Pressure detection unit, pressure sensor using the same, and method of manufacturing pressure detection unit

[Object] Provided are a pressure detection unit and a pressure sensor using the same capable of performing a trimming operation using a simple structure during an assembly operation, and reducing a decrease in detection accuracy of a semiconductor type pressure detection device.[Solving Means] A pressure detection unit includes a base formed in a lid shape and made of ceramic, a receiving member formed in a plate shape, a diaphragm interposed between the base and the receiving member, a semiconductor type pressure detection device installed on a side of a pressure receiving space formed between the base and the diaphragm in the base, and three terminal pins electrically connected to the semiconductor type pressure detection device, the terminal pins penetrating the base, wherein the three terminal pins include an earth terminal pin, a power input terminal pin, and a signal output terminal pin.

TECHNICAL FIELD

The present invention relates to a pressure sensor, and particularly relates to a liquid filling type pressure detection unit that accommodates a semiconductor type pressure detection device, and a pressure sensor using the same.

BACKGROUND ART

A liquid filling type pressure sensor in which a semiconductor type pressure detection device is accommodated inside a pressure receiving chamber partitioned by a diaphragm to be filled with oil has been used to detect a refrigerant pressure by being installed in a refrigerator-freezer or an air conditioner, or to detect a pressure of supplied oil by being installed in a fuel feeder of a vehicle.

The semiconductor type pressure detection device is disposed inside the pressure receiving chamber, and has a function of converting a pressure change inside a pressure receiving space into an electric signal and outputting the converted electric signal to the outside through a relay board or a lead wire.

Referring to such a pressure sensor, liquid such as water may enter the sensor from the outside to cause a defect in the semiconductor type pressure detection device depending on an environment in which the pressure sensor is installed or a usage condition of the device.

In this regard, there has been a known pressure sensor in which a cover is attached to a base accommodating a semiconductor type pressure detection device to fill the inside of the cover with an adhesive, thereby enhancing water tightness (see Patent Document 1).

CITATION LIST

Patent Document

Patent Document 1: JP 2012-68105 A

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

In the pressure sensor disclosed in Patent Document 1, normally, after the semiconductor type pressure detection device is attached to a central portion on an inner surface side of the base, the base, a diaphragm, and a receiving member are overlapped, subjected to girth welding, and integrated, thereby configuring a pressure detector.

In this instance, these members are formed using a metal material such as stainless steel, and thus the semiconductor type pressure detection device attached to the base detects distortion due to expansion or contraction in the base in a thermal history at the time of performing girth welding as a pressure change to be detected.

In addition, the semiconductor type pressure detection device detects a change in expansion or contraction of the base depending on a thermal environment in which the pressure sensor is used. Thus, for example, when a temperature difference in a usage environment is large, temperature correction (trimming) of the whole pressure sensor is required.

Further, such a trimming operation needs to be performed under a predetermined thermal environment after an assembly operation of the pressure detector or the whole pressure sensor, and a device for preparing the thermal environment, etc. is separately required.

Meanwhile, to perform the trimming operation after the assembly operation of the pressure detector or the pressure sensor, an adjustment terminal pin (lead pin) connected to the semiconductor type pressure detection device by penetrating the base needs to be provided in the pressure detector, and a process of providing the terminal pin, an additional material, etc. are required.

In addition, low-frequency electrical noise, so-called “common mode noise”, from a device in which the pressure sensor is installed may be delivered from a piping system to which a fluid introduction pipe of the pressure sensor is connected. When the number of terminal pins is large, such noise is delivered to the semiconductor type pressure detection device through the pressure detector, and there is a concern that detection accuracy may decrease.

In this regard, an object of the invention is to provide a pressure detection unit and a pressure sensor using the same capable of performing a trimming operation using a simple structure during an assembly operation, and reducing a decrease in detection accuracy of a semiconductor type pressure detection device.

Means for Solving Problem

To achieve the above-mentioned object, a pressure detection unit according to the invention includes a base formed in a lid shape and made of ceramic, a receiving member formed in a plate shape, a diaphragm interposed between the base and the receiving member, a semiconductor type pressure detection device installed on a side of a pressure receiving space formed between the base and the diaphragm in the base, and three terminal pins electrically connected to the semiconductor type pressure detection device, the terminal pins penetrating the base, wherein the three terminal pins include an earth terminal pin, a power input terminal pin, and a signal output terminal pin.

