Bushing press-fitting structure of oil pan

Abstract

The utility model relates to the technical field of automobile engine production equipment, and discloses a bushing press-fitting structure of an oil pan, which comprises a rack, a positioning plate arranged on the rack, a plurality of supporting seats and a pressing mechanism which are arranged on the positioning plate, and a press-fitting mechanism arranged on the rack, the supporting seat is used for supporting an oil pan; the pressing mechanism is used for pressing the oil pan on the positioning plate; and the press-fitting mechanism is used for press-fitting the bushing into a mounting hole of the oil pan. By means of the structure, the accurate position of the oil pan in the press-fitting process is guaranteed, an accurate reference can be provided for press-fitting of the lining, it is guaranteed that the lining can be accurately pressed into the corresponding installation hole, the matching accuracy of the lining and the installation hole is improved, and the installation problem caused by position deviation is reduced.

Description

Technical Field

[0001] This utility model relates to the technical field of automobile engine production equipment, and in particular to a bushing press-fit structure for an oil pan. Background Technology

[0002] In the manufacturing and assembly of automobile engines, the oil pan is a critical component. Its main function is to store engine oil and provide a stable oil supply to the engine lubrication system. To ensure the stability of the oil pan during engine operation, reduce vibration and noise transmission, prevent wear, and guarantee good sealing performance, bushings are usually installed at the connection points between the oil pan and the engine or other related components.

[0003] Traditional bushing installation methods present numerous problems in actual production. In the large-scale production environment of automobile manufacturing, a large number of bushings need to be accurately installed into the mounting holes of the oil pan. Previous manual installation methods were inefficient and struggled to guarantee the accuracy of each bushing's placement. Because the bushings need to fit tightly into the oil pan's mounting holes, manual installation can lead to uneven force application, causing the bushings to become misaligned and affecting their subsequent performance. For example, it may result in uneven stress on the bushing during use, accelerating wear, and even potentially affecting the oil pan's sealing performance, leading to oil leaks.

[0004] Furthermore, with the development of the automotive industry, the requirements for the quality and assembly precision of engine components are becoming increasingly stringent. While some existing simple tooling-assisted installation methods improve installation efficiency to some extent, they still cannot meet the demands of high-precision installation. These tooling methods often fail to precisely control key parameters such as bushing insertion depth and perpendicularity, resulting in inconsistent installation quality. In addition, in large-scale production, the combination of manual operation and simple tooling is labor-intensive, detrimental to improving production efficiency and reducing production costs, and makes it difficult to guarantee product quality consistency. This negatively impacts the overall stability and reliability of automotive engine performance.

[0005] Therefore, there is an urgent need for a specialized device that can efficiently and accurately press bushings into the oil pan mounting holes to meet the high-quality, high-precision, and high-efficiency production requirements of modern automotive engine manufacturing. Utility Model Content

[0006] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a bushing press-fit structure for an oil pan, which aims to press the bushing into the mounting hole of the oil pan.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A bushing press-fit structure for an oil pan includes a frame, a positioning plate mounted on the frame, a plurality of support seats and a pressing mechanism mounted on the positioning plate, and a press-fit mechanism mounted on the frame; the support seats are used to support the oil pan; the pressing mechanism is used to press the oil pan onto the positioning plate; and the press-fit mechanism is used to press the bushing into the mounting hole of the oil pan.

[0009] The oil pan bushing press-fit structure includes a press-fit mechanism comprising a mounting bracket fixed to the frame, a drive cylinder with its cylinder body mounted on the mounting bracket and its output end facing the oil pan mounting hole, a press head connected to the output end of the drive cylinder, and a centering core disposed at the end of the press head; the centering core is used for inserting the bushing; the drive cylinder is used to drive the press head and the centering core to reciprocate along the axial direction of the oil pan mounting hole.

[0010] The bushing press-fit structure of the oil pan includes a fixing plate between the output end of the drive cylinder and the pressure head, and a pressure sensor between the pressure head and the fixing plate.

