Filtration device, and tank device

Abstract

To suppress suction of a working oil containing many air bubbles by a hydraulic pump with a simpler method than conventional one.SOLUTION: A first filtration device 11 comprises: a housing 111 which is located in a tank 31 for accumulating a working oil 200; a cylindrical filter medium 112 which is accommodated in the housing 111, and of which a central axis extends in a vertical direction; an inflow part 113 which flows the working oil 200 to be filtered by the filter medium 112 into the housing 111; an outflow part 114 which is located on a ground side in the vertical direction with respect to the inflow part 113, flows the working oil 200 filtered by the filter medium 112 outside the housing 111; an umbrella-shaped or substantially umbrella-shaped guide member 115 which guides the working oil 200 flowed out from the outflow part 114 so as to flow the ground side to top side in the vertical direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a filtration device and a tank device. [Background technology]

[0002] A hydraulic circuit that circulates hydraulic oil related to the operation of hydraulic devices such as construction machinery is equipped with a filter to keep the hydraulic oil clean. For example, a hydraulic oil tank provided in the hydraulic circuit that stores the hydraulic oil contains a return filter that manages the cleanliness of the entire hydraulic circuit by filtering the hydraulic oil that circulates through the hydraulic circuit and returns to the hydraulic oil tank, and a suction filter that filters the hydraulic oil that has been filtered by the return filter and flowed into the hydraulic oil tank and then flows out of the hydraulic oil tank. The hydraulic oil that has been filtered by the suction filter and flowed out of the hydraulic oil tank is sucked into a hydraulic pump and circulates again within the hydraulic circuit. Hydraulic oil circulating through a hydraulic circuit and returning to the hydraulic oil tank may contain air bubbles (aeration). If hydraulic oil containing a large number of air bubbles is drawn into a hydraulic pump, the pressure may drop when the hydraulic oil is discharged from the hydraulic pump. For this reason, Patent Document 1 proposes a technology in which the flow of hydraulic oil filtered by a return filter is changed into a swirling flow, and the air bubbles contained in the hydraulic oil are collected in the center of the swirling flow and flow upward inside the hydraulic oil tank. In this technology, hydraulic oil is caused to collide with a swirl flow-forming member having a left blade portion inclined downward toward the rear and a right blade portion inclined downward toward the front, changing the flow of hydraulic oil into a swirling flow, and air bubbles contained in the hydraulic oil are collected in the center of the swirling flow. The air bubbles collected in the center of the swirling flow then flow upward inside the hydraulic oil tank through a pipe-shaped air bubble channel member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-45923 Summary of the Invention [Problem to be solved by the invention]

[0004] However, changing the flow of hydraulic oil filtered by the return filter into a swirling flow and flowing it upward inside the hydraulic oil tank requires the installation of a large-scale device like the one described above inside the hydraulic oil tank, which increases costs. For this reason, there has been a need for a simpler method to develop technology that can prevent hydraulic oil containing a large number of air bubbles from being sucked into the pump. An object of the present invention is to prevent hydraulic oil containing a large number of bubbles from being sucked into a pump using a method that is simpler than conventional methods. [Means for solving the problem]

