SUCTION STRAINER

A filter section includes a filter having a cylindrical shape formed from a pleated plate; an attachment section having a cylindrical shape provided on a side surface of the tank, the attachment section with one end of the filtration section; a plate covering an end of the filtration section on a side not provided with the attachment section; and a baffle plate provided adjacent to the filtration section. The filtration section is provided along a horizontal direction, and the filtration section and the plate are provided inside the tank. The baffle plate includes at least one of a first baffle plate provided inside the pleated filter and a second baffle plate provided outside the pleated filter. The first baffle plate is disposed at least above a central axis of the filtration section, and the second baffle plate is disposed at least below the central axis.

TECHNICAL FIELD

The present invention relates to a suction strainer.

BACKGROUND ART

PTL 1 discloses a suction filter provided with a cover and a valve. The cover is provided at the upper end surface of a cylindrical first filtration section so as to cover the entirety of the upper side of the first filtration section, and the valve is provided at a hollow part of the first filtration section on the lower side of the cover. In the valve, a first valve that is movable along a bar-shaped member is switched between a closed state of closing a hole of the cover and an open state of not closing the hole.

CITATION LIST

Patent Literature

In the invention described in PTL 1, since the axis of the cylindrical filtration section is along the vertical direction, which is so-called vertical placement, bubbles adhering to the filtration section float inside oil stored in a tank, and the bubbles are released to the outside of the suction filter via a valve. However, due to the restriction of the installation position, a case where the filtration section is provided along a horizontal direction, which is so-called horizontal placement, has been increasing in recent years, and in such a case, bubbles are less likely to float as compared with the case of the vertical placement.

FIG.15is views schematically illustrating behavior of bubbles adhering to a filtration section150, where (A) is an example of vertical placement and (B) is an example of horizontal placement. In the case of vertical placement, the bubbles adhering to the filtration section150float upward along the filtration section150(see arrows inFIG.15(A)). On the other hand, in the case of the horizontal placement, the bubbles adhering to the upper half of the filtration section150can float upward (see arrows inFIG.15(B)), but the bubbles adhering to the lower half of the filtration section150are blocked by the filtration section150and cannot float upward. As a result, the bubbles adhering to the lower half of the filtration section150pass through the filtration section150, and as a result, there are possibilities of break down due to the pump suctioning the air and damage of a component and the like resulting from the bubbles bursting inside the hydraulic circuit or the like.

SUMMARY OF INVENTION

One or more embodiment of the present invention is to provide a suction strainer that can prevent bubbles from flowing out when a filtration section is provided along a horizontal direction.

A suction strainer according to one or more embodiment of the present invention is, for example, a suction strainer provided in a tank in which liquid is stored, the suction strainer including: a filtration section having a cylindrical shape including a pleated filter having a cylindrical shape formed by bending a thin plate (plate shaped filter or filter plate) into a pleated shape; an attachment section having a cylindrical shape provided on a side surface of the tank, the attachment section being provided with one end of the filtration section; a plate (cover plate) covering an end of the filtration section on a side not provided with the attachment section; and a baffle plate including at least one of a first baffle plate provided inside the pleated filter and a second baffle plate provided outside the pleated filter, in which the filtration section is provided along a horizontal direction, the filtration section and the plate are provided inside the tank, at least a part of the first baffle plate is disposed above a central axis of the filtration section, and at least a part of the second baffle plate is disposed below the central axis.

According to one or more embodiment of the suction strainer to the present invention, the filtration section provided along the horizontal direction and the plate covering one end of the filtration section are provided inside the tank in which the liquid is stored. In addition, the suction strainer includes at least one of the first baffle plate provided inside the pleated filter included in the filtration section and the second baffle plate provided outside the pleated filter, at least a part of the first baffle plate is disposed above the central axis of the filtration section, and at least a part of the second baffle plate is disposed below the central axis of the filtration section. This can prevent outflow of bubbles from the suction strainer. As a result, inflow of bubbles into the pump provided downstream of the suction strainer is prevented.

The first baffle plate may include an air reservoir section having a cylindrical shape with one end provided in the attachment section, and a radius of the air reservoir section may be large on the attachment section side and may gradually decrease toward the plate (the air reservoir section may taper toward the plate). This applies an upward force to the bubbles in contact with the air reservoir section, and the bubbles are less likely to flow into the hollow portion of the attachment section. In addition, since the air reservoir section has a cylindrical shape, more bubbles can be blocked by the air reservoir section.

The first baffle plate may have a cross-sectional shape that is an arc shape when taken along a first plane orthogonal to the central axis, and include an air reservoir section intersecting a line segment connecting an upper end portion of the filtration section and the central axis, the air reservoir section may have one end provided in the attachment section, and a radius of the air reservoir section may be large on the attachment section side and may gradually decrease toward the plate (the air reservoir section may taper toward the plate). This applies an upward force to the bubbles in contact with the air reservoir section, and the bubbles are less likely to flow into the hollow portion of the attachment section.

The first baffle plate may include an upper cover having a cross-sectional shape that is an arc shape when taken along a first plane orthogonal to the central axis, and provided at a position intersecting a line segment connecting an upper end portion of the filtration section and the central axis, and the upper cover may be provided on the plate side relative to the air reservoir section (an end of the upper cover is located closer to the cover plate than the air reservoir section). This allows more bubbles to be stored in a space above the air reservoir section, and as a result, bubbles flowing out of the suction strainer can be further reduced.

