JPH0450493Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a vortex flowmeter that avoids the inconvenience of external vibrations being measured as erroneous vortex signals during measurement and enables stable and accurate measurement. .

[Prior art]

Most vortex flowmeters detect vortices by converting the amount of stress or strain generated in response to vortex fluctuation pressure into an electrical signal. In this method, the magnitude of the signal is proportional to the square of the flow rate, so attempts were made to increase the gain of the preamplifier in the low flow range and lower the gain in the high flow range to average the output signal level. ing. That is, since the gain is large in the low frequency region, there is a problem in that external vibrations are detected. Vibrations from pumps and the like are transmitted to the piping line in which the vortex flowmeter is installed, and it is particularly affected by lateral vibrations that have low bending rigidity. This vibration also extends to the preamplifier case, so a large compressive stress acts on the main body joint portion of the support tube that joins the preamplifier case and main body due to the moment of vibration. Since this stress acts near the vortex detector, it had a large effect on the vortex detector.

Regarding the above-mentioned problem, the applicant filed a patent application in 1982-
In No. 137708, the joint between the support cylinder and the main body joint is made into partial contact instead of full contact, and the distance between the average points of the contact part is increased, which increases the thickness of the main body at the point of stress application. It was proposed that the vibration resistance increases by increasing the stiffness.

[Problem that the invention seeks to solve]

The conventional method described above is effective when the flowmeter is small, but when the flowmeter becomes large, the plate thickness becomes relatively thin compared to the distance between the contact centers, which reduces the rigidity of the main body and makes it less effective. It was hot.

The present invention was made in response to the above-mentioned problems.

[Structure of the idea]

This invention was made to address the above-mentioned problems and is mainly applied to large vortex flowmeters. That is, the purpose is to increase the rigidity of the flow meter body against the vibration moment received by the inertial body that is the preamplifier, in addition to the force acting on the flow meter body as piping vibration. First, the vortex generator with a built-in vortex detector is not attached directly to the main body, but is attached via a boss portion with strong bending rigidity.

Second, the mounting tube is attached to the main body via a reinforcing plate. The reinforcing plate has high bending rigidity in the vibration direction, and vibration stress is applied to the main body fixing portion at a location that has high rigidity and is distant from the detector. As a result of the above, vibration resistance equivalent to that of a small flow meter can be obtained.

〔Example〕

An embodiment of this invention will be described below with reference to the drawings.

Reference numeral 1 denotes a vortex flowmeter main body having a pipe line 2; 3 indicates a vortex generator installed vertically in the pipe line 2;
It is placed on the upper surface of a boss portion 5 formed by penetrating the tube wall of the tube and is firmly fixed with a desired screw 6. 7
is a recess formed from the top of the vortex generator 3 toward the inside of the conduit 2, into which a desired sensor mechanism 8 is inserted.

That is, this sensor mechanism 8 has a fixed flange 9 sandwiched between the upper and lower cylindrical parts, and a positioning plate 10 is fixed at a desired position by resin molding inside the sensor mechanism 8. A positioning plate 10 is fixed at a desired position with a resin mold at the lower part thereof. sensor 11
A sensor 12 for detecting mechanical vibration is fixed to the upper part of each of the sensors, and a signal can be sent to the preamplifier by a lead wire. and sensor mechanism 8
A pressure-receiving tongue piece 13 is fixed to the lower end of the vortex generating body 3, and a through hole 14 facing the inside of the pipe line 2 is bored at the part of the concave part 7 of the vortex generating body 3 that is located on the tongue piece 13. The vortex signal is obtained so that changing pressure fluctuations can be applied to the pressure-receiving tongue piece 13 through the through hole 14.

Reference numeral 15 indicates a reinforcing plate placed and fixed on the flange portion 4 of the vortex generator 3. This reinforcing plate 15 has left and right ribs 16, 16 facing perpendicular to the direction of fluid flow in the pipe line 2, and has a window hole 17 through which the fixing collar 9 of the sensor mechanism 8 is inserted.
The base flange 20 of the mounting tube 19 having the preamplifier case 18 at one end is attached to the ribs 16 and 1 at the center.
It is firmly fixed to the inner peripheral side of 6 with screws 21 or the like. Moreover, this reinforcing plate 15 has both ribs 16,
Mounting holes 22 near both ends in the longitudinal direction along 16,
22, and a notch 23 is provided across the inner surface of the lower surface of the reinforcing plate 15, which is slightly away from the opening of the lower end of both the mounting holes 22, 22.
The reinforcing plate 15 can be fixed to the vortex flow meter main body 1 via the flange portion 4 of the vortex generator 3 with a desired stopper 25.

