| 摘要 |
PURPOSE:To permit back pressure control, good in response property and high in accuracy, by a method wherein torque limiter control, limiting the upper limit of output of a motor in accordance with the set value of back pressure, is effected. CONSTITUTION:A pressure-detecting signal, outputted from a back pressure sensor 15, is converted into a pressure-detecting signal (ep) in a converting circuit 20 and is supplied to an adding point A. A pressure commanding signal (epi) outputted in accordance with the set value is supplied to the adding point A from a back pressure setter 21. As a result, the difference signal of epi-ep=DELTAep is outputted from the adding point A and is amplified by a pressure control amplifier 22 to output an electric current commanding signal DELTAepo. An output limiting circuit 32 inputs the electric current commanding signal DELTAepo and a signal (epi'), which is the pressure commanding signal (epi) amplified by the amplifier 31, and limits the upper limit of the electric current commanding value in accordance with the magnitude of the pressure commanding value. Then, the amplifying degree of the pressure control amplifier 22 is increased to enlarge the electric current commanding signal DELTAepo' and whereby the back pressure control, in which the back pressure arrives at the set value thereof quickly, may be effected. |
