Patent Description:
<CIT> discloses a filter structure in which lid-side protruding portions protruding toward an end surface of a filter element are formed on a lower surface of a lid member, and a filter-side recessed portion having a shape fitting to the lid-side protruding portions is formed in the filter element.

In the invention described in <CIT>, by cutting the lid-side protruding portions and the filter-side recessed portion of a component in which the lid-side protruding portions and the filter-side recessed portion are formed (a so-called genuine product), a component in which the lid-side protruding portions or the filter-side recessed portion are not formed (so-called a non-genuine product) becomes usable. Use of the non-genuine product possibly results in deterioration of filtration performance and a leakage of liquid.

<CIT> and <CIT>each disclose a filtration device comprising a filter element, a filter case and a lid member. The lid member includes an engaging means. The filter element also includes another engaging means to engage with the engaging means of the lid member.

The present invention has been made in the light of the circumstances, and an object is to provide a filtration device that allows preventing use of a component other than a genuine product (so-called a component of a non-genuine product).

The technical object is solved by the subject-matter of claim <NUM>. Preferred embodiments of the present invention are the subject-matter of dependent claims.

According to the filtration device according to the present invention, in the state in which the lid member is attached to the first plate of the filter element, with the filter element inserted into the filter case, the second tubular portion having a substantially cylindrical shape and formed in the lid member is inserted into the first tubular portion having the substantially cylindrical shape and protruding toward the lid member. The lid member includes the ribs provided along the outer circumferential surface of the first tubular portion and provided radially outwardly of the second tubular portion and protruding in the same direction as the second tubular portion. The notches are provided between the ribs. The first projection formed to protrude outward in the radial direction on the first tubular portion is inserted into a corresponding one of the notches. In contrast to the component including the first projection and the notches (genuine product), in a component not including the first projection or the notches (so-called a non-genuine product), the first projection contact the notches, and therefore the filter case and the lid member cannot completely attached, and the filtration device cannot be used. By thus providing the first projection and the notches in the genuine product, prevention of use of the component other than the genuine product (so-called the component of the non-genuine product) is allowed.

Here, the filtration device may be configured as follows. The first tubular portion includes second projection protruding outward in the radial direction. The second projection are provided at positions different from the first projections in a circumferential direction. The first projection and the second projection are disposed uniformly in plan view. The notches are disposed uniformly in plan view. With the lid member attached to the first plate, the second projection is inserted into a corresponding one of the notches. By this configuration, the use of the component other than the genuine product can be reliably prevented.

Here, the filtration device may be configured as follows. A position of the first tubular portion overlaps with a position of the rib in plan view. A recessed portion is formed on the rib such that a part where the rib overlaps with the first tubular portion is cut out. With the lid member attached to the first plate, a bottom surface of the recessed portion is adj acent to a distal end of the first tubular portion. In this manner, in contrast to the genuine product including the recessed portion, in a non-genuine product not including the recessed portion, the distal end of the rib abuts on the distal end of the first tubular portion and therefore the filter element cannot be inserted up to the correct position and the filtration device cannot be used. This allows preventing the use of the component of the non-genuine product.

Here, the filtration device may be configured as follows. The first tubular portion includes a small-diameter portion provided on a distal end side and a large-diameter portion provided on a base side. The small-diameter portion has an outer diameter smaller than an outer diameter of the large-diameter portion. The recessed portion is formed on the rib such that a position of the rib overlaps with a position of the small-diameter portion and a part where the rib overlaps with the small-diameter portion is cut out in plan view. With the lid member attached to the first plate, the ribs are disposed along an outer circumferential surface of the small-diameter portion and distal ends of the ribs are adjacent to a planar portion formed between the small-diameter portion and the large-diameter portion. In contrast to the genuine product including the recessed portion, in a non-genuine product not including the recessed portion, the distal ends of the ribs abut on a distal end of the small-diameter portion and therefore the filter element cannot be inserted up to the correct position and the filtration device cannot be used. This allows preventing the use of the component of the non-genuine product.

