Large-displacement integral connecting rod

Abstract

The utility model discloses a large-displacement integral type connecting rod which comprises a long-strip-shaped rod body, a large end is arranged at one end of the rod body, a small end is arranged at the other end of the rod body, a round bearing hole is formed in the large end, a round piston hole is formed in the small end, and the center of the piston hole and the center of the bearing hole coincide with the center line of the rod body. And the cross section of the rod body is I-shaped. The large-displacement integral connecting rod is provided with a bearing hole with the specification of phi 45 and the roundness and cylindricity which are not higher than 0.003, a connecting rod body is designed to be an I-shaped reinforced rod body, the load requirement of a large-displacement engine of 300 cc or above is met, and the large-displacement integral connecting rod is manufactured by adopting SCM420H steel in combination with a heat treatment process of secondary tempering. The method meets the requirements of hardness and carburized layer depth of the connecting rod, improves the wear resistance of the connecting rod, and solves the problem of failure caused by deformation of a large hole of the connecting rod.

Description

Technical Field

[0001] The utility model relates to a connecting rod, more specifically, to a large-displacement integral connecting rod. Background Art

[0002] The connecting rod is an important component used in the engine crankshaft. The connecting rod connects the piston cylinder with the crankshaft, converting the reciprocating linear motion of the piston cylinder into the rotary motion of the crankshaft to output power. When used in a larger displacement series engine, the impact load on the connecting rod big end bearing hole will increase, the connecting rod big end bearing hole will become larger, and the hole wall will become thinner. The existing large displacement connecting rod is difficult to guarantee the dimensional accuracy after the bearing hole diameter increases. At the same time, in the operating environment of a large displacement engine, the temperature generated by the rotation will increase. The deformation of the connecting rod processed by the existing process after carburizing and quenching increases when the bearing hole diameter increases, resulting in poor roundness and cylindricity of the connecting rod bearing hole, which affects the wear resistance, thereby affecting the running performance of the needle bearing, and even causing the phenomenon of rotation failure, which needs to be improved. Utility Model Content

[0003] Based on this, it is necessary to provide a large-displacement integral connecting rod to address the above-mentioned technical problems.

[0004] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0005] A large-displacement integral connecting rod, characterized in that the large-displacement integral connecting rod comprises a long strip-shaped rod body, a large end is provided at one end of the rod body, a small end is provided at the other end of the rod body, a circular bearing hole is provided on the large end, a circular piston hole is provided on the small end, the center of the piston hole and the center of the bearing hole coincide with the center line of the rod body, and the cross-section of the rod body is in the shape of an "I".

[0006] As a preferred embodiment of the utility model, the diameter of the bearing hole is greater than 45 mm, the roundness of the bearing hole exceeds 0.003, and the cylindricity of the bearing hole does not exceed 0.003.

[0007] As a preferred embodiment of the present utility model, the distance between the bearing hole and the piston hole is greater than 108 mm.

[0008] As a preferred embodiment of the utility model, the carburized layer depth of the bearing hole is 1.2 to 1.9 mm.

[0009] As a preferred embodiment of the utility model, the large-displacement integral connecting rod is made of SCM420H material.

[0010] Compared with the prior art, the utility model has the following beneficial effects:

[0011] The utility model provides a large-displacement integral connecting rod. The large-displacement integral connecting rod is provided with a bearing hole of φ45, and a roundness and cylindricity not higher than 0.003. The connecting rod body is designed as an "I"-shaped reinforced rod body, which meets the load requirements of large-displacement engines above 300cc. By adopting a heat treatment process method of SCM420H steel combined with a secondary tempering, a process method for reducing the residual stress of the material and thus reducing the deformation of the roundness and cylindricity of the connecting rod bearing hole is adopted, the requirements of the connecting rod hardness and the depth of the carburized layer are met, the wear resistance of the connecting rod is improved, the failure problem caused by the deformation of the large hole of the connecting rod is solved, and the product quality is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the scheme in the utility model, a brief introduction is given below to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 It is a structural schematic diagram of a large displacement integral connecting rod of the utility model;

[0014] Figure 2 for Figure 1 A cross-sectional view of a large displacement integral connecting rod along line AA;

[0015] The markings in the figure are as follows: 1, big end; 2, rod body; 3, small end; 4, bearing hole; 5, piston hole; X, center line. DETAILED DESCRIPTION

[0016] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0017] like Figure 1 and Figure 2 As shown, the large-displacement integral connecting rod comprises a long rod body 2, one end of the rod body 2 is provided with a large end 1, the other end of the rod body 2 is provided with a small end 3, the large end 1 is provided with a circular bearing hole 4, the small end 3 is provided with a circular piston hole 5, the center of the piston hole 5 and the center of the bearing hole 4 coincide with the center line X of the rod body 2, and the cross-section of the rod body 2 is in the shape of an "I".

[0018] It should be noted that the diameter of the bearing hole 4 is greater than 45 mm, the roundness of the bearing hole 4 exceeds 0.003, and the cylindricity of the bearing hole 4 does not exceed 0.003.

[0019] In addition, the distance between the bearing hole 4 and the piston hole 5 is greater than 108 mm.

[0020] The large displacement integral connecting rod is made of SCM420H material.

[0021] The following introduces the processing process of this large-displacement integral connecting rod.

[0022] The processing technology of the large-displacement integral connecting rod includes rough machining, heat treatment and fine machining, wherein the rough machining sequence is blank forging → double end surface grinding → boring. The large-displacement integral connecting rod is forged with SCM420H material, and the forging process includes shot peening on the blank surface.

[0023] The heat treatment process of the large-displacement integral connecting rod adopts carburizing and quenching, which includes overall carburizing air cooling → overall quenching → cleaning → overall tempering → annealing of the rod body 2 and the small end 3, wherein the overall tempering includes primary tempering and secondary tempering. The primary tempering is to keep the connecting rod at a constant temperature of 180°~190° for 2.5 hours, and the secondary tempering is to cool the connecting rod after the primary tempering to room temperature and immediately continue to keep the temperature at 180°~190° for 2.5 hours. After the secondary tempering, the surface hardness of the large end 1 of the connecting rod is HRC60~64, the core hardness is HRC30~48, and the carburizing layer depth of the bearing hole 4 is 1.2~1.9. At the same time, in a high temperature environment of 180° for 12 hours, the deformation of the bearing hole 4 can be guaranteed to be less than 0.002.

[0024] The finishing process sequence of this large-displacement integral connecting rod is end face finishing grinding → hole grinding → honing.

[0025] The large-displacement integral connecting rod is equipped with a φ45 bearing hole, and a roundness and cylindricity not higher than 0.003. The connecting rod body is designed as an "I"-shaped reinforced rod body, which meets the load requirements of large-displacement engines above 300cc. By adopting SCM420H steel combined with a secondary tempering heat treatment process method, the residual stress of the material is reduced, thereby reducing the roundness and cylindricity deformation of the connecting rod bearing hole. The process method meets the requirements of the connecting rod hardness and the depth of the carburized layer, improves the wear resistance of the connecting rod, solves the failure problem caused by the deformation of the large hole of the connecting rod, and improves the product quality.

[0026] Without limitation to this, any changes or substitutions that are not conceived through creative work should be included in the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be based on the protection scope defined in the claims.

Claims

1. A large displacement integral connecting rod, characterized in that: The large displacement integral connecting rod comprises a long strip-shaped rod body (2), one end of the rod body (2) is provided with a large end (1), the other end of the rod body (2) is provided with a small end (3), the large end (1) is provided with a circular bearing hole (4), the small end (3) is provided with a circular piston hole (5), the center of the piston hole (5), the center of the bearing hole (4) and the center line (X) of the rod body (2) coincide, the cross section of the rod body (2) is in the shape of an "I", the diameter of the bearing hole (4) is greater than 45 mm, the roundness of the bearing hole (4) exceeds 0.003, the cylindricality of the bearing hole (4) does not exceed 0.003, the distance between the bearing hole (4) and the piston hole (5) is greater than 108 mm, the carburized layer depth of the bearing hole (4) is 1.2-1.9 mm, and the large displacement integral connecting rod is made of SCM420H material.

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