High-strength motorcycle crankshaft

Abstract

This utility model discloses a high-strength motorcycle crankshaft, relating to the technical field of core components for motorcycle engines. The high-strength motorcycle crankshaft includes a head main journal with a groove. A flat key is fixedly connected within the groove, and a gear is fixedly attached to the head main journal via the flat key. A front bearing is also fixedly connected to the head main journal. Four crank arms, arranged in two positive and two negative directions along the axis, are fixedly connected to the tail end. The head main journal employs a gradient functional material layered design, with a high-hardness wear-resistant outer layer, a fatigue-resistant transition layer fixedly connected below, and a strong and tough connecting layer fixedly connected to the fatigue-resistant transition layer. It also includes connecting rod journals, a middle main journal, and a tail main journal. The connecting rod journals and the middle main journal have oil injection holes and internal connecting oil passages. This high-strength motorcycle crankshaft solves the problems of insufficient performance matching and poor stability of traditional crankshafts, improving wear resistance, torsional strength, and structural integrity, reducing vibration and wear, and extending service life.

Description

Technical Field

[0001] This utility model relates to the technical field of core components of motorcycle engines, and in particular to a high-strength motorcycle crankshaft. Background Technology

[0002] Traditional crankshafts use homogeneous materials for the journal (the part in contact with the bearing) and crank arm (the part that transmits force), making it difficult to simultaneously meet the differentiated requirements of "high wear resistance of the journal" and "strong toughness of the crank arm". For example, the hardness of the journal surface is increased after quenching and strengthening, but this can easily lead to an increase in overall brittleness, and the crank arm is prone to cracks under rapid acceleration or detonation conditions.

[0003] The crankshaft of a multi-cylinder engine needs to be connected to the journal through multiple crank arms. In the existing design, the crank arms are mostly arranged symmetrically and have not been optimized for the power phase angle of different cylinders. This results in large vibrations when the power of multiple cylinders is superimposed, which affects riding comfort and component life.

[0004] Traditional crankshafts typically have a single axial oil passage design, which can easily lead to lubrication dead zones at the mating surfaces of the journal, connecting rod, and bearings. This is especially true at high speeds (such as above 8000 rpm), where friction and wear are aggravated, requiring frequent maintenance.

[0005] The gears at the front end of the crankshaft (which drive the valve train, etc.) are mostly fixed by interference fit or key connection. Under high-frequency alternating loads, relative slippage is likely to occur, resulting in valve timing deviation, affecting engine efficiency and even causing malfunctions. Utility Model Content

[0006] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a high-strength motorcycle crankshaft that can solve the above-mentioned problems.

[0007] To achieve the above objectives, this utility model provides the following technical solution: a high-strength motorcycle crankshaft, including a head main journal, a groove provided on the head main journal, a flat key fixedly connected in the groove, a gear provided on the head main journal, the gear fixedly connected to the head main journal by the flat key, a front bearing fixedly connected to the head main journal, and a crank arm fixedly connected to the tail end of the head main journal, with a total of four crank arms arranged in two positive and two negative directions along the axis of the head main journal, a high-hardness wear-resistant layer provided on the surface of the head main journal, an anti-fatigue transition layer fixedly connected below the surface layer, a strong and tough connecting layer fixedly connected to the anti-fatigue transition layer, a protective and reinforced anti-torsion strength layer provided on the surface of the crank arm, and a high-toughness buffer layer fixedly connected to the protective and reinforced anti-torsion strength layer;

[0008] A connecting rod journal is provided between two crank arms moving in the same direction. An impact-resistant and wear-resistant layer is provided on the surface of the connecting rod journal. A stress-dispersing layer is fixedly connected to the impact-resistant and wear-resistant layer. A toughness support layer is fixedly connected to the stress-dispersing layer. A central main journal is provided between two crank arms moving in opposite directions.

