A lubricating structure of a motorcycle camshaft

Abstract

The application provides a motorcycle camshaft lubricating structure and belongs to the technical field of motorcycles. The motorcycle camshaft lubricating structure solves the problem of insufficient working stability of the existing motorcycle camshaft decompression structure. The motorcycle camshaft lubricating structure comprises a oil dripping protrusion arranged on a cylinder head, the side of an exhaust cam facing a flyweight is a mounting surface, and a boss portion is integrally formed on the mounting surface; the oil dripping protrusion faces the boss portion and the boss portion is below the oil dripping protrusion; an extension portion is integrally formed on one side of the boss portion; a mounting through hole is formed in the extension portion; an oil passing gap is formed between the extension portion and the mounting surface; one end of the flyweight is connected with a pin shaft inserted into the mounting through hole; an installation gap is formed on the other side of the boss portion on the camshaft; and a decompression pin is arranged in the installation gap. The motorcycle camshaft lubricating structure can ensure that the camshaft decompression structure of the motorcycle has high working stability, has the advantages of low improvement cost, and is suitable for wide use and popularization.

Description

Technical Field

[0001] This invention belongs to the field of motorcycle technology and relates to a lubrication structure for a motorcycle camshaft. Background Technology

[0002] When a motorcycle engine starts, it needs to draw in new gas for compression. Near the end of the compression, a large compression resistance will be generated. If the pressure is not reduced at this time, the starting force will increase and starting will be very difficult. Therefore, a camshaft pressure reduction structure is needed to reduce the pressure and ensure that the engine starts smoothly.

[0003] Existing motorcycle camshaft decompression structures, such as the engine camshaft decompression valve disclosed in Chinese patent document (application number: CN201921559477.8), include a camshaft body, on which an intake cam and an exhaust cam are mounted. A decompression pin and a torsion spring mounting seat with a torsion spring are mounted on the outer end face of the exhaust cam. A decompression valve slinger is mounted on the camshaft body outside the decompression pin, with one end connected to the torsion spring mounting seat and the other end engaging with the decompression pin. A gasket is mounted on the camshaft body close to the outer end face of the decompression valve slinger. One end of the torsion spring is engaged with the camshaft body, and the other end is engaged with the decompression valve slinger. In this decompression valve, since both the slinger and the decompression pin need to rotate, effective lubrication is required to ensure smooth rotation. Currently, motorcycles primarily lubricate camshaft components such as the camshaft deflector and pressure relief pin through the lubricating oil mist formed inside the cylinder head during engine operation. However, this lubrication method is ineffective, making it difficult to ensure smooth rotation of the camshaft deflector and pressure relief pin. This leads to increased frictional resistance, causing wear and even seizing of the camshaft deflector and pressure relief pin, ultimately resulting in pressure relief failure. Therefore, existing motorcycle camshaft pressure relief structures suffer from insufficient operational stability. To improve the lubrication of camshaft components, fuel injectors are typically installed on the engine. These injectors spray lubricating oil through spray nozzles onto the required lubrication points, effectively lubricating camshaft components such as the camshaft deflector and pressure relief pin. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a lubrication structure for a motorcycle camshaft. The technical problem solved by this invention is how to improve the lubrication effect on the components on the camshaft and ensure that the camshaft decompression structure has high operational stability.

[0005] The objective of this invention can be achieved through the following technical solution: a lubrication structure for a motorcycle camshaft, the motorcycle including a cylinder head, a pressure reducing pin, a camshaft with an exhaust cam, and a sling block for driving the pressure reducing pin to rotate, characterized in that the lubrication structure includes an oil-drip protrusion disposed on the cylinder head, the side of the exhaust cam facing the sling block being a mounting surface and a boss portion integrally formed on the mounting surface, the oil-drip protrusion being disposed facing the boss portion and the boss portion being located below the oil-drip protrusion, an extension portion integrally formed on one side of the boss portion, an installation through hole being provided on the extension portion, an oil passage gap being formed between the extension portion and the mounting surface, one end of the sling block being connected to a pin inserted into the installation through hole, an installation notch being provided on the camshaft located on the other side of the boss portion, and the pressure reducing pin being disposed in the installation notch.