The second baffle plate may be a lower cover having a cross-sectional shape that is an arc shape when taken along a first plane orthogonal to the central axis, and provided at a position intersecting a line segment connecting a lower end portion of the filtration section and the central axis. This blocks the bubbles by the lower cover, and the bubbles hardly flow into the hollow portion of the filtration section.

The pleated filter may include a first pleated filter having a cylindrical shape and a second pleated filter having a cylindrical shape provided inside the first pleated filter, the first baffle plate may be provided inside the second pleated filter, and the second baffle plate may be provided outside the second pleated filter. This can prevent outflow of bubbles from the suction strainer also in a case of including two pleated filters.

The attachment section may be provided with an air vent hole allowing a hollow portion of the attachment section and an external space of the attachment section to communicate with each other, and the air vent hole may be provided with a float movably (accommodates the float to be movable) between a position where the float closes the air vent hole and a position where the float opens the air vent hole. This can discharge bubbles through the air vent hole.

A cover having a cylindrical shape with one end provided on the attachment section and the other end provided on the plate may be included, the cover may be provided along a horizontal direction, and a plurality of holes may be provided in a belt-shaped region along a horizontal direction positioned in a vicinity of a lower end of the cover. This can reduce the number of bubbles hitting the filtration section.

According to one or more embodiment of the present invention, it is possible to prevent outflow of bubbles from the suction strainer provided with the filtration section along the horizontal direction.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are elaborated below with reference to the accompanying drawings.

First Embodiment

FIG.1is a schematic diagram illustrating a hydraulic circuit110including a suction strainer1according to an embodiment of the present invention. InFIG.1, hatching indicating a cross section is omitted.

The tank100is installed in a work machine (e.g., a hydraulic apparatus) not illustrated in the drawing. The tank100is a tank for storing the hydraulic fluid and is provided in a hydraulic circuit110of the hydraulic fluid to be supplied to the hydraulic apparatus. Note that the component provided in the tank100is not limited to the hydraulic circuit, and the liquid stored in the tank100is also not limited to the hydraulic fluid.

The tank100has a box shape that is hollow inside, for example. The tank100mainly includes inside the suction strainer1and a return filter (omitted in the drawing).

In the hydraulic circuit110, the hydraulic fluid is introduced to the tank100through a hydraulic apparatus not illustrated in the drawing. In the tank100, an inlet (omitted in the drawing) that allows the hydraulic fluid to flow into the tank100is formed. The hydraulic fluid having entered from the inlet is guided to the return filter. The hydraulic fluid is filtered by the return filter, and stored in the tank100.

In the vicinity of the lower end portion of a side surface100bof the tank100(in the present embodiment, a position in the vicinity of a bottom surface100ain the side surface of the tank100), an outlet100cthat allows the hydraulic fluid inside the tank100to flow out to a hydraulic pump103is formed. The outlet100cis provided with the suction strainer1. The suction strainer1has a cylindrical shape and is provided along the horizontal direction.

The suction strainer1is provided with a suction pipe101extending from the outer side of the tank100to the suction port of the hydraulic pump103. The hydraulic fluid stored in the tank100is suctioned by the hydraulic pump103, carried to the suction pipe101through the suction strainer1, and supplied to the hydraulic apparatus again.

Note that the outlet100cand the suction strainer1need only to be provided at the side surface100bof the tank100, and the positions of the outlet100cand the suction strainer1are not limited to the positions illustrated inFIG.1.

FIG.2is a schematic diagram illustrating the suction strainer1and a tank100. In the following description, the extending direction of the suction strainer1(the extending direction of a central axis ax of the suction strainer1) is the x direction, and the vertical direction is the z direction (vertically upward is the +z direction). In addition, the direction orthogonal to the x direction and the z direction is the y direction.

The suction strainer1mainly includes a filtration section10, an attachment section20, a plate30, a cover40, floats51and52, a baffle plate61, and an attachment section70. The attachment section20is provided on a side surface100bof the tank100, and the attachment section70is provided on a side surface100dof the tank100.

The attachment section70includes a plate-shaped portion71and a bar-shaped member72. When the plate-shaped portion71is attached to the side surface100d, the plate30attached to the bar-shaped member72is pushed in a −x direction, whereby the suction strainer1is provided inside the tank100.

FIG.3is a cross-sectional view schematically illustrating the suction strainer1.FIG.3partially omits hatching indicating a cross section.

The filtration section10mainly includes pleated filters11and12and inner cylinders13and14. The inner cylinders13and14are provided inside the pleated filters11and12, respectively.

The pleated filters11and12are members that filter a hydraulic fluid, and have a cylindrical shape (here, a circular cylindrical shape). The heights of the pleated filters11and12are substantially the same. The pleated filters11and12are formed by pleating a sheet-like thin plate having holes formed in substantially the entire area, connecting both ends of the pleated thin plate, and rounding the pleated thin plate into a cylindrical shape. Thus, the pleated filters11and12are formed in a substantially circular cylindrical pleated shape. Note that in the present embodiment, the pleated filter12is formed of a wire mesh made of fine metal (e.g., stainless steel) in which thin wires are knitted in a mesh shape, but filter paper using synthetic resin, paper, or the like may be used.

The diameter of the pleated filter12(corresponding to the second pleated filter of the present invention) is smaller than the diameter of the pleated filter11(corresponding to the first pleated filter of the present invention), and the pleated filter12is provided inside the pleated filter11.