[0009] The connecting rod journal and the middle main journal are provided with oil injection holes and internal connecting oil passages. A piston arm is fixedly connected to the connecting rod journal, and a base is fixedly connected to the bottom of the piston arm. A connecting hole is provided on the piston arm, and the piston arm and the base are fixedly connected through the connecting hole.

[0010] The tail spindle is fixedly connected to the crank arm furthest from the head spindle.

[0011] Preferably, the connecting oil passage is interconnected inside the connecting rod journal and the middle main journal, and is connected to the oil injection hole.

[0012] Preferably, the high-hardness wear-resistant layer is located on the outermost layer of the head main journal, the fatigue-resistant transition layer is located on the side of the high-hardness wear-resistant layer away from the surface of the head main journal, and the tough connecting layer is located on the side of the fatigue-resistant transition layer away from the high-hardness wear-resistant layer.

[0013] Preferably, the protective and torsional strength-enhancing layer covers the outer surface of the crank arm, and the high-toughness buffer layer is located on the side of the protective and torsional strength-enhancing layer near the center of the crank arm.

[0014] Preferably, the impact-resistant and wear-resistant layer is located on the surface of the connecting rod journal, the stress-dispersing layer is connected to the inner side of the impact-resistant and wear-resistant layer, and the toughness support layer is connected to the side of the stress-dispersing layer away from the impact-resistant and wear-resistant layer.

[0015] Preferably, a tail end bearing is fixedly connected to the tail main journal.

[0016] Preferably, the central main journal is fixed to the middle of the crank arm.

[0017] Preferably, the connecting rod journal is fixed at the small end position of the crank arm.

[0018] Compared with the prior art, the beneficial effects of this utility model are:

[0019] (1) The high-strength motorcycle crankshaft has an impact-resistant and wear-resistant layer on the surface of the connecting rod journal that directly bears the high-frequency impact load transmitted by the piston (especially the impact during knocking), reducing wear and surface peeling. The stress dispersion layer diffuses the impact stress inward to avoid excessive local stress. The toughness support layer serves as the core skeleton to ensure the structural integrity of the connecting rod journal under repeated impacts.

[0020] (2) The high-strength motorcycle crankshaft has a protective and torsional strength layer on the surface of the crank arm to improve torsional performance (resisting torsional loads during rotation). At the same time, it prevents oil impurities from corroding through its oil-resistant properties. The high-toughness buffer layer absorbs impact energy through plastic deformation during engine knocking or rapid acceleration, preventing the crank arm from breaking due to excessive instantaneous stress.

[0021] (3) The high-strength motorcycle crankshaft has a high-hardness wear-resistant layer on the surface of the main journal of the head that directly contacts the front bearing to resist the wear caused by the rolling / sliding friction of the bearing. The fatigue-resistant transition layer buffers the alternating radial stress transmitted by the bearing and avoids stress concentration between the surface and the core due to performance differences. The tough connection layer (located at the small end of the crank arm) ensures a rigid connection with the crank arm and prevents the connection from breaking. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0023] Figure 1 This is a schematic diagram of a high-strength motorcycle crankshaft according to the present invention;

[0024] Figure 2 This is a schematic cross-sectional view of a high-strength motorcycle crankshaft according to the present invention.

[0025] Figure 3 This is a schematic cross-sectional view of a high-strength motorcycle crankshaft main journal according to the present invention.

[0026] Figure 4 This is a schematic cross-sectional view of a high-strength motorcycle crankshaft connecting rod journal according to the present invention.

[0027] Figure 5 This is a partial cross-sectional schematic diagram of a high-strength motorcycle crankshaft crank arm according to the present invention.

