JPH11132885A - Pressure detector - Google Patents

Abstract

(57) [Problem] To prevent a change in the characteristics of a detection element even if the sealing property of a diaphragm is reduced. SOLUTION: A housing 7 and a recess 1a provided inside the housing.
A conductor 1 provided on the stem 1,
A pressure detecting element 2 electrically connected to a conductor;
In a pressure detecting device 100 provided with a medium 11 filled with the above, and a diaphragm 12 which is sandwiched between the stem 1 and the housing 7 and encloses the medium 11, a gel or a soft resin is used for the medium 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure detecting device, and more particularly to sealing a medium for receiving pressure from a port of the pressure detecting device and transmitting the pressure to a pressure detecting element.

[0002]

2. Description of the Related Art Conventionally, there has been known a pressure detecting device called a pressure sensor for detecting the pressure of a liquid or the like.
This device has a structure as shown in FIG.

That is, in the pressure detecting device 100, two through holes are formed in the stem 1, and a conductor pin 3 is fixed in one of the holes in a state where the periphery thereof is insulated. Are fixed with an adhesive or the like. The tip of the pin fixed to the stem is electrically connected to the detecting element by a method such as wire bonding, and the recess in which the detecting element is arranged is formed by welding the diaphragm 4 on the contact surface with the stem 1. , To be completely isolated from the pressure medium to be detected.

Further, a medium 5 for transmitting pressure is inserted into another through-hole (liquid injection hole) 1 in a concave portion in which the detecting element is disposed.
From 1, the concave portion is filled, and at this time, the pressure is set to a low pressure to be in a state of vacuum degassing. After the injection of the medium is completed, the steel ball 6 is inserted, and the steel ball is pressed with the screw 16 to completely seal it. After that, the O-ring 10 is fitted around the outer periphery of the stem thus subassembled, put into the housing 7, and the stem is prevented from coming off from the housing with the stem inserted into the housing. It is assembled by fixing with an annular stopper 8.

When such a pressure detecting device is connected to an external object to be detected, a pressure (pressure of the object to be detected) introduced from a port 9 provided in a housing is passed through a diaphragm and a sealed liquid. To the detection element, and then to the detection element 2. Thereafter, the strain gauge provided on the detecting element 2 is deformed, and the deformed signal is converted into an electric signal and transmitted to a signal processing circuit outside the pressure detecting device via the pin 3.

As described above, an apparatus for injecting the medium 5 after fixing the diaphragm 4 to the stem 1 and sealing the medium after the injection is disclosed in, for example, US Pat. No. 4,563,903.
In addition, to simplify the assembly, the diaphragm is sandwiched between the stem and the housing, and the medium is sealed with a rubber material.
Is disclosed in JP-A-63-85325.

[0007]

However, when a rubber material is used for the diaphragm as in the latter publication, the medium can be sealed by a simple assembling process, so that the manufacturing cost can be reduced. Since a rubber material is used for the diaphragm, the characteristics of the detection element change due to deterioration of the sealing property due to transmission of the pressure medium and deterioration of the rubber material.

Accordingly, the present invention has been made in view of the above problems, and even if the pressure medium permeates through the diaphragm or the sealing property is deteriorated due to the deterioration of the material of the diaphragm, the characteristic change of the detecting element is prevented. It is a technical object to prevent the occurrence of pressure and improve the reliability of the pressure detecting device.

[0009]

The technical measures taken to solve the above-mentioned problems include a housing, a stem provided inside the housing and having a concave portion, and a stem communicating with the concave portion. A conductor provided in the stem, a pressure detecting element provided in the recess and electrically connected to the conductor, a medium filled in the recess, and a diaphragm sandwiched between the stem and the housing and enclosing the medium. In the pressure detection device provided, gel or soft resin was used for the medium.

According to the above configuration, even if water contained in the pressure medium penetrates the diaphragm by using the gel or the soft resin for the medium, the gel or the soft rubber is interposed between the diaphragm and the detecting element. As a result, moisture does not permeate to the detection element, the contact of the detection element is prevented, and the reliability of the pressure detection device is improved.

In this case, if ceramics are used for the stem, the ceramics have excellent adhesion between the gel or rubber and the organic substance, so that peeling does not occur at the interface between the medium and the stem, and strong adhesion is obtained. As a result, moisture hardly accumulates on the surface of the stem in which the medium is sealed, so that the reliability is further improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing a structure of a pressure detecting device 100 according to the present invention. FIG. 2A is an enlarged view of a main part of a pressure detecting element (hereinafter referred to as a detecting element) 2 shown in FIG. FIG. 3B shows a detection unit 2a provided on the side receiving the pressure of the detection element 2 (under the detection element 2 shown in FIG. 1).