Here, the filtration device may be configured as follows. The filter element includes an inner tube inserted into a hollow portion of the filter medium. The second plate has a hole into which the inner tube is inserted. The inner tube includes a flange portion and a protruding portion. The flange portion having a substantially circular plate shape is disposed on a lower side of the second plate. The protruding portion is formed so as to protrude upward from the flange portion on the flange. A second recessed portion into which the protruding portion is inserted is formed on a surface on a lower side of the second plate. In contrast to the genuine product thus including the protruding portion and the second recessed portion, in a non-genuine product not including the protruding portion or the second recessed portion, the filter element cannot be inserted up to the correct position and the filtration device cannot be used. By thus providing the protruding portion and the second recessed portion in the genuine product, the use of the component other than the genuine product can be prevented.

The present invention allows preventing the use of the component other than the genuine product (so-called the component of the non-genuine product).

Hereinafter, with reference to the drawings, detailed description will be made on embodiments of the present invention.

<FIG> is a perspective view illustrating an overview of a filtration device <NUM>. The filtration device <NUM> removes, for example, dust contained in a liquid, such as an oil and water, using a filter and mainly includes a filter case <NUM>, a lid member <NUM>, and a filter element <NUM> (see, for example, <FIG>).

The lid member <NUM> includes an inflow port <NUM> and an outflow port <NUM>. The inflow port <NUM> flows a liquid before filtration in an internal space formed by the filter case <NUM> and the lid member <NUM>. The outflow port <NUM> flows out a liquid after filtration.

An indicator <NUM> is provided on the lid member <NUM>. The indicator <NUM> measures a pressure difference inside the filter case <NUM> using a reed switch (not illustrated) provided inside the indicator <NUM> and indicates the measurement result by turning on/off a lamp (not illustrated). Note that the indication of the measurement result is not limited to the turning on/off of the lamp. For example, the measurement result may be displayed on a display unit (for example, a liquid crystal panel).

<FIG> is a cross-sectional view illustrating an overview of the filtration device <NUM>. The filter case <NUM> is a substantially bottomed cylindrical member made of metal or resin and has one end (here, a lower end) that is substantially closed and the open other end. The substantially closed lower end of the filter case <NUM> is a bottom surface <NUM>.

A hole <NUM> is formed in the bottom surface <NUM> of the filter case <NUM>, and a drain (not illustrated) is provided in the hole <NUM>. The drain may be omitted.

The filter case <NUM> has a substantially cylindrical side surface <NUM>. The side surface <NUM> has a lower end connected to the bottom surface <NUM>. An upper end of the side surface <NUM> is an open end <NUM>. An internal thread portion <NUM> is formed on an inner circumferential surface of the side surface <NUM> in the vicinity of the open end <NUM>.

The lid member <NUM> is a member having a substantially bottomed cylindrical shape and made of metal. The lid member <NUM> includes an attachment portion <NUM> having a substantially cylindrical shape formed to protrude from the bottom surface to a lower side (-z side). An external thread portion <NUM> is formed on an outer circumferential surface of the attachment portion <NUM>.

The open end <NUM> of the filter case <NUM> is attached to the lid member <NUM>. Screwing the external thread portion <NUM> into the internal thread portion <NUM> attaches the lid member <NUM> to the filter case <NUM>. The lid member <NUM> is thus provided so as to cover the open end <NUM> of the filter case <NUM>. Note that the lid member <NUM> is provided such that its bottom surface is located on the upper side (+z side).

Thus connecting the open end of the lid member <NUM> and an open end of the filter case <NUM> forms a space into which the filter element <NUM> is inserted is formed inside the filtration device <NUM>.

A sealing member (for example, an O-ring) (not illustrated) is provided between the filter case <NUM> and the lid member <NUM>. The sealing member provides sealing to avoid a liquid to leak outside from between the filter case <NUM> and the lid member <NUM>.

