Crankcase, engine and motorcycle

Abstract

This application relates to a crankcase, an engine, and a motorcycle. The crankcase includes: a housing, a suspension protrusion, a first rib, a second rib, a third rib, and a fourth rib. The housing contains a crankshaft cavity and a counterspindle hole. The suspension protrusion has a suspension hole along a first direction. The housing also contains a clearance groove. The first and second ribs are located on either side of the line connecting the centers of the suspension hole and the counterspindle hole. The third and fourth ribs are both located within the crankshaft cavity, with the third rib surrounding the outer periphery of the clearance groove. One end of the fourth rib extends in the first direction away from the bottom wall of the crankshaft cavity, and the other end of the fourth rib at least partially surrounds the counterspindle hole. This crankcase improves the structural strength at the suspension hole, reduces the risk of cracking at the suspension hole, and thus enhances the safety of motorcycle operation.

Description

Technical Field

[0001] This application relates to the field of motorcycle technology, and in particular to a crankcase, an engine, and a motorcycle. Background Technology

[0002] In motorcycles, suspension holes are located on the engine for connection to the frame. These holes must withstand the vibrations generated by the engine itself, as well as the forces transmitted from the frame during vehicle movement. In related technologies, the structural strength of these suspension holes is relatively low, potentially leading to cracking during vehicle operation and consequently, poor motorcycle safety. Summary of the Invention

[0003] Therefore, it is necessary to provide a crankcase, engine, and motorcycle that improves the structural strength of the suspension holes and reduces the risk of structural cracking at the suspension holes, thereby enhancing the safety of motorcycle operation.

[0004] In a first aspect, embodiments of this application provide a crankcase, comprising:

[0005] The housing has a crankshaft cavity and a counterspindle hole inside, with the counterspindle hole located on the bottom wall of the crankshaft cavity;

[0006] A suspension protrusion is connected to the outer peripheral wall of the housing, and the suspension protrusion has a suspension hole along a first direction;

[0007] The housing is also provided with a clearance groove, which is located between the secondary shaft hole and the suspension hole;

[0008] The first rib and the second rib are both located outside the crankshaft cavity. The first rib and the second rib are arranged on both sides of the line connecting the center of the suspension hole and the auxiliary shaft hole. The first rib and the second rib are both used to connect the suspension protrusion and the outer peripheral wall of the housing.

[0009] The third and fourth ribs are both located within the crankshaft cavity. The third rib is disposed on the bottom wall of the crankshaft cavity, surrounds the outer periphery of the clearance groove, and is connected to the inner peripheral wall of the crankshaft housing. One end of the fourth rib extends in the first direction away from the bottom wall of the crankshaft cavity and is connected to the side of the third rib near the inner peripheral wall of the crankshaft cavity. The other end of the fourth rib, facing away from the crankshaft cavity, at least partially surrounds the auxiliary shaft hole and is connected to the side of the third rib away from the inner peripheral wall of the crankshaft cavity.

[0010] In one embodiment, the first rib includes a first sub-rib and a second sub-rib. There are multiple first sub-ribs, which are spaced apart in the first direction. The first sub-ribs are used to connect the suspension protrusion to the outer peripheral wall of the box. The second sub-ribs extend along the first direction and are used to connect two adjacent first sub-ribs.

[0011] In one embodiment, a recess is formed between the side of the second rib facing away from the first rib and the outer peripheral wall of the suspension protrusion. The crankcase also includes a fifth rib and a sixth rib, which are respectively disposed on opposite sides of the recess. One end of the fifth rib and the sixth rib are connected to the second rib, and the other ends of the fifth rib and the sixth rib facing away from each other are connected to the outer peripheral wall of the suspension protrusion.

[0012] In one embodiment, the second rib protrudes from the outer peripheral wall of the housing.

[0013] In one embodiment, the minimum distance between the first rib and the second rib is less than the outer diameter of the suspension protrusion.

