Drain plug and drain plug structure

Abstract

To provide a drain plug and drain plug structure that are easy to manufacture and highly durable. [Solution] The drain plug 5 in the drain plug structure 1 has a flange portion 51, a core portion 52 integrally formed with the flange portion 51 and extending from the flange portion 51, and a threaded rib portion 53 integrally formed on the tip side of the core portion 52 and extending spirally around the axis of the core portion 52. The fluid container 2 has a wall portion 21 that partitions the containment space 20, and a drain hole 3 that penetrates the wall portion 21. The screwed rib portion 53 screws into the peripheral edge portion 45 of the drain hole 3, which is the peripheral edge of the main hole portion 30 of the drain hole 3 in the wall portion 21, and as it passes through the drain hole 3 from the outside to the inside of the housing space 20, the drain plug 5 closes the drain hole 3.

Description

[Technical Field]

[0001] The present invention relates to a drain plug for closing a drain hole provided in a fluid container, and a drain plug structure including the fluid container and the drain plug. [Background Art]

[0002] As a drain plug structure including a fluid container provided with a drain hole and a drain plug for closing the drain hole, for example, an oil pan device for a vehicle is known.

[0003] An oil pan device for a vehicle is a device for receiving engine oil in a vehicle. In normal conditions, a drain hole is closed by a drain plug, and engine oil that has flowed into an oil pan serving as a fluid container is stored in the oil pan. When the drain plug is removed from the drain hole at the time of replacing engine oil or the like, the engine oil stored in the oil pan is discharged to the outside of the oil pan through the drain hole.

[0004] As such a drain plug structure, a structure in which the peripheral edge portion of the drain hole of the fluid container and the drain plug are screwed together has been proposed (see, for example, Patent Document 1).

[0005] In the drain plug structure introduced in Patent Document 1, the drain plug 5 is provided with two spiral cam grooves 11, and the oil pan 1 serving as a fluid container is provided with two projections on the inner peripheral surface of the through-hole-shaped drain hole 4. In the drain plug structure, the cam grooves 11 of the drain plug 5 are respectively screwed with the corresponding projections 12 of the oil pan 1. [Prior Art Documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2019-100222 [Overview of the project] [Problems that the invention aims to solve]

[0007] By the way, the drain plug structure described in Patent Document 1 above uses two types of mechanisms to close the drain hole of the fluid container with the drain plug: a screwing mechanism between the cam groove 11 and the projection 12, and an engagement mechanism between the engaging projection 16 and the engaging recess 17.

[0008] More specifically, in the drain plug structure of Patent Document 1, one end of the drain plug 5 (columnar plug body portion 6) is inserted into the drain hole 4, the starting end of each cam groove 11 provided on the drain plug 5 is aligned with each projection 12 provided on the periphery of the drain hole 4, and then the drain plug 5 is rotated by a predetermined amount to screw the cam groove 11 and the projection 12 together, thereby pulling the drain plug 5 towards the drain hole 4.

[0009] Furthermore, the drain plug structure described in Patent Document 1 has an engagement structure that forms a cantilever beam shape. Specifically, in the drain plug structure of Patent Document 1, four cantilever-shaped arc-shaped arm portions 15 are provided along the circumference of the seating flange portion 7 located at the other end of the drain plug 5, and an engaging portion (for example, an engaging projection 16) is formed at the tip of each arc-shaped arm portion 15, which is convex and concave in the direction in which the one end of the drain plug 5, i.e., the columnar plug portion 6, extends. On the other hand, at the bottom of the oil pan 1, engagement portions (for example, engagement recesses 17) that are uneven in the inward-outward direction of the storage space in the oil pan 1 are provided at positions corresponding to each engagement projection 16.

[0010] The corresponding engaging projections 16 and engaging recesses 17 interlock with each other, thereby inhibiting the reverse rotation of the drain plug 5 and preventing it from detaching from the drain hole 4.

[0011] According to the drain plug structure of Patent Document 1 described above, it is possible to block the drain hole provided in the fluid container with a drain plug, and it is also believed that the detachment of the drain plug 5 from the drain hole 4 is suppressed.

[0012] However, in the drain plug structure of Reference 1, the screw mechanism between the cam groove 11 and the projection 12 requires the projection 12 to be formed on the inner circumferential surface of the drain hole 4. The structure of such a drain hole 4 and the fluid container (oil pan 1) having said drain hole 4 is complex, and there is a problem that the cost required to manufacture the fluid container with high molding accuracy will be high.

[0013] Furthermore, the engagement mechanism between the engaging projection 16 and the engaging recess 17 is structurally weak because the arc-shaped arm portion 15 provided on the seating flange portion 7 is cantilevered. In particular, when the fluid container and drain plug are made of resin, as in Patent Document 1, there is a risk that the arc-shaped arm portion 15 may break when the drain plug 5 is rotated to engage the engaging projection 16 and the engaging recess 17 with each other, during vehicle operation, or due to deterioration in durability.

[0014] Therefore, there is a need for drain plug structures of this type that are easy to manufacture and also highly durable.

[0015] This invention has been made in view of the above circumstances, and aims to solve the problem of providing a drain plug structure that is easy to manufacture and has excellent durability. [Means for solving the problem]

[0016] The drain plug structure of the present invention, which solves the above problems, A fluid container having a wall portion that partitions the containment space, a drain hole formed through the wall portion, and a drain plug that closes the drain hole, The drain hole has a main hole portion and a through hole portion located radially outside the main hole portion and communicating with a part of the main hole portion in the circumferential direction. The drain plug has a flange portion, a core portion integrally formed with the flange portion and extending from the flange portion, and a threaded rib portion integrally formed with the tip side of the core portion and extending spirally around the axis of the core portion. When the drain plug blocks the drain hole, The core portion enters the main hole portion, The threaded rib portion that enters the through hole portion engages with the hole periphery portion of the wall portion located at the periphery of the main hole portion, and passes through the drain hole from the outside to the inside of the containment space. In the blocked state in which the drain plug blocks the drain hole, This drain plug structure is characterized in that the flange-side surface of the threaded rib portion and the outer surface of the housing space on the periphery of the hole are in contact with each other.

