Bolt, engine assembly with same and vehicle

Abstract

The bolt comprises a bolt head and a screw rod, an inner hexagonal groove is formed in the bolt head, the screw rod comprises a connecting section and a threaded section, the connecting section is connected with the bolt head and the threaded section, threads are formed on the threaded section, and the outer diameter of the connecting section is larger than that of the threaded section. According to the bolt, the inner hexagonal groove is formed in the bolt head, so that the bolt head can have a smaller radial size, the weight of the bolt can be well reduced, the outer diameter of the connecting section is larger than the outer diameter of the threaded section, the cross sectional area of the connecting section in the axial direction of the bolt can be increased, and the service life of the bolt is prolonged. Therefore, the shearing strength of the connecting section can be well improved, and the bolt strength is improved, so that the stability and reliability of bolt connection are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of vehicles, in particular to a bolt and an engine assembly and a vehicle having the bolt. Background Art

[0002] Bolts are widely used in technical fields such as machinery, construction, vehicles, aerospace, etc. due to their simple structure, easy installation and disassembly, and strong load capacity. However, with the rapid development and innovation of technologies in the above-mentioned fields, the requirements for the connection stability and structural strength of bolts, such as shear resistance, have also increased. Related technologies usually use larger size bolts to ensure stronger shear strength and provide greater clamping force, but the weight and cost of the bolts also increase. Utility Model Content

[0003] The utility model provides a bolt, which has the advantages of light weight and high shear strength.

[0004] The utility model also provides an engine assembly with the bolt.

[0005] The utility model also provides a vehicle with the engine assembly.

[0006] According to the first aspect of the present invention, the bolt comprises: a bolt head having a hexagonal groove formed thereon; a screw rod comprising a connecting section and a threaded section, the connecting section connecting the bolt head and the threaded section, the threaded section having threads formed thereon, and an outer diameter of the connecting section being greater than an outer diameter of the threaded section.

[0007] According to the bolt of the embodiment of the first aspect of the utility model, a hexagonal groove is formed on the bolt head, so that the bolt head can have a smaller radial dimension, thereby reducing the weight of the bolt. The screw rod includes a connecting section and a threaded section. The connecting section connects the bolt head and the threaded section. A thread is formed on the threaded section. The outer diameter of the connecting section is larger than the outer diameter of the threaded section. The cross-sectional area of ​​the connecting section in the axial direction of the bolt can be increased, thereby improving the shear strength of the connecting section, which is beneficial to improving the strength of the bolt to improve the stability and reliability of the bolt connection.

[0008] According to some embodiments of the present invention, the outer diameter D1 of the connecting section and the outer diameter D2 of the threaded section satisfy: 0.4≤D1-D2≤0.6mm.

[0009] According to some embodiments of the present invention, in the axial direction of the bolt, the length L1 of the connecting section and the length L2 of the threaded section satisfy: 1 / 9≤L1 / L2≤1 / 7.

[0010] According to some embodiments of the present invention, anti-loosening glue is provided on at least a portion of the threaded section.

[0011] According to some embodiments of the utility model, in the axial direction of the bolt, an end of the anti-loosening glue facing away from the bolt head is spaced apart from an end of the threaded section facing away from the bolt head.

[0012] According to some embodiments of the present invention, in the axial direction of the bolt, a distance L3 between one end of the anti-loosening glue away from the bolt head and one end of the thread segment away from the bolt head, and a pitch L4 of the thread segment satisfy: L3 / L4≥2.

[0013] According to some embodiments of the present invention, the length L5 of the anti-loosening glue in the axial direction of the bolt and the outer diameter D2 of the threaded segment satisfy: 1≤L5 / D2≤1.5; and / or the anti-loosening glue extends in a ring shape along the circumference of the threaded segment.

[0014] According to some embodiments of the present invention, the bolt head is cylindrical; and / or the hexagonal groove is flower-shaped.

[0015] According to some embodiments of the utility model, the screw rod also includes a guide section arranged at one end of the threaded section away from the connecting section, and the diameter of the guide section gradually decreases in the direction along the axial direction of the bolt toward the threaded section away from the connecting section, and the maximum diameter of the guide section is the same as the outer diameter of the threaded section.