[0006] When the engine is running, oil mist forms inside the cylinder head, lubricating the camshaft, swashplate, and pressure relief pin. This lubrication structure utilizes drip protrusions on the cylinder head, allowing the oil mist to collect and condense. The lubricating oil on the protrusions then drips downwards onto the boss due to gravity. Simultaneously, since the camshaft rotates continuously during engine operation, and the oil passage clearance and mounting notch are located on the side of the boss, when the camshaft rotates to face upwards, the mounting notch or oil passage clearance will be below the drip protrusion.

[0007] When the mounting notch is located below the oil-drip protrusion, the lubricating oil on the protrusion can drip directly onto the pressure-reducing pin to lubricate it. Simultaneously, the mounting notch also has a certain oil-retention function, ensuring a sufficient amount of lubricating oil at the notch and guaranteeing good lubrication for the pressure-reducing pin. Similarly, when the oil passage gap is located below the oil-drip protrusion, the lubricating oil on the protrusion can also drip into the oil passage gap. This results in lubricating oil adhering to both sides of the extension, rather than just one side. The advantage of this is that the lubricating oil on both sides of the extension can enter the mounting through-hole from the two ports, ensuring good lubrication of the swing block and its pin, thus ensuring smooth swinging of the swing block.

[0008] Therefore, by setting the oil drip protrusion position and improving the camshaft structure itself, this lubrication structure can significantly improve the lubrication effect of the components on the camshaft at a lower cost, so that the swivel block and pressure relief pin can always rotate smoothly, ensuring that the motorcycle's camshaft pressure relief structure has high working stability.

[0009] In the above-mentioned lubrication structure of the motorcycle camshaft, the boss is flat and has two arc-shaped oil guiding surfaces located at its two ends. The mounting notch has a cutting plane perpendicular to the mounting surface of the exhaust cam. The edges of the two oil guiding surfaces near the mounting notch are in contact with the cutting plane.

[0010] The lubricating oil on the dripping protrusion can drip onto the first oil guide surface. The first oil guide surface is arc-shaped, which facilitates the lubricating oil to slide down to both ends of the first oil guide surface. Since the edges of both first oil guide surfaces near the mounting notch are in contact with the cutting plane, some of the lubricating oil on the first oil guide surface can slide down to the cutting plane, thereby ensuring that there is a lot of lubricating oil at the mounting notch and ensuring that the pressure reducing pin has a good lubrication effect.

[0011] In the aforementioned lubrication structure of the motorcycle camshaft, the edge of the extension has two symmetrically arranged arc-shaped oil guide surfaces, one of which smoothly transitions to its adjacent oil guide surface, and the other of which also smoothly transitions to its adjacent oil guide surface. This design not only ensures ease of machining but also allows the lubricating oil on both oil guide surfaces to flow smoothly toward the pressure reducing pin or shaft, improving the fluidity and lubrication efficiency of the lubricating oil, thereby enhancing the lubrication effect on the pressure reducing pin and the sling.

[0012] In the aforementioned lubrication structure of the motorcycle camshaft, the oil-drip protrusion is elongated, extending along the length of the camshaft. The lower edge of the protrusion is inclined, and the lower end of the lower edge forms a pointed tip. The boss is located below the pointed tip. The elongated structure allows the oil-drip protrusion to have a large surface area, enabling it to adhere to a significant amount of lubricating oil. Because the lower edge is inclined, the lubricating oil slides down the inclined lower edge to the pointed tip, with most of the oil dripping downwards from the pointed tip. This ensures that a large amount of lubricating oil drips into the boss, effectively lubricating the pressure-reducing pins and the pins on the swivel blocks on both sides of the boss.

[0013] In the above-mentioned lubrication structure of the motorcycle camshaft, the camshaft includes a shaft body, on which an annular positioning groove is provided circumferentially. The groove wall of the annular positioning groove near the boss is connected to the side wall of the boss facing away from the mounting surface. The annular positioning groove is also located below the oil drip protrusion. A torsion spring for driving the swing block to swing inward and reset is sleeved on the pin shaft. One end of the torsion spring is inserted into the swing block, and the other end of the torsion spring is located in the annular positioning groove.

[0014] The oil-drip protrusion is elongated, allowing lubricant to drip not only from its tip but also from other parts. Since the annular locating groove is located below the protrusion, lubricant from the protrusion also drips into it, acting as an oil reservoir. Because the other end of the torsion spring is located within the annular locating groove, when the camshaft rotates, the lubricant in the groove is propelled outwards by centrifugal force to the spring's main body, which is the part fitted onto the pin. This combination of the torsion spring and the annular locating groove further enhances the lubrication of the pin and the sway block, ensuring stable swaying of the sway block. Furthermore, the annular locating groove confines the other end of the torsion spring within it, guaranteeing its positional accuracy and allowing it to stably drive the sway block to its reset position.

