Oil pan, engine and working machine

Abstract

The utility model relates to an oil pan, an engine and an operation machine. The oil pan includes an oil pan body and a plug. The oil pan body comprises an oil drainage hole formed in the pan wall of the oil pan body in a penetrating mode. The plug is configured to detachably plug the oil drain hole. The plug includes a plug section made of an elastic material and capable of being squeezed into the oil drain hole by elastic deformation. The inner circumferential surface of the oil drainage hole is connected with the inner side surface of the shell wall through an edge line. Under the action of the elastic restoring force, the filling part section forms line contact sealing with the edge line and forms surface contact sealing with the inner circumferential surface of the oil drainage hole. According to the oil drainage structure of the oil pan, threads do not need to be machined on the oil drainage hole and the plug, it can be ensured that the plug can well seal the oil drainage hole without using a sealing ring, assembly and disassembly are easy and convenient, and the machining, manufacturing, disassembly, assembly and maintenance cost is low.

Description

Technical Field

[0001] This utility model relates to the technical field of engine components, and more specifically to an oil pan with an improved oil draining structure that can be used, especially in engines for work machinery. Background Technology

[0002] The oil pan is a crucial component of the engine, located at the very bottom and typically bolted to the engine block. Its primary function is to store engine oil and provide it to the engine's lubrication system, ensuring proper lubrication of all moving parts and reducing wear. The oil in the pan comes into contact with air and also dissipates some of the heat generated by the engine, helping to maintain the oil at the appropriate operating temperature. Furthermore, the oil pan allows metal shavings, dust, and other impurities carried by the oil during circulation to settle to the bottom, preventing them from re-entering the lubrication system and affecting normal engine operation.

[0003] Oil pans typically have a drain hole at the bottom for easy oil changes. Current oil pan drain holes are usually sealed by tightening an O-ring onto the sealing surface of the drain hole using a metal plug. This sealing structure and method requires high precision in the roughness and flatness of the sealing surface and involves cumbersome assembly and disassembly operations, such as requiring a specialized torque wrench to tighten and loosen the metal plug. If the tightening torque decreases, the O-ring may not be tightened properly, resulting in a poor seal. Since engine oil fills the sealing surface around the O-ring, the decreased tightening force combined with engine vibration will inevitably cause oil leakage, requiring retightening with tools. Furthermore, if the roundness of the O-ring varies significantly at different cross-sections, leakage is also likely to occur. Utility Model Content

[0004] The purpose of this invention is to solve at least one of the above-mentioned problems and / or other defects in the prior art.

[0005] To achieve the above objectives, one aspect of the present invention provides an oil pan, the oil pan including an oil pan body and a plug. The oil pan body includes an oil drain hole perforated in its wall. The plug is configured to removably seal the oil drain hole. The plug includes a filling section made of an elastic material that can be squeezed into the oil drain hole by elastic deformation. The inner circumferential surface of the oil drain hole is connected to the inner surface of the oil pan wall by an edge line. Under the action of its elastic restoring force, the filling section forms a line contact seal with the edge line and a surface contact seal with the inner circumferential surface of the oil drain hole.

[0006] According to one embodiment of the present invention, the inner circumferential surface of the oil drain hole is perpendicular to the inner surface of the shell wall.

[0007] According to one embodiment of the present invention, the inner peripheral surface of the oil drain hole is connected to the outer surface of the shell wall by a first conical transition surface that gradually expands outward toward the outer side of the shell wall.

[0008] According to one embodiment of the present invention, the end of the filling section that is to be inserted into the oil drain hole from the outside of the shell wall is provided with a tapered oblique surface at its end edge.

[0009] According to one embodiment of the present invention, the plug further includes an extension section connected to the filling section and having a diameter larger than the filling section, wherein the end face of the extension section facing the filling section forms an annular stepped surface that can abut against the shell wall surrounding the drain hole.

[0010] According to one embodiment of the present invention, the annular stepped surface and the outer peripheral surface of the filling section are connected by a second conical transition surface. The second conical transition surface and the first conical transition surface have matching shapes so as to form a surface contact seal when the annular stepped surface abuts against the shell wall around the oil drain hole.

