The “heart” of a pure electric vehicle is the motor, and as a key transmission component, the structural selection of the reducer has a profound impact on vehicle performance. In theory, a two-speed reducer can bring significant advantages:
1. Stronger power: The low-speed gear with a large speed ratio brings more rapid acceleration and climbing ability; the high-speed gear with a small speed ratio can reach a higher top speed.
2. Higher efficiency: Let the motor run in the high-efficiency range more time, improving the endurance potential.
3. Cost potential: It may allow the use of smaller, lower-speed (and therefore cheaper) motors, as well as lower-cost bearings, gears and other components.
Since the two-speed advantage is obvious – power, efficiency, and potential cost are all superior – why do most electric vehicles on the road today still stick to the simple single-speed reducer? Would you rather increase the motor speed to even more than 25,000 rpm?
The early attempt of Tesla Model S (the two-speed transmission plan that was ultimately not mass-produced) seemed like an industry “turning point”. Does its “failure” imply an insurmountable obstacle?
The question is for all industry experts, technical experts and enthusiasts: What are the key difficulties that hinder the large-scale production and application of two-speed reducers?
Is it the following reasons? Or do you have more unique insights?
1. Difficulties in shifting mechanisms and strategies? How to achieve smooth, fast and reliable shifting at high motor speeds? Is the development of electronic shifting logic extremely complicated?
2. NVH (noise, vibration and harshness) curse? Will adding a shifting mechanism inevitably bring annoying noise, impact or vibration, destroying the quietness advantage of electric vehicles?
3. Cost overtaking risk? Although there may be room for cost reduction of components such as motors, will the complex transmission body development, the newly added shifting actuators, and rigorous testing and verification significantly increase the total system cost and offset the theoretical advantages?
4. Reliability and durability challenges? Do the extra moving parts mean higher failure rates and warranty costs?
5. Compromise between volume and weight? Will the two-speed structure be too bloated, occupying valuable chassis space and increasing vehicle weight?
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