JPH045928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a fluid introduced from a fluid inlet is divided into a bypass part and a sensor part using a capillary tube, and then led out from a fluid outlet, and the fluid is divided into a bypass part and a sensor part using a capillary tube. The present invention relates to a mass flow meter configured to measure the total flow rate of a fluid based on a flow rate ratio.

In order to accurately measure the flow rate in this type of flowmeter, the ratio of the fluid flow rate flowing through the sensor section and the fluid flow rate flowing through the bypass section must be kept constant.

This type of flowmeter uses a method of calculating the total flow rate of the fluid from the detected value at the sensor section and the flow rate ratio between the sensor section and the bypass section, so if the ratio changes, a large measurement error will occur. It is from.

Furthermore, based on the above measurement principle, if the sensor section becomes clogged, it will directly lead to a large measurement error, so maintenance such as cleaning and replacement of the sensor section is particularly important.

In order to solve this problem, as a fluid resistance element of the bypass section, for example, US Patent Specification No.
3851526, which has a laminated structure of many disks with a hole in the center of each disk and grooves in the radial direction, or JP-A-122148-1
Although there is a sensor using an orifice as shown in the above publication, satisfactory results have not been obtained because the structure is essentially different from a sensor section formed by a capillary tube. Furthermore, although there are examples in which a capillary tube is used as a fluid resistance element in a bypass section, insufficient consideration is given to the maintenance of the sensor section and the like.

An object of the present invention is to provide a mass flow meter that solves the above problems.

In order to achieve the above object, the present invention divides the fluid introduced from the fluid inlet into the bypass part and the sensor part, and then leads it out from the fluid outlet, and based on the flow rate ratio of the bypass part and the sensor part. In the mass flow meter configured to measure the total flow rate of a fluid, the sensor portion uses a capillary tube, the bypass portion is formed by incorporating a plurality of capillary tubes in a member having a circular longitudinal section, and further includes: A portion of the capillary tube of the sensor section around which the sensor coil is wound is arranged approximately parallel to the capillary tube of the bypass section, and the lower block equipped with the fluid inlet and the fluid outlet port and the upper block equipped with the sensor section. The upper block can be detached from the lower block.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows that the fluid introduced from the fluid inlet 4 is divided into a bypass part 9 and a sensor part 7 using a capillary tube 6, and then led out from the fluid outlet 5. A mass flow meter configured to measure the total flow rate of fluid based on the flow rate ratio of is shown.

The fluid inlet 4 and fluid outlet 5 are formed in the lower block 1B, and fluid transport pipes 2 and 3 are connected to them as shown.

1A is an upper block to which the sensor part 7 and the bypass part 9 are attached, and the bolt 1
1 and 11, it can be attached to and detached from the lower block 1B. Incidentally, the bypass portion 9 may be provided on the lower block 1B side.

10, 10 are upper block 1A and lower block 1B
This is an O-ring installed between the The sensor section 7 has a capillary tube 6 bent in a U-shape fixed through the upper block 1A with both ends communicating with the fluid inlet port 4 and the fluid outlet port 5, and also connects the capillary tube 6 and the capillary tube 6 to the upper block 1A. The two installed sensor coils 12 and 13 are embedded in a heat insulating material 14 such as closed polystyrene foam so as to be unaffected by ambient temperature as much as possible. Incidentally, the capillary tube 6 of the sensor section may be straight without being bent. The flow rate measurement principle in this sensor section 7 is as follows:
It is based on the fact that the degree to which the sensor coils 12, 13 are cooled is proportional to the mass flow rate of the fluid flowing through the capillary tube 6.

15... are terminals at both ends of the sensor coils 12, 13. The terminals 15 can be connected to an external circuit through the lead wires 16 wrapped around the terminals 15, as shown in FIG. 3A, or via the upper block 1, as shown in FIG. 3B.
Copper foil 17 connected to terminal 15 on the back side of A
can be formed and then via block 1A.