[0011] According to one embodiment of the present invention, a central hole extending along the length direction is provided in the filling section.

[0012] According to one embodiment of the present invention, the oil pan further includes a cap that is detachably fixed to the pan wall. When the plug blocks the drain hole, the cap can abut against the plug from the outside of the pan wall to prevent the plug from coming out of the drain hole.

[0013] According to one embodiment of the present invention, the shell wall includes a peripheral wall portion extending outward from the drain hole, the peripheral wall portion defining a receiving space that at least partially accommodates the plug and the cap, a groove is provided in the inner peripheral surface of the peripheral wall portion, the cap includes a cover portion that can be abutted by the plug and two locking feet extending outward from the cover portion and facing each other in the diametrical direction, each locking foot having a hook portion extending radially outward at its end, the two locking feet being able to spring back to each other to enter the receiving space and spring back away from each other to engage their respective hook portions in the groove.

[0014] According to one embodiment of the present invention, the groove includes two opposing groove segments in the diametrical direction of the peripheral wall portion, each groove segment being configured to receive a hook portion of a corresponding latch of the cap and prevent the latch from rotating circumferentially.

[0015] According to one embodiment of the present invention, a column is provided on the side of the cover where the two locking feet are provided, and the column is embedded in the plug to assemble the plug and the cap into one piece.

[0016] Another aspect of this invention provides an engine that includes an oil pan according to any of the preceding claims.

[0017] Another aspect of this utility model provides a working machine that includes the engine described above.

[0018] The oil pan of this invention features an improved drain structure, in which a plug made of elastic material replaces the existing metal screw plug for sealing the drain hole. The plug can be directly inserted into the drain hole through its elastic deformation. The inserted portion immediately springs open and bulges under the action of elastic restoring force, forming a line-contact primary seal with the inner edge of the drain hole and a surface-contact secondary seal with the inner circumferential surface of the drain hole, achieving good sealing performance without the need for a sealing ring. This sealing method of the drain structure does not have strict requirements on the roundness and roughness of the sealing surfaces, and eliminates the need to machine threads on the drain hole and the plug. Furthermore, it avoids the need for large local casting thicknesses for thread machining, improving the casting performance of the structure around the drain hole and reducing the risk of poor sealing due to casting porosity and exposed casting porosity after thread machining. In addition, this drain structure is easy to assemble and disassemble, requiring no special tools; the plug can be manually inserted and removed relative to the drain hole. In summary, the oil draining structure of the oil pan according to this utility model is more convenient and less costly in terms of processing, manufacturing, disassembly and maintenance compared with the prior art. Attached Figure Description

[0019] The features and advantages of this utility model will become clear from the following detailed description provided with reference to the accompanying drawings. It should be understood that the following drawings are merely schematic and not necessarily drawn to scale, and therefore should not be considered as limitations on this utility model, wherein:

[0020] Figure 1 A perspective view of an oil pan according to an embodiment of the present invention is shown.

[0021] Figure 2 Show Figure 1 The top view of the oil pan shown.

[0022] Figure 3 Show Figure 1 A magnified view of the oil drain structure (point A) in the oil pan shown.

[0023] Figure 4 Show Figure 3 An exploded view of the oil-discharging structure is shown.

[0024] Figure 5 Show Figure 4A three-dimensional view of the plug and cap in the oil drain structure shown.

[0025] Figure 6 Show Figure 2 The image shows a partial cross-sectional view of the oil pan along line BB.

[0026] Figure 7 Show Figure 1 A perspective view of an exemplary configuration of the drain hole in the oil pan.

[0027] Figure 8 Show Figure 7 The oil drain hole shown is a partial cross-sectional view from another angle.

[0028] Figure 9 Show Figure 1 A perspective view of another exemplary configuration of the drain hole in the oil pan. Detailed Implementation

[0029] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, numerous specific details are set forth to enable those skilled in the art to more fully understand and implement the present invention. However, it will be apparent to those skilled in the art that implementations of the present invention may not include some of these specific details. Furthermore, it should be understood that the present invention is not limited to the specific embodiments described. Rather, the present invention can be conceived to be implemented with any combination of the features and elements described below, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages are for illustrative purposes only and should not be construed as elements or limitations of the claims unless expressly set forth in the claims.

