Power steering rack and pinion
The power rack and pinion steering system has a rotary control valve that directs hydraulic fluid from the hydraulic pump to one side or the other of the rack plunger. One-piece rail plunger is connected to the rail. The rack plunger converts hydraulic pressure into a linear force that moves the rack left or right. Further, this force is transmitted through the tie rods to the steering knuckles, which turn the wheels.
If the power steering is not functioning, the rack and pinion steering mechanism is mechanically controlled, however, in this case, more steering effort will be required. The rotation of the steering wheel is transmitted to the gear. The rotational motion of the pinion is transmitted to the pinion worm, the threads of which mesh with the teeth of the rack, thus causing the rack to move linearly.
A vane-type hydraulic pump provides pressure for both steering systems.
Power steering providing variable speed-dependent power steering
In a power steering system that provides variable speed-dependent power steering, (SSPS) changes the effort of the driver, which is required to turn the steering wheel when the speed of the car changes. At low speeds, the system provides maximum power for easier turning and parking maneuvers. At high speed, the steering gain is reduced to provide firmer control and improved directional stability. The SSPS performs this task by regulating the current (-3~3A), supplied to the winding of the electromagnet included in the equipment of the electric power steering mechanism, as the vehicle speed increases. When the vehicle is stationary, the SSPS provides maximum steering assistance to the steering. As the speed of the vehicle increases, the steering gain of the steering gear decreases.
Controller
The SSPS controller processes vehicle speed information from the ABS controller to the solenoid coil located on the electric power steering assembly.
Power steering rack and pinion
Except for the difference in valve processing, the design of the rack and pinion steering gear with SSPS is similar to the design of the steering gear without SSPS. The rotation of the steering wheel is transmitted to the gear through the intermediate shaft. The pinion moves the rack left or right by meshing the teeth of the gear and rack. This force is then transmitted through the tie rods and steering knuckles to the steered wheels.
The power rack and pinion steering system has a rotary control valve that directs hydraulic fluid from the hydraulic pump to one side or the other of the rack plunger. A plunger connected to the rack converts hydraulic pressure into moving the rack to the left or right. The rotary control valve adjusts the gain in response to driver torque.
If the hydraulic booster does not function, the mechanical control works. However, in this case, more significant steering effort will be required.
Power Steering Pump
Standard vane-type hydraulic pump providing hydraulic pressure to the system.
System operation
The system starts with an input signal from the vehicle speed sensor through the ABS controller to the SSPS controller. The SSPS controller sends a signal to the SSPS actuator to change the level of reactive force produced by the solenoid winding.
Circuit operation
The SSPS system uses the input signals from the ABS controller to the SSPS controller, setting the required amount of force applied from the electric power steering mechanism.
The SSPS controller continuously compares the amount of current flowing through the SSPS drive with its calculated value. The SSPS actuator has an electromagnet winding that can control the reactive force applied to the steering torsion bar. The SSPS controller can change the amount of current flowing through the SSPS drive by changing the output duty cycle.
The SSPS controller can detect faults in itself, the SSPS drive, or the circuits of such components. The detection of any malfunction causes the steering gain to remain at its highest level at all times as the needle assumes its normally extended position at all speeds.
When the system is operating normally, steering gain is reduced as speed increases, providing the driver with a better sense of the road and improved directional stability.