JP2014173995A - Pressure sensor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a preload applied to a sensor part while suppressing reduction in detection accuracy.SOLUTION: A metal case 20 is made to have a bottomed cylinder shape, and a diaphragm part 20b is constituted by a bottom part of the bottomed cylinder. The metal case 20 is covered with a diaphragm part 20b and exposed to a measurement medium, and includes a metal diaphragm 100 for transmitting a pressure of the measurement medium to the diaphragm part 20b. According to this constitution, a portion for supporting a preload applied from a preload applying member 30 and a portion for receiving the pressure of the measurement medium are constituted by different members. Consequently, even if a film thickness of the diaphragm part 20b is made thick so as to enable a large preload to be supported by a sensor part 50, the diaphragm part 20b is not exposed to the measurement medium, and less affected by heat distortion (temperature). Accordingly, it is possible to increase a preload applied to the sensor part 50 while suppressing reduction in detection accuracy.

Description

  The present invention relates to a pressure sensor disposed in a metal case in a state in which a preload is applied, and a method for manufacturing the same, and in particular, is attached to an automobile engine as a mounted member, It is preferably used for detecting pressure.

  Conventionally, the following pressure sensors have been proposed as this type of pressure sensor (see, for example, Patent Document 1).

  For example, this pressure sensor has a metal case with openings at both ends, a metal diaphragm is welded to one end of the metal case so as to close the opening, and a preload is provided at the other end. An application member is provided. And the sensor part comprised with a load transmission member and a piezoelectric material from the metal diaphragm side is arrange | positioned between the metal diaphragm and the preload application member in the state to which the preload was applied by the preload application member. The load transmitting member and the sensor unit are fixed by a preload and are not joined to each other.

  Such a pressure sensor is attached to the engine in a state where the metal diaphragm is exposed to the measurement medium (pressure), and is used to detect the pressure in the combustion chamber of the engine. When the metal diaphragm receives the measurement medium, a load generated on the metal diaphragm is transmitted to the sensor unit via the load transmitting member, and a sensor signal corresponding to the pressure is output from the sensor unit.

International Publication No. 2011/105084

  However, in the pressure sensor of Patent Document 1, the preload applied from the preload application member is supported by the metal diaphragm and the measurement medium is received, so that the preload cannot be increased too much. . This is because if the thickness of the metal diaphragm is increased so that a large preload can be supported, the influence of thermal distortion (temperature) of the metal diaphragm increases and the detection accuracy decreases.

  For this reason, when a sudden impact pressure due to abnormal combustion is applied to the metal diaphragm in the combustion chamber, the impact pressure causes a gap between the members such as between the metal diaphragm and the load transmission member, between the load transmission member and the sensor unit, etc. Instantaneous space (floating) may occur. In this case, there exists a problem that a sensor part may be destroyed by the collision when a load transmission member and a sensor part return to an original position.

  An object of this invention is to provide the pressure sensor which can enlarge the preload applied to a sensor part, and its manufacturing method, suppressing the fall of detection accuracy in view of the said point.

  In order to achieve the above object, in the first aspect of the present invention, a metal case (20) having a bottomed cylindrical shape having an opening, the bottom portion being a diaphragm portion (20b), and an opening side of the metal case are provided. A bonded preload application member (30), a sensor unit (50) made of a piezoelectric material and disposed in the metal case in a state in which the preload is applied from the preload application member, a diaphragm unit, and a sensor And a load transmission member (40) for transmitting the load applied to the diaphragm portion to the sensor portion. The metal case covers the diaphragm portion and is exposed to the measurement medium and is also measured by the measurement medium. The metal diaphragm (100) which transmits this pressure to a diaphragm part is provided.

  According to this, the metal case has a bottomed cylindrical shape, and the diaphragm portion supports the preload applied from the preload application member, and receives the measurement medium with the metal diaphragm. That is, the portion that supports the preload applied from the preload application member and the portion that receives the measurement medium are configured as separate members. Further, the diaphragm portion is covered with a metal diaphragm and is not exposed to the measurement medium.

  For this reason, even if the film thickness of the diaphragm part is increased so that a large preload can be supported by the sensor part, the diaphragm part is not exposed to the measurement medium, so that the influence of thermal strain (temperature) is small. Therefore, it is possible to apply a large preload to the sensor unit while suppressing a decrease in detection accuracy. As a result, even if sudden impact pressure due to abnormal combustion occurs in the combustion chamber, it is possible to suppress the occurrence of space (floating) between members such as between the load transmission member and the sensor unit, and the sensor unit is destroyed. Can be suppressed.