[0016] The engine assembly according to the second embodiment of the utility model comprises: a crankshaft, a flywheel and the above-mentioned bolts, wherein the crankshaft and the flywheel are connected by the bolts.

[0017] According to the engine assembly of the second aspect of the utility model, the connection strength between the crankshaft and the flywheel can be improved by high-strength bolts to improve the stability of the engine assembly. The light weight of the bolts is conducive to improving the lightweight level of the engine assembly.

[0018] A vehicle according to an embodiment of the third aspect of the utility model includes: the above-mentioned engine assembly.

[0019] According to the vehicle of the third aspect of the utility model, the connection strength between the crankshaft and the flywheel can be improved by high-strength bolts to improve the stability of the engine assembly. The light weight of the bolts is conducive to improving the lightweight level of the engine assembly, thereby improving the stability and lightweight level of the vehicle.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a front view of a bolt according to an embodiment of the utility model;

[0022] Figure 2 It is a side view of the bolt in the axial direction according to an embodiment of the utility model.

[0023] Reference numerals:

[0024] Bolt 100;

[0025] Bolt head 10; hexagonal groove 11; screw rod 20; connecting section 21; threaded section 22; guide section 23; anti-loosening glue 30. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0027] The disclosure below provides many different embodiments or examples for realizing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the utility model. In addition, the utility model can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the utility model provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the applicability of other processes and / or the use of other materials.

[0028] The bolt 100 according to an embodiment of the first aspect of the utility model is described below with reference to the drawings.

[0029] like Figure 1 and Figure 2As shown, the bolt 100 according to the embodiment of the first aspect of the utility model comprises: a bolt head 10 and a screw rod 20, wherein a hexagonal inner groove 11 is formed on the bolt head 10, and the screw rod 20 comprises a connecting section 21 and a threaded section 22, wherein the connecting section 21 connects the bolt head 10 and the threaded section 22, and a thread is formed on the threaded section 22. The hexagonal inner groove 11 is arranged on the axial end face of the bolt head 10 away from the screw rod 20, and by arranging the hexagonal inner groove 11 on the bolt head 10, compared with the external hexagonal bolt in the related art, the bolt head 10 can have a smaller radial dimension, thereby being able to better reduce the weight of the bolt head 10 and thus reduce the weight of the bolt 100. In addition, in the axial direction of the bolt 100, one end of the connecting section 21 is connected to the bolt head 10, and the other end of the connecting section 21 is connected to the threaded section 22, that is, the bolt head 10 and the threaded section 22 are connected as a whole through the connecting section 21. This can ensure that while the bolt 100 is connected to the connecting component through the threaded section 22, there is no need to set threads on the connecting section 21, thereby better ensuring the cross-sectional area of ​​the connecting section 21 in the axial direction of the bolt 100 to improve the shear strength of the connecting section 21, which is beneficial to improving the stability and reliability of the connection of the bolt 100.

[0030] The outer diameter of the connecting section 21 is greater than the outer diameter of the threaded section 22. The outer diameter of the threaded section 22 here refers to the major diameter of the thread on the threaded section 22, that is, in the axial direction of the bolt 100, the cross-sectional area of ​​the connecting section 21 is greater than the cross-sectional area of ​​the threaded section 22. Therefore, the cross-sectional area of ​​the connecting section 21 in the axial direction of the bolt 100 can be increased by increasing the outer diameter of the connecting section 21, so that the shear strength of the connecting section 21 can be improved, which is conducive to improving the strength of the bolt 100 to improve the stability and reliability of the connection of the bolt 100.

[0031] According to the bolt 100 of the embodiment of the first aspect of the utility model, a hexagonal groove 11 is formed on the bolt head 10, so that the bolt head 10 can have a smaller radial dimension, thereby reducing the weight of the bolt 100. The screw rod 20 includes a connecting section 21 and a threaded section 22. The connecting section 21 connects the bolt head 10 and the threaded section 22. A thread is formed on the threaded section 22. The outer diameter of the connecting section 21 is greater than the outer diameter of the threaded section 22. The cross-sectional area of ​​the connecting section 21 in the axial direction of the bolt 100 can be increased, thereby improving the shear strength of the connecting section 21, which is beneficial to improving the strength of the bolt 100 to improve the stability and reliability of the connection of the bolt 100.