In a pressure detection unit according to an embodiment of the invention, a first brazing portion is formed between the base and the three terminal pins. In this instance, a metallized layer may be further formed between the base and the first brazing portion.

In addition, the pressure detection unit further includes a caulking member that caulks and integrates the base and the receiving member from outer circumferential sides.

In the pressure detection unit according to an embodiment of the invention, a ring member is further interposed between the base and the diaphragm.

In this instance, a second brazing portion may be formed between the base and the ring member, and a metallized layer may be further formed between the base and the second brazing portion.

The pressure detection unit according to the invention may be used as a part of a pressure sensor including a cover attached to the pressure detection unit, and a lead wire having one end electrically connected to a terminal pin of the pressure detection unit and the other end protruding to an outside of the cover.

A method of manufacturing a pressure detection unit according to an embodiment of the invention includes a terminal pin attachment process of attaching three terminal pins to a base formed in a lid shape and made of ceramic, the three terminal pins penetrating the base, an electric connection process of installing a semiconductor type pressure detection device at a central portion of the base, and electrically connecting the three respective terminal pins to the semiconductor type pressure detection device, and an integration process of integrating a diaphragm with the base and a receiving member formed in a plate shape while the diaphragm is interposed between the base and the receiving member.

Effect of the Invention

According to a pressure detection unit and a pressure sensor using the same of the invention, it is possible to perform a trimming operation using a simple structure during an assembly operation, and reduce a decrease in detection accuracy of a semiconductor type pressure detection device due to common mode noise, etc.

In addition, the pressure detection unit and the pressure sensor using the same of the invention is less affected by expansion or contraction of a base due to a change in thermal environment, and thus may suppress a decrease in detection accuracy due to the change in thermal environment.

MODE(S) FOR CARRYING OUT THE INVENTION

FIGS. 1A and 1Bdepict an outline of a pressure detection unit according to Embodiment 1 of the invention.FIG. 1Aillustrates a top view of the pressure detection unit, andFIG. 1Billustrates a cross section taken along A-A line ofFIG. 1Ain side view.

As illustrated inFIGS. 1A and 1B, a pressure detection unit100according to Embodiment 1 of the invention includes a base110made of ceramic, a receiving member120facing the base110, and a diaphragm130and a ring member140interposed between the base110and the receiving member120.

The base110is a circular lid-shaped member in top view, and includes a ceramic material having an insulating property in which an outer circumferential portion112and an inner portion114having a smaller thickness than that of the outer circumferential portion112are integrated with each other as illustrated inFIG. 1B. That is, the base110has a shape in which a central portion thereof is recessed such that a pressure receiving space S1described below is formed.

For example, a generally known material including an oxide such as alumina or zirconia, carbide such as silicon carbide, and a nitride such as silicon nitride may be used as the ceramic material included in the base110.

The sealed pressure receiving space S1is formed between the inner portion114of the base110and the diaphragm130, and filled with a liquid medium having an insulating property such as oil.

In addition, a semiconductor type pressure detection device150described below is installed at a central portion on the pressure receiving space S1side in the inner portion114of the base110.

As illustrated inFIG. 1A, a plurality of through-holes (see reference numeral116ofFIG. 1B) into which three terminal pins160,162, and164are inserted is formed at positions around the semiconductor type pressure detection device150in the base110.

Further, the terminal pins160,162, and164penetrate the base110by being inserted into the plurality of through-holes116, and one ends thereof are electrically connected to the semiconductor type pressure detection device150.

For example, the receiving member120is formed using a metal material such as a stainless steel plate, is a plate-shaped member subjected to press molding such that a central portion is recessed, and includes a cylindrical portion121having a bottom and a cylindrical shape and a flange portion122formed at an upper end of the cylindrical portion121(the receiving member120may be formed by cutting, etc. other than press molding).

An opening123for installing a fluid inlet pipe (described below) is formed on a bottom surface of the cylindrical portion121, and the diaphragm130is joined to an upper surface of the flange portion122.