[0030] The terms "first" and "second" are used below to describe the elements of this application. These terms are used only to distinguish the individual elements and not to limit the nature, order, or number of these elements. The terms "comprising" and "having" are used to indicate an open-ended inclusion and mean that there may be additional elements / components besides those listed.

[0031] Figures 1 to 8 An oil pan according to one embodiment of the present invention is shown. Figures 1 to 3 As shown, the oil pan according to this embodiment may include an oil pan body 1, a plug 2, and a cap 3.

[0032] The oil pan body 1 may include multiple shell walls 13 (e.g., bottom wall, side wall, etc.), which may enclose an oil reservoir 11 with an opening at the top. The oil pan body 1 may also include an oil drain hole 12 penetrating one of the shell walls 13 as part of the oil drain structure of the oil pan. In some embodiments, the oil drain hole 12 is located near the bottom edge of one of the side walls 13. In another embodiment, the oil drain hole 12 may also be located on the bottom wall of one of the shell walls 13. In the illustrated embodiment, the oil drain hole 12 is located on one side wall of the oil pan body 1, therefore the side wall will be specifically described as shell wall 13. A plug 2 may be disposed within the oil drain hole 12 of the shell wall 13 to seal the oil drain hole 12, and can be removed from the oil drain hole 12 when oil needs to be drained. In the illustrated embodiment, the portion of the shell wall 13 where the drain hole 12 is located may be recessed relative to the main body of the shell wall 13 toward the liquid storage cavity 11, thereby forming a recessed space that can be used to receive the plug 2, so as to prevent the plug 2 from protruding too much from the shell wall 13 when blocking the drain hole 12.

[0033] like Figure 4 and Figures 6 to 9 As shown, the oil drain structure of the oil pan according to this utility model is configured such that the inner circumferential surface 121 of the oil drain hole 12 (i.e., the circumferential surface of the shell wall 13 through which the oil drain hole 12 passes, surrounding and defining the oil drain hole 12); from Figure 8 (It can be seen more clearly) The inner surface of the shell wall 13 is connected (i.e., intersecting and connected) by the edge line 14. In this application, for the oil pan body 1 or its shell wall 13, the orientation pointing towards or facing the oil reservoir 11 is defined as "inner", while the orientation away from the oil reservoir 11 is defined as "outer". Thus, the inner surface of the shell wall 13 is the side of the shell wall 13 facing the oil reservoir 11, while the outer surface of the shell wall 13 is the other side of the shell wall 13 away from the oil reservoir 11 and opposite to its inner surface. In this application, the inner circumferential surface 121 of the drain hole is connected to the inner surface of the shell wall 13 by the edge line 14. This indicates that the junction between the inner circumferential surface 121 of the drain hole and the inner surface of the shell wall 13 is not a smooth transition by, for example, chamfering or rounding, but is formed by a sharp angle by the edge line 14. This is beneficial for forming a reliable seal between the plug 2 and the drain hole 12 (described in detail below).