[0032] According to some embodiments of the present invention, the outer diameter D1 of the connection section 21 and the outer diameter D2 of the threaded section 22 satisfy: 0.4≤D1-D2≤0.6mm. That is, the difference in the outer diameters of the connection section 21 and the threaded section 22 is controlled within the range of 0.4mm to 0.6mm. For example, the difference in the outer diameters of the connection section 21 and the threaded section 22 can be 0.4mm, or 0.42mm, or 0.45mm, or 0.5mm, or 0.53mm, or 0.57mm, or 0.6mm, etc., and no specific restrictions are made here. Among them, the larger the difference in the outer diameters of the connection section 21 and the threaded section 22, the larger the outer diameter of the connection section 21 or the smaller the inner diameter of the threaded section 22. If the outer diameter of the connection section 21 is too large, the overall weight of the bolt 100 will be increased, and if the inner diameter of the threaded section 22 is too small, the shear strength will be affected; the smaller the difference in the outer diameters of the connection section 21 and the threaded section 22, the smaller the cross-sectional area of ​​the connection section 21 to be increased in the axial direction of the bolt 100. Therefore, by controlling the difference in outer diameters between the connecting section 21 and the threaded section 22 within the range of 0.4 mm to 0.6 mm, the shear strength of the connecting section 21 can be improved while controlling the weight of the connecting section 21 and ensuring the shear strength of the threaded section 22. This can improve the strength of the bolt 100 while controlling the weight of the bolt 100.

[0033] According to some embodiments of the present invention, in the axial direction of the bolt 100, the length L1 of the connection section 21 and the length L2 of the threaded section 22 satisfy: 1 / 9≤L1 / L2≤1 / 7. That is, the length ratio of the connection section 21 to the threaded section 22 in the axial direction of the bolt 100 is controlled within the range of 1 / 9 to 1 / 7. For example, the length ratio of the connection section 21 to the threaded section 22 in the axial direction of the bolt 100 may be 1 / 9, or 17 / 144, or 1 / 8, or 15 / 112, or 1 / 7, etc., and no specific limitation is made here. The greater the length ratio of the connecting section 21 to the threaded section 22 in the axial direction of the bolt 100, the longer the length of the connecting section 21 or the shorter the length of the threaded section 22. If the length of the connecting section 21 is too long, the overall weight and axial size of the bolt 100 will be increased. If the length of the threaded section 22 is too short, the connection area between the bolt 100 and the connection component will be reduced, affecting the connection strength. The smaller the length ratio of the connecting section 21 to the threaded section 22 in the axial direction of the bolt 100, the shorter the length of the connecting section 21 or the longer the length of the threaded section 22. If the length of the connecting section 21 is too short, it is not conducive to the stability of the connection between the bolt head 10 and the threaded section 22. If the length of the threaded section 22 is too long, the overall weight and axial size of the bolt 100 will be increased. Therefore, by controlling the length ratio of the connecting section 21 to the threaded section 22 in the axial direction of the bolt 100 within the range of 1 / 9 to 1 / 7, the overall weight and axial size of the bolt 100 can be controlled while ensuring the stability of the connecting section 21 connecting the bolt head 10 and the threaded section 22.

[0034] According to some embodiments of the utility model, at least part of the threaded section 22 is provided with an anti-loosening glue 30. Therefore, during the assembly process of the bolt 100, as the threaded section 22 is gradually screwed into the installation position, the anti-loosening glue 30 can better fill the gap between the threaded section 22 and the connection position, such as filling in the gap between the thread teeth, so as to better prevent the threaded section 22 from shaking. Thus, the anti-loosening glue 30 on the threaded section 22 can better prevent the bolt 100 from loosening after installation, which is conducive to improving the stability and reliability of the connection of the bolt 100. In addition, the anti-loosening glue 30 can better improve the sealing effect between the threaded section 22 and the connection position to improve the sealing of the bolt 100 after being assembled at the connection position. Among them, the anti-loosening glue 30 can be provided on part of the threaded section 22, such as only setting the anti-loosening glue 30 at the threaded connection position to save the use cost of the anti-loosening glue 30, and the threaded section 22 can also be completely covered with the anti-loosening glue 30, which is not specifically limited here.

