Double-balance-shaft structure of motorcycle engine

Abstract

The invention discloses a motorcycle engine double-balance-shaft structure which comprises a box body, a crankshaft is rotatably connected in the box body, the crankshaft drives a balance shaft I to rotate through a main driving gear and a balance shaft I driven gear, a cylinder head is arranged above the box body, an air inlet cam shaft and an exhaust cam shaft are arranged in the cylinder head, and the air inlet cam shaft and the exhaust cam shaft are arranged in the box body. The crankshaft drives the air inlet cam shaft and the exhaust cam shaft to rotate through the chain and the timing chain wheel, the air inlet cam shaft drives the balance shaft II driven gear to rotate through the balance shaft II driving gear, and the balance shaft II driven gear is arranged on the balance shaft II. The invention belongs to the field of engine balance mechanisms, and particularly relates to a double-balance-shaft structure of a motorcycle engine. Double balance shafts are arranged in limited spaces of all parts of the engine, inertia force and torque generated by movement of the engine are balanced, and therefore vibration of the whole engine is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of engine balancing mechanisms, and in particular relates to a dual-balancing shaft structure for a motorcycle engine. Background Art

[0002] Currently, most motorcycle engines on the market have varying balancer shaft configurations. Many engines lack a balancer shaft, which prevents effective suppression of engine vibration during operation. This vibration can be transmitted to the vehicle body during riding, impacting rider comfort. Prolonged exposure to this vibration can also lead to premature wear of vehicle components and shorten the vehicle's service life. Some engines only have a single balancer shaft. This single balancer shaft utilizes a gear transmission, with crankshaft rotation driving the balancer shaft drive gear and driven gear, which in turn drive the balancer shaft. This design effectively balances the predominantly first-order vibrations and has a certain effect on reducing engine vibration. Due to its simple structure and compact footprint, it is widely used in single-cylinder and small-displacement engines. However, a single balancer shaft cannot effectively address second-order vibrations, limiting its vibration reduction capabilities for users seeking higher comfort and stability, as well as for some high-performance engines. Large-displacement motorcycle engines or those with strict vibration control requirements sometimes utilize a dual balancer shaft configuration. The common dual balance shaft arrangement uses a chain drive to rotate two balance shafts. One balance shaft rotates at the same speed as the engine, eliminating first-order vibrations. The other balance shaft rotates at twice the engine speed, specifically eliminating second-order vibrations, achieving a relatively ideal vibration reduction effect. However, existing dual balance shaft arrangements are typically located within the engine case. This layout has certain drawbacks, such as occupying a significant amount of space within the engine case, restricting the design of the internal engine structure and hindering the optimization of the engine layout and performance within a compact space. Furthermore, the limited operating space within the engine case during installation and maintenance increases repair difficulty and cost. Summary of the Invention

[0003] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a motorcycle engine dual balance shaft structure, which effectively solves the problem of engine vibration.

[0004] The technical solution adopted by the present invention is as follows: The present invention proposes a dual-balance shaft structure of a motorcycle engine, including a housing, a crankshaft rotatably connected inside the housing, the crankshaft drives the balance shaft I to rotate through a main drive gear and a driven gear of the balance shaft I, a cylinder head is provided above the housing, an intake camshaft and an exhaust camshaft are provided inside the cylinder head, the crankshaft drives the intake camshaft and the exhaust camshaft to rotate through a chain and a timing sprocket, the intake camshaft drives the driven gear of the balance shaft II to rotate through the driving gear of the balance shaft II, and the driven gear of the balance shaft II is provided on the balance shaft II.

[0005] Furthermore, a main drive gear is fixedly provided at one end of the crankshaft, the main drive gear is engaged with the driven gear of the balance shaft I, the driven gear of the balance shaft I is fixedly provided at one end of the balance shaft I, and the balance shaft I is assembled in the box.

[0006] Furthermore, a timing sprocket is provided at the same end of the intake camshaft and the exhaust camshaft, and a chain is sleeved on the timing sprocket and the crankshaft, and the chain is engaged with the timing sprocket and the crankshaft.