[0017] Furthermore, the drain plug of the present invention, which solves the above problems, A drain plug for closing a drain hole in a fluid container having a wall portion that partitions a storage space and a drain hole formed through the wall portion, It has a flange portion, a core portion integrally formed with the flange portion and extending from the flange portion, and a threaded rib portion integrally formed on the tip side of the core portion and extending spirally around the axis of the core portion, When closing the drain hole, The core portion enters the main hole portion of the drain hole, The threaded rib portion, which enters a through hole in the drain hole located radially outside the main hole and connected to a part of the circumferential direction of the main hole, screws into the hole periphery portion of the wall portion located at the periphery of the main hole, and passes through the drain hole from the outside to the inside of the containment space. In the blocked state in which the drain plug blocks the drain hole, This drain plug has a flange-side surface on the threaded rib portion that abuts against the outer surface of the housing space at the periphery of the hole. [Effects of the Invention]

[0018] The drain plug and drain plug structure of the present invention are easy to manufacture and also excellent in durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] [Figure 1] It is an explanatory diagram schematically illustrating the outline of the drain plug structure of Example 1. [Figure 2] It is an explanatory diagram schematically illustrating a portion near a drain hole in a fluid container and the drain plug in the drain plug structure of Example 1. [Figure 3] It is an explanatory diagram schematically illustrating a state where the portion near the drain hole in the fluid container of the drain plug structure of Example 1 is viewed from the inner side of an accommodation space. [Figure 4] It is an explanatory diagram schematically illustrating a state where the portion near the drain hole in the fluid container of the drain plug structure of Example 1 is viewed from the outer side of an accommodation space. [Figure 5] It is an explanatory diagram schematically illustrating a state where an O-ring is assembled to the drain plug in the drain plug structure of Example 1. [Figure 6] It is an explanatory diagram schematically illustrating the drain plug in the drain plug structure of Example 1. [Figure 7] It is an explanatory diagram schematically illustrating a molding die for molding the drain plug in the drain plug structure of Example 1. [Figure 8] It is an explanatory diagram schematically illustrating a molding die for molding the portion near the drain hole in the drain plug structure of Example 1. [Figure 9] It is an explanatory diagram schematically illustrating a state where the drain hole of the fluid container in the drain plug structure of Example 1 is closed by the drain plug in a semi-closed state and at the initial stage of a closing operation. [Figure 10] It is an explanatory diagram schematically illustrating a state where the drain hole of the fluid container in the drain plug structure of Example 1 is closed by the drain plug in a semi-closed state and at the initial stage of a closing operation. [Figure 11]This is a schematic diagram illustrating how the drain hole of the fluid container in the drain plug structure of Example 1 is blocked by the drain plug in a semi-blocked state and in the initial stages of the blocking operation. [Figure 12] This is a schematic diagram illustrating how the drain hole of the fluid container in the drain plug structure of Example 1 is blocked by the drain plug during a semi-blocked state and at the end of the blocking operation. [Figure 13] This is a schematic diagram illustrating how the drain hole of the fluid container in the drain plug structure of Example 1 is blocked by the drain plug during a semi-blocked state and at the end of the blocking operation. [Figure 14] This is a schematic diagram illustrating how the drain hole of the fluid container in the drain plug structure of Example 1 is blocked by the drain plug during a semi-blocked state and at the end of the blocking operation. [Figure 15] This is a schematic diagram illustrating the drain plug structure of Embodiment 1, which is in a blocked state and not equipped with a rotation stopper. [Figure 16] This is a schematic diagram illustrating the drain plug structure of Embodiment 1, which is in a blocked state and not equipped with a rotation stopper. [Figure 17] This is a schematic diagram illustrating the drain plug structure of Embodiment 1, which is in a blocked state and not equipped with a rotation stopper. [Figure 18] This is a schematic diagram illustrating the drain plug structure of Embodiment 1, which is in a blocked state and has a rotation-preventing mechanism. [Figure 19] This is a schematic diagram illustrating the drain plug structure of Embodiment 1, which is in a blocked state and has a rotation-preventing mechanism. [Figure 20] This is a schematic diagram illustrating the drain plug structure of Embodiment 1, which is in a blocked state and has a rotation-preventing mechanism. [Figure 21] This is an explanatory diagram illustrating the drain plug in the drain plug structure of Example 2. [Figure 22] This is a schematic diagram illustrating how the drain hole of the fluid container is blocked by the drain plug in the drain plug structure of Example 2. [Figure 23] This is a schematic diagram illustrating how the drain hole of the fluid container is blocked by the drain plug in the drain plug structure of Example 2. [Modes for carrying out the invention]

[0020] The drain plug of the present invention is a drain plug included in the drain plug structure of the present invention. Therefore, when a drain plug is described herein without further explanation, the drain plug included in the drain plug structure of the present invention and the drain plug of the present invention are collectively referred to. Similarly, when a drain plug component is described in this specification without further explanation, the drain plug component included in the drain plug structure of the present invention and the drain plug component of the present invention are collectively referred to.

[0021] The drain plug structure of the present invention comprises a fluid container having a wall portion that partitions a containment space and a drain hole formed through the wall portion, and a drain plug that closes the drain hole.

[0022] The drain hole comprises a main hole portion and a through hole portion located radially outside the main hole portion and communicating with a part of the main hole portion in the circumferential direction. Furthermore, the drain plug has a flange portion, a core portion integrally formed with the flange portion and extending from the flange portion, and a threaded rib portion integrally formed on the tip side of the core portion and extending spirally around the axis of the core portion.

[0023] In the drain plug structure of the present invention, when the drain plug closes the drain hole, The core portion enters the main hole portion, The threaded rib portion that enters the through hole portion screws into the hole periphery portion of the wall portion located around the main hole portion, and passes through the drain hole from the outside to the inside of the containment space.

[0024] The periphery of the hole is the portion of the fluid container wall that is at the periphery of the drain hole, and not the portion on the inner circumferential surface of the drain hole. Therefore, in the drain plug structure of the present invention, the structure of the drain hole is not complex, and the structure of the fluid container having the drain hole is also not complex.

