JPS58154617A - Vortex flow meter - Google Patents

Abstract

PURPOSE:To improve vibration resisting performance and to produce a vortex flow meter with improved SN, by fixing a detecting sensor on a position where noise due to disturbance is about zero. CONSTITUTION:A force receiving body 2a has a free end at its insersion point and is fixed on a conduit 1 at its intermediate part. A fixing body 5 is inserted into a recessed part 21 with a gap 51 to press and fix a stress detecting part 3 to/on the required position of the recessed part 21. Bending moment M, force F and tare weight W act on the lower part of the fixing body 5 by the disturbance vibration, bending moments M21-M23 based upon said loads are generated and M2 is generated as a composite bending moment. If the stress detecting part 3 is arranged on a position A or B where vibration bending moment M2 O is formed, noises due to disturbance vibration can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a vortex flowmeter K11l that measures the flow rate of fluid by utilizing Karman vortices.

It has been known for a long time that when an object is placed in a fluid, vortices are generated regularly and alternately from both rear surfaces of the object, and flow downstream in the form of a full moon. This O vortex street is called a Karman vortex street, and the number of vortices generated per unit time am (vortex frequency) is proportional to the flow velocity of the fluid.

Therefore, a vortex generator is placed in the pipe that guides the fluid to be measured, and a piezoelectric element, a strain gauge, a capacitance, an inductance, etc. equipped with a vortex generator (t or force receiving body) absorbs the lift change caused by the generation of the vortex. Vortex flowmeters have been put into practical use that measure the flow velocity and flow rate of fluids by detecting and converting signals. By the way, this type of vortex flowmeter is affected by external tm movements such as piping vibrations excited by pumps etc. at low flow rates of ff and 4tK.

There was a drawback that the I ratio deteriorated.

When used for food, etc., the pipe line is 0 from a sanitary O point of view.
The end of the vortex generator of the base must be made a free end, but in this case, it is difficult to eliminate the above-mentioned drawbacks of 4IK. Below, according to the diagram 1! FIG. 1 is a diagram illustrating the configuration of a conventional example that is commonly used.

In the figure, 1 is a cylindrical pipe through which the fluid to be measured flows, and 2 is a columnar force receiving body inserted into the pipe 1. It is made of stainless steel, and one end is fixed to the pipe IKl [l], and the other end is a free end. It is in a state. 21 is a recess provided in the force receiving body 1;
This is a nine-disk-shaped stress detecting section provided in the shallow recess, and its center axis is on the center axis of the force receiving body 2. In this case, the stress detection section 5 consists of a disk-shaped element body 31 and electrodes 32, 33, and 34, as shown in FIG. The electrode 32 has a thin disk shape and is provided on one side of the element body 31. On the other hand, the electrodes 33 and 34 are approximately arcuate and have the center of the element body 31 sandwiched between them on the other side of the element body 31. They are arranged symmetrically in a direction perpendicular to the flow of the measuring fluid. In this case, a piezoelectric element is used as the element body 31. Reference numeral 4 denotes a stone-bonded body which is not made of an insulating material, but which seals the stress detection part S in the recess 21 insulatingly from the recess 21. In this case, a glass material is used.

In the above configuration, when the fluid to be measured flows into the pipe 1, an alternating force as indicated by the arrow X shown in FIG. 1 acts on the 14-force body 21 due to the Karman vortex. (Hereinafter, this direction will be referred to as the "lift direction") This alternating force is transmitted to the stress detection s5 via the sealing body 4.

In this case, as shown in FIG. 1, stress changes occur in the force-receiving body 2 in opposite directions across the central axis of the force-receiving body 2. An electric signal (for example, a change in electric charge) corresponding to this stress change is generated between the electrodes 32 and 33 and the electrodes 32 and 34 of the stress detection section 5. If the number of times of this change is detected, the detection frequency of K and P vortices will be delayed. Therefore, the electrode 32-
Electrode 33. If the electrical output between the electrodes 32 and 34 is processed differentially, twice the electrical output can be obtained.On the other hand, vibration noise propagating through the pipes, such as pumps, compressors, The entire pipeline vibrates due to vibration noise caused by the opening and closing of the -.