[0007] Furthermore, a balance shaft II driving gear is provided on the timing sprocket at one end of the intake camshaft, and the timing sprocket and the balance shaft II driving gear are assembled on the intake camshaft through three sets of M6 bolts, and the timing sprocket on the exhaust camshaft is assembled on the exhaust camshaft through two sets of M7 bolts.

[0008] Furthermore, the balancing shaft II driving gear is meshed with the balancing shaft II driven gear, and the balancing shaft II driven gear is locked on the balancing shaft II by a flat key, a washer and a nut.

[0009] Furthermore, the balance shaft II is mounted on the pressure cover I and the pressure cover II through two sets of bearings.

[0010] Furthermore, the intake camshaft and the exhaust camshaft are installed inside the cylinder head through the gland I and the gland II.

[0011] The beneficial effects achieved by the present invention using the above structure are as follows: This solution proposes a dual-balance shaft structure for a motorcycle engine, in which balance shaft I is arranged on the housing to balance the inertial force generated by the up and down movement of the engine piston, and balance shaft II 10 is arranged on the cylinder head 17 to balance the engine torque. This method utilizes the limited space in various parts of the engine to arrange dual balance shafts, balance the inertial force and torque generated by the engine movement, and thus reduce the vibration of the entire machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of a dual-balance shaft structure for a motorcycle engine proposed by the present invention;

[0013] Figure 2 This is a cross-sectional view of a dual-balance shaft structure for a motorcycle engine proposed by the present invention;

[0014] Figure 3 This is a schematic diagram of the locking structure of a motorcycle engine dual balance shaft structure proposed by the present invention.

[0015] Among them, 1. Main drive gear; 2. Crankshaft; 3. Case; 4. Chain; 5. Balance shaft I; 6. Balance shaft I driven gear; 7. Timing sprocket; 8. Balance shaft II driving gear; 9. M6 bolt; 10. Balance shaft II; 11. Balance shaft II driven gear; 12. Pressure cover I; 13. Pressure cover II; 14. M7 bolt; 15. Gasket; 16. Nut; 17. Cylinder head; 18. Flat key; 19. Bearing; 20. Intake camshaft; 21. Exhaust camshaft.

[0016] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0018] In the description of the present invention, it should be understood that terms such as "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0019] like Figure 1-Figure 3 As shown, the present invention proposes a dual-balance shaft structure for a motorcycle engine, including a housing 3, in which a crankshaft 2 is rotatably connected. The crankshaft 2 drives the balance shaft I 5 to rotate through a main drive gear 1 and a balance shaft I driven gear 6. A cylinder head 17 is provided above the housing 3, and an intake camshaft 20 and an exhaust camshaft 21 are provided inside the cylinder head 17. The crankshaft 2 drives the intake camshaft 20 and the exhaust camshaft 21 to rotate through a chain 4 and a timing sprocket 7. The intake camshaft 20 drives the balance shaft II driven gear 11 to rotate through a balance shaft II driving gear 8. The balance shaft II driven gear 11 is provided on the balance shaft II 10.

[0020] During operation, the crankshaft 2 within the housing 3 rotates the main drive gear 1, which, through the meshing of the main drive gear 1 with the driven gear 6 of balance shaft I, drives the rotation of balance shaft I 5. Simultaneously, the crankshaft 2 drives the intake camshaft 20 and exhaust camshaft 21 within the cylinder head 17 via the chain 4 and timing sprocket 7. The intake camshaft 20 then drives balance shaft II 10 through the meshing of balance shaft II driving gear 8 and the driven gear 11 of balance shaft II. Dual balance shafts are positioned within the housing 3 and cylinder head 17, respectively, forming a coordinated balancing system within the limited space. Balance shaft I 5 specifically balances the inertial forces generated by the upward and downward motion of the engine pistons, while balance shaft II 10 counteracts the torque generated during engine operation. Together, these two balance shafts significantly reduce overall vibration, resolving the problem of a single balance shaft's inability to achieve comprehensive vibration reduction.

[0021] Among them, a main drive gear 1 is fixedly provided at one end of the crankshaft 2, and the main drive gear 1 is engaged with the driven gear 6 of the balance shaft I. The driven gear 6 of the balance shaft I is fixedly provided at one end of the balance shaft I5, and the balance shaft I5 is assembled in the box body 3.

[0022] During operation, the main drive gear 1 at one end of the crankshaft 2 rotates synchronously with the crankshaft. Through meshing with the driven gear 6 of the balance shaft 1, it transmits power to the balance shaft 15, causing it to rotate at a specific speed. The balance shaft 15 is assembled within the housing 3, utilizing the housing's space for stable support. The rotation direction of the balance shaft 15 is opposite to that of the crankshaft 2. The inertial force generated by its eccentric mass offsets the first-order inertial force of the reciprocating piston motion, reducing longitudinal engine vibration and improving operating smoothness.

[0023] Among them, the same end of the intake camshaft 20 and the exhaust camshaft 21 are both provided with a timing sprocket 7, and the timing sprocket 7 and the crankshaft 2 are sleeved with a chain 4, which is engaged with the timing sprocket 7 and the crankshaft 2.

[0024] In operation, the timing sprockets 7 at the same ends of the intake and exhaust camshafts 20 and 21 are connected to the crankshaft 2 via a chain 4, forming a synchronous transmission mechanism. As the crankshaft 2 rotates, the chain 4 drives the timing sprockets 7, causing the camshafts to rotate according to the valve timing phase, while also providing power to the balancer shaft II 10. This chain drive ensures a precise phase relationship between the camshafts and the crankshaft 2, ensuring proper operation of the valve timing system and providing stable power to the balancer shaft II 10, synchronizing its vibration cancellation with the engine's operating rhythm.

[0025] Among them, a balance shaft II driving gear 8 is provided on the timing sprocket 7 at one end of the intake camshaft 20. The timing sprocket 7 and the balance shaft II driving gear 8 are assembled on the intake camshaft 20 through three sets of M6 bolts 9, and the timing sprocket 7 on the exhaust camshaft 21 is assembled on the exhaust camshaft 21 through two sets of M7 bolts 14.

[0026] In operation, the timing sprocket 7 on the intake camshaft 20 and the balance shaft II driving gear 8 are fastened together using three sets of M6 bolts 9 to ensure synchronous rotation. The timing sprocket 7 on the exhaust camshaft 21 is secured with two sets of M7 bolts 14 to ensure transmission stability. The bolted connection withstands radial forces from the sprocket drive, preventing loosening. Different bolt sizes are used to adapt to the load requirements of different camshafts. The M6 ​​bolts 9 meet the drive load of the intake camshaft 20, while the M7 bolts 14 are adapted to the working load of the exhaust camshaft 21, ensuring a secure connection between the transmission components and preventing phase shift caused by vibration.

[0027] Among them, the balancing shaft II driving gear 8 is engaged with the balancing shaft II driven gear 11, and the balancing shaft II driven gear 11 is locked on the balancing shaft II 10 through a flat key 18, a gasket 15 and a nut 16.

[0028] During operation, the balance shaft II driving gear 8 meshes with the balance shaft II driven gear 11, transmitting power from the intake camshaft 20 to the balance shaft II 10. The balance shaft II driven gear 11 is circumferentially secured by a flat key 18, and axially locked with a washer 15 and nut 16 to prevent relative slippage between the two gears. The balance shaft II driven gear 11 rotates the balance shaft II 10, and the counter-torque generated by its eccentric design offsets the engine's tilting torque caused by the camshaft's rotation, reducing lateral vibration in the cylinder head 17.

[0029] The balancing shaft II 10 is mounted on the pressure cover I 12 and the pressure cover II 13 through two sets of bearings 19 .

[0030] During operation, balance shaft II 10 is mounted on glands I 12 and II 13 via two sets of bearings 19. The bearings 19 reduce frictional resistance during balance shaft II 10's rotation, while the glands provide axial positioning and radial support for the bearings, ensuring smooth operation of balance shaft II 10. The dual bearings 19 support and disperse radial forces on balance shaft II 10, preventing bending deformation caused by the cantilever structure. The coordination between the glands and cylinder head 17 further enhances the installation precision of balance shaft II 10, ensuring effective vibration cancellation.

[0031] The intake camshaft 20 and the exhaust camshaft 21 are installed inside the cylinder head 17 through the pressure cover I 12 and the pressure cover II 13 .

[0032] During operation, the intake and exhaust camshafts 20 and 21 are secured within the cylinder head 17 via glands I 12 and II 13. These glands both limit axial movement of the camshafts and provide radial support. Together with bearings 19, they ensure stability during high-speed rotation. The stable operation of the camshafts provides reliable power input to balancer shaft II 10. The rigid connection of the glands allows the vibration-damping effect of balancer shaft II 10 to directly affect the cylinder head 17, significantly reducing the transmission of engine vibration to the vehicle body through balancer shaft I 5 within the housing 3.

[0033] The actual operation process is very simple and easy. The crankshaft in the housing 3 drives the main drive gear 1 to rotate, and the engagement of the main drive gear 1 with the driven gear 6 of the balance shaft I drives the balance shaft I5 to rotate. The balance shaft I5 specifically balances the inertia force generated by the up and down movement of the engine piston; at the same time, the crankshaft 2 drives the intake camshaft 20 and the exhaust camshaft 21 in the cylinder head through the chain 4 and the timing sprocket 7 to operate according to the valve timing phase. The balance shaft II driving gear 8 at one end of the intake camshaft 20 engages with the driven gear 11 of the balance shaft II, thereby driving the balance shaft II10 to work. The balance shaft II10 is responsible for offsetting the torque when the engine is running. The dual balance shafts use the limited space of the housing and the cylinder head to synergistically reduce the vibration of the entire machine.

[0034] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0035] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0036] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A motorcycle engine dual balance shaft structure, characterized by: The invention comprises a housing (3), wherein a crankshaft (2) is rotatably connected in the housing (3), and the crankshaft (2) drives the balance shaft I (5) to rotate through a main drive gear (1) and a balance shaft I driven gear (6). A cylinder head (17) is arranged above the housing (3), and an intake camshaft (20) and an exhaust camshaft (21) are arranged inside the cylinder head (17). The crankshaft (2) drives the intake camshaft (20) and the exhaust camshaft (21) to rotate through a chain (4) and a timing sprocket (7). The intake camshaft (20) drives the balance shaft II driven gear (11) to rotate through a balance shaft II driving gear (8), and the balance shaft II driven gear (11) is arranged on the balance shaft II (10).

2. The dual balance shaft structure of a motorcycle engine according to claim 1, characterized in that: A main drive gear (1) is fixedly provided at one end of the crankshaft (2), the main drive gear (1) is meshed with a driven gear (6) of a balancing shaft I, the driven gear (6) of the balancing shaft I is fixedly provided at one end of a balancing shaft I (5), and the balancing shaft I (5) is assembled in a housing (3).

3. The motorcycle engine dual balance shaft structure according to claim 2, characterized in that: The same end of the intake camshaft (20) and the exhaust camshaft (21) are both provided with a timing sprocket (7), and a chain (4) is sleeved on the timing sprocket (7) and the crankshaft (2), and the chain (4) is meshed with the timing sprocket (7) and the crankshaft (2).

4. The dual balance shaft structure of a motorcycle engine according to claim 3, characterized in that: A balance shaft II driving gear (8) is provided on the timing sprocket (7) at one end of the intake camshaft (20); the timing sprocket (7) and the balance shaft II driving gear (8) are assembled on the intake camshaft (20) through three groups of M6 bolts (9); and the timing sprocket (7) on the exhaust camshaft (21) is assembled on the exhaust camshaft (21) through two groups of M7 bolts (14).

5. The dual balance shaft structure of a motorcycle engine according to claim 4, characterized in that: The balancing shaft II driving gear (8) is meshed with the balancing shaft II driven gear (11), and the balancing shaft II driven gear (11) is locked on the balancing shaft II (10) through a flat key (18), a washer (15) and a nut (16).

6. The dual balance shaft structure of a motorcycle engine according to claim 5, characterized in that: The balancing shaft II (10) is mounted on the pressure cover I (12) and the pressure cover II (13) via two sets of bearings (19).

7. The motorcycle engine dual balance shaft structure according to claim 6, characterized in that: The intake camshaft (20) and the exhaust camshaft (21) are installed inside the cylinder head (17) through a pressure cover I (12) and a pressure cover II (13).

Images