The inner cylinders13and14are members having a cylindrical shape (here, a circular cylindrical shape) having openings at both ends, and are formed using a material having high corrosion resistance (e.g., stainless steel). The heights of the inner cylinders13and14are substantially the same as the heights of the pleated filters11and12. The diameter of the inner cylinder13is smaller than a diameter of the pleated filter11, and the inner cylinder13is provided inside the pleated filter11. In addition, the diameter of the inner cylinder14is smaller than the diameter of the pleated filter12, and the inner cylinder14is provided inside the pleated filter12.

Holes13aand14athrough which the hydraulic fluid passes are formed substantially entirely in the inner cylinders13and14. The hydraulic fluid having passed through the pleated filter11passes through the hole13aand flows into the inner cylinder13. The hydraulic fluid flowing into the inner cylinder13passes through the pleated filter12, passes through the hole14a, and flows into the inner cylinder14.

The attachment section20is provided at one (−x side) end of the filtration section10, and the plate30is provided at the other (+x side) end. The attachment section20and the plate30are formed using a material (resin or metal) having high corrosion resistance.

The attachment section20has a cylindrical shape as a whole and is provided on the side surface100b. The attachment section20is provided with one (−x side) end of the filtration section10.

The attachment section20mainly includes a first attachment section21having a cylindrical shape provided on the side surface100b(seeFIG.2) and a second attachment section22having a cylindrical shape attached with the filtration section10.

The first attachment section21has a cylindrical portion21ato be inserted into the outlet100cand a flange portion21babutting on the side surface100b. A part of the cylindrical portion21aand the flange portion21bare provided outside the tank100.

The second attachment section22is provided in the first attachment section21, and includes a cylindrical portion22ainto which the cylindrical portion21ais inserted, and a plate-shaped portion22bprovided with the filtration section10. The second attachment section22is provided inside the tank100.

When the plate-shaped portion71(not illustrated inFIG.3) is attached to the side surface100d, the plate30, that is, the second attachment section22is pushed in the −x direction by the bar-shaped member72. This integrates the first attachment section21and the second attachment section22in a state where the end on the −x side of the cylindrical portion22aabuts on the side surface100band the cylindrical portion21ais inserted into a hollow portion of the cylindrical portion22a.

The cylindrical portion21ais inserted into the cylindrical portion22a, and an elastic member55(e.g., an O-ring) is provided between the cylindrical portion21aand the cylindrical portion22a, thereby integrating a hollow portion21cof the cylindrical portion21aand a hollow portion22eof the cylindrical portion22a. The hollow portion of the attachment section20, that is, the hollow portion21cand the hollow portion22eallow a hollow portion (space S3) of the filtration section10and the outside of the tank100(the inside of the suction pipe101) to communicate with each other.

The plate-shaped portion22bhas recess portions22cand22d. The recess portion22cis provided with the pleated filter11and the inner cylinder13, and the recess portion22dis provided with the pleated filter12and the inner cylinder14. Due to this, the attachment section20is provided with the filtration section10, and the filtration section10is extended along the horizontal direction.

The plate-shaped portion22bis provided with an air vent hole22f. The air vent hole22fis provided at a vertically upper end of the plate-shaped portion22b. The air vent hole22fallows the hollow portion22eand an external space (here, space S1) of attachment section20to communicate with each other. Here, the space S1is a space between the filtration section10and the attachment section20, and the cover40.

The float51is provided at an upper end of the air vent hole22f. The float51is movable in an up-down direction (z direction) between a position where the float51closes the air vent hole22fand a position where the float51opens the air vent hole22f. When bubbles flowing into the air vent hole22ffrom the hollow portion of the attachment section22or the suction pipe101flow into the air vent hole22f, grow in the air vent hole22f, and push up the float51in the +z direction, the air vent hole22fis opened. This can discharge the air stored in the hollow portion of the attachment section20and the suction pipe101to the space S1via the air vent hole22f.

The cover40is a cylindrical member and is extended along the horizontal direction. A belt-shaped region along the horizontal direction positioned in a vicinity of a lower end of the cover40is provided with a plurality of holes40a. Note that the cover40is not essential.

The cover40has one end provided on the side surface100b, and the other end provided on the plate30. That is, the plate30covers ends (openings) of the filtration section10and the cover40. Due to this, the hydraulic fluid flows into the space S1from the hole40aand flows into a space S2and the space S3from the filtration section10. Here, the space S2is a space between the pleated filter11and the pleated filter12.

The cover40is provided with a hole not illustrated, and this hole is provided with a float52. The float52is movable in the up-down direction (z direction) between a position where the float52closes the hole and a position where the float52opens the hole.

The baffle plate61(corresponding to the first baffle plate of the present invention) is provided inside the filtration section10. The baffle plate61has a cylindrical shape as a whole, and has one end provided in the attachment section20. The baffle plate61mainly includes an air reservoir section61ahaving a cylindrical shape and an extension cylinder61bhaving a cylindrical shape provided in the air reservoir section61a. The radius of the air reservoir section61ais large on the attachment section20side, and the radius gradually decreases toward the plate30. The radius of the extension cylinder61bis the same as the minimum radius of the air reservoir section61a. Note that the extension cylinder61bis not essential.