According to this configuration, a pressurization space S2into which a fluid to be detected flows is formed between the receiving member120and the diaphragm130.

For example, the diaphragm130is formed as a disc-shaped thin plate member made of a metal material such as stainless steel. For example, the ring member140is formed as a ring-shaped member made of a metal material such as stainless steel.

Further, for example, the diaphragm130is subjected to girth welding by laser welding, etc. while being interposed between the receiving member120and the ring member140. In this way, the receiving member120, the diaphragm130, and the ring member140are integrated to form a pressure receiving structure.

The semiconductor type pressure detection device150is die-bonded to the central portion of the base110using adhesion, etc. The semiconductor type pressure detection device150includes a support substrate152made of glass and a pressure detection element (semiconductor chip)154joined to the support substrate152. As an example thereof, for example, the pressure detection element154includes eight bonding pads (electrodes). Three of the bonding pads correspond to a power input pad for an output signal, an earth pad, and a signal output pad. Further, remaining five bonding pads correspond to signal adjustment pads.

As illustrated inFIG. 1A, an earth terminal pin160, a power input terminal pin162, and a signal output terminal pin164are attached to the base110by penetrating the base110using brazing.

The earth terminal pin160, the power input terminal pin162, and the signal output terminal pin164are electrically connected to the earth pad, the power input pad, and the signal output pad of the semiconductor type pressure detection device150described above through a bonding wire166.

In addition, in the semiconductor type pressure detection device150electrically connected to the three terminal pins160,162, and164attached to the base110, a temperature correction operation (trimming operation) is performed by allowing a conducting probe to come into contact with the above-described respective eight pads.

As an example of a procedure of assembling the pressure detection unit100according to Embodiment 1 of the invention, first, the earth terminal pin160, the power input terminal pin162, and the signal output terminal pin164are inserted into the through-holes116formed in the base110, and the three terminal pins160,162, and164and the base110are subjected to brazing to form a first brazing portion (see reference symbol B1ofFIG. 1A), thereby joining and fixing the terminal pins160,162, and164to the base110(terminal pin attachment process). In other words, a brazing material such as silver solder is interposed between the through-holes116formed in the base110and the terminal pins160,162, and164, and heating is performed at a predetermined temperature in this state, thereby forming the first brazing portion B1between ceramic of the base110and metal of the terminal pins160,162, and164.

In this instance, wettability of the ceramic material and the brazing material may be enhanced by forming a metallized layer (for example, a Mo—Mn layer, etc.) in advance on a surface coming into contact with the brazing material of the base110before a brazing operation is performed.

Subsequently, the base110is joined to an upper surface of the ring member140(a surface on an opposite side from a surface on which the diaphragm130is welded) using a second brazing portion (see reference numeral B2ofFIG. 1A) (ring member joining process).

In the ring member joining process, for example, a brazing material such as silver solder is interposed between the base110and the ring member140, and heating is performed at a predetermined temperature in this state, thereby forming the second brazing portion B2between the ceramic material of the base110and the metal material of the ring member140.

In this instance, wettability of the ceramic material and the brazing material may be enhanced by forming a metallized layer (for example, a Mo—Mn layer, etc.) in advance on a surface coming into contact with the brazing material of the base110before the brazing operation is performed.

Subsequently, the semiconductor type pressure detection device150is die-bonded to the central portion of the base110.

Thereafter, the earth pad, the power input pad, and the signal output pad of the semiconductor type pressure detection device150are electrically connected to the one ends of the three terminal pins160,162, and164, respectively, through the bonding wire166(electric connection process).

Subsequently, the conducting probe is allowed to come into contact with the eight respective pads described above in the pressure detection element154of the semiconductor type pressure detection device150exposed inside the base110, and the temperature correction operation (trimming operation) for the pressure detection element154is performed (temperature correction process).

In more detail, intensity of a signal output from the signal output pad or the adjustment pad is read in a state in which load is applied to the pressure detection element154at a reference temperature (for example, room temperature), and a correlation between signal intensity values for respective predetermined loads is obtained to set a correction factor.