[0028] Reference numerals: 1. Head main journal; 2. Gear; 3. Front bearing; 4. Crank arm; 5. Connecting hole; 6. Connecting rod journal; 7. Base; 8. Piston arm; 9. Tail bearing; 10. Oil injection hole; 11. Connecting oil passage; 12. Flat key; 13. Middle main journal; 14. High-hardness wear-resistant layer; 15. Fatigue-resistant transition layer; 16. Strong and tough connecting layer; 17. Protective and reinforced torsional strength layer; 18. High-toughness buffer layer; 19. Impact-resistant and wear-resistant layer; 20. Stress dispersion layer; 21. Toughness support layer; 22. Tail main journal. Detailed Implementation

[0029] This section will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present utility model, but they should not be construed as limiting the scope of protection of the present utility model.

[0030] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0031] In the description of this utility model, terms such as greater than, less than, and exceeding are understood to exclude the stated number, while terms such as above, below, and within are understood to include the stated number. The use of terms like "first" and "second" is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the quantity or sequence of the indicated technical features.

[0032] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0033] Please see Figure 1-5 This utility model provides a technical solution: a high-strength motorcycle crankshaft, including a head main journal 1. The head main journal 1 is provided with a groove, and a flat key 12 is fixedly connected in the groove. A gear 2 is provided on the head main journal 1 and is fixedly connected to the head main journal 1 via the flat key 12. The gear 2, which is fixed on the head main journal 1 via the flat key 12, rotates synchronously with the crankshaft. The gear 2 transmits the rotational power of the crankshaft to other key systems of the engine (such as the camshaft of the valve train, oil pump, ignition system, etc.), realizing the coordinated work of various engine components (such as valve switches, oil circulation, ignition timing, etc.).

[0034] A front bearing 3 is fixedly connected to the head main journal 1, and a crank arm 4 is fixedly connected to the tail of the head main journal 1. There are four crank arms 4 in total, two in the positive direction and two in the negative direction, arranged along the axis of the head main journal 1. A high-hardness wear-resistant layer 14 is provided on the surface of the head main journal 1. An anti-fatigue transition layer 15 is fixedly connected under the surface. A strong and tough connecting layer 16 is fixedly connected to the anti-fatigue transition layer 15. A protective and reinforced anti-torsion strength layer 17 is provided on the surface of the crank arm 4. A high-toughness buffer layer 18 is fixedly connected to the protective and reinforced anti-torsion strength layer 17.

[0035] The high-hardness wear-resistant layer 14 on the surface of the head main journal 1 is in direct contact with the front bearing 3 to resist the wear caused by the rolling / sliding friction of the bearing. The fatigue-resistant transition layer 15 buffers the alternating radial stress transmitted by the bearing and avoids stress concentration between the surface and the core due to performance differences. The strong and tough connecting layer 16 (located at the small end of the crank arm 4) ensures a rigid connection with the crank arm 4 and prevents breakage at the connection.

[0036] The surface protective and torsional strength layer 17 of the crank arm 4 improves torsional performance (resisting torsional loads during rotation) and prevents oil impurities from corroding through its oil-resistant properties. The high-toughness buffer layer 18 absorbs impact energy through plastic deformation during engine knocking or rapid acceleration, preventing the crank arm 4 from breaking due to excessive instantaneous stress.

[0037] A connecting rod journal 6 is provided between two crank arms 4 in the same direction. The surface of the connecting rod journal 6 is provided with an impact-resistant and wear-resistant layer 19. The impact-resistant and wear-resistant layer 19 is fixedly connected to a stress-dispersing layer 20. The stress-dispersing layer 20 is fixedly connected to a toughness support layer 21. The impact-resistant and wear-resistant layer 19 on the surface of the connecting rod journal 6 directly bears the high-frequency impact load transmitted by the piston (especially the impact during knocking), reducing wear and surface peeling. The stress-dispersing layer 20 diffuses the impact stress inward to avoid excessive local stress. The toughness support layer 21 serves as the core skeleton to ensure the structural integrity of the connecting rod journal 6 under repeated impacts.

[0038] A central main journal 13 is provided between two opposing crank arms 4, a connecting rod journal 6 is fixed at the small end of the crank arm 4, and the central main journal 13 is fixed at the middle of the crank arm 4.