[0015] In the aforementioned lubrication structure of the motorcycle camshaft, an intake cam is integrally formed on the shaft. The cylinder head has two opposing support frames, namely, support frame one and support frame two. The two ends of the shaft are rotatably mounted on support frame one and support frame two, respectively. The intake cam and exhaust cam are located between support frame one and support frame two, with support frame one positioned closer to the exhaust cam. By providing support frame one and support frame two, the two ends of the camshaft are supported, ensuring smooth and stable rotation of the camshaft.

[0016] In the aforementioned lubrication structure for a motorcycle camshaft, this motorcycle also includes an intake rocker arm shaft and an intake valve rocker arm mounted on the intake rocker arm shaft. The support frame one has a cylindrical sleeve portion on its side facing the support frame two. The support frame two has mounting holes directly opposite the sleeve portion. Both ends of the intake rocker arm shaft are respectively inserted into the sleeve portion and the mounting holes. The oil drip protrusion is integrally formed on the bottom surface of the sleeve portion. The sleeve portion design not only improves the positioning effect of the intake rocker arm shaft end and enhances the installation stability of the intake rocker arm shaft, but also provides a larger forming area for the oil drip protrusion, facilitating the formation of a sufficiently long oil drip protrusion, thereby improving the lubrication effect of the device through the use of the elongated oil drip protrusion.

[0017] In the aforementioned lubrication structure for a motorcycle camshaft, the upper surface of the oil-drip protrusion is a convex arc surface, and the lower surface is a concave arc surface. The convex upper surface ensures that the lubricating oil flows smoothly downwards to the lower edge of the protrusion, while the concave lower surface makes it difficult for the lubricating oil to flow from the lower edge to the lower surface of the protrusion. This results in a larger amount of lubricating oil forming at the lower edge of the protrusion, thus ensuring a greater oil drip volume and improving the lubrication effect of the device.

[0018] In the aforementioned lubrication structure of the motorcycle camshaft, the exhaust cam has a connecting hole located on the outer side of the cutting plane, and the pressure reducing pin is inserted into the connecting hole. This design facilitates the installation of the pressure reducing pin. When the camshaft rotates, the lubricating oil in the mounting notch flows outward due to centrifugal force, allowing the lubricating oil to enter the connecting hole and fully lubricate the pressure reducing pin, ensuring that the pressure reducing pin can always rotate stably.

[0019] In the aforementioned lubrication structure for a motorcycle camshaft, a mounting plate is fitted onto the camshaft shaft. The mounting plate has pin holes, and both ends of the pin are respectively inserted into the mounting through hole and the pin hole. By setting the mounting plate, both ends of the pin are supported, ensuring good installation stability for the pin and the slinger mounted on it. This results in high operational stability for the pressure-reducing structure.

[0020] Compared with existing technologies, the lubrication structure of this motorcycle camshaft has the following advantages:

[0021] 1. This lubrication structure, through the setting of the oil drip protrusion and the improvement of the camshaft structure itself, can significantly improve the lubrication effect of the components on the camshaft, so that the swashplate and pressure relief pin can always rotate smoothly, ensuring that the motorcycle's camshaft pressure relief structure has high working stability.

[0022] 2. This lubrication structure also has the advantage of low improvement cost, making it suitable for widespread use. Attached Figure Description

[0023] Figure 1 This is a front view of the motorcycle cylinder head.

[0024] Figure 2 This is a three-dimensional structural diagram of the camshaft assembly.

[0025] Figure 3 This is an exploded view of the camshaft assembly.

[0026] Figure 4 This is a top view of the motorcycle cylinder head area.

[0027] Figure 5 yes Figure 4 Enlarged view of point a in the middle.

[0028] Figure 6 yes Figure 4 A partial sectional view of AA.

[0029] Figure 7 This is a structural diagram of a part of the cylinder head support frame.

[0030] Figure 8This is a three-dimensional structural diagram of a camshaft.

[0031] Figure 9 This is a front view of the camshaft.

[0032] Figure 10 This is a schematic diagram of a partial structure of a motorcycle.