[0025] Therefore, it can be said that the drain plug structure of the present invention is easy to manufacture.

[0026] Furthermore, in the drain plug structure of the present invention, when the drain plug is in a closed state that blocks the drain hole, The surface of the threaded rib portion on the flange side and the surface of the hole periphery portion on the outer side of the housing space are in contact with each other.

[0027] As a result, in the drain plug structure of the present invention, the reverse rotation of the drain plug is inhibited, and the detachment of the drain plug from the drain hole is suppressed.

[0028] Therefore, the drain plug structure of the present invention does not require the provision of a cantilever-shaped arc-shaped arm portion 15 and an engaging projection 16 formed on the arc-shaped arm portion 15, as described in Patent Document 1.

[0029] As a result, the drain plug structure of the present invention can be said to have excellent durability.

[0030] The drain plug and drain plug structure of the present invention will be described below for each of their constituent elements.

[0031] Unless otherwise specified, the numerical range "x~y" described herein includes the lower limit x and the upper limit y. Furthermore, new numerical ranges can be constructed by arbitrarily combining these upper and lower limits, as well as the numerical values ​​listed in the examples. Additionally, any numerical values ​​selected from any of the above numerical ranges can be used as the upper and lower limits of a new numerical range.

[0032] The drain plug structure of the present invention comprises a fluid container and a drain plug.

[0033] The materials for the fluid container and drain plug are not particularly limited, and appropriate materials should be selected as appropriate depending on the application of the fluid container and the type of fluid. The materials for the fluid container and drain plug may be the same or different. Furthermore, each of the fluid container and the drain plug may be made of only one material or of multiple materials.

[0034] For example, the fluid container and drain plug may be made of metal or resin. Since resin materials have excellent moldability and are lightweight, if the drain plug structure of the present invention is for use in a vehicle, it is preferable that at least one of the fluid container and the drain plug is made of resin, and it is particularly preferable that both the fluid container and the drain plug are made of resin.

[0035] In this specification, "resin material" means a material containing 50% by mass or more of resin, and may also include various fillers and additives. It is preferable to use a reinforced plastic containing resin and a reinforcing material made of carbon, glass, ceramics, etc. The shape of the reinforcing material is not particularly limited; various forms such as powder, particulate, or fibrous materials may be appropriately adopted. For example, fiber-reinforced plastic (FRP) using carbon fiber or glass fiber as the reinforcing material can be suitably used.

[0036] The fluid container only needs to have a wall portion that partitions the containment space and a drain hole formed through the wall portion. The drain plug structure of the present invention can be particularly suitably embodied as an oil pan device for a vehicle as described above, but is not limited thereto. The fluid contained in the internal space of the fluid container and discharged to the outside through the drain hole is also not particularly limited.

[0037] The fluid container only needs to have an internal storage space, and may be a tray type without a lid, or a box type with a lid. The fluid container's containment space may include structures other than the fluid itself, such as filters and piping. These structures may be integrated with the fluid container or be separate.

[0038] A drain hole is formed through the wall of the fluid container. This drain hole may be formed at the same time as the wall of the fluid container, or it may be formed in the wall of the fluid container that has been molded beforehand. The drain hole will be discussed later.

[0039] The drain plug has a flange portion, a core portion, and a threaded rib portion. The drain plug is inserted into the drain hole from the front. Therefore, the flange portion is the part of the drain plug located on the rear end in the insertion direction, and can be said to be the part that remains outside the drain hole when the drain plug is in a blocked state.

[0040] Hereafter, as needed, the portion of the drain plug located beyond the flange portion, in other words, the portion where the core and threaded rib portions are integrated, may be referred to as the threaded portion of the drain plug. Additionally, if necessary, a state in which a drain plug is inserted into the drain hole but does not completely block the drain hole may be referred to as a partially blocked state.

[0041] The shape of the flange portion is not particularly limited, but in order to remain reliably outside the drain hole in the above-mentioned blocked state, it is preferable that the radial length of the flange portion be greater than the radial length of the core portion, and more preferably greater than the radial length of the threaded portion. Here, the direction in which the core extends is the axial direction of the drain plug, and the direction perpendicular to the axial direction is the radial direction of the drain plug.

[0042] Because the drain plug screws onto the periphery of the drain hole, it is preferable to provide a structure on the outer side of the flange portion, that is, the side of the flange portion located opposite the tip, for rotating the drain plug in the forward direction to close the drain hole and / or the reverse direction to open the drain hole. Specifically, it is preferable to provide the outer surface of the flange portion with an insertion slot for inserting a tool such as a screwdriver, or a handle.

[0043] The threaded portion of the drain plug may be molded integrally with the flange portion, or it may be molded separately from the flange portion and joined together by welding, bonding, screwing, or other methods. Considering the durability of the drain plug, it is particularly preferable that the threaded portion be molded integrally with the flange portion.

[0044] The core of the threaded portion is the part that extends from the flange portion. Due to the rotation of the drain plug when closing and opening the drain hole, it is preferable that the core portion has a rotationally symmetrical shape, and the radial cross-section of the core portion is preferably a regular polygon with octagons or more, or a perfect circle.

[0045] The threaded rib portion is integrally formed with the tip of the core portion and extends spirally around the axis of the core portion. The shape of the threaded rib portion is not particularly limited; for example, the cross-section obtained by cutting the threaded rib portion with a plane parallel to the axis may be plate-shaped or columnar. Considering the weight reduction of the drain plug structure, a plate-shaped threaded rib portion is preferable.

[0046] Furthermore, it is preferable that the tip portion of the core protrudes even further forward than the tip portion of the threaded rib portion. This tip portion of the core is referred to as the assembly guide portion. If the core has an assembly guide portion, the assembly guide portion passes through the drain hole during the initial stage of the closure operation when the drain hole is closed with a drain plug. This guides the drain plug so that it is assembled at the correct angle relative to the drain hole of the fluid container.

[0047] Here, for example, if the drain plug is assembled at an angle to the drain hole, the screw ribs and core may damage the periphery of the drain hole in the fluid container. However, if the core has an assembly guide, it is guided to be assembled at the correct assembly angle to the drain hole of the fluid container, as described above. This has the advantage of suppressing damage to the fluid container during the occlusion operation.