[0011] The oil pan bushing press-fit structure includes a mounting bracket that has two or more guide sleeves fixedly connected to it, the guide sleeves being located beside the drive cylinder; a guide rod is also slidably disposed in the guide sleeve, the connecting end of the guide rod being fixedly connected to the side wall of the fixing plate.

[0012] The bushing press-fit structure of the oil pan, wherein the free end of the guide rod is also provided with a stroke sensor pressure plate.

[0013] The bushing press-fit structure of the oil pan includes a first limiting plate and a second limiting plate on the mounting bracket. The first limiting plate and the second limiting plate extend along the length direction of the mounting bracket, and both the first limiting plate and the second limiting plate are provided with clearance holes. The size of the clearance holes is larger than the outer diameter of the pressure head.

[0014] The bushing press-fit structure of the oil pan, wherein the mounting bracket is further provided with a first sensor, the first sensor being used to detect whether a bushing is inserted into the stator.

[0015] The bushing press-fit structure of the oil pan includes a positioning pin on the upper surface of the support base, which is used to insert into the corresponding positioning hole of the oil pan; the upper surface of the positioning plate is also provided with multiple anti-fooling blocks.

[0016] The bushing press-fit structure of the oil pan, wherein the upper surface of the positioning plate is provided with a plurality of second sensors, all of which are used to detect whether an oil pan is placed on the positioning plate.

[0017] The oil pan bushing press-fit structure includes a pressing mechanism comprising a pressing cylinder with its output end facing upward, a hinge seat disposed on the cylinder body of the pressing cylinder, and a pressing rod having one end connected to the output end of the pressing cylinder and the other end fixedly connected to a pressing pin; the middle part of the pressing rod is hinged to the hinge seat; and the lower surface of the pressing pin is used to abut against the upper surface of the oil pan.

[0018] Beneficial effects:

[0019] This utility model provides a bushing press-fit structure for an oil pan. A support base is provided for supporting and positioning the oil pan; a clamping mechanism is provided for pressing and fixing the oil pan to a positioning plate; and a press-fit mechanism is provided for press-fitting the bushing into the mounting hole of the oil pan. This structure ensures the precise position of the oil pan during the press-fitting process, provides a precise reference for the bushing press-fitting, guarantees that the bushing can be accurately pressed into the corresponding mounting hole, improves the fitting accuracy between the bushing and the mounting hole, and reduces installation problems caused by positional deviations. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the press-fit structure for the oil pan bushing.

[0021] Figure 2 This is a schematic diagram of the press-fit structure of the oil pan bushing after the oil pan has been placed.

[0022] Figure 3 This is a schematic diagram of the press-fitting mechanism.

[0023] Figure 4 This is a schematic diagram of the oil pan structure.

[0024] Key component symbols: 1-Positioning plate, 11-Support base, 111-Positioning pin, 12-Anti-foolproof block, 13-Second sensor, 2-Pressure clamping mechanism, 21-Pressure clamping cylinder, 22-Hinge base, 23-Pressure rod, 24-Pressure nail, 3-Pressure fitting mechanism, 31-Mounting bracket, 311-First limit plate, 312-Second limit plate, 313-First sensor, 32-Drive cylinder, 33-Fixing plate, 34-Pressure sensor, 35-Pressure head, 36-Stabilizing core, 37-Guide sleeve, 38-Guide rod, 39-Stroke sensor pressure plate; 10-Oil pan, 101-Mounting hole, 102-Positioning hole, 20-Bushing. Detailed Implementation

[0025] This utility model provides a bushing press-fit structure for an oil pan. To make the purpose, technical solution, and effects of this utility model clearer and more explicit, the following describes this utility model in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit the scope of protection of this utility model.

[0026] Please see Figure 1 , Figure 2 and Figure 4 This utility model provides a bushing press-fit structure for an oil pan, including a frame (not shown in the figure), a positioning plate 1 disposed on the frame, a plurality of support seats 11 disposed on the positioning plate 1 and a pressing mechanism 2, and a pressing mechanism 3 disposed on the frame; the support seats 11 are used to support the oil pan 10; the pressing mechanism 2 is used to press the oil pan 10 onto the positioning plate 1; the pressing mechanism 3 is used to press the bushing 20 into the mounting hole 101 of the oil pan 10.