[0014] In one embodiment, the third rib includes a first connecting segment and a second connecting segment connected together, both of which are arranged around the clearance groove. The end of the first connecting segment away from the second connecting segment is connected to the inner peripheral wall of the crankshaft cavity, and the end of the second connecting segment away from the first connecting segment is connected to the fourth rib.

[0015] In one embodiment, the fourth rib includes a third connecting segment and a fourth connecting segment connected together;

[0016] One end of the third connecting segment extends along the bottom wall away from the crankshaft cavity in the first direction and is connected to the inner peripheral wall of the crankshaft cavity; the other end of the third connecting segment opposite to the crankshaft cavity is connected to the bottom wall of the crankshaft cavity and its end is connected to one end of the fourth connecting segment.

[0017] The fourth connecting section is located on the bottom wall of the crankshaft cavity, the fourth connecting section is arranged around the auxiliary shaft hole, and the end of the fourth connecting section away from the third connecting section is connected to the third rib.

[0018] In one embodiment, the distance from both ends of the third connecting segment to the bottom wall of the crankshaft cavity is greater than the distance from the middle of the third connecting segment to the bottom wall of the crankshaft cavity.

[0019] Secondly, embodiments of this application also provide an engine, including a crankcase cover and a crankcase as described in any one of the first aspects, wherein one end of the crankcase body away from the bottom wall of the crankshaft cavity is provided with a cover profile surface for connecting with the crankcase cover.

[0020] Thirdly, embodiments of this application also provide a motorcycle, including a frame and the engine described in the second aspect, wherein the frame and the engine are connected via the suspension hole.

[0021] The aforementioned crankcase includes a first and a second rib located outside the crankshaft cavity. Both ribs connect the suspension protrusion to the outer peripheral wall of the crankcase, increasing the structural strength of the connection between the outer side of the crankcase and the suspension protrusion. A third and a fourth rib are also provided inside the crankshaft cavity. The third rib is located on the bottom wall of the crankshaft cavity and surrounds the outer periphery of the clearance groove. One end of the fourth rib extends in a first direction away from the bottom wall of the crankshaft cavity and connects to the side of the third rib near the inner peripheral wall of the crankshaft cavity. The other end of the fourth rib at least partially surrounds the auxiliary shaft hole and connects to the side of the third rib away from the inner peripheral wall of the crankshaft cavity. The third and fourth ribs increase the structural strength of the inner side of the crankcase near the suspension protrusion, simultaneously enhancing the structural strength at the connection points between the inner and outer sides of the crankcase and the suspension protrusion. This improves the structural strength at the suspension hole, reduces the risk of cracking at the suspension hole, and enhances the safety of the motorcycle. Attached Figure Description

[0022] Figure 1 This is a partial structural diagram of the crankcase in one embodiment of this application.

[0023] Figure 2 for Figure 1 Top view of the crankcase.

[0024] Figure 3 This is a schematic diagram of the structure of the first rib in one embodiment of this application.

[0025] Figure 4 This is a schematic diagram of the structure of the second rib in one embodiment of this application.

[0026] Figure 5 This is a partial enlarged view of the second rib in one embodiment of this application.

[0027] Figure 6 for Figure 5 A cross-sectional view along the AA direction.

[0028] The attached figures are labeled as follows:

[0029] 1. Housing; 110. Crankshaft cavity; 120. Sub-shaft hole; 130. Clearance groove; 140. Cover contour surface; 2. Suspension protrusion; 21. Suspension hole; 3. First rib; 31. First sub-rib; 32. Second sub-rib; 4. Second rib; 41. Recess; 5. Third rib; 51. First connecting section; 52. Second connecting section; 6. Fourth rib; 61. Third connecting section; 62. Fourth connecting section; 7. Fifth rib; 8. Sixth rib. Detailed Implementation

[0030] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0031] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0032] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0033] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0035] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0036] See Figure 1 An embodiment of this application provides a crankcase including a housing 1, a suspension protrusion 2, a first rib 3, a second rib 4, a third rib 5, and a fourth rib 6. The housing 1 contains a crankshaft cavity 110, a countershaft hole 120, and a clearance groove 130. Specifically, the crankshaft cavity 110 houses the engine's transmission structure (such as a countershaft and crankshaft), the countershaft passes through the countershaft hole 120, and the clearance groove 130 is located between the countershaft hole 120 and the suspension hole 21 to prevent interference between the transmission structure and the housing 1 during installation. The suspension protrusion 2 is connected to the outer peripheral wall of the housing 1, and the suspension protrusion 2 has a suspension hole 21 along a first direction for connecting the crankcase to the vehicle frame.

