An oil cooling structure for a motorcycle engine

Abstract

This utility model belongs to the technical field of motorcycle parts, and relates to an oil cooling structure for a motorcycle engine. It includes a crankcase, in which a crankshaft is housed and filled with engine oil. One end of the crankshaft extends out of the crankcase and is fitted with a fan. The fan is covered by a fan shroud, the outer end of which has an axial air inlet and a circumferential air outlet on its side wall. Several cooling fins are arranged on the side of the crankcase near the fan shroud. The inner side of the cooling fins contacts the engine oil and transfers heat, while the outer side is covered by a radial extension of the fan shroud. An air outlet communicating with the air outlet is provided on the radial extension of the fan shroud. The oil cooling structure for a motorcycle engine provided by this utility model can significantly improve the oil cooling effect of the engine.

Description

Technical Field

[0001] This utility model belongs to the technical field of motorcycle parts and relates to an oil cooling structure for a motorcycle engine. Background Technology

[0002] An air-cooled engine is an engine that uses air as the cooling medium. It has cooling fins cast into the outer walls of the cylinder and cylinder head, and a cooling fan blows air at high speed across the surface of these fins, carrying away the heat dissipated by the engine and cooling it down. Air-cooled engines are a type of engine characterized by their simple structure and light weight. They are easy to maintain and use, highly adaptable to climate changes, quick to start, and do not require a radiator, making them widely used in motorcycles.

[0003] However, traditional air-cooled engines have limited coverage. Chinese utility model patent application CN119435189A (publication date: 2025.02.14) discloses an air-cooling system and engine, including an engine block and a cooling system. The cooling system includes a fan assembly, including a fan and a fan shroud with an air outlet I; an air guide shroud for forming a cooling air duct for cooling the engine block, the cooling air duct being connected to the air outlet I; and a flow guide, disposed within the cooling air duct, for forming a branch air duct for diverting and guiding the cooling air to the area near the intake side of the cylinder head spark plug I. The air-cooling system and engine of this utility model, with the air guide shroud connected to the fan shroud, form a cooling air duct for cooling the cylinder block and cylinder head, achieving sufficient cooling of the cylinder block and cylinder head. At the same time, by setting the flow guide, the cooling air is guided to the spark plug area of ​​the cylinder head, which can improve the cooling effect on the spark plug, increase the utilization rate of the cooling air, and make the heat dissipation of various engine components uniform, thereby meeting the requirements of engine power, economy and reliability.

[0004] The aforementioned structure directs cooling air to the cylinder block and cylinder head, expanding the coverage of the air-cooled system, especially for cooling the spark plug area. However, the engine oil in the crankcase lacks a cooling structure, resulting in poor cooling performance, and prolonged exposure to high temperatures negatively impacts oil performance. Utility Model Content

[0005] This invention addresses the shortcomings of existing technologies by providing an oil cooling structure for a motorcycle engine, which can significantly improve the oil cooling effect of the engine.

[0006] To solve the above-mentioned technical problems, the objective of this utility model is achieved through the following technical solution:

[0007] An oil cooling structure for a motorcycle engine includes a crankcase containing a crankshaft and storing oil. One end of the crankshaft extends out of the crankcase and is fitted with a fan. The fan is covered by a fan shroud, with an axial air inlet at its outer end and a circumferential air outlet on its side wall. Several cooling fins are provided on the side of the crankcase near the fan shroud. The inner side of the cooling fins contacts the oil and transfers heat, while the outer side is covered by a radial extension of the fan shroud. An air outlet communicating with the air outlet is provided on the radial extension of the fan shroud.

[0008] In the above-mentioned oil cooling structure for a motorcycle engine, the inner side of the heat dissipation fin forms a curved heat-conducting surface, and the outer side forms a heat dissipation air guide groove with an arc-shaped bottom. The air outlet is provided in a one-to-one correspondence with the heat dissipation air guide groove, and the cooling airflow from the air outlet flows along the heat dissipation air guide groove and the air outlet.

[0009] In the aforementioned oil cooling structure for a motorcycle engine, an outward-facing arc-shaped boss is provided at the bottom of the crankcase on the side away from the cylinder block. The arc-shaped boss forms the base structure for the heat dissipation fins. The heat dissipation air guide groove connects the outer side of the arc-shaped boss and the opposite side of the arc-shaped boss and the crankshaft. The outer side of the arc-shaped boss refers to its axial outer side, and the opposite side of the arc-shaped boss and the crankshaft refers to its radial inner side.

[0010] In the aforementioned oil cooling structure for a motorcycle engine, the cooling fins are integrally formed with the crankcase.

[0011] In the aforementioned oil cooling structure for a motorcycle engine, the heat dissipation fins include a plurality of spaced-apart fins, with heat dissipation air ducts formed between adjacent fins. A concave heat-conducting surface is formed on the inner side of each fin, and a convex heat-conducting surface is formed on the inner side of each heat dissipation air duct. In this invention, the fins are three-dimensional fins, distinct from traditional sheet-like fins. The three-dimensional fins have a considerable width, sufficient to form a curved heat-conducting surface on the corresponding back side.