The function of this device will be described based on the above structure. When the vortex flow meter main body 1 is connected to a desired pipe and the fluid to be measured is caused to flow, when the fluid to be measured passes through the vortex generator 3, a Karman vortex is generated on the trailing side and a pressure change is caused. is transmitted to the fluid in the recess 7 through the through hole 14 of the vortex generator 3, and the sensor mechanism 8
The pressure-receiving tongue piece 13 is vibrated left and right, and the sensor mechanism 8 is movably displaced about the fixed collar 9 as a fulcrum. This movable displacement is detected by a Karman vortex detection sensor 11 provided in the sensor mechanism 8, and transmitted as a vortex signal to the preamplifier.

By the way, in the pipe line 2, external forces applied to the pipe, such as pump vibrations, mechanical vibrations, and other external vibrations that adversely affect the vortex signal act on the vortex flowmeter. This external vibration is transmitted to the main body attached to the pipe, but the vibration in the main body is detected by the vortex detection sensor 11 and mechanical vibration detection sensor 12, which are arranged symmetrically with the fixed collar 9 in the sensor mechanism 8. The vibrations are detected as having the same phase, and this vibration detection signal is reversely connected and erased.

Vibration acting on the preamplifier generates a moment as the product of the preamplifier's mass and the length of the mounting cylinder, but since it is received by the reinforcing plate with ribs 16 in the direction of the vibration, it has high rigidity and does not lower the resonance frequency. , and since the vibration stress acts on widely separated points consisting of the legs 24, 24, the vibration stress due to the moment is reduced and the sensor mechanism 8
The effect on the fixed flange 9 is small, and the thick boss part increases the rigidity, so the sensor mechanism 8
The vibrational distortion is also small, and the influence of the vibrations mentioned above can be comprehensively eliminated. Although the sensor mechanism 8 has been described as one with vibration compensation, since the present invention relates to the removal of the influence acting on the preamplifier, it goes without saying that the sensor mechanism 8 can be applied even when the sensor is not equipped with vibration compensation.

FIG. 6 shows the results of measuring the vibration characteristics of the vortex flowmeter constructed in this embodiment and a vortex flowmeter that does not use the reinforcing plate 15. As can be seen from this graph, the embodiment of this invention that uses the reinforcing plate 15 does not transmit an erroneous signal, but the one that does not use the reinforcing plate 15 transmits an erroneous signal at frequencies of 40 Hz or higher. I understand.

〔effect〕

According to this invention, it is possible to eliminate the effect of piping vibration on the vortex detection sensor, so a large vortex flowmeter with relatively low rigidity can have the same vibration resistance as a small vortex flowmeter. A stable vortex signal with a high level of vorticity is obtained.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view showing an embodiment of the vortex flowmeter according to the invention, FIG. 2 is an enlarged side view of the main parts of the same, and FIG. 3 is a partially cutaway front view of FIG. 1. Fourth
The figures are a plan view taken along the - line in FIG. 1, FIG. 5 is a reinforcing plate, A is a plan view, B is a front view, and FIG. 6 is a graph comparing vibration characteristics. DESCRIPTION OF SYMBOLS 1... Vortex flow meter body, 2... Pipeline, 3... Vortex generator, 7... Recess, 8... Sensor mechanism, 11...
Sensor for Karman vortex detection, 12... Sensor for mechanical vibration detection, 13... Pressure receiving tongue piece, 14...
Through hole, 15... Reinforcement plate, 16... Rib, 23...
Notch part, 24... leg part.

Claims (1)

[Scope of utility model registration request] A boss portion is formed by penetrating the pipe wall of the conduit, and a vortex generator having a flange portion formed at the top is placed on the boss portion, and the vortex generator is attached to the flange so that the vortex generator is perpendicular to the axis of the conduit. and a boss part are fixed, a recess is bored in the vortex generating body, a sensor mechanism for detecting vortex fluctuating pressure is inserted into the recess, and a fixing collar of the sensor mechanism is fixed to the flange part. It is a flow meter,
A reinforcing plate provided with ribs perpendicular to the axial direction of the conduit and having a hole through which the sensor mechanism is inserted is fixed to the flange portion so as to surround the fixing collar of the sensor mechanism, and a preamplifier is attached to one end of the reinforcing plate. The base flange of the mounting tube that supported the case is fixed to the inner circumferential side of the rib of the reinforcing plate, and further, the reinforcing plate and the flange are fixed to the outer circumferential side of the fixed position of the base flange of the mounting tube. A vortex flowmeter characterized in that a notch is provided across the inner surface of the lower surface of the reinforcing plate so that a fixing surface is formed.