[0035] According to some embodiments of the utility model, in the axial direction of the bolt 100, the end of the anti-loosening glue 30 away from the bolt head 10 is spaced apart from the end of the threaded section 22 away from the bolt head 10. That is to say, the outer peripheral wall of the end of the threaded section 22 away from the bolt head 10 in the axial direction of the bolt 100 is not covered by the anti-loosening glue 30. Therefore, in the pre-positioning process of installing the bolt 100, when the operator inserts the bolt 100 into the connecting hole, the part of the end of the threaded section 22 not covered by the anti-loosening glue 30 can be preliminarily matched with the thread in the connecting hole, such as pre-tightening, so as to achieve the pre-positioning of the bolt 100. As a result, the difficulty of pre-positioning during the installation of the bolt 100 can be well reduced, which is conducive to reducing the difficulty of using the bolt 100 and improving the installation efficiency of the bolt 100.

[0036] According to some embodiments of the utility model, in the axial direction of the bolt 100, the distance L3 between the end of the anti-loosening glue 30 away from the bolt head 10 and the end of the threaded section 22 away from the bolt head 10, and the pitch L4 of the threaded section 22 satisfy: L3 / L4≥2. That is, the ratio of the length of the area of ​​the end of the threaded section 22 away from the bolt head 10 in the axial direction of the bolt 100 that is not covered by the anti-loosening glue 30 to the pitch of the threaded section 22 is controlled within a range of not less than 2. For example, the ratio of the length of the area of ​​the end of the threaded section 22 away from the bolt head 10 in the axial direction of the bolt 100 that is not covered by the anti-loosening glue 30 to the pitch of the threaded section 22 can be 2, or 2.1, or 2.3, or 2.5, or 2.8, or 3, etc., and no specific restrictions are made here. That is, it is ensured that at least twice the length of the pitch of the threaded section 22 is reserved at the end of the threaded section 22 away from the bolt head 10 in the axial direction of the bolt 100 to facilitate the pre-tightening and positioning of the threaded section 22. Therefore, the accuracy of pre-positioning of the bolt 100 during installation can be better guaranteed.

[0037] According to some embodiments of the present invention, the length L5 of the anti-loosening glue 30 in the axial direction of the bolt 100 and the outer diameter D2 of the threaded segment 22 satisfy: 1≤L5 / D2≤1.5. That is, the ratio of the length of the anti-loosening glue 30 covering the threaded segment 22 in the axial direction of the bolt 100 to the outer diameter of the threaded segment 22 is controlled between 1 and 1.5. For example, the ratio of the length of the anti-loosening glue 30 covering the threaded segment 22 in the axial direction of the bolt 100 to the outer diameter of the threaded segment 22 can be 1, or 1.1, or 1.2, or 1.32, or 1.46, or 1.5, etc., and no specific limitation is made here. In this way, it is possible to better avoid the filling effect of the anti-loosening glue 30 being affected by the ratio of the axial length of the bolt 100 to the outer diameter of the threaded segment 22 being too small. At the same time, it is possible to prevent the excessive application of the anti-loosening glue 30 and the waste caused by the ratio of the axial length of the bolt 100 to the outer diameter of the threaded segment 22 being too large. This can ensure the anti-loosening effect of the anti-loosening glue 30 while controlling the use cost of the anti-loosening glue 30.

[0038] According to some embodiments of the present invention, the anti-loosening glue 30 extends in a ring shape along the circumference of the threaded segment 22. Therefore, when the threaded segment 22 is screwed into the connection position, the anti-loosening glue 30 can fill the gap between the threaded segment 22 and the connection position in the circumference of the threaded segment 22, which is beneficial to improve the filling effect of the anti-loosening glue 30 to prevent the bolt 100 from loosening.

[0039] In some embodiments, the length L5 of the anti-loosening glue 30 in the axial direction of the bolt 100 and the outer diameter D2 of the threaded section 22 satisfy: 1≤L5 / D2≤1.5, and the anti-loosening glue 30 extends in a ring shape along the circumference of the threaded section 22. Thus, the use cost of the anti-loosening glue 30 can be controlled while ensuring the anti-loosening effect of the anti-loosening glue 30.