Next, the function of the suction strainer1configured as described above will be described with reference toFIG.3. After the suction strainer1is horizontally attached to the tank100, the hydraulic fluid is stored in the tank100.

Since the attachment section20is provided at one end of the filtration section10and the plate30is provided at the other end, when suctioned by the hydraulic pump103(not illustrated inFIG.3) as indicated by hollow arrow inFIG.3, the hydraulic fluid stored in the tank100is suctioned into the space S1from the outside of the cover40through the hole40a, is suctioned into the space S2from the space S1through the pleated filter11and the inner cylinder13, is suctioned into the space S3from the space S2through the pleated filter12and the inner cylinder14, and flows out from the space S3to the suction pipe101through the hollow portion21cand the hollow portion22e.

Since the hydraulic fluid is sucked by the hydraulic pump103, the floats51and52are pulled in the −z direction together with the hydraulic fluid, the float51abuts on the plate-shaped portion22band closes the air vent hole22f, and the float52closes the hole of the cover40. Due to this, the hydraulic fluid does not flow into the space S3from portions other than the hole40aand the filtration section10.

When the hydraulic fluid is suctioned into the space S3, bubbles V1contained in the hydraulic fluid are also suctioned into the filtration section10together with the hydraulic fluid. The bubbles V1flow in the +z direction and the −x direction along the flow of the hydraulic fluid (see dotted arrows (hatched) inFIG.3) and abut on the baffle plate61. Then, the bubbles V1accumulate in a space between the baffle plate61(air reservoir section61a) and the filtration section10and above (+z side) the baffle plate61, and grow into large bubbles V2.

When the hydraulic pump103(not illustrated inFIG.3) stops, the flow of the hydraulic fluid stops. As a result, the bubbles V2accumulated above the baffle plate61are discharged to the space S1via the filtration section10.

When the bubbles V2are discharged in the space S1, grow, and push up the float52in the +z direction, the holes of the cover40are opened, and air is released from the space S1to the outside of the suction strainer1.

According to the present embodiment, the bubbles V1flowing into the space S3can be prevented from flowing out from the suction strainer1provided along the horizontal direction by retaining the bubbles V2in the space S3by the baffle plate61. As a result, accumulation of bubbles in the suction pipe101and defects due to the pump suctioning the air can be prevented. In addition, damage of a component and the like resulting from the air bubbles bursting inside the hydraulic circuit or the like, which causes a temperature and a pressure of the hydraulic fluid to temporarily increase to a significant degree, can be prevented.

In addition, according to the present embodiment, since the air reservoir section61ahaving a radius large on the attachment section20side, and the radius gradually decreases toward the plate30is included, an upward force is applied to the bubbles V2abutting on the air reservoir section61a, and the bubbles V2are less likely to flow into the hollow portion of the attachment section20.

According to the present embodiment, even if bubbles accumulate in the suction pipe101, the bubbles can be discharged through the air vent hole22f.

In addition, according to the present embodiment, since the baffle plate61has a cylindrical shape, even if the bubbles V1flow in the −x direction before floating in the +z direction, the bubbles V1are blocked by the baffle plate61, and the bubbles V2can be formed on the upper side of the baffle plate61. Therefore, outflow of bubbles from the suction strainer1can be prevented.

In addition, according to the present embodiment, since the cover40in which the plurality of holes40aare formed is provided in the belt-shaped region along the horizontal direction positioned in the vicinity of the lower end, the bubbles formed when flowing into the tank from the return filter hardly hit the filtration section10. This reduces the number of bubbles V1hitting the filtration section10, and can reduce inflow of the bubbles V1into the space S3.

Note that in the present embodiment, the baffle plate61has a cylindrical shape, but the baffle plate61is not limited to a cylindrical shape. The baffle plate may be disposed at least above the central axis ax of the filtration section10.FIG.4is a schematic diagram illustrating a suction strainer1A having a baffle plate61A having a semicircular shape in cross-sectional view. Note thatFIG.4partially omits hatching indicating a cross section.

The difference between the suction strainer1A and the suction strainer1is only the baffle plate61A. The baffle plate61A (corresponding to the first baffle plate of the present invention) is provided inside the filtration section10. The baffle plate61A has a semicircular shape in cross-sectional view when taken along a plane (plane parallel to a yz plane, corresponding to the first plane of the present invention) orthogonal to the central axis ax. That is, the baffle plate61A may be disposed at least above the central axis ax of the filtration section10, and a part of the baffle plate61A may be disposed at the same height as the central axis ax or may be disposed below the central axis ax.

The baffle plate61A includes an air reservoir section61cand an extension portion61dprovided in the air reservoir section61c. The air reservoir section61cis a half on the +z side of the air reservoir section61a, and is inclined such that the radius is large on the attachment section20side and the radius gradually decreases toward the plate30. The extension portion61dis a half on the +z-side of the extension cylinder61b. The radius of the extension portion61dis the same as the minimum radius of the air reservoir section61a. The air reservoir section61cand the extension portion61dintersect a line segment connecting the upper end portion of the filtration section10and the central axis ax. Note that the extension portion61dis not essential.

Note that the cross-sectional shape of the baffle plate61A when taken along a plane orthogonal to the central axis ax is not limited to a semicircular shape, and may be an arc shape. That is, the baffle plate61A may be a part on the +z side of the baffle plate61, and the baffle plate61A may intersect the line segment connecting the upper end portion of the filtration section10and the central axis ax.

