Air bubble removal device

Abstract

To provide an air bubble removal device that can separate and remove air bubbles included in a lubricant or the like, which can prevent occurrence or the like abnormal noise due to air biting in a hydraulic pump.SOLUTION: The air bubble removal device is configured to comprise: a casing member 10 which has an inner flow passage space 14 constituting an inner flow passage of suction-side piping 101 and an air bubble storage space 15, formed at an upper part of the inner flow passage space 14, which stores air bubbles emerging from mission oil; piping 104a and 104b for ejecting air bubbles whose one ends are connected to the casing member 10 and which have air bubble ejection passages communicating with the air bubble storage space 15; and vacuum pumps 140a and 140b, connected to the other ends of the piping 104a and 104b for ejecting air bubbles, which suction and eject air bubbles in the air bubble storage space 15.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bubble removal device that removes bubbles from a liquid flowing through an internal flow path of a pipe. [Background technology]

[0002] Lubricating oils used in various machines and hydraulic oils flowing through hydraulic circuits in industrial hydraulic equipment can become contaminated with foreign matter such as metal dust and debris during operation of the machines or industrial hydraulic equipment. In such cases, the machines or industrial hydraulic equipment may be damaged by the contaminated foreign matter. Therefore, to remove the contaminated foreign matter, filter devices are installed in the piping of lubrication circuits or hydraulic circuits to filter the lubricating oil, hydraulic oil, etc. One such filter device, as disclosed in Patent Document 1, for example, includes a filter case having an inlet and an outlet, and a filter element (filter material) installed within the filter case. As a result, when the lubricating oil, hydraulic oil, etc. passes through the filter device, the foreign matter can be captured and removed from the filter material surface and filter layer of the filter element installed within the filter case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-188430 A Summary of the Invention [Problem to be solved by the invention]

[0004] In agricultural machinery, construction machinery, and the like, many air bubbles can be generated in the lubricating oil or hydraulic oil due to air entrapment by the transmission gears during the lubrication process of the transmission, vibrations that occur during operation, and other factors. When many such air bubbles flow into the filter device along with the lubricating oil, they can accumulate in certain locations within the filter case, causing air pockets, or as they pass through the filter element, the bubbles can grow larger due to the influence of the internal structure of the filter material, etc. When lubricating oil containing large air bubbles flows out of the filter device and is supplied to a hydraulic pump, abnormal noise occurs in the hydraulic pump due to air entrapment, and air bubbles in the lubricating oil can cause problems such as reduced hydraulic power and poor lubrication.

[0005] The present invention has been made in consideration of these problems, and aims to provide an air bubble removal device that can separate and remove air bubbles contained in lubricating oil, hydraulic oil, etc., thereby preventing the generation of abnormal noise due to air entrapment in hydraulic pumps. [Means for solving the problem]

[0006] In order to achieve the above object, the bubble removal device according to the present invention is a liquid supply system in which liquid in a tank (e.g., an oil pan 130 in the embodiments) is sucked by a liquid pump (e.g., a first hydraulic pump 110 and a second hydraulic pump 120 in the embodiments) and supplied to a supply target (e.g., a hydrostatic continuously variable transmission 112 and an auxiliary transmission 121 in the embodiments), the bubble removal device being provided midway through a suction side pipe (e.g., a suction side pipe 101 in the embodiments) connecting the tank and the liquid pump, and removing bubbles in liquid flowing through an internal flow path of the suction side pipe, The flow passage extends from an inlet opening through which the liquid flows to an outlet opening through which the liquid that has flowed into the inlet opening flows, and forms a flow of the liquid from the inlet opening to the outlet opening.The liquid supply system includes a casing member (e.g., casing member 10 in the embodiments) having a casing internal flow path space (e.g., internal flow path space 14 in the embodiments) and a bubble storage space (e.g., bubble storage space 15 in the embodiments) formed above the casing internal flow path space for storing bubbles that rise to the surface from the liquid flowing through the casing internal flow path space; a bubble discharge pipe (e.g., bubble discharge pipes 104a, 104b in the embodiments) having one end connected to the casing member and a bubble discharge flow path communicating with the bubble storage space; and a bubble suction device (e.g., vacuum pumps 140a, 140b in the embodiments) connected to the other end of the bubble discharge pipe for sucking and discharging bubbles in the bubble storage space via the bubble discharge flow path.

[0007] In the bubble removal device having the above configuration, it is preferable that the cross-sectional area perpendicular to the liquid flow direction of the casing internal flow path space is larger than the cross-sectional area perpendicular to the liquid flow direction of the internal flow path of the suction side piping (for example, the inlet flow path 57 in the embodiment).