The lid member <NUM> includes a fitting cylinder <NUM> having a substantially cylindrical shape formed to protrude from the bottom surface to the lower side (-z side). The fitting cylinder <NUM> is formed inside the attachment portion <NUM>. The fitting cylinder <NUM> is inserted into an inside of a tubular portion 34c (described in detail later) of a plate <NUM> (described in detail later). The fitting cylinder <NUM> constitutes a structure for preventing imitation attachment (a first imitation attachment prevention structure, described in detail later).

The filter case <NUM> is internally includes the filter element <NUM> and an inner tube <NUM>. The filter element <NUM> mainly includes a filter medium <NUM> and plates <NUM>, <NUM> provided on both ends of the filter medium <NUM>.

When the lid member <NUM> is attached to the filter case <NUM>, the filter element <NUM> and the inner tube <NUM> are held in the internal space formed by the filter case <NUM> and the lid member <NUM>.

The inner tube <NUM> is a member having a substantially hollow cylindrical shape and formed of a material with high corrosion resistance (resin in the present embodiment). The inner tube <NUM> is provided inside the filter case <NUM> and inserted an inner circumferential surface of the filter medium <NUM>. The substantially cylindrical part inserted into the inner circumferential surface of the filter medium <NUM> is a tubular portion 31a. A large number of holes 31d through which hydraulic oil passes are formed on the entire surface of the tubular portion 31a.

The filter medium <NUM> has a substantially hollow cylindrical shape having a thickness in the radial direction thereof. The filter medium <NUM> is formed by pleating a sheet-like filter paper using, for example, synthetic resin and paper, and connecting both ends of the pleated filter paper to round in a cylindrical shape. The filter medium <NUM> is provided on the outer side of the inner tube <NUM>.

The plates <NUM>, <NUM> are substantially plate-shaped members, and are formed using a material with high corrosion resistance (resin in the present embodiment). The plate <NUM> is provided on the lower side of the filter medium <NUM>, and the plate <NUM> is provided on the upper side of filter medium <NUM>.

The plates <NUM>, <NUM> include plate-like portions 33a, 34a having a substantially circular plate shape that cover end surfaces of the filter medium <NUM>. Holes 33b, 34b into which the inner tube <NUM> is inserted are formed in the plate-like portions 33a, 34a, respectively. In plan view (as viewed in the z-direction), the holes 33b, 34b have a size substantially same as a size of a hollow portion of the filter medium <NUM>.

The inner tube <NUM> includes a flange portion 31b having a substantially circular plate shape disposed on a lower side of the plate-like portion 33a and a protruding portion 31c formed so as to protrude upward from the flange portion 31b. A recessed portion 33c into which the protruding portion 31c is inserted is formed on a surface on a lower side of the plate-like portion 33a. The protruding portion 31c and the recessed portion 33c constitute a structure for preventing imitation attachment (a second imitation attachment prevention structure, described in detail later).

The tubular portion 34c having a substantially cylindrical shape is formed on the plate-like portion 34a. The tubular portion 34c protrudes on the opposite side of the filter medium <NUM> when the plate <NUM> is provided on the filter medium <NUM>. In other words, the tubular portion 34c protrudes toward the lid member <NUM> with the filter element <NUM> inserted into the filter case <NUM>.

Projections 34d are formed in the vicinity of a distal end 34e of the tubular portion 34c. The projections 34d constitute a structure for preventing imitation attachment (the first imitation attachment prevention structure, described in detail later).

The fitting cylinder <NUM> is inserted into the tubular portion 34c. In the vicinity of the distal end 34e of the tubular portion 34c, an inner circumferential surface 34f opposed to the fitting cylinder <NUM> when the fitting cylinder <NUM> is inserted is provided. When the fitting cylinder <NUM> is inserted into the tubular portion 34c, a sealing member <NUM> provided on the inner circumferential surface 34f elastically deforms and closely contacts the fitting cylinder <NUM> and the tubular portion 34c. As a result, the filter element <NUM> is provided on the lid member <NUM>.

<FIG> is a partially enlarged view of the filtration device <NUM> and a partially cutaway view. A first imitation attachment prevention structure <NUM> mainly includes ribs 25a formed on the fitting cylinder <NUM> and the projections 34d formed on the tubular portion 34c.

