CN111828413A - Filter device - Google Patents

Abstract

The invention relates to a filter device, which can prevent liquid from dropping outside when a filter element is replaced. The outflow portion that communicates the space inside the filter element with the space outside the filter housing 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 body is movable between a closed position where the valve body and the upper surface abut and an open position where the valve body and the upper surface do not abut. A recess is provided on a surface of the valve body which abuts the upper surface, an outlet port is formed at a position overlapping the recess in a plan view of the upper surface, and a space formed between the recess and the upper surface communicates a space inside the filter element with a space outside the filter case at the closed position.

Description

Filter device

Technical Field

The present invention relates to a filter device.

Background

Patent document 1 discloses a liquid filter having a check valve for shutting off 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 when the internal combustion engine is stopped. Therefore, when the internal combustion engine is stopped and the filter element is replaced, the liquid enclosed 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 provided in, for example, a tank for storing a liquid, and includes: a filter case mounted on the tank and having a substantially bottomed cylindrical shape with an open upper end; a filter element provided in the filter housing and having a substantially cylindrical filter medium; a cover body that is provided on the filter case and the filter element so as to cover an upper end of the filter case, and that has an exhaust hole that communicates a space inside the filter element with a space outside the filter case; an inflow portion that causes 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 having an upper surface and a bottom surface which are separately provided, and a cylindrical portion which is provided so as to protrude upward from the upper surface and is attached to a through hole formed in the filter housing, the cylindrical portion and the upper surface being provided with a hole through which the liquid passes, the back pressure valve having a substantially plate-shaped valve body which is movable between a closed position in which the valve body is in contact with the upper surface and an open position in which the valve body is not in contact with the upper surface, a recess being provided in a surface of the valve body in contact with the upper surface, an outlet being formed in a position overlapping the recess when the upper surface is viewed in plan, and a space being formed between the recess and the upper surface in the closed position, communicating a space inside the filter cartridge with a space outside the filter housing.

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 case 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 body is movable between a closed position where the valve body and the upper surface abut and an open position where the valve body and the upper surface do not abut. A recess is provided on a surface of the valve body which abuts the upper surface, an outlet port is formed at a position overlapping the recess in a plan view of the upper surface, and a space formed between the recess and the upper surface communicates a space inside the filter element with a space outside the filter case at the closed position. Therefore, when the engine is stopped, the liquid can flow out of the filter case without detaching the cover from the filter case, thereby draining the oil in the filter element. This prevents hydraulic oil from dropping to the outside of the filter device (oil dripping) during replacement. Further, since the air in the filter case is discharged through the air discharge hole, occurrence of cavitation and the like can be prevented.

Here, the filter case may be provided inside the tank, the lid may be provided on an upper side of the tank, and both ends of the exhaust hole may be opened on a surface of a lower side of the lid to communicate a space inside the filter element with a space outside the filter case and inside the tank. Thereby, even if the hydraulic oil passes through the exhaust hole, the hydraulic oil can be returned to the tank.

Here, a portion of the filter case adjacent to the upper end opening may be constricted. Accordingly, when the liquid passes through the air vent hole, the liquid flows into the tank along the filter case, and therefore, bubbles can be prevented from being generated in the liquid stored in the tank.

Here, the tank may have a substantially cylindrical second filter unit, an upper side of the second filter unit may be covered with the bottom surface, a lower side of the second filter unit may be provided with a mounting member, and the second filter unit may be provided on the tank via the mounting member. This can shorten the overall length of the filter device in which the reflux filter and the suction filter are integrated.

Here, the filter element may have an upper plate provided at an upper end of the filter medium, a protrusion protruding downward may be formed on a rear surface of the cover, and a hole into which the protrusion is inserted may be formed in the upper plate. This prevents the use of a filter cartridge other than the standard product.

Effects of the invention

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

Drawings

Fig. 1 is a sectional view showing an outline of a filter device 1 as an embodiment of the present invention.

