JPH0448499Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a flowmeter, and more particularly to a flowmeter that uses a magnetic coupling to transmit the number of rotations of a rotating body corresponding to the flow of a fluid to be measured to a measuring section.

2. Description of the Related Art For example, in a large-capacity gas meter, a magnetic coupling is used as a means for transmitting the rotation of a rotating body that rotates in response to the flow rate of a fluid to be measured to a measurement unit that performs flow rate measurement processing. This magnetic coupling has a partition wall that liquid-tightly or air-tightly defines the flowmeter main body, which has a rotating body inside that rotates in response to the flow rate of the fluid to be measured, and the measurement section, and a partition wall that faces each other through the partition wall. A pair of magnets are provided. The first magnet is arranged on the rotating body side and rotates integrally with the rotation of the rotating body, and the second magnet is arranged on the measuring part side and connected to the input shaft of the measuring part,
The first magnet rotates in conjunction with the rotation of the first magnet via magnetic force, thereby transmitting the rotation of the rotating body to the measuring section while sealing the fluid to be measured.

Problems to be Solved by the Invention However, in the conventional flowmeter described above, the magnetic coupling consisted only of a pair of magnets that were placed opposite each other with a partition wall that defined the flowmeter body and the measurement section. However, there was a problem in that it could only be used as a mechanism for transmitting the rotation of the rotating body to the measurement unit while sealing the fluid to be measured. It is also known that long-term use of a flowmeter causes the rotation transmission mechanism inside the measurement unit to deteriorate and the rotational torque required to rotate the input shaft to increase over time. The second magnet becomes difficult to rotate and cannot rotate in response to the first magnet, and a phase difference occurs between the rotations of both magnets, making it impossible to accurately measure the flow rate. Conventional flowmeters have a problem in that the only way to determine the increase in rotational torque is to disassemble the magnetic coupling and measure the rotational torque of the input shaft, which makes maintenance cumbersome. Furthermore, if a flowmeter is used without noticing the increase in rotational torque, there is a problem in that the accuracy of flow measurement decreases and the instrumental error performance (durability, etc.) of the flowmeter decreases.

Therefore, an object of the present invention is to provide a flowmeter that solves the above-mentioned problems by providing a pickup for detecting rotation in a magnetic coupling.

Means and Effects for Solving the Problems In order to solve the above problems, the present invention includes a magnetic coupling that transmits the rotation of the rotating body corresponding to the flow rate of the fluid to be measured to the measurement unit that measures the flow rate. This flowmeter is equipped with a pick-up that detects the rotation of the magnet in the magnetic coupling. With the above configuration, the rotation of the rotating body can be detected using the magnet provided in the magnetic coupling.

Embodiment FIG. 2 shows a longitudinal sectional view of an embodiment of the flowmeter according to the present invention. A flowmeter 1 shown in the figure measures the flow rate of a large volume of a fluid to be measured (for example, gas), and is generally comprised of a flowmeter body 2, a magnetic coupling 3, a measuring section 4, and the like. The flow meter main body 2 has a rotating body (roots) 6 in a fluid flow path 5 through which the fluid to be measured flows, and this rotating body 6 has its shaft 7 rotatably supported by the flow meter main body 2. It is configured to rotate in accordance with the flow rate of the fluid to be measured. A gear 8 is attached to one end of this shaft 7, and this gear 8 meshes with a reduction gear 9. Therefore, the rotation of the rotating body 6 is reduced by a predetermined reduction ratio, and the reduced rotation is transmitted to the output shaft 10. Further, the output shaft 10 is connected to the magnetic coupling 3.

The magnetic coupling 3 is attached to the front cover 2a of the flowmeter main body 2, and is interposed between the flowmeter main body 2 and the measuring section 4, and rotates while maintaining the flowmeter main body 2 and the measuring section 4 airtight. The rotation of the body 6 is transmitted to the measuring section 4. This magnetic coupling 3 is shown enlarged in FIG. As shown in the figure, the magnetic coupling 3 includes a case 11, a pair of magnets 12 and 13, a driving shaft 14, a driven shaft 15, pick-ups 16 and 17, and the like. The case 11 uses a space formed inside as a partition wall 1.
8 airtightly defines a chamber 11a on the flow meter main body side and a chamber 11b on the measurement section side. This partition wall 18 is fitted into the case 11 and its lower part is fixed by a fixing ring 19, so that the case 11
It is attached to 1. Also, chamber 1 on the flow meter main body side
A cylindrical driving magnet 12 (shown with a satin finish in the figure) fixedly attached to the driving shaft 14 is inserted into 1a. The driving shaft 14 has its upper part supported by a bearing part 18a formed in the partition wall 18, and its lower part supported by a bearing part 20a formed in a support member 20 that closes the lower opening of the partition wall 18. Therefore, the main magnet 12 is configured to be freely rotatable within the chamber 11a on the flow meter main body side. Note that the support member 20 is fixed to the lower opening of the partition wall 18 by a fixing ring 21, and an O-ring 2 provided on the outer periphery thereof.
2 and 23 prevent the fluid to be measured from entering the chamber 11b on the measuring section side. Furthermore, the aforementioned output shaft 10 (shown in FIG. 2) is connected to the lower end of the main drive shaft 14.