<FIG> is a perspective view of the lid member <NUM>. A flange portion 25b having a substantially circular plate shape is provided in the vicinity of a lower end of the fitting cylinder <NUM> (see <FIG>) so as to protrude outward in the radial direction. A distal end side with respect to the flange portion 25b of the fitting cylinder <NUM> is an insertion portion 25c inserted into a hollow portion of the tubular portion 34c (see <FIG>).

A plurality of the ribs 25a substantially parallel to the insertion portion 25c are formed on the flange portion 25b. The rib 25a is a substantially plate-shaped member and protrudes in the same direction as the insertion portion 25c. Each of the plurality of ribs 25a are a part of a substantially-cylindrical-shaped rib and are separately provided. Between the adjacent ribs 25a and 25a are notches 25d into which the projections 34d are inserted. In plan view, the plurality of ribs 25a and notches 25d are disposed uniformly.

<FIG> is a perspective view of the filter element <NUM>. A plurality of the projections 34d having a substantially plate shape protruding outward in the radial direction are formed on the tubular portion 34c. Each of the plurality of projections 34d are a part of a flange having a substantially circular plate shape and are separately provided. In plan view, the plurality of projections 34d are disposed uniformly.

In the present embodiment, while the projections 34d are provided along the distal end 34e, the projections 34d only need to be provided in the vicinity of the distal end 34e. For example, the projections 34d may be provided slightly below the distal end 34e. However, it is desirable that a position in a height direction of the projection 34d overlaps with the inner circumferential surface 34f.

The description will now return to <FIG>. When the insertion portion 25c (see <FIG>) is inserted into the tubular portion 34c and the lid member <NUM> is attached to the plate <NUM>, the ribs 25a are provided along the outer circumferential surface of the tubular portion 34c. In addition, when the insertion portion 25c (see <FIG>) is inserted into the tubular portion 34c and the lid member <NUM> is attached to the plate <NUM>, the projection 34d is inserted between the rib 25a and the rib 25a.

By disposing the ribs 25a and the projections 34d in this manner, the projections 34d do not interfere with the ribs 25a, and the lid member <NUM> can be pushed to the plate <NUM> until the distal end 34e (see <FIG>) of the tubular portion 34c abuts on the flange portion 25b.

<FIG> is a cross-sectional perspective view of the filtration device <NUM> and a partially enlarged view. A second imitation attachment prevention structure <NUM> mainly includes the protruding portion 31c formed on the inner tube <NUM> and the recessed portion 33c formed on the plate <NUM>.

<FIG> is a cross-sectional perspective view of the filter case <NUM> and the inner tube <NUM> and a partially enlarged view. The inner tube <NUM> includes a protruding portion 31e formed so as to protrude downward (in the -z-direction) from the flange portion 31b having a substantially circular plate shape. When an external thread 31f formed on an outer circumferential surface of the protruding portion 31e is screwed into an internal thread portion 12a formed in the hole <NUM>, the inner tube <NUM> is attached to the filter case <NUM>. With the inner tube <NUM> attached to the filter case <NUM>, the flange portion 31b abuts on the bottom surface <NUM>.

The protruding portion 31c that protrudes upward (in the +z-direction) from the flange portion 31b is formed on the flange portion 31b. Here, the protruding portion 31c has a simple shape and is a rib having a substantially cylindrical shape for ease of manufacturing.

<FIG> is a perspective view of the filter element <NUM> and a partially enlarged view. The plate <NUM> includes a tubular portion 33d formed on a lower side of the plate-like portion 33a. The recessed portion 33c is formed in a surface 33e of the lower side of the tubular portion 33d. Here, the recessed portion 33c is a substantially circular groove.

The description will now return to <FIG>. The filter element <NUM> is inserted into the filter case <NUM> so that the inner tube <NUM> is inserted into the hollow portion of the filter medium <NUM>. Because the protruding portion 31c is inserted into the recessed portion 33c, the filter element <NUM> is inserted until the surface 33e abuts on an upper surface of the flange portion 31b.

