JP7725282B2 - Air bubble removal device - Google Patents

Description

The present invention relates to a bubble removal device that removes bubbles from liquid flowing through the internal flow path of a pipe.

Lubricating oils used in various machines and hydraulic oils flowing through the hydraulic circuits of industrial hydraulic equipment can become contaminated with metal dust, dirt, and other foreign matter during operation of the machines or industrial hydraulic equipment. In such cases, these contaminants can damage the machines or industrial hydraulic equipment. Therefore, to remove these contaminants, 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 with an inlet and an outlet, and a filter element (filter material) installed within the filter case. As a result, as the lubricating oil, hydraulic oil, etc. passes through the filter device, foreign matter can be captured and removed from the filter material surface and filter layer of the filter element installed within the filter case.

JP 2014-188430 A

In agricultural machinery, construction machinery, and other equipment, air bubbles can form in the lubricating oil or hydraulic oil during the lubrication process of the transmission due to factors such as air being drawn in by the transmission gears and vibrations that occur during operation. When these air bubbles flow into the filter device along with the lubricating oil, they can accumulate in certain locations inside the filter case, causing air pockets, or as they pass through the filter element, the bubbles can grow larger due to the internal structure of the filter material. When lubricating oil containing large air bubbles leaves the filter device and is supplied to the hydraulic pump, the hydraulic pump can produce abnormal noise due to air entrapment. Furthermore, air bubbles in the lubricating oil can cause problems such as reduced hydraulic power and poor lubrication.

The present invention was made in consideration of these issues, 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 abnormal noise caused by air entrapment in hydraulic pumps.

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) that stores liquid 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) that connects the tank and the liquid pump, and removing bubbles in liquid flowing through an internal flow path of the suction side pipe, the bubble removal device extending from an inflow opening through which liquid flowing through the suction side pipe flows in to an outflow opening through which the liquid that has flowed into the inflow opening flows out, and 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) that forms the casing internal flow path space, and a bubble storage space (e.g., bubble storage space 15 in the embodiments) that is formed above the casing internal flow path space and stores bubbles that rise to the surface in the liquid flowing through the casing internal flow path space; a bubble discharge pipe (e.g., bubble discharge pipes 104a, 104b in the embodiments) that is connected at one end to the casing member and has a bubble discharge flow path that communicates with the bubble storage space; and a bubble suction device (e.g., vacuum pumps 140a, 140b in the embodiments) that is connected at the other end of the bubble discharge pipe and sucks and discharges bubbles in the bubble storage space via the bubble discharge flow path.

In a bubble removal device configured as described above, 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 (e.g., inflow flow path 57 in the embodiment).

In the bubble removal device configured as described above, the liquid supply system includes a filter device (e.g., filter device 30 in the embodiment) that filters the liquid flowing through the internal flow path of the suction side piping. The filter device is a cartridge-type filter device having a filter side connector (e.g., protrusion 36 and female thread 36a in the embodiment) that is detachably connectable to a piping side connector (e.g., cartridge connector 50 in the embodiment) provided on the suction side piping. The casing member preferably includes an inlet side connector (e.g., the base end of secondary side flow path member 16 and female thread 16b in the embodiment) that is connectable to the piping side connector, and an outlet side connector (e.g., the base end of secondary side flow path member 16 and male thread 16a in the embodiment) that is connectable to the filter side connector.

In a bubble removal device configured as described above, 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.

In a bubble removal device configured as described above, it is preferable to include a bubble outflow suppression member (e.g., the wire mesh 65 and the descending 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.

The filter device according to the present invention includes a casing member having an internal flow path space extending from an inlet opening through which liquid flowing in a suction-side pipe flows to an outlet opening through which the liquid flowing into the inlet opening flows out, 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 connected at one end to the casing member and having a bubble discharge flow path communicating with the bubble storage space, and a bubble suction device connected at 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 in the casing member from the liquid flowing in the internal flow path of the suction-side pipe, and the stored bubbles can be forcibly removed by the bubble suction device, thereby suppressing the generation of abnormal noise caused by bubbles in the liquid in the liquid pump.