  A fourteenth aspect of the present invention relates to a method for manufacturing the pressure sensor according to any one of the first to thirteenth aspects, the step of sequentially arranging the load transmitting member and the sensor unit from the diaphragm side in the metal case; In the metal case, the load transmission member, the preload application member is arranged so that a predetermined preload is applied to the sensor unit, and the metal case and the preload application member are joined as they are, And a step of joining the metal diaphragm so as to cover the diaphragm portion.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is sectional drawing of the pressure sensor in 1st Embodiment of this invention. It is an enlarged view of the area | region A shown in FIG. It is sectional drawing which shows the manufacturing process of the pressure sensor shown in FIG. It is sectional drawing of the pressure sensor in 2nd Embodiment of this invention. It is sectional drawing of the pressure sensor in 3rd Embodiment of this invention. It is sectional drawing of the pressure sensor in 4th Embodiment of this invention. It is sectional drawing of the pressure sensor in other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. The pressure sensor of the present embodiment is preferably attached to, for example, an automobile engine as a member to be attached and used to detect the pressure in the combustion chamber of the engine.

  As shown in FIG. 1, the pressure sensor includes a cylindrical housing 10 having a hollow portion having openings 10 a and 10 b at both ends. The housing 10 of the present embodiment includes a cylindrical main body 11 and an elongated cylinder having an inner diameter and an outer diameter shorter than the main body 11 and a screw portion 13 that can be screwed to an attached member on an outer peripheral wall surface. And a pipe-shaped portion 12. Such a housing 10 is configured by integrally molding a metal such as SUS630 by cutting or cold forging.

  The tip of the pipe portion 12 (the opening 10a of the housing 10) is tapered so that the diameter decreases toward the tip, and the measurement medium is used when the screw portion 13 is screwed to the attached member. A pressure seal portion 14 for sealing is formed. And the metal case 20 made into the bottomed cylindrical shape which has the opening part 20a and the hollow part in the edge part of the front end side rather than the pressure seal part 14 among the pipe parts 12, and the bottom part was made into the thin-walled diaphragm part 20b. Is provided. The metal case 20 is joined to the tip end portion of the pipe portion 12 by laser welding or the like so that the hollow portion communicates with the hollow portion of the pipe portion 12.

  As shown in FIGS. 1 and 2, the metal case 20 has a preload applying member 30 disposed on the opening 20a side, and the diaphragm portion 20b is interposed between the diaphragm portion 20b and the preload applying member 30. From the side, the load transmission member 40, the sensor unit 50, the electrode 60, and the insulating member 70 are arranged in a state where a preload is applied from the preload application member 30.

  The load transmission member 40 has a tapered shape and is a cone having a trapezoidal cross section along the axial direction. And it arrange | positions so that the one surface 40a of the front end side may contact | abut with the diaphragm part 20b. Such a load transmission member 40 is configured by cutting or cold forging a metal such as SUS630.

The sensor unit 50 is a disk-shaped piezoelectric element made of a piezoelectric material such as quartz, and outputs a sensor signal (charge) according to pressure, and a metal thin film (not shown) on the front and back surfaces. Is formed. Then, and an outer diameter D _c is shorter than the outer diameter D _b of the bottom side of the load transmission member 40 is disposed on the inner edge portion of 40b (a surface facing the sensor unit 50) the bottom one surface side of the load transmitting member 40 ing. That is, the outer edge portion of the one surface 40 b on the bottom surface side of the load transmitting member 40 protrudes from the sensor portion 50 and is exposed. In the present embodiment, the front and back surfaces of the sensor unit 50 correspond to one surface facing the load transmitting member 30 of the present invention and one surface opposite to the one surface.

The electrode 60 has a shape having a convex portion 60a in a disc portion made of metal such as SUS630, and is disposed on the sensor portion 50 so that the convex portion 60a is located on the opposite side to the sensor portion 50. ing. Specifically, the outer diameter D _{d of the} disk portion is longer than the outer diameter D _{c of} the sensor unit 50, and is arranged on the inner edge portion of the one surface 60 b that faces the sensor unit 50. In other words, the outer edge portion on the one surface 60 b facing the sensor unit 50 protrudes from the sensor unit 50 and is exposed. The convex portion 60 a of the electrode 60 is electrically connected to a signal line 80 such as a copper wire via solder (not shown) or the like, and transmits a sensor signal to the signal line 80.

