JPH02138827A - Mass flowmeter - Google Patents

Abstract

PURPOSE:To minimize errors with the apparatus made compact as a whole by mounting a sensor section on a flowmeter body connected to a fluid conveying tube in such a manner as to remove freely while a laminar flow element with a straight and slender passage is used at a bias section. CONSTITUTION:Based on a flow rate ratio between a sensor section 7 and a bypass section 9, a total flow rate of a fluid can be measured from a flow rate detected at the sensor section 7. Then, when a clogging occurs in the sensor section 7 or the bypass section 9 due to impurities in the fluid, a reaction of the fluid and the like, with a lower body 1B left connected to conveying tubes 2 and 3, the sensor section 7 and the bypass section 9 can be removed together simply thereby facilitating the maintenance thereof. Moreover, as a part connected directly to passages 4 and 5 at the sensor section 7 and the bypass section 9 can be formed free from a connecting section of the conveying tubes 2 and 3, a passage for the connecting section of the conveying tubes 2 and 3 is set at the minimum necessary thereby achieving a excellent responsiveness with a quick replacement of the fluid when different kinds of fluids are measured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides mutual benefits when fluid is divided into a flow rate detection sensor section using a capillary tube and a bypass section using a laminar flow element, and the flow rate ratio between the sensor section and the bypass section is improved. The present invention relates to a mass flow meter configured to measure the total flow rate of fluid based on.

In the above mass flow meter, conventionally, as shown in FIG.
For example, a laminar flow element 24 configured by laminating a large number of disks having grooves along the flow path direction may be provided to
At the same time, a flow rate detection sensor 27 using a capillary tube 26 is removably connected in parallel to the bypass section 25, and the flow meter main body 22 is connected to a fluid transport pipe on the artificial side and the outlet side of the fluid. 28 and 29 through joints 30 and 30 such as unions.

However, in a mass flow meter, the sensor section 27
The capillary tube 26 and the laminar flow element 24 of the bypass section 25 may be clogged by impurities in the fluid, or the capillary tube 26 or the laminar flow element 24 may become clogged due to reaction with the fluid. It is possible to easily clear the blockage or replace the sensor section itself, but in the bypass section 25, it is necessary to remove the entire device from the joint 30.30 of the transport pipe 28.29. figure,
Not only was maintenance very poor, but the flow meter itself had to be replaced even when it did not need to be replaced, which was disadvantageous in terms of cost.

Separately, since the bypass section 25 is constructed in the flow path 23 itself that connects the fluid transport pipes 28 and 29, a large dead space is formed before and after the bypass section 25, and therefore, different fluids are When used as a measurement target, it took time to replace the fluid and lacked responsiveness.

In view of the above circumstances, the present invention provides a mass flow rate that is useful in terms of use, making it possible to improve maintenance and quickly replace the fluid when changing the measurement target by making a very quick modification. The purpose is to provide a measurement system.

Embodiments of the present invention will be described below with reference to the drawings.

In the mass flow meter shown in FIG. 2, reference numeral 1 denotes a flow meter body, which is formed in or inside the flow channels 4 and 5 connecting the fluid transport pipe 2 on the inlet side and the fluid transport pipe 3 on the outlet side. Across the channels 4 and 5, a flow rate detection sensor section 7 using a capillary tube 6 and a bypass section 9 using a laminar flow element 8 are connected in parallel.

Said? [The jt meter main body 1 is divided into an upper flowmeter main body IA in which the sensor section 7 and the bypass section 9 are connected in parallel, and a lower flowmeter main body IB in which the fluid transport pipes 2 and 3 are connected. Q-IJ song 0 around channels 4 and 5,
10, connect the upper and lower main bodies IA and IB to port 1-1.
1.11, it is airtightly connected.

As shown in FIG. 2, the sensor section 7 includes a capillary tube 6 bent in a U-shape, which is fixed to the upper main body IA with both ends communicating with the flow channels 4 and 5. The capillary tube 6 and the two sensor coils 12 and 13 wound around it are entirely buried in a heat insulating material 14 such as closed polystyrene foam so as to be unaffected by the ambient temperature as much as possible. The flow shield measurement principle is based on the fact that the degree to which the sensor coil 12 , 13 is cooled is proportional to the mass flow rate of the fluid flowing through the capillary tube 6 .

That is, the two sensor coils 12 and 131k constitute a bridge circuit together with two resistance elements (not shown).
This bridge circuit is configured so that the sensor coil 12.13 is cooled by the flow of fluid and generates an unbalanced voltage due to the resistance value of the sensor coil 12.13 that changes accordingly. 7
The flow rate of the fluid flowing through can be measured based on this unbalanced 11 pressure.

In FIG. 2, 15... are terminals at both ends of the sensor coils 12, 13. To connect this terminal 15... to an external circuit, it can be done via the lead wire 16 wrapped around the terminal 15, as shown in Figure 4 (A), or via the lead wire 16 wrapped around the terminal 15, as shown in Figure 4 (B). Alternatively, a copper foil 17 electrically connected to the terminals 15 is formed on the back surface of the upper main body IA, and this can be carried out through the upper main body IA.