[0027] In practical applications, the oil pan 10 is first supported and positioned using the support base 11 to determine its placement. Then, the pressing mechanism 2 applies a pressing force to the oil pan 10 to press and fix it. This pressing force is evenly distributed on the oil pan 10 to prevent it from moving during the pressing process of the bushing 20. The pressing mechanism 3 is in a standby state on the frame. After the oil pan 10 is correctly positioned and fixed, the bushing 20 is pressed into the mounting hole 101 of the oil pan 10 under the action of the pressing mechanism 3.

[0028] In the above structure, the design of the positioning plate 1 and multiple support seats 11 ensures the precise position of the oil pan 10 during the press-fitting process, providing a precise reference for the press-fitting of the bushing 20. This ensures that the bushing 20 can be accurately pressed into the corresponding mounting hole 101, improving the fitting accuracy between the bushing 20 and the mounting hole 101 and reducing installation problems caused by positional deviations. Moreover, the entire press-fitting structure is rationally designed, with each component working in concert, making the press-fitting operation of the bushing 20 streamlined and efficient. Operators only need to place the oil pan 10 on the support seat 11 and start the clamping mechanism 2 and the press-fitting mechanism 3 to complete the press-fitting, making the operation simple and convenient.

[0029] Please see Figure 3In some embodiments, the pressing mechanism 3 includes a mounting bracket 31 fixedly connected to the frame, a drive cylinder 32 with its cylinder body disposed on the mounting bracket 31 and its output end facing the mounting hole 101 of the oil pan 10, a pressing head 35 connected to the output end of the drive cylinder 32, and a centering core 36 disposed at the end of the pressing head 35; the centering core 36 is used for inserting the bushing 20; the drive cylinder 32 is used to drive the pressing head 35 and the centering core 36 to reciprocate along the axial direction of the mounting hole 101 of the oil pan 10. In actual use, the operator first inserts the bushing 20 to be pressed into the centering core 36, which provides a precise initial positioning for the bushing 20. The subsequent axial movement allows the bushing 20 to enter the mounting hole 101 along a precise axial path during the press-fitting process. This effectively prevents angular deviations or offsets of the bushing 20 during press-fitting, ensuring the coaxiality of the bushing 20 and the mounting hole 101, thereby improving installation accuracy. It also facilitates the normal functioning of the bushing 20 within the oil pan 10, reducing wear and vibration problems caused by installation errors. Furthermore, the mounting bracket 31 is fixedly connected to the frame, providing a stable support structure for the drive cylinder 32, the press head 35, and the centering pin 36. This stable structure ensures that each press-fitting operation is performed under identical conditions, unaffected by external factors such as vibration or shaking. Precise control of the drive cylinder 32 ensures consistent stroke and force of the press head 35 and centering pin 36 each time, guaranteeing that each bushing 20 is pressed into the mounting hole 101 of the oil pan 10 in the same manner and with the same parameters. This achieves a high degree of consistency in installation quality, improving the overall quality and reliability of the product. Preferably, the drive cylinder 32 is a hydraulic cylinder.

[0030] Please see Figure 3In some embodiments, a fixing plate 33 is further provided between the output end of the drive cylinder 32 and the pressure head 35, and a pressure sensor 34 is further provided between the pressure head 35 and the fixing plate 33. The presence of the fixing plate 33 strengthens the connection between the output end of the drive cylinder 32 and the pressure head 35. During the pressing process, especially when the drive cylinder 32 applies a large force, this connection structure can better withstand pressure and impact, preventing the pressure head 35 from loosening or displacing due to force. Moreover, the fixing plate 33 transmits the power of the drive cylinder 32 to the pressure head 35 more stably, further ensuring the accuracy and stability of the bushing 20 pressing process, and helping to maintain the reliable operation of the entire pressing mechanism 3. In addition, the pressure sensor 34 is located between the pressure head 35 and the fixing plate 33, and can monitor the pressure changes during the pressing process in real time. Different pressures are required at different stages during the pressing of the bushing 20 into the mounting hole 101 of the oil pan 10. Through the pressure sensor 34, pressing pressure data can be accurately obtained, and operators or automated control systems can judge the pressing status of the bushing 20 based on this data. For example, when the pressure reaches the preset value, it can be determined that the bushing 20 has been installed in place, avoiding damage to the bushing 20 or the oil pan 10 due to excessive pressure.

