How does the automobile steering hydraulic system work?

by:DEFUS     2020-05-26
The automobile steering hydraulic system is an early power steering assist system. The hydraulic power steering system is composed of hydraulic pumps, oil pipes, pressure and flow control valve bodies, V-shaped transmission belts, oil storage tanks and other components. When the vehicle is turning, due to the intervention of the assist system, the heavy steering problem is solved, and part of the driver's labor force is liberated. However, this traditional hydraulic power steering system has one of the biggest disadvantages, that is, when the car is guaranteed to be light and flexible when parking or turning at a low speed, then the vehicle will have a feeling of flutter and instability during high-speed driving. If it is to ensure the stability of the vehicle in the direction of high-speed driving, and the vehicle has to stop or turn around at a low speed, it will feel too heavy when turning in the direction. Later, an electronic control system ~ an electronically controlled hydraulic power steering system was added to the traditional power-assisted hydraulic steering system. Electronically controlled hydraulic power steering system: mainly composed of electronic control system, steering gear box, oil pump and diverter valve. A steering oil pump is installed on the engine, which is driven by the crankshaft through a belt and outputs hydraulic oil to the outside. The transfer oil tank is connected with the steering oil pump and the steering control valve through the oil pipe. The steering control valve can change the oil circuit. The steering gear and the cylinder rash form two working chambers, which are connected through the oil passage and the steering control valve. The ECU electronic control unit acquires different speed signals of the vehicle from the wheel speed sensor, recognizes the conditions of the vehicle under various working conditions, and performs linear control of the solenoid valve coil current in a timely manner. When the speed is low or the steering angle is large: When the power of the solenoid coil is large, the excess hydraulic oil diverted by the diverter valve flows back to the oil storage tank through the solenoid valve, and the oil pressure on the plunger is small. When the steering wheel rotates, the torsion bar Larger torque variables may be generated. The piston driving the power cylinder moves to the left or right, and the auxiliary force increases, thereby increasing the steering force to adapt to the low-speed or large steering angle of the vehicle. When driving at high speed: The steering control valve communicates the working hydraulic oil from the steering oil pump with the oil tank. The steering oil pump is in the unloaded state, and the power steering no longer plays a role in boosting, which enhances the driver's feel and the road feel when turning.
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