When the surface 33e is inserted until abutting on the upper surface of the flange portion 31b, a sealing member <NUM> provided in the hole 33b elastically deforms and closely contacts an outer circumferential surface <NUM> of the inner tube <NUM> and an inner circumferential surface of the tubular portion 33d. As a result, the filter element <NUM> is provided to the inner tube <NUM>.

Next, an operation of the filtration device <NUM> will be described. The arrows in <FIG> indicate a flow of a liquid. The liquid that has flowed from the inflow port <NUM> is introduced between the filter case <NUM> and the filter element <NUM>. After that, the liquid passes through the filter medium <NUM> from outside to inside, and impurities in the liquid are removed in the process. The liquid that has passed through the inside of the filter medium <NUM> passes through the holes 31d formed in the inner tube <NUM> and flows out to the inside of the inner tube <NUM>.

The liquid after filtration flows out to the outside of the filtration device <NUM> from the inside of the inner tube <NUM> via the outflow port <NUM>. Note that between the filter element <NUM> and the inner tube <NUM>, and between the filter element <NUM> and the lid member <NUM> are liquid-tightly closed by the sealing members <NUM>, <NUM>, respectively. Therefore, the liquid before filtration does not penetrate into the inside of the inner tube <NUM>.

The filtration of the liquid gradually decreases a filtration capacity of the filter medium <NUM>. Thus, the filter element <NUM> is replaced periodically or as needed. A procedure of the replacement will be described below.

First, the external thread portion <NUM> and the internal thread portion <NUM> are unscrewed to disassemble the filter case <NUM> and the lid member <NUM>. As a result, the plate <NUM> of the filter element <NUM> is exposed. By pulling up the plate <NUM>, the filter element <NUM> is removed from the inner tube <NUM>. At this time, the use of the projections 34d as gripped portions facilitates handling of the filter element <NUM>.

After that, the new filter element <NUM> is then inserted into the filter case <NUM>. Because the protruding portion 31c is formed in the inner tube <NUM>, the insertion of the filter element <NUM> in which the recessed portion 33c is formed inserts the protruding portion 31c into the recessed portion 33c, and the filter element <NUM> is pushed until the surface 33e abuts on the upper surface of the flange portion 31b.

When the filter element <NUM> is inserted into the filter case <NUM>, the external thread portion <NUM> and the internal thread portion <NUM> are screwed to join the filter case <NUM> and the lid member <NUM> together. In the process of screwing the external thread portion <NUM> and the internal thread portion <NUM>, the fitting cylinder <NUM> is inserted into the tubular portion 34c, and the projection 34d is inserted between the rib 25a and the rib 25a. When the external thread portion <NUM> and the internal thread portion <NUM> continue to be screwed together, by pressing the projections 34d by the ribs 25a, the fitting cylinder <NUM> is inserted into the inside of the tubular portion 34c while the lid member <NUM> and the filter element <NUM> rotate with respect to the inner tube <NUM>.

Because the projection 34d is inserted into the notch 25d between the rib 25a and the rib 25a, the external thread portion <NUM> and the internal thread portion <NUM> can be screwed together until the distal end 34e of the tubular portion 34c abuts on the flange portion 25b. Thus, the replacement of the filter element <NUM> ends.

Here, assume a case in which a filter element as a non-genuine product other than the filter element <NUM>, which is a genuine product, is attached to the filter case <NUM> and the lid member <NUM>. For example, in a case where the recessed portion 33c is not formed on the filter element of the non-genuine product, the surface 33e abuts on the protruding portion 31c and the filter element of the non-genuine product cannot be inserted up to the correct position. As a result, the external thread portion <NUM> and the internal thread portion <NUM> cannot be screwed together, and the filtration device <NUM> cannot be used.