This can prevent the bubbles V1flowing into the space S3from flowing out from the suction strainer1A by retaining the bubbles V2in the space S3by the baffle plate61A.

Second Embodiment

In the first embodiment of the present invention, the filtration section10includes the two pleated filters11and12, but the number of pleated filters included in the filtration section10is not limited to this.

The second embodiment of the present invention is a form in which the filtration section includes one pleated filter. Below, description is given of a suction strainer2according to the second embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

FIG.5is a cross-sectional view schematically illustrating a suction strainer2. InFIG.5, hatching for indicating a cross section is omitted.

The suction strainer2mainly includes a filtration section10A, an attachment section20A, a plate30A, a float53, and the baffle plate61. The attachment section20A is provided on the side surface100b(not illustrated inFIG.5) of the tank100(not illustrated inFIG.5).

The filtration section10A includes the pleated filter12and the inner cylinder14. The attachment section20A is provided at one end (−z side) of the filtration section10A, and the plate30A is provided at the other end (+z side). The attachment section20A and the plate30A cover the ends of the filtration section10A, respectively.

The attachment section20A mainly includes a cylindrical portion20ainto which the suction pipe101(not illustrated inFIG.5) is inserted, a flange portion20babutting on the side surface100b, an attachment section20dattached with the filtration section10A, and a cylindrical portion20fbetween the flange portion20band the attachment section20d. The cylindrical portion20fis inserted into the outlet100c, and the attachment section20dis provided inside the tank100.

The attachment section20dincludes a recess portion20einto which the filtration section10A is inserted. When the recess portion20eis provided with the filtration section10A, the filtration section10A is provided in the tank100along the horizontal direction (here, x direction).

The cylindrical portion20ais provided with an air vent hole20g. The air vent hole20gis provided at a vertically upper end of the cylindrical portion20a. The air vent hole20gallows a hollow portion20cof the cylindrical portion20aand an external space of cylindrical portion20ato communicate with each other.

The float53is provided at an upper end of the air vent hole20g. The float53is movable in the up-down direction (z direction) between a position where the float53closes the air vent hole20gand a position where the float53opens the air vent hole20g. When bubbles flowing into the air vent hole20gfrom the hollow portion20cor the suction pipe101(not illustrated inFIG.5) flow into the air vent hole20g, grow in the air vent hole20g, and push up the float53in the +z direction, the air vent hole20gis opened. This can discharge, to the outside of the attachment section20A via the air vent hole20g, the air stored in the hollow portion of the attachment section20and the suction pipe101.

The baffle plate61is disposed inside the filtration section10A. One end of the baffle plate61is provided in the attachment section20A.

Next, the function of the suction strainer2configured as described above will be described. After the suction strainer2is horizontally attached to the tank100, the hydraulic fluid is stored in the tank100.

Since the attachment section20A is provided at one end of the filtration section10A and the plate30A is provided at the other end, when suctioned by the hydraulic pump103(not illustrated inFIG.5), the hydraulic fluid stored in the tank100is suctioned into the space S3through the pleated filter12and the inner cylinder14, and flows out from the space S3to the suction pipe101through the hollow portion20c. Since the hydraulic fluid is sucked by the hydraulic pump103, the float53is pulled in the −z direction together with the hydraulic fluid, and the float53closes the air vent hole20g. Due to this, the hydraulic fluid does not flow into the space S3from portions other than the filtration section10A.

When the hydraulic fluid is suctioned into the space S3, the bubbles V1contained in the hydraulic fluid are also suctioned into the filtration section10together with the hydraulic fluid. The bubbles V1flow in the +z direction and the −x direction along the flow of the hydraulic fluid and abut on the baffle plate61. Then, the bubbles V1accumulate in a space above (+z side) the baffle plate61, and grow into the large bubbles V2. Due to this, the bubbles V2hardly flow out to the hollow portion20c.

When the hydraulic pump103stops, the flow of the hydraulic fluid stops. As a result, the bubbles V2accumulated above the baffle plate61are discharged to the space S1via the filtration section10A.

According to the present embodiment, the bubbles V1flowing into the space S3can be prevented from flowing out from the suction strainer2provided along the horizontal direction by retaining the bubbles V2in the space S3by the baffle plate61.

Third Embodiment

In the first embodiment of the present invention, the baffle plate61includes the air reservoir section61aand the extension cylinder61b, but the form of the baffle plate is not limited to this. The third embodiment of the present invention is a form in which the baffle plate includes an upper cover. A suction strainer3according to the third embodiment will be described below. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

FIG.6is schematic diagrams illustrating a suction strainer3, where (A) is a cross-sectional view and (B) is a cross-sectional view of the suction strainer3taken along plane A-A.FIG.6partially omits hatching indicating a cross section.

The suction strainer3mainly includes the filtration section10, the attachment section20, the plate30, the cover40, the floats51and52, a baffle plate61B, and the attachment section70(partially not illustrated inFIG.6).

The baffle plate61B (corresponding to the first baffle plate of the present invention) is provided inside the filtration section10. The baffle plate61B has one end provided in the attachment section20. The baffle plate61B mainly includes the air reservoir section61ahaving a cylindrical shape, the extension cylinder61bhaving a cylindrical shape, and an upper cover61e.

The upper cover61eis provided on the plate30more than the air reservoir section61a. In the present embodiment, one end of the upper cover61eis provided in the extension cylinder61b, but when the extension cylinder61bis not provided, the upper cover61emay be provided in the air reservoir section61a.

