阅读说明：本技术 过滤器装置 (Filter device ) 是由 北岛信行 冈本美信 山口光广 于 2020-04-22 设计创作，主要内容包括：本发明能够在过滤器元件的更换时避免液体向外部滴落。将过滤器元件的内部的空间与过滤器壳体的外部的空间连通的流出部具有分开设置的上表面以及底面。背压阀具有大致板状的阀芯、以及设置于底面与阀芯之间的弹性构件。阀芯能够在阀芯同上表面抵接的关闭位置和阀芯同上表面不抵接的打开位置之间移动。在阀芯,在与上表面抵接的面设置有凹部,在流出部的侧面或上表面形成有流出口,在关闭位置,过滤器元件的内部的空间与过滤器壳体的外部的空间由在凹部与上表面之间形成的空间连通。(The invention can avoid liquid dropping to the outside when the filter element is replaced. The outflow portion that communicates the space inside the filter element with the space outside the filter case has an upper surface and a bottom surface that are provided separately. The back pressure valve has a substantially plate-shaped valve body, and an elastic member provided between the bottom surface and the valve body. The valve element is movable between a closed position in which the valve element abuts the upper surface and an open position in which the valve element does not abut the upper surface. In the valve body, a recess is provided on a surface abutting on the upper surface, an outlet is formed on a side surface or the upper surface of the outlet, and in the closed position, a space inside the filter element and a space outside the filter case are communicated with each other by a space formed between the recess and the upper surface.)

1. A filter device provided in a tank for storing a liquid, the filter device being characterized in that,

the filter device is provided with:

a filter housing having a substantially bottomed cylindrical shape, which is attached to the tank and has an open upper end;

a filter element provided inside the filter housing and having a first filter material having a substantially cylindrical shape;

a cover body which is provided to the filter case and the filter element so as to cover an upper end of the filter case, and which has an air discharge hole that communicates a space inside the filter element with a space outside the filter case;

an inflow unit that allows the liquid to flow into a space inside the filter housing and outside the filter element;

an outflow portion that communicates a space inside the filter element with a space outside the filter housing; and

a back pressure valve provided in the outflow portion,

the outflow portion has: an upper surface and a bottom surface which are separately provided; and a first cylindrical portion provided so as to protrude upward from the upper surface and attached to a through hole formed in the filter case,

the upper surface has a first hole which communicates with the hollow portion of the first cylindrical portion and into which the liquid flows toward the outflow portion,

an outlet through which the liquid flows out of the outflow portion is provided on a side surface or the upper surface of the outflow portion,

the back pressure valve has a substantially plate-shaped valve body and a first elastic member provided between the bottom surface and the valve body,

the valve element is movable between a closed position in which the valve element abuts the upper surface and the valve element covers the first aperture, and an open position in which the valve element does not abut the upper surface,

a recess is provided on a surface of the valve body abutting against the upper surface,

in the closed position, a space inside the filter element and a space outside the filter housing are communicated by a space formed between the recess and the upper surface.

2. The filter device of claim 1,

the filter housing is disposed inside the canister,

the cover body is arranged on the upper side of the tank,

both ends of the air discharge hole are opened on the lower surface of the cover, and the air discharge hole communicates the space inside the filter element with the space outside the filter housing and inside the tank.

3. A filter device according to claim 1 or 2,

the filter housing is narrowed at a portion adjacent to the opening at the upper end.

4. A filter device according to any one of claims 1 to 3,

the filter device has a second filter material of a substantially cylindrical shape,

the upper side of the second filter material is covered by the bottom surface,

a mounting member is arranged on the lower side of the second filter material,

the second filter material is provided to the tank by the mounting member.

5. A filter device according to any one of claims 1 to 3,

the filter device has a second filter material of a substantially cylindrical shape,

a plate-like member that covers the upper side of the second filter material is provided on the upper side of the second filter material,

the bottom surface is detachably provided to the plate-like member,

a second elastic member is provided between the plate-like member and the bottom surface,

a mounting member is arranged on the lower side of the second filter material,

the second filter material is provided to the tank by the mounting member.

6. The filter device of claim 5,

the bottom surface has a second cylindrical portion of a substantially cylindrical shape projecting downward,

the plate-like member has a third cylindrical portion having a substantially cylindrical shape and a diameter larger than that of the second cylindrical portion, and a claw portion projecting radially inward of the third cylindrical portion,

the claw part has elasticity, and the claw part has elasticity,

when the second cylindrical portion is inserted inside the third cylindrical portion, the claw portion is elastically deformed to press the second cylindrical portion.

7. The filter device of claim 6,

the second cylindrical portion has a substantially cylindrical shape,

a groove having a first groove extending substantially in a horizontal direction, and a second groove and a third groove provided at both ends of the first groove, respectively, is formed on an outer peripheral surface of the second cylindrical portion,

the second groove and the third groove extend downward in the vertical direction from the first groove,

the lower end of the second groove reaches the lower end of the second cylindrical portion,

the lower end of the third groove does not reach the lower end of the second cylindrical portion.

8. The filter device according to any one of claims 1 to 7,

the filter element has an upper plate provided at an end of an upper side of the first filter material,

a protrusion protruding downward is formed on the back surface of the cover,

a second hole into which the protrusion is inserted is formed in the upper plate.

9. The filter device according to any one of claims 1 to 7,

the filter element has an upper plate provided at an end of an upper side of the first filter material,

the upper plate has a substantially cylindrical fourth cylindrical portion adjacent to the inside of the first filter material,

the cover body has a protruding part with the front end inserted into the fourth cylindrical part,

the air discharge hole has an open end formed at the protrusion,

the opening end has a substantially conical shape or a substantially truncated conical shape with an inner diameter decreasing toward the upper side.

10. The filter device according to any one of claims 1 to 9,

the upper surface has a side surface portion in the shape of a truncated cone side surface.

11. The filter device according to any one of claims 1 to 10,

the outlet is formed in the upper surface at a position overlapping the recess in a plan view.

12. The filter device according to any one of claims 1 to 10,

the side surface of the outflow portion is open between the bottom surface and the upper surface, and the opening is the outflow port.

13. The filter device of claim 12,

an inclined surface is provided on a surface of the bottom surface facing the upper surface.

14. The filter device of claim 13,

the inclined surface is locally missing.

Technical Field

The present invention relates to a filter device.

Background

Patent document 1 discloses a liquid filter including a check valve that blocks a flow path of a liquid when an internal combustion engine is stopped.

Documents of the prior art

Patent document

Patent document 1: japanese Kokai publication No. 2009-536088

Disclosure of Invention

Problems to be solved by the invention

In the invention described in patent document 1, the flow path of the liquid is completely blocked at the time of stopping the internal combustion engine. Therefore, when the internal combustion engine is stopped and the filter element is replaced, the liquid sealed in the filter case is taken out together with the filter element, and the liquid drops to the outside of the liquid filter.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a filter device capable of preventing liquid from dripping to the outside when a filter element is replaced.

Means for solving the problems

In order to solve the above problem, a filter device according to the present invention is a filter device provided in a tank for storing a liquid, for example, the filter device including: a filter housing having a substantially bottomed cylindrical shape, which is attached to the tank and has an open upper end; a filter element provided inside the filter housing and having a substantially cylindrical filter material; a cover body which is provided to the filter case and the filter element so as to cover an upper end of the filter case, and which has an air discharge hole that communicates a space inside the filter element with a space outside the filter case; an inflow unit that allows the liquid to flow into a space inside the filter housing and outside the filter element; an outflow portion that communicates a space inside the filter element with a space outside the filter housing; and a back pressure valve provided in the outflow portion, the outflow portion including: an upper surface and a bottom surface which are separately provided; and a first cylindrical portion provided so as to protrude upward from the upper surface and attached to a through hole formed in the filter case, wherein the upper surface has a first hole that communicates with a hollow portion of the first cylindrical portion and through which the liquid flows into the outflow portion, an outflow port through which the liquid flows out from the outflow portion is provided in a side surface or the upper surface of the outflow portion, the back pressure valve has a substantially plate-shaped valve element, and a first elastic member provided between the bottom surface and the valve element, the valve element is movable between a closed position in which the valve element abuts against the upper surface and the valve element covers the first hole and an open position in which the valve element does not abut against the upper surface, a recess is provided in a surface of the valve element abutting against the upper surface, and in the closed position, a space inside the filter element and a space outside the filter case are formed by a space inside the recess Communicating with the space formed between said upper surfaces.

According to the filter device of the present invention, the outflow portion that communicates the space inside the filter element with the space outside the filter housing has the upper surface and the bottom surface that are provided separately. The back pressure valve has a substantially plate-shaped valve body, and an elastic member provided between the bottom surface and the valve body. The valve element is movable between a closed position in which the valve element abuts against the upper surface and the valve element covers the first hole of the upper surface, and an open position in which the valve element does not abut against the upper surface. In the valve body, a recess is provided on a surface abutting against the upper surface, and in the closed position, a space inside the filter element and a space outside the filter housing are communicated with each other by a space formed between the recess and the upper surface. Therefore, when the engine is stopped, the liquid can be made to flow out from the filter case without detaching the cover from the filter case, and the oil in the filter element can be removed. This can prevent the hydraulic oil from dropping (oil dripping) to the outside of the filter device at the time of replacement. Further, since the air in the filter case is discharged through the air discharge hole, it is possible to prevent the occurrence of corrosion or the like.

