JP2003194649A - Sealing method of oil filling pipe of liquid seal type pressure sensor, and liquid seal type pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing method of the oil filling pipe of a liquid seal type pressure sensor capable of reducing the leakage of oil to the utmost, having high reliability and stability over a long time and suitable for detecting high pressure, and to provide a liquid seal type pressure sensor composed by using the sealing method. <P>SOLUTION: In sealing the tip part of the oil filling pipe, the tip part is flatly collapsed into a cross-sectionally U-shaped or V-shaped form at first and thereafter sealed by welding or soldering. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sealing an oil filling pipe of a liquid ring pressure sensor and a liquid ring pressure sensor.

[0002]

2. Description of the Related Art Pressure sensors are widely used for converting physical quantities such as pressure and load into electrical signals such as voltage and current. This pressure sensor converts the change in strain of a thin disk called a diaphragm into a change in electrical resistance,
The change in resistance is taken out as an electric signal. With such a pressure sensor, pressure can be detected with a slight strain of the diaphragm, so that it is possible to maintain excellent stability for a long period of time, and it is possible to reduce the size and weight of the pressure sensor. There is also the advantage of not choosing.

In this type of pressure sensor, an incompressible fluid such as oil is enclosed in a liquid-sealed chamber partitioned by a diaphragm, and a pressure detecting element such as a piezoresistive pressure sensor is fixedly installed and acts on the diaphragm. The fluid pressure is transmitted to the pressure detection element via the fluid in the liquid sealing chamber,
As a result, the fluid pressure in the measured fluid area is detected. This type of pressure sensor is disclosed, for example, in Japanese Patent Publication No. 6-65.
It is described in detail in Japanese Patent Publication 974.

In the pressure sensor disclosed herein, a hollow pipe for oil filling is provided to seal the oil in the liquid sealing chamber of the liquid sealing type pressure sensor, and the oil is filled through this pipe. After the oil is filled, the hollow pipe filled with oil is welded or soldered to close the open end of the hollow pipe, thereby completely shutting off the fluid from the outside air. .

[0005]

By the way, in such a pressure sensor, the end portion of the oil filling pipe is simply flattened and then the sealed portion is sealed by soldering or welding. . However, in such a pressure sensor that seals the flatly crushed portion, the force for opening the crushed portion acts from the inside every time the internal pressure of the fluid is applied, and thus it is repeatedly used. Then, fatigue may occur, cracking may occur, and liquid leakage may occur. Therefore, it has a problem that it is not suitable for high pressure.

On the other hand, in such a conventional sealing method, oil flows out from an unsealed portion during the work process of welding or soldering, and the oil filling amount in the liquid sealing chamber decreases. There was a problem of being lost. Also, during the sealing process by welding or solder, the oil in the oil filling pipe is heated and vaporized by welding heat, etc., and the oil blown out from the oil filling pipe cannot reliably perform sealing by welding or the like. There were things.

In view of such conventional problems, the present invention can reduce oil leakage as much as possible, have high reliability and stability for a long period of time, and can also be applied to detect high pressure. Another object of the present invention is to provide a method for sealing an oil filling pipe of a liquid-sealed pressure sensor and a liquid-sealed pressure sensor.

[0008]

In order to achieve the above object, a method for sealing an oil filling pipe of a liquid-sealed pressure sensor according to the present invention fills a liquid-sealed chamber of the liquid-sealed pressure sensor with oil. In the method of sealing the oil filling pipe for
After the oil is filled, the tip portion of the oil filling pipe is crushed into a V-shaped cross section or a U-shaped cross section, and the crushed end face is welded or sealed with solder.

According to the method of the present invention as described above, since the tip end portion of the oil filling pipe is crushed into a V-shaped section or a U-shaped section after oil filling, a space between both walls of the crushed pipe is formed. Since the contact area becomes large, the gap becomes small, and the bent portion of the crushed portion of the pipe reduces deflection, so that the occurrence of liquid leakage can be minimized.

Here, in the method according to the present invention, in sealing the sealed portion of the crushed end face with welding or solder,
A first step of leaving a part of the sealed part and sealing the other part with welding or solder, and after a lapse of a predetermined time from the completion of the first step, the entire sealed part is removed. It is preferable that the second step of sealing is performed, and the sealed portion of the oil filling pipe is completely sealed by the second step.