[0031] Please see Figure 3 In some embodiments, the mounting bracket 31 is fixedly connected to two or more guide sleeves 37, which are located beside the drive cylinder 32. A guide rod 38 is also slidably disposed within each guide sleeve 37, and the connecting end of the guide rod 38 is fixedly connected to the side wall of the fixing plate 33. In this embodiment, two guide sleeves 37 are preferably located on the front and rear sides of the drive cylinder 32. The two or more guide sleeves 37 fixedly connected to the mounting bracket 31 cooperate with the guide rod 38 slidably disposed therein, providing precise linear motion guidance for the fixing plate 33 and the connected pressure head 35 and centering 36. During the pressing process of the bushing 20, the drive cylinder 32 pushes the pressure head 35 to move, and the guide rod 38 slides within the guide sleeve 37, effectively restricting the other degrees of freedom of the pressure head 35 except for the axial direction. This ensures that the pressure head 35 and the centering pin 36 move strictly along the axial direction of the mounting hole 101 in the oil pan 10, further improving the straightness and positional accuracy of the bushing press-fit, preventing misalignment or other defects in the bushing 20 during the press-fit process, and guaranteeing the installation quality of the bushing 20. Furthermore, the arrangement of multiple guide sleeves 37 and guide rods 38 provides support and guidance to the fixing plate 33 and the press-fit assembly from different directions. This multi-directional guiding structure allows the force generated during the press-fit process to be distributed more evenly, avoiding wobbling or skewness of the pressure head 35 due to unilateral or uneven force.

[0032] Please see Figure 3In some embodiments, a stroke sensor plate 39 is also provided at the free end of the guide rod 38. The stroke sensor plate 39 allows for precise monitoring of the stroke of the pressure head 35 by installing a corresponding stroke sensor. The stroke sensor plate 39, in conjunction with the stroke sensor, can provide real-time feedback of the pressure head 35's position information to the control system. Operators or the automated control system can use this information to accurately determine whether the pressing depth of the bushing 20 meets the requirements, ensuring that each bushing 20 is pressed into the precise position, avoiding insufficient or excessive pressing stroke that could affect the installation quality of the bushing 20 in the oil pan 10. Furthermore, if an abnormal situation occurs during the pressing process, such as blockage of the bushing 20's holes or loss of control of the drive cylinder 32, the stroke sensor plate 39 can trigger a corresponding protection mechanism. Once the stroke of the pressure head 35 exceeds the normal range, the stroke sensor detects the abnormal position of the stroke sensor plate 39, and the system can immediately stop the drive cylinder 32's operation, preventing the pressure head 35 from continuing to move and causing serious damage to the bushing 20, oil pan 10, or the pressing mechanism 3 itself.

[0033] Please see Figure 3 In some embodiments, the mounting bracket 31 is further provided with a first limiting plate 311 and a second limiting plate 312. The first limiting plate 311 and the second limiting plate 312 extend along the length direction of the mounting bracket 31, and both the first limiting plate 311 and the second limiting plate 312 are provided with clearance holes, the size of which is larger than the outer diameter of the pressure head 35. During the pressing process, this can provide lateral restriction for the pressure head 35, preventing lateral displacement of the pressure head 35 and avoiding collisions between the pressure head 35 and other components.