  The insulating member 70 insulates the electrode 60 from the preload applying member 30 and is made of alumina or the like, and has an annular shape in which a through hole 70a is formed. And it arrange | positions on the electrode 60 so that the convex part 60a may be inserted in the through-hole 70a.

  The preload application member 30 has a cylindrical shape with both ends having hollow portions and openings, and a predetermined preload is applied to the load transmission member 40, the sensor unit 50, the electrode 60, and the insulating member 70. The metal case 20 is joined by laser welding or the like. The signal line 80 is drawn into the housing 10 through the hollow portion of the preload application member 30. Note that the preload application member 30 is made of metal such as SUS630.

  In addition, a cylindrical insulating tube 90 made of polyimide or the like is disposed along the side surface in the metal case 20 to insulate the metal case 20 from the load transmission member 40, the sensor unit 50, and the electrode 60. It can be planned.

  Further, the metal case 20 is provided with a metal diaphragm 100 in which a recess 20c is formed in the outer edge of the bottom side of the outer wall surface, and a part of the metal case 100 is fitted in the recess 20c so as to cover the diaphragm 20b. It has been.

Specifically, the metal diaphragm 100 is a bottomed cylindrical shape having an opening portion is configured to bottom to generate a load in accordance with the pressure of the measurement medium, the film thickness t _a of the diaphragm portion 20b a thickness t _It is thinner than _b . And, it has a transmission part 100a projecting to the diaphragm part 20b side at a substantially central part of the bottom part, the transmission part 100a abuts on the diaphragm part 20b, and the end part on the opening part side is fitted into the concave part 20c, while the opening part The end on the side is joined to the metal case 20 by laser welding or the like. More specifically, the metal diaphragm 100 is joined to the metal case 20 so that the preload from the metal case 20 is smaller than the preload applied from the preload application member 30 to the sensor unit 50 and the like. The metal diaphragm 100 is made of a metal such as SUS630.

  As shown in FIG. 1, the connector member 120 is assembled to the opening 10 b in the housing 10 via an O-ring 110. The connector member 120 is a substantially cylindrical member made of a resin such as PPS (polyphenylene sulfide), and has a recess 120a at one end and an opening 120b at the other end. .

  The connector member 120 is integrated with the housing 10 by inserting one end of the connector member 120 into the opening 10b of the housing 10 and caulking the opening end 11a of the housing 10 on the opening 10b side.

  The connector member 120 is provided with a plurality of terminals 121, and each terminal 121 is held in the connector member 120 by being integrally formed with the connector member 120 by insert molding. Specifically, the terminal 121 is held so as to penetrate the connector member 120, and one end portion protrudes into the recess 120a and the other end portion protrudes into the opening 120b.

  Furthermore, a wiring substrate 130 made of a ceramic substrate or the like is provided at one end of the connector member 120 so as to close the recess 120a. The wiring board 130 has wiring patterns (not shown) formed on the front and back surfaces, and the wiring patterns formed on the front and back surfaces are electrically connected via electrodes (not shown) embedded in through holes. Has been.

  A control circuit 131 for amplifying and adjusting the sensor signal is mounted on the surface of the wiring board 130 (one surface on the metal case 20 side). The control circuit 131 is electrically connected to the signal line 80 drawn into the housing 10 through the hollow portion of the preload application member 30 via solder (not shown), etc. The wiring pattern formed on the surface of 130 is electrically connected via the bonding wire 132.

  One end of the terminal 121 exposed from the recess 120a is electrically connected to the wiring pattern formed on the back surface of the wiring board 130 via the solder 140, and the other end of the terminal 121 exposed from the opening 120b is These are connected to an external wiring member (not shown).

  The above is the configuration of the pressure sensor in the present embodiment. Such a pressure sensor is attached to a vehicle engine as a member to be attached by screwing the screw portion 13 and is used to detect the pressure in the combustion chamber of the engine. When pressure is applied to the metal diaphragm 100, the load generated on the metal diaphragm 100 is transmitted to the sensor unit 50 via the transmission unit 100 a, the diaphragm unit 20 b (metal case 20), and the load transmission member 40. For this reason, polarization occurs in the sensor unit 50 made of a piezoelectric material, and a sensor signal (charge) corresponding to the pressure is transmitted to the control circuit 131 via the signal line 80 to detect the pressure. The diaphragm portion 20b is covered with the metal diaphragm 100 and is not exposed to the measurement medium.