In the bubble removal device of the present invention, it is preferable that the cross-sectional area of the casing internal flow path space perpendicular to the liquid flow direction is larger than the cross-sectional area of the suction-side piping internal flow path perpendicular to the liquid flow direction. This configuration reduces the flow rate of the liquid in the casing internal flow path space, 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.

In the bubble removal device according to the present invention, if 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 pipe-side connector provided in the suction-side pipe, the casing member preferably has an inlet-side connector that is connectable to the pipe-side connector and an outlet-side connector that is connectable to the filter-side connector. With this configuration, the bubble removal device can be added as needed to an existing liquid supply system that has a cartridge-type filter device.

In the bubble removal device according to the present invention, it is preferable 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. With this configuration, when the casing internal flow path space is installed facing 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 so that its vertical position is higher than the vertical position of the outlet. This allows more time for bubbles to rise from the liquid, allowing more bubbles to be collected.

The bubble removal device according to the present invention preferably includes a bubble outflow suppression member that prevents bubbles in the liquid that has flowed into the casing's internal flow path space from escaping into the internal flow path of the suction-side piping. This configuration allows more bubbles in the liquid to be retained within the casing's internal flow path space and the bubble storage space, thereby increasing the amount of bubbles removed.

1 is a diagram showing a schematic configuration of a liquid supply system provided with a bubble removal device according to the present invention; 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. FIG. 2 is a front view of a casing member of the air bubble removing device. 4 is a diagram for explaining the movement direction of the mission oil and air bubbles passing through the air bubble removal device. FIG. 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. 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. 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. 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. 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.

A preferred embodiment of the present invention will be described below with reference to the drawings. In the following description, an example is given in which the bubble removal device according to the present invention is applied to a liquid supply system that supplies mission oil to a hydrostatic continuously variable transmission (HST) 112 and an auxiliary transmission (gear transmission) 121 mounted on an agricultural machine such as a tractor, as shown in Fig. 1. Here, the above-mentioned mission oil is used as hydraulic oil in the hydrostatic continuously variable transmission 112 and as lubricating oil in the auxiliary transmission.

1 , a first hydraulic pump 110 and a 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 drawn from the oil pan 130 through the intake pipe 101 to the hydrostatic continuously variable transmission 112. In addition, the second hydraulic pump 120 supplies mission oil drawn from the oil pan 130 through the intake pipe 101 to the auxiliary transmission 121.

A relief valve 111 is provided between the first hydraulic pump 110 and the hydrostatic continuously variable transmission 112. As a result, if the hydraulic pressure of the mission oil supplied to the hydrostatic continuously variable transmission 112 exceeds a predetermined pressure, the relief valve 111 opens and returns some of the mission oil to the oil pan 130, 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 within the auxiliary transmission 121.

A filter device 30 is provided in the intake 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 intake pipe 101, removing foreign matter such as metal dust and debris that has become mixed in with the mission oil. A cartridge connection portion 50 is provided in the intake pipe 101 to allow the filter device 30 to be detachably attached to the intake pipe 101, and the filter device 30 is a cartridge-type filter device that can be detachably attached to the cartridge connection portion 50.

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

In this embodiment, an air bubble removal device 1 is installed between the cartridge connection portion 50 and the filter device 30 to remove air bubbles mixed in with the mission oil flowing through the internal flow path of the suction side pipe 101. 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, 104b having air bubble discharge flow paths communicating with the air bubble storage space 15, and vacuum pumps 140a, 140b connected to the air bubble discharge pipes 104a, 104b. Note that while the air bubble removal device in this embodiment is equipped with two vacuum pumps 140a, 140b, the number of vacuum pumps may be one, or three or more.

Next, the structures of the casing member 10, filter device 30, and cartridge connection part 50 will be described with reference to Figure 2. Here, it is assumed that the cartridge connection part 50 is mounted in a horizontal position relative to the body frame of the agricultural machine. Therefore, the casing member 10 and 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 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).

