JP3141371B2 - Differential pressure measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure measuring device capable of removing dust and preventing abnormal operation of a sensor portion, having high reliability and reducing manufacturing costs.

[0002]

2. Description of the Related Art FIG. 7 is an explanatory view of the structure of a conventional example generally used in the prior art.
This is shown in FIG. In the figure, housing 1
Flanges 2 on both sides, flanges 3 are fixed by the mating assembled welding, inlet 5 of the high-pressure fluid in the pressure P _H to be measured cents on both flanges 2 and 3, the pressure P _L
Of the low-pressure fluid is provided.

[0003] A pressure measuring chamber 6 is formed in the housing 1, and a center diaphragm 7 and a silicon diaphragm 8 are provided in the pressure measuring chamber 6. The silicon diaphragm 8 has a recess 82 formed in a single crystal silicon substrate 81.
Is formed.

The center diaphragm 7 and the silicon diaphragm 8 are separately fixed to the wall of the pressure measuring chamber 6, respectively.
The pressure measuring chamber 6 is divided into two parts by the two. Back plates 6A and 6B are formed on the wall of the pressure measurement chamber 6 facing the center diaphragm 7. The center diaphragm 7 has its peripheral edge welded to the housing 1.

An impurity such as boron is selectively diffused on one surface of the silicon substrate 81 to form four strain gauges 91. The four strain gauges 91 pull when the silicon diaphragm 8 bends by receiving the differential pressure ΔP,
Two are subject to compression and these are
Connected to the Toston bridge circuit, the resistance change is differential pressure Δ
It is detected as a change in P.

A lead 92 has one end attached to the strain gauge 91. Reference numeral 93 denotes a hermetic terminal to which the other end of the lead 92 is connected. The support 9 is provided with
A silicon diaphragm 8 is adhered and fixed to an end surface of the support 9 on the pressure measurement chamber 6 side by a method such as low-melting glass connection.

Pressure introducing chambers 10 and 11 are formed between the housing 1 and the flanges 2 and 3. First and second seal diaphragms 13 and 12 are provided in the pressure introduction chambers 10 and 11, and walls 10 A and 11 A of the housing 1 facing the seal diaphragms 12 and 13.
A back plate having a shape similar to that of the seal diaphragms 12 and 13 is formed.

The space formed by the seal diaphragms 12 and 13 and the back plates 10A and 11A and the pressure measurement chamber 6 are in communication with each other through communication holes 14 and 15. Filled liquids 101 and 102 such as silicon oil are filled between the seal diaphragms 12 and 13, and the filled liquids reach the upper and lower surfaces of the silicon diaphragm 8 through the communication holes 16 and 17. Is divided into two parts by the center diaphragm 7 and the silicon diaphragm 8, but care is taken so that the amounts are substantially equal.

In the above configuration, when a pressure acts from the high pressure side, the pressure acting on the seal diaphragm 13 is transmitted to the silicon diaphragm 8 by the sealing liquid 102. On the other hand, when pressure acts from the low pressure side, the pressure acting on the seal diaphragm 12 is transmitted to the silicon diaphragm 8 by the sealing liquid 101.

As a result, the silicon diaphragm 8 is distorted in accordance with the pressure difference between the high pressure side and the low pressure side, and the amount of this distortion is electrically taken out by the strain gauge 91 to measure the differential pressure. .

[0011]

However, in such an apparatus, since the silicon diaphragm 8 and the strain gauge 91 are manufactured by a semiconductor process, they can be made extremely small. Therefore, the filling liquid 101,
The gap in the measurement chamber or the like in which the space 102 is sealed is also a gap with an extremely narrow interval.

On the other hand, the housing 1 for housing such a sensor is made of metal. Since the housing 1 is subjected to complicated processing such as screws and holes, there are many extremely fine chips and burrs. In addition, dust such as spatter due to welding also exists.

In such a situation, a sensor is incorporated, and sealed liquids 101 and 102 such as silicon oil are sealed therein. At this time, even if the housing 1 is sufficiently washed and fine dust in the sealing liquids 101 and 102 is strictly removed by a filter, it is not economical and costly to completely remove the dust. In particular, it is difficult to remove burrs generated inside the housing 1. Further, the burrs are difficult to peel off from the housing 1, and it is not known when the burrs are peeled off due to the movement of the filling liquids 101 and 102.

The injection of the filling liquids 101 and 102 moves such dust in the housing 1 and moves the dust to the sensor portion, thereby causing an abnormal operation of the sensor portion. The present invention solves this problem. An object of the present invention is to provide a differential pressure measuring device which can remove dust, prevent abnormal operation of a sensor portion, have high reliability, and can reduce manufacturing cost.

