JPH0823506B2 - Vortex flowmeter - Google Patents

Description

The present invention relates to a vortex flowmeter, and more particularly to a vortex flowmeter used in an internal combustion engine.

[Conventional technology]

Generally, when an vortex flowmeter is used in an internal combustion engine, as shown in, for example, Japanese Patent Publication No. 62-26686 and Japanese Unexamined Patent Publication No. 58-21517, the vortex flowmeter does not necessarily pollute the intake air of the engine. It was installed in the downstream of the air cleaner that removes.

By the way, if the flowmeter cannot obtain the stability of the flow of the fluid to be measured, not only the measurement accuracy will be deteriorated, but also the measurement itself will not be established. When a vortex flowmeter is used in an internal combustion engine, it is installed in the wake of the air cleaner as described above, so it is often not possible to secure a dimension that provides sufficient stability for the fluid flow. The turbulence becomes extremely large, and even when a known rectifying mechanism is used, even vortex generation may be hindered.

FIG. 3 is a cross-sectional view of a conventional vortex flowmeter installed downstream of an air cleaner of an engine. Reference numeral 1 is a vortex flowmeter, which is a quadrilateral conduit 11 through which a fluid to be measured flows and the inside of the conduit 11. And a first vortex generating column 12 for generating a Karman vortex, and a Karman vortex for generating a Karman vortex in the conduit 11 downstream of the first vortex generating column 12 The second vortex generating column 13 has, a honeycomb rectifier 14 provided on the fluid inflow side of the conduit 11, and a control circuit 15 provided outside the conduit 11. An air cleaner 2 is composed of an upstream cover 21 having a fluid inlet, a downstream cover 22 having an outlet to which the conduit 11 is connected, and a dust removing element 23 provided between the upstream cover 21 and the downstream cover 22. Reference numeral 3 is an intake pipe that is connected to the downstream side of the conduit 11 and guides the fluid to the engine through a throttle valve (not shown).

In the above configuration, the flow of the fluid to be measured, that is, the air flows from the upstream cover 21 of the air cleaner 2 along the streamline F _IN and flows in the downstream cover 22 as shown by the streamlines F _{1 to} F ₄ , and the vortex flowmeter 1
Reach the entrance. Since the fluid flows by selecting a place with a small resistance, the flow velocity is generally fastest in the streamline F ₂ , then streamlines F ₁ and F ₃ , and the slowest is the flowline F ₄ . Streamline F ₄
The flow velocity of is extremely unstable. The fluid reaching the inlet of the vortex flowmeter 1 flows out to the intake pipe 3 along the streamline F _OUT .

Next, the flow velocity distribution of the fluid flowing along the streamlines F _{1 to} F ₄ in the air cleaner 2 in the vortex flowmeter 1 will be described. FIG. 4 is a partially enlarged sectional view of the outlet side of the air cleaner 2 and the upstream side of the vortex flowmeter 1.
Is a bell mouth portion provided all around the conduit 11, and is provided downstream of the honeycomb rectifier 14. Therefore, the streamlines F _{1 to} F ₄ reaching immediately before the honeycomb rectifier 14 continue to flow in the direction indicated by the broken line, but are corrected by the honeycomb rectifier 14 and flow in the solid line direction. Next, the streamlines F ₁ and F ₃ are accelerated by the bell mouth portion 11a so as to approach the speed of the fastest streamline F ₂ . Therefore, if there is no streamline F ₄ now, the flow velocity distribution in the conduit 11 immediately before the first vortex generating column 12 will be in a relatively uniform state as shown by the solid line v _L , but in reality, Since streamline F ₄ exists, streamline F ₃ is swept away and bellmouth part
The flow velocity near 11a decreases and the flow velocity distribution becomes distorted as shown by the broken line v _L ′. The vortices generated in such a flow velocity distribution change in intensity of the vortices and sometimes disappear. This state is shown in FIG. V _C shown in FIG. 5 (a) indicates the center of the vortex column generated in the conduit 11, that is, the position of the vortex filament,
Further, V ₀ shown in FIG. 5 (b) indicates the strength of the vortex, that is, the vortex pressure. During the passage of time T from right to left, the vortex is V ₁ ~
It is assumed that ₆ of V ₆ are generated. In the vortex V ₁ , the distortion of the vortex filament is still small, but as the vortex V _{2 to} V ₄ progresses, the distortion becomes larger, and eventually the vortex filament is cut in the vortex V ₅ . During this period, the vortex strength V ₀ gradually decreases, and V ₀ becomes zero in the vortex V ₅ where the vortex filament is cut. That is, the vortex V ₅ practically does not exist. After the vortex filament is broken, a vortex V ₆ with a slightly smaller vortex strength V ₀ is generated and gradually becomes stronger. However, the vortices disappear again following the course of the vortices V _{1 to} V ₄ .

[Problems to be Solved by the Invention] As described above, in the conventional vortex flowmeter, vortices do not exist intermittently, and in a fluid with a large amount of drift or turbulence, the measurement accuracy is greatly reduced, making it unusable. There was a problem of becoming.