[0034] The plug 2 may include a filling section 21, which is made of an elastic material (such as rubber) and can be squeezed into the drain hole 12 through elastic deformation. This means that the filling section 21 has an outer diameter larger than the inner diameter of the drain hole 12 in its normal state when not inserted into the drain hole 12. Due to the characteristics of its elastic material, the filling section 21, which is inserted into the drain hole 12 through compression deformation, will immediately rebound and bulge under the action of elastic restoring force, thereby forming a tight line contact with the edge line 14 between the inner peripheral surface 121 of the drain hole and the inner surface of the shell wall 13. This line contact involves a small contact area and a high contact pressure, thereby forming a reliable first seal (main seal) between the filling section 21 and the drain hole 21. Those skilled in the art will readily understand that, since the filling section 21 of the plug 2 will form line contact with the edge line 14, the extent or length to which the filling section 21 is inserted into the drain hole 12 towards the inner side of the shell wall 13 should exceed the inner surface of the shell wall 13 (from...). Figure 6 (This can be clearly seen in the image). On the other hand, the portion of the plug section 21 located in the drain hole 12 will also rebound and bulge under the action of elastic restoring force, pressing against and adhering to the inner circumferential surface of the drain hole 12, thereby forming a surface contact with the inner circumferential surface. This surface contact will form a second seal (auxiliary seal) between the plug section 21 and the drain hole 21, following the first seal of the above-mentioned line contact type. The combination of the above-mentioned line contact seal and surface contact seal allows the plug 2 to achieve good sealing of the drain hole 12 without using any sealing components (such as O-rings). The outer diameter of the plug section 21 and the elasticity and strength of its elastic material can be appropriately set so that the plug section 21 can undergo appropriate deformation in the drain hole 12 to ensure sufficient sealing, while not requiring too much effort when the plug section 21 is inserted into the drain hole 12 and pulled out of the drain hole.

[0035] In this invention, the inner circumferential surface 121 of the drain hole 12 connects with the inner surface of the shell wall 13 to form an edge line 14, i.e., a sharp angle. The size of this sharp angle is not particularly limited; it can be less than 90 degrees, equal to 90 degrees, or greater than 90 degrees, as long as the plugging portion 21 of the plug 2 can be inserted into the drain hole 12 and pulled out of the drain hole, and the sealing between the two is ensured by the aforementioned line contact seal and surface contact seal. However, preferably, as in the illustrated embodiment, the inner circumferential surface 121 of the drain hole 12 is perpendicular to the inner surface of the shell wall 13 (i.e., at a 90-degree angle relative to each other). This facilitates the easy processing of the drain hole 12 in the shell wall 13, and also achieves a good balance between facilitating the installation and removal of the plug 2 relative to the drain hole 12 and ensuring the sealing between the two.

[0036] like Figure 4 and Figure 6-8As shown, the inner circumferential surface 121 of the drain hole 12 and the outer surface of the shell wall 13 can be connected by a first conical transition surface 15. The first conical transition surface 15 gradually expands outward toward the outer side of the shell wall 13 (i.e., in the direction away from the oil reservoir 11), which facilitates the insertion of the plug section 21 of the plug 2 into the drain hole 12. The first conical transition surface 15 can be formed, for example, by rounding or chamfering the junction between the inner circumferential surface 121 of the drain hole 12 and the outer surface of the shell wall 13.

[0037] Optionally, such as Figure 5 and Figure 6 As shown, the end of the plug section 21 of the plug 2 that is to be inserted into the drain hole 12 from the outside of the shell wall 13 has a tapered bevel 22 at its end edge. The tapered bevel 22 tapers toward the drain hole 12, thereby facilitating the insertion of the plug section 21 into the drain hole 12, similar to the first tapered transition surface 15. The tapered bevel 22 can also be formed, for example, by rounding or chamfering the aforementioned end edge of the plug section 21.

[0038] like Figure 5 and 6 As shown, a central hole 26 extending along its length direction may be provided in the filling section 21 of the plug 2, which can be used as a space for displacing surrounding material so that the filling section 21 can be more easily squeezed and inserted into the drain hole 12.

[0039] Continue to refer to Figure 5 and Figure 6 As shown, the plug 2 may further include an extension section 23 connected to the filling section 21. The extension section 23 is gripped by hand to facilitate inserting and removing the filling section 21 of the plug 2 into the drain hole 12. The extension section 23 and the filling section 21 may be integrally formed from the same material or formed from different materials and then joined together. Optionally, as in the illustrated embodiment, the diameter of the extension section 23 is larger than the diameter of the filling section 21, thereby the extension section 23 has an end face facing the filling section 21, which is in the form of an annular stepped surface 24. After the filling section 21 of the plug 2 is inserted into the drain hole 12, the annular stepped surface 24 can abut against the shell wall 13 surrounding the drain hole 12 to prevent the plug 2 from being accidentally inserted too deeply and falling completely into the oil reservoir 11 of the oil pan.

