Crank connecting rod assembly of double-cylinder motorcycle engine

Abstract

The utility model discloses a double-cylinder motorcycle engine crank connecting rod assembly which comprises a left crank, a right crank and a crank pin, the left crank and the right crank are connected through the eccentrically-arranged crank pin, and a left crank shaft which is integrally formed with the left crank and coaxially arranged with the left crank is arranged on the outer side wall of the left crank. A right crank shaft integrally formed with the right crank and coaxially arranged with the right crank is arranged on the outer side wall of the right crank; the diameter of the crank pin is equal to or larger than that of the left crank shaft or the right crank shaft, the crank pin is sleeved with two piston connecting rods, the two piston connecting rods are arranged in the same direction, and ball bearings are arranged between the two piston connecting rods and the crank pin in a clearance fit mode; a left bearing and a right bearing which are coaxial with the right crank shaft and the left crank shaft are respectively sleeved on the right crank shaft and the left crank shaft, the left bearing is arranged close to the outer side of the left crank, the right bearing is arranged on the outer side of the right crank, and a balance shaft driving gear is in spline fit between the right bearing and the right crank; and a timing driving chain wheel in interference fit with the left bearing is sleeved outside the left bearing in the middle of the left crankshaft.

Description

Technical Field

[0001] The utility model relates to the field of twin-cylinder motorcycle engines, in particular to a crank-connecting rod assembly of a twin-cylinder motorcycle engine. Background Art

[0002] The motorcycle crankshaft-connecting rod assembly is a crucial moving component that enables the motorcycle engine's operating cycle and energy conversion. The crankshaft-connecting rod assembly of a traditional single-cylinder engine consists of a left crank and a right crank. For ease of connection, the left and right cranks are connected by a crank pin, which typically forms an interference fit with the crank pin. In a twin-cylinder engine, to ensure strength, the crank in the crank-connecting rod mechanism consists of a gear shaft and two cranks rigidly connected to the gear shaft. While this structure provides strength, it is difficult to disassemble and assemble (as exemplified by the twin-cylinder motorcycle crank assembly disclosed in Chinese Patent Application No. 2023222918439). Therefore, the applicant sought to design a twin-cylinder motorcycle engine crank-connecting rod assembly that is easy to assemble and disassemble, structurally stable, and highly robust. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a crank-connecting rod assembly for a twin-cylinder motorcycle engine, so as to solve the problem that the crank-connecting rod mechanism of the existing twin-cylinder motorcycle engine has a complex structure and is inconvenient to disassemble and assemble.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The camshaft is connected to the left crankshaft by a camshaft, and the camshaft is connected to the right crankshaft by a camshaft. In this way, during assembly, the left crank, left crankshaft, left bearing, and timing drive sprocket are assembled as a single unit; the right crank, right crankshaft, right bearing, and balance shaft drive gear are assembled as a single unit; and the two piston connecting rods and crankpin are assembled as a single unit. This allows for easy assembly by simply interfering the left crank with the left end of the crankpin, and the right crank with the right end of the crankpin. Furthermore, the crankpin can be disassembled separately during maintenance. When the crankpin is applied to a twin-cylinder mechanism, its diameter is equal to or greater than that of the crankshaft. Compared to conventional crankpins, its structural strength is sufficient to support the movement of the two piston connecting rods. After interfering with the left and right cranks, the crankpin, left crankshaft, and right crankshaft form a single shaft with coaxial ends and an eccentric center. This three-section connection method for forming the shaft provides a simpler assembly structure and improved structural strength compared to conventional twin-cylinder crank-connecting rod mechanisms.

[0006] Furthermore, a lubricating oil inlet channel is provided axially in the middle of the left crankshaft, and a main lubricating oil channel connected to the lubricating oil inlet channel is provided in the middle of the crankpin. The main lubricating oil channel is coaxial with the crankpin, and two radial oil injection holes for lubricating the ball bearings are provided in the two ball bearing assembly sections of the crankpin. Thus, with the coaxial lubricating oil inlet channel provided on the left crankshaft, the oil channel remains unchanged as the left crankshaft rotates. Lubricating oil is introduced through the lubricating oil inlet channel, then enters the connected main lubricating oil channel and is ejected from the radial oil injection holes to lubricate the ball bearings of the two piston connecting rods, preventing severe wear between the connecting rods and the crankpin.

[0007] Furthermore, oil seals with transverse oil spray holes in the middle are installed at both ends of the main lubricating oil channel. This prevents oil from overflowing from the ends of the main lubricating oil channel. The transverse oil spray holes in the oil seals correspond to the left and right bearings, spraying lubricating oil onto the bearings to lubricate them. This lubrication method is simpler to set up than adding additional oil channels.

[0008] Furthermore, the lubricating oil introduction channel is connected to the main lubricating oil passage via an oblique oil guide channel. The oblique oil guide channel comprises a first channel provided on the left crankshaft and a second channel provided on the crankpin, with the ends of the first and second channels correspondingly connected. An end oil seal is provided at one end of the lubricating oil introduction channel, adjacent to the crankpin. Thus, the oblique oil guide channel is capable of directing lubricating oil from the lubricating oil introduction channel into the main lubricating oil passage. One end of the oblique oil guide channel is provided at the end of the left crankshaft, and the other end is provided on the crankpin. The left crankshaft and crankpin are connected by an interference fit of the left crank at the end of the left crankshaft, enabling synchronous rotation. Thus, during operation, the channels remain synchronized and connected.

[0009] Furthermore, a press-fit hole is provided on each of the left and right cranks, and the left and right ends of the crank pin are respectively connected to the left and right cranks by press-fit interference fit. In this way, by providing a press-fit hole eccentric to the crank shaft for assembly with the crank pin, assembly is more convenient.

[0010] Furthermore, two locating shoulders are provided on the crankpin, with the piston connecting rod assembled between the locating shoulders and the corresponding left or right crank. These locating shoulders can limit the piston connecting rod, define its assembly position, and ensure that the piston connecting rod always remains in the set position during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A perspective view of a crank-connecting rod assembly of a twin-cylinder motorcycle engine in an embodiment;

[0012] Figure 2 A side view of a crank-connecting rod assembly of a twin-cylinder motorcycle engine in an embodiment;

[0013] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure after the AA cross-sectional view in the middle is rotated 90°;

[0014] Figure 4 1 is an exploded view of the crank-connecting rod assembly of a twin-cylinder motorcycle engine in an embodiment. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the utility model for protection, but merely represents selected embodiments of the present invention. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0016] It should be noted that similar reference numerals and letters denote similar items in the following figures. Therefore, once an item is defined in one figure, it does not require further definition or explanation in subsequent figures. In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or relationships, are based on the positions or relationships shown in the figures, or the positions or relationships in which the inventive product is typically placed when in use. These terms are intended solely for ease of description and simplification of the present invention and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance. Furthermore, terms such as "horizontal" and "vertical" do not imply that a component must be absolutely horizontal or overhanging, but rather may be slightly tilted. For example, "horizontal" simply refers to a direction that is more horizontal than "vertical," and does not imply that the structure must be completely horizontal, but rather may be slightly tilted. It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0017] like Figure 1-Figure 4As shown, the present embodiment provides a crank-connecting rod assembly of a twin-cylinder motorcycle engine, comprising a left crank 1, a right crank 2 and a crank pin 3. The left crank 1 and the right crank 2 are connected by an eccentrically arranged crank pin 3. A left crank shaft 11 integrally formed and coaxially arranged with the left crank 1 is provided on the outer wall of the left crank 1, and a right crank shaft 21 integrally formed and coaxially arranged with the right crank 2 is provided on the outer wall of the right crank 2. The diameter of the crank pin 3 is equal to or greater than the diameter of the left crank shaft 11 or the right crank shaft 21. Two piston connecting rods are sleeved on the crank pin 3. Rod 4, the two piston connecting rods 4 are arranged in the same direction, and a ball bearing 5 is clearance-fitted between the two piston connecting rods 4 and the crank pin 3; a left bearing 6 and a right bearing 7 are respectively provided on the right crankshaft 21 and the left crankshaft 11, which are coaxially arranged therewith. The left bearing 6 is arranged close to the outside of the left crank 1, and the right bearing 7 is placed on the outside of the right crank 2, and a balance shaft driving gear 9 is spline-fitted between the right bearing 7 and the right crank 2; a timing driving sprocket 8 with an interference fit therewith is provided on the middle part of the left crankshaft 11 and the left bearing 6. Thus, during assembly, the left crank 1, the left crankshaft 11, the left bearing 6, and the main driving sprocket are assembled into a whole, the right crank 2, the right crankshaft 21, the right bearing 7, and the balance shaft driving gear 9 are assembled into a whole, and the two piston connecting rods 4 and the crank pin 3 are assembled into a whole. Therefore, during assembly, it is only necessary to interference fit the left crank 1 with the left end of the crank pin 3, and the right crank 2 with the right end of the crank pin 3 to complete the overall assembly, which is very convenient. At the same time, it can be disassembled as three parts during maintenance. After the crank pin 3 is applied to the double cylinder, its diameter is equal to or greater than the crankshaft diameter. Compared with the traditional crank pin 3, its structural strength can meet the strength of the movement of the two piston connecting rods 4. After interference fitting with the left crank 1 and the right crank 2, the crank pin 3, the left crankshaft 11, and the right crankshaft 21 form a shaft body with coaxial ends and eccentric center. This three-section connection method of forming the shaft body is simpler to assemble and has better structural strength than the traditional two-cylinder crank-connecting rod mechanism. The interference fit between the timing drive sprocket 8 and the left crankshaft 11 is more cost-effective and simpler to manufacture than the traditional spline fit.

[0018] Furthermore, a lubricating oil inlet channel 12 is provided axially in the middle of the left crankshaft 11. A main lubricating oil passage 32, connected to the lubricating oil inlet channel 12, is provided in the middle of the crankpin 3. The main lubricating oil passage 32 is coaxially arranged with the crankpin 3, and two radial oil injection holes for lubricating the ball bearings 5 are provided in the assembly section of the two ball bearings 5 of the crankpin 3. Thus, with the coaxial lubricating oil inlet channel 12 provided on the left crankshaft 11, the oil passage remains unchanged as the left crankshaft 11 rotates. Lubricating oil is introduced through the lubricating oil inlet channel 12, then enters the connected main lubricating oil passage 32, and is ejected from the radial oil injection holes to lubricate the ball bearings 5 of the two piston connecting rods 4, thereby preventing severe wear between the connecting rods and the crankpin 3.

[0019] Furthermore, oil seals with transverse oil spray holes in the middle are installed at both ends of the main lubricating oil channel 32. This prevents lubricating oil from overflowing from the ends of the main lubricating oil channel 32. The transverse oil spray holes in the oil seals correspond to the left and right bearings 6 and 7, spraying lubricating oil onto the bearings to lubricate them. This lubrication method is simpler to set up than adding additional oil channels.

[0020] Furthermore, the lubricating oil introduction channel 12 is connected to the main lubricating oil passage 32 via an oblique oil guide passage. The oblique oil guide passage comprises a first channel 13 provided on the left crankshaft 11 and a second channel 33 provided on the crankpin 3. The ends of the first channel 13 and the second channel 33 are correspondingly connected. An end oil seal is provided at one end of the lubricating oil introduction channel 12 near the crankpin 3. Thus, the oblique oil guide passage can guide lubricating oil from the lubricating oil introduction channel 12 into the main lubricating oil passage 32. One end of the oblique oil guide passage is provided at the end of the left crankshaft 11, and the other end is provided on the crankpin 3. The left crankshaft 11 and the crankpin 3 are connected by an interference fit with the left crank 1 at the end of the left crankshaft 11, enabling synchronous rotation. Thus, during operation, the above-mentioned passages always remain synchronized and connected.

[0021] Furthermore, a press-fit hole is provided on each of the left crank 1 and the right crank 2, and the left and right ends of the crank pin 3 are respectively connected to the left crank 1 and the right crank 2 by press-fit interference fit. In this way, by providing a press-fit hole eccentric to the crank shaft for assembly with the crank pin 3, assembly is more convenient.

[0022] Furthermore, two locating shoulders 31 are provided on the crankpin 3. The piston connecting rod is assembled between the locating shoulders 31 and the corresponding left crank 1 or right crank 2. A thrust washer is provided between the left crank 1 and the left locating shoulder 31, on both sides of the left piston connecting rod 4, and between the right crank 2 and the right locating shoulder 31, on both sides of the right piston connecting rod 4. The locating shoulders 31 limit the piston connecting rod, defining its assembly position and ensuring that the piston connecting rod remains in the set position during operation. The thrust washers prevent friction between the piston connecting rod 4 and the shoulders and the left crank 1 or right crank 2, effectively extending the service life of the left crank 1, right crank 2, and crankpin 3.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Ordinary technicians in this field should understand that those modifications or equivalent replacements of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A crank-connecting rod assembly for a twin-cylinder motorcycle engine, comprising a left crank, a right crank, and a crank pin, wherein the left crank and the right crank are connected by an eccentrically disposed crank pin, a left crankshaft integrally formed and coaxially disposed with the left crank is provided on the outer side wall of the left crank, and a right crankshaft integrally formed and coaxially disposed with the right crank is provided on the outer side wall of the right crank; characterized in that: The diameter of the crank pin is equal to or greater than the diameter of the left crankshaft or the right crankshaft, and two piston connecting rods are sleeved on the crank pin. The two piston connecting rods are arranged in the same direction, and ball bearings are clearance-fitted between the two piston connecting rods and the crank pin; a left bearing and a right bearing coaxially arranged therewith are sleeved on the right crankshaft and the left crankshaft respectively, the left bearing is arranged close to the outer side of the left crank, and the right bearing is placed on the outer side of the right crank, and a balance shaft driving gear is spline-fitted between the right bearing and the right crank; a timing driving sprocket with an interference fit therewith is provided in the middle of the left crankshaft and on the outer sleeve of the left bearing.

2. The crank-connecting rod assembly of a twin-cylinder motorcycle engine according to claim 1, characterized in that: A lubricating oil inlet channel is provided in the middle of the left crankshaft along its axial direction, and a main lubricating oil channel connected to the lubricating oil inlet channel is provided in the middle of the crank pin. The main lubricating oil channel is coaxially arranged with the crank pin, and two radial oil spray holes for lubricating the ball bearings are provided in the two ball bearing assembly sections of the crank pin.

3. The crank-connecting rod assembly of a twin-cylinder motorcycle engine according to claim 2, characterized in that: Oil seals with transverse oil spray holes in the middle are provided at both ends of the main lubricating oil channel.

4. The crank-connecting rod assembly of a twin-cylinder motorcycle engine according to claim 2 or 3, characterized in that: The lubricating oil introduction channel is connected to the main lubricating oil channel through an oblique oil guide channel. The oblique oil guide channel consists of a first channel provided on the left crankshaft and a second channel provided on the crank pin, and the ends of the first channel and the second channel are correspondingly connected; an end oil seal is provided at one end of the lubricating oil introduction channel close to the crank pin.

5. The crank-connecting rod assembly of a twin-cylinder motorcycle engine according to claim 4, characterized in that: A press-fit hole is provided on each of the left crank and the right crank, and the left and right ends of the crank pin are respectively connected to the left crank and the right crank through press-fit interference fit.

6. The crank-connecting rod assembly of a twin-cylinder motorcycle engine according to claim 1, 2, 3 or 5, characterized in that: Two positioning shoulders are provided on the crank pin, and the piston connecting rod is assembled between the positioning shoulders and the left crank or the right crank on the corresponding side.

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