Various working conditions.
1 Problems Currently, the scooter usually adopts a belt type continuously variable transmission, and its structure (see) is mainly composed of a driving pulley, a driven pulley, a transmission belt and a clutch.
The driving pulley is mounted on the crankshaft of the engine, and is composed of an active fixed wheel 1, an active moving wheel 3, a centrifugal roller 4 and a chassis 6.
The driven pulley is composed of a driven fixed wheel 11, a driven moving wheel 13, a pressing spring 12, and the like. The clutch chassis 9 is interlocked with the driven pulley and is mounted with a centrifugal block 8. When the driven wheel speed reaches a predetermined value, the centrifugal block 8 moves radially against the spring pulling force, combines with the clutch drum 7, and drives the wheel to rotate. The faster the driven wheel rotates, the greater the pressing force of the centrifugal block and the greater the torque that the clutch can transmit.
Under the joint action, the active moving wheel 3 is close to the active fixed wheel 1 to cause the working diameter of the driving pulley to become larger. Since the length of the belt is fixed, this forces the driven moving wheel 13 to be separated from the driven fixed wheel 11, so that the working diameter of the driven pulley becomes smaller, and the ratio of the driving speed of the driving pulley to the rotational speed of the driven pulley is reduced, that is, The speed of the moving pulley increases and the torque decreases. When the crankshaft speed decreases, the change is opposite to the above. It can be seen that the transmission ratio of the transmission is controlled by the engine speed and continuously changes steplessly. Therefore, it only adapts to high-speed, low-resistance conditions, and does not adapt to low-speed heavy-duty conditions such as start-up, acceleration, and hill climbing. In starting, accelerating and climbing, the vehicle needs more power and torque. In actual operation, it is necessary to increase the throttle and increase the engine speed. However, the engine speed increases, the gear ratio decreases, and the driven pulley The torque is reduced, and because there is not enough torque, the actual speed of the vehicle is not synchronized with the engine speed, causing the drive belt and clutch to slip. At the same time, since the clutch is mounted on the driven pulley, the torque that can be transmitted decreases as the driven wheel speed decreases, and it does not adapt to the low speed and large resistance conditions. Therefore, the scooter using such a transmission generally has a phenomenon of slow start and acceleration, difficulty in climbing, belt and clutch slip, heat generation, short life, large engine power loss, and high fuel consumption.
2 Solution In view of the above situation, a speed control gearless input shaft is designed through multiple experiments. n. The driven fixed wheel 12 is pressed by the spring 13 to move the wheel drive. It is controlled by the method of changing the speed ratio to adapt the gear ratio of the main and the slave pulley to the crankshaft speed. When the crankshaft speed increases, the centrifugal roller 4 in the driving pulley moves radially under the action of the centrifugal force, and the motorcycle 6 starts and accelerates, climbs, and drives at the steering wheel of the chassis 6 and the active moving wheel 3. Working conditions, thereby reducing fuel consumption, improving handling performance, and extending the life of the belt and clutch.
3-speed control continuously variable transmission construction The transmission (see) consists of a primary pulley, a driven pulley, a clutch and a transmission belt. Among them, the driving pulley and the clutch are mounted on the crankshaft. The driving pulley is composed of an active fixed wheel 1 (and a clutch drum), an active moving wheel 8 active spring 9, a retaining ring 10, a spring retaining ring 11, a bearing and the like. The active fixed wheel 1 is sleeved on the crankshaft through two sets of bearings; the active moving wheel 8 is mounted on the spline sleeve on the side of the active fixed wheel 1, and rotates synchronously with the active fixed wheel 1, and can approach or leave the active fixed wheel in the axial direction. . The function of the active spring 9 is to press the active moving wheel 8 to be close to the active fixed wheel L. The clutch chassis 4 is fixedly mounted on the crankshaft by means of a key, and three centrifugal blocks are mounted thereon. The centrifugal block 2 is radially tensioned by a tension spring. . When the engine is running at an idle speed, the centrifugal block 2 is not coupled to the active fixed wheel 1, and the primary pulley does not rotate. When the engine speed rises to a certain value, the centrifugal block 2 overcomes the spring pulling force and combines with the active fixed wheel 1 to drive the driving pulley to rotate. The higher the engine speed, the greater the clutch engagement force and the greater the torque that can be transmitted. The driven pulley is composed of a driven fixed wheel 13 driven moving wheel 14, a pressure plate 15 eccentric block 16, a driven spring 17, and a spring retaining ring 11. The driven fixed wheel 13 is driven by the spline on the rear wheel wheel reducer input shaft, and the driven moving wheel 14 is equipped with 6 eccentric blocks 16 between the driven moving wheel 14 and the pressure plate 15. The driven spring 17 is arranged to enable the driven moving wheel 14 to approach the driven fixed wheel 13. When the driven wheel speed increases, the six eccentric blocks 16 can be radially opened, since the rotating shaft of the eccentric block 16 is eccentric, After the splitting, the force of the driven spring 17 can be overcome, so that the driven moving wheel 14 is close to the pressing plate 15 away from the driven fixed wheel 13. The working principle is that the active spring 9 in the driving pulley has a small elastic force, but Press the pulley to make the belt generate enough friction.
