Dual-planetary-gear transmission for electric vehicle, and control method thereof

Abstract

The invention relates to a dual-planetary-gear transmission for an electric vehicle. The dual-planetary-gear transmission comprises a driving motor, a differential mechanism, a first brake, a second brake, a first planetary gear set and a second planetary gear set; the first planetary gear set comprises a first sun gear, a first planetary frame and a first gear ring; the second planetary gear setcomprises a second sun gear, a second planetary frame and a second gear ring; and an output shaft of the driving motor is connected with the first sun gear and the second gear ring, the first gear ring is connected with the first brake, the second sun gear is connected with the second brake, the first planetary frame and the second planetary frame are connected to form a whole, the first planetaryframe is provided with an output bracket, and the output bracket is connected with an input shaft of the differential mechanism. Compared with the prior art, according to the dual-planetary-gear transmission, power interruption in the gear shifting process can be avoided, the control complexity and the requirements for performance of the driving motor are low, and practicality is high.

Description

technical field [0001] The invention relates to the technical field of electric vehicle transmission, in particular to a dual planetary gear transmission and a control method for electric vehicles. Background technique [0002] At present, most of the pure electric vehicles on the market use a single-stage reduction mechanism without gears, and the motor completes the task of shifting. Although its structure is simple and the cost is low, it cannot take into account the power and economy of pure electric vehicles. According to the motor Characteristic curve, gearless deceleration is difficult to keep the drive motor working in the high-efficiency range, which reduces the efficiency of the electric drive assembly system. Especially in the low-load conditions of starting and maximum speed, the motor is in the low-efficiency zone, which seriously affects the life and endurance of the battery. [0003] In the patent with the publication number CN207333612U, a two-speed electric...

AI Technical Summary

Problems solved by technology

[0002] At present, most of the pure electric vehicles on the market use a single-stage reduction mechanism without gears, and the motor completes the task of shifting. Although its structure is simple and the cost is low, it cannot take into account the power and economy of pure electric vehicles. According to the motor Characteristic curve, gearless deceleration is difficult to keep the drive motor working in the high-efficiency range, which reduces the efficiency of the electric drive assembly system

Especially in the low-load conditions of starting and maximum speed, the motor is in the low-efficiency zone, which seriously affects the life and endurance of the battery

[0003] In the patent with the publication number CN207333612U, a two-speed electric drive system for pure electric vehicles is disclosed. In this invention, there are two-speed output gears on the intermediate shaft assembly, which are arranged on both sides of the synchronizer and vacantly sleeved on the input shaft. The shifting function is realized by the electric shifting unit and the synchronizer, and the structure is simple, but the parallel shaft transmission design needs to switch gears during the shifting process, and there is power interruption, which reduces the driving quality of the vehicle

[0004] In the patent with the publication number CN207349420U, a new type of horizontal two-speed pure electric wet clutch automatic transmission is disclosed. The wet dual clutch transmission is a two-shaft structure. The control hydraulic system and the wet clutch realize the switching of two gears, but the nonlinear characteristics of the hydraulic servo system make it more difficult to accurately control the clutch pressure, and the smoothness of shifting is affected, and the processing technology is relatively complicated and the cost is high

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