  Next, a method for manufacturing the pressure sensor will be described with reference to FIG. First, as shown in FIG. 3A, the insulating tube 90 is disposed in the metal case 20, and the load transmitting member 40, the sensor unit 50, the electrode 60, and the insulating member 70 are sequentially disposed from the diaphragm portion 20b side. To do. In this step, the load transmission member 40, the sensor unit 50, the electrode 60, and the insulating member 70 are only laminated in order, and are not fixed.

  Next, as shown in FIG. 3B, the preload application member 30 is lightly press-fitted from the opening 20 a side of the metal case 20, and the load transmission member 40, the sensor unit 50, the electrode 60, and the insulating member 70 are predetermined. In this state, the metal case 20 and the preload application member 30 are joined by laser welding or the like.

  Subsequently, as shown in FIG. 3C, the end of the opening side of the metal diaphragm 100 is fitted into the recess 20 c of the metal case 20, and the preload from the metal case 20 is applied from the preload application member 30. The metal diaphragm 100 is joined to the metal case 20 while adjusting so as to be smaller than the preload applied to the sensor unit 50 and the like.

  Thereafter, although not particularly illustrated, the pressure sensor is manufactured by joining the metal case 20 to the tip of the pipe portion 12 by laser welding or the like and assembling the connector member 120 to the housing 10.

As described above, in the present embodiment, the metal case 20 has a bottomed cylindrical shape, supports the preload applied from the preload application member 30 by the diaphragm portion 20b, and is measured by the metal diaphragm 100. The medium is received. That is, the part that supports the preload applied from the preload application member 30 and the part that receives the pressure of the measurement medium are configured as separate members. Further, the diaphragm portion 20b is not exposed to the measurement medium because they are covered with metal diaphragm 100, the thickness t _a of the metal diaphragm 100 exposed to the measurement medium, than the thickness t _a of the diaphragm portion 20b It is thinned.

Therefore, even when increasing the thickness t _b of the diaphragm portion 20b so as to be able to support a large preload to the sensor unit 50, since the diaphragm portion 20b is not exposed to the measurement medium, is less affected heat distortion (temperature). Further, the metal diaphragm 100 exposed to the measurement medium also, the film thickness t _a are thinner than the thickness t _a of the diaphragm portion 20b, a small effect of thermal strain (temperature).

  Therefore, a large preload can be applied to the sensor unit 50 while suppressing a decrease in detection accuracy. Thereby, even if a sudden impact pressure due to abnormal combustion occurs in the combustion chamber, it is possible to suppress the occurrence of a space (floating) between members such as between the load transmission member 40 and the sensor unit 50. 50 can be prevented from being destroyed.

  Further, since the metal case 20 has a bottomed cylindrical shape, even if the metal diaphragm 100 is peeled off from the metal case 20, the load transmission member 40, the sensor unit 50, the electrode 60, the insulating member 70, and the insulating tube 90 are made of metal. It can suppress falling out of the case 20.

  Furthermore, the metal diaphragm 100 is joined to the metal case 20 while the end on the opening side is fitted in the recess 20c. For this reason, position shift with the metal case 20 and the metal diaphragm 100 can be suppressed, and the load which generate | occur | produced in the metal diaphragm 100 can be efficiently transmitted to the diaphragm part 20b.

The metal diaphragm 100 is joined to the metal case 20 so that the preload from the metal case 20 is smaller than the preload applied from the preload application member 30 to the sensor unit 50 and the like. Therefore, it reduce the film thickness t _a of the metal diaphragm 100, it is possible to further reduce the influence of thermal strain (temperature).

Further, the load transmission member 40, the sensor unit 50, the electrode 60, the relationship of the outer _diameter, D _b, is a D d> _{D c,} one surface 60b of one surface 40b and the electrode 60 of the load transmission member 40 is exposed . That is, one surface 40 b of the load transmission member 40 and one surface 60 b of the electrode 60 protrude from the sensor unit 50. For this reason, it is set as _Db , _Dd < _Dc , and compared with the case where the outer edge part of the sensor part 50 protrudes from the load transmission member 40 and the electrode 60, it is from the load transmission member 40 and the electrode 60 to the sensor part 50. A uniform load can be applied, and the occurrence of stress concentration at the outer edge of the sensor unit 50 can be suppressed.