[0005] The filtering device of the present invention, which was completed with this purpose in mind, is characterized by comprising a housing placed inside a tank that stores hydraulic oil, a cylindrical filter material contained in the housing and with a central axis extending in the vertical direction of the tank, an inlet portion that allows the hydraulic oil filtered by the filter material to flow into the inside of the housing, an outlet portion that is placed on the ground side of the inlet portion in the vertical direction and allows the hydraulic oil filtered by the filter material to flow outside the housing, and an umbrella-shaped or approximately umbrella-shaped guide member that guides the hydraulic oil that flows out of the outlet portion so that it flows from the ground side to the top side in the vertical direction. Here, the guide member may be characterized by having a first restraining wall that prevents the hydraulic oil that has flowed out from the outflow portion from moving toward the earth in the vertical direction, and a second restraining wall that is continuous with the first restraining wall and prevents the hydraulic oil from moving radially outward of the filter material. The second restricting wall may also be characterized in that an end portion on the top side in the vertical direction of the second restricting wall is positioned radially outward of an end portion on the bottom side in the vertical direction of the second restricting wall. The second restricting wall may have a radial distance from the central axis of the top end in the vertical direction that is not constant. The outflow portion may also be characterized as being a cylindrical member arranged approximately coaxially with the central axis of the filter material and having an outflow port formed therein that allows the hydraulic oil to pass through and flow out to the outside. The outlet may be a group of through holes formed in at least a part of the cylindrical member and passing through the cylindrical member in the radial direction. The group of through holes may be formed on a circumferential surface having a central angle of 180 degrees or less about the central axis of the cylindrical member. The group of through holes may be formed on the circumferential surface of the cylindrical member on the ground side in the vertical direction. In addition, the tank device of the present invention comprises a tank for storing hydraulic oil, a first filtering device arranged on the top side of the tank in the vertical direction and filtering the hydraulic oil flowing into the tank, and a second filtering device arranged on the bottom side of the tank in the vertical direction and further filtering the hydraulic oil stored in the tank and discharging it to the outside of the tank, wherein the first filtering device has a housing immersed in the hydraulic oil, a cylindrical filter material housed in the housing and having a central axis extending in the vertical direction, an inlet portion for allowing the hydraulic oil to flow into the housing, an outlet portion arranged on the bottom side of the inlet portion in the vertical direction and discharging the hydraulic oil filtered by the filter material to the outside, and an umbrella-shaped or approximately umbrella-shaped guide member for guiding the hydraulic oil flowing out of the outlet portion so that it flows from the bottom side to the top side in the vertical direction. Here, the outflow section may be a cylindrical member arranged approximately coaxially with the central axis of the filter material and having an outflow port formed therein for passing the hydraulic oil and discharging it to the outside, and the outflow port may be a group of through holes formed on the circumferential surface of the cylindrical member that does not face the second filtering device and that penetrate the cylindrical member in the radial direction. [Effects of the Invention]

[0006] According to the filtering device of the present invention, an umbrella-shaped or approximately umbrella-shaped guide member guides the hydraulic oil flowing out of the outlet so that it flows from the bottom side to the top side of the tank in the vertical direction, thereby making it possible to prevent hydraulic oil containing a large amount of air bubbles from being sucked into the pump using a simpler method than conventional methods. According to the tank device of the present invention, the umbrella-shaped or approximately umbrella-shaped guide member that constitutes the first filtering device arranged in the tank guides the hydraulic oil that flows out from the outlet of the first filtering device so that it flows from the bottom side to the top side in the vertical direction of the tank, thereby making it possible to prevent hydraulic oil containing a large amount of air bubbles from being sucked into the pump using a method that is simpler than conventional methods. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing an example of the configuration of a hydraulic circuit including a tank device according to an embodiment of the present invention; [Figure 2] 1(A) and 1(B) are diagrams showing an example of the configuration of a first filtering device according to the present embodiment. [Figure 3] 3 is a diagram showing the movement of the hydraulic oil that has flowed out into the tank from the first filtration device shown in FIGS. 2(A) and 2(B) by the directions of arrows. FIG. [Figure 4] FIG. 10 is a diagram showing an example in which the first filtering device does not include a guide member as a component. [Figure 5] 10(A) to 10(D) are diagrams showing modified examples of the outflow section and guide member of the first filtering device of FIG. 3 according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. <Hydraulic circuit configuration> 1 is a diagram showing an example of the configuration of a hydraulic circuit 1 including a tank device 10 according to this embodiment. In the following, the top-bottom direction refers to the direction connecting the top and bottom surfaces of a tank 31 that constitutes the tank device 10. Hereinafter, the top side in the direction connecting the top and bottom surfaces of the tank 31 will be referred to as the "top side in the top-bottom direction," and the bottom side in the direction connecting the top and bottom surfaces of the tank 31 will be referred to as the "bottom side in the top-bottom direction."

[0009] The hydraulic circuit 1 is a hydraulic circuit that circulates hydraulic oil 200 involved in the operation of a hydraulic device such as a construction machine. The hydraulic circuit 1 includes a tank device 10 that temporarily stores the hydraulic oil 200 circulating within the hydraulic circuit 1 to keep it clean, a pump 41 such as a hydraulic pump that circulates the hydraulic oil 200 within the hydraulic circuit 1 by sucking in and discharging the hydraulic oil 200 that has flowed out of the tank device 10, and a working hydraulic circuit 51 that is used to operate the hydraulic device. The working hydraulic circuit 51 includes, for example, a hydraulic circuit for hydraulic cylinders that is used when the construction machine is operating, a traveling hydraulic circuit that is used when the construction machine is moving, and a swing hydraulic circuit that is used when the construction machine is swinging.