[0037] like Figure 1 and Figure 2As shown, to enhance the structural strength of the connection between the suspension protrusion 2 and the outer peripheral wall of the housing 1, the first rib 3 and the second rib 4 are both located outside the crankshaft cavity 110. The first rib 3 and the second rib 4 are positioned on both sides of the line connecting the axes of the suspension hole 21 and the auxiliary shaft hole 120. Both the first rib 3 and the second rib 4 connect the suspension protrusion 2 and the outer peripheral wall of the housing 1, thereby increasing the contact area between the suspension protrusion 2 and the outer peripheral wall of the housing 1, and thus increasing the structural strength of the connection between the outer side of the housing 1 and the suspension protrusion 2. It should be noted that the first rib 3 and the second rib 4 are positioned on both sides of the line connecting the axes of the suspension hole 21 and the auxiliary shaft hole 120, creating two independent and cooperative force transmission paths between the suspension protrusion 2 and the outer peripheral wall of the housing 1. This prevents localized stress concentration and cracking of the suspension protrusion 2, and improves the stability of the connection between the suspension protrusion 2 and the housing 1.

[0038] Furthermore, such as Figure 1 and Figure 3 As shown, in order to simplify the structure of the first rib 3 while giving it better structural strength, in some embodiments, the first rib 3 includes a first branch rib 31 and a second branch rib 32. There are multiple first branch ribs 31, which are spaced apart in a first direction. The first branch ribs 31 are used to connect the suspension protrusion 2 to the outer peripheral wall of the box body 1. The second branch ribs 32 extend along the first direction and are used to connect two adjacent first branch ribs 31.

[0039] It should be noted that the first reinforcing bar 31, as the main load-bearing component, is arranged equidistantly along the first direction. This avoids excessive load concentration in local areas and ensures that the first reinforcing bar 31 can achieve uniform load distribution when bearing the external force transmitted by the suspension protrusion 2, thereby effectively improving the fatigue resistance and load-bearing capacity of the overall structure. Figure 3 As shown, one end of the first rib 31 is directly connected to the suspension protrusion 2, and the other end of the first rib 31 is connected to the outer peripheral wall of the box 1, so that the suspension load can be stably transmitted to the structure of the box 1, avoiding stress abrupt changes caused by a single connection point. In addition, the second rib 32 extends along the first direction and is used to connect two adjacent first ribs 31, so that the first rib 3 is subjected to uniform stress throughout. In one embodiment, as... Figure 3 As shown, there are two first reinforcing bars 31 and one second reinforcing bar 32, with the second reinforcing bar 32 located between the two first reinforcing bars 31. The number of first reinforcing bars 31 and second reinforcing bars 32 can be adjusted adaptively according to the load required to be borne at the suspension hole 21.