[0039] Oil injection holes 10 are provided on the connecting rod journal 6 and the middle main journal 13, and an oil passage 11 is provided inside. A piston arm 8 is fixedly connected to the connecting rod journal 6, and a base 7 is fixedly connected to the bottom of the piston arm 8. A connecting hole 5 is provided on the piston arm 8, and the piston arm 8 and the base 7 are fixedly connected through the connecting hole 5.

[0040] A tail main journal 22 is fixedly connected to the crank arm 4 furthest from the head main journal 1, and a tail end bearing 9 is fixedly connected to the tail main journal 22.

[0041] Working principle: When the motorcycle engine is working, the combustion gases in the cylinder push the piston to make linear reciprocating motion (up and down motion) during the combustion stroke. The piston's power is transmitted to the connecting rod journal 6 through the piston arm 8. Since the connecting rod journal 6 is rigidly connected to the main journals (head main journal 1, middle main journal 13, and tail main journal 22) through the crank arm 4, when the piston drives the connecting rod journal 6 to make up and down motion, the crank arm 4 will make circular rotation around the central axis of the crankshaft (the axis of the head main journal 1), thereby driving the entire crankshaft to rotate synchronously—achieving the key transformation from "piston linear reciprocating motion" to "crankshaft rotational motion", and finally outputting rotational power through the crankshaft (driving the motorcycle wheels to rotate).

[0042] The piston's power is transmitted sequentially through "piston → piston arm 8 → connecting rod journal 6 → crank arm 4 → main journal (head / middle / tail)". The four crank arms 4 are arranged along the axis in a "two positive and two negative" pattern (corresponding to the power phase angle of a multi-cylinder engine, such as the alternating power sequence of a two-cylinder or four-cylinder engine). This ensures that the power of each cylinder's piston is transmitted to the crankshaft in a specific timing sequence, avoiding the impact caused by the superposition of power from multiple cylinders and ensuring smooth crankshaft rotation (reducing vibration).

[0043] The gear 2, which is fixed on the main journal 1 of the head by a flat key 12, rotates synchronously with the crankshaft. The gear 2 transmits the rotational power of the crankshaft to other key systems of the engine (such as the camshaft of the valve train, oil pump, ignition system, etc.), so as to realize the coordinated work of various engine components (such as valve switch, oil circulation, ignition timing, etc.).

[0044] The head main journal 1 is mounted in the bearing housing of the engine block through the front bearing 3 and the tail main journal 22 through the tail bearing 9. The middle main journal 13 further enhances the support stability of the crankshaft. The three together constitute the crankshaft's "rotational support shaft system", which limits the radial runout of the crankshaft, ensures coaxiality during rotation, and avoids additional vibration or wear caused by eccentric rotation.

[0045] The gear 2 is fixed in the groove of the head main journal 1 by a flat key 12. The flat key 12 completely restricts the relative sliding between the gear 2 and the head main journal 1 through the cooperation of the two sides with the groove and the inner hole of the gear 2, ensuring that there is no slippage loss in power transmission and ensuring that the external system driven by the gear 2 (such as the valve train) rotates synchronously with the crankshaft.

[0046] The oil injection holes 10 on the connecting rod journal 6 and the middle main journal 13, together with the internal connecting oil passage 11, form a lubrication channel. When the engine is running, the oil pump pressurizes the oil and delivers it to the oil injection holes 10 through the connecting oil passage 11. This provides forced lubrication to the connection between the connecting rod journal 6 and the piston arm 8, as well as the mating surfaces between the main journal and the bearings (front bearing 3 and rear bearing 9), reducing metal friction and wear. At the same time, the oil carries away the heat generated by the crankshaft rotation (such as frictional heat and heat transferred by the combustion gases) during its flow, preventing local overheating that could lead to a decline in material properties.

