A crankshaft for a motorcycle engine

Abstract

The utility model relates to motorcycle engine parts technical field, concretely relates to a crankshaft for motorcycle engine, including semicircle key, timing sprocket, rolling bearing, left crank, connecting rod, needle roller bearing, crank pin, right crank and balance weight adjusting gasket, timing sprocket rotates through chain drive camshaft, and rolling bearing supports the main journal of crankshaft, and the rotary motion of crankshaft is converted into rolling friction, reduces running resistance and wear, improves the smoothness of crankshaft operation, left crank connects main journal and connecting rod journal, and reciprocating force of piston connecting rod is transmitted and is converted into rotary moment, and the function of integrated counterweight is simultaneously, and connecting rod connects piston and crank connecting rod journal, and reciprocating linear motion of piston is converted into the rotary motion of crankshaft, and crank pin is connecting rod journal of crankshaft, and reciprocating force of connecting rod is transmitted, and right crank and left crank are symmetrically distributed, and jointly constitute the crank arm structure of crankshaft, and crank pin bears the function of counterweight, torque transmission.

Description

Technical Field

[0001] This utility model relates to the technical field of motorcycle engine components, and in particular to a crankshaft for a motorcycle engine. Background Technology

[0002] As the core power transmission component of a motorcycle engine, the crankshaft converts the reciprocating linear motion transmitted by the piston and connecting rod into rotational motion, while driving auxiliary mechanisms such as the camshaft and generator. It is a key component that determines the engine's power output, operational stability, and service life. Motorcycle engines (especially small and medium displacement models) are characterized by their compact structure, wide speed range (typically 3000-10000 rpm), and frequent fluctuations in operating conditions (alternating between starting, acceleration, idling, and high-speed cruising).

[0003] The prior art CN205780245U discloses a motorcycle engine crankshaft, wherein the crankshaft has at least one support body formed along the axial direction for supporting the crankcase of the engine and transmitting the force, and the support body is spaced apart from the connecting rod journal of the crankshaft; the structure is compact and can effectively bear the large impact force of the piston connecting rod and efficiently and smoothly convert it into the kinetic energy of the engine movement.

[0004] However, the aforementioned motorcycle engine crankshaft dynamic balance optimization is insufficient, making it difficult to completely offset multi-order inertial forces, resulting in significant vibration during engine operation, which affects driving comfort and the service life of components. Utility Model Content

[0005] The purpose of this invention is to provide a crankshaft for a motorcycle engine, which aims to solve the problem of insufficient dynamic balance optimization of traditional motorcycle engine crankshafts, resulting in excessive vibration during engine operation.

[0006] To achieve the above objectives, this utility model provides a crankshaft for a motorcycle engine, comprising a semi-circular key, a timing sprocket, rolling bearings, a left crank, a connecting rod, a needle roller bearing, a crank pin, a right crank, and balance weight adjusting shims; the semi-circular key is mounted on one end of the left crank, the right crank is located on the end of the left crank away from the semi-circular key, the connecting rod is located between the left and right cranks, the crank pin is mounted between the left and right cranks and passes through the connecting rod, the timing sprocket is mounted on the outside of the left crank, the rolling bearings are respectively mounted on the left and right cranks and located on both sides of the crank pin, the needle roller bearing is located between the left and right cranks, and the balance weight adjusting shims are respectively mounted on the side of the left and right cranks away from the crank pin.

[0007] The crankshaft for the motorcycle engine also includes an oil passage filter screen, which is fixedly connected to the right crank and located inside the right crank.

[0008] The rolling bearing has a wear-resistant shim, which is located on the side of the rolling bearing near the crank pin.

[0009] The left crank and the right crank have a triangular waist-shaped structure, and the left crank and the right crank have counterweight holes on both sides.