As shown in FIGS. 1 and 2, the bypass section 9 includes a plurality of capillary tubes 8 and a member that houses these capillary tubes and has a substantially U-shape in side view and a circular vertical cross section. 18, and communicates with the fluid inlet 4 and fluid outlet 5 through the holes 19 and 20 formed in the upper block 1A, and the U-shaped space of the sensor section 7 formed in the heat insulating material 14. It is fixed to the upper block 1A in a built-in state.

The portion of the sensor capillary tube 6 around which the sensor coils 12 and 13 are wound and the bypass capillary tube 8 are arranged substantially parallel to each other, as shown in FIG. In this embodiment, as shown in FIG. 2, the entire interior of the member 18 is filled with the capillary tube 8, but the present invention is not limited to this. A bypass portion may be formed by storing the capillary tube 8 inside and inserting the capillary tube 8 into the gap formed between the closing body and the inner peripheral surface of the member 18.

According to the above embodiment, 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. When the section 7 becomes clogged due to impurities in the fluid or reaction of the fluid, the upper block 1B should be removed while the lower block 1B remains connected to the transport pipes 2 and 3.
It can be easily removed together with A, and maintenance of the sensor section 7 such as cleaning and replacing the capillary tube 6 can be easily performed.

FIG. 4 shows another embodiment of the present invention. This unit consists of the sensor section 7 and the bypass section 9 which are detachably attached to the lower block 1B, and the bypass section 9 is detachably connected to the upper block 1A with bolts, and the connecting section is connected to the bypass section 9. is equipped with an O-ring 21, and the sensor section 7 or the bypass section 9 can be particularly replaced, making it highly economical.

The present invention has the above-mentioned configuration, and after dividing the fluid introduced from the fluid inlet into the bypass section and the sensor section, the fluid is led out from the fluid outlet, and the fluid is In a mass flow meter configured to measure the total flow rate, a capillary tube is used not only in the sensor section but also in the bypass section, so that the ratio of the fluid flow rate flowing through the sensor section and the fluid flow rate flowing through the bypass section is kept constant. Furthermore, since the part of the sensor capillary around which the sensor coil is wound, which performs the main function of the sensor part, and the capillary of the bypass part are arranged approximately parallel to each other, the capillary in both parts is It is easy to make the installation conditions almost the same, so external factors such as ambient temperature or installation direction (whether the mass flow meter is installed vertically or horizontally, etc.) can be easily maintained. This makes it possible to make the degree of environmental influence on the capillary tubes in both parts almost the same, thereby reducing errors caused by the external environment. Separated into an upper block equipped with a sensor section,
Since the upper block is detachable from the lower block, it is easy to clean and replace the sensor capillary tube, which requires the most maintenance such as clearing blockages in order to maintain measurement accuracy.

[Brief explanation of drawings]

FIG. 1 is a cutaway side view showing one embodiment of the present invention;
Figure 2 is a sectional view of the bypass section, Figures 3A and B are diagrams showing examples of lead wire extraction for connecting the terminal of the sensor coil and an external circuit, and Figure 4 is another embodiment of the present invention. FIG. 1A...Upper block, 1B...Lower block, 4
...Fluid inlet, 5...Fluid outlet, 6...Capillary tube, 7...Sensor section, 8...Capillary tube, 9...Bypass section, 12, 13...Sensor coil, 18
...A member with a circular longitudinal section.

Claims (1)

[Claims] 1 The fluid introduced from the fluid inlet is divided into the bypass part and the sensor part, and then led out from the fluid outlet, and the total flow rate of the fluid is measured based on the flow rate ratio of the bypass part and the sensor part. In the mass flow flowmeter, a capillary tube is used in the sensor section, the bypass section is formed by incorporating a plurality of capillary tubes in a member having a circular longitudinal section, and a sensor coil of the capillary tube of the sensor section is further wound. and the capillary tube of the bypass section are arranged approximately parallel to each other, and the upper block is divided into a lower block equipped with the fluid inlet and the fluid outlet and an upper block equipped with the sensor section, and the upper block is attached to and detached from the lower block. A flexible mass flow meter.