[0040] In one embodiment, reference Figure 6As shown, the annular stepped surface 24 and the outer peripheral surface of the plug section 21 can be connected by the second conical transition surface 25. The second conical transition surface 25 and the first conical transition surface 15 can have shapes that roughly match each other, so that when the plug section 21 is inserted into the drain hole 12 and the annular stepped surface 24 abuts against the shell wall 13 around the drain hole, the first conical transition surface 15 and the second conical transition surface 25 can roughly fit together to form a surface contact. This surface contact can provide an additional third seal after the first and second seals, thereby further improving the sealing performance of the plug 2 relative to the drain hole 12.

[0041] Generally, the pressure inside the oil pan is low, typically fluctuating slightly around atmospheric pressure. Therefore, the clamping force exerted on the plug 2 when inserted into the drain hole 12 is sufficient to prevent the plug 2 from coming out of the drain hole. Nevertheless, to prevent the plug from loosening due to engine vibration or other factors, the oil pan according to this embodiment may also include a cap 3. (See reference...) Figures 1 to 6 As shown, with the plug 2 blocking the drain hole 12, the cap 3 can be detachably fixed to the shell wall 13, and can abut against the plug 2 from the outside of the shell wall 13 (see especially). Figure 6 To prevent plug 2 from coming out of drain hole 12.

[0042] To secure the cap 3 to the shell wall 13, the aforementioned recessed space formed by the portion of the shell wall 13 where the oil drain hole 12 is located relative to the main body of the shell wall 13 can be utilized. More specifically, as from... Figure 6 and 8 As can be clearly seen, the shell wall 13 may include a peripheral wall portion 16 extending outward from the drain hole 12. The peripheral wall portion 16 defines a receiving space, namely the aforementioned recessed space, for at least partially accommodating the plug 2 and the cap 3. A groove 17 may be provided in the inner peripheral surface of the peripheral wall portion 16, and the cap 3 can be locked into the groove 17, thereby securing it to the shell wall 13.

[0043] Combination Figures 3 to 6As shown, in one specific embodiment, the cap 3 may include a cap portion 31 and two latches 32. The cap portion 31 may be generally plate-shaped, for example, for the plug 2 to abut against one side of it. The two latches 32 extend from this side and are opposite each other in the diametrical direction. For example, each latch 32 may be arc-shaped. Each latch 32 has a hook portion 33 extending radially outward at its end opposite to the cap portion 31. In the normal state, the distance between the radial outer edges of the two hook portions 33 is greater than the diameter of the receiving space formed by the peripheral wall portion 16 at the outermost part of the shell wall, so that the two hook portions 33 cannot enter the receiving space. The material and / or length of the two latches 32 are set such that they are elastic enough to spring back and move closer to each other under the action of a compressive force. In the close state, the distance between the radial outer edges of the two hook portions 33 can be reduced until the two hook portions 33 can enter the aforementioned receiving space and reach the position of the groove 17 on the peripheral wall portion 16. After the external force of compression on the two locking feet 32 ​​is removed, they will spring back away from each other, causing their respective hooks 33 to engage in the grooves 17. Thus, the two locking feet 32 ​​and the entire cap 3 cannot be removed from the grooves 17, that is, they are fixed to the shell wall 13.

[0044] exist Figure 7 and 8 In the illustrated embodiment, the groove 17 is a closed annular groove surrounding the peripheral wall portion 16 in the circumferential direction, which can be formed, for example, in the inner circumferential surface of the peripheral wall portion 16 by machining. To facilitate the machining of this closed annular groove, a tool inlet / outlet groove 4 can be provided at the outermost end of the peripheral wall portion 16 opposite to the drain hole 12. In particular, two tool inlet / outlet grooves 4 can be provided opposite each other in the diametrical direction for the machining tool to enter and exit the aforementioned receiving space to machine the groove 17. The tool inlet / outlet groove 4 can be formed directly on the peripheral wall portion 16 of the shell wall 13 by casting during the manufacturing of the oil pan body 1.

