Clutch speed change structure of motorcycle engine

Abstract

The invention belongs to the technical field of motorcycle engines, and relates to a clutch speed change structure of a motorcycle engine, which comprises a crankshaft, a driving wheel set and a driven wheel set, the driving wheel set is driven by the crankshaft, the driving wheel set and the driven wheel set are in transmission connection through a belt, and the crankshaft is sleeved with a clutch assembly and a speed change assembly. The clutch assembly and the speed change assembly form the driving wheel set, the clutch assembly comprises a clutch disc, a shoe block and a clutch cover, the speed change assembly comprises a fixed disc, a movable disc and a pulley ball, a V-shaped groove in friction connection with a belt is formed between the clutch cover and the movable disc, the clutch cover transmits crankshaft torque to drive the belt to rotate, and the pulley ball is connected with the movable disc. The movable disc slides in the axial direction to change the pitch circle of the belt so as to change the speed. According to the clutch speed change structure of the motorcycle engine, the structure is more compact, clutch response is faster, and safety and passing ability are better.

Description

Technical Field

[0001] The present invention belongs to the technical field of motorcycle engines and relates to a clutch shifting structure of a motorcycle engine. Background Art

[0002] The CVT transmission system of a scooter mainly uses a V-belt in combination with front and rear disc groups as a speed-changing and transmission mechanism. In a traditional transmission system, the driving disc group generally includes a primary pulley, primary weights, and a fan disc. When the engine is at a low speed, the primary weights do not have enough centrifugal force to be thrown out, so there is a large distance between the two discs. As a result, the belt is also in a position closer to the axis to simulate a low gear and a high reduction ratio state. During the acceleration process, when the engine speed increases, the primary weights will be thrown outwards, and at the same time, the primary pulley will be pushed outwards, shortening the distance between the two discs. After the distance between the two discs is shortened, the V-belt is also pushed outwards by the two discs to simulate a high gear and a low reduction ratio state, enabling the vehicle speed to increase. The driven disc group generally includes a driven wheel and a centrifugal clutch device. When the engine speed reaches a certain level, the centrifugal force of the shoe overcomes the spring tension and is thrown outwards to contact the clutch drum, thereby engaging the power and driving the rear wheel to rotate. At low speeds, the spring pulls the shoe back to disengage the power and achieve no forward movement at idle speed.

[0003] The disadvantages of the existing structure are as follows: ① The rotational speed of the driven wheel is relatively low, the clutch response is slow, and when the torque is too large, slipping often occurs due to insufficient rotational speed; ② The weight at the rear end of the gearbox is large, and the safety is poor; ③ The structure is complex and the combined assembly is relatively difficult; ④ As long as the engine crankshaft rotates, its belt will operate, thus shortening the belt life. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a clutch shifting structure of a motorcycle engine, making the structure more compact, the clutch response faster, and the safety and passability better.

[0005] To solve the above technical problems, the object of the present invention is achieved by the following technical solutions:

[0006] A clutch and transmission structure for a motorcycle engine, comprising a crankshaft, a driving wheel set and a driven wheel set. The driving wheel set is driven by the crankshaft, and the driving wheel set and the driven wheel set are connected by belt drive. A clutch assembly and a transmission assembly are sleeved on the crankshaft. The clutch assembly and the transmission assembly form the driving wheel set. The clutch assembly includes a clutch disc, shoe blocks and a clutch cover. The clutch disc is key-connected to the crankshaft, and the clutch cover is connected to the clutch disc by shoe blocks driven by centrifugal force. The transmission assembly includes a fixed disc, a movable disc and weight balls. The fixed disc is fixedly connected to the crankshaft, the movable disc is slidably connected to the crankshaft, and the weight balls are arranged in the track of the movable disc and drive the movable disc to slide by centrifugal force. A V-shaped groove for frictionally connecting with the belt is formed between the clutch cover and the movable disc. The clutch cover transmits the torque of the crankshaft to drive the belt to rotate, and the movable disc slides axially to change the pitch circle of the belt for speed change.

