Hydraulic active steering system of big bus and control method

Abstract

The invention discloses a hydraulic active steering system of a big bus and a control method. The hydraulic active steering system comprises a mechanical steering module, a hydraulic booster module, a hydraulic active steering module, a main control module and a sensor module; the hydraulic booster module provides steering boost for the system according to booster characteristics, and good steering portability is achieved; and the hydraulic active steering module provides compensation displacement for the steering system according to a compensation control strategy, and active steering of the system is achieved. When a vehicle is in different driving conditions, a control strategy of the hydraulic booster module and the hydraulic active steering module is determined by an electronic control unit according to information collected by the sensor module, and the stability and the safety of the big bus during running are improved.

Description

technical field [0001] The invention belongs to the technical field of automobile power steering system control, and specifically refers to a hydraulic active steering system and a control method of a bus. Background technique [0002] The steering torque required by passenger cars is large, and the power requirements for steering assistance are relatively high. At present, passenger cars generally use hydraulic power steering systems. Compared with the traditional mechanical hydraulic power assist, the electrohydraulic power steering system has good steering performance and handling stability at the same time. [0003] The traditional hydraulic power assist system uses the power output by the engine to drive the hydraulic power assist system, which solves the problem of laborious steering. However, due to the fixed structure of the steering valve, the assist characteristics of the hydraulic system cannot be changed, that is, the magnitude of the assist remains constant whe...

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Problems solved by technology

[0005] However, the electro-hydraulic power steering system widely used in buses currently has a constant transmission ratio, that is, the ratio of the steering wheel angle increment to the front wheel angle increment is constant, which cannot meet the requirements of an ideal steering system that is flexible at low speeds and stable at high speeds.

[0006] In China, Zhao Wanzhong and others proposed an electronically controlled hydraulic power steering system with variable transmission ratio function, which can improve the steering stability of the car while allowing the driver to obtain a better steering feel, but this system is suitable for rack-and-pinion steering device, cannot be used on the recirculating ball steering device of the bus

Chi Yongbin et al. proposed a dual-shrink cylinder hydraulic power-assisted active steering gear to control the steering angle displacement and torque in coordination, but the structure of the nested power cylinder based on the rack and pinion is complex, and the power assistance provided is difficult to meet the requirements of the bus.

[0007] Abroad, the German BMW company has pioneered the AFS active steering system in the world. This system adds a set of double planetary gear mechanism to the steering column to superimpose an additional steering angle to the steering wheel, which meets the needs of variable transmission ratio and solves the problem of steering system. The contradiction between flexibility and lightness at low speeds and directional stability at high speeds enables the vehicle to provide ideal steering characteristics at any speed, but BMW uses electric power assist, and the steering power is limited, which is not suitable for heavy vehicles

Mercedes-Benz has developed a "direct steering system", which uses a rack with a dense middle pitch and loose ends at both ends to realize a mechanically variable transmission ratio. Variety

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