Finally, while the diaphragm130is interposed between the receiving member120and the ring member140, and a liquid medium is injected into the pressure receiving space S1formed between the base110and the diaphragm130, an overlapping portion between the receiving member120and the ring member140is continuously subjected to girth welding in an outer circumferential direction to integrate the receiving member120and the ring member140as described above (integration process).

In this instance, fusion welding such as laser welding or arc welding, or resistance welding such as seam welding may be applied to a girth welding scheme. However, it is preferable to apply laser welding, electron beam welding, etc. having a small heat input in consideration of a reduction in distortion due to welding.

FIG. 2is a longitudinal sectional view of a pressure sensor in which the pressure detection unit according to Embodiment 1 of the invention illustrated inFIGS. 1A and 1Bis installed.

As illustrated inFIG. 2, a pressure sensor1includes the pressure detection unit100according to Embodiment 1 of the invention illustrated inFIGS. 1A and 1B, a cylindrical cover10attached to the pressure detection unit100, a relay board20to which the one ends of the three terminal pins160,162, and164protruding from the pressure detection unit100are attached, a connector22attached to the relay board20, a lead wire24connected to the connector22to exchange an electrical signal, etc. with external equipment, and a fluid inlet pipe30attached to the receiving member120of the pressure detection unit100.

The cover10is a member having a stepped cylindrical shape including a large diameter portion12and a small diameter portion14, and is attached to the pressure detection unit100from the base110side in a mode in which the large diameter portion12encloses an outer circumferential portion of the pressure detection unit100.

As illustrated inFIG. 2, an inner space S3, which uses the base110as a bottom surface, is formed inside the cover10, and the relay board20and the connector22described below are accommodated in the inner space S3.

The inner space S3formed inside the cover10is filled with a resin R1, and the resin R1is solidified. Further, an opening end side of the large diameter portion12is filled with a resin R2in a mode in which the pressure detection unit100is covered with the resin R2, and the resin R2is solidified.

These resins R1and R2prevent water, etc. from penetrating into the cover10to protect an electric system of the relay board20, etc.

The relay board20is formed as a baking board, a glass epoxy board, a ceramic board, or a flexible board, one end of the connector22is attached to a central portion of the relay board20, and a via electrode and a metal wiring layer (not illustrated) are included around a position at which the connector22is attached to the central portion.

The one end of the connector22is attached to the relay board20, and the lead wire24extending to an outside of the cover10is attached to the other end of the connector22.

In addition, each of the one ends of the three terminal pins160,162, and164protruding from the base110of the pressure detection unit100penetrates a via electrode of the relay board20and is anchored to the via electrode.

In this instance, the three terminal pins160,162, and164are electrically anchored and connected to the via electrode using, for example, soldering.

For example, the fluid inlet pipe30is a pipe-shaped member made of a metal material such as a copper alloy, an aluminum alloy, etc. and includes an attachment portion32attached to the receiving member120of the pressure detection unit100and a connection portion34connected to a pipe through which a fluid subjected to pressure detection flows.

The attachment portion32is attached to the opening123of the receiving member120illustrated inFIGS. 1A and 1Busing an arbitrary scheme such as welding, adhesion, mechanical fastening, etc.

When the pressure sensor1illustrated inFIG. 2is assembled, first, the relay board20, to which the connector22is attached, is anchored to the one ends of the three terminal pins160,162, and164protruding from the base110of the pressure detection unit100.

Meanwhile, the attachment portion32of the fluid inlet pipe30is attached and fixed to the opening123of the receiving member120of the pressure detection unit100.

Subsequently, the pressure detection unit100is inserted into the large diameter portion12of the cover10such that the lead wire24is exposed to the outside through the small diameter portion14by being inserted from the large diameter portion12.

Thereafter, the resin R1is injected from the opening of the cover10on the small diameter portion14side, and the resin R1is solidified, thereby sealing the inner space S3.

Similarly, the resin R2is injected from an opening end on the large diameter portion12side, and the resin R2is solidified, thereby fixing the pressure detection unit100inside the cover10.