[0010] (Tank equipment) The tank device 10 includes a tank 31 that stores hydraulic oil 200, and a first filtering device 11 and a second filtering device 21 that are disposed inside the tank 31. The tank 31 stores an amount of hydraulic oil 200 indicated by an oil level 201. The upper side of the oil level 201 in the vertical direction is filled with air.

[0011] The first filtering device 11 is a filtering device that is disposed on the top side of the tank 31 in the vertical direction and filters the hydraulic oil 200 that flows into the tank 31. Here, "disposed on the top side of the tank 31 in the vertical direction" means that at least a part of the first filtering device 11 is disposed in an area that exceeds approximately two-thirds of the height of the tank 31 in the vertical direction. The first filtering device 11 is also called a return filter. The specific configuration of the first filtering device 11 will be described later.

[0012] The second filtering device 21 is disposed on the bottom side of the interior of the tank 31, and is a filtering device that further filters the hydraulic oil 200 stored in the tank 31 and discharges it to the outside of the tank 31. Here, "disposed on the bottom side of the interior of the tank 31" means that at least a portion of the second filtering device 21 is disposed in an area not exceeding about one-third of the height of the tank 31 in the top-to-bottom direction. The second filtering device 21 is also called a suction filter or a suction strainer.

[0013] (1st filtration device) 2(A) and 2(B) are diagrams showing an example of the configuration of the first filtering device 11 according to this embodiment. FIG. 3 is a diagram showing, by the directions of arrows, how the hydraulic oil 200 that has flowed out from the first filtering device 11 shown in FIGS. 2(A) and 2(B) into the tank 31 moves. As shown in FIG. 2(A), the first filtering device 11 includes a housing 111 disposed inside the tank 31 that stores the amount of hydraulic oil 200 indicated by the oil level 201, and a cylindrical filter material 112 housed in the housing 111 and having a central axis extending in the vertical direction of the tank 31. The filter material 112 filters the hydraulic oil 200 by causing it to flow from the outside to the inside in the radial direction. However, the filter material 112 may also filter the hydraulic oil by causing it to flow from the inside to the outside in the radial direction. The first filtering device 11 also includes an inlet portion 113 that allows the hydraulic oil 200 filtered by the filter material 112 to flow into the housing 111.

[0014] 2(A) and 2(B), the first filtering device 11 includes an outlet 114, which is disposed closer to the bottom than the inlet 113 and allows the hydraulic oil 200 filtered by the filter medium 112 to flow out of the housing 111. The outlet 114 is a cylindrical member disposed approximately coaxially with the central axis of the filter medium 112 and has outlets 141 formed therein, which allow the hydraulic oil 200 to pass through and flow out to the outside. Here, "approximately coaxial" does not necessarily mean completely coaxial, but rather includes, for example, an offset of approximately 10 cm or less. The outlets 141 are a group of through-holes that radially penetrate the cylindrical outlet 114.

[0015] The first filtering device 11 also includes an umbrella-shaped or approximately umbrella-shaped guide member 115 that guides the hydraulic oil 200 that has flowed out from the outflow portion 114 to flow from the bottom side to the top side in the vertical direction. The guide member 115 has a first suppression wall 151 that suppresses the hydraulic oil 200 that has flowed out from the outflow portion 114 to the bottom side in the vertical direction, and a second suppression wall 152 that suppresses the hydraulic oil 200 that has flowed out from the outflow portion 114 to the outside from moving radially outward of the first filtering device 11.

[0016] The second restraint wall 152 is erected so as to be continuous with the first restraint wall 151. In the guide member 115, an end 153 on the top side of the second restraint wall 152 in the vertical direction is positioned radially outward from an end 153 on the bottom side of the second restraint wall 152, which is opposite the end 153. Therefore, the guide member 115 as a whole has an umbrella or approximately umbrella shape. Note that the "end 153 on the bottom side of the second restraint wall 152 in the vertical direction" refers to the radially outer end of the second restraint wall 152, i.e., the connecting portion between the first restraint wall 151 and the second restraint wall 152.