The filter case may be provided inside the tank, the cover may be provided on an upper side of the tank, both ends of the air discharge hole may be open on a lower surface of the cover, and the air discharge hole may communicate a space inside the filter element with a space outside the filter case and inside the tank. Thus, even if the working oil passes through the air discharge hole, the working oil can be returned to the tank.

The filter housing is narrowed at a portion adjacent to the opening at the upper end. Thus, when the liquid passes through the air vent hole, the liquid flows into the tank along the filter case, and therefore, it is possible to prevent air bubbles from being generated in the liquid stored in the tank.

The filter device includes a substantially cylindrical second filter member, an upper side of the second filter member being covered with the bottom surface, and an attachment member provided on a lower side of the second filter member, the second filter member being provided to the tank via the attachment member. This can shorten the overall length of the filter device in which the reflux filter and the suction strainer are integrated.

The filter device includes a substantially cylindrical second filter member, a plate-shaped member provided on an upper side of the second filter member to cover an upper side of the second filter member, a bottom surface detachably provided on the plate-shaped member, a second elastic member provided between the plate-shaped member and the bottom surface, and an attachment member provided on a lower side of the second filter member, the second filter member being provided on the tank via the attachment member. This enables the entire length of the filter device to be adjusted. In addition, the outflow portion and the second filter material can be detachable.

The bottom surface has a second cylindrical portion of a substantially cylindrical shape protruding downward, the plate-like member has a third cylindrical portion of a substantially cylindrical shape having a larger diameter than the second cylindrical portion, and a claw portion protruding radially inward of the third cylindrical portion, the claw portion has elasticity, and when the second cylindrical portion is inserted into the third cylindrical portion, the claw portion is elastically deformed to press the second cylindrical portion. This makes it possible to attach and detach the outflow portion and the plate-shaped member, and to reliably attach the outflow portion to the plate-shaped member.

The second cylindrical portion has a substantially cylindrical shape, and a groove having a first groove extending substantially in a horizontal direction and a second groove and a third groove provided at both ends of the first groove is formed in an outer peripheral surface of the second cylindrical portion, the second groove and the third groove extending downward in a vertical direction from the first groove, a lower end of the second groove reaching a lower end of the second cylindrical portion, and a lower end of the third groove not reaching the lower end of the second cylindrical portion. Thus, the claw is moved along the groove by pressing and rotating the outflow portion, and the outflow portion can be reliably attached to the plate-like member. Further, since the lower end of the third groove does not reach the lower end of the cylindrical portion, the outflow portion is not pulled out from the plate-like member when the entire length of the filter device is adjusted by the elastic member.

The filter element has an upper plate provided at an upper end of the first filter material, a protrusion protruding downward is formed on a rear surface of the cover, and a second hole into which the protrusion is inserted is formed in the upper plate. This can prevent the use of a filter element other than a normal product.

The filter element has an upper plate provided at an upper end of the first filter material, the upper plate has a substantially cylindrical fourth cylindrical portion adjacent to an inner side of the first filter material, the cover has a protruding portion into which a leading end is inserted, and the air discharge hole has an open end formed in the protruding portion, the open end having a substantially conical shape or a substantially truncated conical shape whose inner diameter becomes smaller as going upward. This makes it easy for air bubbles generated inside the filter element to collect in the air outlet hole. Further, the air bubbles collected at the open end are collected in a narrow area as they go upward, and therefore the air bubbles are easily discharged from the air discharge hole.

The upper surface has a side surface portion in the shape of a truncated cone side surface. This enables the hydraulic oil to flow obliquely downward along the side surface portion. As a result, the contact of the hydraulic oil with the side surface of the tank can be avoided, and a problem (e.g., foaming of the hydraulic oil) caused by the contact of the hydraulic oil with the side surface of the tank can be prevented.

The outlet is formed in the upper surface at a position overlapping the recess in a plan view. Thus, the working oil flowing through the space formed between the recess and the upper surface is easily discharged to the space outside the filter case.

The side surface of the outflow portion is open between the bottom surface and the upper surface, and the opening is the outflow port. This facilitates the flow of the working oil obliquely downward along the side surface portion.

An inclined surface is provided on a surface of the bottom surface facing the upper surface. This enables the hydraulic oil to flow obliquely downward along the inclined surface.

The inclined surface is locally missing. This can increase the volume between the bottom surface and the upper surface. Therefore, even when the engine is operated and the working oil flows in a large amount, the flow of the working oil is not hindered.

Effects of the invention

According to the present invention, it is possible to prevent liquid from dripping to the outside when the filter element is replaced.

Drawings

Fig. 1 is a cross-sectional view schematically showing a filter device 1 according to an embodiment of the present invention.

Fig. 2 is an enlarged view of the vicinity of the upper end of the filter device 1.

Fig. 3 is a cut-away perspective view of the filter device 1.

Fig. 4 is a perspective view of the outflow portion 40 and the suction strainer 50.

Fig. 5 is a sectional perspective view of the outflow portion 40 and the suction strainer 50.

Fig. 6 is a sectional view of the outflow portion 40 and the suction strainer 50.

Fig. 7 is a sectional perspective view of the outflow portion 40 and the suction strainer 50.

Fig. 8 is a sectional view of the outflow portion 40 and the suction strainer 50.

Fig. 9 is a sectional view of the outflow portion 40 and the back pressure valve 70.

Fig. 10 is a cross-sectional view schematically showing a filter device 2 according to an embodiment of the present invention.

Fig. 11 is a perspective view of the filter device 2 with the cover body 32A and the cover 33 removed.

Fig. 12 is a perspective view of the cover main body 32A as viewed from below.

Fig. 13 is a schematic cross-sectional view showing the outflow portion 40A, the suction strainer 50, and the back pressure valve 70A.

Fig. 14 is a schematic cross-sectional view showing the outflow portion 40A, the suction strainer 50, and the back pressure valve 70A.

Fig. 15 is a schematic cross-sectional view showing the outflow portion 40A, the suction strainer 50, and the back pressure valve 70A.

Fig. 16 is a side view schematically showing the outflow portion 40A.

Fig. 17 is a perspective view showing an outline of the outflow portion 40A, and is a view seen through a main part.

Fig. 18 is a diagram showing the flow of the hydraulic oil at the idling time of the engine.

Fig. 19 is a diagram showing the flow of the hydraulic oil when the engine is operating.

Fig. 20 is a sectional view showing an outline of the filter device 4.

Fig. 21 is a sectional view showing an outline of the filter device 4.

Fig. 22 is a perspective view showing the vicinity of the lid 30B enlarged

Fig. 23 is a schematic cross-sectional view showing the outflow portion 40B, the suction strainer 50A, and the back pressure valve 70A.

Fig. 24 is a schematic cross-sectional view showing the outflow portion 40B, the suction strainer 50A, and the back pressure valve 70A.

Fig. 25 is a view showing an outline of the suction strainer 50A, where (a) is a plan view and (B) is a sectional view.

Fig. 26 is a view showing an outline of the bottom surface 44B, where (a) is a cross-sectional view and (B) is a perspective view.

Fig. 27 is a view showing an outline of the outflow portion 40C in the modification, (a) is a side view, and (B) is a cross-sectional view.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, the working oil is described as an example of the liquid to be filtered, but the liquid to be filtered is not limited to the working oil. In the following embodiments, a return filter is described as an example, but the filter device of the present invention is not limited to the return filter.

< first embodiment >

Fig. 1 is a cross-sectional view schematically showing a filter device 1 according to an embodiment of the present invention. In fig. 1, a part of hatching showing a cross section is omitted.

The filter device 1 is a device in which a reflux filter and a suction strainer are integrated. The filter device 1 is provided to the tank 100. The tank 100 is a tank for storing working oil, and is, for example, box-shaped. The tank 100 is provided in a working machine (e.g., a hydraulic device) not shown, and is provided in a hydraulic circuit of hydraulic oil supplied to the hydraulic device. However, the tank 100 is not limited to being provided in the hydraulic circuit.

An opening 101a to which the filter device 1 is attached is formed in the upper surface 101 of the tank 100. The filter device 1 is attached to the upper surface 101 via an attachment plate 105 (see fig. 3). However, the mounting plate 105 is not necessary.

A substantially cylindrical inflow pipe 106 for allowing the hydraulic oil to flow into the filter device 1 is fitted to a side surface (not shown) of the tank 100. The inflow pipe 106 guides the working oil from the outside of the tank 100 to the filter device 1. The working oil introduced to the filter device 1 is filtered by the filter device 1 and stored in the tank 100.

