JP2021051025A - Manufacturing method for pressure detector - Google Patents

Abstract

To suppress the breakage of a piezoelectric element in manufacturing a pressure detector that includes the piezoelectric element.SOLUTION: Against a temporary assembly created by assembling the constituent member of a second structure that includes a diaphragm head 32 and a pressing member 49 and a tip insulating member 43 that constitutes a fourth structure, the pressing member 49 is pushed by a piston 620 inserted from a rear end side and the diaphragm head 32 is pushed via the tip insulating member 43, to set up these. Thereafter, a first internal housing 35 and a second internal housing 36 are integrated together via a second welding part W2 to obtain the second structure. Next, a third structure (piezoelectric module 400) including a piezoelectric element 41 and a support member 53 are inserted from the rear end side into the second structure having the tip insulating member 43 attached thereto, and the second internal housing 36 and the support member 53 are integrated together via a third welding part W3 while a prescribed preload is added to the piezoelectric element 41 via the support member 53, to obtain the fourth structure.SELECTED DRAWING: Figure 18

Description

The present invention relates to a method for manufacturing a pressure detector.

As a pressure detecting device for detecting the pressure in a combustion chamber of an internal combustion engine or the like, a device using a piezoelectric element having piezoelectricity has been proposed.

Patent Document 1 describes a tubular housing, a diaphragm provided on the front end side of the housing, and a piezoelectric structure provided in the housing in the axial direction on the rear end side of the diaphragm and detecting a pressure acting through the diaphragm. A pressure transmission unit and a pressure transmission unit that are provided in contact with the piezoelectric element between the element and the diaphragm and the piezoelectric element in the axial direction in the housing and transmit the pressure acting through the diaphragm to the piezoelectric element. Described is a pressure detecting device comprising a pressurizing member that applies a load to the piezoelectric element by being fixed to the housing so as to pressurize in the axial direction of the housing.

Further, in Patent Document 2, a housing unit including an outer cylinder portion forming an outer peripheral surface and an inner cylinder portion forming an inner peripheral surface of the combustion pressure sensor, and a housing unit provided in front of the housing unit on the combustion chamber side, the front surface thereof is provided. A pressure receiving ring block portion that serves as a pressure receiving surface, a plurality of piezoelectric elements that are arranged in the housing unit to detect the pressure from the pressure receiving ring block portion, and a support ring block portion that is provided behind the housing unit and supports the piezoelectric element. In the manufacturing method of the combustion pressure sensor provided with the preload means for applying the preload to the piezoelectric element, the preload adjustment for adjusting the preload applied to the piezoelectric element by sliding the support ring block portion in the pressure axis direction. It has a step and a fixing step of fixing the support ring block portion to the housing unit after adjusting the preload, and the preload adjustment step has a setting process step of setting the pressure receiving portion of the pressure receiving ring block portion. It is stated that it is doing.

Japanese Unexamined Patent Publication No. 2013-205307 Japanese Unexamined Patent Publication No. 2014-163919

However, a method of setting the pressure member that applies a load to the piezoelectric element by using the piezoelectric element itself, in other words, applying a force necessary for plastically deforming the pressure member to the piezoelectric element. When the method was adopted, there was a concern that the piezoelectric element would be damaged due to the excessive force applied to the piezoelectric element.
An object of the present invention is to suppress damage to the piezoelectric element in the manufacture of a pressure detection device including the piezoelectric element.

The present invention includes a piezoelectric element that outputs an electric signal corresponding to a pressure received from the outside along the axial direction, and a spring member that has elasticity and applies a pressing force along the axial direction to the piezoelectric element. This is a method of manufacturing a pressure detection device, in which a pressing member that applies a pressing force from the other end side in the axial direction toward one end side is pressed against the one end side of the spring member to set the spring member. It includes a setting step and an imparting step of applying the pressing force to the piezoelectric element by using the spring member by positioning the piezoelectric element and the set spring member.
In the method of manufacturing such a pressure detecting device, the spring member sandwiches the piezoelectric element from the one end side and the other end side to impart a preload as the pressing force to the piezoelectric element. It can be characterized by being a pressurizing member that pressurizes the piezoelectric element.
Further, the pressurizing member has a tubular shape by providing a through hole along the axial direction, and in the setting step, the pressing member is inserted into the through hole in the pressurizing member. In this state, the pressing member may be brought into contact with the inner peripheral surface of the pressing member on one end side.
Further, in the applying step, the pressing member is pulled out from the inside of the through hole in the pressurizing member, and the piezoelectric element is housed inside the through hole, and the pressurizing member is used to use the pressurizing member on one end side. The piezoelectric element can be sandwiched from the other end side.
Further, in the applying step, the one end side of the piezoelectric element is abutted against the inner peripheral surface of the pressurizing member, and the other end side of the piezoelectric element is abutted against the abutting member. Later, it can be characterized by further including a fixing step of fixing the pressurizing member and the abutting member in a state where the preload is applied to the piezoelectric element.
Further, the spring member may be a pressure receiving member provided on one end side of the piezoelectric element and receiving a pressure transmitted to the piezoelectric element from the outside.
Further, in the setting step, a pressure transmitting member for transmitting the pressure received by the pressure receiving member to the piezoelectric element is arranged on the rear end side of the pressure receiving member, and the pressing member is brought into contact with the pressure transmitting member. It can be characterized in that the pressure receiving member is pushed from the pressing member via the pressure transmitting member.
Further, in the applying step, the pressing member is removed from the other end side of the pressure receiving member, and the pressure transmitting member and the piezoelectric element are arranged in this order on the other end side of the pressure receiving member. The piezoelectric element can be sandwiched between the one end side and the other end side by using a pressure receiving member.
Further, the magnitude of the pressing force applied in the applying step may be smaller than the magnitude of the pressing force applied by the pressing member in the setting step.
From another point of view, in the method of manufacturing the pressure detection device of the present invention, a pressurizing member extending along the axial direction from one end side to the other end side is arranged, and the pressurizing member is arranged on the one end side. In addition, an arrangement step of arranging a pressure receiving member that receives pressure from the outside and a pressing member that applies a pressing force from the other end side toward the one end side are provided on the one end side of the pressing member and the other of the pressure receiving member. Using the pressurizing member, a double setting step of setting both the pressurizing member and the pressure receiving member by pressing against the end side and a piezoelectric element that outputs an electric signal corresponding to the pressure received from the outside are used. The preload applying step of applying a preload to the piezoelectric element by sandwiching it from the one end side and the other end side, and the pressure receiving member and the piezoelectric element to which the preload is applied can be directly or otherwise. It includes a positioning step of positioning the piezoelectric element by indirectly contacting the piezoelectric element via the member.
In the method of manufacturing such a pressure detecting device, in the double setting step, the pressing member first presses against the pressure member, and then presses against the pressure receiving member. Can be.
Further, the pressure member and the pressure receiving member may be made of the same material.
Further, the magnitude of the force corresponding to the preload applied in the preload applying step may be smaller than the magnitude of the pressing force applied by the pressing member in the double setting step. ..
Further, the piezoelectric element can be characterized by having a piezoelectric body made of an inorganic single crystal.
Further, the piezoelectric material can be characterized by being a Langasite-based single crystal.

According to the present invention, it is possible to suppress damage to the piezoelectric element in the manufacture of the pressure detection device including the piezoelectric element and in the manufacture of the pressure detection device including the piezoelectric element.

It is a schematic block diagram of the pressure detection system which concerns on embodiment. It is a side view of the pressure detection device. It is sectional drawing (III-III sectional view of FIG. 2) of the pressure detection apparatus. It is an enlarged sectional view of the tip side (IV region of FIG. 3) of a pressure detection device. FIG. 5 is an exploded cross-sectional view of a first internal housing, a second internal housing, a pressurizing member, a first insulating member, and a second insulating member constituting the pressure detection device. (A) is a perspective view of a first accommodating member provided in the pressure detecting device, and (b) is a perspective view of a second accommodating member provided in the pressure detecting device. It is a perspective view of the circuit built-in member provided in the pressure detection device. It is a schematic block diagram of the circuit board provided in the circuit built-in member. (A) is a top view of the piezoelectric module provided in the pressure detection device, and (b) is a cross-sectional view of IXB-IXB of (a). It is a figure for demonstrating the manufacturing procedure of a pressure detection apparatus. It is a figure which shows the schematic structure of the setting apparatus. (A) and (b) are diagrams for explaining the structure of the piston provided in the setting device. It is a flowchart which shows the manufacturing procedure of the 2nd structure. It is sectional drawing which shows the structure of the 1st structure used in the "temporary assembly process" of step 10. It is sectional drawing for demonstrating "temporary assembly process" of step 10. It is a figure for demonstrating the "installation process" of step 20. It is a figure for demonstrating the "insertion process" of step 30. It is a figure for demonstrating the "pressurization process" of a step 40. It is a figure for demonstrating the "drawing process" of step 50. It is sectional drawing which shows the structure of the 2nd structure obtained through the "removal process" of a step 60 and the "welding process" of a step 70. It is sectional drawing which shows the structure of the 4th structure. (A) is a graph showing the relationship between the displacement amount of the pressurizing member and the applied load when the pressurizing member is set by itself, and (b) is the graph when the diaphragm head 32 is set by itself. , Is a graph showing the relationship between the displacement amount of the diaphragm head and the applied load. It is a graph which shows the relationship between the displacement amount of a diaphragm head, and the applied load when both a pressurizing member and a diaphragm head are set together.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[Pressure detection system configuration]
FIG. 1 is a schematic configuration diagram of the pressure detection system 1 according to the embodiment.
The pressure detection system 1 supplies power to the pressure detection device 20 for detecting the pressure (combustion pressure) in the combustion chamber C in the internal combustion engine 10 and the pressure detection device 20, and is based on the pressure detected by the pressure detection device 20. It includes a control device 100 that controls the operation of the internal combustion engine 10, and a connection cable 80 that electrically connects the pressure detection device 20 and the control device 100.

