A motorcycle engine crankcase
By introducing a protective layer combined with a T-shaped slider groove design and a three-dimensional reinforcement structure of reinforcing ribs and support blocks into the crankcase of a motorcycle engine, the problems of crankcase wear and stress concentration are solved, and durability and rigidity are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GUANGDONG RUIZHEN TECH CO LTD
- Filing Date
- 2025-09-10
- Publication Date
- 2026-06-26
AI Technical Summary
Existing motorcycle engine crankcases are prone to wear during high-speed rotation, especially under harsh working conditions where the wear rate accelerates. This can lead to crankshaft eccentricity and oil leakage. Furthermore, a single reinforcing rib cannot distribute multi-directional loads, resulting in localized stress concentration and making cracks more likely.
The design combines a protective layer with a T-shaped slider groove, along with a three-dimensional reinforced layout of ring ribs, support blocks, transverse columns, and side wall ribs. The protective layer reduces wear through contact with the crankshaft, while the slider allows for slight sliding to accommodate thermal expansion and contraction. The reinforcing ribs and support blocks distribute the load, ensuring a balance between rigidity and lightweight design.
It effectively prevents wear on the inner wall of the crankcase, extends service life, reduces stress cracking caused by temperature changes, improves durability and adaptability, enhances overall rigidity, and avoids local stress concentration.
Smart Images
Figure CN224413763U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of motorcycle engine technology, specifically a motorcycle engine crankcase. Background Technology
[0002] The crankcase of a motorcycle engine is the core load-bearing component of the engine. Its main function is to house and support key power components such as the crankshaft and transmission gear set. As the skeleton of the overall engine structure, it must withstand the complex loads generated by the reciprocating motion of the piston, the high-speed rotation of the crankshaft, and the meshing of the gears. Its structural stability, wear resistance, and rigidity directly affect the engine's power output efficiency, operational reliability, and service life, making it one of the core aspects of motorcycle engine design.
[0003] The existing motorcycle engine crankcases have the following main shortcomings:
[0004] In existing motorcycle engines, the crankcase is the core of the engine's power output. During high-speed rotation, the long-term friction and vibration between the crankcase and the inner wall or bearing housing can easily lead to wear on the inner wall of the crankcase. Especially under harsh working conditions, the wear rate is accelerated, which may cause crankshaft eccentricity, oil leakage, or even structural failure. Furthermore, a single reinforcing rib cannot disperse multi-directional loads, resulting in local stress concentration. The single reinforcement dimension cannot fully disperse loads in different directions, leading to obvious stress concentration in local areas, which can easily cause cracks after long-term use. Utility Model Content
[0005] To overcome the above-mentioned defects, this utility model provides a crankcase for a motorcycle engine, which solves the problem that in the prior art, the crankcase, as the core of engine power output, is prone to wear of the inner wall of the crankcase due to long-term friction and vibration with the inner wall or bearing housing during high-speed rotation. Especially under harsh working conditions, the wear rate is accelerated, which may cause crankshaft eccentricity, oil leakage, or even structural failure.
[0006] To achieve the above objectives, the present invention provides the following technical solution: a crankcase for a motorcycle engine, comprising a crankcase body, a crankshaft receiving cavity provided on one side of the center of the upper end face of the crankcase body, a gear mounting cavity provided on the other side of the center of the upper end face of the crankcase body, a protective structure provided on the inner sidewall of the crankshaft receiving cavity, and a reinforcing structure provided at the center of the lower end face of the crankcase body;
[0007] The protective structure includes a protective layer, which is sleeved on the inner wall of the crankcase body. The outer wall of the protective layer is provided with multiple sliders arranged in a ring, and the inner wall of the crankshaft receiving cavity is provided with multiple grooves arranged in a ring. The multiple sliders are slidably connected to the multiple grooves, and the multiple sliders and multiple grooves are all T-shaped.
[0008] As a further embodiment of this utility model: the reinforcing structure includes a first reinforcing rib, which is disposed at the center of the lower end face of the crankshaft receiving cavity, and three support blocks are arranged in a ring at the center of the lower end face of the crankshaft receiving cavity.
[0009] As a further embodiment of this utility model: a second reinforcing rib is provided on one rear side of the upper end face of the crankcase body, and both the first reinforcing rib and the second reinforcing rib are circular.
[0010] As a further embodiment of this utility model: multiple support columns are arranged laterally at the center of the front inner wall and the rear inner wall of the crankshaft receiving cavity, and multiple third reinforcing ribs are arranged front and back at the center of the inner side wall of the crankshaft receiving cavity.
[0011] As a further aspect of this utility model, the connecting edges of the crankcase body, the crankshaft housing cavity, and the gear mounting cavity are all designed with rounded corners.