[0040] According to some embodiments of the present invention, the bolt head 10 is cylindrical. The cylindrical bolt head 10 has a regular shape, is easy to manufacture and process, and can reduce the presence of edges and corners to avoid the risk of scratches and scratches during the installation of the bolt 100. It can also reduce the volume of the bolt head 10 to reduce the overall weight of the bolt 100.

[0041] According to some embodiments of the present invention, the hexagonal groove 11 is in a flower shape. That is, the bolt 100 is a hexagonal flower-shaped bolt 100, wherein the flower-shaped hexagonal socket has high anti-slip performance and is convenient for installation tools such as hexagonal wrenches to be inserted, thereby reducing the difficulty of matching the installation tools with the hexagonal groove 11, which is conducive to reducing the difficulty of assembling the bolt 100 and improving the assembly efficiency of the bolt 100.

[0042] In some embodiments, the bolt head 10 is cylindrical, and the hexagonal recess 11 is flower-shaped. Thus, the assembly efficiency of the bolt 100 is improved while reducing the production and processing difficulty of the bolt 100, reducing the overall weight of the bolt 100, and reducing the assembly difficulty of the bolt 100.

[0043] According to some embodiments of the present invention, the screw 20 further includes a guide section 23 disposed at one end of the threaded section 22 away from the connection section 21. In the direction of the axial direction of the bolt 100 toward the threaded section 22 away from the threaded section 22, the diameter of the guide section 23 gradually decreases, and the maximum diameter of the guide section 23 is the same as the outer diameter of the threaded section 22. In other words, the diameter of the end of the guide section 23 connected to the threaded section 22 is larger than the diameter of the other end of the guide section 23. In the direction toward the threaded section 22, the outer peripheral wall of the guide section 23 extends obliquely toward the direction away from the central axis of the bolt 100, so that a guide slope can be formed on the outer peripheral wall of the guide section 23. Therefore, when the bolt 100 is inserted into the connection position during installation, the insertion direction of the bolt 100 can be better guided by the guide slope, so as to better correct the position deviation when the bolt 100 is aligned with the connection position, so as to reduce the installation difficulty of the bolt 100. Among them, the bolt head 10, the connection section 21, the threaded section 22 and the guide section 23 are coaxially arranged.

[0044] In a specific example, the bolt 100 is made of high-purity high-quality alloy steel 42CrMoVNb (the specific chemical composition of the above material is: C: 0.40-0.45%, Si: ≤0.20%, Mn: 0.30-0.55%, P: ≤0.01%, S: ≤0.01%, Cr: 1.0-1.2%, Mo: 0.20-0.60%, V: 0.15-0.35%, Nb: 0.02-0.05%, Cu: ≤0.20%, Al: ≥0.015%; Grain size: ≥7; Macrostructure: No visible shrinkage, bubbles, delamination, cracks, inclusions, white spots. General looseness, center looseness, ingot segregation are all ≤2.0. Wire rod square segregation requirement level ≤1.5; Decarburization: No ferrite decarburization is allowed; Hardness: Spheroidizing annealing hardness (HB) ≤180; No cracks in cold forging test; Non-metallic inclusions ≤1 level) Cold heading forming, After isothermal heat treatment (specific process: quenching temperature 890℃, carbon potential 0.40, time 80 minutes, salt bath temperature 320℃), rolling thread, phosphating oiling, and finally pre-coating chemical glue, it can finally meet the metallographic structure of 14.9 grade ultra-high strength bolt 100 (the metallographic structure is lower bainite, of which the thread core has at least 90% bainite structure, and a maximum of 10% island martensite is allowed. Martensite should not appear continuously, and the diameter of the island martensite should not be More than 80μm), performance (tensile strength: 1400-1550MPa; yield strength: ≥1260Mpa; hardness: 425-475HV) and hydrogen embrittlement requirements (tighten using an axial force testing machine to reach the yield point of the bolt 100 and record the torque value, retighten every 24 hours and apply the tightening torque used in the initial test. The test should last at least 48 hours. After 48 hours, there should be no visible cracks or breaks in the bolt 100).

