Cylinder head structure of motorcycle engine

Abstract

The utility model belongs to the technical field of motorcycle engines, and relates to an air cylinder head structure of a motorcycle engine, which comprises an air cylinder head, a cam shaft is arranged at the top of the air cylinder head, a timing chain wheel is sleeved on the cam shaft, a combustion chamber is arranged below the cam shaft, and a decompression ejector rod for ejecting an exhaust valve open is arranged in the cam shaft in a sliding mode. A centrifugal mechanism for driving the decompression ejector rod to slide is arranged on the timing chain wheel, a first sparking plug and a second sparking plug which are inclined are arranged on the left side and the right side of the combustion chamber respectively, and the included angle between the second sparking plug and the bottom plane of the air cylinder head is smaller than that between the first sparking plug and the bottom plane of the air cylinder head. The air cylinder head is provided with an avoiding groove for avoiding the timing chain wheel and a sleeve base extending in the direction of the avoiding groove, and a sleeve for installing a second spark plug is arranged in the sleeve base. The cylinder head structure of the motorcycle engine is compact in layout, stable in structure and capable of achieving the purpose of further saving energy and reducing consumption.

Description

Technical Field

[0001] This utility model belongs to the technical field of motorcycle engines, and relates to a cylinder head structure for a motorcycle engine. Background Technology

[0002] The cylinder head of a conventional motorcycle engine typically houses a camshaft, intake assembly, exhaust assembly, and combustion system. The camshaft is located at the top center of the cylinder head, with the intake and exhaust assemblies positioned on either side of it. The camshaft works in conjunction with the intake and exhaust assemblies to control their movement, thereby completing the intake and exhaust processes after combustion.

[0003] During operation, the combustion system requires an air-fuel ratio (A / F) of approximately 14.8:1, and the instantaneous operating temperature is much lower. This results in incomplete combustion of fuel, low thermal efficiency, and high levels of exhaust pollutants. Furthermore, motorcycle engines require the intake of fresh air for compression during startup. Significant compression resistance is generated near the end of this compression phase. Without decompression, this increases starting force, making starting extremely difficult. Therefore, a high-power starter motor is necessary. Both of these factors contribute to the low efficiency and high energy consumption of motorcycle engines.

[0004] To address the low thermal efficiency of combustion systems, some motorcycle engine cylinder heads have been modified from a single spark plug structure to a dual spark plug structure. For example, Chinese Utility Model Patent CN2830691Y (publication date: October 25, 2006) discloses a dual spark plug ignition cylinder head for a single-cylinder gasoline engine in a motorcycle. To address the issue of high starter motor power in motorcycle engines, some motorcycle engine cylinder heads are equipped with a pressure relief mechanism. For instance, Chinese Utility Model Patent CN221856841U (publication date: October 18, 2024) discloses an engine with a pressure relief mechanism.

[0005] In practical engine design, installing dual spark plugs requires sufficient cylinder wall thickness in the cylinder head, thus necessitating adherence to the axial dimensions of the cylinder walls. Furthermore, installing a decompression mechanism increases the axial dimensions of the camshaft and timing sprocket, requiring more axial clearance in the cylinder head. Therefore, designing both a dual spark plug ignition structure and a decompression mechanism while maintaining the basic dimensions of the engine cylinder head is extremely challenging. Utility Model Content

[0006] This utility model addresses the shortcomings of existing technologies by providing a cylinder head structure for a motorcycle engine. This structure is compact and robust, and can further achieve the goal of energy saving and consumption reduction.

[0007] To solve the above-mentioned technical problems, the objective of this utility model is achieved through the following technical solution:

[0008] A cylinder head structure for a motorcycle engine includes a cylinder head, a camshaft mounted on the top of the cylinder head, a timing sprocket mounted on the camshaft, an intake assembly and an exhaust assembly mounted on the front and rear sides of the camshaft, a combustion chamber located below the camshaft, a pressure relief pushrod slidingly within the camshaft to open the exhaust valve, a centrifugal mechanism mounted on the timing sprocket to drive the pressure relief pushrod to slide, and an inclined first spark plug and a second spark plug respectively mounted on the left and right sides of the combustion chamber, the angle between the second spark plug and the bottom plane of the cylinder head being smaller than the angle between the first spark plug and the bottom plane of the cylinder head, a clearance groove for avoiding the timing sprocket and a sleeve seat extending towards the clearance groove on the cylinder head, and a sleeve for installing the second spark plug located within the sleeve seat.