In the pressure sensor1illustrated inFIG. 2, the fluid subjected to pressure detection and introduced to the fluid inlet pipe30enters the pressurization space S2of the pressure detection unit100, and deforms the diaphragm130at a pressure thereof.

When the diaphragm130is deformed, the liquid medium inside the pressure receiving space S1is pressurized, and the pressure at which the diaphragm130is deformed is delivered to the pressure detection element154of the semiconductor type pressure detection device150.

The pressure detection element154detects a change in the delivered pressure, converts the change into an electrical signal, and outputs the electrical signal to the relay board20through the signal output terminal pin164.

Then, the electrical signal is delivered to a wiring layer of the relay board20, and outputs to external equipment through the connector22and the lead wire24.

When these configurations are included, the base110to which the semiconductor type pressure detection device150is attached is formed using the ceramic material whose thermal expansion coefficient is small in the pressure detection unit100according to the embodiment of the invention and the pressure sensor1to which the pressure detection unit100is applied, and thus it is possible to inhibit the base110from expanding or contracting at the time of assembling and manufacturing the pressure detection unit100or due to a change in thermal environment in which the pressure sensor1is used.

Therefore, even when the trimming operation is performed in a stage in which the semiconductor type pressure detection device150is attached to the base110, since expansion or contraction of the base110in a heat input of brazing, etc. in the assembly operation thereafter may be ignored, the trimming operation may be performed during the assembly operation before a base joining process using a simple structure.

Further, when the base110is formed using the ceramic material whose thermal expansion coefficient is small, and the number of terminal pins160,162, and164is set to three, a transfer path of common mode noise transferred from a pipe, etc. may be minimized. Thus, it is possible to reduce a decrease in detection accuracy resulting from detection of noise by the semiconductor type pressure detection device150.

In addition, when the base110is formed using the ceramic material whose thermal expansion coefficient is small, a change in shape or dimensions of the base110is small even in a case in which the base110is exposed to a touch usage environment of a high temperature or a low temperature when compared to a conventional base made of a metal material. Thus, it is possible to suppress a decrease in detection accuracy due to a thermal environment of the semiconductor type pressure detection device150.

In addition, when the base110is formed using the ceramic material, a hermetic seal made of glass, which is used when a terminal pin is buried in a base in a pressure detection unit having a conventional type, may be replaced by a brazing portion. Thus, it is possible to prevent a fragile hermetic seal portion from being damaged to prevent the liquid medium that fills the pressure receiving space from leaking.

Further, the pressure detection unit100according to the embodiment of the invention and the pressure sensor1to which the pressure detection unit100is applied form the pressure receiving structure in which the receiving member120, the diaphragm130, and the ring member140are integrated by interposing the diaphragm130between the receiving member120and the ring member140in advance, and have a structure in which the base110is joined to the ring member140of the pressure receiving structure. Thus, the diaphragm130, which is a thin plate and relatively weak, may be reinforced by the receiving member120and the ring member140.

In addition, when the base110is joined to the pressure receiving structure, only positioning between the base110and the ring member140may be performed. Thus, it is possible to simplify a joining operation, and to improve shape accuracy of the pressure detection unit100.

FIGS. 3A and 3Billustrate an outline of a pressure detection unit according to Embodiment 2 of the invention.FIG. 3Aillustrates a top view of the pressure detection unit, andFIG. 3Billustrates a cross section taken along A-A line ofFIG. 3Ain side view.

As illustrated inFIGS. 3A and 3B, the pressure detection unit200according to Embodiment 2 of the invention includes a base210made of ceramic, a receiving member220facing the base210, a diaphragm230and a ring member240interposed between the base210and the receiving member220, and a caulking member280that integrally fixes the base210and the receiving member220from an outer circumferential side.

Similarly to Embodiment 1, the base210is a circular lid-shaped member in top view, and includes a ceramic material having an insulating property in which an outer circumferential portion212and an inner portion214having a smaller thickness than that of the outer circumferential portion212are integrated with each other as illustrated inFIG. 3B. That is, the base210has a shape in which a central portion thereof is recessed such that a pressure receiving space S1described below is formed.

In addition, a ring-shaped notch portion212a, which is open in an outer circumferential direction, is formed at a lower end of the outer circumferential portion212, and a sealing member282such as an O-ring described below is attached to the notch portion212a.

