JPH0321453Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The invention relates to a Karman vortex generator inserted into a fluid flowing in a pipe, for example, in order to measure the intake air amount of an engine such as an automobile. The present invention relates to a Karman vortex flow meter that measures fluid flow rate using the Karman vortex street generated by the flow meter, and particularly to a fixing mechanism for a rectifying grid provided on the upstream side of a pipe of this Karman vortex flow meter.

[Prior art and its problems]

FIG. 2 shows a schematic diagram of a conventional Karman vortex flowmeter. In the figure, a Karman vortex flowmeter 1 mainly includes a pipe line 2, a Karman vortex generator 3 inserted into the pipe line 2, a Karman vortex detector 4, and a rectifying grid 5. The Karman vortex generating body 3 includes an upstream columnar body 6 formed in an isosceles triangular cross section and a downstream columnar body 7 formed in a trapezoidal cross section. Further, the Karman vortex detector 4 detects the Karman vortex street generated in the fluid flow by the Karman vortex generator 3 and measures the flow rate. In addition, the rectifier grid 5
is arranged on the upstream side of the Karman vortex generator 3 to rectify the fluid and generate a stable Karman vortex street in the Karman vortex generator 3. For this purpose, the rectifier grid 5
It consists of a number of honeycomb-like structures formed from thin aluminum foil with a thickness of about 20 μm to 50 μm. 8 is a throttle pipe installed behind the rectifying grid 5, and 9 is a bypass pipe. This rectifier grid 5
is usually a stepped portion 10 provided on the upstream side of the throttle tube 8.
The stepped portion 10 is formed by the epoxy resin material 11.
are fixed with adhesive at multiple locations. However, during a temperature test of the product, the heat shock caused cracks in the epoxy resin material 11, or flames from the engine's backup fire flowed backwards, damaging the epoxy resin material 11 and causing the rectifier grid 5 to become poorly fixed. There was a problem.

[Purpose of invention]

The present invention was devised in view of the above-mentioned conventional problems, and its purpose is to provide a simple fixing structure that can easily and reliably fix the rectifier grid to the pipe line. Our objective is to provide a Karman vortex flow meter.

[Key points of the idea]

In order to achieve this purpose, the present invention
A rectifying grid made of thin metal is provided at the upstream end of the pipe, and the rectifying grid is inserted into the pipe, and the length is equal to the length of the rectifying grid along the fluid flow direction. a first step section that is slightly longer than the first step section; a suppressing means that is disposed further upstream from the first step section and suppresses the periphery of the rectifying grid; a second stage portion provided inside the pipe on the side;
A plurality of small deformation parts are provided on the end face of the conduit further upstream of the second stage part, and the suppressing means is caulked and fixed by the small deformation parts.

[Example of idea]

Next, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 shows a schematic diagram of the main parts of an embodiment of the present invention, where A is a front sectional view, B is a side view, and C is a side view.
is an enlarged view of part A of A. In the figure, rectifier grid 5
is inserted into the first stage section 10 provided on the upstream side of the throttle tube 8, as in FIG. The second stage portion 12 is
A presser ring 13 is inserted upstream of the first stage portion 10 to hold down the rectifying grating 5 from slipping out while maintaining a small gap a, for example about 0.5 mm, between the rectifying grating 5 and the rectifying grating 5. The second step portion 12 has a larger inner diameter than the first step portion 10. Further, the presser ring fixing means includes an end surface 14 provided in the pipe line upstream from the second stage portion 12, and a plurality of small deformation portions 15, three in this embodiment, provided on this end surface 14. This small deformation portion 15 is, for example, a small deformation portion due to an impact applied to the end face 14 at the tip of a chisel. This small deformation portion 15 fixes the presser ring 13 to the second step portion 12 . By fixing the presser ring 13 in this manner, the rectifying grating 5 is easily mechanically fixed to the first step portion 10. Therefore, the fixation of the rectifying grid 5 is not affected by impacts such as heat shocks during product tests or engine backup fires, and is securely maintained.

Note that the gap a provided between the rectifying grating 5 and the holding ring 13 is provided so that the impact caused by the small deformation portion 15 applied to the holding ring 13 does not damage the rectifying grating 5. That is, the depth l of the first stage portion 10 of the pipe and the thickness t of the rectifying grid 5
is set to be l>t in terms of design, but if l<t due to manufacturing tolerances, the rectifying grid 5 made of a thin metal of several tens of micrometers may partially It will be destroyed. When the rectifying grid collapses, cracks occur in that part and the strength decreases, making it more likely to be destroyed by pressure waves such as a backup fire. Therefore, including manufacturing tolerances,
The rectifying grating 5 and the holding ring 1 are arranged so that l≧t.
3, it is possible to avoid collapse of the rectifying grid.

[Effect of idea]

As described above, according to the present invention, there is provided a first stage section in which a rectifying grid provided at the upstream end of the pipe line and for rectifying the flow of the fluid is inserted, and a further upstream side of the first stage section. a second stage section in which a presser ring is inserted that maintains a slight gap between the rectifying grid and presses the rectifying grid, and a plurality of small deformations are formed on the further upstream end surface of this second stage section. By providing a ring fixing means for fixing the presser ring to the second step part by providing a ring fixing means, the problems of the prior art are effectively solved, the structure is simple, the fixing is easy and reliable. It has the effect that

[Brief explanation of the drawing]

Figure 1 shows a schematic diagram of the main parts of an embodiment of the present invention, Figure A is a front sectional view thereof, Figure B is a side view thereof, Figure C is an enlarged view of part A of Figure A, and Figure FIG. 2 is a schematic diagram of a conventional Karman vortex flowmeter. 5: Rectifier grid, 8: Throttle tube, 10: First stage section,
12: second step part, 13: holding ring, 15: small deformation part, a: gap.

Claims (1)

[Claims for Utility Model Registration] A Karman vortex flowmeter that measures the flow rate of a fluid by using a vortex generated by a Karman vortex generator inserted into a fluid flowing in a pipe, the method comprising: a rectifying grid made of a thin metal provided at an upstream end; the rectifying grid is inserted into the inside of the pipe, and the length is slightly smaller than the length of the rectifying grid along the fluid flow direction; a very long first stage part; a restraining means disposed further upstream from the first stage part and restraining the periphery of the rectifying grid; a second step provided on the inside of the pipe; and a plurality of small deformation parts provided on an end surface of the pipe further upstream of the second step, the suppressing means being caused by the small deformation part. A Karman vortex flowmeter that is fixed by caulking.