Motor-driven power-assisted steering system with duly-variable transmission ratio and control method thereof

Abstract

The invention discloses a motor-driven power-assisted steering system with a duly-variable transmission ratio and a control method thereof, belonging to a motor-driven power-assisted steering system. The system comprises a steering wheel (1), a torque sensor (2), a steering motor (3), a planet gear (4), a sun gear (5), a gear ring (6), a steering tubular column (38), a power-assisted motor (7), a retarding mechanism (8), a rack (9), a steering rocker arm (10), a front wheel (11), an electronic control unit ECU (12), an advanced electronic control module ECUa (27), a vehicle-mounted satellite navigator (28), a vehicle-mounted foresight road condition instrument (29) and a self-adaption memory electronic control module ECUb (30). Because a planetary gear mechanism, a steering synchronizing clutch and a steering motor are added between the torque sensor and the gear rack, the motor-driven power-assisted steering system can realize the functions of steering mode selection, duly self-adaption variable transmission ratio control and active steering intervention on the basis of finishing the original motor-driven power-assisted steering; the steering stability and the travelling safety of the automobile can be improved; and the safety and the flexibility of the automobile can be perfectly combined.

Description

technical field [0001] The invention relates to an electric power steering system with timely variable transmission ratio and a control method thereof, belonging to the electric power steering system. Background technique [0002] The electric power steering system is a new and promising power steering system. It completely cancels the hydraulic components. The whole system is composed of a steering wheel torque sensor, a vehicle speed sensor, a controller, a power assist motor and its deceleration mechanism. The basic principle is that the controller receives the steering wheel torque signal and the vehicle speed signal, and after judgment and processing, outputs a control signal according to the pre-determined power boost characteristics, and controls the motor to output power boost torque. [0003] At present, the electric power steering system at home and abroad adopts a fixed transmission ratio, but the fixed transmission ratio is not conducive to changing the performan...

AI Technical Summary

Problems solved by technology

[0003] At present, the electric power steering system at home and abroad adopts a fixed transmission ratio, but the fixed transmission ratio is not conducive to changing the performance of the steering system: the steering wheel tends to sink at low speeds; At high speeds, dangerous conditions such as oversteer are prone to occur, and there are hidden dangers in the handling stability of the car.

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