[0040] In this application, the housing 1, the suspension protrusion 2, the first rib 3, the second rib 4, the third rib 5, and the fourth rib 6 are integrally formed using a casting process, such as... Figure 4 and Figure 5As shown, to avoid excessive wall thickness (dimension in the first direction) of the second rib 4, which could lead to casting defects due to solidification shrinkage at the connection between the second rib 4 and the housing 1 and the suspension protrusion 2 during the casting process, thus affecting the casting quality of the second rib 4, a recess 41 is formed between the side of the second rib 4 facing away from the first rib 3 and the outer peripheral wall of the suspension protrusion 2. This reduces the thickness of the second rib 4 in a localized area, thereby improving the casting quality. Furthermore, to compensate for the reduced connection strength between the second rib 4 and the suspension protrusion 2 caused by the localized thinning of the second rib 4, and to enhance the load transfer capacity and bending / torsional resistance between the second rib 4 and the suspension protrusion 2, in one embodiment, the crankcase also includes a fifth rib 7 and a sixth rib 8. The fifth rib 7 and the sixth rib 8 are respectively located on opposite sides of the recess 41. One end of each of the fifth rib 7 and the sixth rib 8 is connected to the second rib 4, and the other ends of each of the fifth rib 7 and the sixth rib 8 facing away from each other are connected to the outer peripheral wall of the suspension protrusion 2. The fifth rib 7 and the sixth rib 8 effectively share the bending stress and shear stress of the second rib 4 under cantilever stress, and improve the connection strength between the second rib 4 and the suspension protrusion 2.

[0041] Furthermore, to ensure the second rib 4 has better structural strength, in one embodiment, the second rib 4 protrudes from the outer peripheral wall of the housing 1, thereby increasing the size of the second rib 4 and increasing the contact area between the second rib 4 and the suspension protrusion 2, thus improving the structural strength of the second rib 4.

[0042] Furthermore, such as Figure 5 and Figure 6 As shown, to avoid the overall size of the suspension protrusion 2 increasing and affecting the casting quality of the suspension protrusion 2 after the first rib 3 and the second rib 4 are connected to it, in one embodiment, the minimum distance between the first rib 3 and the second rib 4 is less than the outer diameter of the suspension protrusion 2. This allows for local thinning at the connection between the suspension protrusion 2 and the outer peripheral wall of the housing 1, increasing the flow rate of molten metal at the connection between the suspension protrusion 2 and the housing 1 during the casting process, improving the overall casting quality of the housing 1, and enhancing the structural strength of the connection between the housing 1 and the suspension protrusion 2.

[0043] like Figure 1 and Figure 2As shown, the housing 1 has a clearance groove 130 to prevent interference during the installation of the engine's transmission structure. Since the clearance groove 130 is located between the countersunk shaft hole 120 and the suspension hole 21, and is situated on the bottom wall of the crankshaft cavity 110, it reduces the structural strength of the portion of the housing 1 near the suspension protrusion 2. The clearance groove 130 and the portion of the countersunk shaft hole 120 near the suspension protrusion 2 have relatively weak structural strength. In this application, the third rib 5 and the fourth rib 6 are both located within the crankshaft cavity 110. The third rib 5 is positioned on the bottom wall of the crankshaft cavity 110, surrounds the outer periphery of the clearance groove 130, and connects to the inner peripheral wall of the crankshaft housing, thereby strengthening the structural portion of the housing 1 near the clearance groove 130. One end of the fourth rib 6 extends in a first direction away from the bottom wall of the crankshaft cavity 110 and connects to the side of the third rib 5 near the inner peripheral wall of the crankshaft cavity 110. The other end of the fourth rib 6, facing away from the crankshaft cavity 110, is at least partially arranged around the auxiliary shaft hole 120 and connects to the side of the third rib 5 away from the inner peripheral wall of the crankshaft cavity 110. The fourth rib 6 connects not only to the third rib 5 but also to the inner peripheral wall of the crankshaft cavity 110 and is arranged around the auxiliary shaft hole 120 to strengthen the local structure of the housing 1 at the auxiliary shaft hole 120 and the clearance groove 130. The third rib 5 and the fourth rib 6 are used to increase the strength of the inner structure of the housing 1 near the suspension protrusion 2, so that the structural strength of the inner and outer sides of the housing 1 at the connection with the suspension protrusion 2 is simultaneously enhanced. This can improve the structure at the suspension hole 21, reduce the risk of cracking at the suspension hole 21, and improve the safety of motorcycle driving.