An outlet port 102a for discharging the hydraulic oil in the tank 100 to a hydraulic pump (not shown) or the like is formed in the bottom surface 102 of the tank 100. A suction strainer 50 is provided inside the tank 100, and the hydraulic oil that has passed through the suction strainer 50 flows out from the outflow port 102a to the outside of the tank 100. The outlet port 102a may be provided on a side surface of the tank 100.

Next, the filter device 1 will be explained. The filter device 1 mainly includes a filter case 10, a filter element 20, a lid 30, an outflow portion 40, a suction strainer 50, and a back pressure valve 70.

The filter case 10 is formed of a material having high corrosion resistance (for example, metal such as stainless steel). The filter case 10 is provided inside the tank 100 so as to protrude downward (to the (-z side)) from the upper surface 101 of the tank 100.

The filter case 10 has a substantially cylindrical shape with a bottom, and an upper end surface is open. The interior of the filter case 10 is a cavity, and a filter element 20 and the like are provided therein. The substantially cylindrical shape is a concept including a substantially cylindrical shape, a substantially elliptical cylindrical shape, and the like, but in the present embodiment, a substantially cylindrical shape is illustrated.

The filter housing 10 mainly includes a first housing 11 having a substantially cylindrical shape, a second housing 12 having a substantially cylindrical shape, a mounting portion 13, a third housing 14, and an inner housing 15. A second housing 12 and a mounting portion 13 are provided on the upper side (+ z side) of the first housing 11.

Fig. 2 is an enlarged view of the vicinity of the upper end of the filter device 1. In fig. 2, a part of hatching showing a cross section is omitted. The attachment portion 13 is a member for attaching the filter housing 10 to the upper surface 101 of the tank 100, and includes a plate-shaped portion 13a attached to the lid 30 and a cylindrical portion 13b provided below the plate-shaped portion 13 a. The cylindrical portion 13b is provided with a small diameter portion 12a of the second housing 12. The second housing 12 and the mounting portion 13 may be one member.

The portion of the filter case 10 adjacent to the upper end opening is an upper end portion 10a, and here, this portion corresponds to the small diameter portion 12a and the cylindrical portion 13b (see fig. 2). The diameter of the upper end portion 10a is smaller than the diameters of portions other than the upper end portion 10a, for example, the first casing 11 and the third casing 14. That is, the upper end portion 10a of the filter housing 10 is narrowed.

The explanation returns to fig. 1. A third housing 14 and an inner housing 15 are provided below the first housing 11. The third casing 14 has a substantially cylindrical shape with a bottom, and an inner casing 15 is provided inside the third casing 14.

A through hole 14c is formed in the bottom surface 14a of the third housing 14. The through hole 14c is provided with an outflow portion 40. The outflow portion 40 communicates the space inside the filter element 20 with the space outside the filter housing 10. The outflow portion 40 will be described in detail later. A hole 14b into which the inflow pipe 106 is inserted is provided in a side surface of the third housing 14. The hole 14b may be provided on a side surface of the third casing 14 other than the side surface, and the through hole 14c may be provided on a bottom surface 14a other than the side surface.

The inner housing 15 is a member that divides the space in the third housing 14 into two parts, and has an outer cylindrical portion 15a and an inner cylindrical portion 15 b. The cylindrical portion 15a is provided with a hole 15c into which the inflow tube 106 is inserted. The holes 15c and 14b are inflow portions for allowing the liquid to flow into the space (space S1) inside the filter case 10 and outside the filter element 20. The cylindrical portion 15b is provided with a valve 61.

Normally, the valve 61 is closed, but when the filter material 21 is clogged and the pressure in the filter case 10 becomes high, the valve 61 is opened, and the working oil flows from the space S1 to the space (space S2) inside the filter element 20, thereby preventing the filter device 1 from being damaged. The valve 61 is already known, and therefore, the description is omitted.

The filter element 20 is a member having a substantially cylindrical shape with a bottom, and is provided inside the filter case 10. The filter element 20 mainly includes a filter material 21, an outer cylinder 22, an inner cylinder 23, and plates 24 and 25. The outer cylinder 22, the inner cylinder 23, and the plates 24 and 25 are integrated with the filter 21.

The filter 21 is a substantially cylindrical member having openings at both ends. The filter material 21 is formed as follows: a filter paper using synthetic resin, paper, or the like is folded into pleats, and both ends of the folded filter paper are connected to each other to form a cylindrical shape. An outer cylinder 22 is provided outside the filter 21, and the outer cylinder 22 has a hole for supplying the working oil formed substantially over the entire area. Further, an inner tube 23 is provided inside the filter member 21, and the inner tube 23 has a hole through which the working oil passes substantially over the entire region. It should be noted that the inner cylinder 23 is not essential.

A plate 24 is provided at the upper end of the filter 21, the outer cylinder 22, and the inner cylinder 23. The plate 24 abuts the lid 30.

A plate 25 is provided at the lower end of the filter 21, the outer cylinder 22, and the inner cylinder 23. A portion near the upper end of the cylindrical portion 15b is inserted into the hollow portion of the plate 25. Thereby, the filter element 20 is provided to the filter housing 10.

The lid 30 is provided outside the can 100 (above the upper surface 101 in the present embodiment). The lid 30 is provided to the filter case 10 (here, the attachment portion 13) and the filter element 20 (here, the plate 24) so as to cover an opening portion of an upper end surface of the filter case 10.

Fig. 3 is a cut-away perspective view of the filter device 1. In fig. 3, a part of hatching showing a cross section is omitted. The lid 30 mainly includes a mounting portion 31, a lid main body 32, and a cover 33.

The attachment portion 31 has a substantially cylindrical shape, and is fixed to the filter case 10 (the attachment portion 13 here) and the tank 100 (not shown in fig. 2 and 3) by screws 65. As shown in fig. 2, the mounting portion 31 has a protruding portion 31a protruding outward. A hole 31b is formed in the projection 31a, and a differential pressure sensor 62 is provided in the hole 31 b. The protruding portion 31a is formed with a hole 31c that communicates the pocket 31b with the space S1.

As shown in fig. 3, the cover body 32 is a substantially thick plate-shaped member, and is provided so as to cover the hollow portion of the mounting portion 31 from above the mounting portion 31. The cover main body 32 is fixed to the mounting portion 31 by screws 66. Sealing members 81 and 82 for preventing leakage of the working oil are provided between the mounting portion 31 and the cover main body 32.

The lid main body 32 mainly includes a flange portion 32a, a substantially cylindrical first cylindrical portion 32b disposed inside the flange portion 32a, a substantially bottomed cylindrical second cylindrical portion 32c disposed inside the first cylindrical portion 32b, and a substantially plate-like plate portion 32d connecting the first cylindrical portion 32b and the second cylindrical portion 32 c. The flange portion 32a abuts the upper surface of the mounting portion 31, and the first cylindrical portion 32b abuts the inner peripheral surface of the mounting portion 31. The lower surface of the plate-like portion 32d abuts against the plate 24, and the second cylindrical portion 32c is inserted into the inner cylinder 23.

As shown in fig. 2, the cover main body 32 is provided with a plurality of holes 32e serving as flow paths for air and hydraulic oil. One end of one hole 32e of the plurality of holes 32e is opened at the cavity 31b, and the hole 32e communicates the cavity 31b with the space S2. Since the hole 31c communicates the hole 31b with the space S1, the differential pressure sensor 62 is provided in the mounting portion 31, whereby the difference between the pressure inside the filter case 10 and the pressure outside the case can be detected. The other hole 32e communicates with a hole 31e (see fig. 3) formed in the mounting portion 31.

As shown in fig. 2 and 3, the holes 31e and 32e are air discharge holes 39, and both ends are open on the lower surface of the lid body 30. The hole 31e and the hole 32e communicate the space S2 and the space S3 (see fig. 1) via the hole 13c formed in the mounting portion 13 and the notch 105a formed in the mounting plate 105. Here, the space S3 is a space outside the filter case 10 and inside the tank 100. The mounting portion 13 and the mounting plate 105 are not essential, and in the absence of these components, the hole 31e and the hole 32e directly communicate the space S2 with the space S3.

The cover body 32 is provided with a cover 33. The cover 33 is a substantially plate-shaped member, and is provided above the cover main body 32. The cover main body 32 and the cover 33 may be one member.

The explanation returns to fig. 1. The outflow portion 40 is provided below the filter case 10 so as to cover the through hole 14c provided in the bottom surface 14a of the third case 14. The outflow portion 40 communicates the space S2 with the space S3. A suction strainer 50 is provided below the outflow portion 40.

Fig. 4 is a perspective view of the outflow portion 40 and the suction strainer 50. Fig. 5 and 7 are sectional perspective views of the outflow portion 40 and the suction strainer 50. Fig. 6 and 8 are sectional views of the outflow portion 40 and the suction strainer 50. In FIGS. 5 to 8, hatching showing cross sections is partially omitted.