The upper cover61ehas a cross-sectional shape that is an arc shape when taken along a plane (A-A cross section) orthogonal to the central axis ax. In the present embodiment, a central angle θ1of the upper cover61eis approximately 90 degrees in the A-A cross section. In addition, the upper cover61eis provided at a position intersecting a line segment connecting the upper end portion of the filtration section10and the central axis ax when taken along a plane (A-A cross section) orthogonal to the central axis ax.

Next, the function of the suction strainer3configured as described above will be described. After the suction strainer3is horizontally attached to the tank100, the hydraulic fluid is stored in the tank100.

Also regarding the suction strainer3, similarly to the suction strainer1, when suctioned by the hydraulic pump103(not illustrated inFIG.6), the hydraulic fluid stored in the tank100is suctioned into the space S3from the outside of the cover40via the hole40aand the filtration section10, and flows out from the space S3to the suction pipe101via the hollow portion21cand the hollow portion22e. In addition, the floats51and52are pulled in the −z direction together with the hydraulic fluid, the float51closes the air vent hole22f, and the float52closes the hole of the cover40. Due to this, the hydraulic fluid does not flow into the space S3from portions other than the hole40aand the filtration section10.

The bubbles V1contained in the hydraulic fluid are also suctioned into the space S3together with the hydraulic fluid. The bubbles V1flowing into the space S3from below the filtration section10flow in the +z direction and the −x direction along the flow of the hydraulic fluid, and abut on the air reservoir section61a.

The bubbles V1contained in the hydraulic fluid flowing into the space S2and the space S3from above or obliquely above the filtration section10hit the upper cover61e, flow in the −x direction along the upper cover61e, and abut on the air reservoir section61a. Then, the bubbles V1accumulate in a space above the air reservoir section61a, and grow into the large bubbles V2.

The bubbles V2accumulated above the baffle plate61B are discharged to the space S1via the filtration section10when the hydraulic pump103(not illustrated inFIG.6) stops. When the bubbles V2are discharged in the space S1, grow, and push up the float52in the +z direction, the holes of the cover40are opened, and air is released from the space S1to the outside of the suction strainer3.

According to the present embodiment, the bubbles V1flowing into the space S3can be prevented from flowing out from the suction strainer3provided along the horizontal direction by retaining the bubbles V2in the space S3by the baffle plate61B. In addition, by providing the upper cover61e, more bubbles V1can be stored in the space above the air reservoir section61a, and as a result, bubbles flowing out from the suction strainer3can be further reduced.

Note that in the present embodiment, the central angle θ1of the upper cover61eis approximately 90 degrees in the A-A cross section, but the central angle of the upper cover is not limited to this.FIG.7is schematic diagrams illustrating a suction strainer3A having a baffle plate61C according to a modification, where (A) is a cross-sectional view and (B) is a cross-sectional view of the suction strainer3A taken along plane B-B. Note thatFIG.7partially omits hatching indicating a cross section.

The difference between the suction strainer3A and the suction strainer3is only the baffle plate61C. The baffle plate61C (corresponding to the first baffle plate of the present invention) mainly includes the air reservoir section61ahaving a cylindrical shape, the extension cylinder61bhaving a cylindrical shape, and an upper cover61f.

The upper cover61fis provided on the plate30more than the air reservoir section61a. The difference between the upper cover61fand the upper cover60cis a central angle. In the B-B cross section, a central angle θ2of the upper cover61fis approximately 120 degrees.

Note that the central angle of the upper cover is not limited to 90 degrees or 120 degrees. Considering that the bubbles V1float in the +z direction due to buoyancy, the upper cover may be provided so as to intersect a line segment connecting the upper end portion of the filtration section10and the central axis ax.

Fourth Embodiment

In the first embodiment of the present invention, the baffle plate61B includes the air reservoir section61a, the extension cylinder61b, and the upper cover61e, but the form of the baffle plate is not limited to this. Below, description is given of a suction strainer4according to the fourth embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

FIG.8is a cross-sectional view schematically illustrating a suction strainer4.FIG.8partially omits hatching indicating a cross section.

The suction strainer4mainly includes the filtration section10, the attachment section20, the plate30, the cover40, the floats51and52, a baffle plate61D, and the attachment section70(partially not illustrated inFIG.8).

The baffle plate61D (corresponding to the first baffle plate of the present invention) is provided inside the filtration section10. The baffle plate61D has one end provided in the attachment section20. The baffle plate61D mainly includes the air reservoir section61ahaving a cylindrical shape and an extension cylinder61hhaving a cylindrical shape.

The extension cylinder61his provided on the plate30more than the air reservoir section61a. The extension cylinder61hhas a band-shaped region61iprovided with a large number of holes61j. The band-shaped region61iis provided in a band shape along the x direction below (−z side) the extension cylinder61h. The −x side of the band-shaped region61iis a cylindrical portion61g, and the +z side of the band-shaped region61iis an upper cover61k.

The upper cover61khas a cross-sectional shape that is an arc shape when taken along a plane orthogonal to the central axis ax. The upper cover61kis provided at a position intersecting a line segment connecting the upper end portion of the filtration section10and the central axis ax when taken along a plane orthogonal to the central axis ax.

Note that the position and shape of the band-shaped region61iare not limited to this. For example, the cylindrical portion61gis not essential. Although the central angle of the upper cover61kis 120 degrees, the central angle is not limited to this.