[0045] exist Figure 9 Another example of the groove 17 is shown. In this example, the groove 17 is not a closed annular groove, but may include two separate groove segments 171. These two groove segments 171 can be opposed in the diametrical direction of the peripheral wall portion 16, thereby corresponding one-to-one with the positions of the two retaining feet 32 ​​and their hooks 33, so as to receive the hooks 33 of the corresponding retaining feet 32 ​​to prevent the retaining feet 32 ​​from rotating circumferentially, thus ensuring the secure installation of the cap 3 on the shell wall 13. In this example, the groove segments 171 can be formed directly on the peripheral wall portion 16, for example, by casting. Since the groove 17 or groove segments 171 are not formed by machining in this example, it is not necessary to form the aforementioned feed / retract groove on the peripheral wall portion 16.

[0046] In the illustrated embodiment, the peripheral wall portion 16 is formed by recessing inward from the main body portion of the shell wall 13. However, the present invention is not limited thereto. In other embodiments, the peripheral wall portion 16 may also be formed by extending outward from the main body portion of the shell wall 13 around the oil drain hole 12, in which case the oil drain hole 12 is directly formed in the main body portion of the shell wall 13.

[0047] Optionally, the side of the cap 31 where the two latches 32 extend can also be provided with a post, which can be embedded in the plug 2, so that the cap 3 and the plug 2 are assembled as one unit, so that the cap 3 can be fixed to the shell wall 13 at the same time as the plug 2 is inserted into the drain hole 12.

[0048] Industrial applicability

[0049] The oil pan according to this invention is applicable to various types of engines, especially engines used in construction machinery, such as diesel engines. Applicable construction machinery includes, for example, excavators, loaders, and other types of machines equipped with engines.

[0050] The following is based on Figures 1 to 9 The illustrated embodiment serves as an example to illustrate the assembly and disassembly process of the oil draining structure of the oil pan according to this utility model.

[0051] During assembly, first align the filling section 21 of the plug 2 with the drain hole 12 in the shell wall 13, and while rotating the extension section 23 of the plug 2, push the filling section 21 into the drain hole 12 towards the inside of the shell wall until the annular stepped surface 24 on the plug 2 abuts against the shell wall 13. Then, pinch the two locking feet 32 ​​of the cap 3 to deform them closer together, and push the locking feet 32 ​​into the receiving space formed by the peripheral wall 16. Then release, so that the two locking feet 32 ​​spring apart and their respective hooks 33 engage with the grooves 17 in the peripheral wall 16. At this time, the cap 3's cover 31 can also abut against the extension section 23 of the plug 2. Thus, the assembly operation of the drain structure is completed.

[0052] When it is necessary to disassemble the oil draining structure to drain the oil, pinch the two locking feet 32 ​​together forcefully to deform them until the hook 33 of each locking foot 32 comes out of the groove 17, and then remove the cap 3 outwards towards the outer side of the shell wall. Next, grasp the extension section 23 of the plug 2 and pull the plug 2 out of the oil drain hole 12 while rotating it, thus completing the disassembly of the oil draining structure.

[0053] In the oil drain structure of the oil pan according to this utility model, a plug 2 made of elastic material is used to replace the existing metal screw plug to seal the oil drain hole 12. The plug 2 can be directly squeezed into the oil drain hole 12 through its elastic deformation. The inserted filling section 21 will immediately spring open and bulge under the action of elastic restoring force, thereby forming a line contact type main seal with the inner edge line 14 of the oil drain hole 12 and a surface contact type auxiliary seal with the inner circumferential surface 121 of the oil drain hole, achieving good sealing performance without the need for a sealing ring. This sealing method of the oil drain structure does not have strict requirements for the roundness and roughness of the sealing surface, and there is no need to machine threads on the oil drain hole 12 and the plug 2. It also eliminates the need for a large local casting thickness to machine threads, improving the casting performance of the structure around the oil drain hole, thereby reducing the risk of poor sealing caused by casting porosity and casting porosity exposed after thread machining. In addition, this oil drain structure is easy to assemble and disassemble, without the need for special tools. The plug 2 can be manually inserted and pulled out relative to the oil drain hole 12. In summary, the oil draining structure of the oil pan according to this utility model is more convenient and less costly in terms of processing, manufacturing, disassembly and maintenance compared with the prior art.

