Hybrid power steering system

摘要

In a hybrid power steering system, two steering assisters for supporting a steering force when the driver operates the steering wheel. The steering supporting force can be divisionally used according to the increase of speed and weight of a vehicle, thereby reducing the load applied to any of the steering assisters such that operating noise can be reduced and the endurance can be increased. Further, a motor of a lower power specification may be used even in the case of a truck or a bus that requires a relatively high steering force as compared to a passenger vehicle. Accordingly, production costs can be reduced and a sufficient steering supporting force can be obtained, thereby improving the driver's convenience, and enhancing fuel efficiency while increasing energy efficiency. Further, the steering can be safely maintained even when one of the steering assisters is not operating normally while the vehicle is being driven.

主权项

1. A hybrid power steering system comprising:
a first steering assister configured to rotate a steering shaft in a forward or reverse direction using a driving force of a first motor to support a steering force; a second steering assister configured to rotate a sector shaft of a gear box in a forward or reverse direction using a hydraulic pressure of a hydraulic oil of an oil pump driven by a second motor to support the steering force; a torque sensor configured to sense a rotational torque of the steering shaft; a speed sensor configured to sense a vehicle speed; and an electronic control unit configured to send target electric current value control signals to the first motor and the second motor according to input signals input from the torque sensor and the speed sensor, respectively, wherein the first steering assister comprises: a reducer including a worm wheel connected and rotated with the steering shaft, and a worm shaft tooth-meshed with the worm wheel to rotate the worm wheel which is connected with the steering shaft; and the first motor configured to rotate the worm shaft in a forward or reverse direction according to a control signal input from the electronic control unit, and wherein the second steering assister comprises: the oil pump coupled to the second motor to deliver the hydraulic oil; a screw nut sliding to one side or another side according to the hydraulic pressure of the hydraulic oil; a gear box housing accommodating the screw nut and having a first cylinder and a second cylinder, which are filled with the hydraulic oil, on one side and another side with reference to the screw nut; and a sector shaft accommodated in the gear box housing and tooth-meshed with the screw nut to rotate in a forward or reverse direction when the screw nut slides, thereby operating a pitman arm.