Crankshaft balance structure and engine

By incorporating an integrated primary gear, weight reduction section, and counterweight section on the crankshaft of a multi-cylinder motorcycle engine, the size and vibration issues of the crankshaft structure are resolved, achieving compactness, lightweight design, and uniform stress distribution, thereby reducing bearing wear and vibration.

CN223662338UActive Publication Date: 2025-12-12LONCIN MOTOR CO LTD +1
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Patent Information

Application Number
CN202520560811.0
Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
Filing Date
2025-03-27
Publication Date
2025-12-12
Estimated Expiration
2035-03-27

AI Technical Summary

Technical Problem

Existing multi-cylinder engine crankshafts for motorcycles suffer from problems such as long lateral dimensions, easy wear of bearings, and high vibration, making it impossible to simultaneously meet the requirements of reducing axial and radial dimensions and minimizing vibration.

Method used

The primary gear and crankshaft body are integrated into one structure, with weight reduction and counterweight components to reduce unbalanced torque and distribute the force evenly on the bearings. The integrated design reduces the crankshaft's lateral dimension and rotation space, thereby reducing vibration.

Benefits of technology

It achieves a compact and lightweight crankshaft structure, reduces abnormal wear of bearings, lowers first-order vibration, and is suitable for the use of medium and large displacement multi-cylinder engines.

✦ Generated by Eureka AI based on patent content.

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Abstract

The utility model discloses a crankshaft balance structure and an engine, and relates to the technical field of internal combustion engines, the crankshaft balance structure comprises a crankshaft body, and the crankshaft body comprises a main journal, a connecting rod journal, a balance block and a primary gear. And the main journal and the bearing bush are assembled on a crankshaft box body. The connecting rod journal is used for being connected with a connecting rod so as to transmit reciprocating motion of a piston in an engine cylinder to the crankshaft body. The balance block is arranged on the crankshaft body and used for counteracting inertia force and vibration generated when the engine operates. The primary gear and the crankshaft body are integrally arranged, the primary gear is provided with a weight reduction part and a balance weight part, the weight reduction part is used for reducing the overall weight, and the balance weight part is used for counteracting vibration and inertia force generated during operation of an engine. According to the crankshaft balance structure, the transverse size of the crankshaft body is reduced, the structure is more compact, the bearing bush supporting distance is uniform, abnormal abrasion can be reduced, the strength is high, the slipping fault of a press-fitting gear is avoided, and the crankshaft balance structure is more suitable for the requirement of a medium-large displacement multi-cylinder engine.
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Description

TECHNICAL FIELD

[0001] The utility model relates to internal combustion engine technical field, especially a crankshaft balance structure and engine. BACKGROUND

[0002] The existing motorcycle multi-cylinder engine generally adopts two kinds of primary gear arrangement ways, the first kind is independent primary gear structure, adopts the crankshaft structure of completely symmetrical balance block, and adds pressure assembly or assembly primary gear to realize transmission, and this kind of arrangement dynamic balance effect is good, but it has the following shortcomings:

[0003] Long transverse dimension: this kind of crankshaft structure needs to leave primary gear position to carry out power transmission, causes the longer transverse dimension of crankshaft. The primary gear of pressure assembly is generally built-in inside timing chain inside, and then will cause the synchronous widening of cylinder head and cylinder body;

[0004] Bearing easy to wear: the multi-cylinder engine crankshaft adopts bearing support form, and the primary gear is arranged in the bearing support inside of the fourth cylinder two sides of crankshaft, causes the fourth cylinder bearing support spacing to increase relative to other cylinders, and the torque received increases, and is more easy to wear.

[0005] The second kind of common four-cylinder crankshaft structure is to process one of the two balance blocks of one cylinder (generally the fourth cylinder) into primary transmission gear, and the other single balance block is balanced, and this structure is smaller in axial dimension, but has the following shortcomings:

[0006] Balance block outer diameter is large: since the primary transmission gear occupies the balance block position, the outer diameter of the other balance block must be increased to ensure the balance amount of the crankshaft, which further increases the rotation space of the entire crankshaft and the volume of the engine;

[0007] Crankshaft vibration is large: due to uneven arrangement of balance blocks, the torque received by the bearings on both sides of the primary gear (fourth cylinder) is uneven, and the first-order vibration of the engine is large. Since the first cylinder and the fourth cylinder of the four-cylinder engine crankshaft must be arranged symmetrically, the bearings on both sides of the first cylinder are also unevenly stressed, further increasing the vibration.