According to such a method, the welding or the solder sealing in the first step is performed while leaving a part of the crushed end face to be sealed, so that even if oil remains in the crushed part, The oil escapes from the seal portion, so that the welding or soldering in the second step, which is performed after a lapse of a predetermined time, does not blow out the oil, and the sealing can be reliably performed.

Further, in the method according to the present invention, when the crushed end face is sealed by welding, it is possible to irradiate a laser beam with a small-diameter beam for sealing. According to such a method, it is possible to irradiate a laser beam with a small-diameter beam to surely perform the above-mentioned sealing. Furthermore, in the method according to the present invention, when the crushed end face is sealed by welding, laser light is emitted from a beam obtained by overfocusing an elliptic beam or a circular beam to seal the entire sealed portion at once. You can also do it.

According to such a method, laser light by a beam obtained by overfocusing a long elliptical beam or a circular beam is irradiated over the entire sealed portion of the crushed end face, and the entire sealed portion is sealed at once. It is stopped and can be completely sealed with one shot. Therefore, even if oil remains in the crushed portion, the oil does not blow out,
It can be surely sealed. Further, the liquid-sealing pressure sensor according to the present invention is a liquid-sealing pressure sensor in which pressure is detected by strain of a diaphragm in the liquid-sealing chamber in which oil is sealed, and the liquid-sealing chamber is filled with oil. The tip of the oil filling pipe is crushed into a V-shaped section or a U-shaped section after oil filling and is sealed by welding or soldering.

With the pressure sensor having such a structure, even if the internal pressure of the fluid is repeatedly applied, the deflection of the crushed portion can be reduced, so that the leakage of oil can be prevented as much as possible. Therefore, it can be applied to high pressure measurement and can maintain high reliability and stability for a long period of time.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for sealing an oil filling pipe and a liquid ring type pressure sensor according to the present invention will be described below with reference to the drawings. 1 and 2
FIG. 4 shows a liquid-sealed pressure sensor adopting the method for sealing an oil filling pipe according to an embodiment of the present invention.

This liquid-sealed pressure sensor is composed of a pressure detection element 10, a joint 20, and a connector housing 30 which are joined together. The pressure detection element 10 has an element body 11 made of metal, and a hermetic glass 13 is fixed to a central opening 12 of the body 11. On one end face of the pressure detection element 10,
An outer peripheral edge portion of the metal diaphragm 14 is fixed by welding, and a protective cover 15 having a communication hole 16 is attached below the diaphragm 14. In such a structure, in the central opening portion of the element body 11,
A liquid sealing chamber 17 in which oil is sealed is defined between the hermetic glass 13 and the metal diaphragm 14.

Liquid sealing chamber 17 for the hermetic glass 13
The sensor chip 4 with a one-chip structure is provided on the surface facing the
0 is fixed by an adhesive or the like. Further, a plurality of lead pins 18 for inputting and outputting a signal to and from the sensor chip 40 and an oil filling pipe 19 are penetratingly attached to the hermetic glass 13, and these are hermetically treated and fixed.

The lead pin 18 is electrically connected to the sensor chip 40 by a wire (not shown),
It constitutes an external output terminal and an external input terminal of the sensor chip 40. An FPC (flexible printed circuit) 31 is electrically connected to the lead pin 18, and
Connection terminal 3 of this FPC 31 and connector housing 30
And 2 are electrically connected.

On the other hand, the oil filling pipe 19 is used as a filling port for filling the liquid sealing chamber 17 with oil, and the tip portion 19a is liquid-tightly sealed after the oil filling as follows. . Below, this oil filling pipe 1
A method for sealing the tip portion 19a of the No. 9 will be described with reference to FIGS.

First, after the oil filling pipe 19 has been filled with oil, the tip portion 19a of the oil filling pipe 19 is crushed into a U-shaped cross section using a dedicated jig. In this case, first, as shown in FIG. 4, the pipe 19 is crushed in a stripe shape in a direction traversing the pipe 19, a temporary sealing portion 50 is provided therein, and the tip side thereof is U-shaped in cross section. It can also be crushed. By providing the temporary sealing portion 50 in this way, it is possible to prevent the oil from flowing out from the crushed end surface 52 of the oil filling pipe 19 during the sealing process by welding or solder which is performed later.