Fig. 2 is an enlarged view showing 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 filter 50.

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

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

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

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

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

Fig. 10 is a sectional view showing an outline of a filter device 2 as an embodiment of the present invention.

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

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

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, the hydraulic oil is taken as an example of the liquid to be filtered, but the liquid to be filtered is not limited to the hydraulic 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 sectional view showing an outline of a filter device 1 as 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 filter are integrated. The filter device 1 is provided on the tank 100. The tank 100 is a tank for storing hydraulic oil, and is, for example, box-shaped. The tank 100 is a device 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 within the hydraulic circuit.

An opening 101a for attaching the filter device 1 is formed in the upper surface 101 of the tank 100. The filter device 1 is mounted on the upper surface 101 via a mounting plate 105 (see fig. 3). However, the mounting plate 105 is not required.

A substantially cylindrical inflow pipe 106 for allowing 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 hydraulic oil from the outside of the tank 100 to the filter device 1. The hydraulic oil introduced to the filter device 1 is filtered by the filter device 1 and then stored in the tank 100.

An outlet 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 filter 50 is provided inside the tank 100, and the hydraulic oil that has passed through the suction filter 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, and a suction filter 50.

The filter case 10 is formed of a material having high corrosion resistance (for example, a metal such as stainless steel). The filter case 10 is provided inside the tank 100 so as to protrude downward (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 thereof is open. The filter case 10 has a hollow interior, 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, and the substantially cylindrical shape is illustrated in the present embodiment.

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. The second housing 12 and the mounting portion 13 are provided on the upper side (+ z side) of the first housing 11. The mounting portion 13 is a member for mounting the filter case 10 on the upper surface 101 of the tank 100, and includes a plate-like portion 13a mounted on the lid 30 and a cylindrical portion 13b provided below the plate-like 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.

A third housing 14 and an inner housing 15 are provided on the lower side of 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 outflow portion 40 is provided so as to cover the through hole 14 c. 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 outside the side surface of the third housing 14, and the through hole 14c may be provided outside the bottom surface 14 a.

The portion of the filter case 10 adjacent to the upper end opening is an upper end portion 10a, and here corresponds to a small diameter portion 12a and a 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 case 10 is constricted.

The inner case 15 is a member that divides the space in the third case 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 filter case 10 and a space (space S1) outside the filter element 20. The cylindrical portion 15b is provided with a valve 61.

Normally, the valve 61 is closed, but when the pressure in the filter case 10 rises due to the clogging of the filter medium 21, the valve 61 is opened, and the hydraulic oil is caused to flow 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 known, and therefore, the description thereof 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 medium 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 medium 21.

The filter medium 21 is a substantially cylindrical member having openings at both ends. The filter medium 21 is formed by pleating and folding filter paper using synthetic resin, paper, or the like, and connecting both ends of the pleated filter paper to each other and rolling the filter paper into a cylindrical shape. An outer cylinder 22 is provided outside the filter medium 21, and the outer cylinder 22 has a hole through which the hydraulic oil passes over substantially the entire area. Further, an inner cylinder 23 is provided inside the filter medium 21, and a hole through which the hydraulic oil passes is formed substantially over the entire area of the inner cylinder 23.

A plate 24 is provided at the upper end of the filter medium 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 medium 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 disposed on the filter housing 10.

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

Fig. 2 is an enlarged view showing the vicinity of the upper end of the filter device 1. Fig. 3 is a cut-away perspective view of the filter device 1. In fig. 2 and 3, the hatching showing the cross section is omitted.

The lid body 30 mainly has a mounting portion 31, a lid main body 32, and a lid 33.

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

The cover body 32 is a substantially thick plate-like member provided 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, 82 for preventing leakage of the hydraulic oil are provided between the mounting portion 31 and the cover main body 32.