For example, in a case where a depth of the recessed portion 33c formed on the filter element of the non-genuine product is insufficient or in a case where the projections 34d are not formed on the filter element of the non-genuine product, the external thread portion <NUM> and the internal thread portion <NUM> can be screwed only up to the middle, and the filtration device <NUM> cannot be used.

For example, assume a case in which, instead of the projections 34d of the filter element <NUM> as the genuine product, a flange having a substantially circular plate shape is provided on the filter element as the non-genuine product. In a case where such a filter element of the non-genuine product is inserted into the filter case <NUM>, the rib 25a contacts the flange during the process of screwing the external thread portion <NUM> and the internal thread portion <NUM>, and the external thread portion <NUM> and the internal thread portion <NUM> cannot be screwed together, thereby failing to assemble the filtration device <NUM>. In addition, also in the case where the notches 25d are not formed on a lid member not a genuine product (a rib having a substantially cylindrical shape is formed), the rib having the substantially cylindrical shape contacts the projection 34d and the external thread portion <NUM> and the internal thread portion <NUM> cannot be screwed together, thereby failing to assemble the filtration device <NUM>.

According to the present embodiment, it is possible to reliably prevent the use of the filter element other than the filter element <NUM> as the genuine product, that is, the filter element of the non-genuine product.

Note that while the filtration device <NUM> includes the first imitation attachment prevention structure <NUM> and the second imitation attachment prevention structure <NUM> in the present embodiment, the filtration device <NUM> only needs to include the first imitation attachment prevention structure <NUM> or the second imitation attachment prevention structure <NUM>.

In addition, while the filtration device <NUM> includes the four ribs 25a and the four projections 34d in the present embodiment, at least one projection 34d only needs to be provided. In the case of one projection 34d, it is only necessary that the two ribs 25a are provided at positions where the projection 34d is sandwiched and the projection 34d is inserted into the notch 25d between the two ribs 25a. Additionally, in the case of one projection 34d, instead of the two ribs 25a, one rib having a substantially cylindrical shape with the notch 25d to which the projection 34d fits may be provided. However, to make manufacturing of the non-genuine product difficult and to reliably prevent the use of the component other than the genuine product, providing the plurality of ribs 25a, notches 25d, and projections 34d is preferred. Additionally, the plurality of ribs 25a, notches 25d, and projections 34d are preferably provided uniformly. For example, the six ribs 25a, the six notches 25d, and the six projections 34d may be provided at every approximately <NUM> degrees. In this manner, by providing the plurality of ribs 25a, notches 25d, and projections 34d and disposing these members uniformly, assembly properties can be improved while the use of the component other than the genuine product is prevented.

In the present embodiment, while the first imitation attachment prevention structure <NUM> includes the ribs 25a and the projections 34d, and the ribs 25a are provided along the outer circumferential surface of the tubular portion 34c, the configurations of the ribs 25a, the tubular portion 34c, and the projections 34d are not limited to these configurations.

<FIG> is a diagram illustrating an overview of a first imitation attachment prevention structure 50A included in a filtration device <NUM>. The first imitation attachment prevention structure 50A includes ribs 25a-<NUM>, a tubular portion 34c-<NUM>, and the projections 34d. A notch 25d-<NUM> into which the projection 34d is inserted is provided between the ribs 25a-<NUM> and the ribs 25a-<NUM>. The projections 34d are provided on a distal end of a small-diameter portion <NUM>. The small-diameter portion <NUM> is provided on a distal end side of the tubular portion 34c-<NUM>, and has an outer diameter smaller than that of a large-diameter portion 34i provided on a base side of the tubular portion 34c-<NUM>.

The tubular portion 34c-<NUM> has a planar portion <NUM>, and the planar portion <NUM> is formed between the small-diameter portion <NUM> and the large-diameter portion 34i. When a lid member 20A is attached to a plate 34A, the projections 34d are inserted into the notches 25d-<NUM>, the ribs 25a-<NUM> are provided along the outer circumferential surface of the small-diameter portion <NUM>, and distal ends of the ribs 25a-<NUM> are adjacent to the planar portion <NUM>.