[0007] In the above-mentioned clutch and transmission structure for a motorcycle engine, a cooling fan is sleeved on the crankshaft. The cooling fan rotates with the crankshaft for heat dissipation, and the cooling fan acts on the clutch assembly and the transmission assembly at the same time.

[0008] In the above-mentioned clutch and transmission structure for a motorcycle engine, the crankshaft is provided with a first bushing through a shaft shoulder. An involute spline for key-connecting with the clutch disc is arranged on the crankshaft outside the first bushing, and the inner end face of the clutch disc abuts against the outer end face of the first bushing.

[0009] In the above-mentioned clutch and transmission structure for a motorcycle engine, a gasket and a thrust bearing are sequentially sleeved on the crankshaft outside the clutch disc. The two thrust washers of the thrust bearing respectively abut against the gasket and the clutch cover.

[0010] In the above-mentioned clutch and transmission structure for a motorcycle engine, a plurality of shoe blocks are provided and distributed circumferentially. The inner side of the shoe block is hinged to the clutch disc through a pin shaft, and the outer side is covered with friction material. A clutch spring for driving the shoe block to rotate inward is arranged between the shoe block and the pin shaft.

[0011] In the above-mentioned clutch and transmission structure for a motorcycle engine, preferably, under the action of centrifugal force, the minimum engagement speed of the shoe block with the clutch cover is 2600 rpm.

[0012] In the above-mentioned clutch and transmission structure for a motorcycle engine, a second bushing is sleeved on the crankshaft outside the clutch cover. The fixed disc abuts against the outer end face of the second bushing to form an axial limiting structure, and the movable disc is slidably arranged on the second bushing.

[0013] In the above-mentioned clutch and speed change structure of a motorcycle engine, a locking nut is screwed on the outer end of the crankshaft. After the locking nut is tightened, it axially presses a first bushing, a clutch disc, a gasket, a thrust bearing, a clutch cover, a second bushing and a fixing disc in sequence.

[0014] In the above-mentioned clutch and speed change structure of a motorcycle engine, the driven wheel set includes a driven fixing disc and a driven movable disc. The driven movable disc is slidably connected to the driven fixing disc through a driven spring. The belt is arranged in the V-shaped groove between the driven fixing disc and the driven movable disc. The driven fixing disc is connected to the driven shaft through an involute spline, and the driven shaft is in transmission connection with the output shaft through a gear set.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The present invention provides a clutch and speed change structure of a motorcycle engine. The driving wheel set is composed of a clutch assembly and a speed change assembly, and the clutch assembly is directly driven by the crankshaft. Since the rotation speed of the engine crankshaft is relatively high, the clutch response becomes faster. When the crankshaft rotates and the clutch rotation speed is not reached, the belt remains stationary, thus the service life of the belt can be extended.

[0017] 2. In the driving wheel set of the present invention, the traditional driving fixed disc structure is replaced by a clutch assembly, and the clutch structure is cancelled in the driven wheel set, thus greatly simplifying the original structure, making the engine structure more compact, lighter in weight, and simpler in combined assembly. The overall vehicle mass of the present invention can also be reduced, resulting in better safety, better passability, and better riding performance.

[0018] 3. The present invention concentrates most of the overall mass of the engine at the front end, making the structure more compact, and improving both safety and passability. At the same time, since the engine cooling fan is located at the front end, the clutch assembly can be better cooled, and the performance can be more stable.

[0019] 4. The structural design of the present invention is more suitable for large-displacement scooters. In large-displacement scooters, due to the increase in displacement and the increase in power and torque, the driven wheels of the traditional structure cannot bear the large-torque drive, and only the cost can be increased to replace the wet clutch structure. Since the rotation speed of the crankshaft of the present invention is relatively high, the centrifugal force will be greatly increased, and it can drive a larger torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a perspective view of the present invention;

[0021] Figure 2 is a perspective view of the transmission structure of the present invention;

[0022] Figure 3 is a perspective view of the crankshaft and the driving wheel set of the present invention;

[0023] Figure 4 is a cross-sectional view of the present invention;