[0008] Therefore, there are still defects and deficiencies in the prior art, and how to provide a crankshaft balance structure and engine that satisfies the reduction of axial and radial dimensions while minimizing vibration is a technical problem that needs to be solved by those skilled in the art. UTILITY MODEL CONTENTS

[0009] The utility model aims at providing a crankshaft balance structure and engine, solving the technical problem that the crankshaft structure of the existing motorcycle multi-cylinder engine has many defects and cannot meet the use requirements.

[0010] To achieve the above-mentioned purpose, the utility model provides a crankshaft balance structure, comprising a crankshaft body, the crankshaft body comprising:

[0011] Main journal, used for fitting with bearing shells in the crankcase;

[0012] Connecting rod journal, used to connect with the connecting rod to transmit the reciprocating motion of the piston in the engine block to the crankshaft body;

[0013] A counterweight, located on the crankshaft body, is used to counteract the inertial forces and vibrations generated during engine operation;

[0014] The primary gear is integrally formed with the crankshaft body and has a weight reduction part and a counterweight part. The weight reduction part is used to reduce the overall weight, and the counterweight part is used to counteract the vibration and inertial force generated when the engine is running.

[0015] Preferably, the weight-reducing part is a weight-reducing groove provided on the primary gear, and the weight-reducing groove is arc-shaped, U-shaped or V-shaped.

[0016] Preferably, the counterweight is a counterweight block or counterweight plate disposed on the primary gear.

[0017] Preferably, a timing primary gear is integrally provided at one end of the crankshaft body where a primary gear is located.

[0018] Preferably, the main journal includes a first main journal, a second main journal, a third main journal, a fourth main journal, and a fifth main journal distributed sequentially along the crankshaft body.

[0019] Preferably, the connecting rod journal includes a first connecting rod journal, a second connecting rod journal, a third connecting rod journal, and a fourth connecting rod journal distributed sequentially along the crankshaft body.

[0020] Preferably, the main journal and the connecting rod journal are arranged alternately.

[0021] Preferably, the primary gear is located between the fourth connecting rod journal and the fifth main shaft journal.

[0022] Preferably, the balance block is located between the third main spindle journal and the third connecting rod journal.

[0023] This utility model also provides an engine, including the crankshaft balancing structure provided by any of the above technical solutions.

[0024] Compared to the aforementioned background technology, the crankshaft balancing structure provided by this utility model adopts an integrated structure of the primary gear and the crankshaft body. This not only reduces the lateral dimension of the crankshaft body, making the structure more compact, but also ensures uniform bearing support spacing, reducing abnormal wear. Furthermore, it boasts high strength and eliminates the risk of slippage in press-fitted gears, making it more suitable for medium-to-large displacement multi-cylinder engines. Simultaneously, the primary gear is equipped with weight-reducing and counterweight components, minimizing the unbalanced torque on each journal of the crankshaft body and ensuring uniform stress on the bearings at each journal, thus reducing vibration and abnormal wear. By incorporating weight-reducing components, the outer diameter of the balance weights does not need to be excessively large to achieve a balancing effect. The overall crankshaft rotation space is small, thereby reducing engine size and ultimately achieving the goals of lower crankshaft body vibration, a compact structure, and lightweight design.

[0025] The engine can produce the same technical effects as the crankshaft balancing structure. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a cross-sectional view of the crankshaft balancing structure provided in an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the primary gear in the crankshaft balancing structure provided in this embodiment of the utility model;

[0029] Figure 3 A schematic diagram of the engine provided in an embodiment of this utility model;

[0030] Figure 4 This is a cross-sectional structural diagram of the engine provided in an embodiment of the present invention.

[0031] Figures 1 to 4 Chinese reference numerals: 10, crankshaft body; 21, first main shaft journal; 22, second main shaft journal; 23, third main shaft journal; 24, fourth main shaft journal; 25, fifth main shaft journal; 31, first connecting rod journal; 32, second connecting rod journal; 33, third connecting rod journal; 34, fourth connecting rod journal; 40, balance weight; 50, primary gear; 51, weight reduction section; 52, counterweight section; 60, timing primary gear; 100, crankshaft balancing structure; 200, engine. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0033] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] This utility model provides a crankshaft balancing structure 100, which reduces vibration while reducing axial and radial dimensions. By using the weight reduction part 51 and the counterweight part 52 provided on the primary gear 50, the torque is balanced, reducing the unbalanced torque on the bearings on both sides and reducing the first-order vibration.