The cover main body 32 mainly has: the flange portion 32 a; a substantially cylindrical first cylindrical portion 32b disposed inside the flange portion 32 a; a second cylindrical portion 32c having a substantially closed-end cylindrical shape and disposed inside the first cylindrical portion 32 b; and a substantially plate-like portion 32d that connects 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-shaped portion 32d abuts against the plate 24, and the second cylindrical portion 32c is inserted into the inner cylinder 23.

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 opens toward the hole 31b, communicating the hole 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, thereby detecting a difference between the pressure inside the filter case 10 and the pressure outside the case.

The hole 32e communicates with a hole 31e formed on the mounting portion 31. The holes 31e and 32e are exhaust holes, and both ends thereof are open on the surface of the lower side of the lid body 30. The holes 31e and 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 case where these components are not provided, the hole 31e and the hole 32e directly communicate the space S2 and the space S3.

A cover 33 is provided on the cover main body 32. The cover 33 is a substantially plate-like member, and is provided on the upper side of the cover main body 32. The cover main body 32 and the cover 33 may be one member.

Returning to the description of 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 filter 50 is provided below the outflow portion 40.

Fig. 4 is a perspective view of the outflow portion 40 and the suction filter 50. Fig. 5 and 7 are sectional perspective views of the outflow portion 40 and the suction filter 50. Fig. 6 and 8 are sectional views of the outflow portion 40 and the suction filter 50. In fig. 5 to 8, the hatching showing the cross section is 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 inserted into the cylindrical portion 41. The cylindrical portion 41 and the cylindrical portion 43b are inserted into the through hole 14c of the third housing 14, and the cylindrical portion 41 and the cylindrical portion 43b, that is, the outflow portion 40 are attached to the filter housing 10.

An outlet port 43c through which hydraulic oil passes is provided on the upper surface 43 a. The outlet 43c is disposed at a position overlapping the recess 71b (described later in detail) in a plan view (viewed from the z direction).

The cylindrical portion 43b is provided with holes 43e partitioned by a plurality of ribs 43d extending in the radial direction. The hollow portions of the hole 43e and the cylindrical portion 43b are holes through which the hydraulic oil flowing out of the space S2 passes. 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 protruding 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 backpressure valve 70 is provided in a space between the upper surface 43a and the bottom surface 44. The back pressure valve 70 mainly has: 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 provided on the rod portion 43f and the bottom surface 44.

Fig. 5 and 6 show the valve body 71 in the closed position where the valve body 71 abuts the upper surface 43 a. Fig. 7 and 8 show the valve body 71 in the open position where the valve body 71 does not abut the upper surface 43 a.

The rod member 73 is inserted into the recess 44b provided on the bottom surface 44, and is inserted into the hole 43g formed on 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 valve body 71 is movable in the z direction between a closed position and an open position along the rod member 73.

The elastic member 72 pushes up the valve body 71 upward (+ z direction). The elastic member 72 pushes up 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. As the pressure inside the filter case 10 increases, the valve body 71 moves downward against the urging force of the elastic member 72.

A recess 71b is provided on the surface of the valve body 71 abutting the upper surface 43 a. Fig. 9 is a cross-sectional view of the outflow portion 40 and the back pressure valve 70 when the valve body 71 is at the closed position (the back pressure valve 70 is in the closed state). By forming the recess 71b in the valve body 71, even if the valve body 71 abuts on the upper surface 43a, a minute space is formed between the recess 71b and 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 via 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.

Returning to the description of fig. 4 to 8. The suction filter 50 has a substantially cylindrical filter medium 51. The filter medium 51 is a filter unit through which the hydraulic oil can pass. The opening on the upper side of the filter medium 51 is covered with the bottom surface 44. An attachment member 52 is provided below the filter medium 51. The attachment member 52 is configured to attach the filter medium 51 to the bottom surface 102 such that the suction filter 50 covers the outlet port 102 a. A sealing member 83 is provided between the mounting member 52 and the outlet port 102a to prevent leakage of the hydraulic oil.