Further, the load transmitting member 40 is a cone having a trapezoidal cross section along the axial direction, the one surface 40 a at the tip side is in contact with the diaphragm portion 20 b, and the one surface 40 b is in contact with the sensor portion 50. Yes. For this reason, the freedom degree of design can be improved. In other words, in the pressure sensor as described above, a large stress is likely to be generated in the metal case 20 at the connecting portion between the bottom portion and the side surface of the metal case 20. Further, as described above, it is preferable that the outer diameters of the load transmission member 40 and the sensor unit 50 satisfy D _b > D _c . For this reason, when the load transmission member 40 has a cylindrical shape that satisfies D _b > D _c , the connection portion between the bottom portion and the side surface of the metal case 20 and the load transmission member 40 are too close to each other, and therefore the influence of the stress of the connection portion. However, the design flexibility can be improved by forming the load transmission member 40 in the above-described shape.

  A metal thin film is formed on the front and back surfaces of the sensor unit 50. For this reason, stable charge transfer to the electrode 60 can be realized, and stable load transfer can be realized by absorbing undulations on the front and back surfaces of the sensor unit 50.

  A pressure seal portion 14 is formed between the screw portion 13 and the joint portion of the metal case 20 in the housing 10. For this reason, compared with the case where the pressure seal part 14 is formed in the metal case 20, it can suppress that the metal case 20 peels from the housing 10. FIG. That is, when the pressure sensor is attached to the attached member by screwing, the tightening torque is generated between the screw portion 13 and the pressure seal portion 14. Therefore, when the pressure seal portion 14 is formed on the metal case 20, a tightening torque is applied to the welded portion (joint portion between the housing 10 and the metal case 20) between the screw portion 13 and the pressure seal portion 14 so that the housing The metal case 20 may be peeled off from the housing 10, but by forming the seal portion 14 between the screw portion 13 and the joint portion of the metal case 20 in the housing 10, the metal case 20 is removed from the housing 10. Can be prevented from peeling.

  Furthermore, in the present embodiment, when the pressure sensor is manufactured, the preload applying member 30 is lightly press-fitted into the metal case 20 and the preload is applied to the sensor unit 50 and the like, so that a stable load transmission surface can be formed. .

(Second Embodiment)
A second embodiment of the present invention will be described. In the present embodiment, the configuration of the load transmission member 40 is changed with respect to the first embodiment, and the other aspects are the same as those of the first embodiment, and thus the description thereof is omitted here.

  As shown in FIG. 4, in the present embodiment, a contact portion 20 d that protrudes toward the metal case 20 is provided at a substantially central portion of the diaphragm portion 20 b opposite to the load transmission member 40 side. Specifically, the contact portion 20d has a side surface that is parallel to the protruding direction, and a connecting portion with the diaphragm portion 20b is inclined with respect to the side surface and the surface direction of the diaphragm portion 20b. And in the cross section in the direction orthogonal to the protruding direction, the step area of the connecting portion with the diaphragm portion 20b is made larger than the cross-sectional area on the leading end side in the protruding direction. In the present embodiment, the connecting portion between the contact portion 20d and the diaphragm portion 20b is a so-called R surface. In FIG. 4, the connection portion between the contact portion 20 d and the diaphragm portion 20 b is illustrated as an R surface, but the connection portion between the contact portion 20 d and the diaphragm portion 20 b is a so-called C surface. May be.

  The metal diaphragm 100 is disposed in the metal case 20 so that the transmission part 100a contacts the contact part 20d, and the load is transmitted to the diaphragm part 20b via the contact part 20d and the transmission part 100a. It has become. 4 corresponds to an enlarged view of region A in FIG.

  According to this, in the diaphragm part 20b, the largest stress is generated in the connection part between the contact part 20d and the diaphragm part 20b. For this reason, compared with the case where the diaphragm part 20b contacts the transmission part 100a directly, the location which contacts the load transmission member 40 among the diaphragm parts 20b becomes difficult to bend, and the diaphragm part 20b and the load transmission member 40 are stable. Contact can be secured.