The present invention has been made to solve the above problems, and even for a fluid with a large amount of uneven flow or turbulence, the flow is stabilized and the vortex flow rate is capable of performing highly accurate and stable flow rate measurement. The purpose is to obtain a total.

[Means for solving the problem]

A vortex flowmeter according to the present invention is provided at a fluid inlet side end portion of a conduit, is provided with a first throttle portion that performs a fluid throttle action, and is provided downstream of the first throttle portion of the conduit, and has a flow rectifying action. And a second throttle portion provided in a conduit downstream of the rectifier and upstream of the vortex generating column and performing a fluid throttle action, and the dimensional ratio of the inlet and the outlet of the first throttle portion is 1.1 to 1.5: 1 in the direction parallel to the vortex generating column, 1.2 to 1.5: 1 in the direction perpendicular to it
Is what is.

[Work]

The first throttle portion in the present invention makes the flow velocity of the non-uniform flow close to the flow velocity of the central flow and corrects the non-uniform flow and the turbulent flow to accelerate the normal flow.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a state in which the vortex flowmeter 41 according to this embodiment is mounted on an internal combustion engine and is connected between the air cleaner 2 and the intake pipe 3. Reference numeral 11b denotes a funnel portion (first throttle portion) having a quadrangular cross section, which is provided on the upstream side of the honeycomb rectifier 14 of the conduit 11, that is, protruding into the air cleaner 2, and is similar to the bell mouth portion (second throttle portion) 11a. Is provided all around the inlet of the conduit 11. The other structure of the vortex flowmeter 41 is the same as that of the conventional vortex flowmeter 1 shown in FIG.

In the above configuration, the fluid is the same as in the conventional air cleaner 2.
Flow, but reaches the funnel portion 11b of the conduit 11, the fluid along these streamlines F ₁ to F ₃ passes through the funnel portion 11b reaches a honeycomb rectifier 14, it is corrected to the direction of flow by the honeycomb rectifier 14 , Passes through the bell mouth portion 11a. In this process, the streamline F ₁ is narrowed by the funnel portion 11b, so that the flow velocity immediately before the honeycomb rectifier 14 becomes closer to the flow velocity of the flow line F ₂ than before. Further, the streamline F ₄ has been swept away from the streamline F ₃ in the past, but is corrected in the direction in which the streamline F ₃ is accelerated by the throttling effect of the funnel portion 11b. As a result, the first vortex generating column
The flow velocity distribution v _L in the conduit 11 just before 12 becomes uniform. Therefore, as shown in FIGS. 2 (a) and 2 (b), the vortex filament position V _C and the vortex strength V _O are extremely stable and vortices are normally generated over time T, and the measurement accuracy is improved. To do. Also, the funnel section 11
Since b is provided on the entire circumference of the conduit 11, the flow velocity distribution orthogonal to the first vortex generating column 12 is also made uniform, and vortex generation is further stabilized. Here, the reduction ratio of the funnel portion 11b, that is, the dimensional ratio between the inlet and the outlet of the funnel portion 11b, is determined by
By setting 1.1 to 1.5: 1 in the parallel direction and 1.2 to 1.5: 1 in the orthogonal direction, a more stable product can be obtained.

〔The invention's effect〕

As described above, according to the present invention, the rectifier is provided on the fluid inflow side of the conduit of the vortex flowmeter, and the first rectifier is provided on the upstream side of the rectifier.
And the second throttle on the downstream side, and the dimensional ratio of the inlet to the outlet of the first throttle is 1.1 to 1.5: 1 in the direction parallel to the vortex generating column and 1.2 to 1.5 in the right angle direction. By setting the ratio to 1 :, the drift or turbulence of the fluid flowing into the vortex flowmeter is corrected by the first throttle portion, the flow velocity is increased, and the flow velocity distribution is made uniform. For this reason, the flow of the fluid is stable and the vortex is normally generated, and the flow rate measurement accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a vortex flowmeter according to the present invention connected to an air cleaner of an internal combustion engine, and FIGS. 2A and 2B are views showing vortex generation states of the vortex flowmeter according to the present invention. The figure is a cross-sectional view of a conventional vortex flowmeter connected to an air cleaner. Fig. 4 is a partially enlarged view of Fig. 3, Fig. 5 (a),
(B) is a figure which shows the vortex generation state of the conventional vortex flowmeter. 2 ... Air cleaner, 3 ... Intake pipe, 11 ... Conduit, 11a
…… Bell mouth part, 11b …… Funnel part, 12,13 …… Vortex generating column, 14 …… High cam rectifier, 41 …… Vortex flow meter. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A vortex flowmeter having a vortex generating column for generating a Karman vortex in a conduit through which a fluid to be measured passes, the first squeezing portion being formed at a fluid inflow end of the conduit and performing a squeezing action of the fluid. And downstream of the first throttle portion of the conduit,
An inlet of the first throttle portion, which includes a rectifier for rectifying the fluid and a second throttle portion formed in the conduit downstream of the rectifier and on the upstream side of the vortex generating column for performing the fluid throttle operation. And the dimension ratio of the outlet is parallel to the vortex generating column above.
A vortex flowmeter characterized by 1.1 to 1.5: 1 and 1.2 to 1.5: 1 in the right angle direction.