The outflow portion 40 mainly includes cylindrical portions 41 and 42, a coupling portion 43, and a substantially plate-shaped bottom surface 44. The cylindrical portions 41 and 42 are substantially cylindrical, and the diameter of the cylindrical portion 42 is larger than that of the cylindrical portion 41.

The coupling portion 43 has a substantially plate-shaped upper surface 43a, and a cylindrical portion 43b provided on the upper surface 43a so as to protrude upward. The outer peripheral surface of the upper surface 43a is connected to the cylindrical portion 42.

The cylindrical portion 41 is provided on the coupling portion 43 so as to protrude upward from the upper surface 43 a. The cylindrical portion 43b is fitted into the cylindrical portion 41. By inserting the cylindrical portion 41 and the cylindrical portion 43b into the through hole 14c of the third housing 14, the cylindrical portion 41 and the cylindrical portion 43b, that is, the outflow portion 40 are attached to the filter housing 10.

The upper surface 43a is provided with an outlet port 43c through which the working oil flows out of the outflow portion 40. The outlet 43c is disposed at a position overlapping the recess 71b (described later in detail) in a plan view (when viewed from the z direction).

The cylindrical portion 43b is provided with a hole 43e defined by a plurality of ribs 43d extending in the radial direction. For this purpose, a hole 43h communicating with the hole 43e is provided in the upper surface 43 a. The hollow portions of the holes 43e and 43h are holes through which the hydraulic oil flowing out of the space S2 flows into the outflow portion 40. A rod-shaped portion 43f that connects the plurality of ribs 43d is provided substantially at the center of the cylindrical portion 43 b.

The upper surface 43a is provided separately from the bottom surface 44. The bottom surface 44 is provided with a rib 44a projecting upward, and the upper surface 43a and the bottom surface 44 are integrated by screwing a screw 67 into screw holes formed in the upper surface 43a and the rib 44 a.

A back pressure valve 70 is provided in a space between the upper surface 43a and the bottom surface 44. The back pressure valve 70 mainly includes a substantially plate-shaped valve body 71, an elastic member 72 provided between the valve body 71 and the bottom surface 44, and a rod member 73 not disposed on the rod portion 43f and the bottom surface 44.

Fig. 5 and 6 show the case where the valve body 71 is located at the closed position where the valve body 71 abuts on the upper surface 43 a. Fig. 7 and 8 show a case where the valve body 71 is located at an open position where the valve body 71 does not abut on the upper surface 43 a.

The rod member 73 is inserted into the recess 44b provided in the bottom surface 44 and into the hole 43g formed in the rod portion 43 f. Thereby, the rod-like member 73 extends in the vertical direction (z direction).

A hole 71a into which the rod member 73 is inserted is formed in the center of the valve body 71. The spool 71 is movable in the z direction between a closed position and an open position along the rod member 73.

The elastic member 72 lifts the valve body 71 upward (+ z direction). The elastic member 72 lifts the valve body 71 until the valve body 71 abuts on the upper surface 43 a. That is, the upper surface 43a functions as a valve seat of the back pressure valve 70. In the closed position where the spool 71 abuts the upper surface 43a, the spool 71 covers the hole 43 h. As the pressure inside the filter case 10 increases, the valve body 71 moves downward against the urging force of the elastic member 72.

The valve body 71 has a recess 71b on a surface abutting against the upper surface 43 a. Fig. 9 is a cross-sectional view showing the outflow portion 40 and the back pressure valve 70 when the valve body 71 is in the closed position (the back pressure valve 70 is in the closed state). Since the recess 71b is formed in the valve body 71, a small space is formed between the recess 71b and the upper surface 43a even if the valve body 71 abuts on the upper surface 43 a. As a result, the space (i.e., the space S2) inside the cylindrical portion 43b communicates with the space S3 due to the space formed between the recess 71b and the upper surface 43a, and the hydraulic oil can pass between the recess 71b and the upper surface 43a even when the back pressure valve 70 is in the closed state. Further, since the outflow port 43c is disposed at a position overlapping the recess 71b in a plan view, the working oil flowing through the space formed between the recess 71b and the upper surface easily flows out into the space S3.

The explanation returns to fig. 4 to 8. The suction strainer 50 has a filter material 51 having a substantially cylindrical shape. The filter member 51 is a filter portion through which the working oil can pass. The upper opening of the filter member 51 is covered with the bottom surface 44. A mounting member 52 is provided below the filter material 51. The mounting member 52 is provided with the filter material 51 on the bottom surface 102 so that the suction strainer 50 covers the outflow port 102 a. A seal member 83 is provided between the mounting member 52 and the outflow port 102a so that the working oil does not leak.

Next, the function of the filter device 1 configured as described above will be explained. The two-dot chain line arrows in fig. 1, 3, 7, and 9 indicate the flow of the working oil.

When the operation of the engine of the working machine is stopped, the filter case 10 does not contain the working oil. Therefore, as shown in fig. 1, the back pressure valve 70 is in a closed state, and the space S2 and the space S3 do not communicate with each other through the outflow portion 40.

When the driving of the working machine is started, as shown in fig. 1, the hydraulic oil starts to flow in the hydraulic circuit, and along with this, the hydraulic oil gradually flows into the space S1. Since the filter case 10 (spaces S1, S2) is filled with the initial air, the initial air is discharged into the space S3 through the air discharge holes 39 (holes 31e (not shown in fig. 1) and holes 32e) as the oil level position in the filter case 10 rises (moves in the + z direction).

The hydraulic oil flowing into the space S1 flows from the outside toward the inside of the filter member 21, and dust and the like in the hydraulic oil are removed by the filter member 21. The filtered working oil flows out to the space S2.

At the idling speed of the engine, the flow rate of the working oil is small, and is approximately 40L (liters)/min. In this case, the hydraulic oil gradually flows into the filter case 10 from an inflow portion not shown, but the back pressure valve 70 is in a closed state as shown in fig. 1 because the flow rate of the hydraulic oil is small and the pressure inside the filter case 10 has not yet become sufficiently high. As a result, the oil level rises to the position of the oil level L indicated by the broken line. Since the back pressure valve 70 is in the closed state during idling, the filtered hydraulic oil flows out to the space S3 through the space between the recess 71b and the upper surface 43 a.

When the engine is running, the flow rate of the working oil increases, and the flow rate increases to approximately 1000L (liters)/min. In this case, the working oil flows into the filter case 10 from an inflow portion not shown, the inside of the filter case 10 is filled with the working oil, and the pressure inside the filter case 10 becomes sufficiently high. Therefore, as shown in fig. 7, the working oil presses down the valve body 71 against the urging force of the elastic member 72, and the back pressure valve 70 is opened. As a result, the filtered working oil passes through the outflow portion 40 and flows out to the space S3.

When the interior of the filter case 10 is filled with the hydraulic oil during the operation of the engine, a part of the hydraulic oil flows out to the space S3 through the air outlet hole 39 (the hole 31e and the hole 32 e). Since the upper end portion 10a of the filter case 10 is narrowed, the hydraulic oil that has passed through the air discharge hole 39 does not directly fall toward the hydraulic oil stored in the tank 100, but is stored in the tank 100 along the cylindrical portion 13b and the small diameter portion 12a (see the two-dot chain line arrow in fig. 3). This can prevent the generation of bubbles in the liquid stored in the tank. However, in practice, air is likely to accumulate in the upper portion of the filter case 10, and therefore the possibility of the hydraulic oil flowing out of the air discharge hole 39 is low.

The hydraulic oil that has flowed out into the space S3 flows out of the tank 100 from the outflow port 102a through the suction strainer 50.

When the engine is stopped, air flows from the space S3 into the spaces S1 and S2 through the air outlet hole 39. As shown in fig. 9, the filtered hydraulic oil passes between the recess 71b and the upper surface 43a and flows out into the space S3. Thus, the oil level gradually lowers even if the cover body 32 is not detached from the attachment portion 31 (synonymous with the filter case 10). Therefore, when a certain time (for example, about five minutes) has elapsed after the work machine is stopped, the oil level is lowered below the plate 25 without detaching the cover body 32 from the attachment portion 31 (filter housing 10).

When the cover body 32 of the cover body 30 is detached from the attachment portion 31, the filter element 20 is pulled out from the open end of the upper portion of the filter case 10. Since the oil level is lower than the plate 25 after a certain time has elapsed after the work machine is stopped, the filter element 20 is not immersed in the working oil, and the used filter element 20 in the state where the oil is removed can be pulled out. As a result, the hydraulic oil can be prevented from dripping to the outside of the filter device 1.

In addition, even if the cover main body 32 is detached from the attachment portion 31 at the time of replacement of the filter element 20, the differential pressure sensor 62 is maintained in the attached state to the filter housing 10 side, and therefore maintenance is easy.

