JP4934451B2 - Bourdon tube mounting structure, pressure gauge, and bourdon tube mounting method - Google Patents

Description

  The present invention relates to a structure for attaching a Bourdon tube to a joint, a pressure gauge provided with this structure, and a method for attaching a Bourdon tube to a joint.

Some pressure gauges and other measuring instruments use Bourdon tubes. In the measuring instrument using this Bourdon tube, the case is fixed to the joint, the base end of the Bourdon tube is attached to this joint, and the pointer is connected to the tip of this Bourdon tube, so that the pressure introduced at the joint is introduced. There is a type of pressure gauge in which the pointer is rotated by the pressure introduced from the hole.
In this type of pressure gauge, a structure is known in which a base end portion of a Bourdon tube is formed in a joint and is inserted into a mounting hole communicated with a pressure insertion hole, and the base end portion of the Bourdon tube is brazed to the joint. (Non-Patent Document 1).
In brazing the Bourdon tube to the joint, conventionally, the base end of the Bourdon tube is inserted into the mounting hole formed larger than the pressure introduction hole, and the base end of the Bourdon tube is abutted against the bottom surface of the mounting hole. Thereafter, the joint is heated, so that the molten brazing material flows between the attachment hole and the base end portion of the Bourdon tube from the joint outer surface side toward the attachment hole bottom surface.

Industrial Measurement Technology University 4 “Pressure / Vacuum Level Measurement” pp. 62-63 (issued by Nikkan Kogyo Shimbun, May 31, 1965)

In the conventional example, the Bourdon tube has a base end opening formed orthogonal to the tube axis. Therefore, in a state where the base end portion of the Bourdon tube is in contact with the bottom surface of the mounting hole, the base end opening of the Bourdon tube is in contact with the bottom surface of the mounting hole over substantially the entire surface.
In this state, even if the joint is heated to allow the brazing material to flow from the joint outer surface side into the attachment hole, the air accumulated in the space between the attachment hole and the base end of the Bourdon tube is difficult to escape. . Further, the temperature distribution is not uniform in the vicinity of the joint attachment hole due to the difference in thickness, and the melting of the brazing material differs from part to part, resulting in a poor brazing material flow.
For this reason, the conventional example has a problem that the molten brazing material cannot sufficiently reach the depth of the mounting hole, voids are generated inside the brazing material, and the adhesive strength of the brazing material is reduced.

  An object of the present invention is to provide a Bourdon tube mounting structure, a pressure gauge, and a Bourdon tube mounting method capable of sufficiently brazing the base end portion of a Bourdon tube to a mounting hole of a joint.

In the Bourdon tube mounting structure of the present invention, the base end of the Bourdon tube is inserted into a mounting hole formed in a joint, and a brazing material is caused to flow between the base end of the inserted Bourdon tube and the mounting hole. A mounting structure for a Bourdon tube to be brazed, and an air discharge path for discharging air accumulated in the mounting hole when a brazing material enters between the mounting hole and a base end portion of the Bourdon tube. Formed at the base end of the Bourdon tube, the mounting hole is formed with a bottom surface against which the base end of the Bourdon tube abuts, and the air discharge path is a notch formed at the base end of the Bourdon tube It is characterized by.

Mounting Bourdon tube of the present invention, insert the the mounting hole bottom is formed to the rear end of the bourdon tube abuts the bourdon tube, the base end portion of the Bourdon tube plugged the heating the adoptive hand A method for mounting a Bourdon tube in which a brazing material is caused to flow between the mounting holes and brazing, wherein a notch air discharge passage is formed in advance at the base end of the Bourdon tube, and the joint is heated. Thus, when the molten brazing material enters between the mounting hole and the base end of the Bourdon tube, the air accumulated in the mounting hole is discharged through the air discharge path. .