[0008] In the bubble removal device having the above configuration, the liquid supply system preferably includes a filter device (e.g., filter device 30 in the embodiments) that filters the liquid flowing through the internal flow path of the suction side piping, and the filter device is a cartridge-type filter device having a filter side connecting portion (e.g., protrusion 36, female thread 36a in the embodiments) that can be detachably connected to a piping side connecting portion (e.g., cartridge connecting portion 50 in the embodiments) provided on the suction side piping, and the casing member preferably includes an inlet side connecting portion (e.g., base end portion of secondary side flow path member 16, female thread 16b in the embodiments) that can be connected to the piping side connecting portion, and an outlet side connecting portion (e.g., base end portion of secondary side flow path member 16, male thread 16a in the embodiments) that can be connected to the filter side connecting portion.

[0009] In the bubble removal device having the above configuration, it is preferable that the position of the inlet (e.g., inlet 72 in the embodiment) through which the liquid flows into the casing internal flow path space and the position of the outlet (e.g., outlet 73 in the embodiment) through which the liquid flows out of the casing internal flow path space are offset in a direction perpendicular to the flow direction of the liquid in the casing internal flow path space.

[0010] In the bubble removal device having the above configuration, it is preferable to provide a bubble outflow suppression member (for example, the wire mesh 65 and the downward wall 66 in the embodiment) that suppresses the outflow of bubbles in the liquid that has flowed into the casing internal flow path space into the internal flow path of the suction side piping. [Effects of the Invention]

[0011] According to the filter device of the present invention, the suction side pipe The flow passage extends from an inlet opening through which the liquid flows to an outlet opening through which the liquid that has flowed into the inlet opening flows, and forms a flow of the liquid from the inlet opening to the outlet opening. The liquid pump comprises a casing member having a casing internal flow path space and a bubble storage space formed above the casing internal flow path space for storing bubbles that rise to the surface from the liquid flowing through the casing internal flow path space, a bubble discharge pipe having one end connected to the casing member and a bubble discharge flow path communicating with the bubble storage space, and a bubble suction device connected to the other end of the bubble discharge pipe for sucking and discharging bubbles in the bubble storage space via the bubble discharge flow path. This allows bubbles to be separated and stored from the liquid flowing through the internal flow path of the suction-side pipe in the casing member and then forcibly removed by the bubble suction device, thereby suppressing the generation of abnormal noise caused by bubbles in the liquid in the liquid pump.

[0012] In the bubble removal device according to the present invention, it is preferable that the cross-sectional area of the casing internal flow path space perpendicular to the direction of liquid flow is larger than the cross-sectional area of the internal flow path of the suction-side piping perpendicular to the direction of liquid flow. With this configuration, the flow velocity of the liquid in the casing internal flow path space is reduced, thereby lengthening the time it takes for the liquid to flow out of the casing internal flow path space. This allows more time for bubbles to rise from the liquid, allowing more bubbles to be collected.

[0013] In the bubble removal device according to the present invention, when the filter device provided in the liquid supply system is a cartridge-type filter device having a filter-side connector that is detachably connectable to a piping-side connector provided in the suction-side piping, the casing member has an inlet-side connector that is connectable to the piping-side connector and an outlet-side connector that is connectable to the filter-side connector. With this configuration, it is possible to add the bubble removal device to an existing liquid supply system that has a cartridge-type filter device, as needed.

[0014] In the bubble removal device according to the present invention, the position of the inlet through which the liquid flows into the casing internal flow path space and the position of the outlet through which the liquid flows out of the casing internal flow path space are preferably offset in a direction perpendicular to the flow direction of the liquid in the casing internal flow path space. With this configuration, when the casing internal flow path space is installed horizontally, the time from when the liquid flows into the casing internal flow path space to when it flows out can be extended by installing the inlet higher in the vertical direction than the outlet in the vertical direction. This allows more time for bubbles to rise from the liquid, allowing more bubbles to be collected.

