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1 active steering system
Introduction:
Since the invention of the automobile, the steering gear drive are usually fixed. In other words, whether it is put on hold in the narrow streets of downtown or the Mercedes-Benz on the highway, the steering wheel and front-wheel steering angle than the always static. It is therefore engineers face a difficult choice: if direct steering, the driver is too sharp when you do not need turn the steering wheel sharply, but at high speeds, the steering wheel subtle movements will affect the driving stability; Conversely, the more indirect steering system, the stability of the vehicle traveling on the highway, the higher, but must sacrifice handling when cornering. Therefore, the conventional steering system must make a trade-off between security and comfort. BMW engineers through several years of research and development efforts, developed a revolutionary active steering system, and the first appearance in the new BMW 5 Series. The system ensures that the vehicle can provide ideal steering control at any speed, and taking into account the maximum driving pleasure, agility and safety, this is the first time in automotive history.
Principle:
When the driver turned the steering wheel angle, the steering wheel that will necessarily a fixed deflection angle. The driver during cornering, the road surface curvature changes according to the need, the vehicle speed changes and other factors, continue to adjust the angle of the steering wheel by turning the steering wheel, the driver wishes to maintain the achieved turning circle. Conventional steering system has its own advantages, steering reliable, low failure rate, but there are certain drawbacks in that if the steering gear ratio is large, the vehicle turns at low speeds relatively lightweight, but at high speed the steering state it is far too sensitive steering stability deteriorates. Conversely, if the steering gear is relatively small, the vehicle turns at high speed will become stable, but at low speeds, the steering would be more difficult.
The greatest feature of the active steering system is based on driving conditions, automatic adjustment of vehicle steering gear ratio, thereby increasingOr reducing the steering angle of the front wheels. At low speed, the motor acting in concert with the driver turns the steering wheel in the direction of the steering gear ratio is increased, the driver can reduce the need for the steering force. At high speed, running direction of the motor rotation direction opposite to the driver’s steering wheel, which reduces the steering angle of the front wheels, the steering gear ratio decreases, the steering stability is improved.
In addition to a more comfortable, more flexible than, Active Steering Another very important point is more secure, which is mainly reflected in a sudden reversal in the high-speed driving. For example, when a sudden lane change to surpass another car at high speed on the highway and then when back lane, or high speed suddenly found in front of obstacles need a sharp turn, it is prone to understeer or oversteer, the vehicle will deviate from their own predetermined direction, you may lose control. In this case, the active steering system from a steering will judge the situation after the start of steering, electronic control of the mechanical governor automatically corrected steering angle, yaw reduce the interference situation.