| 摘要 |
PURPOSE:To enable a fluid device to be controlled with high accuracy by closing both negative pressure port and atmospheric port with a single valve body to maintain pressure in the fluid device at a certain value. CONSTITUTION:Pressure in a pressure chamber 102 of an EGR valve 100 is controlled according to the ratio of respective pulse widths of negative pressure introducing signal A and atmosphere introducing signal B supplied to the input of a drive circuit 600. Also, when any of the respective signals A, B is not supplied to the input of the drive circuit 600, a valve body 202 closes both ports 205, 206 to hold pressure in the pressure chamber 102. Thus, pressure variation in the pressure chamber 102 can be restrained to provide high accuracy control. |