[0024] Figure markings: 1. Crankshaft; 11. First bushing; 12. Gasket; 13. Thrust bearing; 14. Second bushing; 15. Locking nut; 2. Belt; 3. Clutch assembly; 31. Clutch plate; 32. Shoe; 33. Clutch cover; 34. Pin; 35. Clutch spring; 4. Speed change assembly; 41. Fixed plate; 42. Moving plate; 43. Puli bead; 51. Driven fixed plate; 52. Driven movable plate; 53. Driven spring; 54. Driven shaft; 55. Gear set; 56. Output shaft. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to specific embodiments of the present invention. Figures 1-4 :

[0026] A clutch transmission structure of a motorcycle engine includes a crankshaft 1, a driving wheel group and a driven wheel group. The driving wheel group is driven by the crankshaft 1, and the driving wheel group and the driven wheel group are connected by a belt 2. The crankshaft 1 is equipped with a clutch assembly 3 and a speed change assembly 4. The clutch assembly 3 and the speed change assembly 4 constitute the driving wheel group. The clutch assembly 3 includes a clutch disc 31, a shoe 32 and a clutch cover 33. The clutch disc 31 is keyed to the crankshaft 1. The clutch cover 33 is separated from the clutch disc 31 by the shoe 32 driven by centrifugal force. The speed change assembly 4 includes a fixed plate 41, a movable plate 42 and a bead 43. The fixed plate 41 is fixedly connected to the crankshaft 1, and the movable plate 42 is slidingly connected to the crankshaft 1. The bead 43 is arranged in the track of the movable plate 42 and drives the movable plate 42 to slide by centrifugal force. A V-shaped groove is formed between the clutch cover 33 and the movable plate 42, which is frictionally connected to the belt 2. The clutch cover 33 transmits the torque of the crankshaft 1 to drive the belt 2 to rotate. The movable plate 42 slides axially to change the pitch circle of the belt 2 to change the speed.

[0027] The working process of this embodiment is as follows: When the motorcycle starts, the rotational speed of the crankshaft 1 is relatively low. Although the clutch disc 31 rotates idly with the crankshaft 1, the shoe 32 is separated from the clutch cover 33 under the action of the clutch spring 35 due to insufficient centrifugal force, and the power cannot be transmitted to the belt 2. The movable disc 42 also remains in place because the weight 43 has no centrifugal force to push it, and the belt 2 is located at the minimum pitch diameter of the driving pulley set. When entering the idle stage, the rotational speed of the crankshaft 1 increases, and the shoe 32 begins to generate centrifugal force and is in semi-contact with the clutch cover 33. The belt 2 rotates at a low speed, and the motorcycle moves slightly forward. The weight 43 has a tendency to slide, but the movable disc 42 still does not move. When accelerating, the rotational speed exceeds the clutch critical value (the minimum engagement rotational speed of the shoe 32 with the clutch cover 33 under the action of centrifugal force is 2600 rpm). The shoe 32 fully adheres to the clutch cover 33, transmitting the torque of the crankshaft 1 to the belt 2. At the same time, the centrifugal force of the weight 43 increases, pushing the movable disc 42 to slide towards the clutch cover 33. The pitch diameter of the belt 2 increases, and at the same time, the pitch diameter of the driven pulley set decreases, realizing gear upshift and the rotational speed of the rear wheel increases. During the cruising stage, the rotational speed is stable, the movable disc 42 is fixed, and the transmission ratio remains unchanged, and the motorcycle maintains a constant speed. When decelerating, the rotational speed decreases, the shoe 32 is separated from the clutch cover 33 under the action of the centrifugal spring, the centrifugal force of the weight 43 decreases, the movable disc 42 slides in the reverse direction, the pitch diameter of the belt 2 decreases, and at the same time, the pitch diameter of the driven pulley set increases, realizing gear downshift. During the whole process, the cooling fan integrated on the crankshaft 1 operates continuously, directly flushing the clutch cover 33 and the movable disc 42, quickly taking away the heat generated during operation, ensuring the stable and efficient operation of the system, and the design driven by centrifugal force enables seamless linkage between clutch engagement and shifting actions, ensuring smooth starting.