[0048] The axial length of the assembly guide portion is not particularly limited, but it is preferable that it be 20% or more, 30% or more, or 40% or more of the axial length of the entire core portion. There is no particular upper limit to the axial length of the assembly guide portion, but in order to maintain the threaded rib portion at an appropriate size, it is preferable that the axial length of the assembly guide portion be 80% or less, 70% or less, or 60% or less of the axial length of the entire core portion.

[0049] The axial length of the assembly guide portion is particularly preferably within the range of 2 mm to 5 mm.

[0050] The radial length of the threaded rib portion, that is, the length of the threaded rib portion along the radial direction of the core portion, is also not particularly limited. However, considering the stable closing of the drain hole by the drain plug when the drain hole is closed, it is preferable to have the flange-side surface of the threaded rib portion and the outer surface of the housing space at the periphery of the hole contact over a large area. Also, in order to reduce the weight of the drain plug, it is preferable that the threaded rib portion is not excessively large.

[0051] From these perspectives, it can be said that the radial length of the threaded rib portion is preferably within the range of 30% to 100%, 45% to 90%, or 50% to 80% of the radial length of the core portion. Hereinafter, as needed, the flange-side surface of the threaded rib portion may be referred to as the contact surface of the threaded rib portion, and the outer surface of the housing space at the periphery of the hole may be referred to as the contact surface of the periphery of the hole.

[0052] As previously described, the threaded rib portion extends spirally around the axis of the core. The threaded rib portion may be formed over a range of more than one rotation, i.e., 360° or more, around the axis of the core, or it may be formed over a range of less than one rotation, i.e., not exceeding 360°. Considering the moldability of the drain plug, it is particularly preferable that the threaded rib portion is formed over a range not exceeding 360° around the axis of the core.

[0053] The contact surface of the threaded rib and the contact surface of the hole periphery only need to be in contact when the hole is closed, and this can be point contact, line contact, or surface contact. However, considering the need to stably close the drain hole with the drain plug, it is preferable that the contact surface of the threaded rib and the contact surface of the hole periphery be in line contact, and particularly preferable that they be in surface contact, when the hole is closed.

[0054] The drain hole provided in the wall of the fluid container has a main hole and a through hole. The main hole is the part into which the core of the drain plug is inserted, and its shape should be appropriately determined according to the outer diameter of the core. Preferably, the radial length of the main hole, i.e., the diameter of the main hole, is slightly larger than the outer diameter of the core, i.e., the radial length of the core.

[0055] The through-hole is the portion into which the threaded rib of the drain plug fits. The through-hole is located radially outward from the main hole and connects to a portion of the main hole in the circumferential direction. This allows the core to fit into the main hole and the threaded rib to fit into the through-hole.

[0056] The shape and size of the through-hole should be appropriately set according to the shape of the threaded rib and the positional relationship of the threaded rib to the core.

[0057] Incidentally, the contact surface of the hole periphery in the wall portion contacts the contact surface of the threaded rib portion when it is closed. The contact surface of the hole periphery in the wall portion may be a flat surface or a curved surface. However, in order to ensure a large contact area between the contact surface of the hole periphery and the contact surface of the threaded rib portion, it is preferable to make the contact surface of the hole periphery in the wall portion conform to the shape of the contact surface of the threaded rib portion. Specifically, it is preferable that the contact surface of the hole periphery in the wall portion be a curved surface corresponding to the contact surface of the threaded rib portion.

[0058] Furthermore, the wall portion of the fluid container may have a peripheral cylindrical portion. This peripheral cylindrical portion is a bottomed cylindrical shape that protrudes from the general portion of the wall, and its protrusion direction is from the outside to the inside of the containment space. The bottom wall of the peripheral cylindrical portion is located on the inside side of the containment space.

[0059] If the wall portion has a peripheral cylindrical portion, the drain hole and the hole periphery are provided in the bottom wall of the peripheral cylindrical portion. In this case, when the drain plug is closed, the threaded rib portion of the drain plug is located inside the containment space that passes through the peripheral cylindrical portion. The flange portion of the core of the drain plug, which does not have a threaded rib portion, remains inside the peripheral cylindrical portion. At this time, the flange portion may be inside the peripheral cylindrical portion or it may remain outside the peripheral cylindrical portion, i.e., outside the fluid container.

[0060] Furthermore, in order to suppress loosening of the flange portion when using the drain plug structure of the present invention, it is preferable to place the flange portion in an environment where external forces are unlikely to act on it. Therefore, in the closed state, it is more preferable that the flange portion of the drain plug be located inside the peripheral cylindrical portion.

[0061] In order to position the flange portion of the drain plug inside the peripheral cylindrical portion when the drain is blocked, it is preferable to provide a portion in the peripheral cylindrical portion for housing the flange portion.

[0062] Specifically, it is preferable to provide a general section located on the inside of the housing space and a flange housing section located on the outside of the housing space within the internal space of the peripheral cylindrical section. Furthermore, it is preferable to make the flange housing section larger in diameter than the general section and to provide it in a stepped manner, continuous with the general section. In this case, when closed, the flange portion can be housed in the flange housing portion, and the flange portion is not exposed to the outside.

[0063] For example, when the drain plug structure of the present invention is implemented as an oil pan device, stones or other objects kicked up during vehicle operation may strike the flange portion. In this case, the external force acting on the flange portion may cause damage to the flange portion or rotation of the drain plug. In these cases, there is a risk that the drain plug may detach from the drain hole.

[0064] However, as mentioned above, if the flange portion is housed in the flange housing and not exposed to the outside of the peripheral cylindrical portion, the external force acting on the flange portion as described above is suppressed, which has the advantage of preventing the drain plug from coming off the drain hole.

[0065] The radial length of the flange portion may or may not be constant in the axial direction of the flange portion. For example, the radial length of the flange portion on the tip side, i.e., the screw-fitting side, may be different from the radial length of the flange portion on the outer side, i.e., the side opposite to the tip. Furthermore, for example, if the tip portion of the flange is smaller in diameter than the outer portion, the tip portion of the flange may enter the general portion when it is closed.