[0047] The high-hardness wear-resistant layer 14 on the surface of the head main journal 1 is in direct contact with the front bearing 3 to resist the wear caused by the rolling / sliding friction of the bearing. The fatigue-resistant transition layer 15 buffers the alternating radial stress transmitted by the bearing and avoids stress concentration between the surface and the core due to performance differences. The strong and tough connecting layer 16 (located at the small end of the crank arm 4) ensures a rigid connection with the crank arm 4 and prevents breakage at the connection.

[0048] The surface protective and torsional strength layer 17 of the crank arm 4 improves torsional performance (resisting torsional loads during rotation) and prevents oil impurities from corroding through its oil-resistant properties. The high-toughness buffer layer 18 absorbs impact energy through plastic deformation during engine knocking or rapid acceleration, preventing the crank arm 4 from breaking due to excessive instantaneous stress.

[0049] The impact-resistant and wear-resistant layer 19 on the surface of the connecting rod journal 6 directly bears the high-frequency impact load transmitted by the piston (especially the impact during knocking), reducing wear and surface peeling. The stress dispersion layer 20 diffuses the impact stress inward to avoid excessive local stress. The toughness support layer 21 serves as the core skeleton to ensure the structural integrity of the connecting rod journal 6 under repeated impacts.

[0050] Structural Description:

[0051] Head main journal 1: The front end of the crankshaft, providing a reference axis for the overall rotation. The surface is provided with a high-hardness wear-resistant layer 14, followed by a fatigue-resistant transition layer 15 and a tough connecting layer 16 (layered design of gradient functional materials). The shaft body is machined with grooves for installing a flat key 12, serving as the front-end support core for crankshaft rotation. The high-hardness wear-resistant layer 14 is in direct contact with the front bearing 3 to resist bearing friction and wear. The fatigue-resistant transition layer 15 buffers alternating radial stress and avoids stress concentration between the surface and the core due to performance differences. The tough connecting layer 16 is located at the small end position where it connects to the crank arm 4, ensuring a rigid connection and preventing breakage.

[0052] Gear 2: Sleeve onto the front end of the head main journal 1, fixed by a flat key 12, rotates synchronously with the crankshaft, and transmits rotational power to the valve train, oil pump, ignition system, etc., to realize the coordinated work of various engine components (such as valve switch, oil circulation, ignition timing control).

[0053] Front bearing 3: It is fixedly connected to the side of the head main journal 1 near the gear 2, and cooperates with the head main journal 1 to form the front rotation support point of the crankshaft, which limits radial runout, ensures rotational coaxiality, and reduces eccentric vibration;

[0054] Crank arms 4: There are 4 in total, two in the positive direction and two in the negative direction, arranged along the axis of the head main journal 1. The head main journal 1, the tail, the middle main journal 13, and the tail main journal 22 are all connected by crank arms 4. The surface is provided with a protective and reinforced anti-torsion strength layer 17, under which is a high-toughness buffer layer 18 (layered design of gradient functional materials). It connects the main journal and the connecting rod journal 6 and is the core "bridge" for power transmission. The protective and reinforced anti-torsion strength layer 17 improves the anti-torsion performance, resists rotational torsional loads, and is also resistant to oil corrosion. The high-toughness buffer layer 18 absorbs the impact energy through plastic deformation when the engine knocks or accelerates rapidly, avoiding breakage caused by excessive instantaneous stress. The two positive and two negative arrangement corresponds to the power phase angle of a multi-cylinder engine, so that the power of each cylinder is transmitted in sequence, reducing impact and ensuring smooth rotation.

[0055] Connection hole 5: Located on piston arm 8, the piston arm 8 is fixedly connected to the base 7 by bolts and other fasteners to ensure that the power transmission is secure.