[0054] Various modifications and variations can be made to the embodiments disclosed above without departing from the scope or spirit of this invention. Other embodiments of this invention will be apparent to those skilled in the art based on the practice of this invention disclosed in this specification. This specification and the examples disclosed herein should be considered illustrative only, and the true scope of this invention is defined by the appended claims and their equivalents.

Claims

1. An oil pan, comprising: An oil pan body (1), the oil pan body including an oil drain hole (12) penetrating its shell wall (13); and Plug (2), the plug being configured to removably seal the drain hole, The oil pan is characterized in that... The plug (2) includes a filling section (21) made of elastic material that can be squeezed into the drain hole by elastic deformation. The inner circumferential surface (121) of the drain hole is connected to the inner side surface of the shell wall (13) by an edge line (14). Under the action of its elastic restoring force, the filling section forms a line contact seal with the edge line and a surface contact seal with the inner circumferential surface of the drain hole.

2. The oil pan according to claim 1, characterized in that, The inner circumferential surface (121) of the oil drain hole (12) is perpendicular to the inner surface of the shell wall (13).

3. The oil pan according to claim 2, characterized in that, The inner circumferential surface (121) of the drain hole (12) is connected to the outer surface of the shell wall (13) by a first conical transition surface (15) that gradually expands outward toward the outer side of the shell wall.

4. The oil pan according to claim 3, characterized in that, The end of the plugging section (21) that is to be inserted into the drain hole (12) from the outside of the shell wall (13) has a tapered bevel (22) at its end edge.

5. The oil pan according to claim 3, characterized in that, The plug (2) further includes an extension section (23) connected to the plug section (21) and having a larger diameter than the plug section. The end face of the extension section facing the plug section forms an annular stepped surface (24) that can abut against the shell wall (13) surrounding the drain hole (12).

6. The oil pan according to claim 5, characterized in that, The annular stepped surface (24) is connected to the outer peripheral surface of the filling section (21) by a second conical transition surface (25), the second conical transition surface and the first conical transition surface (15) having matching shapes to form a surface contact seal when the annular stepped surface abuts against the shell wall (13) around the drain hole.

7. The oil pan according to any one of claims 1 to 6, characterized in that, A central hole (26) extending along its length is provided in the filling section (21).

8. The oil pan according to any one of claims 1 to 6, characterized in that, The oil pan also includes a cap (3) that is detachably fixed to the shell wall (13). When the plug (2) blocks the drain hole (12), the cap can abut against the plug from the outside of the shell wall (13) to prevent the plug from coming out of the drain hole.

9. The oil pan according to claim 8, characterized in that, The shell wall (13) includes a peripheral wall portion (16) extending outward from the drain hole (12) of the shell wall, the peripheral wall portion defining a receiving space that at least partially accommodates the plug (2) and the cap (3), a groove (17) is provided in the inner peripheral surface of the peripheral wall portion, the cap (3) includes a cover portion (31) that can be abutted by the plug (2) and two latches (32) that extend outward from the cover portion and are opposed in the diametrical direction, each latch having a hook portion (33) extending radially outward at its end, the two latches being able to spring back to each other to enter the receiving space and spring back away from each other to engage their respective hook portions in the groove.

10. The oil pan according to claim 9, characterized in that, The groove (17) includes two opposing groove segments (171) in the diametrical direction of the peripheral wall portion (16), each groove segment being configured to receive a hook (33) of a corresponding latch (32) of the cap (3) and prevent the latch from rotating circumferentially.

11. The oil pan according to claim 9, characterized in that, The cover (31) has a post on the side where the two clips (32) are located. The post is embedded in the plug (2) to assemble the plug and the cap into one piece.

12. An engine, characterized in that... Includes the oil pan according to any one of claims 1 to 11.

13. A type of operating machinery, characterized in that... Including the engine according to claim 12.

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