Crankshaft for two-stroke gasoline engine

Abstract

The utility model discloses a crankshaft for a two-stroke gasoline engine, and relates to the field of cranks, the crankshaft for the two-stroke gasoline engine comprises a semicircular fan-shaped crank, two sides of the semicircular fan-shaped crank are sleeved with round sleeves, each round sleeve is composed of two nesting pieces and a fitting piece, a shaft hole in each fitting piece is opposite to a shaft hole of the semicircular fan-shaped crank, and the two nesting pieces and the fitting piece are connected through a bolt. The two nested parts are symmetrically mounted on the fitting part; compared with a fan-shaped crank without a round sleeve, the crankshaft for the two-stroke gasoline engine has the advantages that the round sleeve is additionally arranged on the semicircular fan-shaped crank, so that part of abrupt change points of geometrical shapes are eliminated under the condition that the crankshaft has the motion characteristics of the semicircular fan-shaped crank, the stress concentration phenomenon of the semicircular fan-shaped crank is improved, and the service life of the crankshaft is prolonged. The fan-shaped crank can bear a larger load, the crank with the round sleeve is additionally arranged, the resistance between the fan-shaped crank and lubricating oil in the box body is obviously reduced, and the periodically changing gas pressure can also be reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of crank, especially a crankshaft for two-stroke gasoline engine. BACKGROUND

[0002] The semi-circular sector connecting rod crank is the core power conversion component of the two-stroke gasoline engine, which converts the linear motion of the piston into the rotary motion of the crankshaft, has the advantages of compact structure, high efficiency and optimized power output, and is widely used in agricultural machinery and small equipment. However, the existing semi-circular sector crank structure has the following defects:

[0003] 1. The crank geometry of the prior art is complex, and the transition fillet, oil hole and other abrupt change regions are prone to stress concentration under high load or high speed, increasing the risk of fatigue fracture. Figure 4 2. The crank is subjected to complex loads during engine operation, including periodic changes in gas pressure, inertial force of reciprocating mass and centrifugal force of rotating mass, etc., and will inevitably collide with oil, generating resistance to the movement of the crank.

[0004] SUMMARY The utility model discloses a crankshaft for two-stroke gasoline engine, which solves the problems of stress concentration and movement resistance caused by collision with oil during movement of the existing semi-circular sector crank.

[0005] In order to make up for the deficiencies of the prior art, the utility model provides a crankshaft for two-stroke gasoline engine, which solves the problems of stress concentration and movement resistance caused by collision with oil during movement of the existing semi-circular sector crank.

[0006] In order to solve the problems of the prior art, the technical scheme of the utility model is as follows:

[0007] A crankshaft for two-stroke gasoline engine, comprising a semi-circular sector crank, both sides of the semi-circular sector crank are sleeved with a round sleeve, the round sleeve is composed of two nesting pieces and a fitting piece, the shaft hole on the fitting piece is opposite to the shaft hole of the semi-circular sector crank, the two nesting pieces are symmetrically installed on the fitting piece, and when the round sleeve is assembled to the outside of the semi-circular sector crank, the two nesting pieces are nested in the two shoulder clearance of the semi-circular sector crank, and the fitting piece is attached to the outer wall of the semi-circular sector crank on the side.

[0008] Preferably, the nesting piece is a plastic piece, the fitting piece is a metal piece, the nesting piece is hollow, the fitting piece is symmetrically provided with a mounting hole, and the nesting piece is formed with a mounting protrusion on one side of the outer wall, the mounting protrusion is inserted into the mounting hole in interference, and the mounting protrusion and the mounting hole realize the assembly of the nesting piece and the fitting piece, so that the two can be stably installed as a whole.

[0009] Preferably, the fitting has a window located between the two nesting parts. When the round sleeve is installed on the semi-circular crank, the window is located on the shoulder side near the semi-circular crank. The window allows the engine oil to fully lubricate the moving parts.

[0010] Compared with the prior art, the advantages of this utility model are as follows:

[0011] Compared to a sector crank without a sleeve, this invention eliminates some abrupt changes in geometry by adding a sleeve to the semi-circular sector crank, thus improving stress concentration and enabling it to withstand greater loads. Furthermore, the addition of the sleeve significantly reduces the resistance between the sector crank and the lubricating oil inside the housing, and also reduces periodically changing gas pressure. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0013] Figure 2 This is one of the schematic diagrams showing the position of the nested component of this utility model.

[0014] Figure 3 This is the second schematic diagram of the nesting component position of this utility model.