The driven magnet 13 (shown with a satin finish in the figure) has an annular shape, and is provided in the chamber 11b on the measuring section side so as to face the main driven magnet 12 with a partition wall 18 in between. This driven magnet 13 is attached to a holder 24, and the holder 24 is rotatably supported by a bearing 25 attached to the upper part of the partition wall 18. ) is connected to a driven shaft 15 that is fixed. Further, the driven shaft 15 is supported by a bearing 26 attached to the upper part of the case 11. Therefore, the driven magnet 13 is configured to be rotatable within the chamber 11b on the measuring section side. Also, the main and driven magnets 1
2 and 13 are configured to exert magnetic force on each other through the partition wall 18, so when the main drive magnet 12 rotates with the rotation of the main drive shaft 14, the driven magnet 13 also rotates at the same rotation speed as the main drive magnet 12. Rotate with . Therefore, the rotation of the main driving shaft 14 is caused by the rotation of the driven shaft 15 between the chamber 11a of the flow meter main body and the chamber 1 on the measuring section side.
1b while keeping it airtight.

The pickups 16 and 17 are magnetoelectric conversion elements (for example, Hall elements, magnetoresistive elements, etc.), and generate rotation detection signals in response to changes in the magnetic field. 1st
The pick-up 16 is provided on the partition wall 18 at a position where the magnetic field of the main magnet 12 reaches, facing the main magnet 12. Further, the second pickup 16 is provided opposite to the driven magnet 13 at a position where the magnetic field of the driven magnet 13 of the case 11 reaches. Each magnet 1
2 and 13 are magnetized in the directions indicated by N and S in the figure, and therefore, each pickup 16 and 17 generates a rotation detection signal corresponding to the rotation of the driving magnet 12 and the driven magnet 13, respectively. That is, in the flowmeter 1 according to the present invention, by providing the magnetic coupling 3 with the pick-ups 16 and 17, the magnetic coupling 3 not only has the function of transmitting the rotation of the driving shaft 14 to the driven shaft 15 in an airtight manner, but also has the function of transmitting the rotation of the driving shaft 14 to the driven shaft 15 in an airtight manner. It has a function of detecting rotations of 12 and 13.

As shown in FIG. 2, the measuring section 4 is attached to the front cover 2a of the flowmeter 1, and the indicating section 27 is driven by the rotation of the input shaft connected to the driven shaft 14 of the magnetic coupling 3. The display is configured to display information corresponding to the flow rate of the fluid. This instruction section 2
7 can be read through the window 28.

Now, returning to FIG. 1 again, the pick-ups 16 and 17 provided on the magnetic coupling 3
This will be explained in more detail below. As mentioned above, the first
The pick-up 16 of the main magnet 12 and the second
The pickups 17 can detect the rotation of the driven magnets 13, respectively. Therefore, by comparing the rotation detection signals generated by each pickup 16, 17, it is possible to determine whether both magnets 12, 13 are rotating at the same rotation speed.
In other words, it can be determined whether the driving shaft 14 and the driven shaft 15 are rotating at the same rotation speed. As mentioned above, by using the flowmeter 1 for a long time,
It is known that the rotational torque of the input shaft of the measurement unit 4 increases. As the rotational torque of the input shaft increases, the rotational load on the driven shaft 15 and driven magnet 13 connected to it increases, and when this load exceeds the strength of the magnetic force acting between both magnets 12 and 13, both A phase difference occurs between the rotations of the magnets 12 and 13. The relationship between this increase in rotational torque and the phase difference generated between both magnets 12 and 13 is shown in FIG. In the figure, arrow A indicates the case where gas is used as the fluid to be measured, and arrow B indicates the case where liquid is used as the fluid to be measured. As shown in the figure, the phase difference and the rotational torque are in a proportional relationship, and therefore, by knowing the phase difference, the magnitude of the rotational torque can be determined. Generally, when the rotational torque exceeds a predetermined value (for example, 350 g-cm in Figure 3, indicated by the broken line in the figure. This value varies depending on the type and properties of the fluid being measured), the instrumental error performance deteriorates and the measurement accuracy is known to exceed a predetermined permissible range. Therefore, if the phase difference at which the rotational torque reaches the predetermined value is known and the flowmeter is configured to issue a warning when the phase difference between the magnets 12 and 13 reaches that value, the flowmeter can be disassembled. You can know the increase in rotational torque without
Deterioration of instrumental error performance and measurement accuracy can be prevented.