  Moreover, since the location where the largest stress is generated is provided by providing the contact portion 20d, the size of the preload can be determined according to the requirements of the location, and the degree of freedom in design can be improved.

  Furthermore, the counter torque is easily generated by providing the contact portion 20d. For this reason, for example, even if the thickness of the side surface of the metal case 20 is partially different, the diaphragm portion with respect to a plane whose normal direction is the axial direction of the metal case 20 (the vertical direction in FIG. 2) 20b can be prevented from being tilted by the preload, and stable contact with the load transmitting member 40 can be ensured.

  And since the contact part 20d makes the connection part with the diaphragm part 20b into the R surface (C surface), although the largest stress generate | occur | produces in a connection part, it can make a maximum stress small.

(Third embodiment)
A third embodiment of the present invention will be described. The present embodiment is different from the second embodiment in the shapes of the contact portion 20d and the transmission portion 100a, and the other aspects are the same as those of the second embodiment, and thus the description thereof is omitted here.

  As shown in FIG. 5, in the present embodiment, the abutting portion 20 d and the transmission portion 100 a each have a curved tip surface in the protruding direction. The contact portion 20d and the transmission portion 100a are in Hertz contact with each other. FIG. 5 corresponds to an enlarged view of the area A in FIG.

  According to this, compared with the case where the diaphragm part 20b and the metal diaphragm 100 are surface-contacting, the transmissibility of the load from the transmission part 100a to the contact part 20d can be improved.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. In the present embodiment, the configuration of the load transmission member 40 is changed with respect to the first embodiment, and the other aspects are the same as those of the first embodiment, and thus the description thereof is omitted here.

  As shown in FIG. 6, in the present embodiment, a load transmission member 40 is provided in a substantially middle portion of the diaphragm portion 20 b, and the metal case 20 and the load transmission member 40 are integrated. Such a metal case 20 is configured by integrally molding a metal such as SUS630 by cutting or cold forging. FIG. 6 corresponds to an enlarged view of region A in FIG.

  According to this, compared with the case where the metal case 20 and the load transmission member 40 are separate members, the portion of the load transmission member 40 that contacts the sensor unit 50 is less likely to bend, and the diaphragm 20b and the load Stable contact with the transmission member 40 can be ensured. In addition, the number of parts can be reduced.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims.

  For example, as shown in FIG. 7, the transmission part 100 a is not provided in the metal diaphragm 100, and the contact part 20 d of the second embodiment is provided in the diaphragm part 20 b so as to contact the metal diaphragm 100, The load may be transmitted to the diaphragm portion 20b through the contact portion 20d. FIG. 7 corresponds to an enlarged view of the area A in FIG.

In the first embodiment, the load transmission member 40, the sensor unit 50, the relationship of the outer diameter of the electrode _60, D _b, or may be a _D d <D _c. The metal diaphragm 100 may be joined to the metal case 20 so that the preload from the metal case 20 is equal to or greater than the preload applied from the preload application member 30 to the sensor unit 50 or the like. Furthermore, in the said 2nd, 3rd embodiment, the connection part of 20 d of contact parts and the diaphragm part 20b may be perpendicular | vertical with respect to the surface direction of the diaphragm part 20b. And in the said 1st-4th embodiment, if the predetermined clearance gap is formed between the load transmission member 40, the sensor part 50, the electrode 60, and the side surface of the metal case 20, and insulation can be ensured, it is an insulation tube. 90 may not be provided. Even in such a configuration, the effect of the present invention can be obtained by providing the metal diaphragm 100 covering the diaphragm portion 20b.

  Furthermore, in each said embodiment, the load transmission member 40 does not need to be a cone, and may be a pyramid. Similarly, the sensor unit 50 may have a rectangular plate shape, and the electrode 60 may have a shape having a convex portion 60a on the rectangular plate portion.

  The above embodiments can be combined. For example, the metal case 20 and the load transmission member 40 may be integrated by combining the fourth embodiment with the second and third embodiments.