[0017] Since guide member 115 has an umbrella or approximately umbrella shape as a whole, at least a part of hydraulic oil 200 that flows out from outflow portion 114 collides with guide member 115. This causes a flow toward the top side of guide member 115 in the vertical direction and toward the outside in the radial direction, that is, as shown in Fig. 3, a flow of hydraulic oil 200 in the direction of thick arrow 301 is created, and flows in the directions of thick arrows 302 to 304 are also created.

[0018] Specifically, the flow indicated by thick arrow 302 is a flow rising upward toward the oil surface 201, and the flow indicated by thick arrow 303 is a flow parallel (horizontal) to the oil surface 201 toward the inner wall surface of the tank 31. The flow indicated by thick arrow 304 is a flow descending downward toward the bottom surface of the tank 31. When the hydraulic oil 200 stored in the tank 31 flows in the directions indicated by thick arrows 301 to 304 in FIG. 3, most of the air bubbles contained in the hydraulic oil 200 that flowed out of the first filtration device 11 into the tank 31 pass through the oil surface 201 and become part of the air filling the upper side of the tank 31, disappearing from the hydraulic oil 200. Consequently, the hydraulic oil 200 that does not contain many air bubbles flows into the second filtration device 21. As a result, the hydraulic oil 200 containing many air bubbles is prevented from being drawn into the pump 41 (see FIG. 1).

[0019] <When no guide member is provided> Figure 4 is a diagram showing an example in which the first filtering device does not include the guide member 115 as a component. Unlike the first filtering device 11 in Figure 3 described above, the first filtering device shown in Figure 4 does not include the guide member 115 as a component. Therefore, the way in which the hydraulic oil that has flowed out of the first filtering device into the tank moves is significantly different from that shown in Figure 3. The thin arrows in Figure 4 indicate the direction in which the hydraulic oil moves.

[0020] The first filtering device shown in Fig. 4 is a filtering device disposed inside a tank that stores hydraulic oil at a level indicated by the oil level. The first filtering device includes an outlet portion that allows hydraulic oil filtered by a filter material (not shown) to flow out of the housing. The outlet portion is a cylindrical member formed with an outlet port that allows hydraulic oil to pass through and flow out to the outside, similar to the outlet portion 114 in Fig. 3. The outlet port is a group of through holes that radially penetrate the outlet portion, which is a cylindrical member.

[0021] The first filtering device shown in Fig. 4 does not have the guide member 115 shown in Fig. 3, and therefore the hydraulic oil flowing out from the outflow port does not flow as indicated by the thick arrows 301 to 304 in Fig. 3. Therefore, unlike the present embodiment shown in Fig. 3, it is difficult to eliminate air bubbles contained in the hydraulic oil that has flowed out from the first filtering device into the tank. As a result, the hydraulic oil containing many air bubbles flows into the second filtering device 21, and it is not possible to prevent the hydraulic oil containing many air bubbles from being sucked into a pump (not shown).

[0022] <Modification> 5A to 5D are diagrams showing modified examples of the outflow section 114 and the guide member 115 of the first filtration device 11 of FIG. 3 according to this embodiment.

[0023] (Variation 1) The outflow section 114 shown in Fig. 5(A) has the same configuration as the outflow section 114 of the first filtering device 11 in Fig. 3 described above, and therefore a description thereof will be omitted. The guide member 125 shown in Fig. 5(A) has a first suppression wall 251 that suppresses the hydraulic oil 200 that has flowed out from the outflow section 114 from moving toward the bottom in the vertical direction of the tank 31 (see Fig. 1), and a second suppression wall 252 that is continuous with the first suppression wall 251 and suppresses the hydraulic oil 200 from moving radially outward from the outflow section 114.

[0024] 3 described above, the guide member 125 shown in FIG. 5(A) is different from the guide member 115 of the first filtration device 11 in FIG. 3 in that the radial distance from the central axis of the top end 253 of the second restriction wall 252 in the vertical direction (the central axis of the outflow section 114) is not constant. That is, in the guide member 125 shown in FIG. 5(A), the radial distance from the central axis of the top end 253 of the second restriction wall 252 in the vertical direction (the central axis of the outflow section 114) is not constant, and may be either distance r1 or distance r2, which is shorter than distance r1. Therefore, the length of the second restriction wall 252 in the vertical direction is not constant either.