The rotational phase difference between the magnets 12 and 13 can be detected using pickups 16 and 17.
This configuration is shown in FIG. As shown in the figure, each pickup 16, 17 is connected to a phase comparison control circuit 30 via an amplifier 29, and the phase comparison control circuit 30 is also connected to an alarm 31. Each pickup 16, 17 simultaneously detects the rotation of the main magnet 12 and the driven magnet 13, respectively, and generates a rotation detection signal. These rotation detection signals are individually amplified by amplifiers 29 and then sent to a phase comparison control circuit 30.
is supplied to The phase comparison control circuit 30 compares the phases of the rotation detection signals separately supplied from the respective pickups 16 and 17 and calculates the phase difference. That is, for example, as shown in FIG.
The rotation detection signal from the pickup 17 (shown in FIG. 5A) is compared with the rotation detection signal from the pickup 17 (shown in FIG. 5B), and the phase difference (indicated by arrow t in the figure) is calculated. Furthermore, the phase comparison control circuit 30 determines that the value of the phase difference t is greater than or equal to a predetermined value of the rotational torque (a value at which instrumental error performance deteriorates and measurement accuracy exceeds a predetermined allowable range) as shown in FIG. When the alarm 31 becomes dry, a start signal is supplied to the alarm 31, and the alarm 31
In response, an alarm lamp (for example, an alarm lamp) lights up to notify the measuring person that the rotational torque has increased. Therefore, the measurer is informed of the increase in rotational torque by the alarm 31, and can perform maintenance on the flowmeter 1 before the instrumental error performance deteriorates or before the measurement accuracy exceeds the allowable range. As a result, the flow meter 1 can always measure the flow rate with high accuracy without deteriorating the instrumental error performance.

In addition, in FIG. 6, only one pickup 16 is used, and an amplifier 32, a counter 33, an arithmetic circuit 34, and a display 35 are connected to it. The configuration for detecting the flow rate of the fluid to be measured is shown below. In the configuration shown in FIG.
The rotation detection signal generated is amplified by an amplifier 32 and then counted by a counter 33. A count signal corresponding to the rotation of the rotating body 6 (shown in FIG. 1) is supplied to an arithmetic circuit 34, where it is converted and a flow rate signal is generated. This flow rate signal is displayed on display 3.
5, and the flow rate of the fluid to be measured is displayed here. As a result, in addition to the conventional flow rate display of the measuring section 4, a flow rate display calculated by another means such as the arithmetic circuit 34 can be obtained, so especially in flow rate measurement of a fluid to be measured where measurement reliability is required. There is profit. In other words, by looking at the difference between the two display values, it is possible to early discover failures, malfunctions, etc. in the various circuits 32 to 34 from the measuring section 4 or pickup 16 to the display 35. Reliability can be improved.

Effects of the invention As mentioned above, according to the flowmeter of the present invention, in a flowmeter equipped with a magnetic coupling,
By providing a pick-up that detects the rotation of the magnet of the magnetic coupling, the flow rate of the fluid to be measured can be determined from the rotation detection signal generated by the pick-up, and this flow rate value can be combined with the flow rate value processed by the measurement unit. By comparing, it is possible to detect malfunctions in the flowmeter at an early stage and improve the reliability of the flowmeter.Furthermore, by installing the pick-up in such a way that the rotation of each magnet in the magnetic coupling can be detected separately, Since it is possible to know the phase difference in the rotation of each magnet, and from this it is possible to estimate an increase in the rotational torque of the measuring section, the flow rate can be measured before the instrumental error performance deteriorates or the flow rate measurement accuracy deteriorates significantly. This method has the advantage that it becomes possible to perform maintenance on the flowmeter, which also improves the reliability of the flowmeter.

[Brief explanation of the drawing]

Figure 1 is an enlarged vertical cross-sectional view of a magnetic coupling provided in an embodiment of the flowmeter of the present invention, Figure 2 is a vertical cross-sectional view of the flowmeter of the present invention, and Figure 3 is a measurement Figure 4 is a block diagram showing an example of a configuration for detecting an increase in the rotational torque of the measuring section using a pick-up. Figure 5 shows an example of the phase difference that occurs between the main magnet and the driven magnet, and Figure 6 shows how to measure the flow rate of the fluid to be measured using a pick-up and the rotation of the magnet in the magnetic coupling. FIG. 2 is a block diagram showing an example of a configuration for carrying out this process. DESCRIPTION OF SYMBOLS 1... Flowmeter, 2... Flowmeter body, 3... Magnetic coupling, 4... Measuring part, 6... Rotating body, 11... Case, 12... Drive magnet, 13...
...driven magnet, 14...main driving shaft, 15...driven shaft,
16, 17... Pickup, 18... Bulkhead, 2
9, 32...Amplifier, 30...Phase comparison control circuit, 31...Alarm, 33...Counter, 34
...Arithmetic circuit, 35...Display device.

Claims (1)

[Scope of utility model registration request] A flowmeter including a magnetic coupling that transmits the rotation of a rotating body corresponding to the flow rate of the fluid to be measured to a measurement unit that measures the flow rate, and a pick-up that detects the rotation of the magnet of the magnetic coupling. A flow meter.