JPH02307018A - Vortex flowmeter - Google Patents

Abstract

PURPOSE:To enable stable vortex generation and to obtain an inexpensive, high- accuracy vortex flowmeter by molding a turbulence generation body, which is provided on the entrance surface side of a straightener on the center axis of a vortex generation body in parallel to it, and a fixation member in one body. CONSTITUTION:The vortex generation column 3 arranged in a conduit 1 consists of an upstream-side vortex generation column 31 and a downstream-side vortex generation column 32. The honeycomb-shaped straightener 4 fitted to the opening part of the conduit 1 on the fluid entrance side has the fixation member 5b supported on the opening flange of the conduit 2 with rivets 6. The turbulence generation body 5a arranged on the entrance surface side of the straightener 4 on the center axis of the vortex generation column 3 in parallel to it is molded integrally with the fixation member 5b. Thus, the turbulence generation body 5a is provided on the upstream side of the vortex generation column 3, so a turbulence is generated in part of fluid and Karman vortexes which are generated on the downstream side of the vortex generation column 3 as a result are stabilized to obtain the vortexes with small fluctuations. Further, the turbulence generation body 5a is molded integrally with the fixation member 5b for supporting the straightener 4, so the number of parts is decreased and the manufacture and assembly are facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vortex flow needle used in internal combustion engines such as vehicles, and particularly for measuring fluids whose flow is highly turbulent.

[Conventional technology]

When a vortex flow meter is used in an internal combustion engine such as a vehicle, for example, Japanese Patent Application Laid-Open No. 5 El-21517 and Japanese Patent Publication No. 62-26
As disclosed in Japanese Patent No. 686, it is always installed downstream of the air cleaner of the engine. In such a configuration, there is a problem in that the stability of the fluid flow is low, so that accurate measurement from low flow rates to high flow rates cannot be performed. For this reason, for example, Japanese Patent Application Laid-Open No. 61-134620 recommends placing a turbulence generator that generates turbulence in a part of the fluid upstream of the vortex generating column to improve the stability of vortex generation. has been done.

[Problem to be solved by the invention]

However, in the above method, for example,
As described in Publication No. 67863, turbulence generators have a strong enough influence to correct the vortex frequency, that is, the flow rate characteristics that should be determined by the vortex generation column, so the vortices generated by the turbulence generators If the vortex tends to form a columnar and periodic Karman vortex, the vortex generator has a large influence on the flow characteristics, so the shape and placement accuracy of the turbulence generator must be carefully selected.

This invention was made in order to solve the above-mentioned problems, and aims to obtain a vortex flowmeter that can stably generate vortices and is inexpensive and highly accurate.

[Means to solve the problem]

The vortex flowmeter according to the present invention has a conduit through which a fluid to be measured flows, a vortex generating column that generates a Karman vortex in the conduit, a honeycomb-shaped or mesh-shaped rectifier on the inlet side of the conduit, and the rectifier. and a fixing member that supports the inlet opening of the conduit, the flow of the fluid to be measured is obstructed on the inlet surface side of the rectifier on and parallel to the central axis of the vortex generating column. The present invention is characterized in that a turbulence generator is provided, and the turbulence generator and the fixing member are integrally molded.

[Function] In this invention, by providing a turbulence generator upstream of the vortex generating column, turbulence is generated in a part of the fluid, thereby stabilizing the Karman vortex generated downstream of the vortex generating column. It is possible to obtain a vortex with little fluctuation.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
2 is a cross-sectional plan view of a vortex flowmeter according to the present invention, FIG. 2 is a front view of the vortex flowmeter viewed from the fluid inlet side, and FIG. 3 is a sectional view taken along line 11 in FIG. 1. In each figure, the vortex flow meter is designated as a whole by the reference numeral 1, and 2 is a conduit through which the fluid to be measured flows. 3
is a vortex generation column placed inside the conduit l, and the upstream vortex generation column 31
and a downstream vortex generating column 32. Reference numeral 4 denotes a honeycomb-shaped rectifier attached to the opening on the fluid inlet side of the conduit 1. The rectifier 4 has a fixing member 5b supported by a rivet 6 on the opening flange 2a of the conduit 2. Reference numeral 5a denotes a turbulence generator located on the central axis of the vortex generating column 3 on the inlet side of the rectifier 4 and arranged parallel thereto, and the turbulence generator 5a is integrated with the fixing member 5b. It is shaped like this.