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

When the operation of the engine of the working machine is stopped, the filter case 10 does not contain hydraulic oil. Therefore, as shown in fig. 1, the backpressure valve 70 is in a closed state, and the space S2 and the space S3 are not communicated through the outflow portion 40.

When the work machine starts to be driven, as shown in fig. 1, the hydraulic oil starts to flow in the hydraulic circuit, and accordingly, the hydraulic oil gradually flows into the space S1. Since the filter case 10 (spaces S1 and S2) is filled with the initial air, the initial air is discharged to the space S3 through the air discharge hole (hole 31e (not shown in fig. 1) and hole 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 to the inside of the filter medium 21, and dust and the like in the hydraulic oil are removed by the filter medium 21. The filtered hydraulic oil flows out to the space S2.

At engine idle, the flow of hydraulic oil is small, approximately 40L (liters) per minute. In this case, although the hydraulic oil gradually flows into the filter case 10 from an inflow portion not shown, the back pressure valve 70 is in a closed state as shown in fig. 1 because the pressure inside the filter case 10 does not sufficiently increase due to a small flow rate of the hydraulic oil. As a result, the oil level rises to the position of the oil level L indicated by the broken line. In addition, since the back pressure valve 70 is in the closed state at the time of 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 hydraulic oil becomes large, and the flow rate increases to approximately 1000L (liters)/minute. In this case, the hydraulic oil flows into the filter case 10 from an inflow portion not shown, the filter case 10 is filled with the hydraulic oil, and the pressure inside the filter case 10 becomes sufficiently high. Therefore, as shown in fig. 7, the back pressure valve 70 is in an open state by the hydraulic oil pressing the valve body 71 against the urging force of the elastic member 72. As a result, the filtered hydraulic oil flows out to the space S3 through the outflow portion 40.

During the operation of the engine, the interior of the filter case 10 is filled with the hydraulic oil, and therefore flows out to the space S3 through the exhaust hole (the hole 31e and the hole 32 e). Since the upper end portion 10a of the filter case 10 is constricted, the liquid passing through the gas discharge hole is not directly dropped into the liquid 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.

The hydraulic oil flowing out to the space S3 flows out to the outside of the tank 100 from the outflow port 102a via the suction filter 50.

When the engine is stopped, air flows from the space S3 into the spaces S1 and S2 through the hole 32 e. As shown in fig. 9, the filtered hydraulic oil flows out to the space S3 through between the concave portion 71b and the upper surface 43 a. Thus, the oil level gradually lowers even if the cover body 32 is not removed from the attachment portion 31 (as in the filter case 10). Therefore, when a certain time (for example, about 5 minutes) has elapsed since the work machine was stopped, the oil level becomes lower than the plate 25 without detaching the cover main 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 can be pulled out from the open end of the upper portion of the filter housing 10. Since the oil level is lower than the plate 25 after a certain time has elapsed from the stop of the working machine, the filter element 20 is not immersed in the hydraulic oil, and the used filter element 20 in a state in which the oil is drained can be pulled out. As a result, hydraulic oil droplets can be prevented from falling outside the filter device 1.

Further, even if the cover body 32 is detached from the attachment portion 31 when replacing the filter element 20, the differential pressure sensor 62 is attached to the filter case 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 hydraulic oil in the filter case 10 flows out to the space S3 through between the recess 71b and the upper surface 43a, and the air flows in from the space S3 to the spaces S1 and S2 through the air passage hole 32e, so that the oil in the filter element 20 can be drained without detaching the cover main body 32 from the attachment portion 31 (as in the case of the filter case 10). Therefore, hydraulic oil can be prevented from dropping to the outside of the filter device 1 (oil dripping occurs) at the time of replacement.

Since the vent holes ( holes 31e and 32e) and the recess 71b are not formed in the conventional return filter, oil does not flow out of the filter case 10 even when the operation of the working machine is stopped, and the oil level can be lowered only by removing the lid body 30 during the replacement work. Therefore, oil dripping may occur when the filter element 20 is replaced. In contrast, in the present embodiment, since the hydraulic oil can be discharged from the filter case 10 before the replacement work is performed, the oil in the filter element 20 can be drained before the replacement work is performed, and therefore, oil dripping can be prevented.