According to the present embodiment, by providing the recess 71b in the valve body 71, when the engine is stopped, the working oil in the filter case 10 flows out to the space S3 through the space between the recess 71b and the upper surface 43a, and the air flows in to the spaces S1 and S2 from the space S3 through the hole 32e, so that the oil in the filter element 20 can be removed without detaching the cover body 32 from the attachment portion 31 (synonymous with the filter case 10). Therefore, the working oil can be prevented from dropping (oil dripping) to the outside of the filter device 1 at the time of replacement.

Since the conventional return filter does not have the air discharge holes (the holes 31e and 32e) and the recess 71b, oil does not flow out of the filter case 10 even when the operation of the working machine is stopped, and the oil level is lowered after the cover 30 is removed in the replacement work. Therefore, there is a possibility that oil dripping may occur at the time of replacement of the filter element 20. In contrast, in the present embodiment, since the working oil can be discharged from the filter housing 10 before the replacement operation is performed, the oil in the filter element 20 can be removed in advance before the replacement operation is performed, and therefore, oil dripping can be prevented.

In addition, according to the present embodiment, since the back pressure valve 70 is closed at the time of idling and the back pressure valve 70 is opened after the engine is operated, the air existing inside the filter case 10 is not discharged from the outflow portion 40. Therefore, the generation of air bubbles in the hydraulic oil stored in the tank 100 can be avoided.

If bubbles are contained in the hydraulic oil stored in the tank 100, the bubbles flow into the pump through the suction strainer 50, and corrosion (cavitation) may occur, thereby shortening the life of the pump. In the present embodiment, since the air in the filter case 10 is discharged through the air discharge holes, it is possible to prevent the occurrence of corrosion and the like.

In addition, according to the present embodiment, at the idling time when the flow rate of the hydraulic oil is small, the air does not flow into the filter case 10 through the air discharge hole, and the driving can be stably performed.

In addition, according to the present embodiment, since the bottom surface 44 of the outflow portion 40 covers the upper opening of the filter material 51, the overall length of the filter device 1 in which the reflux filter and the suction strainer are integrated can be shortened.

In the present embodiment, the air outlet hole (holes 31e and 32e) communicates the space S2 with the space S3, but the air outlet hole may not necessarily communicate the space S2 with the space S3. For example, the air discharge hole may communicate the space inside the filter case 10 with the space outside the filter case 10. Even in this case, when the machine of the working machine is stopped, air can be caused to flow into the filter case 10 through the air discharge hole. However, when the hydraulic oil passes through the air outlet hole, it is desirable that both ends of the air outlet hole are open at the lower surface of the lid body 30 so that the hydraulic oil is returned to the tank 100, and the air outlet hole communicates the space S2 with the space S3.

In the present embodiment, the differential pressure sensor 62 is provided in the protruding portion 31a, but various sensors other than the differential pressure sensor 62 may be attached to the protruding portion 31 a. For example, by providing a temperature sensor in the protruding portion 31a, the temperature in the space S2 can be measured.

In the present embodiment, the upper surface 43a and the valve body 71 are flat plates substantially along the horizontal plane, but the shapes of the upper surface 43a and the valve body 71 are not limited to this. For example, the upper surface 43a may have a side surface portion having a truncated cone side surface shape, and the valve body 71 may have a truncated cone side surface shape.

< second embodiment >

Fig. 10 is a cross-sectional view schematically showing a filter device 2 according to an embodiment of the present invention. In fig. 10, hatching showing a cross section is omitted. The same portions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The filter device 2 mainly includes a filter case 10, a filter element 20A, a lid 30A, an outflow portion 40 (see fig. 1), a suction strainer 50 (see fig. 1), and a back pressure valve 70 (see fig. 1).

The filter element 20A mainly includes a filter material 21, an outer cylinder 22, an inner cylinder 23, and plates 24A and 25 (not shown). The lid 30A mainly includes a mounting portion 31, a lid main body 32A, and a cover 33.

The plate 24A is provided at the upper end of the filter 21, the outer cylinder 22, and the inner cylinder 23, and abuts against the lid 30A.

Fig. 11 is a perspective view of the filter device 2 with the cover body 32A and the cover 33 removed. The plate 24A has a substantially cylindrical portion 24A adjacent to the inside of the filter 21 and the inner cylinder 23. The cylindrical portion 24a is provided with a projection 24b projecting radially inward, and the projection 24b is provided with a plurality of holes 24 c.

The explanation returns to fig. 10. The cover body 32A is a substantially thick plate-shaped member, and is provided so as to cover the hollow portion of the mounting portion 31 from above the mounting portion 31. The lid main body 32A mainly includes a flange portion 32A, a first cylindrical portion 32b, a second cylindrical portion 32c, a plate-like portion 32d, and a rib 32g and a protrusion portion 32f provided in the second cylindrical portion 32 c. The rib 32g and the projection 32f are provided so as to protrude downward (-z direction) on the lower surface of the second cylindrical portion 32 c.

Fig. 12 is a perspective view of the cover main body 32A as viewed from below. The rib 32g is a rib having a substantially circular arc shape in plan view. The projection 32f has a shape representing characters, for example. In the present embodiment, the number of the protrusions 32f is 16 (8 × 2 groups), and includes, for example, characters representing "Y", "a", "M", "S", "H", "I", and "N" or shapes of mirror images thereof.

The projection 32f is inserted into the hole 24c formed in the projection 24 b. In other words, the protrusion 32f and the hole 24c have corresponding shapes. In the present embodiment, the hole 24c has a shape including characters "Y", "a", "M", "S", "H", "I", and "N" or a mirror image thereof.

The shape of the projection 32f shown in fig. 12 is an example, and is not limited to this. The plurality of holes 24c and the protrusion 32f may be in the shape of at least one of characters, symbols, and patterns, and mirror images thereof. For example, the hole 24c and the protrusion 32f may be letters, shapes, and the like of a company name of a company that manufactures and sells the filter element 20 or the hydraulic actuator incorporating the filter element 20, a registered trademark, and mirror image letters thereof.

The positions and the number of the projections 24b, the holes 24c, the projections 32f, and the like are not limited to these. In addition, the rib 32g is not essential.

The explanation returns to fig. 10. After the filter element 20A is replaced, a new filter element 20A is inserted into the filter case 10, and then the cover main body 32A is attached to the filter case 10 and the filter element 20A. At this time, the rib 32g is inserted between the protrusions 24b so as to follow the cylindrical portion 24 a. The protrusions 32f are inserted into the corresponding holes 24 c.

According to the present embodiment, it is possible to prevent the use of a filter element other than the filter element 20A that is a certified product.

< third embodiment >

The filter device of the third embodiment differs from the filter device 1 of the first embodiment in the shape of the outflow portion and the back pressure valve. The filter device 3 of the third embodiment mainly includes a filter case 10 (see fig. 1), a filter element 20 (see fig. 1), a lid body 30 (see fig. 1), an outflow portion 40A, a suction strainer 50, and a back pressure valve 70A. The same portions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

Fig. 13 to 15 are schematic cross-sectional views showing the outflow portion 40A, the suction strainer 50, and the back pressure valve 70A in the filter device 3. Fig. 13 and 14 show the case where the back pressure valve 70A is in the closed position. Fig. 15 shows a case where the backpressure valve 70A is in the open position.

The outflow portion 40A communicates the space inside the filter element 20 with the space outside the filter housing 10, and mainly includes a bottom surface 44A, an upper surface 45, and a cylindrical portion 46.

The upper surface 45 is a substantially plate-shaped member, and has a side surface portion 45a having a truncated cone side surface shape. The opening on the lower side of the side surface portion 45a is wide, and the opening on the upper side of the side surface portion 45a is narrow. A flat surface portion 45b is provided at the upper end of the side surface portion 45 a. In addition, a recess 45c is provided at the lower end of the side surface portion 45 a.

The cylindrical portion 46 is substantially cylindrical and provided so as to protrude upward from the upper surface 45. The cylindrical portion 46 is attached to the through hole 14c formed in the filter case 10, whereby the outflow portion 40A is provided in the filter case 10.

The cylindrical portion 46 is provided with a hole 46e defined by a plurality of ribs 46d extending in the radial direction. Further, the upper surface 45 is provided with a hole 45e communicating with the hole 46 e. The holes 45e and 46e are holes through which the working oil flowing out of the space S2 (see fig. 1) flows into the outflow portion 40A. A rod-shaped portion 46f that connects the plurality of ribs 46d is provided substantially at the center of the cylindrical portion 46.

The bottom surface 44A is a substantially plate-shaped member, and a recess 44b is provided at the center. The bottom surface 44A is provided with a rib 44c projecting upward. Further, an inclined surface 44d projecting upward is provided at the upper end of the bottom surface 44A (the surface facing the upper surface 45). The inclined surface 44d is partially missing to form a recess 44 e. The bottom surface of the recess 44e is substantially horizontal.

The bottom surface 44A and the upper surface 45 are integrated by inserting the screw 67 into a hole formed in the bottom surface 45d of the recess 45c and screwing the screw 67 into a hole formed in the rib 44 c. The bottom surface 44A is provided separately from the upper surface 45. The side surface of the outflow portion 40A is open between the bottom surface 44A and the upper surface 45, and this opening is an outflow port 40A through which the hydraulic oil flows out of the outflow portion 40A.

