VAF instruments VISCOSENSE 2, Техническое руководство

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8
2.3 PRINCIPLE OF OPERATION
操作原理
The patented measuring principle is based on rotational vibration of a pendulum in liquid.
已获得专利权的测量原理系以传感器探头在流体中的旋转振动为基础
The sensor consists of a sensor head (1) attached to a base plate (2) by a torsion tube (3). Two sets
of piezo-electric elements (4) are positioned inside the pendulum. One set drives the pendulum, the
other set measures and controls the rotational movement of the pendulum via a feedback circuit. In
this way the pendulum is kept in vibration at its resonance frequency.
传感器系由通过扭管
(3)
固定在基座
(2)
上的钟摆
(1)
组成。钟摆内置两套压电陶瓷元件
(4)
。一套驱动钟
摆，而另一套通过反馈信号测量和控制钟摆的旋转动作。这样使钟摆在其共振频率上保持振动。
Measuring the resulting frequency at two specific values of phase difference, yields a value for the
damping which is proportional to the square root of the dynamic viscosity.
测量相位差两点的频率，得出衰减值。这一数值与动力黏度的平方根成正比。
A flow tube (5) is placed around the pendulum, to protect it against mechanical damage.
流管
(5)
被置于钟摆外围，以保护钟摆避免机械损坏。
The flowtube is machined with a smooth surface, as well as with a triplet of oval slits. These slits
increase the refreshing rate between sensor and flowtube.
流管经过精细机加工处理，表面光滑并有三个椭圆形开口。这些开口增加了传感器探头和流管之间的
更新速率。
Figure 3 ViscoSense
®
2 sensor
图
3
扭转振动传感器探头