[0034] Please see Figure 3 In some embodiments, the mounting bracket 31 is further provided with a first sensor 313, which is used to detect whether a bushing 20 is inserted into the stator 36. The first sensor 313 can monitor the presence or absence of the bushing 20 on the stator 36 in real time. If the drive cylinder 32 is started before the pressing operation begins, it may result in empty pressing, which not only wastes time and energy but may also damage the pressing mechanism 3 itself. For example, excessive impact force may damage the press head 35 or other related components. The detection by the first sensor 313 can effectively avoid the occurrence of such empty pressing, ensuring that each pressing operation is performed on the premise that the bushing 20 is correctly inserted into the stator 36.

[0035] Please see Figure 1In some embodiments, the upper surface of the support base 11 is provided with a positioning pin 111, which is used to insert into the positioning hole 102 corresponding to the oil pan 10; the upper surface of the positioning plate 1 is also provided with a plurality of anti-misalignment blocks 12. The oil pan 10 has a plurality of positioning holes 102. In this embodiment, the number of support bases 11 is set to five, with positioning pins 111 set on two diagonally opposite support bases 11. This not only satisfies the precise positioning of the oil pan 10, but also shortens the time spent aligning the positioning holes 102 and positioning pins 111 of the oil pan 10, greatly simplifying the assembly process of the oil pan 10 and bushing 20 and accelerating assembly efficiency. The anti-misalignment blocks 12 provide clear directional guidance for the assembly of the oil pan 10 and bushing 20. By restricting the placement direction of the oil pan 10, workers can quickly and accurately place the oil pan 10 in the correct position, avoiding rework caused by incorrect orientation.

[0036] Please see Figure 1 In some embodiments, the upper surface of the positioning plate 1 is further provided with multiple second sensors 13, all of which are used to detect whether an oil pan 10 is placed on the positioning plate 1. When the second sensor 13 detects that there is no oil pan 10 on the positioning plate 1, the pressing structure will not start, thus avoiding meaningless actions by the pressing structure when there is no oil pan 10. Moreover, in an automated production process, the second sensor 13 can quickly report the placement status of the oil pan 10 to the control system. When the oil pan 10 is detected to be in place, the system can immediately start the pressing process without manual confirmation. Conversely, when the oil pan 10 is removed, the system can promptly stop the relevant operations.

[0037] Please see Figure 1 and Figure 2In some embodiments, the clamping mechanism 2 includes a clamping cylinder 21 with its output end facing upward, a hinge seat 22 disposed on the cylinder body of the clamping cylinder 21, and a clamping rod 23 with one end connected to the output end of the clamping cylinder 21 and the other end fixedly connected to a clamping pin 24; the middle part of the clamping rod 23 is hinged to the hinge seat 22; the lower surface of the clamping pin 24 is used to abut against the upper surface of the oil pan 10. In this embodiment, two clamping mechanisms 2 are provided, and the two clamping mechanisms 2 are located diagonally. When it is necessary to clamp the oil pan 10 onto the positioning plate 1, the clamping cylinder 21 is activated, and the output end of the clamping cylinder 21 begins to extend upward. Since the middle part of the clamping rod 23 is hinged to the hinge seat 22, as the output end of the clamping cylinder 21 rises, the clamping rod 23 rotates around the hinge point as a fulcrum. During the rotation of the pressure rod 23, the pressure pin 24 fixed to the end of the pressure rod 23 gradually moves downward, until the lower surface of the pressure pin 24 contacts the upper surface of the oil pan 10. As the output end of the clamping cylinder 21 continues to move upward, the pressure rod 23 rotates further, and the pressure exerted by the pressure pin 24 on the oil pan 10 gradually increases until the oil pan 10 is firmly pressed onto the positioning plate 1. Conversely, after the bushing 20 is pressed in, the output end of the clamping cylinder 21 begins to retract. As the cylinder output end moves downward, the pressure rod 23 rotates in the opposite direction around the hinge point, and the pressure pin 24 gradually leaves the upper surface of the oil pan 10, releasing the clamping force on the oil pan 10, allowing the oil pan 10 to be easily removed from the positioning plate 1. In the above configuration, the lever structure formed by the pressure rod 23 and the hinge seat 22 effectively amplifies the output force of the clamping cylinder 21. Moreover, during the clamping process, as long as the output force of the clamping cylinder 21 is stable, the clamping nail 24 can continuously provide stable pressure to the oil pan 10.