According to the present embodiment, the bubbles V1flowing into the space S3can be prevented from flowing out from the suction strainer4provided along the horizontal direction by retaining the bubbles V2in the space S3by the baffle plate61D. By providing the upper cover61k, bubbles flowing out of the suction strainer4can be further reduced.

In addition, according to the present embodiment, since the upper cover61kis a part of the extension cylinder61h, the assembly work is facilitated.

Fifth Embodiment

In the first embodiment of the present invention, the baffle plate61is provided inside the filtration section10, but the form of the baffle plate is not limited to this. In a fifth embodiment of the present invention, a baffle plate is provided outside the pleated filter12. Below, description will be given of a suction strainer5according to the fifth embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

FIG.9is schematic diagrams illustrating a suction strainer5, where (A) is a cross-sectional view and (B) is a perspective view.FIG.9partially omits hatching indicating a cross section. InFIG.9(B), a part of the filtration section10and the cover40are omitted for the sake of description.

The suction strainer5mainly includes the filtration section10, the attachment section20, the plate30, the cover40, the floats51and52, the baffle plate61C and a baffle plate62, and the attachment section70(partially not illustrated inFIG.9).

The baffle plate62(corresponding to the second baffle plate of the present invention) is provided below (−z side) the pleated filter12and below the central axis ax. In the present embodiment, the baffle plate62is provided outside the pleated filter12and inside the pleated filter11. The baffle plate62has the identical height to that of the filtration section10, and has one end provided on the attachment section20and the other end provided on the plate30.

FIG.10is a cross-sectional view schematically illustrating the suction strainer5taken along plane C-C inFIG.9(A). The baffle plate62is a lower cover having a cross-sectional shape that is an arc shape when taken along a plane (C-C plane) orthogonal to the central axis ax and provided at a position intersecting a line segment connecting the lower end portion of the filtration section10and the central axis ax. In the C-C plane, a central angle θ3of the baffle plate62is approximately 90 degrees.

The baffle plate62is provided along the pleated filter12adjacent to the pleated filter12. The baffle plate62is provided so as not to abut on the pleated filter12.

Next, the function of the suction strainer5configured as described above will be described with reference toFIG.9. After the suction strainer5is horizontally attached to the tank100, the hydraulic fluid is stored in the tank100.

Also regarding the suction strainer5, similarly to the suction strainer1, when suctioned by the hydraulic pump (not illustrated inFIG.9), the hydraulic fluid stored in the tank100is suctioned into the space S3from the outside of the cover40via the hole40aand the filtration section10, and flows out from the space S3to the suction pipe101via the hollow portion21cand the hollow portion22e. In addition, the floats51and52are pulled in the −z direction together with the hydraulic fluid, the float51closes the air vent hole22f, and the float52closes the hole of the cover40. Due to this, the hydraulic fluid does not flow into the space S3from a portion other than the hole40aand the filtration section10.

The bubbles V1contained in the hydraulic fluid are also suctioned into the space S3together with the hydraulic fluid. The hydraulic fluid flowing into the space S1from the hole40aand flowing into the space S2from below the filtration section10is blocked by the baffle plate62and flows along the baffle plate62(see arrow inFIG.9(B)). In particular, when the hydraulic fluid passes through the pleated filter11from below the filtration section10, the bubbles V1passing through the pleated filter11together with the hydraulic fluid are blocked by the lower side of the baffle plate62, and therefore the bubbles V1hardly flow into the space S3.

Even if the bubbles V1flow into the space S3, the bubbles V1flow in the +z direction and the −x direction along the flow of the hydraulic fluid, abut on the air reservoir section61a, and grow to become the large bubbles V2. In addition, the bubbles V1contained in the hydraulic fluid flowing into the space S2and the space S3from above or obliquely above the filtration section10also hit the upper cover61f, flow in the −x direction along the upper cover61f, abut on the air reservoir section61a, and grow to become the large bubbles V2. The bubbles V2are discharged into the space S1via the filtration section10when the hydraulic pump (not illustrated inFIG.9) stops.

According to the present embodiment, since the baffle plate62blocks the bubbles V1and the bubbles V1hardly flow into the space S3, it is possible to prevent inflow of the bubbles into the hollow portion (space S3) of the filtration section10. Even if the bubbles V1flow into the space S3, the baffle plate61C can retain the bubbles V2in the space S3. As a result, outflow of the bubbles from the suction strainer5can be prevented.

Note that in the present embodiment, the suction strainer5includes the baffle plate61C and the baffle plate62, but the baffle plate61C is not essential. Even when the suction strainer5includes only the baffle plate62, an effect of preventing outflow of bubbles from the suction strainer5can be achieved.

In the present embodiment, the baffle plate62is provided outside the pleated filter12and inside the pleated filter11, but the position where the baffle plate (lower cover) is provided is not limited to this. The baffle plate (lower cover) may be provided below (−z side) the pleated filter12and below the central axis ax. For example, as a baffle plate62A (corresponding to the second baffle plate of the present invention) inFIG.10, the baffle plate62A may be a lower cover provided outside the pleated filter11.

