Electro-hydraulic power steering system for battery electric buses

Abstract

The invention discloses an electro-hydraulic power steering system for battery electric buses. The electro-hydraulic power steering system which is effectively energy-saving comprises a steering wheel, a steering oil cylinder, a flow control valve and overflow valve assembly, a steering hydraulic pump, a steering drive three-phase asynchronous motor, a converter, a hybrid power supply, a steering drive motor speed sensor, a bus drive motor speed sensor, a front axle load sensor, a speed sensor and a recirculating ball integrated power steering gear. The recirculating ball integrated power steering gear is composed of a steering screw, a steering control valve, a steering power cylinder, a steering nut and a steering gear sector. The electro-hydraulic power steering system has the advantages that control methods of multiple driving conditions such as front axle load are changed, steering drive motor speed is controlled, steering energy saving is improved, and portability and good touch are balanced with stability and fast response.

Description

technical field [0001] The invention relates to a power steering system of a pure electric vehicle, in particular to an electrohydraulic power steering system of a pure electric bus. Background technique [0002] At present, the power steering system used on pure electric buses is mainly an electrohydraulic power steering system driven by a three-phase asynchronous motor. There are mainly the following problems: the frequency divider can adjust the frequency and voltage of the composite power supply and transmit the frequency-regulated and voltage-regulated AC power to the steering drive motor, but the frequency divider used in the steering drive of the existing pure electric bus lacks the real-time control function. The rotation speed of the steering drive motor cannot be adjusted according to the front axle load, vehicle driving conditions and vehicle speed, so that the output oil flow and pressure of the steering hydraulic pump cannot be controlled. If the oil flow is de...

AI Technical Summary

Problems solved by technology

[0002] At present, the power steering system used on pure electric buses is mainly an electrohydraulic power steering system driven by a three-phase asynchronous motor. There are mainly the following problems: the frequency divider can adjust the frequency and voltage of the composite power supply and transmit the frequency-regulated and voltage-regulated AC power to the steering drive motor, but the frequency divider used in the steering drive of the existing pure electric bus lacks the real-time control function. The rotation speed of the steering drive motor cannot be adjusted according to the front axle load, vehicle driving conditions and vehicle speed, so that the output oil flow and pressure of the steering hydraulic pump cannot be controlled

If the oil flow is designed to be large, low-speed steering is light but high-speed feel is poor, and the oil flow is small, and vice versa, so there is a contradiction between steering lightness and feel. If the oil flow is designed to be large, the quick response performance is good but the stability is poor. The opposite is true when the oil flow rate is small, so there is a contradiction between fast response and stability

The maximum speed of the steering drive motor required by pure electric buses changes with the change of the front axle load, but the current method of controlling the steering of the electro-hydraulic power steering system does not fully consider this influencing factor, making the steering energy-saving performance poor

After searching the relevant patent documents, the U.S. Patent Office No. 7303044B2 proposes to use the motor current change rate signal instead of the steering wheel angular velocity change rate signal input controller, which reduces the installation of the steering wheel angular velocity sensor and reduces the cost of the steering system. This does nothing to improve system steering performance and reduce steering energy consumption

Chinese invention patent, the publication number is CN 101239625A, and the patent document titled "a motor-driven bus hydraulic steering system and its method for controlling steering" proposes a method for controlling the motor speed by using a multi-working mode control method. Although this system structure and control method can improve the steering performance and energy-saving performance of the steering system, it does not consider the influence of the change of the front axle load on the required speed of the steering drive motor of the pure electric bus under various driving conditions and vehicle speeds. , thereby limiting the further improvement of the steering energy-saving performance

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