Further, if the temporary sealing portion 50 is provided near the tip end portion as described above, even if the oil remains on the tip end side of the temporary sealing portion 50, the amount of the oil is small, so that the oil is crushed later. Even if the end surface 52 is welded or soldered, a large amount of oil does not blow out during the work. Therefore, incomplete sealing due to welding or the like is prevented by the blown oil.

Further, when the crushed end face 52 is sealed by welding, the welding operation can be performed in two steps as shown in FIGS. 5 (A), (B) and (C). That is, first, in the first step of the first welding, as shown in FIG.
As shown in (A) and (B), of the sealed portion 53 of the crushed end surface 52 crushed into a substantially U shape, a portion 53a is left and the other portion is seam welded W1.

Then, after a lapse of a predetermined time from the completion of the seam welding W1 of the first step, as shown in FIG. 5C, the entire sealed portion 53 is seam welded W2. The seam welding W2 in the second step can completely seal the sealed portion 53 of the tip end portion 19a of the oil filling pipe 19. The seam welding W1 in the first step and the seam welding W2 in the second step can be performed by irradiating the laser beam from the small diameter beam Ba. Here, the beam diameter of the small diameter beam Ba is
It is about 0.3 mm, and irradiation may be performed from one end of the sealed portion 53. The size of the part 53a where the seam welding W1 in the first step is not performed may be the beam diameter of the small diameter beam Ba. Also, the seam welding W of the second step
In principle, only the part 53a may be welded in step 2, but in order to increase the reliability of the welding and sealing, it is also possible to repeat the welding from one end of the sealed part 53.

By thus sealing, both ends of the crushed end surface 52 are curved in an arc shape, so that a wide contact area between the inner side wall and the outer side wall forming the sealed portion 53 is secured. At the same time, since the contact surface is formed in a curved shape, in terms of material mechanics, the force that tends to widen between both walls even if pressure is applied to the inside of the sealed portion compared to when the sealed portion is a flat surface. Can withstand. Therefore, with such a sealing structure, oil leakage can be prevented as much as possible even if it is repeatedly used.

Further, as shown in FIG. 4 of this embodiment, when the temporary sealing portion 50 is provided in the direction traversing the pipe 19, sealing is performed by welding or sealing by soldering. In any case, oil is effectively prevented from flowing out from the oil filling pipe 19 during these sealing steps. Moreover, in the above embodiment, the first
The seam welding W1 during the process is a part 53 of the sealed portion 53.
Since other parts are welded except for a, even if oil remains in this tip, it is necessary to let the oil escape from the part 53a where seam welding is not performed before performing the welding in the second step. You can Therefore, in the seam welding W2 of the second step, which is performed after a certain amount of time has passed, oil does not blow out, so that welding sealing can be reliably performed.

As described above, in this embodiment, it is possible to provide a highly reliable and reliable pipe sealing in which no leakage occurs for a long period of time. Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in the above embodiment, the case where the seam welding is performed in two steps has been described. However, as shown in FIG. 6, if the oblong beam condensing lens 60 is used, the collapsed end face 52 is sealed. The elliptical beam B over the entire area of the portion 53
It is also possible to irradiate the laser beam of b to weld-seal the entire sealed portion 53 at once.

In this case, since the welding is performed all at once, even if the oil remains in the crushed portion on the tip side, the oil does not blow out, and the welding and sealing of the pipe tip can be reliably performed. Further, in the above embodiment, the tip end portion 19a of the oil filling pipe 19 is crushed into a substantially U-shaped cross section, but instead of this, as shown in FIG. 7, the tip end portion 19a is formed.
Can be crushed into a V-shaped cross section. Tip portion 19a
Even if it is crushed in this way, it is possible to obtain the same effects as those of the above-mentioned embodiment. Also in this case, it is possible to prevent oil from leaking over a long period of time and provide highly reliable and reliable pipe sealing.

In the above embodiment, the provision of the temporary sealing portion 50 has been described by taking the case of crushing in the U-shaped cross section as an example, but it is the case of crushing the tip portion 19a in the V-shaped cross section. However, such a temporary sealing portion 50 may be provided. However, the provision of the temporary sealing portion 50 is not limited at all, and the temporary sealing portion 50 can be collapsed into U or V by one operation.