<FIG> is a cross-sectional view on a surface P in <FIG>. <FIG> illustrates a state seen from a front side of the paper of <FIG>. In plan view, the position of the rib 25a-<NUM> overlaps with the position of the tubular portion 34c-<NUM>. Additionally, a recessed portion 25e is formed on the rib 25a-<NUM> such that the position of the rib 25e overlaps with the position of the small-diameter portion <NUM> and a part where the rib 25a-<NUM> overlaps with the small-diameter portion <NUM> is cut out in plan view. Thus, when the lid member 20A is attached to the plate 34A, a bottom surface 25f of the recessed portion 25e is adjacent to the distal end of the small-diameter portion <NUM>, and the lid member 20A is pushed to the plate 34A up to a position where the distal end of the rib 25a-<NUM> is adjacent to the planar portion <NUM>.

Here, assume a case where a non-genuine product in which the recessed portions 25e are not provided on the ribs 25a-<NUM> is attached to the filter case <NUM> (see <FIG>). When the recessed portion 25e is not provided, the distal end of the rib 25a-<NUM> abuts on the distal end of the small-diameter portion <NUM> and the lid member 20A cannot be pushed up to the position where the distal end of the rib 25a-<NUM> is adjacent to the planar portion <NUM>, and therefore the lid member 20A cannot be attached to the filter case <NUM>. In contrast, in the filtration device <NUM>, the ribs 25a-<NUM> and the tubular portion 34c-<NUM> are formed so that the positions of the ribs 25a-<NUM> and the position of the tubular portion 34c-<NUM> overlap in plan view, and the recessed portions 25e are provided such that the ribs 25a-<NUM> do not contact the small-diameter portion <NUM>. Thus, the lid member 20A can be pushed up to the position where the distal end of the rib 25a-<NUM> is adjacent to the planar portion <NUM>.

As described above, according to the present embodiment, the use of the filter element or the lid member of the non-genuine product can be reliably prevented. In addition, since the components are not increased, the assembly properties are not reduced.

Note that in the present embodiment, the second imitation attachment prevention structure <NUM> may be omitted. The filtration device <NUM> may only include the first imitation attachment prevention structure 50A or may include the first imitation attachment prevention structure 50A and the second imitation attachment prevention structure <NUM>.

While the second embodiment uses the tubular portion 34c-<NUM> with the small-diameter portion <NUM> formed on its distal end, the small-diameter portion <NUM> may be omitted. <FIG> is a diagram illustrating an overview of the modification in which the small-diameter portion <NUM> is not used. A recessed portion <NUM> is formed on a rib 25a-<NUM> such that a position of the rib 25a-<NUM> overlaps with the position of the tubular portion 34c and a part where the rib 25a-<NUM> overlaps with the tubular portion 34c is cut off in plan view. Thus, when a lid member 20B is attached to the plate <NUM>, a bottom surface <NUM> of the recessed portion <NUM> is adjacent to the distal end of the tubular portion 34c, and the lid member 20B is pushed to the plate <NUM> up to a position where the distal end of the rib 25a-<NUM> is adjacent to the plate-like portion 34a.

In contrast, assume a case where a non-genuine product in which the recessed portion <NUM> is not provided is attached to the filter case <NUM> (see <FIG>). In a case where the recessed portion <NUM> is not provided, the distal end of the rib 25a-<NUM> abuts on the distal end of the tubular portion 34c, and the lid member 20B cannot be pushed up to a position where the distal end of the rib 25a-<NUM> is adjacent to the plate-like portion 34a. As described above, in the present modification, the use of the filter element or the lid member of the non-genuine product can be reliably prevented, similarly to the second embodiment.

Note that, in the second embodiment, the shape is more complicated than that of the present modification. Thus, when the lid member or the filter element of the non-genuine product is processed and attempted to be attached to the filter case of the genuine product, processing the non-genuine product is difficult. Therefore, compared to the present modification, the second embodiment can more reliably prevent the use of the filter element or the lid member of the non-genuine product.