In the invention with the above configuration, the proximal end portion of the Bourdon tube is inserted into the fitting attachment hole, and the vicinity of the position where the fitting attachment hole is formed is heated with the brazing material disposed in the vicinity of the fitting attachment hole. The molten brazing material is caused to flow between the mounting hole and the base end portion of the Bourdon tube. When the molten brazing material flows toward the back of the mounting hole, the air accumulated in the mounting hole is discharged to the outside through the air discharge path, and the molten brazing material reaches the base end of the Bourdon tube sufficiently. Become.
In the present invention, brazing is used in a broad concept including soldering and silver brazing.
Accordingly, in the present invention, since an air discharge passage in the rear end of the bourdon tube, also flows into the brazing material melted for brazing to the mounting hole, the air accumulated inside the mounting hole air outlet It is less likely that voids are generated inside the brazing material because the molten brazing material discharged to the outside through the passage reaches the entire base end of the Bourdon tube. Therefore, it is possible to sufficiently perform brazing in which the adhesive strength of the brazing material is ensured more than ever.

Moreover, the mounting hole is formed a bottom surface of the base end portion of the Bourdon tube abuts, since the air discharge passage is configured as a notch formed at the base end of the Bourdon tube, the bourdon the air discharge passage Since it can be formed simply by cutting the base end of the tube into a predetermined shape, the air discharge path can be formed at low cost.

Furthermore, it is preferable that the notch is formed so as to cross obliquely at an angle of more than 0 ° and less than 90 ° with respect to a plane orthogonal to the axis of the base end portion of the Bourdon tube.
In the present invention having this configuration, the air discharge path can be formed simply by obliquely cutting the base end portion of the Bourdon tube having the same structure as the conventional one with an appropriate means such as a cutting machine. And it can form easily.

The Bourdon tube is preferably a helical type Bourdon tube.
The aforementioned Bourdon tube mounting structure is preferably used for a pressure gauge. In this case, the end of the Bourdon tube is connected to the pointer.
In this invention of this structure, the pressure gauge which can achieve the above-mentioned effect can be provided.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing an internal structure of a pressure gauge according to the present embodiment, and FIG. 2 is a side view showing the internal structure.
In these drawings, a pressure gauge includes a joint 1 attached to a pipe or the like (not shown), a bottomed cylindrical case 2 fixed to the joint 1, and a helical bourdon whose base end is fixed to the joint 1. The structure includes a tube 3, a scale plate 4 attached to the front surface of the case 2, and a cover 5 fitted to the scale plate 4 and the outer peripheral portion on the front side of the case 2.

The structure of the joint 1 is shown in FIGS. FIG. 3A is a front view of the joint 1, and FIG. 3B is a side view of the joint 1.
3A and 3B, the joint 1 includes a screw portion 11 provided at one end portion, a substantially rectangular parallelepiped main body portion 12 formed integrally with the screw portion 11, and one end of the main body portion 12. It has a standing part 13 formed on the part side, and is a structure formed integrally with a metal member such as brass, stainless steel, or steel.

Inside the joint 1, a pressure introduction hole 1 </ b> A for introducing a fluid to be measured and a mounting hole 1 </ b> B for attaching a base end portion of the Bourdon tube 3 are formed continuously.
The pressure introduction hole 1A includes a first flow path 1A1 formed in the middle of the main body 12 from the end surface of the screw section 11 along the axial center of the screw section 11, and an upright section 13 from the tip of the first flow path 1A1. A second flow path 1A2 formed by bending toward the side, and a third flow path 1A3 formed by bending from the front end portion of the second flow path 1A2 toward the side surface of the upright portion 13 at a right angle. . The third flow path 1A3 communicates with the mounting hole 1B, and the mounting hole 1B is opened on the side surface of the upright portion 13. The second flow path 1A2 is sealed at the end of the joint 1.
The third flow path 1A3 and the attachment hole 1B are formed coaxially, and the diameter of the third flow path 1A3 is smaller than the diameter of the attachment hole 1B. Therefore, an annular bottom surface 1B1 is formed at the end of the mounting hole 1B on the third flow path 1A3 side.