[0029]

As described above, according to the oil filling pipe sealing method of the present invention, after the tip portion of the oil filling pipe is crushed into a V-shaped section or a U-shaped section, Since this part is sealed by welding or soldering, even if internal pressure acts on this part, the deflection of the material can be reduced compared to when the tip is flat, and oil leakage is minimized. Can be prevented. Therefore, even if a high pressure acts, it can withstand the high pressure and can contribute to the provision of a pressure sensor that detects a high pressure.

In welding the sealed portion, 2
If the welding is performed in separate steps, even if oil remains on the tip side, the oil can be released from the portion that was not welded in the first step. Therefore, when the welding in the second step is performed, the oil is not blown out and the welding sealing can be surely executed. Therefore, it is possible to perform reliable and reliable pipe sealing without oil leakage for a long period of time.

Further, by irradiating with a small-diameter beam, such seam welding can be easily performed in two steps. Further, by irradiating the elliptical beam or the circular beam with a laser beam of an overfocused beam, all can be sealed with one irradiation, and the work is easy. Further, according to the liquid ring type pressure sensor of the present invention, it is possible to widen the measurement range of the pressure sensor which has been unsuitable for the detection of the high pressure, and even in the case of detecting the low pressure. , Its reliability can be maintained for a long time, and liquid leakage does not occur.

[Brief description of drawings]

FIG. 1 is a sectional view of a liquid ring type pressure sensor to which a method for sealing an oil filling pipe according to an embodiment of the present invention is applied.

FIG. 2 is an enlarged cross-sectional view of a main part of the liquid ring type pressure sensor shown in FIG.

FIG. 3 is a perspective view showing a sealing structure of a tip portion of the oil filling pipe shown in FIG.

FIG. 4 is a sectional equivalent view of FIG. 3 according to another embodiment.

5 (A), (B), and (C) are front views of the crushed end face in the order in which the method for sealing the oil filling pipe shown in FIG. 1 is performed.

FIG. 6 is an explanatory view showing a sealing method according to another embodiment of the present invention.

FIG. 7 is a perspective view of a tip portion of an oil filling pipe of a liquid ring type pressure sensor according to another embodiment of the present invention.

[Explanation of symbols]

10 Pressure detection element 11 Element body 14 Metal diaphragm 15 Diaphragm protection cover 17 Liquid Sealing Room 19 Oil filling pipe 19a tip 20 joints 30 connector housing 32 connection terminals 50 Temporary sealing part 52 Crushed end face 53a part 53 Sealed part 60 oblong beam condensing lens Ba small diameter beam Bb elliptical beam

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuji Kimura             1311 Aobadai, Tokorozawa, Saitama Prefecture Made by Sagimiya Co., Ltd.             Sakusho Tokorozawa Office F term (reference) 2F055 AA40 BB20 CC02 DD20 EE11                       FF38 GG22 HH07

Claims (5)

[Claims] 1. A method for sealing an oil filling pipe for filling oil in a liquid sealing chamber of a liquid sealing type pressure sensor, wherein a tip portion of the oil filling pipe has a V-shaped cross section or a cross section after the oil filling. A method for sealing an oil filling pipe of a liquid-sealed pressure sensor, which comprises crushing into a U shape and sealing the crushed end face with welding or solder. 2. A first step of sealing a sealed portion of the crushed end face by welding or soldering, leaving a part of the sealed portion and sealing the other portion by welding or soldering, A second step of sealing the entire sealed portion after a lapse of a predetermined time after the completion of the first step, and the sealed portion of the oil filling pipe is removed by the second step. The method for sealing an oil filling pipe of a liquid-sealed pressure sensor according to claim 1, wherein the oil-sealed pipe is completely sealed. 3. The oil filling of the liquid-sealed pressure sensor according to claim 1 or 2, wherein when the crushed end face is sealed by welding, a laser beam with a small diameter beam is irradiated to seal the crushed end face. Pipe sealing method. 4. When the crushed end face is sealed by welding, laser light is emitted from a beam obtained by overfocusing an elliptical beam or a circular beam to seal the entire sealed portion at once. The method for sealing the oil filling pipe of the liquid-sealed pressure sensor according to claim 1. 5. A liquid-sealing type pressure sensor in which pressure is detected by strain of a diaphragm in a liquid-sealing chamber in which oil is sealed, the tip of an oil filling pipe for filling the liquid-sealing chamber with oil. The liquid-sealed pressure sensor is characterized by being crushed into a V-shaped section or a U-shaped section after being filled with oil, and sealed by welding or soldering.