Here, the internal combustion engine 10 whose pressure is to be detected includes a cylinder block 11 in which a cylinder is formed, a piston 12 that reciprocates in the cylinder, and a combustion chamber C that is fastened to the cylinder block 11 together with the piston 12 and the like. It has a cylinder head 13 constituting the above. Further, the cylinder head 13 is provided with a communication hole 13a for communicating the combustion chamber C and the outside. Then, the pressure detecting device 20 is attached to the internal combustion engine 10 by inserting the tip side of the pressure detecting device 20 into the communication hole 13a and fixing the pressure detecting device 20 to the cylinder head 13. Here, the cylinder block 11, the piston 12, and the cylinder head 13 constituting the internal combustion engine 10 are made of a conductive metal material such as cast iron or aluminum.

[Configuration of pressure detector]
FIG. 2 is a side view of the pressure detecting device 20. Further, FIG. 3 is a cross-sectional view of the pressure detection device 20 (a cross-sectional view taken along line III-III of FIG. 2). Further, FIG. 4 is an enlarged cross-sectional view of the tip end side (IV region of FIG. 3) of the pressure detection device 20. Furthermore, FIG. 5 shows a first internal housing 35, a second internal housing 36, a pressure member 49, a first insulating member 51, and a second insulating member 52 constituting the pressure detection device 20 (for details of each, It is an exploded sectional view (described later).

The pressure detecting device 20 includes a housing portion 30 which has a tubular shape as a whole and is provided so as to be exposed to the outside, and various mechanisms for detecting pressure, and almost the entire pressure detecting device 20 is housed inside the housing portion 30. It also has a detection mechanism portion 40 provided so that a part thereof is exposed to the outside, and a seal portion 70 attached to the outer peripheral surface of the housing portion 30. Then, in the pressure detecting device 20, the left side in FIG. 2 faces the combustion chamber C (lower side in FIG. 1) and the right side in FIG. 2 faces the outside (upper side in FIG. 1) with respect to the internal combustion engine 10 shown in FIG. It is installed so that it faces. In the following description, in FIG. 2, the side toward the left in the figure is referred to as the “tip side” of the pressure detection device 20, and the side toward the right in the figure is referred to as the “rear end side” of the pressure detection device 20. Further, in the following description, the direction of the center line of the pressure detecting device 20 shown by the alternate long and short dash line in FIG. 2 and the like is simply referred to as “center line direction”.

Here, in the present embodiment, the "tip side" corresponds to the "one end side" and the "rear end side" corresponds to the "other end side". Further, in the present embodiment, the "center line direction" corresponds to the "axial direction".

(Structure of housing)
The housing portion 30 includes a tip outer housing 31, a diaphragm head 32 attached to the tip side of the tip outer housing 31, and an intermediate outer housing 33 attached to the rear end side of the tip outer housing 31. It is provided with a rear end outer housing 34 attached to the rear end side of the intermediate outer housing 33. Further, the housing portion 30 is the first inner housing 35 inside the tip outer housing 31 and attached to the rear end side of the diaphragm head 32, and the first inside inside the tip outer housing 31. It further includes a second internal housing 36 attached to the rear end side of the housing 35.

[External tip housing]
The tip outer housing 31 is a member having a hollow structure and exhibiting a tubular shape as a whole. The tip outer housing 31 is made of a metal material such as stainless steel, which has conductivity and high heat resistance and acid resistance. Examples of such a metal material include SUS630 known as precipitation hardening stainless steel and SUH660 known as austenitic heat-resistant steel (heat-resistant alloy). However, other metals or various alloys (various stainless steels, various heat-resistant steels, various heat-resistant alloys) and the like can be adopted as long as they satisfy the required characteristics.

[Diaphragm head]
The diaphragm head 32 as an example of the spring member or the pressure receiving member is a member having a disc shape as a whole. The diaphragm head 32 is made of a metal material such as stainless steel, which has conductivity and high heat resistance and acid resistance. Examples of such a metal material include SUS630 known as precipitation hardening stainless steel and SUH660 known as austenitic heat-resistant steel (heat-resistant alloy). However, other metals or various alloys (various stainless steels, various heat-resistant steels, various heat-resistant alloys, etc.) can be adopted as long as they satisfy the required characteristics. In this example, the diaphragm head 32 is made of the same material as the tip outer housing 31 (for example, SUS630).

As shown in FIG. 4, the diaphragm head 32 has a surface center recess 32b formed in the central portion on the tip side, and a pressure receiving surface (surface) that receives pressure by being exposed to the outside (combustion chamber C side). It has 32a. Further, the diaphragm head 32 has a back surface annular recess 32c formed by cutting out the back surface of the pressure receiving surface 32a in an annular shape, and the presence of the back surface annular recess 32c results in a central portion of the pressure receiving surface 32a. It has a back surface central convex portion 32d that protrudes toward the rear end side from the front surface central concave portion 32b formation portion). Further, the diaphragm head 32 has a back surface annular flat portion 32e formed by annularly cutting out a peripheral edge portion on the back surface of the pressure receiving surface 32a, and a back surface annular recess 32c and a back surface annular flat portion 32e as a result. It has a back surface annular convex portion 32f protruding from the periphery of the central convex portion 32d toward the rear end side.

The diaphragm head 32 is provided so as to close the opening on the tip side of the tip outer housing 31. More specifically, the tip side of the tip outer housing 31 abuts against the back surface annular flat portion 32e of the diaphragm head 32. Then, laser welding is applied to the boundary portion between the diaphragm head 32 and the tip outer housing 31 over the entire circumference of the outer peripheral surface.

Here, the diaphragm head 32 of the present embodiment functions as a spring by expanding and contracting the periphery of the thinnest back surface annular recess 32c in response to an external force. The diaphragm head 32 vibrates according to the pressure (external pressure) received from the combustion chamber C or the like.

[Intermediate external housing]
The intermediate outer housing 33 is a member having a hollow structure and having a tubular shape as a whole. The intermediate outer housing 33 is made of a metal material such as stainless steel, which has conductivity and high heat resistance and acid resistance. As such a metal material, for example, SUS430LX known as a ferritic stainless steel can be exemplified. However, other metals or various alloys (various stainless steels, various heat-resistant steels, various heat-resistant alloys) and the like can be adopted as long as they satisfy the required characteristics. In this example, the intermediate outer housing 33 is made of a material different from that of the tip outer housing 31 (for example, SUS430LX).

The tip end side of the intermediate outer housing 33 is fitted into the rear end side of the tip outer housing 31. Then, laser welding is applied to the boundary portion between the intermediate outer housing 33 and the tip outer housing 31 over the entire circumference of the outer peripheral surface.

[Rear end external housing]
The rear end outer housing 34 is a member having a hollow structure and exhibiting a tubular shape as a whole. The rear end outer housing 34 is made of a metal material such as stainless steel, which has conductivity and high heat resistance and acid resistance. As such a metal material, for example, SUS430LX known as a ferritic stainless steel can be exemplified. However, other metals or various alloys (various stainless steels, various heat-resistant steels, various heat-resistant alloys, etc.) can be adopted as long as they satisfy the required characteristics. In this example, the rear end outer housing 34 is made of the same material as the intermediate outer housing 33 (for example, SUS430LX).

The front end side of the rear end outer housing 34 is fitted into the rear end side of the intermediate outer housing 33. Then, laser welding is applied to the boundary portion between the rear end outer housing 34 and the intermediate outer housing 33 over the entire circumference of the outer peripheral surface.

[First internal housing]
The first internal housing 35 is a member having a hollow structure and having a tubular shape as a whole. The first inner housing 35 is made of a metal material such as stainless steel, which has conductivity and high heat resistance and acid resistance. Examples of such a metal material include SUS630 known as precipitation hardening stainless steel and SUH660 known as austenitic heat-resistant steel (heat-resistant alloy). However, other metals or various alloys (various stainless steels, various heat-resistant steels, various heat-resistant alloys, etc.) can be adopted as long as they satisfy the required characteristics. In this example, the first internal housing 35 is made of the same material as the diaphragm head 32 (for example, SUS630). Further, the first internal housing 35 and the diaphragm head 32 may be made of different materials.

As shown in FIG. 5, the first internal housing 35 has a first tip tubular portion 351 located on the most distal side and a first rear end cylinder located on the rear end side of the first tip tubular portion 351. It has a shape portion 352. In the first internal housing 35, the outer diameter of the first rear end tubular portion 352 is larger than that of the first tip tubular portion 351, and the first outer step portion 353 is provided at the boundary between the two. ing. Further, the through hole provided inside the first internal housing 35 has an inner diameter that gradually increases from the front end side to the rear end side, and is inside the first rear end tubular portion 352. A first inner step portion 354 is provided at the portion to be.

The front end side of the first internal housing 35 abuts on the rear end side of the diaphragm head 32. More specifically, the front end side surface of the first outer step portion 353 of the first inner housing 35 abuts on the rear end side surface of the back surface annular convex portion 32f of the diaphragm head 32. At this time, the first tip tubular portion 351 in the first inner housing 35 is located inside the back surface annular recess 32c in the diaphragm head 32. Then, laser welding is performed on the boundary portion between the first internal housing 35 and the diaphragm head 32 over the entire circumference of the outer peripheral surface (for details, the first welded portion W1 (see FIG. 14) described later).