The bypass section 9, as shown in FIGS. 2 and 3,
It consists of a plurality of capillaries forming the laminar flow element 8 and a U-shaped member 18 containing these capillaries,
The channel 4, through the hole 19.20 formed in the upper body IA.
5 and is fixed to the upper main body IA in a state in which the sensor part 7 is built in a recess corresponding to the U-shaped space of the sensor part 7 formed in the heat insulating material 14.

As the laminar flow element 8 of this bypass section 9, the sensor section 7
It is most preferable to use a capillary tube with the same characteristics as the capillary tube 6 used in the sensor section 7, but it is sufficient if the characteristics are similar to those of the capillary tube 6 of the sensor section 7. Those with a structure in which multiple layers are arranged facing in the direction of the flow path, and furthermore, those with a thin circular plate of 0.3 m, etc., with countless extremely small holes of about 0.3 to 1 Qum in diameter. A pore filter or the like may also be used.

According to the above configuration, the total flow rate of the fluid can be measured from the flow rate detected by the sensor unit 7 based on the flow rate ratio in the sensor unit 7 and the bypass unit 9, and the total flow rate of the fluid can be measured from the flow rate detected by the sensor unit 7. 7 or the bypass section 9,
If a blockage occurs due to impurities in the fluid or reaction of the fluid, the sensor section 7 and the bypass section 9 should be integrally removed with the upper body IA for 1 ml while the lower body IB is connected to the transport w2 and 3. They can be removed and maintenance can be done easily.

Furthermore, since the direct communication portion of the sensor section 7 and the bypass section 9 with the flow path 4.5 can be formed independently of the communication section of the transport pipe 2.3, the The flow path in the communication part can be set to the minimum necessary,
In other words, the dead space in the flow path can be reduced, fluid replacement can be quickly performed when different types of fluids are measured, and responsiveness is excellent.

Historically, by incorporating the bypass section 9 into the U-shaped space of the sensor section 7, the entire flowmeter can be constructed compactly, and by locating both sections 7 and 9 in the same room, the environment can be reduced. This has the advantage that both 7 and 9 can easily respond simultaneously to changes in the flow rate, and the flow rate error can be reduced.

FIG. 5 shows a first modified structure of the present invention. This thing is
The sensor section 7 and the bypass section 9 are assembled into a unit and detachably attached to the lower body IB, and the bypass section 9 is further detachably connected to the upper body IA by bolts, and the connecting section includes a bolt. An O-ring 21 is attached, and the sensor section 7 or bypass section 9 can be replaced separately, making it highly economical.

Figure 9J6 shows a second modified structure, in which the sensor section 7 and the bypass section 9 are arranged side by side on a single substrate 22, and the sensor section 7 and the bypass section 9 are arranged in the flow channels 4 and 5, respectively. The board 22 is detachably bolted to the flow meter main body 1 in a parallel connection state.

As described above in detail in the embodiments, the present invention has a sensor section and a bypass section that are integrally detachably attached to the main body of the flowmeter while the fluid transport pipe remains connected to the main body of the flowmeter. This makes it easy to maintain and eliminate blockages in the sensor and bypass sections, and to replace them.Moreover, the communication section of the sensor section and bypass section with the flow path is formed in a position that is unrelated to the communication section of the fluid transport pipe with the flow meter main body. Therefore, the diameter of the stream in the communicating part of the transport pipe can be made small, that is, the dead space before and after the sensor part and the bypass part can be made small, making it possible to measure different types of fluids. Fluid replacement can be performed quickly when
Furthermore, as explained in the embodiment, when the bypass section is built into the U-shaped space of the sensor section, not only does the entire device become more compact, but the sensor section and the bypass section simultaneously respond to changes in the environment. This has advantages such as easier response and, as a result, smaller errors.

[Brief explanation of the drawing]

Fig. 1 shows the conventional structure (1 side view); Fig. 2 and subsequent figures show the embodiments of the present invention; Fig. 2 is a broken side view; A) and (B) are views showing each side of the lead wire for connecting the terminal of the sensor coil and an external circuit, and FIGS. 5 and 6 are a vertical cross-sectional view 1 and a perspective view 1 of the modified structure, respectively. 1...Flow meter body, 2, 3...Fluid transport pipe, 6...
・Capillary tube, 7... Sensor part, 8... Laminar flow element, 9
...Bypass section.

Claims (2)

[Claims] (1) Dividing the fluid into a flow rate detection sensor section using a capillary tube and a bypass section using a laminar flow element, and measuring the total flow rate of the fluid based on the flow rate ratio of the sensor section and the bypass section. A mass flow meter configured to have at least the sensor section removably attached to a flow meter body connected to a fluid transport pipe, and further having a straight and elongated flow path as a laminar flow element in the bypass section. A mass flow meter characterized by using. (2) The mass flow meter according to claim (1), wherein a capillary tube having the same or almost the same characteristics as the capillary tube in the sensor section is used as the laminar flow element in the bypass section.