JPH0228410Y2 - - Google Patents

Description

[Detailed Description of the Invention] a. Field of Industrial Application The present invention relates to improvement of an electromagnetic flowmeter transmitter, and particularly to improvement of a ground ring inserted between the transmitter and a mating pipe.

b Conventional example In order to eliminate electrical noise in the fluid, an electromagnetic flowmeter transmitter has a ground ring installed above and downstream of the electromagnetic flowmeter transmitter.

Since the ground ring contains corrosive substances in the fluid, it is made of a conductive material with strong corrosion resistance, such as conductive plastic.

Figure 1 shows conductive plastic grounding ring 1.
In the plan view, reference numerals 1a, 1b, 1c, and 1d are protrusions provided on the outer periphery of the earth ring 1, which are used for fixing to a conduit and for electrical connection.

Figure 2 shows conductive plastic grounding ring 1.
FIG. 2 is a sectional view showing a state in which the electromagnetic flowmeter transmitter is attached to a conduit 2. In this figure, electrodes and magnetic field generators are omitted. Reference numeral 3 denotes an insulating sleeve that covers the inner wall of the conduit 2, and its flared portions 3a and 3b cover the flanges 2a and 2b of the conduit 2. 4a, 4
A screw c fixes the earth ring 1 to the flanges 2a and 2b, and also serves as an electrical connection between the flanges.

In such a structure, when the conduit 2 is connected to the upper or downstream mating piping (not shown), the flare portions 3a, 3b or the earth ring 1 may be damaged due to over-tightening of the bolts and nuts between the flanges of the mating piping. cracks may occur. If this happens, fluid may leak to the outside or insulation may fail.

Conventionally, as a method of preventing such over-tightening of the flange portion, a method has been known in which a protective flange is inserted between the flange 2a or 2b of the conduit 2 and the mating piping flange, as shown in Utility Model Publication No. 56-12572, for example. ing. FIG. 3 is a sectional view showing a state in which the protective flange is connected to a mating pipe.

In this figure, the same elements as in FIGS. 1 and 2 are given the same reference numerals. Note that the earth ring 1 used in this example is not provided with the protrusions 1a, 1b, . . . shown in FIG.

5 and 6, the conduit 2 is connected to the mating pipes 7 and 8 and the bolts and nuts 9, 10, 11, 12, 13, 14 and 1.
It is a protective flange to prevent over-tightening when joined with 5 and 16. This protective flange is provided with a recessed portion, and has a structure in which a tightening force exceeding a certain level is not applied to the flare portions 3a, 3b and the earth ring 1.

By the way, in the case of such a structure, the electrical connection with the grounding ring 1 is made between the concave surface of the protective flange 5 and the end face of the grounding rings 1, 1, as shown in the enlarged view of FIG. . Although the outer peripheral surface of the earth ring 1 may also come into contact with the protective flange 5, it is not reliable and the connection is mainly made at the end surface described above.

However, the earth ring 1 is usually made by mixing acicular carbon fibers and graphite with tetrafluoroethylene resin and compression molding the mixture. Therefore, during the compression molding process, the acicular carbon fibers are aligned in the radial direction of the earth ring 1, and the conductivity of the earth ring 1 is increased.
It has a characteristic that the area between the inner and outer circumference of the earth ring is larger than the end face of the earth ring.

Therefore, in order to obtain good conductivity, it is more advantageous to contact the protective flanges 5 and 6 at the outer peripheral surface of the earth ring 1 rather than at the end surface.

c. Purpose of the invention The technical problem to be solved by the invention is that in an electromagnetic flowmeter transmitter in which the conduit of the electromagnetic flowmeter transmitter and the mating pipe are joined via a metal ring to prevent over-tightening, the conduit An object of the present invention is to securely connect the conductive plastic earth ring inserted between the metal ring and the mating pipe, and to obtain good conductivity.

D. Structure of the invention In order to prevent damage to the flare part and the ground ring due to over-tightening of the flange, the structure of the invention is such that the ground The ring is press-fitted, and the grounding lead wire is pulled out from this metal ring.