[0044] Furthermore, such as Figure 1 As shown, to simplify the structure of the third rib 5, in one embodiment, the third rib 5 includes a first connecting segment 51 and a second connecting segment 52, both of which are arranged around the clearance groove 130 to strengthen the structural strength of the outer periphery of the clearance groove 130. The end of the first connecting segment 51 away from the second connecting segment 52 is connected to the inner peripheral wall of the crankshaft cavity 110, and the end of the second connecting segment 52 away from the first connecting segment 51 is connected to the fourth rib 6. The first connecting segment 51 and the second connecting segment 52 are connected to form a whole and are connected to the inner wall of the crankshaft cavity 110 and other rib structures, which can enhance the internal structural strength of the crankshaft cavity 110, thereby improving the structural strength of the suspension protrusion 2 and the inner side of the housing 1.

[0045] Furthermore, such as Figure 1As shown, to simplify the structure of the fourth rib 6, in one embodiment, the fourth rib 6 includes a connecting third connecting segment 61 and a fourth connecting segment 62. One end of the third connecting segment 61 extends in a first direction away from the bottom wall of the crankshaft cavity 110 and is connected to the inner peripheral wall of the crankshaft cavity 110. The other end of the third connecting segment 61, facing away from the bottom wall of the crankshaft cavity 110, is connected to the end of the fourth connecting segment 62. The fourth connecting segment 62 is located on the bottom wall of the crankshaft cavity 110, surrounds the auxiliary shaft hole 120, and its end away from the third connecting segment 61 is connected to the third rib 5. Specifically, the third connecting segment 61 is mainly used to connect the inner peripheral wall of the crankshaft cavity 110 to the bottom wall of the crankshaft cavity 110, and is connected to the second connecting segment 52. The fourth connecting section 62 is mainly used to reinforce the local area of ​​the auxiliary shaft hole 120 near the suspension protrusion 2. The third connecting section 61, the fourth connecting section 62, the first connecting section 51, and the second connecting section 52 form a crisscross structure on the bottom wall of the crankshaft cavity 110 to improve the structural strength of the part of the housing 1 near the suspension protrusion 2, so as to withstand the load transmitted at the suspension hole 21 and reduce the risk of cracking.

[0046] It should be noted that, as Figure 1 and Figure 2 As shown, on a plane perpendicular to the first direction, the first rib 3, the second rib 4 and the outer peripheral wall of the housing 1 can form an approximately triangular structure, the third rib 5 and the inner peripheral wall of the crankshaft cavity 110 form an approximately triangular structure, and the fourth rib 6 and the third rib 5 simultaneously form an approximately triangular structure. Since the triangle has good stability, it improves the structural strength and stress stability of the connection between the inner and outer sides of the housing 1 and the suspension protrusion 2, reduces the risk of structural cracking at the suspension hole 21, and improves the safety of motorcycle driving.

[0047] Furthermore, in one embodiment, the distance from both ends of the third connecting segment 61 to the bottom wall of the crankshaft cavity 110 is greater than the distance from the middle of the third connecting segment 61 to the bottom wall of the crankshaft cavity 110. The third connecting segment 61 forms a variable cross-section reinforcing rib that is low in the middle and high at both ends to increase the stress-bearing area of ​​the third connecting segment 61, thereby improving the structural strength of the fourth reinforcing rib 6.

[0048] Based on the same concept, this application also provides an engine, including a crankcase cover and the aforementioned crankcase. In order to facilitate the sealing of the crankshaft cavity 110 and prevent the transmission structure inside the housing 1 from being affected by external environmental factors, in one embodiment, the bottom wall of the housing 1 away from the crankshaft cavity 110 is provided with a cover profile surface 140 for connecting with the crankcase cover (not shown in the figure). It should be noted that the cover profile surface 140 is provided with multiple threaded holes so that the housing 1 and the crankcase cover are fixedly connected by threaded fasteners (such as screws).

[0049] Based on the same concept, this application also provides a motorcycle, a frame, and the aforementioned engine, with the frame and engine connected via suspension holes 21. The frame and engine are securely assembled through a fixed connection to ensure the structural stability and power transmission efficiency of the entire vehicle during operation.