Returning to FIG. 1 and FIG. 2, the case 2 includes a disc portion 21 and a cylindrical portion 22 provided on the outer peripheral edge of the disc portion 21, and is integrally formed from a metal member made of iron or stainless steel. It is a structure. The central portion of the disc portion 21 is fixed to the outer peripheral portion of the joint 1 with a screw.
The Bourdon tube 3 is connected to a pointer 7 via an internal enlarging mechanism 6.
The internal enlarging mechanism 6 enlarges the amount of displacement of the tip of the Bourdon tube 3 and transmits it to the pointer 7, and a mounting plate 61 attached to the front surface of the upright portion 13 of the joint 1 via a screw 6 </ b>A; A rod 62 having one end rotatably attached to the tip of the Bourdon tube 3, a sector gear 63 having a part rotatably attached to the other end of the rod 62 and a rotating shaft provided on the attachment plate 61; A pinion 64 meshed with the sector gear 63 and fixed with the pointer 7 coaxially is provided.

The pointer 7 includes a pointer main body 71 and a shaft portion 72 that is fixed to the base end portion of the pointer main body 71 and passes through the center portion of the scale plate 4 and to which the pinion 64 is fixed.
The scale plate 4 is fixed to the mounting plate 61.
The cover 5 includes a cover main body 51 that fits into the cylindrical portion 22 of the case 2, and a disk-like window member 52 provided on the cover main body 51, and the window member 52 is spaced from the scale plate 4 by a predetermined distance. They are spaced apart from each other.
An annular packing 53 is interposed between the window member 52 and the opening end surface of the case 2.

4A to 4D show a specific configuration of the Bourdon tube 3. 4A is a bottom view of the Bourdon tube 3, FIG. 4B is a cross-sectional view taken along line BB in FIG. 4A, and FIG. 4C is a front view of the Bourdon tube 3. 4 (D) is a side view of the Bourdon tube 3.
In these drawings, the Bourdon tube 3 is formed integrally with a proximal end portion 31 called a stock portion, a spiral portion 32 formed integrally with the proximal end portion 31 and having an elliptical cross section, and a distal end portion of the spiral portion 32. It is metal parts, such as beryllium copper, brass, phosphor bronze, stainless steel, and special steel, provided with the tip portion 33 (tube tip). The distal end portion 33 is sealed and connected to the rod 62. When the fluid to be measured is introduced from the opening of the proximal end portion 31 of the Bourdon tube 3, the distal end portion 33 is rotated by the pressure.

The attachment structure of the base end portion 31 of the Bourdon tube 3 to the joint 1 is shown in FIG.
In FIG. 5, the base end portion 31 of the Bourdon tube 3 is inserted into the attachment hole 1 </ b> B of the joint 1. The axial centers of the base end portion 31 and the mounting hole 1B are on substantially the same axis. The opening end side of the mounting hole 1B is tapered.
A brazing material 8 is filled between the mounting hole 1 </ b> B and the outer peripheral surface of the base end portion 31.
The open end of the base end portion 31 is cut away at an angle α with respect to a plane Q perpendicular to the axis C of the axis, and the notch 9 is an air discharge path of the present embodiment. It is said. In forming the notch 9, the base end portion 31 of the Bourdon tube 3 having the same structure as the conventional one is cut by an appropriate means such as a cutting machine.
Here, the angle α is 15 °. In the present embodiment, the angle α is not limited to 15 °, and may be an angle exceeding 0 ° and less than 90 °. When α is close to 0 °, there is an inconvenience that the function as an air discharge path cannot be sufficiently performed. When the angle is close to 90 °, the length of the base end portion 31 becomes long, so that the attachment hole 1B of the joint 1 has to be provided long, that is, there is an inconvenience that the bonding area must be secured.