[0033] In the diagram, 1. Cylinder head; 1a. Support frame one; 1a1. Sleeve part; 1b. Support frame two; 1b1. Mounting hole; 2. Pressure reducing pin; 3. Camshaft; 31. Exhaust cam; 31a. Mounting surface; 31b. Connecting hole; 32. Boss part; 321. Oil guide surface one; 33. Extension part; 331. Oil guide surface two; 34. Mounting through hole; 35. Oil passage clearance; 36. Mounting notch; 361. Cutting plane; 37. Shaft body; 371. Annular positioning groove; 38. Intake cam; 4. Thruster; 5. Oil drip protrusion; 51. Pointed head; 6. Pin shaft; 7. Torsion spring; 8. Intake rocker arm shaft; 9. Intake valve rocker arm; 10. Mounting plate; 101. Pin hole; 11. Exhaust valve rocker arm; 12. Bearing. Detailed Implementation

[0034] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0035] like Figure 1 , Figure 2 and Figure 3 As shown, the motorcycle includes a cylinder head 1, a pressure relief pin 2, a camshaft 3 with an exhaust cam 31, and a sling block 4 for rotating the pressure relief pin 2. The lubrication structure of the camshaft 3 of this motorcycle includes an oil dripping protrusion 5 provided on the cylinder head 1. The side of the exhaust cam 31 facing the sling block 4 is a mounting surface 31a, and a boss portion 32 is integrally formed on the mounting surface 31a. The oil dripping protrusion 5 is positioned facing the boss portion 32, and the boss portion 32 is located below the oil dripping protrusion 5. An extension portion 33 is integrally formed on one side of the boss portion 32. An installation through hole 34 is provided on the extension portion 33. An oil passage gap 35 is formed between the extension portion 33 and the mounting surface 31a. One end of the sling block 4 is connected to a pin 6 inserted into the installation through hole 34. An installation notch 36 is provided on the camshaft 3 on the other side of the boss portion 32, and the pressure relief pin 2 is provided in the installation notch 36. Furthermore, a mounting plate 10 and a bearing 12 are also fitted onto the shaft body 37 of the camshaft 3. The bearing 12 is used to support the camshaft 3 and can fix the mounting plate 10. The mounting plate 10 has a pin hole 101, and the two ends of the pin 6 are respectively inserted into the mounting through hole 34 and the pin hole 101.

[0036] like Figure 2As shown, the camshaft 3 includes a shaft body 37, on which an intake cam 38 is integrally formed. An annular positioning groove 371 is provided on the shaft body 37 along the circumferential direction. The groove wall of the annular positioning groove 371 near the boss part 32 is connected to the side wall of the boss part 32 facing away from the mounting surface 31a. The annular positioning groove 371 is also located below the oil drip protrusion 5. A torsion spring 7 is sleeved on the pin 6 to drive the swing block 4 to swing inward for reset. One end of the torsion spring 7 is inserted into the swing block 4, and the other end of the torsion spring 7 is located in the annular positioning groove 371.

[0037] like Figures 4 to 7 As shown, the oil-drip protrusion 5 is elongated, with its upper surface being a convex arc and its lower surface a concave arc. The length of the oil-drip protrusion 5 extends along the length of the camshaft 3. The lower edge of the oil-drip protrusion 5 is inclined, and the lower end of the lower edge forms a pointed head 51. The boss portion 32 is located below the pointed head 51 of the oil-drip protrusion 5. Lubricating oil on the oil-drip protrusion 5 slides down the inclined lower edge to the pointed head 51, with most of the lubricating oil dripping down from the pointed head 51, ensuring that a large amount of lubricating oil drips into the boss portion 32.

[0038] Figure 1 and Figure 6 In this diagram, the Z-axis represents the direction perpendicular to the horizontal plane.

[0039] like Figure 8 and Figure 9 As shown, the boss portion 32 is flat and roughly rectangular. It has two arc-shaped oil-guiding surfaces 321 at its two ends. The mounting notch 36 has a cutting plane 361 perpendicular to the mounting surface 31a of the exhaust cam 31. The edges of both oil-guiding surfaces 321 near the mounting notch 36 are in contact with the cutting plane 361. The exhaust cam 31 has a connecting hole 31b located outside the cutting plane 361, into which the pressure-reducing pin 2 is inserted. This design allows some of the lubricating oil on the oil-guiding surfaces 321 to slide down onto the cutting plane 361, thus ensuring sufficient lubricating oil at the mounting notch 36 and providing good lubrication for the pressure-reducing pin 2.