[0066] In either case, if the flange portion is positioned inward from the outer end of the flange housing portion when the enclosure is closed, it is possible to place the flange portion inside the peripheral cylindrical portion, i.e., in an environment where external forces are less likely to act.

[0067] In this case, it is preferable to seal the space between the drain plug and the inner surface of the drain hole, and / or the space between the drain plug and the inner surface of the peripheral cylindrical portion, with a sealing material. As the sealing material, an elastic material such as an O-ring is preferably used.

[0068] When sealing the gap between the drain plug and the inner surface of the drain hole with a sealing material, it is preferable that the sealing material be applied to the outer surface of the core portion of the drain plug. On the other hand, when sealing the space between the drain plug and the inner surface of the peripheral cylindrical portion with a sealing material, it is preferable that the sealing material be attached to the outer surface of the core portion or flange portion of the drain plug.

[0069] As described above, in the drain plug structure of the present invention, when the drain plug is closed, the flange-side surface of the threaded rib portion and the outer surface of the housing space on the periphery of the hole come into contact with each other, thereby inhibiting the reverse rotation of the drain plug and preventing the drain plug from coming out of the drain hole.

[0070] Therefore, in the drain plug structure of the present invention, it is not necessary to provide an engagement structure having a cantilever shape as described in Patent Document 1. However, the drain plug structure of the present invention may also have a secondary anti-rotation structure.

[0071] For example, a fluid container may have a peripheral engagement portion projecting toward the flange housing portion at the peripheral edge of the flange housing portion of the peripheral cylindrical portion of the wall portion described above. The flange portion of the drain plug may have a flange engagement portion on its outer edge that engages with the peripheral engagement portion.

[0072] The flange-side engaging portion may, for example, have a convex shape that protrudes radially outward, or a concave shape that is recessed radially inward. In either case, the peripheral engagement portion and the flange-side engagement portion should engage as the drain plug rotates in the forward direction when the drain plug closes the drain hole. Conversely, they should disengage as the drain plug rotates in the reverse direction when the drain plug opens the drain hole.

[0073] The drain plug and drain plug structure of the present invention will be described below with specific examples.

[0074] (Example 1) The drain plug structure of Example 1 is an oil pan structure mounted on a vehicle, and includes an oil pan as a fluid container and a drain plug. Figure 1 is a schematic diagram illustrating the general outline of the drain plug structure of Example 1. Figure 2 is a schematic diagram illustrating the portion of the drain plug structure of Example 1 near the drain hole in the fluid container and the drain plug itself. Figure 3 is a schematic diagram illustrating the portion of the drain plug structure of Example 1 near the drain hole in the fluid container as seen from the inside of the containment space. Figure 4 is a schematic diagram illustrating the portion of the drain plug structure of Example 1 near the drain hole in the fluid container as seen from the outside of the containment space. Figure 5 is a schematic diagram illustrating the assembly of an O-ring to the drain plug in the drain plug structure of Example 1. Figure 6 is a schematic diagram illustrating the drain plug in the drain plug structure of Example 1. Figure 7 is a schematic diagram illustrating the mold used to form the drain plug in the drain plug structure of Example 1. Figure 8 is a schematic diagram illustrating the mold used to form the portion of the drain plug structure of Example 1 near the drain hole. Figures 9 to 20 are schematic diagrams illustrating how the drain hole of the fluid container is blocked by the drain plug in the drain plug structure of Example 1. In each diagram, "inside" refers to the interior of the containment space, and "outside" refers to the exterior of the containment space.

[0075] Figures 1, 2, 4, and 15-20 show the drain plug structure of Example 1 in a blocked state. Figures 9-14 show the drain plug structure of Example 1 in a semi-blocked state, with Figures 9-11 showing the initial stage of the blocking operation and Figures 12-14 showing the final stage of the blocking operation. Figures 15-17 show the state in a blocked state with no anti-rotation mechanism.

[0076] Furthermore, Figures 9, 12, and 15 illustrate a perspective view of the portion of the drain plug structure of Example 1 near the drain hole in the fluid container, viewed from the inside of the containment space; Figures 10, 13, and 16 illustrate a direct view of the portion of the drain plug structure of Example 1 near the drain hole in the fluid container, viewed from the outside of the containment space; and Figures 11, 14, and 17 illustrate a cross-section of the portion of the drain plug structure of Example 1 near the drain hole in the fluid container, viewed at position AA in Figures 10, 13, and 16. In the following embodiments, the clockwise direction and counterclockwise direction refer to the directions in which the drain plug structure is viewed from the outside of the containment space in the fluid container.

[0077] As shown in Figure 1, the drain plug structure 1 of Example 1 comprises a vehicle oil pan as a fluid container 2 and a drain plug 5. The fluid container 2 and drain plug 5 are made of a resin material containing ceramics as a reinforcing material and nylon as a resin, and are injection molded.

[0078] The fluid container 2 has a roughly tray-like shape, with a wall portion 21 that partitions the containment space 20, and a drain hole 3 that penetrates the wall portion 21.

[0079] As shown in Figure 3, a portion of the bottom wall 21b of the fluid container 2 forms a peripheral cylindrical portion 4 that protrudes from the general bottom wall 21g, which is the other portion of the bottom wall 21b. The peripheral cylindrical portion 4 protrudes from the outside to the inside of the containment space 20. The peripheral cylindrical portion 4 is bottomed, and the bottom wall 4b of the peripheral cylindrical portion 4 is located on the inside side of the containment space 20.

[0080] A through-hole-shaped drain hole 3 is provided in the bottom wall 4b of the peripheral cylindrical portion 4. As shown in Figure 3, the drain hole 3 has a main hole portion 30 and a through hole portion 31. The main hole portion 30 and the through hole portion 31 each have a substantially circular radial cross-section.

[0081] The through-hole 31 is located radially outward from the main hole 30 and is in contact with a part of the main hole 30 in the circumferential direction. The radial length of the through-hole 31 is smaller than the radial length of the main hole 30, and approximately 20% of the circumferential length of the main hole 30 (approximately 70° in terms of angle) is in contact with the through-hole 31. The radial length of the main hole 30 is slightly larger than the radial length of the core, and the radial length of the through-hole 31 is slightly smaller than the radial length of the main hole 30.