The pressure receiving space S1is formed between the inner portion214of the base210and the diaphragm230, and filled with a liquid medium having an insulating property such as oil.

In addition, a semiconductor type pressure detection device250described below is installed at a central portion on the pressure receiving space S1side in the inner portion214of the base210.

As illustrated inFIG. 3A, a plurality of through-holes (see reference numeral216ofFIG. 3B) into which the three terminal pins260,262, and264are inserted is formed at positions around the semiconductor type pressure detection device250in the base210.

Further, the three terminal pins260,262, and264penetrate the base210by being inserted into the plurality of through-holes216, and one ends thereof are electrically connected to the semiconductor type pressure detection device250.

Similarly to Embodiment 1, for example, the receiving member220is formed using a metal material such as a stainless steel plate, is a plate-shaped member subjected to press molding such that a central portion is recessed, and includes a cylindrical portion221having a bottom and a cylindrical shape and a flange portion222formed at an upper end of the cylindrical portion221(the receiving member220may be formed by cutting, etc. other than press molding).

An opening223for installing a fluid inlet pipe is formed on a bottom surface of the cylindrical portion221, and the diaphragm230is joined to an upper surface of the flange portion222.

According to this configuration, a pressurization space S2into which a fluid to be detected flows is formed between the receiving member220and the diaphragm230.

Similarly to Embodiment 1, the diaphragm230is formed as a disc-shaped thin plate member made of a metal material, and the ring member240is formed as a ring-shaped member made of a metal material.

Further, the diaphragm230is subjected to girth welding while being interposed between the receiving member220and the ring member240. In this way, the receiving member220, the diaphragm230, and the ring member240are integrated to form a pressure receiving structure.

Similarly to Embodiment 1, the semiconductor type pressure detection device250includes a support substrate252made of glass and a pressure detection element (semiconductor chip)254joined to the support substrate252, and is die-bonded to the central portion of the base210using adhesion, etc.

The pressure detection element254includes a power input pad for an output signal, an earth pad, a signal output pad, and a signal adjustment pad similar to those of Embodiment 1.

As illustrated inFIG. 3A, an earth terminal pin260, a power input terminal pin262, and a signal output terminal pin264are attached to the base210by penetrating the base210using brazing.

The earth terminal pin260, the power input terminal pin262, and the signal output terminal pin264are electrically connected to the earth pad, the power input pad, and the signal output pad of the semiconductor type pressure detection device250described above through a bonding wire266.

In addition, in the semiconductor type pressure detection device250electrically connected to the three terminal pins260,262, and264attached to the base210, a temperature correction operation (trimming operation) is performed by allowing a conducting probe to come into contact with the respective pads of the pressure detection element254described above.

For example, the caulking member280is a ring-shaped member made of a metal material and disposed to surround outer circumferences of the base210and the receiving member220while the base210and the receiving member220are overlapped each other, and an upper end portion and a lower end portion thereof are integrated and fixed to each other by being subjected to plastic deformation to an inner circumferential side using a caulking device (not illustrated).

When such a configuration is employed, a degree of adhesion between the base210and the receiving member220(or the ring member240) is improved, and a structure of surrounding an outer circumferential side of an overlapping portion thereof is obtained. Thus, higher air tightness or liquid tightness may be ensured.

As an example of a procedure of assembling the pressure detection unit200according to Embodiment 2 of the invention, first, the earth terminal pin260, the power input terminal pin262, and the signal output terminal pin264are inserted into the through-holes216formed in the base210, and the three terminal pins260,262, and264and the base210are subjected to brazing to form a brazing portion (see reference symbol B3ofFIG. 3A), thereby joining and fixing the terminal pins260,262, and264to the base210(terminal pin attachment process).

In other words, similarly to Embodiment 1, a brazing material such as silver solder is interposed between the through-holes216formed in the base210and the terminal pins260,262, and264, and heating is performed at a predetermined temperature in this state, thereby forming a brazing portion B3between ceramic of the base210and metal of the terminal pins260,262, and264.

