Pacific Automotive Network MG 5cvt uses steel belts. MG 5 is a compact coupe of MG. The length, width and height of this car are 4675 mm, 1842 mm, 1473 mm respectively, and the wheelbase is 2680 mm. It is a four-door, five-seater sedan.
CVT has two power transmission methods, one is a steel belt and the other is a chain. Generally speaking, steel belts are usually suitable for engines with small torque, while chains are usually used for engines with high torque. , judging from the actual performance, there is no doubt that the chain is relatively durable and durable, and has a longer service life. The performance-oriented CVT gearboxes in the world all use chain solutions, such as the early Audi Multitronic CVT, the current Subaru Lineartronic CVT, Nissan CVT8HT, etc.
The structural difference between chains and steel belts. CVT steel belts are supported by two embedded steel belts. Hundreds of steel plates are stuck on the metal belts. Steel belts with this push-plate structure , the power can only be transmitted by "push", and the hardness of the material between the push pieces is used to form thrust. The push pieces deform less under the action of external force. During power transmission, the active cone wheel tightly presses the entire side of the steel belt, forming Due to static friction, the driving cone wheel pushes the driven cone wheel to rotate through the steel belt.
The structure of the CVT chain is obviously different from that of the steel belt. The chain does not directly contact the cone wheel, but achieves torque transmission by pressing the rocker pin in the middle. The structure of the chain consists of two It consists of bundles of ring-shaped steel sheets and pull tabs. Each bundle of steel strips is composed of 12 high-tensile thin steel sheets. Patented T702 high-strength steel is inserted into each group of steel sheets to form a rocker pin for connection. The tensile strength is as high as 2000mpa. This structure of the chain can only use the "pull" method for power transmission. The active cone wheel presses the "rocker arm pin" of the chain to form static friction and drive the chain to transmit torque.
The cost of the chain is more than that of the steel belt. Currently, only Bosch can provide the CVT that can be mass-produced in the world (Honda can produce it). In the early days, the chain was only provided by Schaeffler, but now Bosch can also provide it. However, overall, since the shipment volume of the chain is really small, the amortized cost is also relatively high.
The most critical thing is that from a structural point of view, the tensile steel sheet used in the chain can withstand a relatively large torque. In addition, because the cone wheel does not directly contact the chain, but only contacts the rocker pin , the actual contact area is not large, so the requirements for materials are higher. The cost is naturally relatively higher. The cost is high, and naturally it is rarely used. Especially for the stingy Japanese who control costs to the extreme, it is even more impossible to use chain transmission.
The chain can withstand greater torque than the steel belt. Since the cone wheel of the CVT is an inclined surface, when the steel belt uses thrust to transmit force, the cone wheel extrusion will form an outward squeezing thrust and a large torque. The output will tend to slip, and once the cone wheel releases pressure, the entire CVT steel belt will spread out instantly.
Relatively speaking, the chain uses a tension transmission method. When the cone wheel is pressed, an inward pulling force will be generated. As long as the chain material can withstand it, it will form a trend of getting tighter and tighter, and there is a chance of slipping. Relatively smaller, it can withstand greater torque.
The transmission efficiency of the chain is higher. Compared with the steel belt transmission, once the steel belt enters the cone wheel range and comes into contact with the cone wheel, it must be ensured that all steel pieces are pressed against the cone wheel to generate enough energy. static friction.
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