[0025] With the guide member 125 having such a configuration, for example, the radial distance (e.g., distance r1) from the central axis of the top end 253 of the second suppression wall 252 disposed opposite the second filtering device 21 (see FIG. 1 ) can be made longer than the radial distance (e.g., distance r2) from the central axis of the top end 253 of the second suppression wall 252 disposed opposite the second filtering device 21. In this case, by disposing the second suppression wall 252 opposite the second filtering device 21, the second suppression wall 252 becomes a large wall that blocks the flow of the hydraulic oil 200 flowing out of the outflow portion 114 toward the second filtering device 21. As a result, the risk of hydraulic oil 200 containing a large amount of air bubbles flowing into the second filtering device 21 can be reduced.

[0026] (Variation 2) The guide member 115 shown in Fig. 5(B) has the same configuration as the guide member 115 of the first filtering device 11 in Fig. 3 described above, and therefore a description thereof will be omitted. The outflow section 124 shown in Fig. 5(B) has a configuration basically similar to that of the outflow section 114 in Fig. 5(A) described above, and is a cylindrical member having an outflow port 141 formed therein, which is a group of through-holes that allow the hydraulic oil 200 to pass through and flow out to the outside. However, unlike the outflow port 141 of the outflow section 114 in Fig. 5(A), the outflow port 141 of the outflow section 124 shown in Fig. 5(B) has a group of through-holes serving as the outflow port 141 formed on a circumferential surface having a central angle of 180 degrees or less about the central axis of the cylindrical member.

[0027] With the outflow section 124 having such a configuration, for example, the outlet 141 can be formed on a surface of the circumferential surface of the outflow section 124 that does not face the second filtering device 21 (see FIG. 1), and the outlet 141 can be prevented from being formed on a surface facing the second filtering device 21. In this case, the hydraulic oil 200 that flows out from the outlet 141 formed on the surface of the circumferential surface of the outflow section 124 that faces the second filtering device 21 does not flow directly toward the second filtering device 21, thereby reducing the risk that the hydraulic oil 200 containing a large number of bubbles will flow into the second filtering device 21.

[0028] (Variation 3) The guide member 115 shown in Fig. 5(C) has the same configuration as the guide member 115 of the first filtration device 11 in Fig. 3 described above, and therefore a description thereof will be omitted. The outflow section 134 shown in Fig. 5(C) has a configuration basically similar to the outflow section 114 in Fig. 5(A) described above, and is a cylindrical member having an outlet 141, which is a group of through holes that allow the hydraulic oil 200 to pass through and flow out to the outside. However, the outflow section 134 shown in Fig. 5(C) is longer in the vertical direction than the outflow section 114 in Fig. 5(A). Furthermore, in the outflow section 134, the outlet 141, which is a group of through holes, is formed on the circumferential surface on the bottom side in the vertical direction of the cylindrical member, but no outlet 141 is formed on the circumferential surface on the top side in the vertical direction.

[0029] According to the outflow section 134 having such a configuration, the outlets 141 can be formed in a concentrated manner on the circumferential surface on the bottom side of the outflow section 134. In this case, the hydraulic oil 200 flows out from the outlets 141 formed at positions on the circumferential surface of the outflow section 134 that are close to the guide member 115, and therefore the hydraulic oil 200 that flows out from the outlets 141 is easily guided by the guide member 115. As a result, the hydraulic oil 200 that contains a large amount of air bubbles is prevented from being sucked into the pump 41 (see FIG. 1).

[0030] Although not shown, the outflow section 134 may have an outlet 141 formed only on the circumferential surface on the top side in the vertical direction, and no outlet 141 formed on the circumferential surface on the bottom side. However, in order for the guide member 115 to function effectively, it is preferable that the hydraulic oil 200 flowing out from the outlet 141 be easily guided to the guide member 115. For this reason, it is preferable that the outlet 141 and the guide member 115 are located close to each other, and therefore the configuration shown in FIG. 5(C) is more preferable than a configuration in which the outlet 141 is formed only on the circumferential surface on the top side in the vertical direction of the outflow section 134, and no outlet 141 is formed on the circumferential surface on the bottom side.

[0031] (Variation 4) The guide member 115 shown in Fig. 5(D) has the same configuration as the guide member 115 of the first filtering device 11 in Fig. 3 described above, and therefore a description thereof will be omitted. The outflow section 144 shown in Fig. 5(D) is a cylindrical member having an opening 142 formed on the bottom side in the vertical direction, which allows the hydraulic oil 200 to pass through and flow out to the outside. The outflow section 144 shown in Fig. 5(D) is longer in the vertical direction than the outflow section 114 in Fig. 5(A) and the outflow section 124 in Fig. 5(B).