[0045] The engine assembly according to the second embodiment of the utility model is described below with reference to the accompanying drawings.

[0046] According to the engine assembly of the second embodiment of the utility model, it includes: a crankshaft, a flywheel and a bolt 100, and the crankshaft and the flywheel are connected by the bolt 100. Therefore, the connection strength between the crankshaft and the flywheel can be improved by the high-strength bolt 100, so as to improve the stability of the engine assembly. In addition, the bolt 100 is light in weight, which is conducive to improving the lightweight level of the engine assembly. In a specific example, the bolt 100 is screwed onto the crankshaft through the flywheel of the engine assembly through the tightening process of the torque plus angle method. An engine uses eight bolts 100. The huge clamping force and sealing force generated by tightening these eight bolts 100 ensure that the flywheel and crankshaft of the engine assembly are firmly fastened and sealed, thereby ensuring the normal high-speed operation of the entire engine assembly and ensuring that the thermal efficiency of the entire engine assembly is greater than 46%.

[0047] According to the engine assembly of the second aspect of the utility model, the connection strength between the crankshaft and the flywheel can be improved by the high-strength bolt 100, so as to improve the stability of the engine assembly. The bolt 100 is light in weight, which is conducive to improving the lightweight level of the engine assembly.

[0048] A vehicle according to an embodiment of the third aspect of the utility model will be described below with reference to the accompanying drawings.

[0049] A vehicle according to an embodiment of the third aspect of the utility model includes: an engine assembly.

[0050] According to the vehicle of the third aspect of the utility model, the connection strength between the crankshaft and the flywheel can be improved through the high-strength bolt 100, so as to improve the stability of the engine assembly. The light weight of the bolt 100 is conducive to improving the lightweight level of the engine assembly, thereby improving the stability and lightweight level of the vehicle.

[0051] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0053] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A bolt, characterized in that: include: A bolt head, wherein a hexagonal groove is formed on the bolt head; A screw rod, comprising a connecting section and a threaded section, wherein the connecting section connects the bolt head and the threaded section, a thread is formed on the threaded section, an outer diameter of the connecting section is larger than an outer diameter of the threaded section, and anti-loosening glue is provided on at least a portion of the threaded section.

2. The bolt according to claim 1, characterized in that The outer diameter D1 of the connecting section and the outer diameter D2 of the threaded section satisfy: 0.4≤D1-D2≤0.6mm.

3. The bolt according to claim 1, characterized in that: In the axial direction of the bolt, the length L1 of the connecting section and the length L2 of the threaded section satisfy: 1 / 9≤L1 / L2≤1 / 7.

4. The bolt according to claim 1, characterized in that In the axial direction of the bolt, an end of the anti-loosening glue facing away from the bolt head is spaced apart from an end of the threaded section facing away from the bolt head.

5. The bolt according to claim 4, characterized in that In the axial direction of the bolt, a distance L3 between an end of the anti-loosening glue away from the bolt head and an end of the thread segment away from the bolt head, and a pitch L4 of the thread segment satisfy: L3 / L4≥2.

6. The bolt according to claim 1, characterized in that The length L5 of the anti-loosening glue in the axial direction of the bolt and the outer diameter D2 of the threaded section satisfy: 1≤L5 / D2≤1.5; and / or, the anti-loosening glue extends in a ring shape along the circumference of the threaded section.

7. The bolt according to claim 1, characterized in that The bolt head is cylindrical; and / or the hexagonal inner groove is flower-shaped.

8. The bolt according to claim 1, characterized in that The screw rod also includes a guide section arranged at one end of the threaded section away from the connecting section. The diameter of the guide section gradually decreases in the direction of the threaded section away from the axial direction of the bolt, and the maximum diameter of the guide section is the same as the outer diameter of the threaded section.

9. An engine assembly, characterized in that: include: A crankshaft, a flywheel and bolts, wherein the bolts are bolts according to any one of claims 1 to 8, and the crankshaft and the flywheel are connected by the bolts.

10. A vehicle, characterized in that: include: The engine assembly according to claim 9.

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