[Second internal housing]
The second internal housing 36 is a member having a hollow structure and having a tubular shape as a whole. The second inner housing 36 is made of a metal material such as stainless steel, which has conductivity and high heat resistance and acid resistance. Examples of such a metal material include SUS630 known as precipitation hardening stainless steel and SUH660 known as austenitic heat-resistant steel (heat-resistant alloy). However, other metals or various alloys (various stainless steels, various heat-resistant steels, various heat-resistant alloys, etc.) can be adopted as long as they satisfy the required characteristics. In this example, the second inner housing 36 is made of the same material as the first inner housing 35 (for example, SUS630).

As shown in FIG. 5, the second internal housing 36 has a second tip tubular portion 361 located on the most distal side and a second rear end cylinder located on the rear end side of the second tip tubular portion 361. It has a shape portion 362 and a shape portion 362. In the second inner housing 36, the outer diameter of the second rear end tubular portion 362 is larger than that of the second tip tubular portion 361, and a second outer step portion 363 is formed at the boundary between the two. ing. Further, the inner diameter of the through hole provided inside the first internal housing 35 is substantially constant.

The tip end side of the second inner housing 36, that is, the tip end side of the second tip tubular portion 361 is accommodated inside the first rear end tubular portion 352 of the first inner housing 35. Further, the surface on the front end side of the second internal housing 36 abuts on the surface on the rear end side of the second insulating member 52 (details will be described later). At this time, the rear end side of the second tip tubular portion 361 and the second rear end tubular portion 362 are exposed to the rear end side of the first inner housing 35. Then, laser welding is performed on the boundary portion between the second inner housing 36 and the first inner housing 35 over the entire circumference of the outer peripheral surface (for details, see the second welded portion W2 (see FIG. 20), which will be described later. )). This laser welding can be performed, for example, by spot welding in which a plurality of laser spots having a predetermined interval are formed over the circumference of the outer peripheral surface at the boundary between the second inner housing 36 and the first inner housing 35. .. In addition, instead of spot welding, seam welding over the outer peripheral surface may be performed.

(Configuration of detection mechanism)
The detection mechanism unit 40 includes a piezoelectric element 41, a tip electrode member 42, a tip insulating member 43, a rear end electrode member 44, and a rear end insulating member 45. Further, the detection mechanism unit 40 includes a first coil spring 46, a conduction member 47, a holding member 48, a pressure member 49, and an insulating tube 50. Further, the detection mechanism unit 40 includes a first insulating member 51, a second insulating member 52, a support member 53, and a second coil spring 54. Furthermore, the detection mechanism unit 40 includes a first accommodating member 55, a second accommodating member 56, a circuit built-in member 57, a connecting member 58, a closing member 59, and a third insulating member 60.

〔Piezoelectric element〕
The piezoelectric element 41 is a member that exhibits a columnar shape as a whole. The piezoelectric element 41 includes a piezoelectric body that exhibits a piezoelectric action of a piezoelectric vertical effect. The piezoelectric element 41 is arranged inside the tip outer housing 31 (and the first inner housing 35).

Here, the piezoelectric longitudinal effect means that when an external force is applied to a stress application axis in the same direction as the charge generation axis of the piezoelectric body, a charge is generated on the surface of the piezoelectric body in the charge generation axis direction. Therefore, in this example, a signal (charge signal) due to the generated charge is output to the front end side surface and the rear end side surface of the piezoelectric element 41 according to the change in pressure along the center line direction. Become.

Next, a case where the piezoelectric lateral effect is used for the piezoelectric element 41 will be illustrated. The piezoelectric lateral effect means that when an external force is applied to a stress application axis located at a position orthogonal to the charge generation axis of the piezoelectric body, a charge is generated on the surface of the piezoelectric body in the direction of the charge generation axis. A plurality of piezoelectric bodies formed thinly in the shape of a thin plate may be laminated, and by laminating in this way, the electric charge generated in the piezoelectric body can be efficiently collected to increase the sensitivity of the sensor. Examples of the piezoelectric material that can be used in the piezoelectric element 41 include langasite crystals (langasite, langateite, langanite, LTGA) having a piezoelectric longitudinal effect and a piezoelectric lateral effect, quartz, gallium phosphate, and the like. can do. Further, as the piezoelectric body used in the piezoelectric element 41, it is preferable to use a single crystal (inorganic single crystal) composed of the above-mentioned inorganic material, and it is particularly desirable to use a Langasite-based single crystal.

[Tip electrode member]
The tip electrode member 42 is a member that exhibits a columnar shape as a whole. The tip electrode member 42 is made of a metal material such as stainless steel, which has both conductivity and high heat resistance. Examples of such a metal material include SUS630 known as precipitation hardening stainless steel and SUH660 known as austenitic heat-resistant steel (heat-resistant alloy). However, other metals or various alloys (various stainless steels, various heat-resistant steels, various heat-resistant alloys, etc.) can be adopted as long as they satisfy the required characteristics. In this example, the tip electrode member 42 is made of the same material as the diaphragm head 32 (for example, SUS630). The tip electrode member 42 is arranged inside the tip outer housing 31 and on the tip side of the piezoelectric element 41 so that the surface on the rear end side of the tip electrode member 42 comes into contact with the surface on the tip side of the piezoelectric element 41. It has become. In this example, the front end side surface, the rear end side surface, and the outer peripheral surface of the tip electrode member 42 are not particularly gold-plated, and the background of the metal material constituting the tip electrode material is exposed as it is. ing. Further, the outer diameter of the tip electrode member 42 is larger than the outer diameter of the piezoelectric element 41.

[Tip insulation member]
The tip insulating member 43 as an example of the pressure transmitting member or another member is a member having a columnar shape as a whole. The tip insulating member 43 is made of a ceramic material such as alumina, which has insulating properties and high heat resistance. The tip insulating member 43 is arranged inside the tip outer housing 31 and on the tip side of the tip electrode member 42, and the surface on the rear end side of the tip insulating member 43 comes into contact with the surface on the tip side of the tip electrode member 42. It is designed to do. On the other hand, the front end side surface of the tip end insulating member 43 comes into contact with the rear end side surface of the back surface central convex portion 32d provided on the diaphragm head 32. Further, the outer diameter of the tip insulating member 43 is smaller than the outer diameter of the tip electrode member 42, and is larger than the outer diameter of the back surface central convex portion 32d of the diaphragm head 32.

[Rear end electrode member]
The rear end electrode member 44 is a member that exhibits a columnar shape as a whole. The rear end electrode member 44 is made of a metal material such as stainless steel, which has both conductivity and high heat resistance. Examples of such a metal material include SUS630 known as precipitation hardening stainless steel and SUH660 known as austenitic heat-resistant steel (heat-resistant alloy). However, other metals or various alloys (various stainless steels, various heat-resistant steels, various heat-resistant alloys, etc.) can be adopted as long as they satisfy the required characteristics. In this example, the rear end electrode member 44 is made of the same material as the front end electrode member 42 (for example, SUS630). The rear end electrode member 44 is arranged inside the front end outer housing 31 and on the rear end side of the piezoelectric element 41, and the front end side surface of the rear end electrode member 44 is the rear end side surface of the piezoelectric element 41. It is designed to come into contact. In this example, the rear end side surface and the outer peripheral surface of the rear end electrode member 44 are gold-plated. On the other hand, the surface of the rear end electrode member 44 on the front end side, that is, the surface in contact with the rear end side of the piezoelectric element 41 is not particularly gold-plated, and is made of a metal material constituting the rear end electrode member 44. The skin is exposed as it is. Further, the outer diameter of the rear end electrode member 44 is larger than the outer diameter of the piezoelectric element 41.

[Rear end insulation member]
The rear end insulating member 45 is a member having a hollow structure and exhibiting an annular shape (cylindrical shape) as a whole. The rear end insulating member 45 is made of a ceramic material such as alumina, which has insulating properties and high heat resistance. The rear end insulating member 45 is arranged inside the front end outer housing 31 and on the rear end side of the rear end electrode member 44, and the surface of the rear end insulating member 45 on the front end side is the rear end of the rear end electrode member 44. It is designed to come into contact with the side surface. Further, the outer diameter of the rear end insulating member 45 is larger than the outer diameter of the piezoelectric element 41. In this example, the rear end insulating member 45 is made of the same material as the tip insulating member 43 (for example, alumina ceramics).

[1st coil spring]
The first coil spring 46 is a member that exhibits a spiral shape as a whole, and expands and contracts in the center line direction. The first coil spring 46 is made of a metal material such as phosphor bronze, which has both conductivity and high heat resistance, and its surface is gold-plated. The first coil spring 46 is arranged inside the tip outer housing 31. More specifically, the tip end side of the first coil spring 46 is arranged inside a through hole provided in the rear end insulating member 45, and the tip end thereof is a surface on the rear end side of the rear end electrode member 44. It is supposed to come into contact with. On the other hand, the rear end side of the first coil spring 46 protrudes to the rear end side of the rear end insulating member 45. Further, the outer diameter of the first coil spring 46 is smaller than the inner diameter of the through hole provided in the rear end insulating member 45.