[0050] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A crankcase, characterized in that include: The housing has a crankshaft cavity and a counterspindle hole inside, with the counterspindle hole located on the bottom wall of the crankshaft cavity; A suspension protrusion is connected to the outer peripheral wall of the housing, and the suspension protrusion has a suspension hole along a first direction; The housing is also provided with a clearance groove, which is located between the secondary shaft hole and the suspension hole; The first rib and the second rib are both located outside the crankshaft cavity. The first rib and the second rib are arranged on both sides of the line connecting the center of the suspension hole and the auxiliary shaft hole. The first rib and the second rib are both used to connect the suspension protrusion and the outer peripheral wall of the housing. The third and fourth ribs are both located within the crankshaft cavity. The third rib is disposed on the bottom wall of the crankshaft cavity, surrounds the outer periphery of the clearance groove, and is connected to the inner peripheral wall of the crankshaft housing. One end of the fourth rib extends in the first direction away from the bottom wall of the crankshaft cavity and is connected to the side of the third rib near the inner peripheral wall of the crankshaft cavity. The other end of the fourth rib, facing away from the crankshaft cavity, at least partially surrounds the auxiliary shaft hole and is connected to the side of the third rib away from the inner peripheral wall of the crankshaft cavity.

2. The crankcase according to claim 1, characterized in that The first rib includes a first sub-rib and a second sub-rib. There are multiple first sub-ribs, which are spaced apart in the first direction. The first sub-ribs are used to connect the suspension protrusion to the outer peripheral wall of the box. The second sub-ribs extend along the first direction and are used to connect two adjacent first sub-ribs.

3. The crankcase according to claim 1, characterized in that The second rib forms a recess between the side of the second rib facing away from the first rib and the outer peripheral wall of the suspension protrusion. The crankcase also includes a fifth rib and a sixth rib, which are respectively provided on opposite sides of the recess. One end of the fifth rib and the sixth rib are connected to the second rib, and the other ends of the fifth rib and the sixth rib facing away from each other are connected to the outer peripheral wall of the suspension protrusion.

4. The crankcase according to claim 1, characterized in that The second rib protrudes from the outer peripheral wall of the box body.

5. The crankcase according to claim 1, characterized in that The minimum distance between the first rib and the second rib is less than the outer diameter of the suspension protrusion.

6. The crankcase according to claim 1, characterized in that The third rib includes a first connecting segment and a second connecting segment, both of which are arranged around the clearance groove. The end of the first connecting segment away from the second connecting segment is connected to the inner peripheral wall of the crankshaft cavity, and the end of the second connecting segment away from the first connecting segment is connected to the fourth rib.

7. The crankcase according to claim 1, characterized in that The fourth reinforcing bar includes a third connecting segment and a fourth connecting segment; One end of the third connecting segment extends along the bottom wall away from the crankshaft cavity in the first direction and is connected to the inner peripheral wall of the crankshaft cavity; the other end of the third connecting segment opposite to the crankshaft cavity is connected to the bottom wall of the crankshaft cavity and its end is connected to one end of the fourth connecting segment. The fourth connecting section is located on the bottom wall of the crankshaft cavity, the fourth connecting section is arranged around the auxiliary shaft hole, and the end of the fourth connecting section away from the third connecting section is connected to the third rib.

8. The crankcase according to claim 7, characterized in that The distance from both ends of the third connecting section to the bottom wall of the crankshaft cavity is greater than the distance from the middle of the third connecting section to the bottom wall of the crankshaft cavity.

9. An engine characterized by, The crankcase includes a crankcase cover and a crankcase as described in any one of claims 1-8, wherein one end of the crankcase body away from the bottom wall of the crankshaft cavity is provided with a closing profile surface for connecting with the crankcase cover.

10. A motorcycle characterized by the fact that It includes a chassis and the engine as described in claim 9, wherein the chassis and the engine are connected via the suspension hole.

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