[0032] 5(A) to 5(C) is not formed in the outflow portion 134 having such a configuration, but the hydraulic oil 200 flowing out from the opening 142 can be guided by the guide member 115 as described above. This prevents the hydraulic oil 200 containing a large amount of bubbles from being sucked into the pump 41.

[0033] In summary, the first filtering device 11 of the present invention only needs to have the following configuration, and can take on a variety of different embodiments. That is, the first filtration device 11 is a filtration device characterized by comprising: a housing 111 arranged inside a tank 31 that stores hydraulic oil 200; a cylindrical filter material 112 that is contained in the housing 111 and has a central axis extending in the vertical direction; an inlet section 113 that allows the hydraulic oil 200 filtered by the filter material 112 to flow into the inside of the housing 111; an outlet section 114 that is arranged on the bottom side of the inlet section 113 in the vertical direction and allows the hydraulic oil 200 filtered by the filter material 112 to flow out of the housing 111; and an umbrella-shaped or approximately umbrella-shaped guide member 115 that guides the hydraulic oil 200 that flows out of the outlet section 114 so that it flows from the bottom side to the top side in the vertical direction.

[0034] As a result, the umbrella-shaped or approximately umbrella-shaped guide member 115 guides the hydraulic oil 200 flowing out from the outlet 114 of the first filtering device 11 to flow from the bottom side to the top side in the vertical direction of the tank 31, so that most of the air bubbles contained in the hydraulic oil 200 flowing out from the first filtering device 11 into the tank 31 become part of the air filling the top side in the vertical direction of the oil surface 201 and disappear from the hydraulic oil 200. Then, hydraulic oil 200 that does not contain many air bubbles flows into the second filtering device 21. As a result, it is possible to prevent hydraulic oil 200 containing a large number of air bubbles from being sucked into the pump 41 using a method that is simpler than conventional methods. Furthermore, there is no need to provide a partition plate to control the flow of the hydraulic oil 200 in the tank 31.

[0035] Here, the guide member 115 may be characterized by having a first restraining wall 151 that restrains the hydraulic oil 200 that has flowed out from the outflow section 114 to the outside from moving toward the bottom in the vertical direction of the tank 31, and a second restraining wall 152 that is continuous with the first restraining wall 151 and restrains the hydraulic oil 200 that has flowed out from the outflow section 114 to the outside from moving radially outward of the filter material 112. As a result, the first suppression wall 151 suppresses the hydraulic oil 200 that has flowed out from the outflow portion 114 from moving toward the bottom in the vertical direction of the tank 31, and the second suppression wall 152 suppresses the hydraulic oil 200 that has flowed out from the outflow portion 114 from moving radially outward of the filter medium 112. As a result, the hydraulic oil 200 that has flowed out from the outlet 141 does not flow directly toward the second filtering device 21, thereby reducing the risk that the hydraulic oil 200 containing a large amount of air bubbles will flow into the second filtering device 21.

[0036] Furthermore, the end 153 on the top side in the vertical direction of the second restraining wall 152 may be located radially outward of the end 153 on the bottom side in the vertical direction of the second restraining wall 152. As a result, the first suppression wall 151 suppresses the hydraulic oil 200 that has flowed out from the outflow portion 114 from moving toward the bottom side in the vertical direction of the tank 31, and the second suppression wall 152 suppresses the hydraulic oil 200 that has flowed out from the outflow portion 114 from moving toward the outside in the radial direction of the filter medium 112. As a result, at least a portion of the hydraulic oil 200 that has flowed out from the outflow portion 114 collides with the guide member 115, and a flow is created that flows toward the top side of the guide member 115 in the vertical direction and toward the outside in the radial direction.

[0037] Furthermore, the distance in the radial direction from the central axis of the top end 253 of the second restraining wall 252 in the vertical direction may not be constant. Thus, by disposing the second suppression wall 252 at a position facing the second filtering device 21 (see FIG. 1), the second suppression wall 252 becomes a large wall that blocks the flow of the hydraulic oil 200 that has flowed out from the outflow portion 114 toward the second filtering device 21. As a result, the risk that the hydraulic oil 200 containing a large number of bubbles will flow into the second filtering device 21 can be reduced.