2, the cartridge connection part 50 has a shape like a hollow cylinder with its central axis tilted sideways, with an inlet 52 connected to the filter inlet pipe 102 formed in the suction pipe side bottom surface 51, and an outlet 54 through which the mission oil flowing in from the inlet 52 flows out formed in the filter device side bottom surface 53. An inlet space 56 is formed by the suction pipe side bottom surface 51, the filter device side bottom surface 53, and an inner surface 55 of the cartridge connection part 50, and the mission oil flowing in from the inlet 52 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 filter device side bottom surface 53, so that the mission oil flowing in to the inlet space 56 flows through the inlet passage 57 and out from the outlet 54.

A cylindrical first connector 58 is protrudingly molded on the outer surface (the right surface in the figure) of the filter device side bottom surface 53 along the central axis indicated by the dashed line. The first connector 58 connects to the protrusion 36 (described below) of the filter device 30. The outer peripheral surface of the tip of the first connector 58 is formed with a male thread 58a that engages with the female thread 36a formed on the inner peripheral surface of the protrusion 36 of the filter device 30 (described below). A cylindrical second connector 59 is protrudingly molded on the inner surface (the left surface in the figure) of the filter device side bottom surface 53 along the central axis indicated by the dashed line. The second connector 59 penetrates the intake 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 connector 58, the filter device side bottom surface 53, and the second connector 59. Mission oil filtered by the filter device 30 flows through the outlet passage 60 to the filter outlet pipe 103. A liquid-tight seal member (not shown), such as a gasket, is provided between the intake pipe side bottom surface 51 and the second connection part 59 to prevent transmission oil from leaking out of the inflow space 56.

The filter device 30 comprises a cylindrical filter case 31 with a bottom that opens to the left, a filter element 40 disposed within 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 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 within the filter case 31 in which the filter element 40 is disposed.

A cylindrical protrusion 36 that protrudes to the right is provided in the center of the cover member 32. A female thread 36a is formed on the inner surface of the protrusion 36. This female thread 36a screws into a male thread 58a formed on the tip of the first connection portion 58 of the cartridge connection portion 50. As a result, the tip of the first connection portion 58 is inserted into the protrusion 36 and the male thread 58a screws into the female thread 36a, allowing it to be detachably attached to the cartridge connection portion 20. Multiple flow holes 37 are formed through the cover member 32 in the left-right direction, surrounding the protrusion 36.

The filter element 40 comprises a cylindrical tube member 41, a filter material 42 attached to the outer 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 numerous small holes 41a. The filter material 42 is formed into a cylindrical shape (with a chrysanthemum-shaped cross section) by folding, for example, cellulose or synthetic fiber into an accordion-like (pleated) shape, and is configured to capture foreign matter in the transmission oil.

The tube member 41 and the filter material 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 arrangement space 35 in the filter case 31, the element arrangement space 35 is divided into a space outside the filter material 42 (referred to as an inflow space 35a) and an internal space of the filter material 42 and the tube member 41 (referred to as an outflow space 35b).

An opening is formed in the center of the left end plate 43, penetrating laterally and communicating with the internal space (outflow space 35b) of the filter material 42 and tube member 41. The filter element 40 is biased leftward by a spring member 38 located between the left end plate 43 and the right end plate 44 within the filter case 31, and is disposed in the element placement space 35 within the filter case 31 while being pressed against the right side of the cover member 32. 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 placement space 35 in this manner, the protrusion 36 of the cover member 32 is inserted into the opening in the left end plate 43.

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

The casing member 10 is composed of a main body 11 and a lid 20 that covers the 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 roughly rectangular block. In this embodiment, as shown in FIG. 3, the side surfaces are sloped inward, 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, forming a rectangular block whose top and bottom widths are the same. The main body 11 has a space extending from the 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 the 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 the secondary flow path member 16 and support portion 17 (see Figure 3), which will be described later, becomes the internal flow path space 14 (the primary side mission oil flow path). A roughly rectangular parallelepiped space is formed above the internal flow path space 14, and this space, together with 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.

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 Figure 1. The bubble discharge pipes 104a and 104b are attached to the outlets 22a and 22b using the joints 105a and 105b shown in Figure 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. This ensures that the abutting surface between the lid 20 and the upper part of the main body 11 is liquid-tight when the lid 20 is fixed to the main body 11 with the screws 21.