[0082] As shown in Figures 8, 9, and 11, the bottom wall 4b is slightly curved in the direction from the outside to the inside of the containment space 20. Therefore, the drain hole 3 formed in the bottom wall 4b is also slightly curved in the direction from the outside to the inside of the containment space 20.

[0083] The peripheral edge of the main hole 30 in the bottom wall 4b shown in Figure 3 is the hole peripheral edge 45 that screws into the threaded rib portion 53 of the drain plug 5. As shown in Figure 11, the hole peripheral edge 45 has a tapered shape that becomes thinner towards the drain hole 3.

[0084] As shown in Figure 8, the bottom wall 4b is slightly curved in the direction from the outside to the inside of the storage space 20, and the drain hole 3 formed in the bottom wall 4b is also slightly curved in the direction from the outside to the inside of the storage space 20. Therefore, the periphery of the hole 45 is also slightly curved in the direction from the outside to the inside of the storage space 20. More specifically, the periphery of the hole 45 has a helical shape corresponding to the threaded rib portion 53.

[0085] Four window portions 46 are provided at the boundary between the peripheral wall and the bottom wall 4b of the peripheral cylindrical portion 4, allowing communication between the inside and outside of the peripheral cylindrical portion 4. Each window portion 46 is arranged substantially evenly along the circumferential direction of the peripheral cylindrical portion 4.

[0086] The internal space of the peripheral cylindrical portion 4 is composed of a general portion 41 located on the inside of the housing space 20 and a flange housing portion 42 located on the outside of the housing space 20. The radial cross-sections of the general portion 41 and the flange housing portion 42 are generally circular.

[0087] As shown in Figures 3 and 11, the radial length of the flange housing portion 42 is greater than the radial length of the general portion 41, and the flange housing portion 42 and the general portion 41 are continuous in a stepped manner. Of the inner surfaces that demarcate the flange housing portion 42 in the peripheral cylindrical portion 4, the end face on the inner side of the housing space 20 is substantially flat. Hereinafter, this end face will be referred to as the regulating surface 44 as needed.

[0088] As shown in Figures 3 and 4, the peripheral edge of the flange housing portion 42 partially protrudes radially inward. The protruding portion of the flange housing portion 42 is referred to as the peripheral engagement portion 48.

[0089] The rear side of the peripheral engagement portion 48 in the clockwise direction is an upright surface extending radially from the flange housing portion 42. The front side of the peripheral engagement portion 48 in the clockwise direction is an inclined surface that slopes from the front side in the clockwise direction and radially outward from the flange housing portion 42 to the rear side in the clockwise direction and radially inward from the flange housing portion 42.

[0090] As shown in Figure 5, the drain plug 5 has a flange portion 51 and a threaded portion 50, of which the threaded portion 50 has a core portion 52 and a threaded rib portion 53.

[0091] The flange portion 51 is roughly disc-shaped, and the core portion 52 of the threaded portion 50 is roughly cylindrical in shape, extending axially from the approximate center of the flange portion 51.

[0092] A threaded rib portion 53 is integrally formed on the tip portion of the core portion 52. The tip portion of the core portion 52 protrudes slightly further forward than the tip portion of the threaded rib portion 53. The threaded rib portion 53 is roughly plate-shaped, projecting radially outward from the outer circumferential surface of the core portion 52, and extends spirally around the axis of the core portion 52. The radial length of the threaded rib portion 53 is approximately 60% of the radial length of the core portion 52.

[0093] The radial length of the flange portion 51 is greater than the radial length of the core portion 52 and the radial length of the threaded portion 50, which includes the core portion 52 and the threaded rib portion 53. Furthermore, as shown in Figures 5 and 6, the radial length of the outer portion of the flange 51 is greater than the radial length of the inner portion of the flange 51, i.e., the tip portion. The outer portion of the flange 51 is referred to as the outer flange portion 51o, and the tip portion of the flange 51 is referred to as the inner flange portion 51i.

[0094] The outer flange portion 51o and the inner flange portion 51i of the flange portion 51 are connected in a stepped manner. A ring-shaped groove portion 51g is provided in the inner flange portion 51i approximately in the axial center, recessing radially inward and opening radially outward. A sealing material 6, or O-ring, described later, is fitted into this groove portion 51g.

[0095] The outer surface of the outer flange portion 51o of the flange portion 51 is provided with an insertion opening 58 for a hex wrench and an insertion opening 59 for a flathead screwdriver. The socket 58 for the hex wrench is a recess that is recessed from the outer side of the outer flange portion 51o toward the tip, and its radial cross-section is approximately a regular hexagon. The slot 59 for the flathead screwdriver is a recess that extends from approximately the center of the bottom surface of the slot 58 for the hex wrench toward the tip, and its radial cross-section is roughly rectangular.

[0096] Furthermore, as shown in Figures 4 and 6, a portion of the outer circumference of the outer flange portion 51o has an uneven shape directed radially. The portion of the outer flange portion 51o that has this uneven shape is referred to as the flange-side engaging portion 55.

[0097] The forward portion of the flange-side engaging portion 55 in the clockwise direction is a recessed portion 55c that is recessed radially inward, and the rear portion of the flange-side engaging portion 55 in the clockwise direction is a convex portion 55p that protrudes radially outward.

[0098] The recess 55c has a shape complementary to the peripheral engagement portion 48. The surface located on the clockwise leading side of the recess 55c is an inclined surface that slopes from the clockwise leading side and radially outward of the flange portion 51 toward the clockwise rear side and radially inward of the flange portion 51. The surface located on the clockwise rear side of the recess 55c is an upright surface extending radially from the flange portion 51, and this surface can also be said to be the surface located on the clockwise leading side of the convex portion 55p. The recess 55c has a shape that is generally complementary to the peripheral engagement portion 48 of the flange-side engagement portion 55.

[0099] A sealing material 6, which is an O-ring, is fitted to the outer circumferential surface of the outer flange portion 51o of the flange portion 51, or more specifically, to the groove portion 51g provided in the outer flange portion 51o.