In this instance, a metallized layer (for example, a Mo—Mn layer, etc.) may be formed in advance on a surface coming into contact with the brazing material of the base210before a brazing operation is performed.

Subsequently, the semiconductor type pressure detection device250is die-bonded to the central portion of the base210.

Thereafter, the earth pad, the power input pad, and the signal output pad of the semiconductor type pressure detection device250are electrically connected to the one ends of the three terminal pins260,262, and264, respectively, through the bonding wire266(electric connection process).

Subsequently, the conducting probe is allowed to come into contact with the eight respective pads described above in the pressure detection element254of the semiconductor type pressure detection device250exposed inside the base210, and the temperature correction operation (trimming operation) for the pressure detection element254is performed (temperature correction process).

In more detail, intensity of a signal output from the signal output pad or the adjustment pad is read in a state in which load is applied to the pressure detection element254at a reference temperature (for example, room temperature), and a correlation between signal intensity values for respective predetermined loads is obtained to set a correction factor.

Subsequently, while the diaphragm230is interposed between the receiving member220and the ring member240, and the pressure receiving space S1formed between the base210and the diaphragm230is filled with a liquid medium, an overlapping portion of the receiving member220and the ring member240is continuously subjected to girth welding from an outer circumferential direction as described above (girth welding process).

In this instance, girth welding such as laser welding or arc welding, or resistance welding such as seam welding may be applied to a girth welding scheme. However, it is preferable to apply laser welding, electron beam welding, etc. having a small heat input in consideration of a reduction in distortion due to welding.

Finally, the base210is overlapped with an upper surface of the ring member240girth-welded to the receiving member220while the sealing member282such as an O-ring is attached to the notch portion212aformed at the lower end of the outer circumferential portion212of the base210, and the base210is caulked and fixed by the caulking member280and integrated with the upper surface (integration process).

In this instance, a height and a width of the sealing member282are selected such that the height and the width are slightly larger dimensions than a height and a width of the notch portion212aformed in the base210. In this way, compression is performed in a vertical direction and a left-right direction inside the notch portion212aat the time of caulking and fixing, and thus reliable air tightness and water tightness may be ensured.

FIG. 4is a longitudinal sectional view of a pressure sensor in which the pressure detection unit according to Embodiment 2 of the invention illustrated inFIG. 3is installed.

As illustrated inFIG. 4, the pressure sensor1includes the pressure detection unit200according to Embodiment 2 of the invention illustrated inFIGS. 3A and 3B, a cylindrical cover10attached to the pressure detection unit200, a relay board20to which the one ends of the three terminal pins260,262, and264protruding from the pressure detection unit200are attached, a connector22attached to the relay board20, a lead wire24connected to the connector22to exchange an electrical signal, etc. with external equipment, and a fluid inlet pipe30attached to the receiving member220of the pressure detection unit200.

Similarly to Embodiment 1, the cover10is a member having a stepped cylindrical shape including a large diameter portion12and a small diameter portion14, and is attached to the pressure detection unit200from the base210side in a mode in which the large diameter portion12encloses the caulking member280of the pressure detection unit200.

As illustrated inFIG. 4, an inner space S3, which uses the base210as a bottom surface, is formed inside the cover10, and the relay board20and the connector22described below are accommodated in the inner space S3.

The inner space S3formed inside the cover10is filled with a resin R1, and the resin R1is solidified. Further, an opening end side of the large diameter portion12is filled with a resin R2in a mode in which the pressure detection unit200is covered with the resin R2, and the resin R2is solidified.

These resins R1and R2prevent water, etc. from penetrating into the cover10to protect an electric system of the relay board20, etc.

Similarly to Embodiment 1, the relay board20is formed as a baking board, a glass epoxy board, a ceramic board, or a flexible board, and one end of the connector22is attached to a central portion of the relay board20. One end of the connector22is attached to the relay board20, and the lead wire24extending to an outside of the cover10is attached to the other end of the connector22.

In addition, each of the one ends of the three terminal pins260,262, and264protruding from the base210of the pressure detection unit200penetrates a via electrode of the relay board20and is anchored to the via electrode.