[0012] As a further embodiment of this utility model: the upper end face of the crankcase body is provided with multiple positioning pin holes.
[0013] As a further embodiment of this utility model: a crankshaft main bearing is provided at the front center of the crankshaft housing cavity.
[0014] As a further embodiment of this utility model: a main bearing for the gear transmission shaft is provided at the center of the gear transmission mounting cavity, and an auxiliary bearing for the gear transmission shaft is provided on one side of the gear transmission mounting cavity near the front.
[0015] As a further embodiment of this utility model: two connecting bearing rods are arranged laterally on one side of the center of the front end face of the crankcase body, and the outer side walls of the two connecting bearing rods are threaded.
[0016] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0017] This invention, through the combined design of a protective layer, a T-shaped slider, and a groove, prevents the protective layer from shifting and falling off due to high-frequency crankshaft vibration by radial limiting, while retaining a small amount of axial sliding space to accommodate thermal expansion and contraction during engine operation. This solves the problem of stress cracking caused by temperature changes in rigid protective structures. At the same time, the direct contact between the protective layer and crankshaft components achieves wear isolation. Combined with the sliding assembly structure, this significantly improves the durability and adaptability of the protection.
[0018] This invention utilizes a three-dimensional reinforced layout of annular ribs, support blocks, transverse columns, and side wall ribs to achieve precise reinforcement targeting the stress characteristics of different areas of the crankcase. The combination of the first reinforcing rib and the support block directionally resists the radial force and cavity bottom pressure of the crankshaft rotation. The second reinforcing rib focuses on the connection rigidity of the transmission gear cavity. The support column and the third reinforcing rib respectively enhance the deformation resistance of the cavity in the front-back direction and the side wall, ensuring overall rigidity while avoiding excessive weight gain, thus achieving a balance between strength and lightweight. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the three-dimensional structure of the present invention. Figure 1 ;
[0020] Figure 2 This is a schematic diagram of the three-dimensional structure of the present invention. Figure 2 ;
[0021] Figure 3 This is a top view of the structure of this utility model;
[0022] Figure 4 This is a three-dimensional, disassembled structural diagram of the protective structure of this utility model.
[0023] In the diagram: 1. Crankcase body; 2. Crankshaft housing cavity; 3. Gearbox mounting cavity; 4. Connecting bearing rod; 5. Protective structure; 501. Protective layer; 502. Slider; 503. Slide groove; 6. Reinforcing structure; 601. First reinforcing rib; 602. Support block; 603. Second reinforcing rib; 604. Support column; 605. Third reinforcing rib; 7. Crankshaft main bearing; 8. Gearbox auxiliary bearing; 9. Gearbox main bearing. Detailed Implementation
[0024] The technical solution of this patent will be further described in detail below with reference to specific embodiments.
[0025] like Figures 1-4 As shown, this utility model provides a technical solution:
[0026] A motorcycle engine crankcase, comprising:
[0027] The crankcase body 1 has a crankshaft housing cavity 2 located on one side of the center of the upper end face of the crankcase body 1, and a gear mounting cavity 3 located on the other side of the center of the upper end face of the crankcase body 1. The inner wall of the crankshaft housing cavity 2 has a protective structure 5, and the center of the lower end face of the crankcase body 1 has a reinforcing structure 6. The connecting edges of the crankcase body 1, the crankshaft housing cavity 2, and the gear mounting cavity 3 are all designed with rounded corners. The upper end face of the crankcase body 1 has multiple positioning pin holes. The crankshaft main bearing 7 is located at the front center of the crankshaft housing cavity 2. The gear mounting cavity 3 has a gear shaft main bearing 9 located at the center of the gear shaft. The gear shaft auxiliary bearing 8 is located at the front side of one side of the gear mounting cavity 3. Two connecting bearing rods 4 are arranged laterally on one side of the center of the front end face of the crankcase body 1. The front side of the outer wall of the two connecting bearing rods 4 is threaded.
[0028] The crankcase body 1 serves as the core load-bearing structure. The crankshaft housing 2 and the transmission gear mounting cavity 3 correspond to the two key power components of the engine: the crankshaft and the transmission gear set. The crankshaft is mounted in the crankshaft housing 2 via the crankshaft main bearing 7. The rotational characteristics of the crankshaft main bearing 7 enable the high-speed rotation of the crankshaft, converting the reciprocating motion of the piston into rotational power. The transmission gear set is mounted in the transmission gear mounting cavity 3 via the transmission shaft main bearing 9 and the transmission shaft auxiliary bearing 8. The meshing and switching of multiple gear sets achieve the power speed and torque. The adjustment of the crankcase body 1 and the crankshaft housing 2 is fixedly connected to other engine components through the outer thread, ensuring the rigid assembly of the crankcase body 1 and the overall structure. The rounded corner transition design of the connecting edges of the crankcase body 1, crankshaft housing 2 and transmission gear mounting cavity 3 can disperse the stress concentration at the connection parts of different cavities and avoid cracks caused by long-term vibration at sharp corners. Multiple positioning pin holes on the upper end face ensure the precise alignment of the crankcase and cylinder block and other components during assembly, ensuring the coaxiality of the power transmission path and reducing additional wear or vibration caused by assembly deviation.