[Conduction member]
The conductive member 47 is a member having a rod shape as a whole. The conductive member 47 is made of a conductive metal material such as brass, and its surface is gold-plated. The conduction member 47 includes a tip rod-shaped portion 471 located on the most tip side, an intermediate rod-shaped portion 472 located on the rear end side of the tip rod-shaped portion 471, and a rear end rod-shaped portion 473 located on the rear end side of the intermediate rod-shaped portion 472. And have. Further, in the conduction member 47, the outer diameter increases in the order of the tip rod-shaped portion 471, the intermediate rod-shaped portion 472, and the rear end rod-shaped portion 473. The conducting member 47 is arranged inside the tip outer housing 31. More specifically, the tip end side of the conduction member 47, that is, the tip end side of the tip rod-shaped portion 471 is inserted into the rear end side of the first coil spring 46 and is arranged inside the rear end insulating member 45. However, unlike the first coil spring 46, the tip of the tip rod-shaped portion 471 is not in contact with the surface on the rear end side of the rear end electrode member 44. At this time, the rear end of the first coil spring 46 abuts on the boundary portion (step portion) between the tip rod-shaped portion 471 and the intermediate rod-shaped portion 472 in the conduction member 47. In this example, the first coil spring 46 and the conduction member 47 are joined and integrated by laser welding. By the above procedure, the first coil spring 46 is sandwiched between the rear end electrode member 44 and the conduction member 47, so that the first coil spring 46 is compressed in the center line direction. On the other hand, the intermediate rod-shaped portion 472 and the rear end rod-shaped portion 473 of the conductive member 47 protrude toward the rear end side of the rear end insulating member 45. Further, the outer diameter of the tip rod-shaped portion 471 is smaller than the inner diameter of the first coil spring 46, and the outer diameter of the intermediate rod-shaped portion 472 is larger than the inner diameter of the first coil spring 46.

[Holding member]
The holding member 48 is a member having a hollow structure and having a tubular shape as a whole. The holding member 48 is made of a synthetic resin material such as PPS (Polyphenylene sulfide) or PPT (Polypropylene Terephthalate) having insulating properties. The holding member 48 has a tip portion located on the most tip side, an intermediate portion located on the rear end side of the tip portion, and a rear end portion located on the rear end side of the middle portion. The outer diameter of the holding member 48 increases in the order of the front end portion, the middle portion, and the rear end portion. The holding member 48 is arranged so as to straddle the inside of the tip outer housing 31 and the inside of the intermediate outer housing 33. The conduction member 47 is housed and held inside the holding member 48. More specifically, the holding member 48 houses the rear end side of the conduction member 47, that is, the rear end side of the rear end rod-shaped portion 473. By the above procedure, among the conduction members 47, the tip rod-shaped portion 471 and the intermediate rod-shaped portion 472 and the tip end side of the rear end rod-shaped portion 473 protrude to the tip end side of the holding member 48. On the other hand, a recess is formed at the rear end of the holding member 48 from the rear end side to the front end side. Further, the inner diameter of the hole provided in the holding member 48 is slightly larger than the outer diameter of the rear end rod-shaped portion 473 of the conducting member 47, and the conducting member 47 and the holding member 48 are press-fitted (clearance fit). ) Is integrated.

[Pressurizing member]
The pressure member 49 as an example of the spring member is a member having a hollow structure (through hole) and having a tubular shape as a whole. The pressurizing member 49 is made of a metal material such as stainless steel, which has conductivity and high heat resistance. Examples of such a metal material include SUS630 known as precipitation hardening stainless steel and SUH660 known as austenitic heat-resistant steel (heat-resistant alloy). However, other metals or various alloys (various stainless steels, various heat-resistant steels, various heat-resistant alloys, etc.) can be adopted as long as they satisfy the required characteristics. In this example, the pressurizing member 49 is made of the same material as the diaphragm head 32 (for example, SUS630). The pressurizing member 49 is inside the tip outer housing 31, and is arranged so as to straddle the inside of the first inner housing 35 and the inside of the second inner housing 36.

As shown in FIG. 5, the pressurizing member 49 includes a first tubular portion 491 located on the most distal end side, a second tubular portion 492 located on the rear end side of the first tubular portion 491, and a second tubular portion 49. It has a third tubular portion 493 located on the rear end side of the two tubular portions 492 and a fourth tubular portion 494 located on the rear end side of the third tubular portion 493. In the pressurizing member 49, the outer diameter of the second tubular portion 492 is larger than that of the first tubular portion 491, and the first step portion 495 is formed at the boundary between the two. Further, the outer diameter of the third tubular portion 493 is larger than that of the second tubular portion 492, and a second step portion 496 is formed at the boundary between the two. Further, the outer diameter of the fourth tubular portion 494 is smaller than that of the third tubular portion 493, and a third step portion 497 is formed at the boundary between the two. In this example, the outer diameters of the second tubular portion 492 and the fourth tubular portion 494 are set to be substantially the same. Further, the through hole provided inside the pressurizing member 49 has an inner diameter that gradually increases from the front end side to the rear end side, and is located inside the first tubular portion 491. Is provided with a fourth step portion 498.

From another point of view, the pressurizing member 49 is provided with a tubular portion 49a having a first inner diameter and relatively arranged on the rear end side, and a tubular portion 49a extending to the tip end side of the tubular portion 49a. It can also be grasped as having an extending portion 49b having a second inner diameter smaller (narrower) than the first inner diameter. That is, among the pressurizing members 49, the portion closer to the rear end side than the fourth step portion 498 is the tubular portion 49a, and the portion closer to the tip end side than the fourth step portion 498 is the extension portion 49b.

A piezoelectric element 41, a front electrode member 42, a rear end electrode member 44, a rear end insulating member 45, a first coil spring 46, and the like are housed inside a through hole provided in the pressurizing member 49. Then, the surface on the rear end side of the fourth step portion 498 provided on the pressurizing member 49 comes into contact with the surface on the tip end side of the tip electrode member 42. Further, the tip insulating member 43 is arranged in the opening on the tip side of the through hole provided in the pressurizing member 49.

The outer diameter of the first tubular portion 491 of the pressurizing member 49 is smaller than the inner diameter on the tip side from the first inner step portion 354 of the first inner housing 35. Further, the outer diameters of the second tubular portion 492, the third tubular portion 493, and the fourth tubular portion 494 are smaller than the inner diameter on the rear end side from the first inner step portion 354 of the first inner housing 35. It has become. Further, the outer diameter of the fourth tubular portion 494 is smaller than the inner diameter of the second inner housing 36.

On the other hand, among the through holes provided in the pressurizing member 49, the inner diameter of the tubular portion 49a on the rear end side is the outside of the piezoelectric element 41, the tip electrode member 42, the rear end electrode member 44, and the rear end insulating member 45. It is larger than the diameter. Further, among the through holes provided in the pressure member 49, the inner diameter of the extending portion 49b on the tip side is larger than the outer diameter of the tip insulating member 43.

Here, the pressurizing member 49 of the present embodiment functions as a spring by expanding and contracting the thinnest first tubular portion 491 in response to an external force. Then, as will be described later, the pressurizing member 49 applies a preload to the piezoelectric element 41 together with the support member 53 and the like.

[Insulated tube]
The insulating tube 50 is a member having a hollow structure by providing two openings along the center line direction and exhibiting a tubular shape as a whole. Further, the insulating tube 50 of the present embodiment is made of a material having an insulating property. Then, in the insulating tube 50 of the present embodiment, the tip electrode member 42, the piezoelectric element 41, the rear end electrode member 44, and the rear end insulating member 45 are housed inside and fixed while being in contact with each other in order from the tip side. By doing so, it has the function of integrating (modularizing) these together with itself. In the following description, the front electrode member 42, the piezoelectric element 41, the rear end electrode member 44, the rear end insulating member 45, and the insulating tube 50 may be collectively referred to as a “piezoelectric module 400”.

Here, the material constituting the insulating tube 50 may be selected from various materials regardless of whether it is organic or inorganic as long as it has insulating properties, but from the viewpoint of facilitating the production of the piezoelectric module 400, it is recommended. For example, it is desirable to use a heat-shrinkable organic material (for example, a synthetic resin material), that is, a heat-shrinkable tube. Further, among various synthetic resin materials, it is desirable to use a fluororesin material which is superior in heat resistance, insulating property and high frequency characteristics as compared with polyamide (for example, various nylons) and the like. Among the fluororesin materials, PTFE (polytetrafluoroethylene) and PFA (perfluoroalkoxy alkane), which have excellent thermal stability at a continuous use temperature of 260 ° C., can be used. When the operating environment temperature of the piezoelectric module 400 is 200 ° C. or lower, FEP (tetrafluoroethylene / hexafluoropropylene copolymer), which has a lower continuous operating temperature than PTFE or PFA but is easy to heat melt mold, is used. It is desirable to use it.

The insulating tube 50 is located inside the tip outer housing 31 and inside the pressurizing member 49. The surface on the tip end side of the insulating tube 50 faces the surface on the rear end side of the fourth step portion 498 provided on the pressurizing member 49 via a gap. Inside the insulating tube 50, the rear end side of the front end electrode member 42, the piezoelectric element 41 and the rear end electrode member 44, and the front end side of the rear end insulating member 45 are housed. In other words, the tip end side of the tip electrode member 42 protrudes toward the tip end side from the tip end of the insulating tube 50, and the rear end side of the rear end insulating member 45 is closer to the rear end side than the rear end side of the insulating tube 50. It is protruding. The outer diameter of the insulating tube 50 is smaller than the inner diameter of the through hole provided in the pressurizing member 49, and is larger than the inner diameter of the opening provided on the tip end side of the through hole. The inner diameter of the insulating tube 50 is substantially equal to the outer diameters of the piezoelectric element 41, the front electrode member 42, the rear end electrode member 44, and the rear end insulating member 45, respectively. The details of the piezoelectric module 400 including the insulating tube 50 will be described later.

[First insulating member]
The first insulating member 51 is a member that exhibits an annular shape as a whole. The first insulating member 51 is made of a ceramic material such as alumina, which has insulating properties and high heat resistance. The first insulating member 51 is arranged inside the tip outer housing 31, inside the first inner housing 35, and outside the pressurizing member 49. Then, the front end side surface of the first insulating member 51 comes into contact with the rear end side surface of the first inner step portion 354 of the first inner housing 35, and the rear end side surface of the first insulating member 51 becomes. The pressure member 49 comes into contact with the surface on the tip end side of the second step portion 496. The outer diameter of the first insulating member 51 is smaller than the inner diameter on the rear end side of the first inner step portion 354 of the first inner housing 35. Further, the inner diameter of the first insulating member 51 is larger than the outer diameter of the second tubular portion 492 of the pressurizing member 49. In this example, the first insulating member 51 is made of the same material as the rear end insulating member 45 (for example, alumina ceramics).