DESCRIPTION OF SYMBOLS 20 Metal case 20a Opening part 20b Diaphragm part 30 Preload application member 40 Load transmission member 50 Sensor part 100 Metal diaphragm

Claims (17)

A metal case (20) having a bottomed cylindrical shape having an opening (20a), the bottom being a diaphragm (20b);
A preload application member (30) joined to the opening side of the metal case;
A sensor unit (50) made of a piezoelectric material and disposed in the metal case in a state in which a preload is applied from the preload application member;
A load transmission member (40) disposed between the diaphragm portion and the sensor portion and configured to transmit a load applied to the diaphragm portion to the sensor portion;
The metal case is provided with a metal diaphragm (100) that covers the diaphragm portion, is exposed to the measurement medium, receives the measurement medium, and transmits the load to the diaphragm portion. Pressure sensor. 2. The pressure sensor according to claim 1, wherein _a film thickness (t _a ) of a portion of the metal diaphragm that receives the measurement medium is made thinner than a film thickness (t _b ) of the diaphragm portion. The metal diaphragm has a bottomed cylindrical shape having a bottom portion that generates the load according to the pressure of the measurement medium, and has a transmission portion (100a) that protrudes toward the diaphragm portion on the bottom portion,
The pressure sensor according to claim 1, wherein the load is transmitted from the transmission unit to the diaphragm unit. The metal case is formed with a recess (20c) at the outer edge on the bottom side of the outer wall surface,
The pressure sensor according to claim 3, wherein the metal diaphragm is provided in the metal case while an end portion on an opening side is fitted in the concave portion. The diaphragm portion has a contact portion (20d) that protrudes toward the bottom side of the metal diaphragm and contacts the transmission portion;
5. The pressure sensor according to claim 3, wherein the load is transmitted to the diaphragm portion through the transmission portion and the contact portion.   6. The pressure sensor according to claim 5, wherein the transmitting portion and the abutting portion each have a curved tip surface in the protruding direction and are in hertz contact with each other.   The contact portion has a side surface parallel to the protruding direction, and a connecting portion with the diaphragm portion is inclined with respect to the surface direction of the side surface and the diaphragm portion, and is in a direction orthogonal to the protruding direction. The pressure sensor according to claim 5 or 6, wherein in the cross section, the step area of the connecting portion is larger than the cross-sectional area at the front end side in the protruding direction.   The load transmitting member has one surface (40b) that contacts the sensor portion, and an inner edge portion of the one surface contacts the sensor portion and an outer edge portion protrudes from the sensor portion and is exposed. The pressure sensor according to any one of claims 1 to 7.   9. The load transmitting member according to claim 1, wherein the load transmitting member is a cone whose area in contact with the diaphragm is smaller than the area in contact with the sensor. The pressure sensor described in 1. Between the sensor part and the preload application member, an electrode (60) electrically connected to the sensor part is disposed,
The electrode has one surface (60b) in contact with the sensor portion, an inner edge portion of the one surface is in contact with the sensor portion, and an outer edge portion protrudes from the sensor portion and is exposed. Item 10. The pressure sensor according to any one of Items 1 to 9.   The preload applied to the metal diaphragm from the metal case is made smaller than the preload applied to the sensor unit from the preload application member. The pressure sensor described in 1.   The pressure sensor according to any one of claims 1 to 11, wherein the sensor unit includes a metal thin film formed on one surface facing the load transmitting member and one surface opposite to the one surface.   The pressure sensor according to claim 1, wherein the diaphragm portion and the load transmission member are integrated. It has a cylindrical shape having an opening (10a), and includes a housing (10) to which the metal case is joined at an end on the opening side.
The housing is formed with a screw portion (13) that is screw-coupled to the attached member, and a gap between the attached portion and the screw portion between the metal case and the attached member. The pressure sensor according to any one of claims 1 to 13, wherein a pressure seal portion (14) for sealing is formed. In the manufacturing method of the pressure sensor according to any one of claims 1 to 14,
Arranging the load transmitting member and the sensor part in order from the diaphragm part side in the metal case;
Placing the preload application member on the metal case so that a predetermined preload is applied to the load transmitting member and the sensor unit, and joining the metal case and the preload application member as they are;
And a step of joining the metal diaphragm to the metal case so as to cover the diaphragm portion.   In the step of joining the metal diaphragm, the metal diaphragm is joined to the metal case so that a preload applied from the metal case is smaller than a preload applied from the preload application member to the sensor unit. The method of manufacturing a pressure sensor according to claim 15. 16. The step of disposing the preload application member includes lightly press-fitting the preload application member into the metal case and applying the predetermined preload to the load transmission member and the sensor unit. Or the manufacturing method of the pressure sensor of 16.

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