Next, the operation will be explained. In Figure 1, the fluid is F
1 to F, the fluid immediately upstream of the vortex generating column 3 in the main pipe l is f7. r zl.

The flow becomes as shown in Ext and Is, and a Karman vortex V is generated in the wake of the vortex generating column 3. Here, if there is no turbulence generator 5a, the fluid rt shown by the broken line is the fluid r.

If the turbulence generator 5a is present, turbulence will occur in the fluid F immediately after the turbulence generator 5a. The region surrounded by the fluid '11+f12 is a turbulent region.

It is well known that Karman vortices are likely to occur when there is turbulence in the fluid colliding with the vortex generating column 3.

Here, the turbulent flow state of the above-mentioned turbulent region E will be explained.

The vortices downstream of the turbulent flow generator 5a have a turbulent shape in a cross section perpendicular to the flow. Moreover, the vortex is a so-called Karman vortex. However, since the flow is divided in the perpendicular cross-sectional direction by the rectifier 4 immediately after the turbulent flow generator 5a, the groove column is collapsed as is clear from the flow velocity distribution shown by Vtg shown in FIG. Therefore, within the turbulent region E, turbulence occurs in both directions parallel to and perpendicular to the flow. Therefore, the turbulent flow generated by the turbulence generating body 5a only serves as a triggering factor for the generation of Karman vortices in the vortex generating column 3, and does not greatly affect the Karman vortex generation period of the vortex generating column 3. Even if the width dimension d of the flow generator 5a changes slightly, the Karman vortex generation period determined by the vortex generation column 3 is not disturbed.
There is no need to improve the dimensional accuracy of the turbulent flow generator 5a.

Here, the dimension d of the turbulence generating body 5a and the vortex generating column 3 are shown in FIG.
In this figure, the solid line shows d/D and fluctuation severity according to the present invention, and the broken line shows the fluctuation rate according to the conventional device.

Figure 5 (al~) shows various cross-sectional shapes of the turbulence generating body 5a, as shown in Figure (a), a rectangular shape is most likely to cause turbulence in the fluid. However, since the pressure loss of the fluid is large, (b) ~ (d
) As shown in the figure, it is preferable to form convex portions of respective shapes on the upstream surface of the turbulent flow generating body 5a because the pressure loss can be reduced.

Furthermore, as described above, by integrally molding the turbulence generator 5a and the fixing member 5b that supports the rectifier 4, the support member for the turbulence generator 5a is not required, and the number of assembly steps is reduced accordingly. There is no need to prepare a special member as the flow generator 5a.

In the embodiment, an example in which a honeycomb-shaped rectifier 4.7 is used has been described, but the same effect as described above can be obtained even if a mesh-shaped rectifier is used.

〔Effect of the invention〕

As explained above, according to the present invention, the Since the turbulence generator is placed on the inlet side of the rectifier upstream of the vortex generating column, the flow characteristics are not significantly affected by the dimensional accuracy of the turbulence generator, and moreover, The result is a highly accurate and inexpensive vortex flowmeter that exhibits little vortex fluctuation even when there is turbulence. Furthermore, since the upstream turbulence generator is integrally molded with the fixing member for supporting the rectifier, the number of parts can be reduced and manufacturing and assembly can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional plan view of a vortex flowmeter according to an embodiment of the present invention, FIG. 2 is a front view of the vortex flowmeter seen from the fluid inlet side,
Figure 3 is a sectional view taken along the line 11 in Figure 1, Figure 4 is a characteristic diagram of the 13 lag factor of the vortex, and Figures 5 (a) to (d) are various examples of the cross-sectional shape of the turbulence generator. FIG. 2... Conduit, 3... Vortex generating column, 4... Rectifier, 5
a... Turbulent flow generator, 5b... Fixing member. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] It has a conduit through which the fluid to be measured flows, a vortex generation column that generates a Karman vortex in the conduit, a honeycomb-shaped or wire-shaped rectifier on the inlet side of the conduit, and this rectifier supported at the inlet opening of the conduit. In the vortex flowmeter, a turbulence generator is provided on the inlet surface side of the rectifier on the central axis of the vortex generating column and parallel to the central axis to obstruct the flow of the fluid to be measured. A vortex flowmeter characterized in that a turbulent flow generator and the fixing member are integrally molded.