[0015] The bubble removal device according to the present invention preferably includes a bubble outflow suppression member that suppresses the outflow of bubbles in the liquid that has flowed into the casing internal flow path space into the internal flow path of the suction-side piping. With this configuration, more bubbles in the liquid can be retained within the casing internal flow path space and the bubble storage space, thereby increasing the amount of bubbles to be removed. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing a schematic configuration of a liquid supply system provided with a bubble removal device according to the present invention; [Figure 2]FIG. 2 is a cross-sectional view of a casing member constituting the air bubble removing device, and a cartridge connecting portion and a filter device connected to the casing member. [Figure 3] FIG. 2 is a front view of a casing member of the air bubble removing device. [Figure 4] 4 is a diagram for explaining the movement direction of the mission oil and air bubbles passing through the air bubble removal device. FIG. [Figure 5] 10 is a diagram showing the installation position of a wire mesh provided as a bubble outflow suppression member on a casing member of the bubble removal device. FIG. [Figure 6] 10 is a diagram showing the installation position of a downward wall provided as a bubble outflow suppression member on a casing member of the bubble removal device. FIG. [Figure 7] 10 is a cross-sectional view of a casing member having a structure that allows a filter device to be attached and detached from above in the bubble removing device. FIG. [Figure 8] 10 is a cross-sectional view of a casing member having a structure that allows a filter device to be attached and detached from below in the bubble removing device. FIG. [Figure 9] 10 is a cross-sectional view of a casing member that allows the air bubble removal device to be attached to a filter inlet pipe that constitutes a suction pipe of a hydraulic circuit. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] A preferred embodiment of the present invention will be described below with reference to the drawings. In the following description, a transmission is used for a hydrostatic transmission (HST) 112 and an auxiliary transmission (gear transmission) 121 mounted on an agricultural machine such as a tractor as shown in FIG. In this example, the bubble removal device according to the present invention is applied to a liquid supply system that supplies oil. Here, the above-mentioned transmission oil is used as hydraulic oil in the hydrostatic continuously variable transmission 112 and as lubricating oil in the auxiliary transmission.

[0018] 1, the first hydraulic pump 110 and the second hydraulic pump 120 are connected to an intake pipe 101 (a filter inlet pipe 102 and a filter outlet pipe 103, which will be described later), and one end of the intake pipe 101 branches into two and is connected to the first hydraulic pump 110 and the second hydraulic pump 120, and the other end is inserted into an oil pan 130. This allows the first hydraulic pump 110 to supply mission oil sucked from the oil pan 130 through the intake pipe 101 to a hydrostatic continuously variable transmission 112. The second hydraulic pump 120 is connected to the intake pipe 101. Transmission oil is sucked from an oil pan 130 through 101 and supplied to the auxiliary transmission 121.

[0019] A relief valve 111 is provided between the first hydraulic pump 110 and the hydrostatic continuously variable transmission 112. As a result, when the hydraulic pressure of the mission oil supplied to the hydrostatic continuously variable transmission 112 exceeds a predetermined pressure, the relief valve 111 opens to return a portion of the mission oil to the oil pan 130, thereby preventing the hydraulic pressure from exceeding the predetermined pressure. In addition, the mission oil supplied to the auxiliary transmission 121 is configured to return to the oil pan 130 after passing through a flow path formed in the auxiliary transmission 121.

[0020] A filter device 30 is provided in the suction side pipe 101, which is arranged between the oil pan 130 and the first and second hydraulic pumps 110 and 120. The filter device 30 filters the mission oil flowing through the internal flow path of the suction side pipe 101 to remove foreign matter such as metal dust and dirt that has become mixed in with the mission oil. A cartridge connection part 50 is provided in the suction side pipe 101 to make the filter device 30 detachable from the suction side pipe 101, and the filter device 30 is a cartridge-type filter device that can be detachably attached to the cartridge connection part 50.

[0021] The cartridge connection part 50 has a pipe-side connection part that can be connected to a filter-side connection part of the filter device 30. When the filter-side connection part and the pipe-side connection part are connected, mission oil sucked from the oil pan 130 can flow from the suction-side pipe 101 to the filter device 30 via the cartridge connection part 50, and mission oil filtered by the filter device 30 can flow out via the cartridge connection part 50 to the suction-side pipe 101 that is connected to the first hydraulic pump 110 and the second hydraulic pump 120. Here, of the suction-side pipe 101, the suction-side pipe 101 that extends from the oil pan 130 to the cartridge connection part 50 is referred to as a filter inlet pipe 102, and the suction-side pipe 101 that extends from the cartridge connection part 50 to the first hydraulic pump 110 and the second hydraulic pump 120 is referred to as a filter outlet pipe 103.

[0022] In this embodiment, an air bubble removal device 1 that removes air bubbles mixed in the mission oil flowing through the internal flow path of the suction side pipe 101 is attached between the cartridge connection part 50 and the filter device 30. The air bubble removal device 1 is composed of a casing member 10 in which an internal flow path space 14 and an air bubble storage space 15 are formed, air bubble discharge pipes 104a and 104b that have air bubble discharge flow paths that communicate with the air bubble storage space 15, and vacuum pumps 140a and 140b connected to the air bubble discharge pipes 104a and 104b. Note that although the air bubble removal device of this embodiment is equipped with two vacuum pumps 140a and 140b, the number of vacuum pumps may be one, or three or more.