[0015]

In order to achieve this object, the present invention relates to a differential pressure measuring apparatus having a housing made of metal filled with a sealing liquid and a measuring diaphragm made of a semiconductor. A silicon substrate, first and second glass substrates sandwiching the silicon substrate, first and second measurement chambers respectively provided opposite to both surfaces of the silicon substrate and forming a measurement diaphragm on the silicon substrate,
A first filter portion formed in the silicon substrate or the first glass substrate and configured by a plurality of mesh-shaped etching grooves, forming a first communication hole that communicates the first measurement chamber with the outside; A second filter portion formed in the silicon substrate or the second glass substrate and configured with a plurality of mesh-shaped etching grooves, forming a second communication hole communicating the second measurement chamber with the outside; A differential pressure measuring device is characterized in that:

[0016]

In the above construction, when pressure acts from the high pressure side, the pressure acting on the liquid diaphragm is transmitted to the silicon diaphragm by the sealed liquid. On the other hand, when pressure acts from the low pressure side, the pressure acting on the liquid diaphragm is transmitted to the silicon diaphragm by the sealing liquid.

As a result, the silicon diaphragm is distorted according to the pressure difference between the high-pressure side and the low-pressure side, and the amount of this distortion is electrically taken out by the strain gauge, and the differential pressure is measured.

The fine dust remaining in the housing part is moved by the flow of the sealing liquid when the sealing liquid such as silicone oil flows into the housing. Try to flow in.
However, in the first filter unit or the second filter unit, the inflow of these dusts into the sensor unit is prevented. Hereinafter, a detailed description will be given based on embodiments.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
2 is a sectional view taken along line AA of FIG. 1, FIG. 3 is a sectional view taken along line BB of FIG. 1, and FIGS. In the drawing, the same reference numerals as those in FIG. 7 indicate the same functions. Hereinafter, only differences from FIG. 7 will be described.

Reference numeral 21 denotes a plate-like silicon substrate. 2
Reference numerals 2 and 23 denote first and second glass substrates which hold the silicon substrate 21 therebetween. In this case, the silicon substrate 21 and the first and second glass substrates 22 and 23 are anodically bonded.

Reference numerals 24 and 25 denote first and second measurement chambers provided opposite to both surfaces of the silicon substrate 21 and forming a measurement diaphragm 26 on the silicon substrate 21.
In this case, the first and second measurement chambers 24 and 25 are formed of gaps with extremely narrow intervals, and when an excessive pressure is applied,
The measurement diaphragm 26 is connected to the first or second measurement chamber 2.
The sensor portion itself is configured so as to have an overpressure protection mechanism that directly contacts the walls 4 and 25 and protects the measurement diaphragm 26.

In this case, as shown in FIG. 4, the first and second glass substrates 2 are provided on the surface of the measurement diaphragm 26.
Silicon nitride film 2 so as not to be anodically bonded to
61 are provided with a thickness of about 1000 angstroms.

Reference numeral 27 denotes a first measuring chamber 24 as shown in FIG.
A first communication hole which communicates with the outside and is formed in the silicon substrate 21 and is a first filter portion formed by a plurality of mesh-like etching grooves. As shown in FIG. 4, it is desirable that the plurality of mesh-like etching grooves be provided radially from the center of the measurement diaphragm 26. In FIG. 2, the mesh-like etching grooves of the plurality of meshes are shown in a grid pattern, but this is because the distribution of the mesh-like etching grooves is simply shown for easy understanding.

Reference numeral 28 denotes a second measuring chamber 25 as shown in FIG.
A second communication hole that communicates with the outside, is formed in the silicon substrate 21, and is a second filter portion formed by a plurality of mesh-like etching grooves.

In the above configuration, when pressure acts from the high pressure side, the pressure acting on the liquid diaphragm 12 is transmitted to the silicon diaphragm 8 by the filling liquid 101. On the other hand, when pressure acts from the low pressure side, the pressure acting on the liquid diaphragm 13 is transmitted to the silicon diaphragm 8 by the filling liquid 102.

As a result, the silicon diaphragm 8 is distorted in accordance with the pressure difference between the high pressure side and the low pressure side, and the amount of this distortion is electrically taken out by the strain gauge 80, and the differential pressure is measured. .

The fine dust remaining in the housing part 1 is filled with the liquid 101 or 102 such as silicone oil when the liquid flows into the housing 1. Move and fill liquid 10
An attempt is made to flow into the sensor unit together with 1,102.

However, in the first filter section 27 or the second filter section 28, the inflow of these dusts into the sensor section is prevented.

Also, the filter section 2 is provided on the sensor section itself.
7 and 28, the housing 1 made of metal is provided.
Cleaning at normal cleaning level, foreign matter management
It is concentrated on the manufacturing process of the sensor unit. The manufacturing process of the sensor unit is a semiconductor manufacturing process, and the cleanness of the clean room is much better than, for example, a class 1000 level as compared with the whole assembly process of the differential pressure measuring device, so that the cleaning cost can be easily reduced.

In the case where the sensor portion itself has the overpressure protection mechanism as in the above-described embodiment, the silicon substrate 2
The gap between the first and second glass substrates 22 and 23, that is,
The gap between the first and second measurement chambers 24 and 25 is 2 to 5 μm.
It is not easy to remove the dust of 2 to 5 μm or more and assemble the entire differential pressure measuring device.

