Steering device

A steering device comprising:

• a steering mechanism having a steering shaft and a transmission mechanism, wherein
• the steering shaft has a first shaft, a second shaft, a third shaft, a fourth shaft, a first torsion bar and a second torsion bar,
• the first shaft and the second shaft are connected to each other through the first torsion bar,
• the first shaft can be rotated according to driver's steering operation,
• the third shaft is connected to the second shaft,
• the third shaft and the fourth shaft are connected to each other through the second torsion bar,
• the third shaft has a third shaft valve portion,
• the fourth shaft has a fourth shaft valve portion, forms a rotary valve together with the third shaft, and can selectively supply working fluid, which is externally supplied, to a first fluid chamber and a second fluid chamber according to torsion of the second torsion bar, and
• the transmission mechanism transmits rotation of the fourth shaft to steered wheels;
• an electric motor having an electric motor output shaft and being able to rotate according to a motor command signal generated on the basis of a steering torque signal;
• a reduction gear provided between the electric motor output shaft and the second shaft and transmitting a rotation force of the electric motor to the second shaft;
• a first housing having a first housing body, a sensor accommodating space and a reduction gear accommodating space, wherein
• the first housing body is formed as a single-piece member by molding,
• the sensor accommodating space is provided at an inner side of the first housing body, and
• the reduction gear accommodating space is provided at the inner side of the first housing body, and accommodates the reduction gear;
• a second housing having a second housing body, a rotary valve accommodating space, a fourth shaft accommodating space and a fluid chamber, wherein
• the second housing body is connected to the first housing,
• the rotary valve accommodating space is provided at an inner side of the second housing body, and accommodates the rotary valve,
• the fourth shaft accommodating space is provided at the inner side of the second housing body, and accommodates the fourth shaft, and
• the fluid chamber is provided at the inner side of the second housing body;
• a piston provided inside the second housing, dividing the fluid chamber into the first fluid chamber and the second fluid chamber and providing a steering force to the transmission mechanism according to a pressure difference of the working fluid between the first fluid chamber and the second fluid chamber;
• a torque sensor provided in the sensor accommodating space, detecting a steering torque generated at the steering mechanism according to a torsion amount of the first torsion bar and outputting the steering torque signal;
• and
• a control unit including a microprocessor, wherein
• the microprocessor is configured to generate the motor command signal on the basis of the steering torque signal.