JPH1137874A - Pressure detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent a seal diaphragm from plastic deformation by forming the pressure receiving side surface of an oil spacer in a wave shape which is approximately the same as that of the seal diaphragm. SOLUTION: A base body 4, in which a pressure sensor 5 is placed on its upper surface is inserted to a housing part 3 for fixation. The pressure sensor 5 is provided with a sensor chip 5A where a gauge working as a piezo resistance area is joined to the upper surface of a seating 14 anodically. A pressure receiving side surface 6a opposite to a seal diaphragm 7 which is on the upper surface of an oil spacer 6 housing the pressure sensor 5, is formed as to have a concentric wave shape which is approximately the same as that of the seal diaphragm 7. Further, the center of a pressure receiving side surface 6a is coincided with that of the seal diaphragm 7 by pressing force of a spring pin 28 fitted to the upper surface of the base body 4. Thanks to such a structure, even if the seal diaphragm 7 is deformed by excessive pressure, is reaches a pressure receiving side surface 6a entirely and is fitted tightly thereto, so that it is hard to be deformed plastically or broken.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pressure detecting device for detecting a pressure or a differential pressure.

[0002]

[Prior art]

Conventionally, various pressure detecting devices using a semiconductor pressure sensor have been proposed (for example, Japanese Utility Model Laid-Open No.
No. 2-148826, Japanese Patent Publication No. 8-12931, etc.). In this type of pressure detection device, a gauge acting as a piezoresistive region is formed on the surface of a semiconductor substrate by impurity diffusion or ion implantation techniques, and a thickness of 20 μm to 50 μm is formed by removing a part of the back surface by etching. A pressure sensor having a deformable portion, that is, a diaphragm is used. Therefore, when a measurement pressure is applied to the front or back surface of the diaphragm during measurement, the specific resistance of the gauge changes with the displacement of the diaphragm, and the output voltage accompanying the resistance change at this time is detected, and the pressure or differential pressure is measured. it can.

FIG. 2 shows a conventional example of this type of pressure detecting device. This pressure detecting device 1 is provided with a storage section 3 in the center of the upper surface of a package 2 formed of a metal such as SUS316, and stores a pressure sensor 5 and an oil spacer 6 in the storage section 3 via a base 4. The storage section 3 is sealed in a liquid-tight manner by the diaphragm 7. The sealing diaphragm 7 is usually made of a thin metal plate such as phosphor bronze, beryllium copper, stainless steel, or the like. By forming corrugated folds in the radial direction at the time of processing, the compliance of the diaphragm is increased. Is softened, and the linear region satisfying the load-displacement equation is widened.

The oil spacer 6 is used to reduce the volume of the sealing liquid 11 and to prevent a volume change due to a temperature change as much as possible. The oil spacer 6 is usually made of ceramics such as alumina, and is fixed on the base 4 by an adhesive. I have. Further, inside the oil spacer 6, a sensor storage chamber 1 for storing the pressure sensor 5 and one end of the lead pin 9 is provided.
0 is formed, and the sealed liquid 11 for transmitting the measured pressure P1 applied to the seal diaphragm 7 to the pressure sensor 5 is sealed in the sensor storage chamber 10. As the filling liquid 11, silicone oil or the like is used. The pressure measuring chamber 1 formed between the seal diaphragm 7 and the oil spacer 6 is provided on the upper surface of the oil spacer 6.
2 and a pressure inlet 13 for communicating with the sensor storage chamber 10
Are formed.

In such a configuration, when the fluid to be measured is guided to the seal diaphragm 7, the seal diaphragm 7 is displaced in accordance with the pressure P1.
The pressure P1 can be detected by changing the pressure of the filling liquid 11 in 2 and displacing the strain-generating portion of the pressure sensor 5 and converting the strain amount into an electric signal and extracting the electric signal. In addition,
When excessive pressure is applied, the seal diaphragm 7
The oil diaphragm 6 to the pressure receiving side surface 6a, thereby preventing damage to the seal diaphragm 7, damage to the pressure sensor 5, and the like.

When such a pressure detecting device 1 is used for detecting a differential pressure, the pressure to be measured (P2) may be derived also on the lower surface side of the pressure sensor 5 to detect the differential pressure (P1-P2). In this case, a pressure inlet communicating with the storage section 3 is formed on the lower surface side of the package 2, and the measured pressure (P 2) guided to the pressure inlet passes through the inside of the base 4 and the pedestal 14 and the pressure sensor 5. May be guided to the back side of the camera. Reference numeral 16 denotes a sealing material for sealing the insertion hole 15 of the base 4,
Reference numeral 17 denotes a projection welding portion, 18 denotes a sealing ball for sealing the sealing liquid filling hole 19 of the package 2, 20 denotes a screw,
Reference numeral 21 denotes a welding ring of the seal diaphragm 7, and reference numeral 22 denotes a gold wire that electrically connects the pressure sensor 5 and the lead pin 9.