[Second insulating member]
The second insulating member 52 is a member that exhibits an annular shape as a whole. Like the first insulating member 51, the second insulating member 52 is made of a ceramic material such as alumina, which has insulating properties and high heat resistance. The second insulating member 52 is arranged inside the tip outer housing 31, inside the first inner housing 35, and outside the pressurizing member 49. Further, the second insulating member 52 is arranged on the rear end side of the first insulating member 51. Then, the front end side surface of the second insulating member 52 comes into contact with the rear end side surface of the third step portion 497 of the pressurizing member 49, and the rear end side surface of the second insulating member 52 is the second inside. It comes into contact with the surface of the housing 36 on the tip side of the second tip tubular portion 361. The outer diameter of the second insulating member 52 is smaller than the inner diameter on the rear end side of the first inner step portion 354 of the first inner housing 35. Further, the inner diameter of the second insulating member 52 is larger than the outer diameter of the fourth tubular portion 494 of the pressurizing member 49. In the present embodiment, the second insulating member 52 has the same dimensions as the first insulating member 51. Further, in this example, the second insulating member 52 is made of the same material as the first insulating member 51 (for example, alumina ceramics).

[Support member]
The support member 53 as an example of the abutting member is a member having a hollow structure and having a tubular shape as a whole. The support member 53 is made of a metal material such as stainless steel, which has high conductivity and high heat resistance. Examples of such a metal material include SUS630 known as precipitation hardening stainless steel and SUH660 known as austenitic heat-resistant steel (heat-resistant alloy). However, other metals or various alloys (various stainless steels, various heat-resistant steels, various heat-resistant alloys, etc.) can be adopted as long as they satisfy the required characteristics. In this example, the support member 53 is made of the same material as the pressurizing member 49 (for example, SUS630). The support member 53 is inside the tip outer housing 31, and the tip side thereof is arranged inside the pressurizing member 49. However, the rear end side of the support member 53 is in a state of protruding from the rear end of the pressurizing member 49. Then, the surface on the front end side of the support member 53 comes into contact with the surface on the rear end side of the rear end insulating member 45. Further, the boundary portion between the support member 53 and the pressure member 49 is subjected to laser welding over the entire circumference of the outer peripheral surface (for details, the third welded portion W3 (see FIG. 22) described later). This laser welding can be performed, for example, by spot welding in which a plurality of laser spots having a predetermined interval are formed over one circumference of the outer peripheral surface at the boundary between the support member 53 and the pressure member 49. In addition, instead of spot welding, seam welding over the outer peripheral surface may be performed. Inside the support member 53, the rear end side of the first coil spring 46 and the tip sides of the conduction member 47 and the holding member 48 are housed. The outer diameter of the support member 53 is slightly smaller than the inner diameter of the through hole provided in the pressurizing member 49. Further, the inner diameter of the through hole provided in the support member 53 is slightly larger than the outer diameter of the tip portion of the holding member 48.

[Second coil spring]
The second coil spring 54 is a member that exhibits a spiral shape as a whole, and expands and contracts in the center line direction. The second coil spring 54 is made of a metal material such as phosphor bronze, which has both conductivity and high heat resistance, and its surface is gold-plated. In this example, the second coil spring 54 is made of the same material as the first coil spring 46 (for example, phosphor bronze). The second coil spring 54 is arranged inside the tip outer housing 31. More specifically, the tip end side of the second coil spring 54 is arranged on the rear end side of the support member 53 and outside the outer peripheral surface, and the tip end of the fourth tubular portion 494 of the pressurizing member 49. It comes into contact with the surface on the rear end side. Inside the second coil spring 54, a conduction member 47, a holding member 48, a support member 53, and a tip end side of the first accommodating member 55 are arranged. The outer diameter of the second coil spring 54 is smaller than the inner diameter of the tip outer housing 31. Further, the inner diameter of the second coil spring 54 is larger than the outer diameter of the support member 53.

[First accommodating member]
FIG. 6A shows a perspective view of the first accommodating member 55 provided in the pressure detecting device 20. In FIG. 6A, the lower left side in the figure is the front end side, and the upper right side in the figure is the rear end side. Here, the first accommodating member 55 will be described with reference to FIG. 6A in addition to FIGS. 2 to 5.

The first accommodating member 55 is a member having a hollow structure and exhibiting a tubular shape as a whole. The first accommodating member 55 is made of a conductive metal material such as brass or stainless steel, and its surface is gold-plated.

The first accommodating member 55 is located on the rear end side of the first tip portion 551 located on the most tip side, the first intermediate portion 552 located on the rear end side of the first tip portion 551, and the first intermediate portion 552. It has a first rear end portion 553 and the like. In the first accommodating member 55, the outer diameter of the first intermediate portion 552 is larger than that of the first tip portion 551, and the first tip step portion 554 is formed at the boundary portion between the two. Further, the outer diameter of the first rear end portion 553 is larger than that of the first intermediate portion 552, and the first rear end step portion 555 is formed at the boundary portion between the two. The first accommodating member 55 is arranged inside the tip outer housing 31. More specifically, the tip end side of the first accommodating member 55, that is, the tip end side of the first tip end portion 551 faces the rear end side of the support member 53, and is on the outside of the outer peripheral surface of the first tip end portion 551. The second coil spring 54 is facing each other. The rear end of the second coil spring 54 abuts on the surface of the first accommodating member 55 on the tip end side of the first tip step portion 554. By the above procedure, the second coil spring 54 is sandwiched between the pressurizing member 49 and the first accommodating member 55, so that the second coil spring 54 is compressed in the center line direction. The tip portions of the conduction member 47 and the holding member 48 are accommodated inside the through hole provided in the first accommodating member 55. The outer diameters of the first tip portion 551, the first intermediate portion 552, and the first rear end portion 553 of the first accommodating member 55 are smaller than the inner diameter of the tip outer housing 31. Further, the outer diameter of the first tip portion 551 is smaller than the inner diameter of the second coil spring 54, and the outer diameter of the first intermediate portion 552 is larger than the inner diameter of the second coil spring 54. Further, the inner diameter of the first accommodating member 55 is larger than the outer diameter of the holding member 48.

[Second accommodating member]
FIG. 6B shows a perspective view of the second accommodating member 56 provided in the pressure detecting device 20. In FIG. 6B, the lower left side in the figure is the front end side, and the upper right side in the figure is the rear end side. Here, the second accommodating member 56 will be described with reference to FIG. 6B in addition to FIGS. 2 to 5.

The second accommodating member 56 is a member having a hollow structure and exhibiting a tubular shape as a whole. Like the first accommodating member 55, the second accommodating member 56 is made of a conductive metal material such as brass or stainless steel, and its surface is gold-plated.

The second accommodating member 56 is located on the rear end side of the second tip portion 561 located on the most tip side, the second intermediate portion 562 located on the rear end side of the second tip portion 561, and the second intermediate portion 562. It has a second rear end portion 563. In the second accommodating member 56, the outer diameter of the second intermediate portion 562 is larger than that of the second tip portion 561, and the second tip step portion 564 is formed at the boundary between the two. Further, the outer diameter of the second rear end portion 563 is larger than that of the second intermediate portion 562, and the second rear end step portion 565 is formed at the boundary portion between the two. Further, the second rear end portion 563 is formed with a circular hole 566 penetrating the outer peripheral surface and the inner peripheral surface thereof. The second accommodating member 56 is arranged so as to straddle the inside of the tip outer housing 31 and the inside of the intermediate outer housing 33. More specifically, the distal end side of the second accommodating member 56, that is, the distal end side of the second tip portion 561 is accommodated in the first rear end portion 553 of the first accommodating member 55, and the second tip step portion The front end side surface of 564 comes into contact with the rear end side surface of the first rear end portion 553. Further, an intermediate portion and a rear end portion of the holding member 48 are accommodated inside the through hole provided in the second accommodating member 56. The outer diameters of the second tip portion 561, the second intermediate portion 562, and the second rear end portion 563 of the second accommodating member 56 are smaller than the inner diameters of the tip outer housing 31 and the intermediate outer housing 33 facing each other. It has become. Further, the inner diameter of the second accommodating member 56 is larger than the outer diameter of the holding member 48. Further, the outer diameter of the second tip portion 561 of the second accommodating member 56 is slightly larger than the inner diameter of the first rear end portion 553 of the first accommodating member 55, and the first accommodating member 55 and the second accommodating member 55 and the second accommodating member 55. The member 56 is integrated by press fitting (tightening) and laser welding.

[Circuit built-in member]
As shown in FIG. 3, the circuit board built-in member 57 internally accommodates a circuit board 91 and a circuit board 91 that perform various processing using an electronic circuit on an electric signal due to a weak electric charge output by the piezoelectric element 41. This includes a sealing portion 92 that seals the circuit board 91. The circuit built-in member 57 is inside the intermediate outer housing 33, and almost the entire area except for a part on the rear end side is arranged inside the second accommodating member 56. In particular, the entire area of the circuit board 91 is arranged inside the second accommodating member 56. Further, the tip end side of the circuit built-in member 57 is fitted into a recess provided on the rear end side of the holding member 48. A metal plate provided on the tip end side of the circuit built-in member 57 (input signal plate 93 described later: see FIG. 7) comes into contact with the rear end side of the conduction member 47. Further, a metal plate provided on the outer peripheral surface of the circuit built-in member 57 (input grounding plate 94 described later: see FIG. 7) comes into contact with the inner peripheral surface of the second accommodating member 56. The details of the circuit built-in member 57 will be described later.