[0100] As previously described, the drain plug 5 and fluid container 2 in the drain plug structure 1 of Example 1 are injection molded.

[0101] The mold for injection molding the fluid container 2 can be divided into a mold surface for forming the internal space of the peripheral cylindrical portion 4 and a mold surface for forming the outer surface of the peripheral cylindrical portion 4. As shown by the thick lines in Figure 8, the parting lines can be located on the outer edge of the drain hole 3 and on the outer edge of each window portion 46.

[0102] The mold for forming the drain plug 5 can be divided into a portion for forming the threaded portion 50 of the drain plug 5 and a portion for forming the flange portion 51. Furthermore, the portion for forming the flange portion 51 can be divided into approximately two parts in the radial direction of the flange portion 51. As shown by the thick lines in Figure 7, the parting lines in the mold can be located at the boundary between the threaded portion 50 and the flange portion 51, on the outer circumferential surface of the threaded rib in the threaded portion 50, and on the outer circumferential surface of the flange portion 51.

[0103] The behavior of each part of the drain plug structure 1 of Example 1 when the drain hole 3 of the fluid container 2 is blocked by the drain plug 5 will be described below.

[0104] When the drain hole 3 is closed with the drain plug 5, if the drain plug 5 is placed against the drain hole 3 and inserted, first the core portion 52 of the drain plug 5 enters the main hole portion 30 of the drain hole 3. If the drain plug is further inserted into the drain hole 3 in this state, the tip of the threaded rib portion 53 of the drain plug 5 enters the through hole portion 31. At this time, the tip of the threaded rib portion 53 exposes the drain hole 3 from the outside to the inside of the housing space 20 (Figures 9 to 11).

[0105] In this state, when the drain plug 5 is rotated clockwise, the threaded rib portion 53 that has entered the through hole portion 31 engages with the peripheral edge portion 45 of the hole, causing the drain plug 5 to be pulled inward (Figures 12 to 14). Then, the amount of exposed threaded rib portion 53 on the inside of the containment space 20 gradually increases, and the threaded rib portion 53 passes through the drain hole 3 from the outside to the inside of the containment space 20 (Figures 15 to 17). As a result, the drain plug 5 closes the drain hole 3.

[0106] At this time, the space between the outer circumferential surface of the flange portion 51 of the drain plug 5 and the inner surface of the peripheral cylindrical portion 4 is sealed by the sealing material 6, thereby liquid-tightly closing the drain hole 3 inside the peripheral cylindrical portion 4.

[0107] At this time, the surface of the threaded rib portion 53 on the flange portion 51 side, that is, the contact surface 53c of the threaded rib portion 53, and the surface of the hole periphery portion 45 on the inner side of the housing space 20, that is, the contact surface 45c of the hole periphery portion 45, are in contact.

[0108] As described above, the hole periphery 45 curves spirally in accordance with the contact surface 53c of the threaded rib portion 53, so that the contact surface 53c of the threaded rib portion 53 and the contact surface 45c of the hole periphery 45 are in surface contact.

[0109] Furthermore, the periphery of the hole 45 has a spirally curved shape and functions as a leaf spring, so that the contact surface 53c of the threaded rib 53 and the contact surface 45c of the periphery of the hole 45 are pressed against each other. This prevents the drain plug 5 from rotating in the reverse direction, so that the drain plug 5 is stably held by the periphery of the hole 45 and the drain hole 3 is stably closed.

[0110] When the drain plug 5 is rotated further clockwise, as shown in Figure 19, the peripheral-side engaging portion 48 of the fluid container 2 fits into the recess 55c of the flange-side engaging portion 55 of the drain plug 5. At this time, because the peripheral engagement portion 48 is located clockwise ahead of the convex portion 55p of the flange-side engagement portion 55, the flange-side engagement portion 55 and the peripheral engagement portion 48 engage, thereby preventing the clockwise and counterclockwise rotation of the drain plug 5.

[0111] This engagement mechanism functions as a secondary anti-rotation mechanism that prevents the drain plug 5 from rotating in the reverse direction, i.e., counterclockwise, so that the drain plug 5 is held more stably at the periphery of the hole 45 and the drain hole 3 is more stably closed.

[0112] At this time, the threaded portion 50 and the inner flange portion 51i of the flange portion 51 of the drain plug 5 extend further into the housing space than the general portion 41 of the peripheral cylindrical portion 4 and the general portion 41. The outer flange portion 51o of the flange portion 51 then enters the flange housing portion 42. Therefore, in the closed state, the flange portion 51 is positioned inward from the outer end of the flange housing portion 42, and at this time, the drain plug 5 is placed in an environment where it is less susceptible to external forces.

[0113] Furthermore, at this time, the tip side of the flange portion 51 faces the restricting surface 44. Because the restricting surface 44 functions as a stopper, the flange portion 51 cannot change position beyond the restricting surface 44 into the interior of the housing space, and further positional changes of the drain plug 5 facing inward into the housing space are restricted.

[0114] In the drain plug structure 1 of Embodiment 1, the threaded rib portion 53 screws into the hole periphery portion 45 and passes through the drain hole 3 to the inside of the housing space 20, and the contact surface 53c of the threaded rib portion 53 and the contact surface 45c of the hole periphery portion 45 come into contact, thereby closing the drain hole 3 with the drain plug 5. Therefore, in the drain plug structure 1 of Example 1, the structure near the drain hole 3 that screws into the drain plug 5 in the fluid container 2 can be made simple, and the fluid container 2 can be easily manufactured.

[0115] In the drain plug structure 1 of Embodiment 1, the contact surface 53c of the threaded rib portion 53 and the contact surface 45c of the hole periphery portion 45 come into contact, thereby inhibiting the reverse rotation of the drain plug 5 and preventing the drain plug 5 from coming out of the drain hole 3. Therefore, the drain plug structure 1 of Example 1 does not require a cantilever beam structure to prevent the reverse rotation of the drain plug 5, as is the case with the technology described in Patent Document 1, for example, and thus offers superior durability.

