[0021] Referring to Figures 1-4, this figure shows an ultrasonic vortex flowmeter 10 according to the present invention, which has a flowmeter holder 12 formed by a metering head 14 pivotally mounted on a slidingly mounted fork 16. The fork 16 is arranged to cooperate with a separate sliding sleeve of the pipeline connector 18 containing a bluff body, and is held in place by a locking special-shaped pin 20. In addition, a pair of rubber bushings 21 are respectively placed in the cavities 23 and 25 formed on the opposite sides of the inner side of the fork 16, and are made to slightly extend outward from the inner surface of the fork, so that once the fork is shaped When the member 16 slides, a friction fit is formed between the fork member 16 and the pipeline connector 18 containing the bluff body.
[0022] In the initial installation, the pipeline connector 18 containing the bluff body is assembled to the liquid pipeline or pipeline, after which the flow liquid to be detected enters a flow channel 24 containing the bluff body through the first open end 22 , And finally flow out through a second open end 26 opposite to the first open end 22. At least one bluff body 28 is fixed to the pipeline connector 18 so that it is positioned in the channel 24 and extends inward.
[0023] The metering head 14 according to the present invention provides two isolated circuit compartments 30 and 32. The first compartment 30 houses the sensor circuit (described below in conjunction with FIG. 5) and is sealed with an end cap 36 after installation. The second compartment 32 is closed by a detachable end cover 38, and is equipped with different connections for connecting the output end of the flowmeter with the external monitoring and control circuit after the flowmeter is installed. All components of the flowmeter holder are made of corrosion-resistant materials such as nylon, Teflon, polyvinyl chloride, polyvinylidene fluoride or other suitable plastics. The use of plastic enables the flowmeter of the present invention to have corrosion resistance, acid resistance and resistance to most solvents, and it is very suitable for hazardous industrial production environments.
[0024] The ultrasonic transmitter 40 and receiver 42 are positioned near the rubber bushing 21 inside each corresponding cavity 23 and 25. It is easy to see from Figure 3 that when the fork is properly installed on the pipeline connector 18 containing the nonlinear body, the transmitter and receiver will be positioned in such a way that even when an ultrasonic signal is not contained in the non-linear body The liquid flow in the channel 24 of the streamlined body collides with the bluff body 28 to generate a downwardly flowing vortex 43 to pass through, which can be easily understood by those skilled in the art. A phase detection circuit such as an exclusive OR gate 44 is used to detect a phase difference between the transmitted wave and the received wave caused by the eddy current 43. A more complete description will be given below in conjunction with the flowmeter processing circuit in FIG. 5.
[0025] As shown in FIG. 5, to be more precise, the processing circuit 100 includes an oscillator 102, which generates a reference wave with a frequency of, for example, 2 MHz. The reference wave is then divided by a frequency divider 103, for example, and input to the transmitter 40 to generate a transmission wave. The output of the oscillator 102 is also provided to the XOR gate as one of the inputs through the second frequency divider (as shown in the 2-frequency divider 105), and the output of 42 is received as the other input of the XOR gate 44. As shown in Figure 6(b), the exclusive OR gate 44 then generates an output signal 46 composed of a series of pulses with a certain width, which is the phase difference between the transmitted wave and the received wave shown in Figure 6(a). a" function.
[0026] The output of the XOR gate 44 is filtered by a low-pass filter whose cut-off frequency is lower than the carrier frequency but higher than the frequency at which eddy currents occur. The low-pass filter 104 effectively removes the carrier wave from the phase detector output. Therefore, as shown in the exemplary embodiment shown in FIG. 6(c), if a standard CMOS-type XOR gate is used, the output of the low-pass filter 104 includes a phase difference that varies between 0 and 5 volts (DC). The corresponding DC voltage component and a small AC voltage component whose frequency is a function of liquid flow velocity. A high-pass filter 106 separates the AC voltage component for input to the control processor 108. The control processor 108 processes the AC component for output to a digital-to-analog converter (DAC) 110. The output of the DAC is sent to a suitable liquid flow display 112 or other external monitoring device.
[0027] According to the present invention, when the phase difference between the transmitted wave and the received wave is substantially 0 or 180 degrees, to compensate for the inability of the exclusive OR gate 44, when the phase difference between the transmitted wave and the received wave is substantially An output is generated from 0 to 180 degrees, and the control processor 108 uses an analog-to-digital (A/D) converter 114 to monitor the amplitude of the DC component output by the XOR gate to determine when the phase difference is substantially 0 or 180 degree. For example, in the above exemplary embodiment, when the phase difference is in an optimal range, the amplitude of the DC component is 2.5 volts (direct current), and when the phase difference is substantially 0 or 180 degrees, the amplitude of the DC component is respectively 0 or 5 volts (DC). When the phase difference detected by the processor 108 is equal to or close to 0 or 180 degrees, the processor 108 activates a switch 116 so that the input of the oscillator/transmitter to the XOR gate is reversed by the inverter 118. Due to the use of the frequency divider 105, the setting of this switch effectively produces a 90-degree phase shift in the signal input from the transmitter to the XOR gate 44, thereby maintaining the phase difference between the transmitted wave and the received wave in an optimal phase detection range in.
[0028]Therefore, the ultrasonic vortex flowmeter 10 of the present invention has significant advantages over conventional liquid flowmeters. In particular, the sliding assembly fork can be unlocked and quickly removed and replaced, and there is no need to open the liquid flow pipeline when maintaining the flowmeter. Therefore, the possibility of external contaminants entering the liquid when the flowmeter needs to be repaired is eliminated. Sex. Furthermore, the device of the present invention for monitoring the deviation from an optimal phase difference detection range and the subsequent 90-degree phase shift compensation enables the present invention to use a simple, reliable and inexpensive XOR gate as a phase detector. Finally, because the configuration of the flowmeter head isolates the respective intervals for the flowmeter circuit and the field connections, for field workers, after installation, simply connect an external monitor or other control device to directly check and expose the flow rate.计Circuit.
[0029] It should be understood that the foregoing description of the preferred embodiments of the present invention is only for the purpose of illustrating the present invention, and various different structures and structures disclosed herein are provided without departing from the concept of the present invention and the scope defined in the claims. The operating characteristics allow for various improvements.
