笔者单位1996年从日本小池酸素公司购进的数控火焰气割机,使用中割矩自动升降系统经常发生故障,表现为上不去、下不来或者上下都不动,导致割矩托架撞坏,严重影响生产。这种自动升降控制线路采用电容感应式,如图1所示(只画出与之相关的部分线路图)当电容环与钏板之间的距离发生变化时,其间的感应电容量随之变化,其信号经放大器、比较器放大后触发电子开关 I_(C1)。当此距离过大时,电容量减小,信号 The author units in 1996 from Japan Kotobukiya purchased NC flame gas cutting machine, the use of cutting torque automatic lifting system often fails, the performance can not go up or down or up and down are not moving, resulting in cutting moment bracket crash, serious affect production. This automatic lifting control circuit using capacitive sensing, as shown in Figure 1 (only draw the relevant part of the circuit diagram) When the capacitance between the ring and the plate changes, the sensing capacitance between the change , The signal is amplified by the amplifier, the comparator is triggered to amplify the electronic switch I_ ​​(C1). When this distance is too large, the capacitance decreases and the signal