Similarly to Embodiment 1, the fluid inlet pipe30is a pipe-shaped member made of a metal material and includes an attachment portion32attached to the receiving member220of the pressure detection unit200and a connection portion34connected to a pipe through which a fluid subjected to pressure detection flows.

The attachment portion32is attached to the opening223of the receiving member220illustrated inFIG. 3Busing an arbitrary scheme such as welding, adhesion, mechanical fastening, etc.

When the pressure sensor1illustrated inFIG. 4is assembled, first, the relay board20, to which the connector22is attached, is anchored to the one ends of the three terminal pins260,262, and264protruding from the base210of the pressure detection unit200. Meanwhile, the attachment portion32of the fluid inlet pipe30is attached and fixed to the opening223of the receiving member220of the pressure detection unit200.

Subsequently, the pressure detection unit200is inserted into the large diameter portion12of the cover10such that the lead wire24is exposed to the outside through the small diameter portion14by being inserted from the large diameter portion12. Thereafter, the resin R1is injected from the opening of the cover10on the small diameter portion14side, and the resin R1is solidified, thereby sealing the inner space S3.

Similarly, the resin R2is injected from an opening end on the large diameter portion12side, and the resin R2is solidified, thereby fixing the pressure detection unit200inside the cover10.

When these configurations are included, in addition to an effect described in Embodiment 1, the pressure detection unit200according to Embodiment 2 of the invention and the pressure sensor1to which the pressure detection unit200is applied may ensure more reliable air tightness and water tightness of the pressure detection unit200since the overlapping portion of the base210and the receiving member220(or the ring member240) is not exposed by caulking, fixing, and integrating the base210and the receiving member220from the outer circumferential side using the caulking member280.

In addition, the base210and the ring member240may not be brazed, that is, the diaphragm230may be interposed between the receiving member220and the ring member240and subjected to girth welding separately from the base210, and thus it is possible to miniaturize equipment for girth welding, and to improve dimensional accuracy.

The invention is not restricted to the above respective embodiments, and various alterations may be made.

For example, Embodiment 1 describes a case in which the second brazing portion B2is formed after the first brazing portion B1is formed. However, the first brazing portion B1and the second brazing portion B2may be formed in the same process when brazing materials for forming these brazing portions have the same or substantially the same melting temperatures.

In this way, time required to manufacture the pressure sensor may be drastically reduced.

In addition, Embodiment 1 and Embodiment 2 describe that the diaphragm130(230) and the ring member140(240) are interposed between the base110(210) and the receiving member120(220). However, it is possible to employ a structure in which the diaphragm130(230) is directly interposed between the base110(210) and the receiving member120(220) without the ring member140(240) interposed therebetween by selecting an appropriate joining technology between the base110(210) made of the ceramic material and the diaphragm130(230) made of the metal material.

In this way, it is possible to reduce manufacturing cost and material of the ring member140(240), and to attempt a weight reduction of the whole pressure detection unit100(200).

In addition, Embodiment 1 and Embodiment 2 described a case in which the base110(210) and the ring member140(240) are subjected to brazing while the pressure receiving space S1formed between the base110(210) and the diaphragm130(230) is filled with the liquid medium. However, after the base110(210) and the ring member140(240) are subjected to brazing, the liquid medium may be injected from an inflow hole formed in the base110(210), and then an inlet of the inflow hole may be sealed by welding a ball thereto.

In this instance, for example, a metallized layer may be formed around the inflow hole on an outer surface of the base110(210), and the metallized layer and the ball may be subjected to resistance welding and attached to each other.

Further, Embodiment 2 describes a case in which a pressure detector is integrally fixed using the caulking member. However, it is possible to form a caulking portion that caulks and fixes the pressure detection unit200and the cover10to an outer circumferential portion of the fluid inlet pipe30that introduces the fluid subjected to pressure detection to the pressurization space S2of the receiving member220in place of a configuration of the caulking member, and to collectively integrally fix outer circumferences of the pressure detection unit200and the cover10from outer circumferential sides.

When such a configuration is employed, it is possible to reduce a process of injecting and solidifying the resin R2, and to fully accommodate the pressure detection unit200inside the cover10and the fluid inlet pipe30. Thus, water tightness may be further improved.

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