[0023] Next, the structures of the casing member 10, the filter device 30, and the cartridge connection part 50 will be described with reference to Figure 2. Here, it is assumed that the cartridge connection part 50 is provided in a horizontal position relative to the body frame of the agricultural machine, etc. Therefore, the casing member 10 and the filter device 30 are also attached in a horizontal position relative to the cartridge connection part 50. In the following description, the directions of the up and down arrows shown in Figure 2 will be referred to as the up and down direction (vertical direction), and the directions of the left and right arrows will be referred to as the left and right direction (horizontal direction).

[0024] 2, the cartridge connection part 50 has a shape in which the central axis of a hollow cylinder is tilted sideways, and an inlet 52 that connects to the filter inlet pipe 102 is formed on the bottom surface 51 on the suction pipe side, and an outlet 54 that discharges the mission oil that has flowed in from the inlet 52 is formed on the bottom surface 53 on the filter device side. An inlet space 56 is formed by the bottom surface 51 on the suction pipe side, the bottom surface 53 on the filter device side, and an inner surface 55 of the cartridge connection part 50, and The inflowing mission oil flows into the inlet space 56. Inlet passages 57 leading from the inlet space 56 to the outlet 54 are formed in the upper and lower parts of the bottom surface 53 on the filter device side, so that the mission oil that flows into the inlet space 56 passes through the inlet passages 57 and flows out from the outlet 54.

[0025] A cylindrical first connecting portion 58 is protruded from the outer surface (the right surface in the drawing) of the filter device side bottom surface 53 along the central axis indicated by the dashed line. The first connecting portion 58 has a leading end formed on the outer peripheral surface thereof with a male thread 58a that is engaged with a female thread 36a formed on the inner peripheral surface of the protruding portion 36 of the filter device 30, which will be described later. A cylindrical second connecting portion 59 is protruded from the inner surface (the left surface in the drawing) of the filter device side bottom surface 53 along the central axis indicated by the dashed line. The second connecting portion 59 penetrates the suction pipe side bottom surface 51 and connects to the filter outlet pipe 103 shown in FIG. 1 . An outlet passage 60 is formed through the first connecting portion 58, the filter device side bottom surface 53, and the second connecting portion 59. Mission oil filtered by the filter device 30 flows through the outlet passage 60 to the filter outlet pipe 103. A sealing member (not shown), such as a gasket, that maintains liquid tightness is provided between the bottom surface 51 on the intake pipe side and the second connecting portion 59 to prevent the transmission oil in the inflow space 56 from leaking to the outside.

[0026] Next, the filter device 30 includes a cylindrical filter case 31 with a bottom that opens to the left, a filter element 40 provided inside the filter case 31, a substantially disk-shaped cover member 32 attached to cover the left opening of the filter case 31, a substantially annular cover fixing member 33 joined to the left side of the cover member 32, and a ring-shaped first gasket 34 (a sealing member that maintains liquid tightness) attached to the left side of the cover fixing member 33. The cover member 32 and the cover fixing member 33 are joined by spot welding or the like. The cover fixing member 33 is attached to the filter case 31 by bending and crimping the outer peripheral end of the cover fixing member 33 together with the outer peripheral end of the filter case 31. This forms an element installation space 35 inside the filter case 31 in which the filter element 40 is disposed.

[0027] A cylindrical protrusion 36 that protrudes to the right is provided in the center of the cover member 32, and a female thread 36a is formed on the inner circumferential surface of the protrusion 36. This female thread 36a is threadedly engaged with a male thread 58a formed on the tip of a first connecting portion 58 of the cartridge connecting portion 50. As a result, by inserting the tip of the first connecting portion 58 into the protrusion 36 and threading the male thread 58a into the female thread 36a, the cover member 32 can be detachably attached to the cartridge connecting portion 20. A plurality of communication holes 37 are formed in the cover member 32 so as to surround the protrusion 36 and penetrate the cover member 32 in the left-right direction.

[0028] The filter element 40 includes a cylindrical tube member 41, a filter material 42 attached to the outer peripheral surface of the tube member 41, a disk-shaped left end plate 43 attached to the left ends of the tube member 41 and the filter material 42, and a right end plate 44 attached to the right ends of the tube member 41 and the filter material 42. The tube member 41 is a member for supporting the filter material 42, which is formed into a cylindrical shape from a punched sheet or the like having a large number of small holes 41a. The filter material 42 is formed into a cylindrical shape (with a chrysanthemum-shaped cross section) by folding, for example, cellulose, chemical fiber, or the like into an accordion-like (pleated) shape, and is configured to capture foreign matter in the transmission oil.

[0029] The tube member 41 and the filter medium 42 are sandwiched between left and right end plates 43, 44, and an internal space is formed surrounded by the inner peripheral surface of the tube member 41 and the left and right end plates 43, 44. When the filter element 40 is disposed in the element disposing space 35 in the filter case 31, the element disposing space 35 is defined as the space outside the filter medium 42 (this space is called the "space outside"). The inner space of the filter medium 42 and the tube member 41 (referred to as an inflow space 35a) is partitioned into an inner space of the filter medium 42 and the tube member 41 (referred to as an outflow space 35b).

