| 摘要 |
PROBLEM TO BE SOLVED: To prevent the deterioration of a steering feeling by increasing the opening degree of a variable throttle mechanism to match an increase in a control flow rate only when an engine revolution number exceeds a set revolution number in the traveling region of a vehicle. SOLUTION: In accordance with a change in the load pressure of a power cylinder C, a controller 12 gradually changes a current supplied to a solenoid 11. In other words, in accordance with the increase of a control flow rate from a lowest flow rate to a flow rate necessary for an assist force, the opening degree of a variable throttle part 10 is gradually increased. As the opening degree of the variable throttle part 10 is increased, a flow rate passing through a second control valve 7 is increased, in other words, a flow rate passing through a first control valve 6 is reduced. Thus, as the control flow rate is increased, the sudden increase of the pressure of the power cylinder C is prevented, no uncomfortable feeling such as the shifting of a handle for a driver is prevented, and a steering feeling is improved. |