[0040] like Figure 8 and Figure 9 As shown, the edge of the extension 33 has two symmetrically arranged arc-shaped oil guiding surfaces 331. One oil guiding surface 331 is smoothly connected to the adjacent oil guiding surface 321, and the other oil guiding surface 331 is also smoothly connected to the adjacent oil guiding surface 321. This design allows the lubricating oil on the oil guiding surfaces 321 and 331 to flow smoothly toward the pressure reducing pin 2 or the pin shaft 6, improving the fluidity and lubrication efficiency of the lubricating oil, thereby improving the lubrication effect of the pressure reducing pin 2 and the sling block 4.

[0041] like Figure 7 and Figure 10 As shown, the cylinder head 1 has two opposing support frames 1a and 1b. The two ends of the shaft 37 are rotatably mounted on the support frames 1a and 1b, respectively. The intake cam 38 and the exhaust cam 31 are located between the support frames 1a and 1b, with the support frame 1a positioned close to the exhaust cam 31. This motorcycle also includes an intake rocker arm shaft 8 and an intake valve rocker arm 9 mounted on the intake rocker arm shaft 8. The side of the support frame 1a facing the support frame 1b has a cylindrical sleeve portion 1a1. The support frame 1b has a mounting hole 1b1 facing the sleeve portion 1a1. The two ends of the intake rocker arm shaft 8 are inserted into the sleeve portion 1a1 and the mounting hole 1b1, respectively. The oil drip protrusion 5 is integrally formed on the bottom surface of the sleeve portion 1a1.

[0042] When the engine is running, oil mist forms inside the cylinder head, which lubricates the camshaft 3, the swashplate 4, and the pressure relief pin 2. Based on this, the lubrication structure incorporates an oil-drip protrusion 5 on the cylinder head 1. The oil mist collects and condenses at the protrusion 5, and the lubricating oil on the protrusion 5 drips downwards onto the boss portion 32 due to its own gravity. Simultaneously, since the camshaft 3 is constantly rotating during engine operation, and the oil passage clearance 35 and the mounting notch 36 are located on the side of the boss portion 32, when the camshaft 3 rotates to the point where the mounting notch 36 or the oil passage clearance 35 faces upwards, the mounting notch 36 or the oil passage clearance 35 will be below the oil-drip protrusion 5.

[0043] When the mounting notch 36 is located below the oil-drip protrusion 5, the lubricating oil on the oil-drip protrusion 5 can drip directly onto the pressure-reducing pin 2 to lubricate it. Simultaneously, the mounting notch 36 also has a certain oil-retention function, resulting in a sufficient amount of lubricating oil at the mounting notch 36 to ensure good lubrication of the pressure-reducing pin 2. Similarly, when the oil passage gap 35 is located below the oil-drip protrusion 5, the lubricating oil on the oil-drip protrusion 5 can also drip into the oil passage gap 35. This ensures that lubricating oil adheres to both sides of the extension 33 instead of only one side. This allows the lubricating oil on both sides of the extension 33 to enter the mounting through hole 34 from its two ports, ensuring good lubrication of the swing block 4 and the pin 6 on it, thus ensuring smooth swinging of the swing block 4.

[0044] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0045] Although this article frequently uses terms such as 1. cylinder head; 1a. support frame one; 1a1. sleeve part; 1b. support frame two; 1b1. mounting hole; 2. pressure relief pin; 3. camshaft; 31. exhaust cam; 31a. mounting surface; 31b. connecting hole; 32. boss part; 321. oil guide surface one; 33. extension part; 331. oil guide surface two; 34. mounting through hole; 35. oil passage clearance; 36. mounting notch; 361. cutting plane; 37. shaft body; 371. annular positioning groove; 38. intake cam; 4. sling block; 5. oil drip protrusion; 51. pointed head; 6. pin shaft; 7. torsion spring; 8. intake rocker arm shaft; 9. intake valve rocker arm; 10. mounting plate; 101. pin hole; 11. exhaust valve rocker arm; 12. bearing, the possibility of using other terms cannot be excluded. The use of these terms is merely for the convenience of describing and explaining the nature of the invention; interpreting them as any additional limitation would be contrary to the spirit of the invention.