[0009] In the above-mentioned cylinder head structure of a motorcycle engine, the angle between the first spark plug and the bottom plane of the cylinder head is 52.5°-57.5°; the angle between the second spark plug and the bottom plane of the cylinder head is 23.5°-26.5°; preferably, the angle between the first spark plug and the bottom plane of the cylinder head is 55°; and the angle between the second spark plug and the bottom plane of the cylinder head is 25°.

[0010] In the cylinder head structure of the motorcycle engine described above, the sleeve is inclined from the inside to the outside towards the exhaust assembly, and the angle between the sleeve and the vertical plane of the camshaft axis is 7.5°-8.5°; preferably, the angle between the sleeve and the vertical plane of the camshaft axis is 8°.

[0011] In the cylinder head structure of the motorcycle engine described above, the sleeve seat extends outward from the cylinder wall inside the clearance groove and protrudes out of the plane where the cylinder wall is located. The end of the sleeve is inserted into the sleeve seat and sealed.

[0012] In the cylinder head structure of the motorcycle engine described above, the intake assembly includes an intake port with an intake mounting surface, which is connected to an intake pipe via fasteners; the exhaust assembly includes an exhaust port with an exhaust mounting surface, which is connected to a muffler via fasteners; the muffler is a common type used in the art.

[0013] In the aforementioned cylinder head structure of a motorcycle engine, the centrifugal mechanism includes a unidirectional centrifugal counterweight hinged to the timing sprocket. This unidirectional centrifugal counterweight is driven by centrifugal force, causing the decompression shaft to rotate. The decompression shaft, through an eccentric mechanism, drives a decompression push rod to slide. Further, the unidirectional centrifugal counterweight is connected to the decompression shaft via a pin and a fork. The eccentric mechanism includes an eccentric drive block at the end of the decompression shaft and a drive groove on the decompression push rod that mates with the drive block. Preferably, the decompression push rod is arranged radially, the drive shaft is arranged axially, and the unidirectional centrifugal counterweight is arranged parallel to the timing sprocket.

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

[0015] 1. This utility model provides a cylinder head structure for a motorcycle engine, employing a dual spark plug ignition structure and a starting decompression structure. Dual spark plug ignition shortens the flame propagation distance within the combustion chamber and generates a stronger vortex, accelerating flame propagation and significantly improving heat utilization. The starting decompression structure reduces the power of the starter motor, thereby significantly lowering starting energy consumption. This utility model simultaneously improves heat utilization and reduces starting energy consumption, achieving further energy saving and consumption reduction.

[0016] 2. This utility model designs a sleeve seat extending towards the clearance groove on the cylinder head for installing the sleeve and the second spark plug, ensuring that there is enough space to install the decompression mechanism and the second spark plug within the existing cylinder head size, and making the cylinder head and accessories have sufficient strength.

[0017] 3. This utility model further optimizes the layout and installation structure of the dual spark plugs, which can further improve the combustion efficiency of the combustion system and ensure sufficient clearance between the components.

[0018] 4. This utility model uses an installation plane to assemble the intake pipe and muffler, which not only makes installation more convenient and air intake and exhaust smoother, but also allows it to be adapted to various specifications of existing intake pipes and mufflers. Attached Figure Description

[0019] Figure 1 This is a perspective view of the present invention;

[0020] Figure 2 This is a bottom view of the present invention;

[0021] Figure 3 This is a cross-sectional view of the present invention;

[0022] Figure 4 This is a perspective view of the cylinder head of this utility model;

[0023] Figure 5This is a perspective view of the pressure-reducing mechanism of this utility model;

[0024] Reference numerals: 1. Cylinder head; 2. Camshaft; 3. Timing sprocket; 4. Intake assembly; 5. Exhaust assembly; 6. Combustion chamber; 7. Decompression pushrod; 8. First spark plug; 9. Second spark plug; 10. Clearance groove; 11. Sleeve seat; 12. Sleeve; 13. Intake port; 14. Intake mounting plane; 15. Intake pipe; 16. Exhaust port; 17. Exhaust mounting plane; 18. Muffler; 19. One-way centrifugal counterweight; 20. Decompression shaft. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. See also: Figure 1-5 :