In addition, in the present embodiment, the central angle θ3of the baffle plate62is approximately 90 degrees, but the central angle of the baffle plate (lower cover) is not limited to this.FIGS.11and12are schematic diagrams illustrating suction strainers5A and5B having baffle plates62B and62C according to a modification, where (A) are perspective views, and (B) are cross-sectional views when taken along a plane orthogonal to the central axis ax. Note thatFIGS.11and12partially omit hatching indicating a cross section. InFIGS.11(A) and12(A), a part of the configuration is omitted.

Similarly to the baffle plate62, the baffle plates62B and62C (both correspond to the second baffle plate of the present invention) are lower covers having a cross-sectional shape that is an arc shape when taken along a plane orthogonal to the central axis ax and provided at positions intersecting a line segment connecting the lower end portion of the filtration section10and the central axis ax. The baffle plates62B and62C are different from the baffle plate62only in the central angle. As illustrated inFIG.11, a central angle θ4of the baffle plate62B is approximately 120 degrees, and as illustrated inFIG.12, a central angle θ5of the baffle plate62C is approximately 180 degrees.

That is, the baffle plate (lower cover) may be disposed at least below the central axis ax of the filtration section10, and a part of the baffle plate (lower cover) may be disposed at the same height as the central axis ax.

Sixth Embodiment

In the fifth embodiment of the present invention, the filtration section10includes the two pleated filters11and12, but the number of pleated filters included in the filtration section10is not limited to this.

The sixth embodiment of the present invention is a form in which the filtration section includes one pleated filter. Below, description will be given of a suction strainer6according to the sixth embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

FIG.13is a cross-sectional view schematically illustrating a suction strainer6. InFIG.13, hatching for indicating a cross section is omitted.

The suction strainer6mainly includes the filtration section10A, the attachment section20A, the plate30A, the float53, and the baffle plate62. The baffle plate62is provided along the pleated filter12adjacent to the pleated filter12of the filtration section10A. The baffle plate62is provided so as not to abut on the pleated filter12.

According to the present embodiment, the baffle plate62blocks the bubbles V1and the bubbles V1hardly flow into the space S3, whereby it is possible to prevent inflow of the bubbles into the hollow portion (space S3) of the filtration section10A and to prevent outflow of the bubbles from the suction strainer6provided along the horizontal direction.

Seventh Embodiment

In the first embodiment of the present invention, the bubbles V2accumulated on the air reservoir section61aare discharged via the filtration section10after the hydraulic pump is stopped, but the form of discharge of the bubbles V2is not limited to this. The seventh embodiment of the present invention is a form in which the bubbles V2are discharged via the air vent hole. A suction strainer7according to the seventh embodiment will be described below. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

FIG.14is a cross-sectional view schematically illustrating a suction strainer7.FIG.14partially omits hatching indicating a cross section.

The suction strainer7mainly includes the filtration section10, the attachment section20, the plate30, the cover40, the floats51and52, a baffle plate61E, and the attachment section70(partially not illustrated inFIG.14).

The baffle plate61E (corresponding to the first baffle plate of the present invention) is provided inside the filtration section10. Similarly to the baffle plate61, the baffle plate61E includes an air reservoir section61lhaving a cylindrical shape and an extension cylinder61mhaving a cylindrical shape provided in the air reservoir section61l.

The baffle plate61E is inserted into the hollow portion22eof the cylindrical portion22a, and has one end provided in the cylindrical portion21a. Therefore, the space above the air reservoir section61lcommunicates with the air vent hole22f.

Also in the suction strainer7, similarly to the suction strainer1, the bubbles V1suctioned into the filtration section10together with the hydraulic fluid flow in the +z direction and the −x direction along the flow of the hydraulic fluid, and abut on the baffle plate61E. Then, the bubbles V1accumulate in a space above the baffle plate61E (air reservoir section61l), and grow into the large bubbles V2. When the bubbles V2flow into the air vent hole22fand push up the float52in the +z direction, the holes of the cover40are opened, and the bubbles V2are released from the space S1to the outside of the suction strainer1.

According to the present embodiment, by blocking the bubbles V2by the baffle plate61E, it is possible to prevent outflow of the bubbles from the suction strainer7provided along the horizontal direction. By allowing the space above the air reservoir section61land the air vent hole22fto communicate with each other, the bubbles V2can be discharged into the space S1even during operation (during operation of the hydraulic pump103).

The embodiments of the invention are described above in detail with reference to the drawings. However, specific configurations are not limited to the embodiments and also include changes in design or the like without departing from the gist of the invention. For example, in the examples described above, detailed description is made to facilitate understanding of the present invention, and the examples are not necessarily limited to examples including all the configurations described above. In addition, the configuration of an embodiment can be replaced partially with the configurations of other embodiments. In addition, addition, deletion, replacement or the like of other configurations can be made on the configurations of the embodiments.

Additionally, in the present invention, “substantially” is a concept not only including the case of being strictly the same, but also including an error and deformation to the extent that a loss of identity does not occur. For example, the term “substantially orthogonal” is not limited to the case of being strictly orthogonal, but includes a concept that includes deviations of several degrees, for example. Further, simple expressions such as orthogonal, parallel, and identical are not to be understood as merely being strictly, for example, orthogonal, parallel, and identical, and include being, for example, substantially parallel, substantially orthogonal, and substantially identical.

Additionally, in the present invention, “vicinity” means to include a region in a certain range (the range can be determined arbitrarily) near a reference position. For example, the term “a vicinity of an end” refers to a range of regions in the vicinity of the end, and is a concept indicating that the end may or need not be included.

REFERENCE SIGNS LIST