Due to this vibration, an alternating bending moment based on the mass distribution of the force receiving body 2 acts on the force receiving body 2 in the direction in which the aforementioned alternating force X acts. The stress generated in the force body 2 is detected as noise by the stress detection section 5.

Figure S shows this bending moment ~, so M8
The police box O-ran caused by the company employee is a moment 0 In this case, the mode of action of the police box O-game M8 caused by the vortex generation and the vibration noise moment is almost the same. It can only be used under the following conditions. Therefore, if emphasis is placed on vibration resistance performance, the lower limit of measurable flow velocity will not reach the range where it is commonly used.On the other hand, if emphasis is placed on the lower limit of measurement, vibration resistance performance will not reach the range where it is commonly used. It is a solution to a problem.

An object of the present invention is to provide a vortex flow needle with improved vibration resistance and a good 8/N ratio. FIG. 4 is an explanatory diagram of the configuration of an embodiment of the present invention.

In the figure, the same symbols as in FIG. 1 indicate the same functions. Hereinafter, only the differences from FIG. 1 will be explained.

2a is a columnar force receiving body inserted into the conduit 1, and is made of stainless steel. The insertion tip of the force receiving body 2m is in a free end state, and the middle part thereof is fixed to the conduit 1.

S is a fixed body that is inserted into the recess 21 with a gap 51 and fixes the stress detection section 5 in a predetermined position (described later) K in the recess 21 while suppressing it. The fixed body 5 is fixed at the open end of the recess 21, and in this case, it is fixed by welding 52.

In the above configuration, when a document force acts on the force receiving body 2K based on the generation of a vortex, the force receiving body 2 is displaced at a certain moment as shown in FIG. , the arrow X in the figure represents the acting force. Focusing on the fixed body 5, as shown in FIG. 6, a bending moment M and a force F due to the fact that the force receiving body 20 is fixed are applied to the lower end of the fixed body 5. However, bending moment based on each) M engineering 19M□2 is generated.

A town is generated as a resultant bending moment of these.

On the other hand, due to pipe vibration etc., the force receiving body 2 vibrates as a whole, and its displacement at a certain moment becomes as shown in FIG. 1 fixed body as mentioned above! [If we pay attention to this, as shown in FIG. 8, a bending moment M, a force F, and its own weight W act on the lower end of the fixed body 50 based on the disturbance vibration, and a bending moment M2□t M2□9M23 is generated based on each of them. M2 is generated as a resultant bending moment.

(Vibration Bending Moment in FIG. 6) By distributing power to the M24 zero position, that is, the illustrated M or BK stress detection unit 5, the disturbance vibration noise can be reduced.

As a result, the BIN ratio against disturbance vibration can be improved. ! l! In the embodiment, a stress detection section 5 made of a piezoelectric element is used as a detection sensor. However, the present invention is not limited to this, and a strain gauge may be used, for example. Any device that can detect the alternating force acting on the body 21L may be used.

In addition, in the above-mentioned embodiment, nine examples have been described in which the force receiving body 2a also serves as a vortex generating body, but the vortex generating body is
It goes without saying that the vortex generating body may be made separately from the body or the vortex generating body may be placed upstream of the force receiving body 2a.

As explained above, according to the present invention #4, it is possible to realize a vortex flow needle with improved vibration resistance and a good 87N ratio.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a conventional example embodiment that has been generally used in the past, and FIGS. 5 to 8 are explanatory diagrams of the operation of FIG. 4. DESCRIPTION OF SYMBOLS 1... Pipeline, 2a... Force receiving body, 21... Recessed part, 5
... Stress detection part, 5 ... Fixed body, 51 ... Gap,
52...Fixed. Agent: Patent Attorney Nobuo Kozawa No. 1 [ll
Dream 3 Mouth'440
Figure 5: 6 yen! J7 Figure 2
43 Figure

Claims (1)

[Claims] a pipe line through which a measurement fluid flows; a columnar force-receiving body having one end inserted into the cough pipe line in a free end state and a part thereof attached to the pipe line;
A recess provided on the other end side of the body force receiving body, a detection senna disposed in the recess, and a detection senna inserted into the recess with a gap, one end of which is fixed at the open end of the recess, and the senna is subjected to disturbance force. A vortex flowmeter that is equipped with a fixed body that is fixed at a position where the based noise is almost zero.