[0010] This utility model discloses a crankshaft for a motorcycle engine. The semi-circular key connects the main journal and the timing sprocket, transmitting torque while achieving circumferential positioning and preventing relative rotation between the sprocket and the crankshaft journal. The timing sprocket drives the camshaft to rotate via a chain, ensuring that the valve opening / closing timing is synchronized with the piston movement. The rolling bearing supports the crankshaft's main journal, converting the crankshaft's rotational motion into rolling friction, reducing operating resistance and wear, and improving the smoothness of crankshaft operation. The left crankshaft connects the main journal and the connecting rod journal, transmitting the reciprocating force of the piston and connecting rod and converting it into rotational torque. It also integrates a counterweight function (counteracting part of the inertial force). The connecting rod connects the piston and the crankshaft connecting rod journal, transmitting the reciprocating force of the piston and connecting rod into rotational torque. The reciprocating linear motion of the piston is converted into the rotational motion of the crankshaft. The needle roller bearing adopts a needle roller structure (large contact area) to reduce the friction and wear between the connecting rod and the crankshaft. The crank pin, which is the connecting rod journal of the crankshaft, is the mounting reference of the connecting rod and transmits the reciprocating force of the connecting rod. The right crank and the left crank are symmetrically distributed and together form the crank arm structure of the crankshaft. The crank pin bears the role of counterweight and torque transmission. By increasing or decreasing the number / thickness of the balance block adjusting shims (thin metal shims, 0.1-0.5mm thick), the mass distribution of the crankshaft can be finely adjusted, reducing the dynamic balancing adjustment cost of the crankshaft and solving the problem of insufficient dynamic balancing optimization of traditional motorcycle engine crankshafts, which leads to large vibrations during engine operation. Attached Figure Description

[0011] To make the technical solution and advantages of this application clearer, the embodiments of this application will be described in further detail below.

[0012] Figure 1 This is a longitudinal sectional view of a crankshaft for a motorcycle engine provided by this utility model.

[0013] Figure 2 This is a side view of a crankshaft for a motorcycle engine provided by this utility model.

[0014] In the diagram: 1-Semicircular key, 2-Timing sprocket, 3-Rolling bearing, 4-Left crank, 5-Connecting rod, 6-Needle roller bearing, 7-Crank pin, 8-Right crank, 9-Balance weight adjusting shim, 10-Oil passage filter, 11-Wear-resistant shim, 12-Counterweight hole. Detailed Implementation

[0015] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0016] Please see Figures 1 to 2 This utility model provides a crankshaft for a motorcycle engine, including a semi-circular key 1, a timing sprocket 2, rolling bearings 3, a left crank 4, a connecting rod 5, a needle roller bearing 6, a crank pin 7, a right crank 8, and balance weight adjusting shims 9. The semi-circular key 1 is assembled at one end of the left crank 4, the right crank 8 is located at the end of the left crank 4 away from the semi-circular key 1, the connecting rod 5 is located between the left crank 4 and the right crank 8, the crank pin 7 is assembled between the left crank 4 and the right crank 8 and passes through the connecting rod 5, the timing sprocket 2 is assembled on the outside of the left crank 4, the rolling bearings 3 are respectively assembled on the left crank 4 and the right crank 8 and located on both sides of the crank pin 7, the needle roller bearing 6 is located between the left crank 4 and the right crank 8, and the balance weight adjusting shims 9 are respectively assembled on the side of the left crank 4 and the right crank 8 away from the crank pin 7.