The reference embodiment, which is not part of the present invention, has a configuration in which a third imitation attachment prevention structure <NUM> is provided instead of the first imitation attachment prevention structure <NUM>. <FIG> is a diagram illustrating an overview of the third imitation attachment prevention structure <NUM> included in a filtration device <NUM>.

A difference between the third imitation attachment prevention structure <NUM> and the first imitation attachment prevention structure 50A is presence/absence of the notches 25d-<NUM>. The third imitation attachment prevention structure <NUM> includes the rib 25a-<NUM> and a tubular portion 34c-<NUM>. The rib 25a-<NUM> is a substantially cylindrical rib substantially parallel to the insertion portion 25c (see <FIG>) and similar to the rib 25a-<NUM> except that notches are not formed. The tubular portion 34c-<NUM> is the similar to the tubular portion 34c-<NUM> except that the projections 34d are not formed. The cross-sectional shape of the surface P in <FIG> is similar to that of <FIG>.

According to the reference embodiment, the filtration device <NUM> including the third imitation attachment prevention structure <NUM> avoids the external thread portion <NUM> and the internal thread portion <NUM> (see <FIG>) to be screwed together even when the filter element or the lid member of the non-genuine product is attempted to be attached to the filter case <NUM>. As a result, the use of the filter element or the lid member of the non-genuine product can be reliably prevented.

Note that the filtration device <NUM> may include the second imitation attachment prevention structure <NUM> in addition to the third imitation attachment prevention structure <NUM>. The filtration device <NUM> including the second imitation attachment prevention structure <NUM> and the third imitation attachment prevention structure <NUM> allows further reliably preventing the use of the filter element or the lid member of the non-genuine product. A cross-sectional shape of the surface P in <FIG> may be similar to that of <FIG>.

Claim 1:
A filtration device (<NUM>; <NUM>) comprising:
a filter element (<NUM>) that includes a filter medium (<NUM>), a first plate (<NUM>), and a second plate (<NUM>), the filter medium (<NUM>) having a hollow cylindrical shape with openings at both ends, the first plate (<NUM>) covering the opening at an upper end of the filter medium (<NUM>), the second plate (<NUM>) covering the opening at a lower end of the filter medium (<NUM>);
a filter case (<NUM>) having a bottomed substantially cylindrical shape that is internally provided with the filter element (<NUM>); and
a lid member (<NUM>) covering an opening at an upper end of the filter case (<NUM>), wherein
the first plate (<NUM>) includes a first tubular portion (34c; 34c-<NUM>) having a substantially cylindrical shape, and the first tubular portion (34c; 34c-<NUM>) protrudes toward the lid member (<NUM>) with the filter element (<NUM>) inserted into the filter case (<NUM>),
the lid member (<NUM>) includes ribs (25a; 25a-<NUM>; 25a-<NUM>), and
the first tubular portion (34c; 34c-<NUM>) includes a first projection (34d) protruding outward in a radial direction, characterised in that
the lid member (<NUM>) further includes a second tubular portion (25c) having a substantially cylindrical shape,
the ribs (25a; 25a-<NUM>; 25a-<NUM>) are provided radially outwardly of the second tubular portion (25c) and protrude in the same direction as the second tubular portion (25c),
the second tubular portion (25c) is configured to be inserted into a hollow portion of the first tubular portion (34c; 34c-<NUM>),
when the second tubular portion (25c) is inserted into the first tubular portion (34c; 34c-<NUM>), the ribs (25a; 25a-<NUM>; 25a-<NUM>) are provided along an outer circumferential surface of the first tubular portion (34c; 34c-<NUM>),
notches (25d; 25d-<NUM>) are provided between the ribs (25a; 25a-<NUM>; 25a-<NUM>), and
with the lid member (<NUM>) attached to the first plate (<NUM>), the second tubular portion (25c) is inserted into the first tubular portion (34c; 34c-<NUM>) and the first projection (34d) is inserted into a corresponding one of the notches (25d; 25d-<NUM>) between the ribs (25a; 25a-<NUM>; 25a-<NUM>).