[0012] In the above-mentioned oil cooling structure for a motorcycle engine, preferably, the coverage range of the arc-shaped boss is 45°-90°.

[0013] In the above-mentioned oil cooling structure for a motorcycle engine, two air outlets are provided, one of which is connected to the air outlet hole, and the other is connected to the cylinder head through a guide shroud. Furthermore, the guide shroud gradually converges along the airflow direction and enters the cylinder head from the spark plug. The gaps on both sides of the spark plug form an air intake channel, the gaps on both sides of the air intake port form an air intake side exhaust channel, and the gaps on both sides of the exhaust port form an exhaust side exhaust channel.

[0014] Compared with the prior art, this utility model has the following advantages:

[0015] This invention provides an oil cooling structure for a motorcycle engine, addressing the problem of insufficient oil cooling in the crankcase by designing an independent cooling path and a heat dissipation fin structure. Airflow is guided through the fan shroud's outlet to a radial extension, covering the heat dissipation fins on one side of the crankcase. The inner side of the heat dissipation fins exchanges heat efficiently with the oil via a curved heat-conducting surface. The outer airflow flows through a cooling air guide channel and exits through the outlet, carrying away the heat exchanged by the heat dissipation fins. This effectively reduces the oil temperature, preventing the long-term effects of high temperatures on oil performance and ensuring the reliability of the lubrication system. The unique heat dissipation fin structure of this invention ensures excellent heat exchange efficiency on both the inner and outer sides. Attached Figure Description

[0016] Figure 1 This is a perspective view of the present invention;

[0017] Figure 2 This is a perspective view of the present invention (with the fan cover and air guide cover removed);

[0018] Figure 3 This is a perspective view of the fan cover and air guide cover of this utility model;

[0019] Figure 4 This is a perspective view of the crankcase of this utility model;

[0020] Figure 5 This is another perspective view of the crankcase of this utility model;

[0021] Reference numerals: 1. Crankcase; 2. Crankshaft; 3. Fan; 4. Fan shroud; 5. Air inlet; 6. Air outlet; 7. Cooling fin; 8. Radial extension; 9. Air outlet; 10. Heat-conducting surface; 11. Heat dissipation duct; 12. Cylinder block; 13. Arc-shaped boss; 14. Fin; 15. Concave heat-conducting surface; 16. Convex heat-conducting surface; 17. Air guide shroud; 18. Cylinder head. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. See also: Figure 1-5 :

[0023] An oil cooling structure for a motorcycle engine includes a crankcase 1, a crankshaft 2 housed within the crankcase 1 and storing oil, one end of the crankshaft 2 extending out of the crankcase 1 and fitted with a fan 3, the fan 3 being covered by a fan shroud 4, the outer end of the fan shroud 4 having an axial air inlet 5 and a circumferential air outlet 6 on its side wall, a plurality of cooling fins 7 being provided on the side of the crankcase 1 near the fan shroud 4, the inner side of the cooling fins 7 contacting the oil and transferring heat, the outer side being covered by a radial extension 8 of the fan shroud 4, and the radial extension 8 of the fan shroud 4 having an air outlet 9 communicating with the air outlet 6.

[0024] Furthermore, the specific structure of the heat dissipation fin 7 in this embodiment is as follows: the inner side of the heat dissipation fin 7 forms a curved heat-conducting surface 10, and the outer side forms a heat dissipation airflow channel 11 with an arc-shaped bottom. The air outlet 9 is arranged in a one-to-one correspondence with the heat dissipation airflow channel 11, and the cooling airflow of the air outlet 6 flows along the heat dissipation airflow channel 11 and the air outlet 9. Specifically, the heat dissipation fin 7 includes a plurality of spaced fins 14, with heat dissipation airflow channels 11 formed between adjacent fins 14. The inner side of the fin 14 forms a concave heat-conducting surface 15, and the inner side of the heat dissipation airflow channel 11 forms a convex heat-conducting surface 16. The concave heat-conducting surface 15 and the convex heat-conducting surface 16 together form a curved heat-conducting surface 10. In this utility model, the fin 14 is a three-dimensional fin 14, which is different from the traditional sheet-like fin 14. The three-dimensional fin 14 has a considerable width, which is sufficient to form a curved heat-conducting surface 10 on the corresponding part of the back side.

[0025] In this embodiment, after the motorcycle engine starts, the crankshaft 2 drives the fan 3 at one end to rotate at high speed. The cooling airflow generated by the fan 3 (the low-temperature gas from the outside enters through the axial air inlet 5 at the end of the fan cover 4 to form the cooling airflow) is constrained and diverted by the fan cover 4. Part of the airflow enters the radial extension 8 through the air outlet 6. This airflow is guided to the surface of the heat dissipation fins 7 on the side wall of the crankcase 1. The airflow flows along the heat dissipation guide groove 11 formed by adjacent fins 14. The airflow contacts both the fins 14 and the heat dissipation guide groove 11 to exchange heat efficiently. At the same time, the curved heat-conducting surface 10 (which has a larger heat exchange area) on the inner side of the heat dissipation fins 7 (facing the inside of the crankcase 1) exchanges heat efficiently with the engine oil in the case, absorbing the heat from the engine oil. The airflow carrying the heat is finally discharged through the air outlet 9 at the end, achieving continuous forced air cooling of the engine oil.