[Connecting member]
The connecting member 58 is a member having a columnar shape as a whole. The connecting member 58 includes a base material made of a synthetic resin material such as PPS or PPT having insulation, and wiring and terminals made of a metal material such as copper having conductivity. The connecting member 58 is arranged so as to straddle the inside of the intermediate outer housing 33 and the inside of the rear end outer housing 34. The portion (outer peripheral surface) of the connecting member 58 facing the intermediate outer housing 33 or the rear end outer housing 34 is made of a synthetic resin material so that the metal material is not exposed to this portion. There is. The rear end side of the circuit built-in member 57 faces the front end side of the connection member 58, and the metal plates provided on the circuit built-in member 57 (power receiving plate 95, output signal plate 96, and output grounding plate 97, which will be described later: FIG. 7) is fitted into the terminal provided on the connecting member 58. Further, on the rear end side of the connecting member 58, each conductor portion exposed on the tip side of the power supply line 81, the signal line 82, and the grounding line 83 (the details of which will be described later) constituting the connecting cable 80 is inserted. ing. The outer diameter of the connecting member 58 is slightly larger than the inner diameter of the rear end side of the intermediate outer housing 33, and the intermediate outer housing 33 and the connecting member 58 are integrated by press fitting. There is.

[Closing member]
The closing member 59 is a member having a columnar shape as a whole. However, the closing member 59 is formed with three through holes along the center line direction. The closing member 59 is made of an insulating rubber material. The front end side of the closing member 59 is arranged inside the rear end outer housing 34, and the rear end side protrudes outside the rear end of the rear end outer housing 34. The tip end side of the closing member 59 faces the rear end side of the connecting member 58. Further, the power supply line 81, the signal line 82, and the ground wire 83 described above are inserted into the three through holes provided in the closing member 59. The outer diameter of the closing member 59 is slightly larger than the inner diameter of the rear end outer housing 34 on the rear end side, and the rear end outer housing 34 and the closing member 59 are integrated by press fitting. It has become.

[Third insulating member]
The third insulating member 60 is a member having a hollow structure and having a tubular shape as a whole. However, the third insulating member 60 has a structure in which a cylindrical portion provided on the front end side and a portion of the annular portion provided on the rear end side are integrated. The third insulating member 60 is made of a synthetic resin material such as PPS having insulating properties. The third insulating member 60 is arranged so as to straddle the inside of the tip outer housing 31 and the inside of the intermediate outer housing 33. More specifically, the tip end side of the third insulating member 60 is arranged inside the tip outer housing 31, and the rear end side of the third insulating member 60 is arranged inside the intermediate outer housing 33. Has been done. The outer peripheral surface of the cylindrical portion of the third insulating member 60 faces the inner peripheral surface on the rear end side of the tip outer housing 31. Further, the surface on the tip end side of the annular portion of the third insulating member 60 comes into contact with the surface on the rear end side of the tip outer housing 31. On the other hand, the inner peripheral surface of the cylindrical portion of the third insulating member 60 is the outer peripheral surface of the first rear end portion 553 of the first accommodating member 55 and the outer peripheral surface of the second intermediate portion 562 of the second accommodating member 56. Is confronting with. Further, the surface of the third insulating member 60 on the rear end side of the annular portion comes into contact with the surface of the second accommodating member 56 on the tip end side of the second rear end step portion 565. The outer diameter of the cylindrical portion of the third insulating member 60 is smaller than the inner diameter of the rear end side of the tip outer housing 31. Further, the outer diameter of the annular portion of the third insulating member 60 is smaller than the inner diameter of the tip end side of the intermediate outer housing 33. On the other hand, the inner diameter of the cylindrical portion of the third insulating member 60 is larger than the outer diameter of the first rear end portion 553 of the first accommodating member 55 and the outer diameter of the second intermediate portion 562 of the second accommodating member 56. ing. Further, the inner diameter of the annular portion of the third insulating member 60 is larger than the outer diameter of the second intermediate portion 562 of the second accommodating member 56.

(Structure of seal part)
As shown in FIGS. 2 and 3, the seal portion 70 includes a first seal member 71 relatively located on the front end side and a second seal member 72 relatively located on the rear end side. ..

[First seal member]
The first seal member 71 is a member that exhibits an annular shape as a whole, and in this example, is composed of a square ring having a quadrangular cross section. The first sealing member 71 is made of a copper material having a tin-plated surface, which has high heat resistance and acid resistance. The first seal member 71 is attached to the outer peripheral surface of the tip outer housing 31 that constitutes the housing portion 30.

[Second seal member]
The second seal member 72 is a member that exhibits an annular shape as a whole, and in this example, is composed of an O-ring having a circular cross section. The second seal member 72 is made of a synthetic rubber material such as fluororubber, which has high mechanical resilience. The second seal member 72 is attached to the outer peripheral surface of the rear end outer housing 34 constituting the housing portion 30. The second seal member 72 has a role of a seal member for preventing water or the like from entering from the outside of the internal combustion engine 10, and also has a pressure detecting device 20 when the internal combustion engine 10 is operating or when the mounting environment is vibrated. Also serves as a vibration isolator to prevent the cylinder head 13 from vibrating and colliding with the inner surface of the communication hole 13a in the cylinder head 13. Therefore, as the second seal member 72, a fluororubber material having high resilience heat resistance and a long life of vibration suppression function is particularly suitable among materials having high mechanical resilience.

[Connection cable configuration]
As shown in FIGS. 2 and 3, the connection cable 80 covers the twisted power supply line 81, the signal line 82, and the ground wire 83, and the outer periphery of the power supply line 81, the signal line 82, and the ground wire 83. It is equipped with a member (not shown). Here, the power supply line 81, the signal line 82, and the ground wire 83 are each a conductor portion made of tin-plated annealed copper stranded wire, polyethylene (cross-linked polyethylene) or the like whose cross-linked structure is reinforced by using an electron wire or the like. It also has an insulating part that covers and insulates the outer periphery of the conductor part. Further, the covering member is made of a rubber material or a resin material having an insulating property. The connection cable 80 may be provided with a shield that shields the power supply line 81, the signal line 82, and the ground line 83, if necessary.

[Structure of circuit built-in members]
Next, the details of the circuit built-in member 57 described above will be described.
FIG. 7 is a perspective view of a circuit built-in member 57 provided in the pressure detection device 20. In FIG. 7, the lower left side in the figure is the front end side, and the upper right side in the figure is the rear end side.

As described above, the circuit built-in member 57 includes a circuit board 91 and a sealing portion 92. Further, the circuit built-in member 57 further includes an input signal plate 93, an input grounding plate 94, a power receiving plate 95, an output signal plate 96, and an output grounding plate 97.

(Circuit board)
FIG. 8 is a schematic configuration diagram of a circuit board 91 provided on the circuit built-in member 57. However, FIG. 8 also shows the connection relationship between the circuit board 91 and the input signal plate 93, the input grounding plate 94, the power receiving plate 95, the output signal plate 96, and the output grounding plate 97. Hereinafter, the circuit board 91 will be described with reference to FIGS. 7 and 8.

The circuit board 91 is a member having a rectangular plate shape as a whole. The circuit board 91 has a printed wiring board 911 on which a wiring pattern for mounting various electronic components (circuit elements) is formed, and a processing circuit 912 mounted on the printed wiring board 911.

In this embodiment, a so-called glass epoxy board based on a glass cloth base epoxy resin is used as the printed wiring board 911. The printed wiring board 911 is provided with an input signal terminal 91a, an input grounding terminal 91b, a power receiving terminal 91c, an output signal terminal 91d, and an output grounding terminal 91e as input / output terminals.

Here, a positive path (details will be described later) in the pressure detection device 20 is connected to the input signal terminal 91a via the input signal plate 93, and the input ground terminal 91b is connected to the input ground terminal 91b via the input ground plate 94. , The negative path (details will be described later) in the pressure detection device 20 is connected. On the other hand, the power supply line 81 is connected to the power receiving terminal 91c via the power receiving plate 95, the signal line 82 is connected to the output signal terminal 91d via the output signal plate 96, and the output ground terminal 91e is connected to the power line 82. , The ground wire 83 is connected via the output ground plate 97. In the printed wiring board 911, the input ground terminal 91b and the output ground terminal 91e are internally connected.

Further, the processing circuit 912 includes an integrating circuit 912a that integrates the charge signal input from the piezoelectric element 41 via the input signal terminal 91a and converts it into a voltage signal, and an output signal terminal that amplifies the converted voltage signal. It has an amplifier circuit 912b that outputs to 91d. Here, the integrator circuit 912a and the amplifier circuit 912b are provided with operational amplifiers (not shown), respectively, and a power supply voltage for operating them is supplied via the power receiving terminal 91c. Further, the ground of the integrator circuit 912a and the amplifier circuit 912b is connected to the input ground terminal 91b and the output ground terminal 91e. In this example, the processing circuit 912 is composed of a so-called integrated circuit (IC).

(Sealing part)
This time, the sealing portion 92 will be described with reference to FIG. 7.
The sealing portion 92 is a member having a columnar shape as a whole. The sealing portion 92 is made of a synthetic resin material such as epoxy having an insulating property. The sealing portion 92 includes a small diameter portion 921 located on the most advanced side, a medium diameter portion 922 located on the rear end side of the small diameter portion 921, and a large diameter portion 923 located on the rear end side of the medium diameter portion 922. I have. In the sealing portion 92, the outer diameter increases in the order of the small diameter portion 921, the medium diameter portion 922, and the large diameter portion 923. Further, the small diameter portion 921, the medium diameter portion 922, and the large diameter portion 923 each have a polygonal (for example, octagonal) cross-sectional shape. Here, in the present embodiment, the circuit board 91 is housed inside the medium diameter portion 922 of the sealing portion 92.