Claims

1. A lubrication structure for a motorcycle camshaft, the motorcycle comprising a cylinder head (1), a pressure relief pin (2), a camshaft (3) having an exhaust cam (31), and a swashplate (4) for rotating the pressure relief pin (2), characterized in that, This lubrication structure includes an oil-drip protrusion (5) on the cylinder head (1), the side of the exhaust cam (31) facing the slinger (4) is a mounting surface (31a) and a boss (32) is integrally formed on the mounting surface (31a), the oil-drip protrusion (5) is positioned facing the boss (32) and the boss (32) is located below the oil-drip protrusion (5), an extension (33) is integrally formed on one side of the boss (32), an installation through hole (34) is provided on the extension (33), an oil passage gap (35) is formed between the extension (33) and the mounting surface (31a), one end of the slinger (4) is connected to a pin (6) inserted into the installation through hole (34), an installation notch (36) is provided on the camshaft (3) on the other side of the boss (32), and a pressure-reducing pin (2) is provided in the installation notch (36).

2. The lubrication structure for the motorcycle camshaft according to claim 1, characterized in that, The boss portion (32) is flat and has two arc-shaped oil guide surfaces (321) located at its two ends. The mounting notch (36) has a cutting plane (361) perpendicular to the mounting surface (31a) of the exhaust cam (31). The edges of the two oil guide surfaces (321) near the mounting notch (36) are in contact with the cutting plane (361).

3. The lubrication structure for the motorcycle camshaft according to claim 2, characterized in that, The edge of the extension (33) has two symmetrically arranged arc-shaped oil guiding surfaces (331), one of which is smoothly connected to the adjacent oil guiding surface (321), and the other is smoothly connected to the adjacent oil guiding surface (321).

4. The lubrication structure for a motorcycle camshaft according to claim 1, 2, or 3, characterized in that, The oil-dripping protrusion (5) is elongated and extends along the length of the camshaft (3). The lower edge of the oil-dripping protrusion (5) is inclined and a pointed head (51) is formed at the lower end of the lower edge of the oil-dripping protrusion (5). The boss (32) is located below the pointed head (51) of the oil-dripping protrusion (5).

5. The lubrication structure for a motorcycle camshaft according to claim 1, 2, or 3, characterized in that, The camshaft (3) includes a shaft body (37), on which an annular positioning groove (371) is provided along the circumference. The groove wall of the annular positioning groove (371) near the boss (32) is connected to the side wall of the boss (32) facing away from the mounting surface (31a). The annular positioning groove (371) is also located below the oil drip protrusion (5). A torsion spring (7) for driving the swing block (4) to swing inward for reset is sleeved on the pin (6). One end of the torsion spring (7) is inserted into the swing block (4), and the other end of the torsion spring (7) is located in the annular positioning groove (371).

6. The lubrication structure for a motorcycle camshaft according to claim 5, characterized in that, An intake cam (38) is integrally formed on the shaft (37). The cylinder head (1) has two opposing support frames (1a and 1b). The two ends of the shaft (37) are respectively rotatably mounted on the support frames (1a) and the support frames (1b). The intake cam (38) and the exhaust cam (31) are located between the support frames (1a) and the support frames (1b), and the support frame (1a) is positioned close to the exhaust cam (31).

7. The lubrication structure for a motorcycle camshaft according to claim 6, characterized in that, This motorcycle also includes an intake rocker arm shaft (8) and an intake valve rocker arm (9) mounted on the intake rocker arm shaft (8). The support frame one (1a) has a cylindrical sleeve portion (1a1) on its side facing the support frame two (1b). The support frame two (1b) has a mounting hole (1b1) that is directly opposite to the sleeve portion (1a1). The two ends of the intake rocker arm shaft (8) are respectively inserted into the sleeve portion (1a1) and the mounting hole (1b1). The oil drip protrusion (5) is integrally formed on the bottom surface of the sleeve portion (1a1).

8. The lubrication structure for a motorcycle camshaft according to claim 1, 2, or 3, characterized in that, The upper side of the oil-dripping protrusion (5) is an outwardly convex arc surface and the lower side is an inwardly concave arc surface.

9. The lubrication structure for a motorcycle camshaft according to claim 2 or 3, characterized in that, The exhaust cam (31) has a connecting hole (31b) located outside the cutting plane (361), and the pressure reducing pin (2) is inserted into the connecting hole (31b).

10. The lubrication structure for a motorcycle camshaft according to claim 5, characterized in that, The camshaft (3) is also fitted with a mounting plate (10), and the mounting plate (10) has a pin hole (101). The two ends of the pin (6) are respectively inserted into the mounting through hole (34) and the pin hole (101).

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