Within the space extending from the inlet opening 12 to the outlet opening 13, the secondary-side flow path member 16 described above 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 path member 16 is a substantially cylindrical member, and forms a secondary-side flow path 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 connecting portion 50. Here, the end of the secondary-side flow path member 16 on the filter device 30 side is referred to as the tip end, and the end of the secondary-side flow path member 16 on the cartridge connecting portion 50 side is referred to as the base end.

The tip of the secondary flow path member 16 protrudes from the outflow surface of the main body 11. This tip has approximately the same shape as the first connection portion 58 of the cartridge connection portion 50, and a male thread 16a similar to the male thread 58a is formed on the outer peripheral surface of the tip. Therefore, the male thread 16a formed on the tip of the secondary flow path member 16 can be threaded with the female thread 36a formed on the inner peripheral surface of the protrusion 36 of the filter device 30.

The opening surface of the base end of the secondary flow path 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 flow path 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 flow path member 16 and the male thread 58a to be threaded onto the female thread 16b. As shown in FIG. 3, a ring-shaped gasket 19 is provided on the outer periphery of the inlet opening 12 on the inlet surface of the main body 11 to prevent transmission oil from leaking from the outlet 54 of the cartridge connecting portion 50 to the outside.

With the above structure, mission oil that flows through the inlet passage 57 of the cartridge connection portion 50 and into the inlet opening 12 of the casing member 10 flows through the internal flow path space 14 and 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 mission oil flow is larger than the cross-sectional area of the inlet passage 57 in the cartridge connection portion 50 perpendicular to the direction of mission oil flow.

Figure 4 shows a cross-sectional view of the cartridge connection portion 50, casing member 10, and filter device 30 in a state in which the male thread 58a formed on the first connection portion 58 of the cartridge connection portion 50 is threadedly engaged with the female thread 16b formed on the inner surface of the base end of the secondary flow path member 16, and the male thread 16a of the secondary 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 Figure 2 are designated by the same reference numerals, and detailed explanations will be omitted.

The up, down, left, and right directions in Figure 4 are the same as in Figure 2. Furthermore, the hatching with thick dots indicates the area affected by the mission oil (primary side mission oil) before it is filtered by the filter device 30, and the hatching with light dots indicates the area affected by the mission oil (secondary side mission oil) after it has been filtered by the filter device 30. Furthermore, the open ellipses in the area affected by the primary side mission oil (area hatched with thick dots) indicate air bubbles BU. Furthermore, the solid arrows indicate the flow of mission oil, and the dashed arrows indicate the direction of movement of air bubbles mixed in the mission oil.

In Figure 4, mission oil that flows from the filter inlet pipe 102 shown in Figure 1 into the inlet 52 of the cartridge connection part 50 passes through the inlet space 56 and the inlet passage 57 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 through the flow hole 37 provided in the cover member 32 of the filter device 30. The mission oil then passes through the filter material 42 from the inlet space 35a 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 connection part 50 to the filter outlet pipe 103.

If air bubbles BU are mixed in the mission oil that flows into the cartridge connection portion 50, the air bubbles BU rise to the surface as shown by the dashed arrows when the mission oil passes through the internal flow path space 14 of the casing member 10 and accumulate 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, allowing more air bubbles BU to be collected in the air bubble storage space 15.

Air bubbles BU accumulated in the air bubble storage space 15 are sucked through the air bubble discharge flow path of the air bubble discharge pipes 104a and 104b by the vacuum pumps 140a and 140b shown in FIG. 1 and returned to the oil pan 130. In this embodiment, the air bubble removal device causes air bubbles in the mission oil to 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 bubbles. In this way, air bubbles in the mission oil are collected 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 with 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.