[0056] Connecting rod journal 6: Located between two crank arms 4 in the same direction, fixed at the small end of the crank arm 4, with an impact-resistant and wear-resistant layer 19 on the surface, followed by a stress-dispersing layer 20 and a toughness support layer 21 (layered design of graded functional materials). The shaft body is machined with an oil injection hole 10, which is connected to an oil passage 11 inside. It receives the reciprocating power transmitted by the piston arm 8 and converts it into rotational torque. The impact-resistant and wear-resistant layer 19 directly bears the high-frequency impact load of the piston (especially during knocking), reducing wear and surface peeling. The stress-dispersing layer 20 diffuses the impact stress inward to avoid excessive local stress. The toughness support layer 21 serves as the core skeleton to ensure the structural integrity under repeated impacts.

[0057] Base 7: Fixedly connected to the bottom of piston arm 8, and fastened to piston arm 8 through connecting hole 5, enhancing the connection strength between piston arm 8 and piston, and ensuring the stability of power transmission;

[0058] Piston arm 8: One end is fixedly connected to the connecting rod journal 6, and the other end is connected to the base 7 through the connecting hole 5. It transmits the linear reciprocating motion power of the piston to the connecting rod journal 6 and is the intermediate carrier for the transformation of "reciprocating motion → rotary motion".

[0059] Tail end bearing 9: It is fixedly connected to the tail main journal 22 and cooperates with the tail main journal 22 to form the rear end rotation support point of the crankshaft, which helps to limit radial runout and improves stability during high-speed rotation.

[0060] Oil injection hole 10: It is opened on the surface of the connecting rod journal 6 and the middle main journal 13. It serves as an oil outlet and guides the oil delivered by the oil passage 11 to the connection part between the connecting rod journal 6 and the piston arm 8, and the mating surface between the main journal and the bearings (front bearing 3 and rear bearing 9) to achieve forced lubrication.

[0061] Oil passage 11: runs through the interior of connecting rod journal 6 and central main journal 13, connects oil injection hole 10 with engine oil system, forms a closed lubrication channel, delivers oil pressurized by oil pump to oil injection hole 10, and at the same time carries away frictional heat and combustion heat, avoiding local overheating that leads to a decline in material performance;

[0062] Flat key 12: It is embedded in the groove of the head main journal 1, and its two sides are respectively engaged with the groove and the inner hole of the gear 2, which completely restricts the relative sliding between the gear 2 and the head main journal 1, ensuring that there is no slippage loss in power transmission and ensuring that the gear-driven external system rotates synchronously with the crankshaft.

[0063] The middle main journal 13 is fixed to the middle of the reverse crank arm 4, connects the two reverse crank arms, enhances the support stability of the middle section of the crankshaft, and together with the head main journal 1 and the tail main journal 22, forms a "rotational support shaft system" to further limit radial runout and reduce eccentric vibration.

[0064] High-hardness wear-resistant layer 14 (surface layer of head main journal 1): provides high hardness (≥60HRC) to directly resist rolling / sliding friction wear of front bearing 3;

[0065] Fatigue-resistant transition layer 15 (first surface layer of head main journal): buffers the alternating radial stress transmitted by the bearing, eliminates the abrupt change in performance between the surface layer and the core, and reduces the risk of stress concentration;

[0066] Strong and tough connecting layer 16 (core of head main journal 1): ensures the rigid connection between head main journal 1 and crank arm 4, and improves the fracture resistance of the connection part;

[0067] Protective and reinforced torsional strength layer 17 (crank arm 4 surface): improves the torsional performance of crank arm 4, while resisting oil corrosion and preventing impurities from eroding;

[0068] High-toughness buffer layer 18 (inner layer of crank arm 4): absorbs the impact energy during knocking or rapid acceleration through plastic deformation to prevent crank arm 4 from breaking.

[0069] Impact-resistant and wear-resistant layer 19 (connecting rod journal 6 surface): resists high-frequency impact loads transmitted by the piston, reducing surface peeling and wear;

[0070] Stress dispersion layer 20 (connecting rod journal 6th subsurface layer): diffuses impact stress inward to avoid fatigue cracks caused by local stress concentration;

[0071] Tough support layer 21 (core of connecting rod journal 6): As the core skeleton, it ensures the structural integrity of connecting rod journal 6 under repeated impacts;

[0072] Tail main journal 22: the very end of the crankshaft, fixedly connected to the crank arm 4 furthest from the head main journal 1, serving as the rear end support point of the crankshaft, and cooperating with the tail end bearing 9 to enhance overall rotational stability.