However, in the case of the present invention, since the filter portions 27 and 28 are provided in the sensor portion itself, attention must be paid to the assembling of the silicon substrate 21 and the first and second glass substrates 22 and 22. This is only at the time of joining with the sealing member 23, and there is no need to fill the filling liquids 101 and 102 and to increase the dust management level in the welding process and the like.

FIG. 6 is an explanatory diagram of a main part configuration of another embodiment of the present invention. In this embodiment, the first and second measurement chambers 3
1 and 32 are provided on the first and second glass substrates 21 and 22,
The measurement diaphragm 33 is configured.

In the above embodiment, the first and second filter portions 27 and 28 have been described as being provided on the silicon substrate 21. However, the present invention is not limited to this. Two glass substrates 22 and 23 may be provided respectively. In short, the silicon substrate 21 and the first and second
The filter may be a filter section in which a mesh-like groove is formed at a joint portion between the glass substrates 22 and 23 by etching in a semiconductor process and communicates the first and second measurement chambers 31 and 32 with the outside.

[0034]

As described above, the present invention relates to a differential pressure measuring apparatus having a housing made of metal filled with a filling liquid and a measuring diaphragm made of a semiconductor.
A plate-shaped silicon substrate, first and second glass substrates sandwiching the silicon substrate, and first and second measurement chambers respectively provided on both sides of the silicon substrate so as to constitute a measurement diaphragm on the silicon substrate And a first filter portion that forms a first communication hole that communicates the first measurement chamber with the outside and is formed on the silicon substrate or the first glass substrate and that includes a plurality of mesh-shaped etching grooves. A second communication hole for communicating the second measurement chamber with the outside, and a second filter portion formed on the silicon substrate or the second glass substrate and formed by a plurality of mesh-like etching grooves. A differential pressure measuring device characterized by comprising:

As a result, the silicon diaphragm is distorted according to the pressure difference between the high-pressure side and the low-pressure side, and the amount of this distortion is electrically taken out by the strain gauge, and the differential pressure is measured.

The small dust remaining in the housing part is moved by the flow of the sealed liquid such as silicone oil when the sealed liquid such as silicone oil flows into the housing. Try to flow in.
However, in the first filter unit or the second filter unit, the inflow of these dusts into the sensor unit is prevented.

Further, since the filter portion is provided in the sensor portion itself, the cleaning of the housing made of metal can be performed at a normal cleaning level, and the control of foreign substances is concentrated in the manufacturing process of the sensor portion. The manufacturing process of the sensor unit is a semiconductor manufacturing process, and the cleanness of the clean room is much better than, for example, a class 1000 level as compared with the whole assembly process of the differential pressure measuring device, so that the cleaning cost can be easily reduced.

Therefore, according to the present invention, dust is removed,
It is possible to realize a differential pressure measuring device that can prevent abnormal operation of the sensor portion, has high reliability, and can reduce the manufacturing cost.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along the line BB of FIG. 1;

FIG. 4 is a detailed explanatory view of a main part of FIG. 1;

FIG. 5 is a detailed explanatory view of a main part of FIG. 1;

FIG. 6 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 7 is an explanatory diagram of a configuration of a conventional example generally used in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... High pressure side flange 3 ... Low pressure side flange 4 ... Inlet 5 ... Inlet 6 ... Pressure measurement chamber 6A ... Back plate 6B ... Back plate 7 ... Center diaphragm 9 ... Support body 10 ... Pressure introduction Chamber 10A: Back plate 11: Pressure introduction chamber 11A: Back plate 12: Separating diaphragm 13: Separating diaphragm 14: Communication hole 15: Communication hole 16: Communication hole 21: Silicon substrate 22: First glass substrate 23 ... second glass substrate 24 ... first side constant chamber 25 ... second side constant chamber 26 ... measurement diaphragm 27 ... first filter 28 ... second filter 31 ... first side constant chamber 32 ... second side constant chamber 33 ... Measuring diaphragm 91 ... strain gauge 92 ... lead 93 ... hermetic terminal 101 ... filling liquid 102 ... filling liquid

Claims (1)

(57) [Claims] 1. A differential pressure measuring apparatus comprising: a housing made of a metal filled with a filling liquid and a measuring diaphragm made of a semiconductor; a plate-shaped silicon substrate; and first and second glasses sandwiching the silicon substrate A first substrate and a second substrate provided on both sides of the silicon substrate to form a measurement diaphragm on the silicon substrate;
A measurement chamber; and a first filter formed in the silicon substrate or the first glass substrate by forming a first communication hole that communicates the first measurement chamber with the outside and formed by a plurality of mesh-shaped etching grooves. And a second filter unit that forms a second communication hole that communicates the second measurement chamber with the outside and is formed on the silicon substrate or the second glass substrate and that includes a plurality of mesh-like etching grooves. A differential pressure measuring device comprising: