Balance shaft of motorcycle engine
By designing the clearance fit and lubrication structure of the motorcycle engine balance shaft, the problem of easy damage to the balance shaft bearing was solved, achieving a long bearing life and stable engine operation.
Patent Information
- Application Number
- CN202520263552.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-19
- Publication Date
- 2026-02-17
- Estimated Expiration
- 2035-02-19
AI Technical Summary
The balance shaft bearing of a motorcycle engine is prone to damage and has a short service life under prolonged lateral thrust.
Design a motorcycle engine balance shaft, in which both ends are inserted into the inner ring of the balance bearing through clearance fit, and lubrication is achieved by oil collection grooves and oil holes. The balance shaft is driven to rotate synchronously through gear transmission, and the counterweight generates lateral thrust to balance the inertial force.
It effectively disperses the stress points on the inner ring of the balance shaft bearing, extends the service life of the balance shaft bearing, reduces wear, and improves the operating stability of the motorcycle engine.
Smart Images
Figure CN223923703U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of motorcycle technology, and in particular to a motorcycle engine balance shaft. Background Technology
[0002] During the operation of a motorcycle engine, the piston reciprocates at high speed within the cylinder at high speed and unevenly. The piston, piston pin, and connecting rod generate a large inertial force. To balance this inertial force, a counterweight is added to the crankshaft. However, adding a counterweight to the crankshaft can only balance the longitudinal inertial force and is difficult to balance the lateral inertial force. To balance the lateral inertial force, many engines have added a balance shaft to reduce vibration and improve the riding experience.
[0003] During operation, the balance shaft rotates synchronously in the opposite direction at high speed with the crankshaft. Due to the counterweight on the balance shaft, a lateral thrust is generated. Since the balance shaft and the inner ring of the balance shaft bearing are rigidly connected, the lateral thrust can only act on a certain point on the inner ring of the balance shaft bearing, while other positions on the inner ring are not affected by the lateral thrust. Under long-term stress, a certain point on the inner ring of the balance shaft bearing is easily damaged, resulting in a reduction in the service life of the balance shaft bearing. Utility Model Content
[0004] The purpose of this invention is to provide a motorcycle engine balance shaft that overcomes the above-mentioned defects and improves the service life of the balance shaft bearing.
[0005] To achieve the above objectives, the solution of this utility model is as follows:
[0006] A motorcycle engine balance shaft is provided. The balance shaft is installed inside the crankcase, which also houses the crankshaft and balance shaft bearings. The crankshaft and balance shaft are connected by gear transmission, enabling the crankshaft to drive the balance shaft to rotate synchronously. The two balance shaft bearings are spaced apart inside the crankcase. The two ends of the balance shaft are respectively inserted into the inner rings of the two balance shaft bearings with a clearance fit. When the balance shaft rotates, relative rotation can occur between the two ends of the balance shaft and the inner rings of the balance shaft bearings, so that the lateral thrust of the balance shaft acts on different points of the inner rings of the balance shaft bearings.
[0007] Furthermore, the balance shaft is equipped with an oil collection groove containing machine oil, and an oil hole is provided at the mating point between the balance shaft bearing and the balance shaft. Through the oil hole, the machine oil in the oil collection groove can flow to the mating point between the balance shaft bearing and the balance shaft, thereby providing lubrication.
[0008] Furthermore, the sidewall of the balance shaft protrudes to one side to form a counterweight, which is used to generate lateral thrust when the balance shaft rotates.
[0009] Furthermore, the side wall in the middle of the balance shaft is recessed to form a recessed portion, and the side wall of the balance shaft opposite the recessed portion is raised to form the counterweight block, which is used to generate lateral thrust when the balance shaft rotates.
[0010] Furthermore, an oil collection groove is provided inside the balance shaft on both sides of the recess. One end of the oil collection groove is connected to the recess, and the other end extends axially to the end of the balance shaft to form an opening. A plug is detachably installed in this opening to seal the oil collection groove.
[0011] Furthermore, oil holes are provided inside the balance shaft on both sides of the recess. One end of the oil hole is connected to the oil collection groove, and the other end extends radially to the side wall of the balance shaft to form an opening. This opening is located within the coverage area of the balance shaft bearing. The oil in the oil collection groove can flow into the balance shaft and the balance shaft bearing through the oil hole to form an oil film and lubricate the balance shaft bearing.
[0012] Furthermore, each end of the balance shaft has a first insert for inserting into the inner ring of the corresponding balance shaft bearing. The diameter of the first insert is smaller than the diameter of the balance shaft and also smaller than the diameter of the inner ring of the balance shaft bearing. When the first insert is inserted into the inner ring of the balance shaft bearing, the balance shaft bearing abuts against the balance shaft.
[0013] Furthermore, a second insert is formed on one of the first inserts. The diameter of the second insert is smaller than that of the first insert. A drive gear is provided on the crankshaft, and a driven gear is provided on the balance shaft. The drive gear drives the driven gear to rotate. The driven gear is sleeved on the second insert. A keyway is provided on the driven gear. A semi-circular key is provided on the second insert to engage with the keyway. The semi-circular key engages with the keyway to drive the balance shaft to rotate when the driven gear rotates. The length of the first insert is greater than the thickness of the balance shaft bearing. When the driven gear is sleeved on the second insert, it abuts against the first insert and is separated from the balance shaft bearing.
[0014] Furthermore, the balance shaft bearing is a rolling bearing, which consists of an inner ring, an outer ring, a cage, and rolling elements between the inner and outer rings.
[0015] After adopting the above solution, the beneficial effects of this utility model are as follows:
[0016] The two ends of the balance shaft of this invention are respectively inserted into the inner rings of two balance shaft bearings with a clearance fit. When the balance shaft rotates, the two ends of the balance shaft and the inner rings of the balance shaft bearings can generate relative rotation, so that the lateral thrust of the balance shaft acts on different points of the inner rings of the balance shaft bearings, thereby preventing damage to the balance shaft bearings and improving the service life of the balance shaft bearings. Attached Figure Description
[0017] Figure 1 This is an assembly diagram of the balance shaft of this utility model.
[0018] Figure 2 This is a schematic diagram of the specific structure of the balance shaft of this utility model;
[0019] Figure 3 This is a diagram showing the fit between the balance shaft and the balance shaft bearing of this utility model;
[0020] Figure 4 This is a cross-sectional view of the balance shaft of this utility model;
[0021] Figure 5 This is a schematic diagram of the passive gear of this utility model being engaged with the second insert rod.
[0022] Label Explanation:
[0023] 10. Balance shaft; 11. Driven gear; 12. Counterweight; 13. Recess; 14. Oil collection groove; 141. Plug; 15. Oil hole; 16. First insert rod; 17. Second insert rod; 171. Semicircular key; 20. Crankcase; 30. Crankshaft; 31. Drive gear; 40. Balance shaft bearing. Detailed Implementation
[0024] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0025] like Figures 1 to 5 As shown, this utility model provides a motorcycle engine balance shaft 10. The balance shaft 10 is installed inside a crankcase 20, which also houses a crankshaft 30 and balance shaft bearings 40. The crankshaft 30 and balance shaft 10 are connected by gear transmission, so that the crankshaft 30 drives the balance shaft 10 to rotate synchronously. The two balance shaft bearings 40 are spaced apart inside the crankcase 20. The two ends of the balance shaft 10 are respectively inserted into the inner rings of the two balance shaft bearings 40 with a clearance fit. When the balance shaft 10 rotates, the two ends of the balance shaft 10 and the inner rings of the balance shaft bearings 40 can rotate relative to each other, so that the lateral thrust of the balance shaft 10 acts on different points of the inner rings of the balance shaft bearings 40.
[0026] Furthermore, an oil collection groove 14 is provided inside the balance shaft 10, which contains machine oil. An oil hole 15 is provided at the mating point between the balance shaft bearing 40 and the balance shaft 10. The machine oil in the oil collection groove 14 can flow to the mating point between the balance shaft bearing 40 and the balance shaft 10 under the action of centrifugal force through the oil hole 15, thereby lubricating and reducing the wear of the balance shaft 10 and the balance shaft bearing 40.
[0027] Furthermore, the sidewall of the balance shaft 10 protrudes to one side to form a counterweight 12, which is used to generate lateral thrust when the balance shaft 10 rotates.
[0028] Specifically, the side wall of the balance shaft 10 is recessed to form a recess 13, and the side wall of the balance shaft 10 opposite to the recess 13 is raised to form the counterweight 12, which is used to generate lateral thrust when the balance shaft 10 rotates. It can be understood that the balance shaft 10 at the recess 13 is eccentrically set relative to the balance shafts 10 on both sides of the recess 13. Therefore, the counterweight 12 is formed on the side wall of the balance shaft 10 opposite to the recess 13, and the lateral thrust generated when the balance shaft 10 rotates is greater.
[0029] Furthermore, an oil collection groove 14 is provided in the balance shaft 10 on both sides of the recess 13. One end of the oil collection groove 14 is connected to the recess 13, and the other end extends axially to the end of the balance shaft 10 to form an opening. A plug 141 is detachably provided in this opening to block the oil collection groove 14. When the engine is running, the engine oil splashes and can be collected and stored in the oil collection groove 14.
[0030] Furthermore, oil holes 15 are provided in the balance shafts 10 on both sides of the recess 13. One end of the oil hole 15 is connected to the oil collection groove 14, and the other end extends radially to the side wall of the balance shaft 10 to form an opening. This opening is located within the coverage area of the balance shaft bearing 40. The oil in the oil collection groove 14 can flow into the space between the balance shaft 10 and the balance shaft bearing 40 through the oil hole 15 to form an oil film and lubricate the balance shaft bearing 40. This makes it easier for the balance shaft 10 and the balance shaft bearing 40 to rotate relative to each other, reduces the wear of the balance shaft 10 and the balance shaft bearing 40, and makes it easier to change the position of the lateral thrust acting on the inner ring of the balance shaft bearing 40, further improving the service life of the balance shaft bearing 40.
[0031] Specifically, the balance shaft 10 has a first insert 16 at each end for inserting into the inner ring of the corresponding balance shaft bearing 40. The diameter of the first insert 16 is smaller than the diameter of the balance shaft 10 and also smaller than the diameter of the inner ring of the balance shaft bearing 40. When the first insert 16 is inserted into the inner ring of the balance shaft bearing 40, the balance shaft bearing 40 abuts against the balance shaft 10. It can be understood that the oil hole 15 mentioned above is specifically set on the first insert 16.
[0032] Specifically, a second insert 17 is formed on one of the first inserts 16. The diameter of the second insert 17 is smaller than that of the first insert 16. A drive gear 31 is provided on the crankshaft 30, and a driven gear 11 is provided on the balance shaft 10. The drive gear 31 drives the driven gear 11 to rotate. The driven gear 11 is sleeved on the second insert 17. A keyway is provided on the driven gear 11, and a semi-circular key 171 is provided on the second insert 17 to engage with the keyway. The keyway and the semi-circular key 171 engage to drive the driven gear 11 to rotate. When the dynamic balance shaft 10 rotates, the length of the first insert rod 16 is greater than the thickness of the balance shaft bearing 40. When the driven gear 11 is sleeved on the second insert rod 17, it abuts against the first insert rod 16 and is separated from the balance shaft bearing 40. It can be understood that the length of the first insert rod 16 with the second insert rod 17 is greater than the thickness of the balance shaft bearing 40 sleeved on it. Therefore, when the driven gear 11 is locked on the second insert rod 17, it at most abuts against the end of the first insert rod 16 away from the balance shaft 10, rather than against the balance shaft bearing 40.
[0033] Specifically, the balance shaft bearing 40 is a rolling bearing, which consists of an inner ring, an outer ring, a cage, and rolling elements between the inner and outer rings. It can be understood that the inner ring of the balance shaft mentioned above is the same as the inner ring of the rolling bearing.
[0034] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention, primarily used to illustrate the embodiments and to explain the operating principles of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.
[0035] Furthermore, the directions such as front, back, left, and right mentioned in this embodiment are only for reference and do not represent the actual directions in use. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0036] The above description is only a preferred embodiment of this utility model and is not a limitation on the design of this case. All equivalent changes made based on the key design of this case shall fall within the protection scope of this case.
Claims
1. A motorcycle engine balance shaft, wherein the balance shaft is disposed within a crankcase, the crankcase also contains a crankshaft and balance shaft bearings, the crankshaft and balance shaft are connected by gear transmission to enable the crankshaft to drive the balance shaft to rotate synchronously, and two balance shaft bearings are spaced apart within the crankcase, characterized in that: The two ends of the balance shaft are respectively inserted into the inner rings of the two balance shaft bearings with clearance fit. When the balance shaft rotates, the two ends of the balance shaft and the inner rings of the balance shaft bearings can generate relative rotation, so that the lateral thrust of the balance shaft acts on different points of the inner rings of the balance shaft bearings.
2. A motorcycle engine balance shaft as claimed in claim 1, characterized in that: The balance shaft has an oil collection groove containing machine oil. There is an oil hole at the mating point between the balance shaft bearing and the balance shaft. The machine oil in the oil collection groove can flow to the mating point between the balance shaft bearing and the balance shaft through the oil hole, thereby providing lubrication.
3. A motorcycle engine balance shaft as claimed in claim 1, characterized in that: The sidewall of the balance shaft protrudes to one side to form a counterweight, which is used to generate lateral thrust when the balance shaft rotates.
4. A motorcycle engine balance shaft as described in claim 3, characterized in that: The side wall in the middle of the balance shaft is recessed to form a recessed portion, and the side wall of the balance shaft opposite the recessed portion is raised to form the counterweight block, which is used to generate lateral thrust when the balance shaft rotates.
5. A motorcycle engine balance shaft as described in claim 4, characterized in that: Oil collection grooves are provided inside the balance shafts on both sides of the recess. One end of the oil collection groove is connected to the recess, and the other end extends axially to the end of the balance shaft to form an opening. A plug is detachably installed in this opening to seal the oil collection groove.
6. A motorcycle engine balance shaft as described in claim 5, characterized in that: Oil holes are provided inside the balance shaft on both sides of the recess. One end of the oil hole is connected to the oil collection groove, and the other end extends radially to the side wall of the balance shaft to form an opening. This opening is located within the coverage area of the balance shaft bearing. The oil in the oil collection groove can flow into the balance shaft and the balance shaft bearing through the oil hole to form an oil film and lubricate the balance shaft bearing.
7. A motorcycle engine balance shaft as described in claim 1, characterized in that: The balance shaft has a first insert at each end for inserting into the inner ring of the corresponding balance shaft bearing. The diameter of the first insert is smaller than the diameter of the balance shaft and also smaller than the diameter of the inner ring of the balance shaft bearing. When the first insert is inserted into the inner ring of the balance shaft bearing, the balance shaft bearing abuts against the balance shaft.
8. A motorcycle engine balance shaft as described in claim 7, characterized in that: A second insert is formed on one of the first inserts. The diameter of the second insert is smaller than that of the first insert. A drive gear is provided on the crankshaft, and a driven gear is provided on the balance shaft. The drive gear drives the driven gear to rotate. The driven gear is sleeved on the second insert. A keyway is provided on the driven gear. A semi-circular key is provided on the second insert to engage with the keyway. The semi-circular key engages with the keyway to drive the balance shaft to rotate when the driven gear rotates. The length of the first insert is greater than the thickness of the balance shaft bearing. When the driven gear is sleeved on the second insert, it abuts against the first insert and is separated from the balance shaft bearing.
9. A motorcycle engine balance shaft as described in claim 1, characterized in that: The balance shaft bearing is a rolling bearing, which consists of an inner ring, an outer ring, a cage, and rolling elements between the inner and outer rings.