[0073] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. A high-strength motorcycle crankshaft, comprising a head journal (1), characterized in that: The head main journal (1) is provided with a groove, and a flat key (12) is fixedly connected in the groove. A gear (2) is provided on the head main journal (1), and the gear (2) is fixedly connected to the head main journal (1) through the flat key (12). A front bearing (3) is fixedly connected to the head main journal (1). The head main journal (1) is fixedly connected to the tail end of the crank arm (4). There are four crank arms (4) arranged in two positive and two negative directions along the axis of the head main journal (1). The surface of the head main journal (1) is provided with a high hardness wear-resistant layer (14). The surface is fixedly connected with an anti-fatigue transition layer (15). The anti-fatigue transition layer (15) is fixedly connected with a strong and tough connecting layer (16). The surface of the crank arm (4) is provided with a protective and reinforced anti-torsion strength layer (17). The protective and reinforced anti-torsion strength layer (17) is fixedly connected with a high toughness buffer layer (18). A connecting rod journal (6) is provided between two crank arms (4) in the same direction. An impact-resistant and wear-resistant layer (19) is provided on the surface of the connecting rod journal (6). A stress-dispersing layer (20) is fixedly connected to the impact-resistant and wear-resistant layer (19). A toughness support layer (21) is fixedly connected to the stress-dispersing layer (20). A central main journal (13) is provided between two crank arms (4) in opposite directions. Oil injection holes (10) are provided on the connecting rod journal (6) and the middle main journal (13), and an internal connecting oil passage (11) is provided. A piston arm (8) is fixedly connected to the connecting rod journal (6), and a base (7) is fixedly connected to the bottom of the piston arm (8). A connecting hole (5) is provided on the piston arm (8), and the piston arm (8) and the base (7) are fixedly connected through the connecting hole (5). The tail main shaft (22) is fixedly connected to the crank arm (4) furthest from the head main shaft (1).

2. The high-strength motorcycle crankshaft according to claim 1, characterized in that: The connecting oil passage (11) is interconnected with the connecting rod journal (6) and the central main journal (13), and is connected to the oil injection hole (10).

3. A high-strength motorcycle crankshaft according to claim 2, characterized in that: The high-hardness wear-resistant layer (14) is located on the outermost layer of the head main journal (1), the fatigue-resistant transition layer (15) is located on the side of the high-hardness wear-resistant layer (14) away from the surface of the head main journal (1), and the tough connection layer (16) is located on the side of the fatigue-resistant transition layer (15) away from the high-hardness wear-resistant layer (14).

4. A high-strength motorcycle crankshaft according to claim 3, characterized in that: The protective and torsional strength layer (17) covers the outer surface of the crank arm (4), and the high-toughness buffer layer (18) is located on the side of the protective and torsional strength layer (17) near the center of the crank arm (4).

5. A high-strength motorcycle crankshaft according to claim 4, characterized in that: The impact-resistant and wear-resistant layer (19) is located on the surface of the connecting rod journal (6), the stress dispersion layer (20) is connected to the inner side of the impact-resistant and wear-resistant layer (19), and the toughness support layer (21) is connected to the side of the stress dispersion layer (20) away from the impact-resistant and wear-resistant layer (19).

6. A high-strength motorcycle crankshaft according to claim 5, characterized in that: A tail end bearing (9) is fixedly connected to the tail main journal (22).

7. A high-strength motorcycle crankshaft according to claim 6, characterized in that: The central main journal (13) is fixed to the middle of the crank arm (4).

8. A high-strength motorcycle crankshaft according to claim 7, characterized in that: The connecting rod journal (6) is fixed at the small end of the crank arm (4).

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