[0008]

As described above, in this type of pressure detecting device 1, when excessive pressure is applied, the seal diaphragm 7 is moved to the pressure receiving side surface 6 of the oil spacer 6.
a, the seal diaphragm 7 is damaged,
The damage of the pressure sensor 5 is prevented. However, conventionally, since the pressure receiving side surface 6a of the oil spacer 6 is simply formed as a smooth surface, when the sealing liquid 7 in the sensor chamber 10 leaks due to excessive pressure or some kind of accident, the sealing diaphragm 7 receives the pressure receiving side. There is a problem in that the rubber is landed on the side surface 6a and is plastically deformed or damaged. In particular, when the seal diaphragm 7 has landed and plastically deformed, a displacement corresponding to the pressure cannot be obtained, so that accurate measurement cannot be performed, and it is necessary to replace the seal diaphragm 7 with a new one. In addition, when it is damaged, the measurement becomes impossible and it is necessary not only to replace it with a new one, but also the sealed liquid 11 in the pressure measuring chamber 12 leaks outside.

In order to solve such a problem, there has been proposed a pressure sensor in which the surface on which the seal diaphragm bottoms is formed in the same shape as that of the seal diaphragm (Japanese Patent Application Laid-Open No. Hei 8 (1994)).
-12931). However, this pressure sensor uses a silicon substrate, and the surface facing the seal diaphragm is formed as a pressure receiving side surface having the same shape as the seal diaphragm by etching, so not only is the silicon substrate itself expensive, but also when forming the pressure receiving side, Since many steps such as a masking step, an etching step, a mask removing step, and a cleaning step are required, the production is extremely troublesome, and there is a problem that the price of the apparatus is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to make it inexpensive and easy to manufacture, and to apply an excessive pressure or leak a sealed liquid due to some accident. It is an object of the present invention to provide a pressure detecting device capable of reliably preventing plastic deformation or breakage of a seal diaphragm even in such a case.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an oil spacer containing a pressure sensor in a sensor storage chamber and filled with a sealed liquid, a package containing the oil spacer, A seal diaphragm for sealing the opening of the package; a pressure measuring chamber communicating with the sensor storage chamber between the seal diaphragm and the oil spacer; and a pressure receiving chamber of the oil spacer opposed to the seal diaphragm. It is characterized in that the side surface is formed in a waveform substantially the same as the seal diaphragm.

In the present invention, the oil spacer is made of ceramics or the like, has a function of sealing the sealed liquid, and has a surface facing the seal diaphragm which forms a substantially identical wave-shaped pressure receiving side surface. Therefore, even if excessive pressure is applied or the sealed liquid leaks due to some accident and the seal diaphragm bottoms on the pressure receiving side surface, there is no plastic deformation or breakage. The oil spacer reduces the amount of the sealed liquid, is inexpensive, and easily forms the pressure receiving side surface.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a sectional view showing an embodiment of the pressure detecting device according to the present invention. In the drawing, the same components as those shown in the section of the prior art are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The base 4 on which the pressure sensor 5 is installed at the center of the upper surface is fitted and fixed in the storage section 3 provided in the package 2.
The base 4 is formed of a material having excellent corrosion resistance and weldability and having a thermal expansion coefficient substantially equal to that of the pedestal 14, for example, Kovar.
The lead pin 9 is provided through. The insertion hole 15 of the base 4 through which the lead pin 9 penetrates is hermetically sealed by a sealing material 16 in order to electrically insulate the base 4 from the lead pin 9 and prevent leakage of the liquid filling 11. Such a base 4 is usually welded to the package 2 by projection welding in order to prevent the leakage of the sealed liquid 11. Therefore, an annular projection 17 (projection welded portion) is provided near the outer periphery of the lower surface of the base 4.
Are projected integrally, and this projection weld portion 17 is welded to the inner bottom surface 3a of the storage portion 3. Projection welding is a process in which a projection (also called projection or embossing) is provided on a workpiece, or a projection or an edge that is present at the time of processing the workpiece is used, and current is applied while applying pressure to the portion to be welded. This is a method of welding in an extremely short time, which is different from normal welding in that welding is performed while applying pressure.