[0015] Figure 4 This is a schematic diagram of the prior art of this utility model.

[0016] Reference numerals: 1. Semicircular fan-shaped crank; 2. Circular sleeve; 3. Nesting part; 4. Fitting part; 5. Mounting hole; 6. Mounting protrusion; 7. Window. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0018] Please see Figures 1 to 3 This embodiment provides a crankshaft for a two-stroke gasoline engine, including a semi-circular fan-shaped crank 1. Both sides of the semi-circular fan-shaped crank 1 are fitted with circular sleeves 2. The circular sleeves 2 are composed of two nesting parts 3 and a fitting part 4. The shaft hole on the fitting part 4 is opposite to the shaft hole of the semi-circular fan-shaped crank 1. The two nesting parts 3 are symmetrically installed on the fitting part 4.

[0019] The circular sleeve 2 reduces the disturbance of airflow in the crankcase by the semi-circular crank and also reduces the resistance of the oil on the fan-shaped crank when it rotates.

[0020] The nesting part 3 is a plastic part, and it is made of wear-resistant and high-temperature resistant plastic material. The bonding part 4 is a metal part, and it is made of wear-resistant metal material. The nesting part 3 is hollow. The hollow structure of the wear-resistant and high-temperature resistant plastic part reduces its weight. At high temperatures, the plastic part can expand slightly and fit tightly to the crank.

[0021] The wear-resistant metal fitting 4 covers the outer wall of the crank, and its rigid support complements the elasticity of the nesting part 3, making the cross-sectional dimension changes of the geometrically abrupt areas such as the crank transition fillet and lubricating oil hole more gradual, and significantly reducing the peak stress.

[0022] The fitting part 4 has symmetrically opened mounting holes 5, and the outer wall of one side of the nesting part 3 has a mounting protrusion 6. The mounting protrusion 6 is interference-fitted into the mounting hole 5. The mounting protrusion 6 and the mounting hole 5 realize the assembly of the nesting part 3 and the fitting part 4, so that the two can be stably installed as one.

[0023] When the round sleeve 2 is assembled on the outside of the semi-circular fan-shaped crank 1, the two nesting parts 3 are nested in the two shoulder gaps of the semi-circular fan-shaped crank 1, and the fitting part 4 is attached to the outer wall of the semi-circular fan-shaped crank 1 on the side. A window 7 is provided on the fitting part 4 at the position between the two nesting parts 3. When the round sleeve 2 is installed on the semi-circular fan-shaped crank 1, the window 7 is located on the side close to the shoulder of the semi-circular fan-shaped crank 1. The setting of the window 7 allows the engine oil to fully lubricate the moving parts.

[0024] Compared to a sector crank without the sleeve 2, this invention eliminates some abrupt changes in geometry by adding a sleeve 2 to the semi-circular sector crank 1, thus improving the stress concentration phenomenon and enabling it to withstand greater loads. Furthermore, the addition of the sleeve 2 significantly reduces the resistance of the sector crank to the lubricating oil inside the housing, and also reduces the periodically changing gas pressure.

[0025] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A crankshaft for a two-stroke gasoline engine comprising half-round sectorial cranks (1), characterised in that, Both sides of the semi-circular sector crank (1) are sleeved with a round sleeve (2), the round sleeve (2) is composed of two nesting pieces (3) and a fitting piece (4), the shaft hole on the fitting piece (4) is opposite to the shaft hole of the semi-circular sector crank (1), and the two nesting pieces (3) are symmetrically installed on the fitting piece (4).

2. The crankshaft for a two-cycle gasoline engine according to claim 1, characterized in that, The nesting piece (3) is a plastic piece.

3. The crankshaft for a two-cycle gasoline engine according to claim 2, characterized in that, The fitting piece (4) is a metal piece.

4. The crankshaft for a two-cycle gasoline engine according to claim 3, characterized in that, The nesting piece (3) is provided with a hollow.

5. The crankshaft for a two-cycle gasoline engine according to claim 1, wherein Symmetrical mounting holes (5) are formed on the fitting piece (4), mounting protrusions (6) are formed on the outer wall of one side of the nesting piece (3), and the mounting protrusions (6) are inserted into the mounting holes (5) in an interference fit.

6. The crankshaft for a two-cycle gasoline engine according to claim 5, characterized in that, Windows (7) are formed on the fitting piece (4) between the two nesting pieces (3), and when the round sleeve (2) is installed on the semi-circular sector crank (1), the windows (7) are located on the side close to the shoulder of the semi-circular sector crank (1).

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