(Input signal board)
The input signal board 93 is a member having a plate shape (strip shape) as a whole. The input signal plate 93 is made of a conductive and elastic metal material such as brass, and its surface is gold-plated. The input signal plate 93 is arranged so as to project from the front end side surface of the small diameter portion 921 of the sealing portion 92 toward the tip end side. However, the rear end side of the input signal plate 93 is arranged inside the sealing portion 92 and is fixed by using the sealing portion 92. The tip end side of the input signal board 93 is bent so as to face upward in FIG. 7. The input signal plate 93 comes into contact with the rear end side of the conduction member 47.

(Input ground plate)
The input grounding plate 94 is a member having a plate shape (F shape) as a whole. The input ground plate 94 is also made of a conductive and elastic metal material such as brass, and its surface is gold-plated. The input ground plate 94 is configured by projecting outward from the outer peripheral surface of the medium diameter portion 922 of the sealing portion 92 and being bent along the outer peripheral surface. However, one end side of the input grounding plate 94 is arranged inside the sealing portion 92 and is fixed by using the sealing portion 92. The input grounding plate 94 comes into contact with the inner peripheral surface of the second accommodating member 56.

(Power receiving plate)
The power receiving plate 95 is a member having a plate shape (strip shape) as a whole. The power receiving plate 95 is also made of a conductive and elastic metal material such as brass, and its surface is gold-plated. The power receiving plate 95 is arranged so as to project from the surface of the sealing portion 92 on the rear end side of the large diameter portion 923 toward the rear end side. However, the tip end side of the power receiving plate 95 is arranged inside the sealing portion 92 and is fixed by using the sealing portion 92. The rear end side of the power receiving plate 95 is bent so as to face upward in FIG. 7. The power receiving plate 95 is connected to the power supply line 81 via the connecting member 58.

(Output signal board)
The output signal plate 96 is a member having a plate shape (strip shape) as a whole. The output signal plate 96 is also made of a conductive and elastic metal material such as brass, and its surface is gold-plated. The output signal plate 96 is arranged so as to project from the surface of the sealing portion 92 on the rear end side of the large diameter portion 923 toward the rear end side. However, the tip end side of the output signal plate 96 is arranged inside the sealing portion 92 and is fixed by using the sealing portion 92. Further, the output signal plate 96 is arranged adjacent to the power receiving plate 95. The rear end side of the output signal plate 96 is bent so as to face downward in FIG. 7. The output signal plate 96 is connected to the signal line 82 via the connecting member 58.

(Output grounding plate)
The output grounding plate 97 is a member having a plate shape (strip shape) as a whole. The output grounding plate 97 is also made of a conductive and elastic metal material such as brass, and its surface is gold-plated. The output ground plate 97 is arranged so as to project from the surface of the sealing portion 92 on the rear end side of the large diameter portion 923 toward the rear end side. However, the tip end side of the output ground plate 97 is arranged inside the sealing portion 92 and is fixed by using the sealing portion 92. Further, the output ground plate 97 is arranged adjacent to the output signal plate 96. The rear end side of the output ground plate 97 is bent so as to face upward in FIG. 7. The output grounding plate 97 is connected to the grounding wire 83 via the connecting member 58.

[Piezoelectric module configuration]
Next, the details of the above-mentioned piezoelectric module 400 will be described.
FIG. 9A shows a top view of the piezoelectric module 400 provided in the pressure detection device 20, and FIG. 9B is a sectional view taken along line IXB-IXB of FIG. 9A (longitudinal section of the piezoelectric module 400). View) is shown. Here, in FIG. 9B, the vertical direction in the figure is the center line direction, and the upper side in the figure is the tip side.

As described above, in the piezoelectric module 400 of the present embodiment, the front electrode member 42, the piezoelectric element 41, the rear end electrode member 44, and the rear end insulating member 45 are arranged in this order from the front end side. Then, as shown in FIG. 9B, the insulating tube 50 is arranged so as to cover the outer peripheral surfaces of the front end electrode member 42, the piezoelectric element 41, the rear end electrode member 44, and the rear end insulating member 45. .. Here, the insulating tube 50 covers the entire outer peripheral surface of the piezoelectric element 41 and the rear end electrode member 44 located in the middle in the center line direction. On the other hand, the insulating tube 50 covers the rear end side of the outer peripheral surface of the tip electrode member 42 located on the tip side in the center line direction, but does not cover the front end side of the outer peripheral surface. On the other hand, the insulating tube 50 covers the front end side of the outer peripheral surface of the rear end insulating member 45 located on the rear end side in the center line direction, but does not cover the rear end side of the outer peripheral surface.

Here, in the piezoelectric module 400 of the present embodiment, the direction intersecting (orthogonal) with the center line direction of the front end electrode member 42, the piezoelectric element 41, the rear end electrode member 44, and the rear end insulating member 45 (hereinafter, "diameter direction"). The centers of (referred to as ") are almost overlapped (almost coincident). This is due to the heat shrinkage of the insulating tube 50 constituting the piezoelectric module 400.

[Electrical connection structure in pressure detector]
Here, the electrical connection structure of the pressure detection device 20 will be described.
(Positive route)
In the pressure detection device 20, the end face (positive electrode) on the rear end side of the piezoelectric element 41 is electrically connected to the rear end electrode member 44, the first coil spring 46, and the conduction member 47. Further, the conduction member 47 is electrically connected to the input signal plate 93 provided in the circuit built-in member 57. Then, the input signal board 93 is electrically connected to the input signal terminal 91a of the circuit board 91 provided on the same circuit built-in member 57. In the following, electrical from the rear end side surface of the piezoelectric element 41 to the input signal terminal 91a of the circuit board 91 via the rear end electrode member 44, the first coil spring 46, the conduction member 47, and the input signal plate 93. The route is referred to as a "positive route".

(Negative route)
On the other hand, in the pressure detection device 20, the end face (negative electrode) on the tip end side of the piezoelectric element 41 is electrically connected to the tip electrode member 42, the pressurizing member 49, and the support member 53. Further, the pressurizing member 49 is electrically connected to the input ground plate 94 provided on the second coil spring 54, the first accommodating member 55, the second accommodating member 56, and the circuit built-in member 57. Then, the input grounding plate 94 is electrically connected to the input grounding terminal 91b of the circuit board 91 provided on the same circuit built-in member 57. In the following, from the front end side surface of the piezoelectric element 41, the tip electrode member 42, the pressurizing member 49, the support member 53, the second coil spring 54, the first accommodating member 55, the second accommodating member 56, and the input grounding plate 94 are interposed. The electrical path leading to the input ground terminal 91b of the circuit board 91 is referred to as a "negative path".

(Case route)
On the other hand, in the pressure detection device 20, the diaphragm head 32 is electrically connected to the front end outer housing 31, the intermediate outer housing 33, and the rear end outer housing 34. Further, the diaphragm head 32 is electrically connected to the first internal housing 35 and the second internal housing 36. In the following, the electrical paths from the second inner housing 36 to the first inner housing 35, the diaphragm head 32, the front outer housing 31, the intermediate outer housing 33, and the rear end outer housing 34 are referred to as "housing. It is called "body pathway". When the pressure detection device 20 is attached to the cylinder head 13 of the internal combustion engine 10 shown in FIG. 1, for example, the tip outer housing 31 comes into contact with the inner peripheral surface of the communication hole 13a. At this time, the cylinder head 13 (and the cylinder block 11) and the housing path have substantially the same potential.

(Relationship between positive and negative paths)
Here, in the pressure detection device 20 of the present embodiment, a negative path exists outside the positive path. In other words, the positive path is contained inside the negative path. The positive path and the negative path are electrically insulated by the rear end insulating member 45, the holding member 48, the insulating tube 50, and the air gap formed between the two paths.

(Relationship between negative route and housing route)
Further, in the pressure detection device 20, the housing path exists outside the negative path. In other words, a negative path is housed inside the housing path. The negative path and the housing path are electrically connected by the tip insulating member 43, the first insulating member 51, the second insulating member 52, the third insulating member 60, and the air gap formed between both paths. It is insulated.

(Relationship between chassis path and positive path)
Further, in the pressure detection device 20, as a result, the housing path exists outside the positive path. In other words, the positive path is housed inside the housing path. Then, as described above, the positive path and the negative path are electrically insulated, and the negative path and the housing path are electrically insulated, so that the housing path and the positive path are obtained. However, it is electrically insulated.

[Pressure detection operation by pressure detection device]
Then, the pressure detection operation by the pressure detection device 20 will be described.
When the internal combustion engine 10 is operating, the pressure (combustion pressure) generated in the combustion chamber C is applied to the pressure receiving surface 32a of the diaphragm head 32. In the diaphragm head 32, the pressure received by the pressure receiving surface 32a is transmitted to the back surface central convex portion 32d on the back side, and further transmitted from the back surface center convex portion 32d to the tip electrode member 42 via the tip insulating member 43. Then, the pressure transmitted to the front end electrode member 42 acts on the piezoelectric element 41 sandwiched between the front end electrode member 42 and the rear end electrode member 44, and the piezoelectric element 41 generates an electric charge according to the received pressure. The electric charge generated in the piezoelectric element 41 is supplied as an electric charge signal to the input signal terminal 91a and the input ground terminal 91b of the circuit board 91 via the positive path and the negative path. The charge signal supplied to the circuit board 91 is converted into an output signal by performing various processes in the processing circuit 912 mounted on the circuit board 91. Then, the output signal output from the output signal terminal 91d of the circuit board 91 is transmitted to the control device 100 via the connecting member 58 and the connecting cable 80.

[Manufacturing procedure of pressure detector]
FIG. 10 is a diagram for explaining a manufacturing procedure of the pressure detecting device 20 (actually, a connecting body in which the pressure detecting device 20 and the connecting cable 80 are integrated) of the present embodiment. In the following, the manufacturing procedure of the connected body will be described with reference to FIGS. 2 to 9 described above in addition to FIG.