[0038] In summary, this utility model provides a support base 11 for supporting and positioning the oil pan 10; a clamping mechanism 2 for clamping and fixing the oil pan 10 onto the positioning plate 1; and a pressing mechanism 3 for pressing the bushing 20 into the mounting hole 101 of the oil pan 10. This structure ensures the precise position of the oil pan 10 during the pressing process, provides a precise reference for the pressing of the bushing 20, and guarantees that the bushing 20 can be accurately pressed into the corresponding mounting hole 101. This improves the fitting accuracy between the bushing 20 and the mounting hole 101 and reduces installation problems caused by positional deviations.

[0039] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0040] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0041] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0042] It is understood that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of this utility model, and all such substitutions or changes should fall within the protection scope of this utility model.

Claims

1. A grommet press-fit structure of an oil pan, characterized by, The device comprises a rack, a positioning plate arranged on the rack, a plurality of support seats and a pressing mechanism arranged on the positioning plate, and a pressing mechanism arranged on the rack; the support seat is used for supporting an oil pan; the pressing mechanism is used for pressing the oil pan on the positioning plate; and the pressing mechanism is used for pressing a bushing into a mounting hole of the oil pan.

2. The bush press fitting structure of the oil pan according to claim 1, characterized by The pressing mechanism comprises a mounting frame fixed to the rack, a driving cylinder with an output end facing the mounting hole of the oil pan, a pressing head connected to the output end of the driving cylinder, and a core arranged at the end of the pressing head; the core is used for inserting the bushing; and the driving cylinder is used for driving the pressing head and the core to reciprocate along the axial direction of the mounting hole of the oil pan.

3. The bush press fitting structure of the oil pan according to claim 2, characterized by A fixing plate is arranged between the output end of the driving cylinder and the pressing head, and a pressure sensor is arranged between the pressing head and the fixing plate.

4. The bush press fitting structure of the oil pan according to claim 3, characterized by Two or more guide sleeves are fixed to the mounting frame and located beside the driving cylinder; a guide rod is slidably arranged in the guide sleeve, and a connecting end of the guide rod is fixed to a side wall of the fixing plate.

5. The bush press fitting structure of the oil pan according to claim 4, characterized by A stroke sensor pressing plate is arranged at a free end of the guide rod.

6. The bush press fitting structure of the oil pan according to claim 2, characterized by A first limiting plate and a second limiting plate are arranged on the mounting frame and extend along the length direction of the mounting frame; an avoiding hole is arranged on each of the first limiting plate and the second limiting plate, and the size of the avoiding hole is greater than the outer diameter of the pressing head.

7. The bush press fitting structure of the oil pan according to claim 2, characterized by A first sensor is arranged on the mounting frame and used for detecting whether the bushing is inserted into the core.

8. The bush press fitting structure of the oil pan according to claim 1, characterized by, A positioning pin is arranged on the upper surface of the support seat and used for being inserted into a corresponding positioning hole of the oil pan; and a plurality of foolproof blocks are arranged on the upper surface of the positioning plate.

9. The bush press fitting structure of the oil pan according to claim 1, characterized by, A plurality of second sensors are arranged on the upper surface of the positioning plate and used for detecting whether the oil pan is placed on the positioning plate.

10. The bush press fitting structure of the oil pan according to claim 1, characterized by The pressing mechanism comprises a pressing cylinder with an output end facing upward, a hinged seat arranged on the cylinder body of the pressing cylinder, and a pressing rod with one end connected to the output end of the pressing cylinder and the other end fixed with a pressing nail; the middle part of the pressing rod is hinged to the hinged seat; and the lower surface of the pressing nail is used for abutting against the upper surface of the oil pan.

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