[0030] An opening is formed in the center of the left end plate 43, penetrating the left-right direction and communicating with the internal space (outflow space 35b) of the filter medium 42 and tube member 41. The filter element 40 is biased leftward by a spring member 38 provided between the left end plate 43 and the right end plate 44 within the filter case 31, and is disposed in the element disposition space 35 within the filter case 31 while being pressed against the right side surface of the cover member 32 and fixed thereto. A ring-shaped second gasket 39 is provided between the left end plate 43 and the cover member 32. The second gasket 39 is a sealing member that separates the unfiltered (primary side) mission oil from the filtered (secondary side) mission oil. When the filter element 40 is disposed in the element disposition space 35 in this manner, the protrusion 36 of the cover member 32 is inserted into the opening in the left end plate 43.

[0031] Next, the structure of the casing member 10 will be described with reference to FIG. 3 in addition to FIG. 2. FIG. 3 is a front view of the casing member 10 as viewed from the cartridge connection portion 50 side in FIG. 2 (the left side in FIG. 2). Note that when describing with reference to FIG. 3, the up, down, left, and right directions will be described with the directions of the up and down arrows in FIG. 3 as the up and down directions (vertical directions), the direction of the left arrow as the back direction, and the direction of the right arrow as the front direction. Here, the back direction in FIG. 3 corresponds to the back direction with respect to the plane of FIG. 2, and the front direction in FIG. 3 corresponds to the front direction with respect to the plane of FIG. 2. The cross-sectional view of the casing member 10 shown in FIG. 2 shows the cross section AA in FIG. 3.

[0032] The casing member 10 is composed of a main body 11 and a lid 20 that covers an opening at the top of the main body 11. The lid 20 is fixed to the main body 11 with four screws 21. The main body 11 is a substantially rectangular parallelepiped block. In this embodiment, as shown in FIG. 3, the side surfaces are sloped inward halfway, and the width of the top is narrower than the width of the bottom. Note that the shape of the main body 11 is not limited to this. For example, the side surfaces of the main body 11 may be vertical, and the width of the top and the bottom may be the same. The main body 11 has a space extending from an inlet opening 12 on the surface facing the cartridge connection portion 50 (hereinafter also referred to as the "inlet surface of the main body 11") to an outlet opening 13 on the surface facing the filter device 30 (hereinafter also referred to as the "outlet surface of the main body 11"). The area of this space, excluding a secondary-side flow passage member 16 and a support portion 17 (see FIG. 3), which will be described later, forms an internal flow passage space 14 (a flow passage for the primary-side transmission oil). An approximately rectangular parallelepiped-shaped space is formed at the top of the internal flow path space 14, and this space and the space formed on the inner surface of the lid portion 20 form an air bubble storage space 15 for collecting air bubbles in the mission oil flowing through the internal flow path space 14.

[0033] The top surface of the lid 20 is provided with outlets 22a and 22b for connecting the bubble storage space 15 to the bubble discharge flow paths of the bubble discharge pipes 104a and 104b shown in Fig. 1. The bubble discharge pipes 104a and 104b are attached to the outlets 22a and 22b using the joints 105a and 105b shown in Fig. 1. A bubble storage space gasket 23 is provided on the surface of the lid 20 that abuts against the upper part of the main body 11. When the lid 20 is fixed to the main body 11 with the screws 21, the abutting surface between the lid 20 and the upper part of the main body 11 is kept liquid-tight.

[0034] In the space extending from the inlet opening 12 to the outlet opening 13, the secondary-side flow passage member 16 is supported on the central axis (indicated by the dashed line in FIG. 2) of the casing member 10 by a support portion 17 shown in FIG. 3. The secondary-side flow passage member 16 is a substantially cylindrical member, and forms a secondary-side flow passage space 18 through which the mission oil (secondary-side mission oil) filtered by the filter device 30 flows into the outflow passage 60 of the cartridge connection portion 50. The end of the member 16 on the filter device 30 side is referred to as the distal end, and the end of the secondary flow path member 16 on the cartridge connection portion 50 side is referred to as the proximal end.

[0035] The tip of the secondary-side flow path member 16 protrudes from the outflow surface of the main body 11. This tip has substantially the same shape as the first connecting portion 58 of the cartridge connecting portion 50, and a male thread 16a similar to the male thread 58a is formed on the outer circumferential surface of the tip. Therefore, the male thread 16a formed on the tip of the secondary-side flow path member 16 can be threadedly engaged with the female thread 36a formed on the inner circumferential surface of the protruding portion 36 of the filter device 30.