[0116] (Example 2) The drain plug structure of Example 2 is substantially the same as the drain plug structure of Example 1, except for the shape of the drain plug. Figure 21 is a schematic diagram illustrating the drain plug in the drain plug structure of Example 2. Figures 22 and 23 are schematic diagrams illustrating how the drain hole of the fluid container is blocked by the drain plug in the drain plug structure of Example 2. Figure 22 shows the drain plug structure of Example 2 in a semi-blocked state and in the initial stages of the blocking operation, while Figure 23 shows the drain plug structure of Example 2 in a blocked state. The following describes the drain plug structure of Example 2, focusing on the differences from the drain plug structure of Example 1.

[0117] As shown in Figure 21, the drain plug 5 in the drain plug structure 1 of Example 2 has a flange portion 51 and a threaded portion 50, and is substantially the same as the drain plug 5 in the drain plug structure 1 of Example 1, except that the core portion 52 of the threaded portion 50 protrudes significantly further toward the tip than the threaded rib portion 53.

[0118] The portion of the core 52 that protrudes further towards the tip than the tip of the threaded rib portion 53 is referred to as the assembly guide portion 52G. In the drain plug 5 of the drain plug structure 1 of Embodiment 2, the axial length of the assembly guide portion 52G is about 40% of the total axial length of the core 52, and its actual size is about 3 mm.

[0119] In the drain plug structure 1 of Example 2, since the core portion 52 of the drain plug 5 has an assembly guide portion 52G, as shown in Figure 22, in a semi-closed state and in the initial stages of the closing operation, the assembly guide portion 52G passes through the main hole portion 30 of the drain hole 3 and is largely exposed to the inside of the containment space 20 in the fluid container 2.

[0120] By performing the blocking operation in this state, the drain plug 5 is guided to be assembled at the correct assembly angle to the drain hole 3 of the fluid container 2, and is assembled in the correct position to the drain hole 3 as shown in Figure 23.

[0121] In the drain plug structure 1 of this embodiment 2, similar to the drain plug structure 1 of embodiment 1, the structure of the fluid container 2 near the drain hole 3 that screws into the drain plug 5 can be made simple, and the fluid container 2 can be easily manufactured.

[0122] Furthermore, the drain plug structure 1 of Example 2 also has superior durability because it does not require a cantilever structure to prevent the reverse rotation of the drain plug 5.

[0123] Although the present invention has been described above, the present invention is not limited to the embodiments described above, and it is possible to implement the invention by appropriately extracting and combining the elements described in the embodiments, and to make various modifications without departing from the spirit of the present invention. Furthermore, the specification of this invention discloses not only the reference relationships of each claim as initially filed, but also a technical concept that appropriately combines the matters described in each claim. [Explanation of symbols]

[0124] 1: Drain plug structure 2: Fluid container 20: Containment space 21: Wall part 3: Drain hole 30: Main hole 31: Passing hole 4: Peripheral cylindrical part 4b: Bottom wall of the peripheral cylindrical section 41:General section 42: Flange housing 48: Peripheral engagement portion 45: Periphery of the hole 45c: The outer surface (contact surface) of the containment space at the edge of the hole. 5: Drain plug 51: Flange section 52: Core 53: Threaded rib section 53c: The flange-side surface (contact surface) of the threaded rib section. 55: Flange-side engagement portion

Claims

1. A fluid container having a wall portion that partitions the containment space, a drain hole formed through the wall portion, and a drain plug that closes the drain hole, The drain hole has a main hole portion and a through hole portion located radially outside the main hole portion and communicating with a part of the main hole portion in the circumferential direction. The drain plug has a flange portion, a core portion integrally formed with the flange portion and extending from the flange portion, and a threaded rib portion integrally formed with the tip side of the core portion and extending spirally around the axis of the core portion. When the drain plug blocks the drain hole, The core portion enters the main hole portion, The threaded rib portion that enters the through hole portion engages with the hole periphery portion of the wall portion located at the periphery of the main hole portion, and passes through the drain hole from the outside to the inside of the containment space. In the blocked state in which the drain plug blocks the drain hole, A drain plug structure in which the flange-side surface of the threaded rib portion and the outer surface of the housing space on the periphery of the hole come into contact.

2. The periphery of the hole is spiral-shaped, corresponding to the threaded rib portion. The drain plug structure according to claim 1, wherein, in the closed state, the outer surface of the housing space at the periphery of the hole and the flange-side surface of the threaded rib are in surface contact.

3. The drain plug structure according to claim 1 or claim 2, wherein the threaded rib portion is formed within a range not exceeding 360° around the axis of the core portion.

4. The fluid container has a cylindrical peripheral portion provided on the wall that protrudes from the outside to the inside of the containment space, The bottom wall of the peripheral cylindrical portion is provided with the drain hole and the periphery of the hole. The internal space of the peripheral cylindrical portion has a general portion located on the inside side of the housing space and a flange housing portion located on the outside side of the housing space, which has a larger diameter than the general portion and is stepped and continuous with the general portion. In the closed state, the flange portion is recessed inward from the outer end of the flange housing portion, as described in claim 1 or 2.

5. The peripheral cylindrical portion has a peripheral engagement portion that protrudes toward the flange housing portion at the peripheral edge of the flange housing portion, The drain plug structure according to claim 4, wherein the flange portion has a flange-side engaging portion on its outer edge that engages with the peripheral-side engaging portion in the closed state.

6. A drain plug for closing a drain hole in a fluid container having a wall portion that partitions a storage space and a drain hole formed through the wall portion, It has a flange portion, a core portion integrally formed with the flange portion and extending from the flange portion, and a threaded rib portion integrally formed on the tip side of the core portion and extending spirally around the axis of the core portion, When closing the drain hole, The core portion enters the main hole portion of the drain hole, The threaded rib portion, which enters a through hole in the drain hole located radially outside the main hole and connected to a part of the circumferential direction of the main hole, screws into the hole periphery portion of the wall portion located at the periphery of the main hole, and passes through the drain hole from the outside to the inside of the containment space. In the blocked state in which the drain plug blocks the drain hole, A drain plug in which the flange-side surface of the threaded rib portion abuts against the outer surface of the housing space at the periphery of the hole.

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