02-3 计测仪器上应用 压电流量计 计数器CH-EN OK.doc

六、压电流量计 flow meter流量计是按传感器探头插入管道并刚好接触流体来进行设计的。传感器探头顶部承受流体切应力的大小正比于流体的流量。The design of flow meter is according to the sensor probe inserted into the pipe and just touching the fluid. Fluid shear stress on the top of sensor probe is in direct proportion to the volume of fluid flow.如图3.28所示，图3.29是图3.28中检测探头的放大图。在这两图中1为管节部分，2为金属制的管节外壳，3为管子衬套，4为位置调节螺杆，5为T型管节(即孔腔)，6为法兰盘，7为孔腔衬套，8为探头，9为探头顶部，10为探头体，11为底板，12为衬垫，13为接地引线，14为信号引线，15为压电陶瓷传感器，16为同轴电缆的中心线，17为同轴电缆的接地屏蔽线，18为绝缘子，19为信号放大器，20及21为法兰盘，22为遥控指示电路，23为电源电路。As shown in Fig.3.28, Fig.3.29 is detector probes magnification of Fig.3.28. In these two figures,1-the part of pipe section, 2-the metal shell of pipe section, 3-the pipe bushing, 4-the adjusting screw of position, 5-the T type pipe section ( i.e. Hole cavity),6-the flange plate;7-the bushing of hole cavity;8-the probe,9-the top of probe, 10-the probe body,11-the baseboard,12-the pads, 13-the GND wire, 14-the signal wire, 15-the piezoelectric ceramic sensor,16-the center line of coaxial cable, 17-The GND shielding wire of coaxial cable, 18-the insulator, 19-the signal amplifier, 20 and 21-the flange plate, 22-the remote indication circuit, 23- the power supply circuit.图:3.28 流量计纵剖面图和插入检测装置的电路方框图.图:3.29 放大的检测探头把T型管节用螺栓拧紧在被测流体管道的管接头法兰盘上,在T型管节中插入流量计探头就可测量流体速度。Screw the T type pipe section down on the flange plate with detected fluid pipe connection and measure the fluid speed with a flow meter probe inserted in T type tube.七、压电计数器Piezoelectric counter压电计数器由一双膜片型压电元件和图3.49所示的检测电路构成。 当物品G落到压电陶瓷元件5上时，由于压电陶瓷元件的压电效应产生电信号，此电信号经可控硅整流器的栅极使可控硅导通，经电阻R1加到晶体管4的基极上，导通集电极和发射极，启动磁继电器，使计数器工作。 Piezoelectric counter consists of a double diaphragm type piezoelectric element and the detection circuit shown in Fig.3.49. When the item G falls down to the piezoelectric ceramic element 5, the electrical signal produced by piezoelectric effect of piezoelectric element will conduct SCR via grid electrode of SCR rectifier, which will conduct collector and emitter to start magnetic relay and make the counter work with R1 added to the base electrode of transistor.图:3.29压电计数器线路图 当压电陶瓷元件接受下一个物品再进行动作时，因为电源电流直接为最初的逆极性成分所截止，因而压电陶瓷元件接受物品的反应次数能正确地由磁继电器的开闭而进入计数器，并进行运算。这样，这种简单的装置能够正确地、灵敏地对落到压电陶瓷元件上的物品进行计数和记录。When the piezoelectric ceramic element receives next item and acts again, and the supply current is directly cut off by the original composition of reverse polarity, the reaction times of piezoelectric ceramic element receiving items will correctly make the counter work and calculate via magnetic relays opening and