[0036] The opening surface of the base end of the secondary-side flow passage member 16 is flush with the inlet surface of the main body 11, and the inner diameter of the base end is the same size as the inner diameter of the protruding portion 36 of the filter device 30. A female thread 16b is formed on the inner circumferential surface of the base end of the secondary-side flow passage member 16. The female thread 16b is similar to the female thread 36a formed on the inner circumferential surface of the protruding portion 36 of the filter device 30, allowing the tip of the first connecting portion 58 of the cartridge connecting portion 50 to be inserted into the base end of the secondary-side flow passage member 16 and the male thread 58a to be threaded into the female thread 16b. As shown in FIG. 3 , a ring-shaped gasket 19 is provided on the outer circumferential side of the inlet opening 12 on the inlet surface of the main body 11 to prevent transmission oil flowing out from the outlet 54 of the cartridge connecting portion 50 from leaking to the outside.

[0037] With the above structure, the mission oil that flows through the inlet passage 57 of the cartridge connecting portion 50 into the inlet opening 12 of the casing member 10 flows through the internal flow path space 14 into the filter device 30. In this embodiment, the cross-sectional area of the internal flow path space 14 in the casing member 10 perpendicular to the direction of flow of the mission oil is larger than the cross-sectional area of the inlet passage 57 in the cartridge connecting portion 50 perpendicular to the direction of flow of the mission oil.

[0038] 4 shows a cross-sectional view of the cartridge connecting portion 50, the casing member 10, and the filter device 30 in a state in which the male thread 58a formed on the first connecting portion 58 of the cartridge connecting portion 50 is threadedly engaged with the female thread 16b formed on the inner peripheral surface of the base end of the secondary-side flow path member 16, and the male thread 16a of the secondary-side flow path member 16 is threadedly engaged with the female thread 36a of the filter device 30. In this figure, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0039] 4 are the same as those in FIG. 2. The hatching with thick dots indicates the area covered by the mission oil (primary-side mission oil) before it is filtered by the filter device 30, and the hatching with thin dots indicates the area covered by the mission oil (secondary-side mission oil) after it is filtered by the filter device 30. The open ellipses in the area covered by the primary-side mission oil (area hatched with thick dots) indicate air bubbles BU. The solid arrows indicate the flow of the mission oil, and the dashed arrows indicate the direction of movement of air bubbles mixed in the mission oil.

[0040] 4, mission oil that flows into the inlet 52 of the cartridge connecting part 50 from the filter inlet pipe 102 shown in FIG. 1 passes through the inlet space 56 and the inlet passage 57 and flows into the internal flow path space 14 of the casing member 10, and then flows through the internal flow path space 14 into the inlet space 35a from the circulation hole 37 provided in the cover member 32 of the filter device 30. Then, the mission oil that passes through the filter material 42 from the inlet space 35a flows into the outlet space 35b, passes through the secondary flow path space 18 formed in the secondary flow path member 16 of the casing member 10, and flows out through the outlet passage 60 of the cartridge connecting part 50 to the filter outlet pipe 103.

[0041] When the mission oil that has flowed into the cartridge connection portion 50 contains air bubbles BU, the air bubbles BU are mixed in the internal flow passage space 14 of the casing member 10, and the air bubbles BU are mixed in the internal flow passage space 14 of the casing member 10. As shown by , the air bubbles BU rise to the surface and are stored in the air bubble storage space 15. Here, as described above, the cross-sectional area of the internal flow path space 14 in the casing member 10 is larger than the cross-sectional area of the inlet passage 57 of the cartridge connection portion 50, so the flow rate of the mission oil decreases in the internal flow path space 14. This allows more time for the air bubbles BU in the mission oil to rise to the air bubble storage space 15, and more air bubbles BU can be collected in the air bubble storage space 15.

[0042] The air bubbles BU accumulated in the air bubble storage space 15 are sucked by the vacuum pumps 140a and 140b shown in FIG. 1 through the air bubble discharge flow paths of the air bubble discharge pipes 104a and 104b and returned to the oil pan 130. In the air bubble removal device of this embodiment, the air bubbles in the mission oil rise within the internal flow path space 14 before reaching the filter device 30 and grow in the air bubble storage space 15, making it easy to remove the air bubbles. In this way, the air bubbles in the mission oil are stored in the air bubble storage space 15 and then forcibly sucked out by the vacuum pumps 140a and 140b, thereby removing the air bubbles mixed in the mission oil. This reduces the amount of air bubbles supplied to the first hydraulic pump 110 and the second hydraulic pump 120 shown in FIG. 1, thereby suppressing abnormal noise generated by the first hydraulic pump 110 and the second hydraulic pump 120.