[0035] Please refer to this as well. Figures 1 to 2 The crankshaft balancing structure 100 provided by this utility model includes a crankshaft body 10, which includes a main journal, a connecting rod journal, a balance block 40, and a primary gear 50.

[0036] The main journal is used to mate with the bearing shell in the crankcase. The main journal is a cylindrical journal that supports the crankshaft body 10 and is the core support point when the crankshaft body 10 rotates. The main journal disperses the inertial force and combustion pressure when the crankshaft body 10 rotates by providing multi-point support, thereby reducing local loads and wear.

[0037] The connecting rod journal connects to the connecting rod to transmit the reciprocating motion of the piston in the engine block 200 to the crankshaft body 10. The connecting rod journal is a journal on the crankshaft body 10 that connects to the big end of the connecting rod. It converts the reciprocating linear motion of the piston into the rotational motion of the crankshaft body 10, and is a core component of the engine 200's power output. The connecting rod journal, in conjunction with the balance weight 40, counteracts the centrifugal force generated by the piston's movement, reducing vibration and bearing wear in the crankshaft body 10.

[0038] The balance weight 40 is located on the crankshaft body 10 and is used to counteract the inertial force and vibration generated when the engine 200 is running. The balance weight 40 is a metal counterweight component in the engine 200 used to adjust the distribution of rotating mass and can counteract the inertial force and vibration generated when the engine 200 is running.

[0039] The primary gear 50 is integrally formed with the crankshaft body 10. The primary gear 50 is provided with a weight reduction part 51 and a counterweight part 52. The weight reduction part 51 is used to reduce the overall weight, and the counterweight part 52 is used to counteract the vibration and inertial force generated when the engine 200 is running.

[0040] The primary gear 50 and the crankshaft body 10 adopt an integrated structure, that is, the balance block on the outside of the fourth cylinder is machined into the primary gear 50, reducing the lateral dimension of the crankshaft body 10, making the structure more compact, with sufficient timing chain cavity space, allowing for a narrower lateral width of the cylinder block and cylinder head, uniform bearing support spacing, reducing abnormal wear, and high strength, preventing slippage of press-fitted gears, making it more suitable for medium and large displacement multi-cylinder engines. At the same time, a weight-reducing part 51 and a counterweight part 52 are set on the primary gear 50 to minimize the unbalanced torque on each journal of the crankshaft body 10, ensuring uniform stress on the bearings at each journal, reducing vibration and abnormal wear. By setting the weight-reducing part 51, the outer diameter of the balance block 40 does not need to be too large to achieve the balancing effect, the entire crankshaft rotation space is small, the engine volume 200 is reduced, and thus the crankshaft body 10 achieves the goals of less vibration, compact structure, and lightweight design.

[0041] Please refer to this as well. Figures 1 to 2 The weight reduction part 51 is a weight reduction groove provided on the primary gear 50. The weight reduction groove is located on the outside of the primary gear 50. In this embodiment, the weight reduction groove is arc-shaped, U-shaped or V-shaped, etc. In other embodiments, other forms may be used, and no specific limitation is made.

[0042] Please refer to this as well. Figures 1 to 2 The counterweight 52 is a counterweight block or counterweight plate located on the primary gear 50. With partial counterweight on the primary gear 50, compared to a single counterweight block, the outer diameter does not need to be too large to achieve vibration balancing, thus reducing the size of the engine 200.

[0043] Please refer to this as well. Figures 1 to 2 The crankshaft body 10 has a primary timing gear 60 integrally mounted on one end of the primary gear 50. The primary timing gear 60 is integrally mounted on the front end of the crankshaft body 10 and meshes with the camshaft timing gear through a chain, belt, or gear set to form a rigid transmission chain, ensuring that the crankshaft body 10 synchronously drives the camshaft when rotating. The primary timing gear 60 is used to avoid valve-piston collision through precise meshing, while optimizing combustion efficiency.

[0044] Please refer to this as well. Figures 1 to 2 The main journals include a first main journal 21, a second main journal 22, a third main journal 23, a fourth main journal 24 and a fifth main journal 25, which are distributed sequentially along the crankshaft body 10.

[0045] Please refer to this as well. Figures 1 to 2 The connecting rod journals include a first connecting rod journal 31, a second connecting rod journal 32, a third connecting rod journal 33, and a fourth connecting rod journal 34, which are distributed sequentially along the crankshaft body 10.