Fig. 16 is a side view schematically showing the outflow portion 40A. An angle θ 1 formed by the side surface portion 45a and the horizontal surface (the planar portion 45b) is approximately 30 degrees. Similarly, the angle θ 1 formed by the inclined surface 44d and the flat surface portion 45b is approximately 30 degrees. In other words, the inclined surface 44d is substantially parallel to the side surface portion 45 a. The angle θ 1 may be equal to or larger than approximately 30 degrees, and may be approximately 45 degrees, for example.

Fig. 17 is a perspective view showing an outline of the outflow portion 40A, and is a view seen through a main part. The inclined surfaces 44d are uniformly arranged in the circumferential direction. Between the adjacent inclined surfaces 44d is a recessed portion 44e, and the recessed portion 44e has a substantially circular sector shape in plan view. In the present embodiment, the bottom surface 44A has three inclined surfaces 44d, and the center angle θ 2 is substantially 120 degrees.

The number of inclined surfaces 44d and the angle of the central angle θ 2 are not limited to these. The recess 44e is not essential, but it is preferable that the bottom surface 44A has the recess 44 e.

The description returns to fig. 13 to 15. The back pressure valve 70A is provided in the outflow portion 40A (i.e., a space between the bottom surface 44A and the upper surface 45). The back pressure valve 70A mainly includes a substantially plate-shaped valve body 71A, an elastic member 72 provided between the valve body 71A and the bottom surface 44A, and a rod-shaped member 73 provided on the rod-shaped portion 46f and the bottom surface 44A.

The rod member 73 is inserted into the recess 44b provided in the bottom surface 44 and into the hole 46g formed in the rod portion 46 f. Further, a hole 71A into which the rod member 73 is inserted is formed in the center of the valve body 71A. Thereby, the rod-like member 73 extends in the vertical direction (z direction).

The elastic member 72 lifts the valve body 71A upward (+ z direction) until the valve body 71A abuts on the upper surface 45. That is, the upper surface 45 functions as a valve seat of the back pressure valve 70. In the closed position where the spool 71A abuts the upper surface 45, the spool 71A covers the hole 45 e. As the pressure inside the filter case 10 increases, the valve body 71A moves downward against the urging force of the elastic member 72. The spool 71A is movable in the z direction along the rod-like member 73 between a closed position where the spool 71A abuts the upper surface 45 and an open position where the spool 71A does not abut the upper surface 45.

The valve body 71A is provided with a flat surface portion 71d on the upper side. Therefore, when the back pressure valve 70A is in the closed state, the upper surface 45 abuts against the flat surface portion 71 d.

Further, in the valve body 71A, a recess 71c is provided in a plane portion 71d which is a surface abutting on the upper surface 45. As shown in fig. 14, even when the back pressure valve 70A is in the closed state, the recess 71c is formed in the valve body 71A, and even when the valve body 71A abuts the upper surface 45, a small space is formed between the recess 71c and the upper surface 45 (the flat surface portion 45 b). As a result, the hole 46e (i.e., the space inside the filter element 20) and the space between the bottom surface 44A and the upper surface 45 (i.e., the space outside the filter housing 10) communicate through the space formed between the recess 71c and the upper surface 45.

Fig. 18 is a diagram showing the flow of the hydraulic oil at the idling time of the engine. In fig. 18, the dashed arrows indicate the flow of the working oil. At the idling speed of the engine, the flow rate of the working oil is small, and is approximately 40L (liters)/min. In this case, although the hydraulic oil gradually flows into the filter case 10 from an inflow portion not shown, the back pressure valve 70A is in a closed state because the pressure inside the filter case 10 has not become sufficiently high because the flow rate of the hydraulic oil is small. When the back pressure valve 70A is in the closed state, the upper surface 45 (the flat surface portion 45b) abuts against the flat surface portion 71d, and therefore a gap exists between the upper surface 45 and the recess portion 71 c. Therefore, the filtered working oil passes through the space between the upper surface 45 and the recess 71c and flows out from the outflow port 40 a.

When the engine is running, the flow rate of the working oil increases, and the flow rate increases to approximately 1000L (liters)/min. In this case, the working oil flows into the filter case 10 (see fig. 1 and 2) from an inflow portion (not shown), the inside of the filter case 10 is filled with the working oil, and the pressure inside the filter case 10 becomes sufficiently high. Therefore, the hydraulic oil presses down the valve body 71A against the urging force of the elastic member 72, and the back pressure valve 70A is opened.

Fig. 19 is a diagram showing the flow of the hydraulic oil when the engine is operating. In fig. 19, solid arrows indicate the flow of the working oil. Since the valve body 71A is separated from the upper surface 45, the hydraulic oil that has passed through the hole 46e and flowed into the hollow portion of the cylindrical portion 46 flows obliquely downward along the side surface portion 45a and flows out from the outlet port 40 a. Since the inclined surface 44d is substantially parallel to the side surface portion 45a, the hydraulic oil flows obliquely downward along the inclined surface 44 d.

The inclined surface 44d is partially missing and forms a recess 44 e. Therefore, the volume between the bottom surface 44 and the upper surface 45 is increased, and the flow rate of the working oil flowing between the bottom surface 44 and the upper surface 45 can be increased. Therefore, even when the engine is operated and the working oil flows in a large amount, the flow of the working oil is not hindered.

When the engine is stopped, as shown in fig. 18, the backpressure valve 70A returns to the closed state. Since the recess 71c is formed in the valve body 71A, the working oil in the filter case 10 flows out to the space S3 (see fig. 1) through the space between the recess 71c and the upper surface 45, and the air flows in from the space S3 to the spaces S1 and S2 (see fig. 1) through the hole 32e (see fig. 1), so that the oil in the filter element 20 can be removed without removing the cover body 32 (see fig. 1).

According to the present embodiment, by providing the recess 71c in the valve body 71A, the hydraulic oil can be made to flow out of the filter case 10 through the space between the recess 71c and the upper surface 45 even when the back pressure valve 70A is in the closed state.

Further, according to the present embodiment, since the side surface portion 45a has a truncated cone side surface shape, the hydraulic oil can be caused to flow obliquely downward along the side surface portion 45a when the back pressure valve 70A is in the open state. For example, when the hydraulic oil flows out in the lateral direction, the hydraulic oil flowing out from the outflow portion collides with the side surface of the tank 100, and causes various problems (for example, fluctuation in the oil level and generation of bubbles). In contrast, by flowing the hydraulic oil obliquely downward, the hydraulic oil can be prevented from colliding with the side surface of tank 100, and a problem caused by the collision of the hydraulic oil with the side surface of tank 100 can be prevented.

In order to facilitate the working oil to flow obliquely downward along the side surface portion 45a, according to the present embodiment, the outflow port 40A is provided on the side surface of the outflow portion 40A.

< fourth embodiment >

The filter device 4 of the fourth embodiment is a detachable return filter. The filter device 4 is a device in which a reflux filter and a suction strainer are integrated, and is provided in the tank 100. Fig. 20 and 21 are sectional views schematically showing the filter device 4. The difference between fig. 20 and 21 is the overall length of the filter device 3 (described in detail below). In fig. 20 and 21, hatching showing cross sections is partially omitted.

The filter device 4 mainly includes a filter case 10A, a filter element 20, a lid 30B, an outflow portion 40B, a suction strainer 50A, and a back pressure valve 70A. The same parts as those in the first to third embodiments are denoted by the same reference numerals, and descriptions thereof are omitted.

The filter case 10A has a substantially cylindrical shape with a bottom, and an upper end surface is open. The substantially cylindrical shape is a concept including a substantially cylindrical shape, a substantially elliptical cylindrical shape, and the like, but in the present embodiment, a substantially cylindrical shape is illustrated.

The filter housing 10A mainly has a first housing 11 of a substantially cylindrical shape, a second housing 12 of a substantially cylindrical shape, a third housing 14, an inner housing 15A, and a mounting member 16. A second housing 12 is provided on the upper side of the first housing 11, and a mounting member 16 is provided on the second housing 12. A third housing 14 and an inner housing 15 are provided below the first housing 11.

A through hole 14c is formed in the bottom surface 14a of the third housing 14. The through hole 14c is provided with an outflow portion 40B via the mounting member 17. However, the mounting member 17 is not essential. The outflow portion 40B communicates the space inside the filter element 20 with the space outside the filter housing 10. The outflow portion 40B will be described later in detail.

Inner case 15A is provided inside third case 14, and divides the space inside third case 14 into two parts. The inner housing 15A has an outer cylindrical portion 15d and an inner cylindrical portion 15 e. The cylindrical portion 15d is provided with a hole 15c into which the inflow tube 106 is inserted. The cylindrical portion 15e is provided with a valve 61.