[0026] The specific structure of the aforementioned three-dimensional heat dissipation fin array 7 is as follows: An outward-facing arc-shaped boss 13 is provided at the bottom of the crankcase 1 on the side away from the cylinder block 12. The arc-shaped boss 13 forms the base structure of the heat dissipation fins 7. The heat dissipation air guide groove 11 connects the outer side of the arc-shaped boss 13 and the opposite surface of the arc-shaped boss 13 to the crankshaft 2. The outer side of the arc-shaped boss 13 refers to its axial outer side, and the opposite surface of the arc-shaped boss 13 to the crankshaft 2 refers to its radial inner side. By setting the arc-shaped boss 13, the axial distance between the three-dimensional fins 14 and the cooling airflow can be extended, significantly enhancing the heat dissipation effect.

[0027] The aforementioned heat dissipation fin 7 is integrally formed with the crankcase 1. The heat dissipation fin 7 is formed by stamping or integral casting based on the crankcase 1.

[0028] The arc-shaped boss 13 has a coverage range of 45°-90°. This range can avoid interference with other structures of the crankcase 1 and also has sufficient heat exchange area.

[0029] In this embodiment, two air outlets 6 are provided. One is connected to the air outlet 9, and the other is connected to the cylinder head 18 via a guide shroud 17. Furthermore, the guide shroud 17 gradually converges along the airflow direction and enters the cylinder head 18 through the spark plug. The gaps on both sides of the spark plug form an intake airflow channel, the gaps on both sides of the intake port form an intake-side exhaust airflow channel, and the gaps on both sides of the exhaust port form an exhaust-side exhaust airflow channel. By splitting the cooling airflow, the oil side of the crankcase 1 and the cylinder head 18 can be cooled separately.

[0030] The above embodiments are merely preferred embodiments of the present utility model and are not intended to limit the scope of protection of the present utility model. Therefore, all equivalent changes made to the structure, shape, and principle of the present utility model should be covered within the scope of protection of the present utility model.

Claims

1. An oil cooling structure for a motorcycle engine, comprising a crankcase (1), wherein a crankshaft (2) is disposed within the crankcase (1) and stores oil, one end of the crankshaft (2) extends through the crankcase (1) and is fitted with a fan (3), the fan (3) is covered by a fan shroud (4), the outer end of the fan shroud (4) is provided with an axial air inlet (5), and the side wall is provided with a circumferential air outlet (6), characterized in that, The crankcase (1) is provided with several heat dissipation fins (7) on the side near the fan cover (4). The inner side of the heat dissipation fins (7) is in contact with the engine oil and transfers heat, while the outer side is covered by the radial extension (8) of the fan cover (4). The radial extension (8) of the fan cover (4) is provided with an air outlet (9) that communicates with the air outlet (6).

2. The oil cooling structure for a motorcycle engine according to claim 1, characterized in that, The inner side of the heat dissipation fin (7) forms a curved heat-conducting surface (10), and the outer side forms a heat dissipation air guide groove (11) with an arc bottom. The air outlet (9) is arranged in a one-to-one correspondence with the heat dissipation air guide groove (11), and the cooling airflow of the air outlet (6) flows along the heat dissipation air guide groove (11) and the air outlet (9).

3. The oil cooling structure for a motorcycle engine according to claim 2, characterized in that, The crankcase (1) has an outward-facing arc-shaped boss (13) at the bottom of the side away from the cylinder block (12). The arc-shaped boss (13) forms the base structure of the heat dissipation fin (7). The heat dissipation duct (11) connects the outer side of the arc-shaped boss (13) and the opposite side of the arc-shaped boss (13) and the crankshaft (2).

4. The oil cooling structure for a motorcycle engine according to claim 3, characterized in that, The heat dissipation fins (7) are integrally formed with the crankcase (1).

5. The oil cooling structure for a motorcycle engine according to claim 4, characterized in that, The heat dissipation fin (7) includes a number of spaced fins (14), and a heat dissipation duct (11) is formed between adjacent fins (14). A concave heat-conducting surface (15) is formed on the inner side of the fin (14), and a convex heat-conducting surface (16) is formed on the inner side of the heat dissipation duct (11).

6. The oil cooling structure for a motorcycle engine according to claim 3, characterized in that, The arc-shaped boss (13) has a coverage range of 45°-90°.

7. The oil cooling structure for a motorcycle engine according to claim 1, characterized in that, The air outlet (6) is provided in two parts, one of which is connected to the air outlet (9), and the other is connected to the cylinder head (18) through the air guide shroud (17).

Images