Next, a method for attaching the Bourdon tube 3 of the pressure gauge of the present embodiment to the joint 1 will be described with reference to FIGS.
First, as shown in FIG. 6 (A), the attachment hole 1B and the pressure introduction hole 1A are formed in the joint 1, and as shown in FIG. 6 (B), on the opening side surface of the attachment hole 1B of the joint 1. A ring-shaped brazing material 8 is arranged.
Then, as shown in FIG. 6C, the base end portion 31 of the Bourdon tube 3 in which the notch 9 is formed in advance on the opening end side is inserted into the brazing material 8 and the mounting hole 1B, and the base end portion 31 is opened. Insert until the end hits the bottom surface 1B1. Thereby, since the maximum adhesion area can be ensured, stable adhesion strength can be obtained by abutting.

In this state, as shown in FIG. 6D, the vicinity of the attachment hole 1B of the joint 1 is heated. Then, as shown in FIG. 6 (E), the heat of the joint 1 is transmitted to the brazing material 8 and the brazing material 8 is melted. The melted brazing material 8 is connected to the proximal end portion 31 of the inserted Bourdon tube 3. It flows in between the attachment holes 1B.
When the brazing material 8 tries to flow into the mounting hole 1B, the air accumulated in the mounting hole 1B wraps around the opening edge through the notch 9 formed at the distal end portion of the base end portion 31.
Here, since the tip 33 of the Bourdon tube 3 is sealed, the air purged by the molten brazing material 8 is sent to the pressure introducing hole 1A as indicated by the arrow P. This air is discharged to the outside of the joint 1 through the third flow path 1A3, the second flow path 1A2 and the first flow path 1A1 of the pressure introduction hole 1A.

Therefore, in this embodiment, the following effects can be achieved.
(1) Since the notch 9 is formed in the base end portion 31 of the Bourdon tube 3 as an air discharge path for discharging the air accumulated in the mounting hole 1B, the Bourdon tube 3 is brazed to the joint 1 Even if the molten brazing material 8 flows between the mounting hole 1B formed in the joint 1 and the Bourdon tube 3, the air accumulated in the mounting hole 1B is exposed to the outside through the notch 9 and the pressure introducing hole 1A. As a result, the molten brazing material 8 reaches the entire base end of the Bourdon tube 3. Therefore, the adhesive strength of the brazing material 8 is improved more than ever and brazing can be performed sufficiently.

(2) Since the notch 9 can be formed simply by cutting the base end portion 31 of the Bourdon tube 3 into a predetermined shape, the air discharge path can be formed at low cost.

(3) The notch 9 is formed so as to cross obliquely at an angle of 15 ° with respect to a plane orthogonal to the axis of the base end portion 31 of the Bourdon tube 3. Therefore, the notch 9 can be formed only by obliquely cutting the base end portion 31 of the Bourdon tube 3, so that the air discharge path can be formed at a lower cost.
(4) Since the tapered portion is formed on the opening end side of the mounting hole 1B, a large space is formed between the tapered portion and the base end portion 31 of the Bourdon tube 3. Therefore, the brazing material 8 smoothly melted between the mounting hole 1B and the base end portion 31 can be easily allowed to flow from the space toward the back of the mounting hole 1B, so that the bonding area of the brazing material 8 can be further increased. Can be secured.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above-described embodiment, the notch 9 has a configuration in which the base end portion 31 of the Bourdon tube 3 is obliquely cut. However, the notch 9 of the present invention is not limited to the configuration of the above-described embodiment. 7A and 7B and FIGS. 8A and 8B may be used.
FIG. 7A is a front view of a Bourdon tube according to a modification of the present invention, and FIG. 7B is a side view thereof. In these drawings, the notch 91 is formed by cutting the open end of the base end portion 31 of the Bourdon tube 3 into a front V-shape.
FIG. 8A is a front view of a Bourdon tube according to another modification of the present invention, and FIG. 8B is a side view thereof. In these drawings, the notch 92 is formed by cutting the open end of the base end portion 31 of the Bourdon tube 3 into a front rectangular shape.
In these modified examples, the same effects as those of the above-described embodiment can be obtained.