The spring force of the driven spring 17 in the driven pulley is larger than that of the active spring, so that when the stationary or driven pulley rotates at a low speed, the pressing force of the driven moving wheel 14 on the belt is stronger than that of the active moving wheel 8. Big. At this time, the working diameter of the driven pulley is the largest, and the working diameter of the driving pulley is the smallest. The ratio of the driving speed of the driving pulley to the driven pulley is the largest, and the driven pulley can obtain a large torque and a small rotating speed. Adapt to the conditions of starting, accelerating and climbing the motorcycle. When the vehicle speed rises to a certain value (1015km / h), the eccentric block 16 on the driven pulley overcomes the force of the driven spring 17 to radially open, so that the driven moving wheel 14 moves away from the driven fixed wheel 13 The working diameter of the pulley is gradually reduced, the working diameter of the driving pulley is gradually increased, and the gear ratio is reduced. When the vehicle speed continues to rise to another value (2530km/h), the driven pulley has the smallest working diameter and the smallest gear ratio. The driven pulley can obtain larger speed and minimum torque to adapt to high speed on a good road surface. Low resistance driving conditions. It can be seen that the speed ratio of the transmission is controlled by the speed of the driven pulley (the speed of the driven wheel is proportional to the speed of the vehicle), and it can continuously change continuously within a certain range, so it is called a speed-controlled continuously variable transmission.
5 Design points According to the engine power and the reduction ratio of the rear wheel reducer of the motorcycle, the gear ratio range of the transmission is reasonably selected, generally in the range of 0.83, so that the vehicle performance matches the engine characteristic curve.
The maximum and minimum gear ratios of the transmission are related to the size and shape of the main and slave pulleys, the moving distance of the moving wheels, the shape of the transmission belt, etc., and should be reasonably selected through calculation.
The transmission's speed from the maximum gear ratio to the start of the reduced speed (10 / h) and the speed of the minimum gear ratio (2530km / h) are two key data, which are related to the matching of engine, transmission and vehicle performance. . It is related to the elastic characteristics of the active spring and the driven spring, the mass and shape of the eccentric mass, and should be rationally designed through calculation and repeated experiments.
Compared with the original technology, this design retains the advantages of smooth, continuous and simple operation of the original technology. In terms of power performance, the transmission is similar to a gear-driven transmission, which can adapt to various driving conditions of the vehicle, thereby reducing the belt. And the clutch slips and heats, reducing engine power loss and reducing fuel consumption. The clutch is placed on the crankshaft, which is beneficial to low speed and large torque working conditions; the clutch drum and the active fixed wheel are integrated into one body with simple structure and reliable performance; the fixed and moving wheels on the main and driven pulleys are all splined. Connection, the fixed wheel and the moving wheel have no relative rotation, and the two sides of the belt are evenly stressed, which is beneficial to power transmission and reduce sliding. The transmission can be used without the need to change the main structural form of the original motorcycle transmission casing, and the clutch block and the transmission belt can be borrowed, which makes the technical transformation easier to implement.
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