in the state shown in Figure 8(c), bending the lever member 334 of the upper plate 33 inward (bending in the direction of the arrow in Figure 8(c)) causes the fixing member 332 to bend inward into the filter case 20, thereby releasing the engagement of the engaging projection 333 with the engaging recess 202. At this time, the biasing force of the compression coil spring 22 pushes up the outer support member 41, causing the filter element 30 to move upward, and as shown in Figure 8(b), the upper plate 33 is released. The filter element will protrude at a position higher than the opening of the filter case 20. This makes it easier to grasp the filter element 30 and to remove the filter element 30 from the filter case 20.

[0037] Next, referring to Figure 10, the movement of each part when attaching the filter case 20 (see Figure 8(c)) containing the filter element 30 to the filter head 10 will be explained. In Figure 10(b), an enlarged view of the area m1 enclosed by the dashed line is also shown. In Figure 10(c), an enlarged view of the area m2 enclosed by the dashed line is also shown.

[0038] First, as shown in Figure 10(a), the male thread 201 on the case side of the filter case 20, which houses the filter element 30, is screwed into the female thread 103 on the head side of the filter head 10. As this screwing progresses, the filter case 20 gradually moves upward, and eventually the fluid communication port 337 of the upper plate 33 fits into the fitting port 104 of the filter head 10. As the screwing progresses further, as shown in Figure 10(b), the open end face of the fitting port 104 comes into contact with the upper plate 33. In this state, as shown in the enlarged view of region m1, there is still a gap between the case contact surface 105 of the filter head 10 and the open end surface 205 of the filter case 20, and there is room for the engaging projection 333 formed on the upper plate 33 to move downward inside the engaging recess 202 of the filter case 20 (see Figure 8(c)). As the screwing of the filter case 20 progresses, the filter case 20 rises along with the screwing, but the upper plate 33 (and thus the filter element 30) is prevented from rising by the open end surface of the fitting opening 104.

[0039] Therefore, inside the filter case 20, the outer support member 41 remains stationary while only the inner support member 42 rises as the filter case 20 is screwed in, causing the position of the inner communication hole 424 to approach the position of the outer communication hole 415. Then, as shown in Figure 10(c) and the enlarged view of region m2, when the open end face 205 of the filter case 20 contacts the case contact surface 105 of the filter head 10, the upward movement of the filter case 20 due to screwing stops, and at this point the positions of the outer communication hole 415 and the inner communication hole 424 coincide. This completes the attachment of the filter case 20 to the filter head 10. To remove the filter case 20 from the filter head 10, the movements are in the reverse order of those described above.

[0040] Here, when removing the filter case 20 from the filter head 10 (see Figure 10(a)) from the state in which the filter case 20 is attached to the filter head 10 (see Figure 10(c)), the engaging projection 333 of the upper plate 33 engages with the engaging recess 202 of the filter case 20. Therefore, when removing the filter case 20 from the filter head 10, the fluid communication hole 337 of the upper plate 33 is pulled out from the fitting opening 104 of the filter head 10. Consequently, when replacing the filter element 30, the procedure is to replace the filter element 30 housed inside the removed filter case 20 with a new one, and then attach the filter case 20 containing the new filter element 30 to the filter head 10.

[0041] If the engaging projection 333 of the upper plate 33 and the engaging recess 202 of the filter case 20 were not formed, the procedure for replacing the filter element 30 may differ depending on the orientation in which the fluid filter 1 is positioned. For example, suppose the fluid filter 1 is positioned in the opposite orientation to that shown in Figure 10(c), where the filter head 10 is positioned above the filter case 20, where the filter head 10 is positioned below the filter case 20 (in other words, the filter case 20 is positioned above the filter head 10). In this case, when the filter case 20 is removed from the filter head 10, there is a possibility that only the filter case 20 will be removed while the fluid communication hole 337 of the upper plate 33 remains engaged with the fitting opening 104 of the filter head 10.

[0042] In such cases, the procedure for replacing the filter element involves first removing the filter case 20 from the filter head 10, then pulling out the fluid communication hole 337 of the filter element 30 from the fitting port 104 of the filter head 10, fitting the fluid communication hole 337 of the new filter element 30 into the fitting port 104, and finally attaching the filter case 20 to the filter head 10. Therefore, the procedure for replacing the filter element 30 may differ depending on the orientation in which the fluid filter 1 is positioned, which could complicate the replacement process.

[0043] In contrast, in the fluid filter 1 of this embodiment, the engaging projection 333 of the upper plate 33 engages with the engaging recess 202 of the filter case 20. Therefore, regardless of the orientation of the fluid filter 1, the filter case 20 is always removed from the filter head 10 with the filter element 30 housed inside. This has the advantage that the procedure for replacing the filter element 30 is consistent regardless of the orientation in which the fluid filter 1 is positioned.

[0044] Furthermore, the fluid filter according to the present invention can be used, for example, as a return filter to filter the hydraulic fluid that returns from a hydraulic device after it has been supplied from a tank to a hydraulic device by a hydraulic pump, or as a suction filter to filter the hydraulic fluid supplied from the tank to the hydraulic pump. In addition, the filtration target is not limited to hydraulic fluid; similar effects can be obtained by applying it to filters of other fluids such as fuel. [Explanation of Symbols]

[0045] 1. Fluid filter 10 filter heads 20 filter cases 30 filter elements 31 Filter media 32 Protector 33 Upper Plate 24 Lower Plate 40 Support member 41 Outer support member 42 Inner support member

Claims

1. A filter head having a fluid inlet and outlet, A filter case formed in the shape of a bottomed cylinder with an open upper end and an internal space, the upper end of which is connected to the filter head and detachably attached, A hollow cylindrical filter element is detachably housed within the internal space of the filter case and performs filtration by allowing fluid to pass through it. With the filter element housed within the internal space, the system includes rotation restricting means for restricting the rotation of the filter element relative to the filter case, The filter element comprises a filter medium and a lower plate provided at the lower end of the filter medium. The rotation restricting means is An engaging projection is provided along the inner circumferential surface on the bottom side of the filter case, and protrudes radially inward from the inner circumferential surface side, The lower plate is configured to include a plurality of engagement recesses provided in the circumferential direction on the outer surface of the lower plate, The engagement recess has an engagement groove that engages with the engagement projection in the vertical direction, and a guide portion having an inclined surface that guides the engagement projection to the engagement groove. The engagement groove is recessed radially inward from the outer circumferential surface of the lower plate and extends downward from the upper end of the lower plate, forming between a pair of vertical surfaces that are spaced apart from each other in the circumferential direction. The pair of vertical surfaces consist of a long-side vertical surface and a short-side vertical surface that extends less downward than the long-side vertical surface. The inclined surface of the guide portion connects the lower end of the long side vertical surface of one of the two circumferentially adjacent engagement recesses on the lower end side of the lower plate, and is inclined upward from the lower end of the long side vertical surface of one of the engagement recesses to the lower end of the short side vertical surface of the other engagement recess. A fluid filter characterized in that, when the filter element is inserted into the internal space of the filter case, the engaging projection contacts the inclined surface and is guided by the inclined surface to the engaging groove of the other engaging recess, and the rotation of the filter element in the circumferential direction within the filter case is restricted by contact with the surface perpendicular to the long side of the engaging groove in the other engaging recess, thereby engaging the engaging projection with the other engaging recess.

2. The fluid filter according to claim 1, characterized in that a retainer for receiving and holding the lower part of the filter element is provided at the bottom of the filter case, and the engaging projection is formed on the inner circumferential surface of the retainer.

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