Furthermore, in the present invention, the air discharge path is not limited to the notches 9, 91, 92 provided in the Bourdon tube 3, and may be formed in the attachment hole 1B of the joint 1, for example. For example, the base end portion 31 of the Bourdon tube 3 is cut so as to be orthogonal to the shaft core as in the prior art, and the bottom surface 1B1 is formed obliquely (at an angle other than a right angle) with respect to the shaft core in the mounting hole 1B. But you can.
In the present invention, the Bourdon tube 3 is not limited to the helical type shape shown in the above embodiment, but may be a C type type or a spiral type shape.
Furthermore, this invention is not limited to what is applied to a pressure gauge, It can apply also to the thermometer using a Bourdon tube.

  The present invention can be used for pressure gauges and other measuring instruments.

The front view which shows the internal structure of the pressure gauge concerning one Embodiment of this invention. The side view which shows the internal structure of a Bourdon tube. (A) is a front view of a joint, and (B) is a side view of the joint. (A) is a bottom view of the Bourdon tube, (B) is a cross-sectional view taken along line BB in (A), (C) is a front view of the Bourdon tube, and (D) is a side view of the Bourdon tube. Sectional drawing which shows the principal part of the said embodiment. BRIEF DESCRIPTION OF THE DRAWINGS (A) to (E) is a schematic diagram illustrating a method for attaching a Bourdon tube to a joint according to an embodiment of the present invention. (A) is a front view of a Bourdon tube according to a modification of the present invention, and (B) is a side view of the Bourdon tube. (A) is a front view of a Bourdon tube according to another modification of the present invention, and (B) is a side view of the Bourdon tube.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Joint, 1A ... Pressure introducing hole, 1B ... Mounting hole, 1B1 ... Bottom surface, 2 ... Case, 3 ... Bourdon tube, 31 ... Base end part, 32 ... Spiral part, 33 ... Tip part, 7 ... Pointer, 8 ... Brazing material, 9, 91, 92 ... Notch (air discharge path)

Claims (5)

This is a Bourdon tube mounting structure in which the base end of a Bourdon tube is inserted into a mounting hole formed in a joint, and brazing material is introduced between the base end of the inserted Bourdon tube and the mounting hole to braze. And
Forming an air discharge path in the base end portion of the Bourdon tube to discharge air accumulated in the mounting hole when a brazing material enters between the mounting hole and the base end portion of the Bourdon tube;
A mounting structure for a Bourdon tube, wherein the mounting hole is formed with a bottom surface against which a base end portion of the Bourdon tube abuts, and the air discharge path is a notch formed in a base end portion of the Bourdon tube. In the Bourdon tube mounting structure according to claim 1 ,
The Bourdon tube is characterized in that the notch is formed to cross obliquely at an angle of more than 0 ° and less than 90 ° with respect to a plane orthogonal to the axis of the base end portion of the Bourdon tube Mounting structure. In the mounting structure of the Bourdon tube according to claim 1 or 2 ,
The bourdon tube mounting structure is characterized in that the bourdon tube is a helical type bourdon tube. A pressure gauge comprising the Bourdon tube mounting structure according to any one of claims 1 to 3 , wherein a tip of the Bourdon tube is connected to a pointer. Bottom rear end of the bourdon tube abuts plug the Bourdon tube to the mounting hole is formed, flowing a brazing material between the rear end of the bourdon tube is inserted the heating the adoptive hand with the mounting hole A method for attaching a Bourdon tube to be brazed,
A brazing material melted between the mounting hole and the base end portion of the Bourdon tube is formed by previously forming an air discharge path which is a notch in the base end portion of the Bourdon tube and heating the joint. A method of attaching a Bourdon tube, wherein the air accumulated in the attachment hole is discharged through the air discharge passage when entering.

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