The lid 30A is provided outside the tank 100 (above the upper surface 101 in the present embodiment). The lid 30 is provided to the filter case 10A (the attachment member 16) and the filter element 20 (the plate 24) so as to cover the opening portion of the upper end surface of the filter case 10A.

Fig. 22 is a perspective view showing the vicinity of the lid 30B in an enlarged manner. In fig. 22, a part is shown in cross section, and hatching showing the cross section is omitted. The lid 30B mainly includes a mounting portion 31A, a lid main body 32B, and a cover 33.

The mounting portion 31A is substantially cylindrical, and is fixed to the mounting member 16 by a screw (not shown in fig. 22). Similarly to the mounting portion 31, the mounting portion 31A has a protruding portion 31A and a hole 31b, and the hole 31b is provided with a differential pressure sensor 62 (see fig. 20 and 21).

The mounting portion 31A has a plurality of holes 31e as a part of the air discharge hole. The lower surface (-z-side surface) of the mounting portion 31A has a substantially annular groove 31f in plan view connecting the plurality of holes 31 e. One end of the hole 31e opens into the inner peripheral surface 31g, and the other end opens into the groove 31 f.

The cover body 32B is a substantially thick plate-shaped member, and is provided so as to cover the hollow portion of the mounting portion 31A from above the mounting portion 31A. The cover main body 32B is fixed to the mounting portion 31A by screws 66.

The cap main body 32B includes a cylindrical portion 32o protruding upward, and a flange portion 32p provided outside the cylindrical portion 32 o. A cover 33 is provided above the cylindrical portion 32 o. Flange portion 32p abuts mounting portion 31A. Sealing members 81 and 82 for preventing leakage of the working oil are provided between the mounting portion 31A and the cover main body 32B.

The cap main body 32B has a first protrusion 32h of a substantially cylindrical shape disposed below the cylindrical portion 32 o. The side surface of the first projecting portion 32h abuts against the inner peripheral surface 31g of the mounting portion 31A.

The first projection 32h has a flat surface 32i at the front end (-z-side end). The flat surface 32i abuts the upper surface 24d of the plate 24. In addition, the first projection 32h has a second projection 32j at a central portion of the leading end (-z-side end). The second projecting portion 32j is inserted into the cylindrical portion 24a, and the side surface of the second projecting portion 32j abuts against the inner peripheral surface 24e of the plate 24 (the cylindrical portion 24 a).

The first projection 32h and the second projection 32j have a hole 32k, a hole 32m (see fig. 20 and 21), and a recess 32n, which are parts of the air discharge hole 39A as channels for air and hydraulic oil. The cavity 32k is an open end of the air discharge hole 39A, and has a substantially conical shape or a substantially truncated conical shape whose inner diameter decreases as going upward. The concave portion 32n is provided on the outer peripheral surface of the first protruding portion 32h, and is recessed in the radial direction.

The cavity 32k and the recess 32n communicate with each other through a cavity 32m (see fig. 20 and 21). Further, the recess 32n communicates with the hole 31 e. The groove 31f communicates with the hole 16a (see fig. 20 and 21) of the mounting member 16. Therefore, the air outlet hole 39A having the hole 31e, the groove 31f, the pocket 32k, the pocket 32m, the recess 32n, and the hole 16a communicates the space S2 inside the filter element 20 with the space S3 outside the filter case 10A.

The explanation returns to fig. 20 and 21. The outflow portion 40B is provided below the filter case 10A so as to cover the through-hole 14c provided in the bottom surface 14a of the third case 14. The outflow portion 40B communicates the space S2 with the space S3. A suction strainer 50A is provided below the outflow portion 40B.

An elastic member 47 is provided between the outflow portion 40B and the suction strainer 50A. The elastic member 47 is elastically deformed according to the height of the tank 100, the filter case 10A, the suction strainer 50A, and the like, thereby changing the distance between the outflow portion 40B and the suction strainer 50A. Fig. 20 shows an example in which the distance between the outflow portion 40B and the suction strainer 50A is short, and the amount of deformation of the elastic member 47 is large. Fig. 21 shows an example in which the distance between the outflow portion 40B and the suction strainer 50A is long, and the amount of deformation of the elastic member 47 is small. In this way, by providing the elastic member 47 between the outflow portion 40B and the suction strainer 50A, the height of the outflow portion 40B relative to the suction strainer 50A can be easily adjusted.

Next, the outflow portion 40B and the suction strainer 50A will be explained. Fig. 23 and 24 are cross-sectional views schematically showing the outflow portion 40B, the suction strainer 50A, and the back pressure valve 70A. Fig. 23 shows a case where the backpressure valve 70A is in a closed state, and fig. 24 shows a case where the backpressure valve 70A is in an open state. In fig. 23 and 24, hatching showing cross sections is omitted.

The outflow portion 40B mainly has a bottom surface 44B, an upper surface 45, and a cylindrical portion 46A.

The cylindrical portion 46A is substantially cylindrical and provided so as to protrude upward from the upper surface 45. The cylindrical portion 46A is attached to the filter case 10, whereby the outflow portion 40B is provided in the filter case 10. The cylindrical portion 46A differs from the cylindrical portion 46 only in the presence or absence of a screw formed on the outer peripheral surface, and the other points are the same.

The bottom surface 44B includes a substantially hollow disk-shaped plate-shaped portion 44f, a cylindrical portion 44g protruding downward from the plate-shaped portion 44f substantially along the inner peripheral surface of the plate-shaped portion 44f, and a bottom surface 44h covering the lower end surface of the cylindrical portion 44 g. The cylindrical portion 44g does not necessarily need to substantially follow the inner peripheral surface of the plate-like portion 44 f. An inclined surface 44d projecting upward is provided at the upper end (the surface facing the upper surface 45) of the plate-like portion 44 f. The inclined surface 44d is partially missing to form a recess 44 e.

A bar member 73 is provided in the hole 44i formed in the bottom surface 44 h. Thus, the back pressure valve 70A is provided in the outflow portion 40B. The rod-like member 73 extends in the vertical direction (z direction).

The bottom surface 44B and the upper surface 45 are integrated by screws 67. The bottom surface 44B is provided separately from the upper surface 45. The side surface of the outflow portion 40B is open between the bottom surface 44B and the upper surface 45, and this opening is an outflow port 40a through which the hydraulic oil flows out of the outflow portion 40B.

One end of the elastic member 47 abuts on a lower surface of the bottom surface 44 h. Therefore, the outflow portion 40B is urged upward by the elastic member 47.

The suction strainer 50A mainly includes a filter material 51, a mounting member 52, a plate-like member 53, a claw 54, and an inner cylinder 55. The plate-like member 53 is provided on the upper side of the filter material 51 so as to cover the hollow portion of the filter material 51. The inner cylinder 55 is provided along the inner peripheral surface of the filter material 51.

Fig. 25 is a view showing an outline of the suction strainer 50A, where (a) is a plan view and (B) is a sectional view.

The plate-like member 53 mainly includes an upper end portion 53a covering the upper end surface of the filter material 51, a cylindrical portion 53b protruding downward from the upper end portion 53a, a bottom surface portion 53c, and a side surface portion 53d connecting the cylindrical portion 53b and the bottom surface portion 53 c.

The cylindrical portion 53b has a substantially cylindrical shape and a larger diameter than the cylindrical portion 44g (see fig. 23 and 24). The bottom surface portion 53c has a substantially bottomed cylindrical shape, and abuts against one end of the elastic member 47. Therefore, the suction strainer 50A is urged downward by the elastic member 47.

The upper end portion 53a is provided with a claw 54. The claw 54 protrudes radially inward from the upper end portion 53a and the cylindrical portion 53 b. The claw 54 is a plate spring formed by bending a plate-shaped member such as a metal, and has elasticity.

In the present embodiment, the claw 54 is provided at the upper end portion 53a, but the position at which the claw 54 is provided is not limited to this, and the claw 54 may be provided on the inner circumferential surface of the cylindrical portion 53 b. The claw 54 is a member different from the plate-like member 53, but the plate-like member 53 and the claw 54 may be integrated. The claw 54 may have elasticity, and may be formed of an elastic member such as rubber.

The explanation returns to fig. 23 and 24. A groove 44j is formed in the outer peripheral surface of the cylindrical portion 44 g. When the cylindrical portion 44g is inserted inside the cylindrical portion 53b, the claw 54 abuts on the groove 44 j. Then, the claw 54 presses the bottom surface of the groove 44j (the outer peripheral surface of the cylindrical portion 44 g) by the elastic force of the claw 54, and the bottom surface 44B is provided on the plate-like member 53.

Fig. 26 is a view showing an outline of the bottom surface 44B, where (a) is a cross-sectional view and (B) is a perspective view. Fig. 26 (a) shows a state when the cross section of the bottom surface 44B at the line a-a of fig. 26 (B) is viewed from the + z direction.