[0038] The outflow section 114 may also be characterized as being a cylindrical member arranged approximately coaxially with the central axis of the filter material 112, and having an outflow port 141 formed therein, through which the hydraulic oil 200 passes and is discharged to the outside. The outlet 141 may also be a group of through holes formed in at least a part of the cylindrical member and passing through the cylindrical member in the radial direction. As a result, hydraulic oil 200 flows out from outlet 141, which is a group of through holes that radially penetrate outflow portion 114, which is a cylindrical member, thereby suppressing pulsation and fluctuations in flow rate when hydraulic oil 200 flows out. As a result, sudden changes in the movement of hydraulic oil 200 flowing inside tank 31 are suppressed.

[0039] Furthermore, the outlet 141, which is a group of through holes, may be formed on a circumferential surface having a central angle of 180 degrees or less about the central axis of the outlet portion 124 (see FIG. 5(B)), which is a cylindrical member. As a result, the hydraulic oil 200 flowing out from the outlet 141 formed on the surface of the circumferential surface of the outflow section 124 facing the second filtering device 21 does not flow directly toward the second filtering device 21, thereby reducing the risk of hydraulic oil 200 containing a large number of bubbles flowing into the second filtering device 21.

[0040] Furthermore, the outlet 141, which is a group of through holes, may be formed on the circumferential surface on the ground side in the vertical direction of the outlet portion 134 (see FIG. 5(C)), which is a cylindrical member. This allows the outflow ports 141 to be formed in a concentrated manner on the circumferential surface on the bottom side of the outflow section 134. In this case, the hydraulic oil 200 flows out from the outflow ports 141 formed at positions on the circumferential surface of the outflow section 134 that are close to the guide member 115, and therefore the hydraulic oil 200 that flows out from the outflow ports 141 is easily guided by the guide member 115. As a result, the hydraulic oil 200 that contains a large amount of air bubbles is prevented from being sucked into the pump 41 (see FIG. 1).

[0041] Furthermore, the tank device 10 of the present invention only needs to have the following configuration, and can take on a variety of different embodiments. That is, the tank device 10 includes a tank 31 for storing hydraulic oil 200, a first filtering device 11 that is arranged on the top side of the tank 31 in the vertical direction and filters the hydraulic oil 200 flowing into the tank 31, and a second filtering device 21 that is arranged on the bottom side of the tank 31 in the vertical direction and further filters the hydraulic oil 200 stored in the tank 31 and causes it to flow out of the tank 31. The first filtering device 11 is arranged in a housing 111 that is immersed in the hydraulic oil 200, and a second filtering device 21 that is housed in the housing 111 and has a central axis This tank device is characterized by having a cylindrical filter material 112 extending in the vertical direction of the tank 31, an inlet section 113 that allows hydraulic oil 200 to flow into the inside of the housing 111, an outlet section 114 that is positioned closer to the bottom in the vertical direction of the tank 31 than the inlet section 113 and allows the hydraulic oil 200 filtered by the filter material 112 to flow to the outside, and an umbrella-shaped or approximately umbrella-shaped guide member 115 that guides the hydraulic oil 200 that flows out of the outlet section 114 so that it flows from the bottom side to the top side in the vertical direction of the tank 31.

[0042] As a result, the umbrella-shaped or approximately umbrella-shaped guide member 115 constituting the first filtering device 11 disposed in the tank 31 guides the hydraulic oil 200 flowing out from the outlet 114 of the first filtering device 11 to flow from the bottom side to the top side in the vertical direction of the tank 31, so that most of the air bubbles contained in the hydraulic oil 200 flowing out from the first filtering device 11 into the tank 31 become part of the air filling the top side in the vertical direction of the oil surface 201 and disappear from the hydraulic oil 200. Then, the hydraulic oil 200 that does not contain many air bubbles flows into the second filtering device 21. As a result, it is possible to prevent hydraulic oil 200 containing a large number of air bubbles from being sucked into the pump 41 using a method that is simpler than conventional methods.

[0043] In addition, the outflow section 124 may be a cylindrical member arranged approximately coaxially with the central axis of the filter material 112, and formed with an outflow port 141 that allows the hydraulic oil 200 to pass through and flow out to the outside, and the outflow port 141 may be characterized as a group of through holes that penetrate the outflow section 124 in the radial direction, and are formed on the surface of the circumferential surface of the cylindrical member, the outflow section 124, that does not face the second filtration device 21. As a result, the hydraulic oil 200 flowing out from the outlet 141 formed on the surface of the circumferential surface of the outflow section 124 facing the second filtering device 21 does not flow directly toward the second filtering device 21, thereby reducing the risk of hydraulic oil 200 containing a large number of bubbles flowing into the second filtering device 21.