[0028] The specific assembly structure of the driving pulley set of the present invention is:

[0029] The above-mentioned crankshaft 1 is installed with a first bushing 11 through a shaft shoulder. An involute spline for key connection with the clutch disc 31 is arranged on the crankshaft 1 outside the first bushing 11. The inner end face of the clutch disc 31 is in contact connection with the outer end face of the first bushing 11. The clutch disc 31 realizes axial positioning through the first bushing 11 and transmits torque through the involute spline.

[0030] Further, a gasket 12 and a thrust bearing 13 are sequentially sleeved on the crankshaft 1 outside the clutch disc 31. The two thrust washers of the thrust bearing 13 are respectively in contact connection with the gasket 12 and the clutch cover 33. When the shoe 32 on the clutch disc 31 is not sufficient to drive the clutch cover 33, the clutch cover 33 and the clutch disc 31 rotate relative to each other through the thrust bearing 13.

[0031] Further, a plurality of shoe blocks 32 are provided and distributed circumferentially. The inner side of the shoe block 32 is hinged to the clutch disc 31 through a pin shaft 34, and the outer side is covered with a friction material. A clutch spring 35 for driving the shoe block 32 to rotate inward is provided between the shoe block 32 and the pin shaft 34. When the rotational speed increases, the centrifugal force increases, the shoe block 32 is thrown outward, and at the same time the clutch spring 35 is stretched. The friction material on the outer side of the shoe block 32 drives the clutch cover 33 to rotate.

[0032] Further, a second bushing 14 is sleeved on the crankshaft 1 on the outer side of the clutch cover 33. The fixed disk 41 is in contact connection with the outer end face of the second bushing 14 to form an axial limiting structure. The moving disk 42 is slidably arranged on the second bushing 14. The second bushing 14 can simultaneously provide a circumferential sliding surface for the moving disk 42 and an axial positioning structure for the fixed disk 41.

[0033] Further, a locking nut 15 is screwed on the outer end of the crankshaft 1. After being locked, the locking nut 15 axially presses the first bushing 11, the clutch disc 31, the gasket 12, the thrust bearing 13, the clutch cover 33, the second bushing 14 and the fixed disk 41 in sequence.

[0034] The specific assembly structure of the driven wheel set in this embodiment is:

[0035] The above-mentioned driven wheel set includes a driven fixed disk 51 and a driven movable disk 52. The driven movable disk 52 is slidably connected to the driven fixed disk 51 through a driven spring 53. The belt 2 is arranged in the V-shaped groove between the driven fixed disk 51 and the driven movable disk 52. The driven fixed disk 51 is connected to the driven shaft 54 through an involute spline. The driven shaft 54 is in transmission connection with the output shaft through a gear set 55.

[0036] The driven wheel set cooperates with the driving wheel set during power transmission, realizes stepless speed change through the change of the tension of the belt 2, and at the same time transmits torque to the driven shaft 54 through an involute spline. After being driven by the gear set 55, the driven shaft 54 drives the output shaft 56 to rotate, and finally transmits power to the rear wheel efficiently. The driven movable disk 52 is connected to the driven fixed disk 51 through a driven spring 53. In the state of low tension of the belt 2, the driven spring 53 pushes the driven movable disk 52 towards the driven fixed disk 51, so that the belt 2 is located at the large-diameter outer side of the driven wheel set, forming a large transmission ratio, which is convenient for the vehicle to start smoothly. As the engine speed increases, since the total length of the belt 2 is fixed, this will cause a significant increase in the tension of the belt 2. Under the action of the increased tension of the belt 2, the driven movable disk 52 of the driven wheel set moves away from the driven fixed disk 51 against the resistance of the driven spring 53. While compressing the driven spring 53, the belt 2 gradually slides towards the small-diameter inner side of the driven wheel set. During this process, the transmission ratio of the driven wheel set continuously decreases, and the rotational speed of the rear wheel gradually increases, realizing vehicle acceleration. When the engine speed is stable, the driven wheel set also reaches a balanced state. The driven movable disk 52 maintains a stable position under the balance of the tension of the belt 2 and the elastic force of the driven spring 53. The position of the belt 2 on the driven wheel set no longer changes, and the transmission ratio is constant, so as to maintain the vehicle running at a stable speed. At this time, the power transmission efficiency is high, and the engine is in the economic speed range.