The groove 44j includes a horizontal groove 44k extending substantially in the horizontal direction and vertical grooves 44m and 44n connected to both ends of the horizontal groove 44 k. The vertical grooves 44m, 44n extend downward in the vertical direction from the horizontal groove 44 k. The lower end of the vertical groove 44m reaches the lower end of the cylindrical portion 44g, and the lower end of the vertical groove 44n does not reach the lower end of the cylindrical portion 44 g.

Here, a method of attaching the outflow portion 40B (the bottom surface 44B) to the suction strainer 50A will be described. First, when the cylindrical portion 44g is inserted into the cylindrical portion 53b, the vertical groove 44m and the claw 54 are aligned in position in a plan view (when viewed from the + z direction). The bottom surface 44B is pressed against the urging force of the elastic member 47, and the claw 54 is moved along the vertical groove 44m while moving the bottom surface 44B in the-z direction. Then, the height of the horizontal groove 44k is made equal to the height of the claw 54, and the bottom surface 44B is rotated in the circumferential direction to move the claw 54 along the horizontal groove 44k, and the position of the vertical groove 44n is made equal to the position of the claw 54 in a plan view.

Then, when the force pressing down the bottom surface 44B is removed, the bottom surface 44B is lifted by the force of the elastic member 47, so that the bottom surface 44B moves to the + z direction. Then, the claw 54 moves along the vertical groove 44 n. The bottom surface 44B is not pulled out because the lower end of the vertical groove 44n does not reach the lower end of the cylindrical portion 44 g.

According to the present embodiment, since the elastic member 47 is provided between the outflow portion 40B and the suction strainer 50A, the entire length of the filter device 3 can be adjusted.

In addition, according to the present embodiment, since the plate-shaped member 53 is provided on the filter material 51 and the outflow portion 40B and the suction strainer 50A are separate members, the outflow portion 40B and the suction strainer 50A can be detachably attached.

Further, according to the present embodiment, the claw 54 presses the outer peripheral surface of the cylindrical portion 44g by the elastic force of the claw 54, so that the outflow portion 40B and the suction strainer 50A can be detachably attached, and the outflow portion 40B can be reliably attached to the plate-like member 53.

Further, according to the present embodiment, when the outflow portion 40B is attached to the suction strainer 50A, the outflow portion 40B can be reliably attached to the suction strainer 50A by pressing and rotating the outflow portion 40B and moving the claw 54 along the groove 44 j. Further, since the lower end of the vertical groove 44n does not reach the lower end of the cylindrical portion 44g, the outflow portion 40B does not come out of the suction strainer 50A when the overall length of the filter device 3 is adjusted by the elastic member 47.

In addition, according to the present embodiment, since the cavity 32k, which is the opening end of the air discharge hole 39A, is formed in a substantially conical shape or a substantially truncated conical shape whose inner diameter becomes smaller as going upward, air bubbles generated inside the filter element 20 are easily collected. Further, the air bubbles collected inside the cavity 32k are collected in a narrow area as they go upward, and therefore the air bubbles are easily discharged from the air discharge hole 39A.

In the present embodiment, the groove 44j is provided on the outer peripheral surface of the cylindrical portion 44g, and the outflow portion 40B is pressed and rotated to move the claw 54 along the groove 44j, whereby the outflow portion 40B is attached to the suction strainer 50A.

Fig. 27 is a view showing an outline of the outflow portion 40C of the modification, (a) is a side view, and (B) is a cross-sectional view. Fig. 27 (B) shows a state when the cross section of the bottom surface 44C at the line B-B of fig. 27 (a) is viewed from the + z direction.

The outflow portion 40C mainly has a bottom surface 44C, an upper surface 45, and a cylindrical portion 46A. The bottom surface 44C includes a substantially hollow disc-shaped plate portion 44f, a cylindrical portion 44p protruding downward from the plate portion 44f, and a bottom surface 44h covering a lower end surface of the cylindrical portion 44 p.

A recess 44q is formed along the circumferential direction on the outer circumferential surface of the cylindrical portion 44 p. The recess 44q does not reach the lower end of the cylindrical portion 44p, and a protrusion 44r is formed at the lower end of the cylindrical portion 44 p.

When the outflow portion 40C (the bottom surface 44C) is attached to the suction strainer 50A, the outflow portion 40C is pressed down, and the cylindrical portion 44p is inserted into the cylindrical portion 53b (see fig. 25). Then, the claw 54 is deformed to go over the projection 44r, and the claw 54 abuts on the recess 44 q. Then, the claw 54 presses the outer peripheral surface of the recess 44q by the elastic force of the claw 54, and the bottom surface 44C is provided on the plate-like member 53.

According to the present modification, the outflow portion 40C can be attached to the suction strainer 50A in one operation without pressing and rotating the outflow portion 40C when attaching the outflow portion 40C. Further, the bottom surface 44C can be formed in a simple shape.

In the present modification, since the outflow portion 40C does not need to be pressed and rotated, the bottom surface 44C and the cylindrical portion 53b of the plate-like member 53 may be substantially cylindrical, and may not be substantially cylindrical.

While the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the embodiments, and design changes and the like are included without departing from the scope of the present invention. For example, the above-described embodiments have been described in detail to explain the present invention in an easily understandable manner, but the present invention is not necessarily limited to the embodiments having all the configurations described. Further, a part of the configuration of the embodiment may be replaced with the configuration of another embodiment, and the configuration of the embodiment may be added, deleted, replaced, or the like with respect to another configuration.

"substantially" is a concept including not only strictly the same cases but also errors and variations to the extent that identity is not lost. For example, the "substantially cylindrical shape" is a concept including not only a case of being strictly cylindrical but also a case of being equally viewable with a cylindrical shape, for example. For example, when only the terms orthogonal, parallel, and uniform are used, the terms include not only the cases of being strictly orthogonal, parallel, and uniform, but also the cases of being substantially parallel, substantially orthogonal, and substantially uniform.

The term "vicinity" refers to a region including a certain range (which can be arbitrarily specified) in the vicinity of a reference position. For example, the term "near the end" refers to a certain range of the area near the end, and is a concept that may or may not include the end.

Description of the reference numerals

1. 2, 3, 4: filter device

10. 10A: filter casing

10 a: upper end part

11: first shell

12: second shell

12 a: small diameter part

13: mounting part

13 a: plate-shaped part

14: third casing

14 a: bottom surface

14 b: hole(s)

14 c: through hole

15. 15A: inner shell

15a, 15b, 15d, 15 e: cylindrical part

15 c: hole(s)

16: mounting member

16 a: hole(s)

17: mounting member

20. 20A: filter element

21: filter material

22: outer cylinder

23: inner cylinder

24. 24A, 25: board

24 a: cylindrical part

24 b: protrusion part

24 c: hole(s)

24 d: upper surface of

24 e: inner peripheral surface

25: board

30. 30A, 30B: cover body

31. 31A: mounting part

31 a: projection part

31 b: acupoints

31c, 31 e: hole(s)

31 f: trough

31 g: inner peripheral surface

32. 32A, 32B: cover main body

32 a: flange part

32 b: a first cylindrical part

32c, the ratio of: a second cylindrical part

32 d: plate-shaped part

32e, and (3): hole(s)

32 f: protrusion part

32 g: ribs

32 h: first protruding part

32 i: flat surface

32 j: second protrusion

32 k: acupoints

32 m: acupoints

32 n: concave part

32 o: cylindrical part

32p of: flange part

33: cover

39. 39A: air discharge hole

40. 40A, 40B, 40C: outflow part

40 a: outflow opening

41. 42: cylindrical part

43: connecting part

43 a: upper surface of

43 b: cylindrical part

43 c: outflow opening

43 d: ribs

43e, 43g, 43 h: hole(s)

43 f: rod-shaped part

44. 44A, 44B, 44C: bottom surface

44 a: ribs

44 b: concave part

44 c: ribs

44 d: inclined plane

44e, the ratio of: concave part

44 f: plate-shaped part

44g, 44 p: cylindrical part

44 h: bottom surface

44 i: acupoints

44j, and (b): trough

44k, and (3) is as follows: horizontal groove

44m, 44 n: plumb trough

44 q: concave part

44 r: protrusion

45: upper surface of

45 a: side surface part

45 b: plane part

45 c: concave part

45 d: bottom surface

45 e: hole(s)

46: cylindrical part

46 d: ribs

46 e: hole(s)

46 f: rod-shaped part

46 g: hole(s)

47: elastic member

50. 50A: suction type coarse filter

51: filter material

52: mounting member

53: plate-like member

53 a: upper end part

53 b: cylindrical part

53 c: bottom surface part

53 d: side surface part

54: claw

55: inner cylinder

61: valve with a valve body

62: differential pressure sensor

65. 66, 67: screw nail

70. 70A: back pressure valve

71. 71A: valve core

71 a: hole(s)

71b, 71 c: concave part

71 d: plane part

72: elastic member

73: rod-like member

81. 82, 83: sealing member

100: pot for storing food

101: upper surface of

101 a: opening part

102: bottom surface

102 a: outflow opening

105: mounting plate

105 a: gap

106: and an inflow pipe.