[0044] <Other embodiments> Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. Furthermore, the effects of the present invention are not limited to those described in the above-described embodiments. For example, the configuration of the hydraulic circuit 1 shown in FIG. 1, the configuration of the first filtration device 11 shown in FIG. 2, and the configurations of the outflow section and guide member shown in FIGS. 5(A) to 5(D) are merely examples for achieving the object of the present invention, and are not particularly limited. [Explanation of symbols]

[0045] 1...hydraulic circuit, 10...tank device, 11...first filtration device, 21...second filtration device, 31...tank, 41...pump, 51...working hydraulic circuit, 111...housing, 112...filtering material, 113...inlet portion, 114, 124, 134, 144...outlet portion, 115, 125...guiding member, 141...outlet port, 142...opening, 151, 251...first restraining wall, 152, 252...second restraining wall, 153, 253...end, 200...hydraulic oil, 201...oil level

Claims

1. a housing disposed inside a tank that stores hydraulic oil; A cylindrical filter medium accommodated in the housing and having a central axis extending in the vertical direction of the tank; an inlet portion that allows the hydraulic oil filtered by the filter material to flow into the housing; An outlet portion that is arranged on the ground side of the inlet portion in the vertical direction and that allows the hydraulic oil filtered by the filter material to flow out of the housing; an umbrella-shaped or substantially umbrella-shaped guide member that guides the hydraulic oil flowing out from the outflow portion so that the hydraulic oil flows from the bottom side to the top side in the vertical direction; A filtration device comprising:

2. The guide member has a first restraining wall that restrains the hydraulic oil that has flowed out from the outflow portion from moving toward the ground in the vertical direction, and a second restraining wall that is continuous with the first restraining wall and restrains the hydraulic oil from moving radially outward of the filter material. The filtration device of claim 1 .

3. an end portion of the second restraining wall on the top side in the top-bottom direction is located radially outward of an end portion of the second restraining wall on the bottom side in the top-bottom direction, The filtration device of claim 2 .

4. The radial distance from the central axis of the top end of the second restraining wall in the top-bottom direction is not constant. The filtration device of claim 2 .

5. The outflow portion is a cylindrical member arranged approximately coaxially with the central axis of the filter material, and has an outflow port formed therein through which the hydraulic oil passes and flows out to the outside. The filtration device of claim 1 .

6. The outlet is a group of through holes formed in at least a part of the cylindrical member and penetrating the cylindrical member in a radial direction.

6. The filtration device of claim 5.

7. The group of through holes is formed on a circumferential surface of a circle having a central angle of 180 degrees or less about the central axis of the cylindrical member.

7. The filtration device of claim 6.

8. The group of through holes is formed on the circumferential surface of the cylindrical member on the ground side in the top-bottom direction.

7. The filtration device of claim 6.

9. The hydraulic oil supply system comprises a tank for storing hydraulic oil, a first filtering device disposed on the top side of the tank and filtering the hydraulic oil flowing into the tank, and a second filtering device disposed on the bottom side of the tank and filtering the hydraulic oil stored in the tank further and discharging the filtered hydraulic oil to the outside of the tank, The first filtration device is a housing immersed in the hydraulic oil; A cylindrical filter material housed in the housing and having a central axis extending in the vertical direction; an inlet portion that allows the hydraulic oil to flow into the housing; An outflow portion that is arranged on the ground side in the vertical direction relative to the inflow portion and that causes the hydraulic oil filtered by the filter material to flow out to the outside; an umbrella-shaped or substantially umbrella-shaped guide member that guides the hydraulic oil flowing out from the outflow portion so that the hydraulic oil flows from the bottom side to the top side in the vertical direction; A tank device comprising:

10. The outflow portion is a cylindrical member arranged approximately coaxially with the central axis of the filter medium, and has an outflow port formed therein through which the hydraulic oil passes and flows out to the outside. The outlet is a group of through holes formed on a surface of the circumferential surface of the cylindrical member that does not face the second filtration device and that penetrates the cylindrical member in a radial direction.

10. The tank arrangement of claim 9.

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