[0026] A cylinder head structure for a motorcycle engine includes a cylinder head 1, a camshaft 2 on the top of the cylinder head 1, a timing sprocket 3 mounted on the camshaft 2, an intake assembly 4 and an exhaust assembly 5 on the front and rear sides of the camshaft 2, a combustion chamber 6 below the camshaft 2, a decompression push rod 7 for opening the exhaust valve slidingly disposed within the camshaft 2, a centrifugal mechanism for driving the decompression push rod 7 to slide on the timing sprocket 3, an inclined first spark plug 8 and a second spark plug 9 respectively disposed on the left and right sides of the combustion chamber 6, the angle between the second spark plug 9 and the bottom plane of the cylinder head 1 being smaller than the angle between the first spark plug 8 and the bottom plane of the cylinder head 1, a clearance groove 10 for avoiding the timing sprocket 3 and a sleeve seat 11 extending towards the clearance groove 10, and a sleeve 12 for coaxially mounting the second spark plug 9 disposed within the sleeve seat 11.

[0027] Comparison Appendix Figure 1 In this embodiment, on the one hand, a first spark plug 8 and a second spark plug 9 are respectively arranged on both sides of the hemispherical combustion chamber 6. The distance between these two spark plugs and the center of the combustion chamber 6 is equal. When the engine is idling or running at low speed, a single spark plug is still used for ignition. After normal operation, the two spark plugs ignite simultaneously, which not only shortens the flame propagation distance by half, but also causes the two spark plugs to ignite and explode simultaneously, rapidly forming a strong vortex, which greatly accelerates the flame propagation speed. On the other hand, in the initial stage of engine startup, the pressure relief rod 7 will push open the exhaust valve, creating a gap of about 1 mm, resulting in air leakage. During startup, a low-power pneumatic motor can be used to start the engine to reduce startup energy consumption. After startup, as the speed increases, the centrifugal force increases, and the centrifugal mechanism drives the pressure relief rod 7 to slide, which will not affect the operation of the engine.

[0028] Comparison Appendix Figure 3To improve the combustion efficiency of the combustion system and ensure sufficient clearance between components, this embodiment further optimizes the spark plug layout. The angle α between the first spark plug 8 and the bottom plane of the cylinder head 1 is 52.5°-57.5°; the angle β between the second spark plug 9 and the bottom plane of the cylinder head 1 is 23.5°-26.5°; preferably, the angle α between the first spark plug 8 and the bottom plane of the cylinder head 1 is 55°; and the angle β between the second spark plug 9 and the bottom plane of the cylinder head 1 is 25°.

[0029] Comparison Appendix Figure 4 Furthermore, the sleeve 12 is inclined from the inside to the outside towards the exhaust assembly 5, and the angle γ between the sleeve 12 and the axial vertical plane of the camshaft 2 is 7.5°-8.5°; preferably, the angle γ between the sleeve 12 and the axial vertical plane of the camshaft 2 is 8°.

[0030] In this embodiment, the sleeve seat 11 extends outward from the cylinder wall inside the clearance groove 10 and protrudes from the plane where the cylinder wall is located. The end of the sleeve 12 is inserted into the sleeve seat 11 and sealed. By providing a sleeve seat 11 extending towards the clearance groove 10, the support of the cylinder head 1 on the sleeve 12 can be increased, making the installation structure of the second spark plug 9 more stable. At the same time, sufficient installation space is provided for the timing sprocket 3 and the depressurization mechanism, without affecting the normal operation of the timing sprocket 3 and the depressurization mechanism.

[0031] Comparison Appendix Figure 4 The aforementioned air intake assembly 4 includes an air intake port 13, and an air intake mounting surface 14 is provided at the air intake port 13. The air intake mounting surface 14 is connected to the air intake pipe 15 by fasteners. The exhaust assembly 5 includes an exhaust port 16, and an exhaust mounting surface 17 is provided at the exhaust port 16. The exhaust mounting surface 17 is connected to the muffler 18 by fasteners. The muffler 18 adopts a common type in the art.

[0032] Comparison Appendix Figure 5 In this embodiment, the centrifugal mechanism includes a unidirectional centrifugal counterweight 19 hinged to the timing sprocket 3. The unidirectional centrifugal counterweight 19 is driven by centrifugal force and drives the pressure relief shaft 20 to rotate. The pressure relief shaft 20 drives the pressure relief rod 7 to slide through an eccentric mechanism. Further, the unidirectional centrifugal counterweight 19 is connected to the pressure relief shaft 20 through a pin and a fork. The eccentric mechanism includes: an eccentric drive block at the end of the pressure relief shaft 20, and a drive groove on the pressure relief rod 7 that cooperates with the drive block. Preferably, the pressure relief rod 7 is arranged radially, the drive shaft is arranged axially, and the unidirectional centrifugal counterweight 19 is arranged parallel to the timing sprocket 3.