[0046] Please refer to this as well. Figures 1 to 2The main journals and connecting rod journals are arranged alternately, that is, a connecting rod journal is set between every two main journals. Specifically, the first main journal 21, the first connecting rod journal 31, the second main journal 22, the second connecting rod journal 32, the third main journal 23, the third connecting rod journal 33, the fourth main journal 24, the fourth connecting rod journal 34, and the fifth main journal 25 are arranged in sequence.

[0047] The alternating distribution of main journals and connecting rod journals helps optimize the stress on the crankshaft body 10, reduce local stress concentration, and extend service life.

[0048] Please refer to this as well. Figures 1 to 2 The primary gear 50 is located between the fourth connecting rod journal 34 and the fifth main shaft journal 25.

[0049] Please refer to this as well. Figures 1 to 2 The balance block 40 is located between the third main spindle journal 23 and the third connecting rod journal 33.

[0050] The crankshaft balancing structure 100 provided by this utility model features an integrated structure of the primary gear 50 and the crankshaft body 10. This structure not only boasts high strength and eliminates slippage issues associated with press-fitted gears, making it more suitable for medium-to-large displacement multi-cylinder engines, but also reduces the lateral dimension of the crankshaft body 10, resulting in a more compact structure, sufficient timing chain cavity space, narrower lateral width of the cylinder block and cylinder head, and uniform bearing support spacing, thus reducing abnormal wear. Simultaneously, the primary gear 50 is equipped with a weight-reducing part 51 and a counterweight part 52, minimizing the unbalanced torque on each journal of the crankshaft body 10 and ensuring uniform bearing stress at each journal, thereby reducing vibration and abnormal wear. By incorporating the weight-reducing part 51, the outer diameter of the balance block 40 does not need to be excessively large to achieve a balancing effect, resulting in a smaller overall crankshaft rotation space and a smaller engine volume 200. This further contributes to a crankshaft body 10 with less vibration, a more compact structure, and lighter weight.

[0051] Please refer to this as well. Figures 1 to 2 Figures 1 to 2 Figures 3 to 4 In addition to the crankshaft balancing structure 100 disclosed in the above embodiments, the present invention also provides an engine 200 including the above-mentioned crankshaft balancing structure 100.

[0052] The engine 200 includes a crankshaft balancing structure 100, and thus can produce the same technical effects as the crankshaft balancing structure 100.

[0053] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0054] This article uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of this utility model.

Claims

1. A crankshaft balancing structure (100), characterized by, The crankshaft body (10) comprises: a main journal for fitting with a bearing in a crankcase; a connecting rod journal for connecting with a connecting rod to transmit the reciprocating motion of a piston in a cylinder of an engine (200) to the crankshaft body (10); a balance weight (40) provided on the crankshaft body (10) for counteracting inertial force and vibration generated during operation of the engine (200); a primary gear (50) provided integrally with the crankshaft body (10) and provided with a weight-reducing portion (51) for reducing the overall weight and a counterweight portion (52) for counteracting vibration and inertial force generated during operation of the engine (200).

2. The crankshaft counterbalance structure (100) according to claim 1, characterized in that, The weight-reducing portion (51) is a weight-reducing groove provided on the primary gear (50) and has a circular arc shape, a U shape or a V shape.

3. The crankshaft balancing structure (100) according to claim 2, characterized in that The counterweight portion (52) is a counterweight block or a counterweight plate provided on the primary gear (50).

4. The crankshaft counterbalance structure (100) according to claim 3, characterized in that One end of the crankshaft body (10) provided with the primary gear (50) is integrally provided with a timing primary gear (60).

5. The crankshaft balancing structure (100) according to claim 4, characterized in that The main journal comprises a first main journal (21), a second main journal (22), a third main journal (23), a fourth main journal (24) and a fifth main journal (25) arranged in sequence along the crankshaft body (10).

6. The crankshaft balancing structure (100) according to claim 5, characterized in that The connecting rod journal comprises a first connecting rod journal (31), a second connecting rod journal (32), a third connecting rod journal (33) and a fourth connecting rod journal (34) arranged in sequence along the crankshaft body (10).

7. The crankshaft balancing structure (100) according to claim 6, characterized in that The main journal and the connecting rod journal are arranged alternately.

8. The crankshaft balancing structure (100) according to claim 7, characterized in that The primary gear (50) is located between the fourth connecting rod journal (34) and the fifth main journal (25).

9. The crankshaft balancing structure (100) according to claim 8, characterized in that The balance weight (40) is located between the third main journal (23) and the third connecting rod journal (33).

10. An engine (200) characterized by, The crankshaft balancing structure (100) according to any one of claims 1 to 9.