The pressure sensor 5 has a sensor chip 5A in which a gauge acting as a piezoresistive region is formed on the surface of a strained portion of a semiconductor substrate by an impurity diffusion or ion implantation technique.
Anodically bonded to the upper surface of As the pedestal 14, the thermal strain when the sensor chip 5 </ b> A is joined is
When transmitted to A, the temperature characteristic of the pressure detecting device 1 is reduced and causes a zero point shift. Therefore, a material having a thermal expansion coefficient close to the thermal expansion coefficient of the sensor chip 5A, for example, Pyrex glass, ceramics, or the like is used.

The oil spacer 6 that houses the pressure sensor 5 and fills the filling liquid 11 is made of ceramics or the like. The upper surface of the oil spacer 6, that is, the pressure receiving side surface 6a facing the seal diaphragm 7 is formed as a concentric corrugated surface having substantially the same shape as the seal diaphragm 7. Such an oil spacer 6 is in close contact with the upper surface of the base 4 and is urged in the center direction by three spring pins 28 arranged at equal intervals in the circumferential direction so as to coincide with the center of the package 2. I have. Thus, the center of the pressure receiving side surface 6 a coincides with the center of the seal diaphragm 7. The spring pin 28 is press-fitted into a gap between the recess 27 provided on the outer peripheral surface of the oil spacer 6 and the inner wall surface of the housing 3.
Although the sensor chamber 10 and the pressure measuring chamber 12 communicate with each other through the pressure introduction port 13, the pressure introduction port 13 is not always necessary because they are communicated with each other through the gap between the package 2 and the oil spacer 6. Other configurations are the same as the conventional structure shown in FIG.

The pressure detecting device 25 having such a structure
In this case, when the filled liquid 11 in the pressure measuring chamber 10 leaks due to excessive pressure or some accident, plastic deformation or breakage of the seal diaphragm 7 can be reliably prevented. That is, since the pressure receiving side surface 6a of the oil spacer 6 is formed in substantially the same waveform as the seal diaphragm 7, when the seal diaphragm 7 is displaced due to excessive pressure or leakage of the sealing liquid 11, the entire surface of the pressure receiving side surface 6a is attached. There is no plastic deformation or breakage because it is close to the bottom. Further, since the oil spacer 6 is formed of ceramics or the like and is formed by molding, it is easier and less expensive to form the pressure receiving side than in the case where the pressure receiving side is formed on the conventional silicon substrate described above. Further, when the pressure measuring chamber 11 is formed by the oil spacer 6, the storage space for the sensor can be made smaller than when the pressure sensor 5 is directly stored in the storage chamber 3 of the package 2. There is an additional effect that the amount can be reduced.

It should be noted that the present invention is not limited to the above-described embodiment, and various changes and modifications are possible.
For example, the present invention can be applied to a detector in which a high pressure and a low pressure are guided to both surfaces of the sensor chip 5A and the differential pressure is measured.

[0018]

As described above, in the pressure detecting device according to the present invention, since the pressure receiving side surface of the oil spacer is formed in a waveform having substantially the same shape as that of the seal diaphragm, an excessive pressure is applied or the filled liquid is filled. When a leak occurs in an accident, plastic deformation or breakage of the seal diaphragm can be reliably prevented. In the present invention, since the oil spacer can be manufactured by molding,
It is easier and cheaper to manufacture than one using a conventional silicon substrate. Further, since the pressure measuring chamber is provided in the oil spacer, the amount of the sealed liquid can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a conventional example of a pressure detecting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pressure detection device, 2 ... Package, 3 ... Storage part, 4 ...
Base, 4A: Thin portion of base, 5: Pressure sensor, 5A: Sensor chip, 6: Oil spacer, 6a: Pressure receiving side, 7
... Seal diaphragm, 9 ... Lead pin, 10 ... Sensor storage chamber, 11 ... Filled liquid, 12 ... Pressure measuring chamber, 13 ... Pressure introduction port, 14 ... Base, 15 ... Insertion hole, 16 ... Seal material, 17
... projection welds.

Claims (1)

[Claims] An oil spacer containing a pressure sensor in a sensor storage chamber and filled with a sealing liquid, a package for storing the oil spacer, and a seal diaphragm for sealing an opening of the package are provided. A pressure measuring chamber communicating with the sensor storage chamber is provided between the seal diaphragm and the oil spacer, and a pressure receiving side of the oil spacer facing the seal diaphragm is formed to have substantially the same waveform as the seal diaphragm. Characteristic pressure detecting device.