[0017] In this embodiment, the semi-circular key 1 connects the main journal and the timing sprocket 2, transmitting torque while achieving circumferential positioning to prevent relative rotation between the sprocket and the crankshaft journal. The timing sprocket 2 drives the camshaft to rotate via a chain, ensuring that the valve opening / closing timing is synchronized with the piston movement. The rolling bearing 3 supports the crankshaft's main journal, converting the crankshaft's rotational motion into rolling friction, reducing operating resistance and wear, and improving the smoothness of crankshaft operation. The left crank 4 connects the main journal and the connecting rod journal, transmitting the reciprocating force of the piston and connecting rod and converting it into rotational torque, while also integrating a counterweight function (counteracting part of the inertial force). The connecting rod 5 connects the piston and the crankshaft connecting rod journal, converting the piston's reciprocating linear motion... The motion is converted into the rotational motion of the crankshaft. The needle roller bearing 6 adopts a needle roller structure (large contact area) to reduce the friction and wear between the connecting rod 5 and the crankshaft. The crank pin 7 is the connecting rod journal of the crankshaft and serves as the mounting reference for the connecting rod 5, transmitting the reciprocating force of the connecting rod. The right crank 8 and the left crank 4 are symmetrically distributed, together forming the crank arm structure of the crankshaft. Together with the crank pin 7, they bear the functions of counterweight and torque transmission. By increasing or decreasing the number / thickness of the balance block adjusting shims 9 (thin metal shims, 0.1-0.5mm thick), the mass distribution of the crankshaft can be finely adjusted, reducing the dynamic balancing adjustment cost of the crankshaft and solving the problem of insufficient dynamic balancing optimization of traditional motorcycle engine crankshafts, which leads to large vibrations during engine operation.

[0018] Furthermore, the crankshaft for the motorcycle engine also includes an oil passage filter 10, which is fixedly connected to the right crank 8 and located inside the right crank 8.

[0019] In this embodiment, the oil passage filter 10 is used to filter out tiny impurities (such as metal shavings and deposits) in the lubricating oil, preventing impurities from entering the friction surface between the needle roller bearing 6 and the crank pin 7, thus preventing bearing failure and increased wear.

[0020] Furthermore, the rolling bearing 3 has a wear-resistant shim 11, which is located on the side of the rolling bearing 3 near the crank pin 7.

[0021] In this embodiment, the wear-resistant gasket 11 (made of copper alloy or polytetrafluoroethylene, with a thickness of 0.2-0.3mm) is used to isolate the direct metal-to-metal contact between the crankshaft and the bearing, avoiding frictional wear caused by slight axial movement when the crankshaft rotates; at the same time, it can compensate for assembly clearance, reduce the impact of vibration, and improve the fit stability between the bearing and the crankshaft.

[0022] Furthermore, the left crank 4 and the right crank 8 have a triangular waist-shaped structure, and the left crank 4 and the right crank 8 have counterweight holes 12 on both sides.

[0023] In this embodiment, the triangular waist structure and the design of the counterweight hole 12 reduce the weight on both sides, ensuring the dynamic balance of the crank.

[0024] The above-disclosed embodiments are merely preferred embodiments of a crankshaft for a motorcycle engine and should not be construed as limiting the scope of this application. Those skilled in the art will understand that all or part of the processes for implementing the above embodiments and equivalent variations made in accordance with the claims of this application are still within the scope of this application.

Claims

1. A crankshaft for a motorcycle engine, characterized in that, Includes a semi-circular key, timing sprocket, rolling bearing, left crank, connecting rod, needle roller bearing, crank pin, right crank, and balance weight adjusting shims; The semi-circular key is fitted to one end of the left crank, the right crank is located at the end of the left crank away from the semi-circular key, the connecting rod is located between the left and right cranks, the crank pin is fitted between the left and right cranks and passes through the connecting rod, the timing sprocket is fitted to the outside of the left crank, the rolling bearings are respectively fitted to the left and right cranks and located on both sides of the crank pin, the needle roller bearing is located between the left and right cranks, and the balance weight adjusting shims are respectively fitted to the left and right cranks on the side away from the crank pin.

2. The crankshaft for a motorcycle engine as described in claim 1, characterized in that, The crankshaft for the motorcycle engine also includes an oil passage filter screen, which is fixedly connected to the right crank and located inside the right crank.

3. The crankshaft for a motorcycle engine as described in claim 1, characterized in that, The rolling bearing has a wear-resistant shim located on the side of the rolling bearing near the crank pin.

4. The crankshaft for a motorcycle engine as described in claim 1, characterized in that, The left crank and the right crank have a triangular waist-shaped structure, and the left crank and the right crank have counterweight holes on both sides.

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