Further, according to the present embodiment, the back pressure valve 70 is closed at the time of idling, and the back pressure valve 70 is opened only after the engine is operated, so that the air in the filter case 10 is not discharged from the outflow portion 40. Therefore, it is possible to prevent air bubbles from being generated in the hydraulic oil stored in the tank 100.

If air bubbles are contained in the hydraulic oil stored in the tank 100, the air bubbles flow into the pump through the suction filter 50, cavitation occurs, and the life of the pump may be shortened. In the present embodiment, since the air in the filter case 10 is discharged through the air discharge hole, occurrence of cavitation erosion and the like can be prevented.

Further, according to the present embodiment, at the time of idling where the flow rate of the hydraulic oil is small, air does not flow into the filter case 10 through the exhaust hole, and stable driving is possible.

Further, according to the present embodiment, since the bottom surface 44 of the outflow portion 40 covers the opening on the upper side of the filter medium 51, the total length of the filter device 1 in which the reflux filter and the suction filter are integrated can be shortened.

In the present embodiment, the air vent ( holes 31e and 32e) communicates the space S2 with the space S3, but the air vent may not necessarily communicate the space S2 with the space S3. For example, the air vent may communicate a space inside the filter case 10 with a space outside the filter case 10. Even in this case, when the machine tool is stopped, air can be caused to flow into the filter housing 10 through the exhaust hole. However, in order to return the hydraulic oil to the tank 100 when the hydraulic oil passes through the exhaust hole, it is preferable that both ends are opened on the surface of the lower side of the lid body 30, the exhaust hole communicating the space S2 with the space S3.

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

< second embodiment >

Fig. 10 is a sectional view showing an outline of a filter device 2 as an embodiment of the present invention. In fig. 10, hatching indicating a cross section is omitted. The same components 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 (not shown), and a suction filter 50 (not shown).

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

The plate 24A is provided at an upper end of the filter medium 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 main body 32A and the cover 33 removed. The plate 24A has a substantially cylindrical portion 24A adjacent to the inside of 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.

Returning to the description of fig. 10. The cover body 32A is a substantially thick plate-like member provided to cover the hollow portion of the mounting portion 31 from above the mounting portion 31. The lid main body 32A mainly has 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 on the second cylindrical portion 32 c. The rib 32g and the projection 32f are provided on the surface of the lower side of the second cylindrical portion 32c in such a manner as to project downward (-z direction).

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

The projection 32f is inserted into the hole 24c formed on the projection 24 b. In other words, the protrusion 32f and the hole 24c have corresponding shapes. In the present embodiment, the hole 24c is a shape including the characters "Y", "a", "M", "S", "H", "I", "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 projections 32f may also be in the shape representing at least one of a character, a symbol, a pattern, and a mirror image thereof. For example, the hole 24c and the projection 32f may be a company name of a company that manufactures and sells the filter element 20 and the hydraulic actuator incorporating the filter element 20, characters, shapes, and the like of a registered trademark, and mirror images thereof.

Further, the positions and the number of the protrusions 24b, the holes 24c, the protrusions 32f, and the like are not limited thereto. Further, the rib 32g is not essential.

Returning to the description of fig. 10. After replacing the filter element 20A, a new filter element 20A is inserted into the filter case 10, and then the cover 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 along the cylindrical portion 24 a. Further, the protrusions 32f are inserted into the corresponding holes 24c, respectively.

According to the present embodiment, the use of a filter cartridge other than the filter cartridge 20A, which is a standard product, can be prevented.

While the embodiments of the present invention have been described in detail with reference to the drawings, the specific configurations are 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 are described in detail for easy understanding of the present invention, but are not necessarily limited to having all of the described configurations. 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.

