Patent ID: 8066091
Filing Date: 2011-11-29
Classification: B62D

Abstract:
1. A steering system comprising: an input cylinder having a first hydraulic chamber and a second hydraulic chamber; a transmission mechanism, wherein a transmission efficiency for converting and transmitting a linear motion of the input cylinder to a rotary motion of a steering wheel is less than a transmission efficiency for converting and transmitting the rotary motion of the steering wheel to the linear motion of the input cylinder; an output cylinder connected to a steerable vehicle wheel and having a third hydraulic chamber and a fourth hydraulic chamber; a first hydraulic passage for connecting the first hydraulic chamber to the third hydraulic chamber; a second hydraulic passage for connecting the second hydraulic chamber to the fourth hydraulic chamber; a first hydraulic circuit including the first hydraulic chamber, third hydraulic chamber, and first hydraulic passage; a second hydraulic circuit including the second hydraulic chamber, fourth hydraulic chamber, and second hydraulic passage; a flow rate control mechanism for adjusting the ratio of the hydraulic oil quantities in the first hydraulic circuit and the second hydraulic circuit that flow between the first hydraulic chamber and the third hydraulic chamber through the first hydraulic passage, and flowing between the second hydraulic chamber and the fourth hydraulic chamber through the second hydraulic passage in order to keep unchanged the quantities of hydraulic oil in the first hydraulic circuit and the second hydraulic circuit; a steering actuator for providing the steerable vehicle wheel with a steering power assistance; and a controller for cooperatively controlling the flow rate control mechanism and the steering actuator; wherein the flow rate control mechanism comprises: a cylinder tube; a piston for defining, in the cylinder tube, a fifth hydraulic chamber connected to the first hydraulic circuit and a sixth hydraulic chamber connected to the second hydraulic circuit; an electric motor; and a conversion gear for converting a rotary motion of the electric motor to an axial motion of the piston, the conversion gear having irreversibility for suppressing power transmission from the piston to the electric motor.