[0029] The protective structure 5 includes a protective layer 501, which is fitted onto the inner wall of the crankcase body 1. Multiple sliders 502 are arranged in a ring on the outer wall of the protective layer 501. Multiple grooves 503 are arranged in a ring on the inner wall of the crankshaft housing cavity 2. The sliders 502 are slidably connected to the grooves 503. All sliders 502 and grooves 503 are T-shaped. The protective structure 5 on the inner wall of the crankshaft housing cavity 2 achieves double protection through the cooperation of the protective layer 501, sliders 502, and grooves 503. The protective layer 501 is in direct contact with the outside of the crankshaft or crankshaft bearing. It uses an alloy coating or high-strength plastic to reduce direct friction loss during crankshaft rotation. At the same time, the protective layer 501 is embedded in the T-shaped groove 503 of the crankshaft receiving cavity 2 through the T-shaped slider 502. This not only limits the radial displacement of the protective layer 501 itself to avoid displacement or detachment caused by crankshaft vibration, but also allows a small amount of axial sliding to adapt to thermal expansion and contraction, ensuring that the protective effect is continuously effective and extending the service life of the inner wall of the crankcase body 1.
[0030] The reinforcing structure 6 includes a first reinforcing rib 601, which is located at the center of the lower end face of the crankshaft housing 2. Three support blocks 602 are arranged in a ring at the center of the lower end face of the crankshaft housing 2. A second reinforcing rib 603 is located on one rear side of the upper end face of the crankshaft housing 1. Both the first and second reinforcing ribs 601 and 603 are annular. Multiple support columns 604 are arranged laterally at the center of the front and rear inner walls of the crankshaft housing 2. Multiple third reinforcing ribs 605 are arranged front-to-back at the center of one inner wall of the crankshaft housing 2. The first reinforcing rib 601 surrounds the outer periphery of the crankshaft main bearing 7, reinforcing the structure of the crankshaft main bearing 7 mounting area. The strength is enhanced to resist the radial force generated by the crankshaft rotation. Three ring-shaped support blocks 602 further disperse the pressure transmitted from the crankshaft to the bottom of the cavity, preventing local stress concentration. The second reinforcing rib 603 strengthens the rigidity of the connection between the transmission gear mounting cavity 3 and the main body, and, together with the support of the transmission shaft main bearing 9, reduces the vibration of the housing during gear meshing. Multiple support columns 604 on the front and rear inner walls of the crankshaft housing 2 are laterally distributed to enhance the cavity's resistance to deformation in the front and rear directions and to offset the axial impact force generated by the crankshaft rotation. The third reinforcing rib 605 on the inner side wall is arranged front and rear to further strengthen the structural strength of the cavity side wall and prevent the side wall from bulging or cracking due to the eccentric rotation of the crankshaft.
[0031] The working principle of this utility model is as follows: the crankcase body 1 serves as the core load-bearing structure. The crankshaft housing cavity 2 and the transmission gear mounting cavity 3 correspond to the two key power components of the engine: the crankshaft and the transmission gear set. The crankshaft is mounted in the crankshaft housing cavity 2 via the crankshaft main bearing 7. The high-speed rotation of the crankshaft is achieved by utilizing the rotational characteristics of the crankshaft main bearing 7, converting the reciprocating motion of the piston into rotational power. The transmission gear set is mounted in the transmission gear mounting cavity 3 via the transmission shaft main bearing 9 and the transmission shaft auxiliary bearing 8. The power is achieved by utilizing the meshing and switching of multiple sets of gears. The adjustment of speed and torque, the connecting bearing rod 4 is fixedly connected to other engine components through the outer thread to ensure the rigid assembly of the crankcase body 1 with the whole machine structure. The rounded transition design of the connecting edge of the crankcase body 1, crankshaft housing cavity 2 and transmission gear mounting cavity 3 can disperse the stress concentration at the connection parts of different cavities and avoid cracks caused by long-term vibration at sharp corners. Multiple positioning pin holes on the upper end face ensure the precise alignment of the crankcase and cylinder block and other components during assembly, ensure the coaxiality of the power transmission path, and reduce additional wear or vibration caused by assembly deviation.