The term "substantially" is a concept including not only the case of being strictly identical but also errors and variations to the extent that identity is not lost. For example, the "substantially cylindrical shape" is not limited to a strictly cylindrical shape, but includes a concept that can be regarded as the same as the cylindrical shape, for example. For example, when only orthogonal, parallel, or uniform expression is used, the expression includes not only the case where the components are strictly orthogonal, parallel, or uniform, but also the case where the components are substantially parallel, substantially orthogonal, or substantially uniform.

The term "vicinity" means a region in a range (which can be arbitrarily determined) including the vicinity of a reference position. For example, the term "near the end" means a region in the range near the end, and may or may not include the end.

Description of the symbols

1. 2: a filter device; 10: a filter housing; 11: a first housing; 12: a second housing; 13: an installation part; 13 a: a plate-like portion; 14: a third housing; 14 a: a bottom surface; 14 b: an aperture; 14 c: a through hole; 15: an inner housing; 15a, 15 b: a cylindrical portion; 15: an aperture; 20: a filter element; 21: a filter material; 22: an outer cylinder; 23: an inner barrel; 24. 24A, 25: a plate; 24 a: a cylindrical portion; 24 b: a protrusion portion; 24 c: an aperture; 30: a cover body; 31: an installation part; 31 a: a protrusion; 31 b: an aperture; 31c, 31 e: an aperture; 32. 32A: a cover main body; 32 a: a flange portion; 32 b: a first cylindrical portion; 32c, the ratio of: a second cylindrical portion; 32 d: a plate-like portion; 32e, and (3): an aperture; 32 g: a rib; 32 f: a protrusion portion; 33: a cover; 40: an outflow section; 41. 42: a cylindrical portion; 43: a connecting portion; 43 a: an upper surface; 43 b: a cylindrical portion; 43 c: an outflow port; 43 d: a rib; 43e, 43 g: an aperture; 43 f: a rod-shaped portion; 44: a bottom surface; 44 a: a rib; 44 b: a recess; 50: a suction filter; 51: a filter material; 52: a mounting member; 61: a valve; 62: a differential pressure sensor; 65. 66, 67: a screw; 70: a back pressure valve; 71: a valve body; 71: an aperture; 71 b: a recess; 72: an elastic member; 73: a rod-like member; 81. 82, 83: a sealing member; 100: a tank; 101: an upper surface; 101 a: an opening part; 102: a bottom surface; 102 a: an outflow port; 105: mounting a plate; 105 a: a notch; 106: and an inflow pipe.

Claims (5)

1. A filter device provided in a tank for storing a liquid, the filter device comprising:

a filter case mounted on the tank and having a substantially bottomed cylindrical shape with an open upper end;

a filter element provided in the filter housing and having a substantially cylindrical filter medium;

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

an inflow portion that causes 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 on the outflow portion,

the outflow section has an upper surface and a bottom surface which are provided separately, and a cylindrical section which is provided to protrude upward from the upper surface and is attached to a through hole formed in the filter housing, the cylindrical section and the upper surface being provided with a hole through which the liquid passes,

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 body is movable between a closed position in which the valve body and the upper surface abut and an open position in which the valve body and the upper surface do not abut,

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

an outflow port is formed at a position overlapping the concave portion in a plan view of the upper surface,

in the closed position, a space inside the filter element communicates with a space outside the filter housing through 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 is disposed at an upper side of the can,

both ends of the air vent hole are opened on the surface of the lower side of the lid body, and the space inside the filter element is communicated with the space outside the filter housing and inside the tank.

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

a portion of the filter housing adjacent to the opening portion of the upper end is constricted.

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

a second filter portion having a substantially cylindrical shape,

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

the lower side of the second filter part is provided with a mounting component,

the second filter portion is provided on the tank via the mounting member.

5. The filter device according to any one of claims 1 to 4,

the filter element has an upper plate provided on an end portion of an upper side of the filter material,

a protrusion part protruding downwards is formed on the back of the cover body,

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

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