[0033] The specific working process of the centrifugal decompression mechanism is as follows: At startup, due to the slow speed, the generated centrifugal force is too small. The one-way centrifugal counterweight 19 is driven by the spring and is subjected to an inward rotational force. At this time, the one-way centrifugal counterweight 19 is located in the inner position. Correspondingly, the decompression push rod 7 extends and acts on the exhaust valve to generate a decompression effect. As the speed increases, the centrifugal force on the one-way centrifugal counterweight 19 becomes larger and larger. When it exceeds the force of the spring, it will rotate outward. When the one-way centrifugal counterweight 19 rotates, it drives the decompression shaft 20 to rotate through the pin and the fork. Through the sliding of the eccentric drive block in the drive groove, the decompression push rod 7 gradually retracts inward. When the speed is increased to the set speed, the decompression push rod 7 is completely retracted and does not affect the operation of the engine.

[0034] 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. A cylinder head structure for a motorcycle engine, comprising a cylinder head (1), a camshaft (2) disposed on the top of the cylinder head (1), a timing sprocket (3) mounted on the camshaft (2), an intake assembly (4) and an exhaust assembly (5) disposed on the front and rear sides of the camshaft (2), and a combustion chamber (6) disposed below the camshaft (3), characterized in that, The camshaft (2) is provided with a pressure relief push rod (7) that opens the exhaust valve. The timing sprocket (3) is provided with a centrifugal mechanism that drives the pressure relief push rod (7) to slide. The left and right sides of the combustion chamber (6) are respectively provided with an inclined first spark plug (8) and a second spark plug (9). The angle between the second spark plug (9) and the bottom plane of the cylinder head (1) is smaller than the angle between the first spark plug (8) and the bottom plane of the cylinder head (1). The cylinder head (1) is provided with a clearance groove (10) that avoids the timing sprocket (3) and a sleeve seat (11) that extends towards the clearance groove (10). The sleeve seat (11) is provided with a sleeve (12) for installing the second spark plug (9).

2. The cylinder head structure of a motorcycle engine according to claim 1, characterized in that, The angle between the first spark plug (8) and the bottom plane of the cylinder head (1) is 52.5°-57.5°; the angle between the second spark plug (9) and the bottom plane of the cylinder head (1) is 23.5°-26.5°.

3. The cylinder head structure of a motorcycle engine according to claim 2, characterized in that, The angle between the first spark plug (8) and the bottom plane of the cylinder head (1) is 55°; the angle between the second spark plug (9) and the bottom plane of the cylinder head (1) is 25°.

4. The cylinder head structure of a motorcycle engine according to claim 1, characterized in that, The sleeve (12) is inclined from the inside to the outside towards the exhaust assembly (5), and the angle between the sleeve (12) and the vertical plane of the camshaft (2) is 7.5°-8.5°.

5. The cylinder head structure of a motorcycle engine according to claim 4, characterized in that, The angle between the sleeve (12) and the vertical plane of the camshaft (2) is 8°.

6. The cylinder head structure of a motorcycle engine according to claim 1, characterized in that, The sleeve seat (11) extends outward from the cylinder wall inside the clearance groove (10) and protrudes out of the plane where the cylinder wall is located. The end of the sleeve (12) is inserted into the sleeve seat (11) and sealed.

7. The cylinder head structure of a motorcycle engine according to claim 1, characterized in that, The air intake assembly (4) includes an air intake hole (13), and an air intake mounting surface (14) is provided at the air intake hole (13). The air intake mounting surface (14) is connected to the air intake pipe (15) by fasteners. The exhaust assembly (5) includes an exhaust hole (16), and an exhaust mounting surface (17) is provided at the exhaust hole (16). The exhaust mounting surface (17) is connected to the muffler (18) by fasteners.

8. The cylinder head structure of a motorcycle engine according to claim 1, characterized in that, The centrifugal mechanism includes a unidirectional centrifugal counterweight (19) hinged to the timing sprocket (3). The unidirectional centrifugal counterweight (19) is driven by centrifugal force and drives the pressure relief shaft (20) to rotate. The pressure relief shaft (20) drives the pressure relief rod (7) to slide through an eccentric mechanism.

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