[0032] The protective structure 5 on the inner wall of the crankshaft housing 2 achieves double protection through the cooperation of a protective layer 501, a slider 502, and a groove 503. The protective layer 501 directly contacts the outer side of the crankshaft or crankshaft bearing, and uses an alloy coating or high-strength plastic to reduce direct frictional loss during crankshaft rotation. Simultaneously, the protective layer 501 is embedded in the T-shaped groove 503 of the crankshaft housing 2 via the T-shaped slider 502. This restricts the radial displacement of the protective layer 501 itself, preventing displacement or detachment due to crankshaft vibration, while allowing a small amount of axial sliding to accommodate thermal expansion and contraction, ensuring continuous and effective protection and extending the service life of the inner wall of the crankcase body 1. The first reinforcing rib 601 surrounds the outer periphery of the crankshaft main bearing 7, increasing... The structural strength of the crankshaft main bearing 7 mounting location is enhanced to resist the radial force generated by crankshaft rotation. Three ring-shaped support blocks 602 further disperse the pressure transmitted from the crankshaft to the bottom of the cavity, preventing local stress concentration. The second reinforcing rib 603 strengthens the rigidity of the connection between the transmission gear mounting cavity 3 and the main body, and, in conjunction with the support of the transmission shaft main bearing 9, reduces the vibration of the housing during gear meshing. Multiple support columns 604 on the front and rear inner walls of the crankshaft housing 2 are laterally distributed to enhance the cavity's resistance to deformation in the front and rear directions and to offset the axial impact force generated by crankshaft rotation. The third reinforcing rib 605 on the inner sidewall is arranged front and rear to further strengthen the structural strength of the cavity sidewall and prevent sidewall bulging or cracking caused by eccentric crankshaft rotation.
[0033] Furthermore, the control method of this utility model is controlled by a controller. The control circuit of the controller can be implemented by simple programming by those skilled in the art. The power supply is also common knowledge in the art. Since this utility model is used to protect mechanical devices, the control method and circuit connection will not be explained in detail.
[0034] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A crankcase for a motorcycle engine, characterized in that: The crankcase includes a crankcase body (1), a crankshaft receiving cavity (2) is provided on one side of the center of the upper end face of the crankcase body (1), a gear mounting cavity (3) is provided on the other side of the center of the upper end face of the crankcase body (1), a protective structure (5) is provided on the inner wall of the crankshaft receiving cavity (2), and a reinforcing structure (6) is provided at the center of the lower end face of the crankcase body (1). The protective structure (5) includes a protective layer (501), which is sleeved on the inner wall of the crankcase body (1). The outer wall of the protective layer (501) is provided with a plurality of sliders (502) arranged in a ring. The inner wall of the crankshaft receiving cavity (2) is provided with a plurality of sliding grooves (503) arranged in a ring. The plurality of sliders (502) are slidably connected to the interior of the plurality of sliding grooves (503). The plurality of sliders (502) and the plurality of sliding grooves (503) are all T-shaped.
2. The crankcase of a motorcycle engine according to claim 1, characterized in that: The reinforcing structure (6) includes a first reinforcing rib (601), which is located at the center of the lower end face of the crankshaft receiving cavity (2). The center of the lower end face of the crankshaft receiving cavity (2) is provided with three support blocks (602) arranged in a ring.
3. A motorcycle engine crankcase according to claim 2, characterized in that: The crankcase body (1) has a second reinforcing rib (603) located at the rear of one side of the upper end face. Both the first reinforcing rib (601) and the second reinforcing rib (603) are annular.
4. A motorcycle engine crankcase according to claim 1, characterized in that: Multiple support columns (604) are arranged laterally at the center of the front inner wall and the rear inner wall of the crankshaft housing (2), and multiple third reinforcing ribs (605) are arranged front and back at the center of one inner side wall of the crankshaft housing (2).
5. A motorcycle engine crankcase according to claim 1, characterized in that: The connecting edges of the crankcase body (1), crankshaft housing cavity (2) and gear mounting cavity (3) are all designed with rounded corners.
6. A motorcycle engine crankcase according to claim 1, characterized in that: The upper surface of the crankcase body (1) is provided with multiple positioning pin holes.
7. A motorcycle engine crankcase according to claim 1, characterized in that: The crankshaft housing cavity (2) is provided with a crankshaft main bearing (7) at the front of the center.
8. A motorcycle engine crankcase according to claim 1, characterized in that: The gear mounting cavity (3) is provided with a gear shaft main bearing (9) at the center, and a gear shaft auxiliary bearing (8) is provided on one side of the gear mounting cavity (3) near the front.
9. A motorcycle engine crankcase according to claim 1, characterized in that: Two connecting bearing rods (4) are arranged laterally on one side of the center of the front end face of the crankcase body (1), and the outer side walls of the two connecting bearing rods (4) are threaded.