[0037] The above embodiments are only preferred embodiments of the present invention, and do not limit the protection scope of the present invention accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A clutch transmission structure for a motorcycle engine, comprising a crankshaft (1), a driving wheel set and a driven wheel set, wherein the driving wheel set is driven by the crankshaft (1), and the driving wheel set and the driven wheel set are connected by a belt (2), characterized in that: A clutch assembly (3) and a speed change assembly (4) are sleeved on the crankshaft (1). The clutch assembly (3) and the speed change assembly (4) form the driving pulley set. The clutch assembly (3) includes a clutch disc (31), shoe blocks (32) and a clutch cover (33). The clutch disc (31) is key-connected to the crankshaft (1). The clutch cover (33) is in clutch connection with the clutch disc (31) through the shoe blocks (32) driven by centrifugal force. The speed change assembly (4) includes a fixed disc (41), a movable disc (42) and Puli beads (43). The fixed disc (3) is fixedly connected to the crankshaft (1). The movable disc (42) is slidably connected to the crankshaft (1). The Puli beads (43) are arranged in the track of the movable disc (42) and drive the movable disc (42) to slide through centrifugal force. A V-shaped groove for friction connection with the belt (2) is formed between the clutch cover (33) and the movable disc (42). The clutch cover (33) transmits the torque of the crankshaft (1) to drive the belt (2) to rotate. The movable disc (42) slides axially to change the pitch circle of the belt (2) for speed change.

2. The clutch shifting structure of a motorcycle engine according to claim 1, wherein, A first bushing (11) is installed on the crankshaft (1) through a shaft shoulder. An involute spline for key-connection with the clutch disc (31) is arranged on the crankshaft (1) outside the first bushing (11). The inner end face of the clutch disc (31) is in contact connection with the outer end face of the first bushing (11).

3. A clutch shifting structure of a motorcycle engine according to claim 2, characterized in that, A gasket (12) and a thrust bearing (13) are sequentially sleeved on the crankshaft (1) outside the clutch disc (31). The two thrust washers of the thrust bearing (13) are respectively in contact connection with the gasket (12) and the clutch cover (33).

4. A clutch shifting structure for a motorcycle engine according to claim 3, characterized in that, A plurality of shoe blocks (32) are arranged and distributed circumferentially. The inner side of the shoe blocks (32) is hinged to the clutch disc (31) through a pin shaft (34), and the outer side is covered with friction material. A clutch spring (35) for driving the shoe blocks (32) to rotate inwards is arranged between the shoe blocks (32) and the pin shaft (34).

5. The clutch shifting structure of a motorcycle engine according to claim 3, characterized in that, A second bushing (14) is sleeved on the crankshaft (1) outside the clutch cover (33). The fixed disc (41) is in contact connection with the outer end face of the second bushing (14) to form an axial limiting structure. The movable disc (42) is slidably arranged on the second bushing (14).

6. The clutch and speed change structure of a motorcycle engine according to claim 5, characterized in that, A locking nut (15) is screwed on the outer end of the crankshaft (1). After being locked, the locking nut (15) axially presses the first bushing (11), the clutch disc (31), the gasket (12), the thrust bearing (13), the clutch cover (33), the second bushing (14) and the fixed disc (41) in sequence.

7. A clutch shifting structure for a motorcycle engine according to claim 1, characterized in that, The driven pulley set includes a driven fixed disc (51) and a driven movable disc (52). The driven movable disc (52) is slidably connected to the driven fixed disc (51) through a driven spring (53). The belt (2) is arranged in the V-shaped groove between the driven fixed disc (51) and the driven movable disc (52). The driven fixed disc (51) is connected to the driven shaft (54) through an involute spline. The driven shaft (54) is in transmission connection with the output shaft (56) through a gear set (55).

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