A member (a bubble outflow suppression member) may be provided in the internal flow path space 14 to prevent bubbles that have flowed into the internal flow path space 14 from escaping toward the filter device 30 (and ultimately toward the filter outflow pipe 103). An example of this bubble outflow suppression member is shown in Figures 5 and 6. In Figures 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 the line A-A in (a). In Figures 5 and 6, components similar to those shown in Figures 2 and 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

The bubble outflow suppression member shown in Figure 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 way, 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 air bubbles to float up along the surface of the wire mesh 65 into the air bubble storage space 15. Note that it is preferable that the mesh size of the wire mesh 65 be 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.

The bubble outflow suppression member shown in Figure 6 is a downward wall 66 that 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, partially blocking the upper part of the outflow opening 13. This prevents bubbles accumulated in the bubble storage space 15 from escaping 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 Figure 5 and the downward wall 66 shown in Figure 6 may be provided within the internal flow path space 14.

In the above-described bubble removal device, the filter device 30 is attached to the casing member 10 in a manner that allows it to be attached and detached laterally. However, the filter device 30 may also be attached and detached vertically. Figures 7 and 8 show the structure of the casing member 10 that allows the filter device 30 to be attached and detached vertically. Similar to Figures 2 and 4, Figures 7 and 8 are cross-sectional views of the casing member 10 and filter device 30. In Figures 7 and 8, components similar to those shown in Figure 2 are designated by the same reference numerals, and detailed descriptions will be omitted.

In the casing member 10′ shown in FIG. 7 , the outflow opening 13 is formed on the upper surface of the casing member 10′, and the tip of the secondary-side flow path member 16′ is a generally L-shaped cylindrical member that bends upward to match the outflow opening 13. 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 through the inlet opening 12 changes its flow direction upward at the bend in the internal flow path space 14 and flows into the filter device 30 through the outlet opening 13. Furthermore, 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 bend in the secondary-side flow path member 16′, and flows into the outflow passage 60 of the cartridge connection portion 50 shown in FIG. 2 .

In the casing member 10" shown in Figure 8, the outflow opening 13 is formed on the underside of the casing member 10", and the tip of the secondary-side flow path member 16" is an L-shaped, approximately cylindrical member that bends downward to match this. Here, 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 Figure 2. In the casing member 10" shown in Figure 8, mission oil that flows in through the inflow opening 12 changes its flow direction downward at the bend in the internal flow path space 14 and flows into the filter device 30 through the outflow opening 13. In addition, 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 bend in the secondary-side flow path member 16", and flows into the outflow passage 60 of the cartridge connection portion 50 shown in Figure 2.

In the bubble removal device described above, the casing member 10 is inserted between the cartridge connection portion 50 and the filter device 30 in the form of an adapter, but it may also be provided on the filter inlet pipe 102 between the oil pan 130 and the cartridge connection portion 50. An example of a casing member in such a case is shown in Figure 9. In the following explanation, the directions of the up and down arrows in Figure 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).

The casing member 70 in this figure is composed of a main body 71 shaped like 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.

In Figure 9, the main body 71 is disposed in the filter inlet pipe 102 shown in Figure 1 with its side facing horizontally, and an inlet 72 is formed in the bottom surface on the left side of the main body 71 (the oil pan 130 side), through which mission oil drawn from the oil pan 130 flows in. Furthermore, an outlet 73 is formed in the bottom surface on the right side of the main body 71 (the cartridge connection part 50 side), through which mission oil flows out to the filter inlet pipe 102 connected to the cartridge connection part 50. 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.

In the casing member 70 shown in FIG. 9, unlike the casing member 10 shown in FIG. 2, no component such as the secondary flow passage member 16 is provided inside the main body 71. Furthermore, the inlet 72 and outlet 73 are not positioned on the same axis, but are offset vertically. Therefore, when attaching the casing member 70 to the filter inlet pipe 102, the inlet 72 can be positioned 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.

In the above embodiment, we have described 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 tractors. However, the present invention can also be applied to a liquid supply system that supplies hydraulic oil to various hydraulic actuators in a work vehicle, for example.

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

Claims (5)

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. The bubble removal device described in claim 1, characterized in that the cross-sectional area of the casing internal flow path space perpendicular to the liquid flow direction is larger than the cross-sectional area of the suction side piping internal flow path perpendicular to the liquid flow direction. 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. 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. 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.