Therefore, description will be made with reference to FIG. The pressure detecting device 100 has a stem 1 disposed in a housing 7. The stem 1 is made of ceramics and has a through hole in the vertical direction shown in FIG.
A pin 3 of a conductor made of iron or the like is inserted and fixed and supported by glass welding at a joint 3a. Further, the stem 1 has a space of a concave portion 1a having two steps on the pressure receiving side, and the detecting element 2 is fixed to the bottom 1e of the concave portion 1a by an epoxy or fluorosilicone adhesive.

Next, the detecting element 2 will be described in detail with reference to FIG. 2. The detecting element 2 has a detecting portion 2a on the side receiving pressure, and a vacuum chamber 2c is provided on a base 2b made of glass or the like.
Is internally bonded to the pedestal 2b by anodic bonding. A bridge-type diffusion resistance (strain gauge) 2aa is disposed on the silicon chip 2d as shown in FIG. 2B, and a vacuum chamber 2c is formed in the silicon chip 2d. The central portion is thin and easily displaced. Each strain gauge 2
aa is electrically connected to each of the electrode pads 2ab in a pattern, and the signal is transmitted to a signal processing device (not shown) provided outside the pressure detection device 100 via the pins 3 connected by wire bonding from the electrode pads 2ab. It is configured to be transmitted.

The recess 1 of the stem 1 in which the detecting element 2 is arranged
A is provided with a circumferential joining surface 1b to which a diaphragm 12 made of a rubber material is fixed, and fills the concave portion 1a with a medium 11 that transmits pressure to the concave portion 1a. The medium 11 is made of gel or soft rubber, and has a circular diaphragm 1 corresponding to the size of the joining surface so as to enclose the medium 11.
With the cover 2 covered from above the joint surface, the housing 7 is press-fitted and the medium 11 is sealed by the diaphragm 12.
In this manner, the medium 11 can be sealed in the stem by the diaphragm 12, so that the assembly is simplified.

After the diaphragm 12 is fixed to the stem 1 by press-fitting as described above, an annular stopper 8 conforming to the shape of the hole for arranging the stem is fitted into the housing 7 with a screw to detect pressure. The device 100 is assembled.

According to such a method, the sealing of the medium 4 and the fixing of the diaphragm 11 can be performed at the same time, so that it is not necessary to make a hole for injecting the liquid 4 into the stem 1 as in the prior art, and the structure of the stem 1 is simplified In addition, the step of enclosing the liquid 4 with steel balls after the liquid 4 is injected through the injection hole is not required.

Since ceramics is used as the material of the stem 1, the ceramics have excellent adhesiveness between gel or rubber and an organic substance, so that separation does not occur at the interface between the medium 11 and the stem 1. Since strong adhesion is obtained, moisture hardly accumulates on the surface of the stem in which the medium 11 is sealed, thereby further improving reliability.

[0020]

According to the present invention, a housing, a stem provided inside the housing and having a recess, a conductor provided on the stem in communication with the recess, and the conductor provided on the recess are provided. In a pressure detection device having an electrically connected pressure detection element, a medium filled in the concave portion, and a diaphragm sandwiched between the stem and the housing and enclosing the medium, gel or soft resin is used for the medium. By using,
Even if moisture in the pressure medium permeates the diaphragm, no water permeates to the detection element because gel or soft rubber is interposed between the pressure element and the detection element. To prevent touch,
The reliability of the pressure detection device is improved.

In this case, if ceramics is used for the stem, the ceramics have excellent adhesion between the gel or rubber and the organic substance, so that peeling does not occur at the interface between the medium and the stem, and strong adhesion is obtained. As a result, moisture hardly accumulates on the surface of the stem in which the medium is sealed, so that the characteristics of the detection element do not change, and the reliability is further improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a pressure detecting device according to an embodiment of the present invention.

2A is an enlarged view of a main part of the detection element shown in FIG. 1, and FIG. 2B is a view showing a detection unit of the detection element.

FIG. 3 is a diagram showing a structure of a conventional pressure detecting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stem 1a Recess 1b Joining surface 1c Step 2 Pressure detecting element (detecting element) 3 Pin (conductor) 7 Housing 11 Medium 12 Diaphragm (rubber material)

Claims (2)

[Claims] 1. A housing, a stem provided inside the housing and having a recess, a conductor provided in the stem in communication with the recess, and the conductor provided in the recess are electrically connected. A pressure sensing element, a medium filled in the recess, and a diaphragm sandwiched between the stem and the housing to seal the medium, wherein a gel or soft resin is used for the medium. Pressure detector. 2. The pressure detecting device according to claim 1, wherein ceramic is used for the stem.