[0043] A member (a bubble outflow suppression member) for suppressing air bubbles that have flowed into the internal flow path space 14 from flowing out toward the filter device 30 (and ultimately toward the filter outflow pipe 103) may be provided in the internal flow path space 14. An example of this bubble outflow suppression member is shown in FIGS. 5 and 6. In FIGS. 5 and 6, (a) is a front view of the casing member 10 as seen from the cartridge connection portion 50 side, and (b) is a cross-sectional view taken along line AA in (a). In addition, in FIGS. 5 and 6, the same components as those shown in FIGS. 2 and 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0044] 5 is a wire mesh 65 that covers the entire area of the outflow opening 13 and is provided on the outflow opening 13 side of the internal flow path space 14. By providing the wire mesh 65 on the outflow opening 13 side of the internal flow path space 14 in this manner, the mission oil passing through the internal flow path space 14 is allowed to flow toward the filter device 30, while preventing air bubbles in the mission oil from passing toward the filter device 30 and causing the air bubbles to float up along the surface of the wire mesh 65 into the air bubble storage space 15. Note that the mesh size of the wire mesh 65 is preferably as coarse as possible so as to have as little effect as possible on the flow rate of the mission oil in the internal flow path space 14.

[0045] 6 is a downward wall 66, which extends from the upper end of the outflow opening 13 toward the center of the internal flow path space 14 on the outflow opening 13 side of the internal flow path space 14 and partially blocks the upper part of the outflow opening 13. This prevents the bubbles stored in the bubble storage space 15 from flowing out to the filter device 30 and allows more bubbles to be stored in the bubble storage space 15. Note that both the wire mesh 65 shown in FIG. 5 and the downward wall 66 shown in FIG. 6 may be provided in the internal flow path space 14.

[0046] In the above-described bubble removal device, the filter device 30 is attached to the casing member 10 in a detachable manner from the lateral direction, but the filter device 30 may also be attached and detached in a vertical direction. The structure of the casing member 10 that allows the filter device 30 to be attached and detached in the vertical direction is shown in Figures 7 and 8. Figures 7 and 8 are cross-sectional views of the casing member 10 and the filter device 30, similar to Figures 2 and 4. In Figures 7 and 8, the same components as those shown in Figure 2 are designated by the same reference numerals, and detailed explanations will be omitted.

[0047] In the casing member 10' shown in FIG. 7, the outlet opening 13 is provided on the upper surface of the casing member 10'. The casing member 10' shown in FIG. 7 is formed such that the tip of the secondary-side flow path member 16' is bent upward to form an L-shaped, approximately cylindrical member. The shape of the tip of the secondary-side flow path member 16' and the length of its upward protrusion are the same as those of the secondary-side flow path member 16 shown in FIG. 2. In the casing member 10' shown in FIG. 7, the mission oil that flows in from the inlet opening 12 changes its flow direction upward at the bent portion of the internal flow path space 14 and flows into the filter device 30 from the outlet opening 13. The mission oil filtered by the filter device 30 flows downward from the tip of the secondary-side flow path member 16', changes its flow direction laterally at the bent portion of the secondary-side flow path member 16', and flows into the outflow passage 60 of the cartridge connection portion 50 shown in FIG. 2.

[0048] In the casing member 10" shown in FIG. 8, the outflow opening 13 is formed on the lower surface of the casing member 10", and the tip of the secondary-side flow path member 16" is an L-shaped, approximately cylindrical member that is bent downward to match this. The shape of the tip of the secondary-side flow path member 16" and the length of its downward protrusion are the same as those of the secondary-side flow path member 16 shown in FIG. 2. In the casing member 10" shown in FIG. 8, the mission oil that flows in from the inlet opening 12 changes its flow direction downward at the bent portion of the internal flow path space 14 and flows into the filter device 30 from the outflow opening 13. In addition, the mission oil filtered by the filter device 30 flows upward from the tip of the secondary-side flow path member 16", changes its flow direction laterally at the bent portion of the secondary-side flow path member 16", and flows into the outflow passage 60 of the cartridge connection portion 50 shown in FIG. 2.

[0049] In the above-described bubble removal device, the casing member 10 is in the form of a so-called adapter and is inserted between the cartridge connection part 50 and the filter device 30, but it may also be provided in the filter inlet pipe 102 between the oil pan 130 and the cartridge connection part 50. An example of a casing member in such a case is shown in Fig. 9. In the following explanation, the directions of the up and down arrows in Fig. 9 will be referred to as the up and down direction (vertical direction), and the directions of the left and right arrows will be referred to as the left and right direction (horizontal direction).