E. Effect The technical means described above works as follows. That is, the outer peripheral portion of the earth ring is in close contact with the inner peripheral surface of the metal ring. Since the earth ring has high conductivity between its inner and outer peripheries, the fluid flowing in the conduit through the metal ring can be reliably grounded. The metal ring serves as an electrical connection for the ground ring, and also serves to prevent the flange from being overtightened.

F. Embodiments Examples of the present invention will be described below with reference to the drawings. FIG. 5 is a sectional view of a main part of an embodiment of the device of the present invention, FIG. 6 is a perspective view showing the relationship between a ground ring and a metal ring into which it is press-fitted, and FIG. 7 is a partially enlarged perspective view of the metal ring. be.

Components in these figures that are substantially the same as those in FIGS. 1 to 4 are given the same reference numerals, and explanations thereof will be omitted. Reference numeral 17 denotes a metal ring, the inner peripheral surface of which is knurled as shown in detail in FIG. For this reason, when the earth ring 1 is press-fitted, it meshes well with its outer circumferential surface, providing a reliable electrical connection.

The outer diameter of the flared portion 3a of the sleeve 3, which covers the flange portion 2a of the conduit 2, is selected such that its outer periphery is located inside the inner periphery of the metal ring 17.

The thickness of the metal ring 17 is set to a size that will not damage the flange 2a of the conduit 2 and the flange of the mating pipe 7 when they are tightened with bolts and nuts 9 and 10 by overlapping the earth ring 1 on the flare part 3a.

The grounding lead wire is connected directly from the metal ring 17.
Alternatively, it can be drawn out via conduit 2.

FIGS. 8a, 8b and 9 are sectional views of main parts showing other embodiments of the present invention. In FIGS. 8a and 8b, only the metal ring 18 and the ground ring 1 are shown, and in this specific example, the inner peripheral surface of the metal ring 18 is not knurled. Instead,
A stepped portion 18a constituting a locking portion and a convex portion 18b which is caulked after the earth ring 1 is press-fitted are provided on the inner edge. As shown in FIG. 8a, the grounding ring 1 is first press-fitted until it is locked by the stepped portion 18a, and then as shown in FIG.
It is confirmed. Thereby, the metal ring 18 and the earth ring 1 are reliably connected.

FIG. 9 shows still another embodiment of the present invention, in which a recess (groove) 19a is provided on the inner circumferential surface of the metal ring 19, and a convex portion is provided on the outer circumferential surface of the earth ring 1 in correspondence with this. When the earth ring 1 is press-fitted into the metal ring 19, they engage and a reliable connection is obtained.

G Effect of the invention According to the invention, the outer peripheral surface of the ground ring 1 made of conductive plastic is replaced by the metal rings 17 and 18.
Alternatively, since it can be brought into reliable contact with the inner circumferential surface of 19, extremely good conductivity can be obtained between them. Further, the metal ring acts as a stopper against over-tightening of the flange portion, thereby preventing damage to the flare portions 3a, 3b or the earth ring 1.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a grounding ring 1 made of conductive plastic, Fig. 2 is a sectional view showing the grounding ring 1 attached to a conduit 2 of an electromagnetic flowmeter transmitter, and Fig. 3 is a protective flange 5, FIG. 4 is a partially enlarged drawing of the device shown in FIG. 3, and FIG. Partial sectional view,
6 is a perspective view showing the relationship between the earth ring 1 and the metal ring 17 in the embodiment shown in FIG. 5, FIG. 7 is a partially enlarged perspective view of the metal ring 17,
FIGS. 8a, 8b and 9 are sectional views of main parts showing other embodiments of the present invention. 1...Earth ring, 2...Conduit, 2a, 2b
... Conduit flange, 3 ... Insulating sleeve, 3
a, 3b... Flare part of sleeve 3, 7, 8...
Mating piping, 17, 18, 19...metal ring.

Claims (1)

[Scope of utility model registration request] Between the flange covered with the flare part of the insulating sleeve that covers the inner wall of the conduit and the mating piping flange,
Insert a metal ring to prevent over-tightening of the flange.
An electromagnetic flowmeter transmitter in which a conductive plastic grounding ring is press-fitted into the inner circumference of this ring, and a grounding lead wire is drawn out from the metal ring.