[0050] The casing member 70 in this figure is composed of a main body 71 that has a shape of a hollow cylinder with its central axis tilted sideways, and a lid that covers an opening formed at the top of the main body 71. Here, the structure of the lid is similar to that of the lid 20 shown in Figure 2, so the same reference numerals are used for the various parts of the lid 20 and detailed explanations will be omitted.

[0051] 9, the main body 71 is disposed in the filter inlet pipe 102 shown in Fig. 1 with its side facing horizontally, and an inlet 72 through which mission oil sucked from the oil pan 130 flows in is formed in the bottom surface on the left side of the main body 71 (on the oil pan 130 side). In addition, an outlet 73 through which mission oil flows out to the filter inlet pipe 102 connected to the cartridge connection part 50 is formed in the bottom surface on the right side of the main body 71 (on the cartridge connection part 50 side). The space from the inlet 72 to the outlet 73 forms an internal flow path space 74, and an air bubble storage space 75 is formed above the internal flow path space 74.

[0052] Unlike the casing member 10 shown in FIG. 2, the casing member 70 shown in FIG. 9 does not include a component such as the secondary flow passage member 16 inside the main body 71. Furthermore, the inlet 72 and the outlet 73 are not coaxial but are offset vertically. Therefore, when the casing member 70 is attached to the filter inlet pipe 102, the inlet 72 is attached higher than the outlet 73, thereby lengthening the time it takes for the mission oil to pass through the internal flow passage 74. This allows more time for air bubbles to rise from the mission oil, allowing more air bubbles to be collected. Alternatively, as an alternative to the configuration shown in FIG. 9, the casing member 10 and the filter device 30 may be integrated to form a filter device 30 equipped with the casing member 10.

[0053] In the above embodiment, the present invention has been described as being applied to a liquid supply system that supplies mission oil to a hydrostatic continuously variable transmission 112 and an auxiliary transmission 121 that supply mission oil to agricultural machinery such as a tractor, but the present invention can also be applied to a liquid supply system that supplies hydraulic oil to various hydraulic actuators of a work vehicle, for example. [Explanation of symbols]

[0054] 1. Air bubble removal device 10,70 Casing member 11 Main body 14 Internal flow space 15 Bubble storage space 16 Secondary flow path member 16a male thread 16b female thread 20 Lid 30 Filter device 36 Protrusion 36a female thread 50 Cartridge connection part 57 Inflow passage 72 Inlet 73 Outlet 101 Suction side piping 102 Filter inlet piping 103 Filter outlet piping 104a, 104b Air bubble exhaust pipe 110 First hydraulic pump 112 Hydrostatic continuously variable transmission 120 Second hydraulic pump 121 Auxiliary transmission 130 Oil pan 140a, 140b Vacuum pump

Claims

1. In a liquid supply system in which liquid stored in a tank is sucked by a liquid pump and supplied to a supply target, there is provided a bubble removal device that is provided midway through a suction-side pipe connecting the tank and the liquid pump, and that removes bubbles in the liquid flowing through an internal flow path of the suction-side pipe, a casing member having a casing internal flow path space that extends from an inflow opening, through which liquid flowing through the suction side piping flows in, to an outflow opening, through which the liquid that has flowed into the inflow opening flows out, and that forms a flow of liquid from the inflow opening to the outflow opening, and a bubble storage space that is formed above the casing internal flow path space and that stores bubbles that rise to the surface from the liquid flowing through the casing internal flow path space; a bubble discharge pipe having one end connected to the casing member and having a bubble discharge flow path communicating with the bubble storage space; a bubble suction device connected to the other end of the bubble discharge pipe, which sucks and discharges bubbles in the bubble storage space through the bubble discharge flow path.

2. 2. The bubble removing device according to claim 1, wherein the cross-sectional area of the casing internal flow path space perpendicular to the direction of liquid flow is larger than the cross-sectional area of the internal flow path of the suction side pipe perpendicular to the direction of liquid flow.

3. the liquid supply system includes a filter device that filters the liquid flowing through the internal flow path of the suction side pipe; the filter device is a cartridge-type filter device having a filter-side connecting part that is detachably connectable to a piping-side connecting part provided on the suction-side piping, The casing member is an inlet-side connection portion connectable to the piping-side connection portion; 3. The bubble removing device according to claim 1, further comprising an outlet-side connector connectable to the filter-side connector.

4. A bubble removal device as described in either claim 1 or 2, characterized in that the position of the inlet through which the liquid flows into the casing internal flow path space and the position of the outlet through which the liquid flows out of the casing internal flow path space are offset in a direction perpendicular to the flow direction of the liquid in the casing internal flow path space.

5. A bubble removal device as described in any one of claims 1 to 4, characterized in that it is provided with a bubble outflow suppression member that suppresses bubbles in the liquid that has flowed into the casing internal flow path space from flowing out into the internal flow path of the suction side piping.

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