(Assembly of the first structure)
First, the back surface of the diaphragm head 32, that is, the rear end side, and the front end side of the first internal housing 35 are opposed to each other. Subsequently, the front end side surface of the first outer step portion 353 of the first inner housing 35 is abutted against the rear end side surface of the back surface annular convex portion 32f of the diaphragm head 32. Along with this, the first tip tubular portion 351 of the first inner housing 35 is arranged in the back surface annular recess 32c of the diaphragm head 32. Then, in this state, the first structure is obtained by performing laser welding (forming the first welded portion W1) around the boundary portion between the diaphragm head 32 and the first internal housing 35.

(Assembly of the second structure)
Next, the first insulating member 51 is inserted into the first internal housing 35 of the first structure from the rear end side. At this time, the surface on the tip end side of the first insulating member 51 abuts on the surface on the rear end side of the first inner step portion 354 in the first inner housing 35. As a result, the outer peripheral surface of the first insulating member 51 faces the inner peripheral surface on the rear end side of the first inner housing 35.

Subsequently, the pressurizing member 49 is inserted into the first internal housing 35 from the rear end side with the first tubular portion 491 as the front end side. At this time, the surface on the front end side of the second step portion 496 of the pressurizing member 49 abuts on the surface on the rear end side of the first insulating member 51. At this time, there is an air gap between the outer peripheral surface of the pressure member 49 on the tip end side (first tubular portion 491 side) and the inner peripheral surfaces of the diaphragm head 32 and the first inner housing 35. It is formed. Further, at this time, an air gap is also formed between the surface of the pressurizing member 49 on the tip end side of the first step portion 495 and the surface of the first inner housing 35 on the rear end side of the first inner step portion 354. It is formed. Further, at this time, an air gap is also formed between the outer peripheral surface of the third tubular portion 493 of the pressurizing member 49 and the inner peripheral surface of the first inner housing 35. Furthermore, at this time, the rear end side of the fourth tubular portion 494 of the pressurizing member 49 protrudes to the outside (rear end side) from the rear end of the first inner housing 35.

Then, the second insulating member 52 is inserted between the first inner housing 35 and the pressurizing member 49 from the rear end side. At this time, the surface on the tip end side of the second insulating member 52 abuts on the surface on the rear end side of the third step portion 497 of the pressurizing member 49. As a result, the inner peripheral surface of the second insulating member 52 faces the outer peripheral surface of the fourth tubular portion 494 of the pressure member 49. Further, the outer peripheral surface of the second insulating member 52 faces the inner peripheral surface on the rear end side of the first inner housing 35.

Next, the second inner housing 36 is inserted into the first inner housing 35 from the rear end side with the second tip tubular portion 361 as the tip side. At this time, the front end side surface of the second tip tubular portion 361 of the second inner housing 36 abuts on the rear end side surface of the second insulating member 52. As a result, the inner peripheral surface of the second inner housing 36 faces the outer peripheral surface of the fourth tubular portion 494 of the pressurizing member 49 via the air gap. Further, the outer peripheral surface on the front end side of the second inner housing 36 faces the inner peripheral surface on the rear end side of the first inner housing 35. Further, the second rear end tubular portion 362 of the second inner housing 36 protrudes to the outside (rear end side) of the rear end of the first inner housing 35. As a result, the surface on the tip end side of the second outer step portion 363 in the second inner housing 36 passes through the air gap with the surface on the rear end side of the first rear end tubular portion 352 in the first inner housing 35. Face each other. Then, in this state, both the pressurizing member 49 and the diaphragm head 32 constituting the first structure are subjected to a "setting process". Then, in this state, the second structure is obtained by performing laser welding (forming the second welded portion W2) around the boundary portion between the first inner housing 35 and the second inner housing 36. Be done. The specific manufacturing procedure of the second structure will be described later.

(Assembly of the third structure)
Further, in a process different from the assembly of the first structure and the second structure described above, the insulating tube 50 is attached to the front end electrode member 42, the piezoelectric element 41, the rear end electrode member 44, and the rear end insulation from the rear end side. The third structure (piezoelectric module 400) is obtained by inserting the members 45 in this order and then heat-shrinking the insulating tube 50 (see FIG. 9).

(Assembly of the 4th structure)
Next, the tip insulating member 43 is inserted into the pressure member 49 of the second structure described above from the rear end side. At this time, the front end side surface of the tip end insulating member 43 abuts on the rear end side surface of the back surface central convex portion 32d of the diaphragm head 32.

Subsequently, the third structure (piezoelectric module 400) is inserted into the pressurizing member 49 from the rear end side with the tip electrode member 42 as the tip side. At this time, the surface on the front end side of the tip electrode member 42 abuts on the surface on the rear end side of the tip insulating member 43. At this time, the outer peripheral surface of the insulating tube 50 faces the inner peripheral surface on the tip end side of the pressurizing member 49.

Next, the support member 53 is inserted into the pressurizing member 49 from the rear end side. At this time, the surface on the front end side of the support member 53 abuts on the surface on the rear end side of the rear end insulating member 45. As a result, the outer peripheral surface of the support member 53 on the tip end side faces the inner peripheral surface of the pressurizing member 49. Further, the rear end side of the support member 53 protrudes to the outside (rear end side) from the rear end of the pressurizing member 49.

Then, the pressurizing member 49 is subjected to a "preload applying process" that adjusts the load applied to the piezoelectric element 41 via each member by moving (advancing / retreating) the support member 53 along the center line direction. .. Then, with the load adjusted, laser welding is performed around the boundary between the pressure member 49 and the support member 53 (the third weld W3 is formed) to obtain the fourth structure. Be done. However, in this explanation, the tip insulating member 43 is introduced for the first time when assembling the fourth structure, but when assembling the second structure as described later, the inside of the second structure is introduced. The tip insulating member 43 may be installed in advance.

The magnitude of the preload applied to the piezoelectric element 41 in the assembly of the fourth structure is the yield applied to set both the diaphragm head 32 and the pressurizing member 49 in the assembly of the second structure. It is smaller than the magnitude of the load (setting stress), for example, about half.

(Assembly of the 5th structure)
Further, in a process different from the assembly of the first structure to the fourth structure described above, the third insulating member 60 is inserted into the front end outer housing 31 from the rear end side. At this time, the surface on the tip end side of the portion of the annular portion provided on the rear end side of the third insulating member 60 abuts on the surface on the rear end side of the tip outer housing 31. As a result, the outer peripheral surface of the cylindrical portion provided on the tip end side of the third insulating member 60 faces the inner peripheral surface of the tip outer housing 31. By the above procedure, a fifth structure having the tip outer housing 31 and the third insulating member 60 is obtained.

(Assembly of the 6th structure)
Further, in a process different from the assembly of the fifth structure described above, the first accommodating member 55 having the first tip portion 551 as the tip side is attached to the first accommodating member 55 from the rear end side, and the second tip portion 561 is the tip side. The accommodating member 56 is inserted. At this time, the second tip portion 561 located on the tip end side of the second accommodating member 56 fits inside the first rear end portion 553 provided on the rear end side of the first accommodating member 55. Then, in this state, laser welding is performed around the boundary between the first accommodating member 55 and the second accommodating member 56.

Then, the welded material of the first accommodating member 55 and the second accommodating member 56 is inserted into the second coil spring 54 from the rear end side with the first accommodating member 55 as the tip end side. At this time, the first tip portion 551 of the first accommodating member 55 is housed inside the rear end side of the second coil spring 54, and the rear end of the second coil spring 54 is placed on the tip end side surface of the first tip step portion 554. Hits. Then, in this state, the sixth structure is obtained by performing laser welding on the boundary portion between the second coil spring 54 and the first accommodating member 55 over one circumference.

(Assembly of the 7th structure)
Next, the sixth structure is inserted (press-fitted) into the tip outer housing 31 of the fifth structure described above from the rear end side with the second coil spring 54 as the tip side. At this time, the front end side surface of the second rear end step portion 565 of the second accommodating member 56 abuts on the rear end side surface of the annular portion of the third insulating member 60. At this time, the outer peripheral surface of the second intermediate portion 562 of the second accommodating member 56 faces the inner peripheral surface of the cylindrical portion of the third insulating member 60. By the above procedure, a seventh structure having a fifth structure and a sixth structure is obtained.

(Assembly of the 8th structure)
Next, the seventh structure is inserted into the above-mentioned fourth structure from the rear end side with the tip outer housing 31 as the tip side. At this time, the front end side surface of the front end outer housing 31 abuts on the rear end side surface of the back surface annular flat portion 32e of the diaphragm head 32. At this time, each component other than the diaphragm head 32 in the fourth structure is housed inside the tip outer housing 31. At this time, the tip end side of the second coil spring 54 provided in the seventh structure abuts against the rear end side surface of the pressurizing member 49 provided in the fourth structure. Along with this, the second coil spring 54 is compressed in the center line direction. Further, at this time, the outer peripheral surfaces of the first inner housing 35 and the second inner housing 36 in the fourth structure face the inner peripheral surface of the tip outer housing 31 via an air gap. Furthermore, at this time, the diaphragm head 32 is exposed to the outside together with the tip outer housing 31 with the pressure receiving surface 32a and the surface center recess 32b facing outward. Then, in this state, the eighth structure is obtained by performing laser welding on the boundary portion between the tip outer housing 31 and the diaphragm head 32 over one circumference.

(Assembly of the 9th structure)
Further, in a process different from the assembly of the first structure to the eighth structure described above, the conduction member 47 is inserted (press-fitted) into the holding member 48 from the rear end side with the tip rod-shaped portion 471 as the tip side. .. At this time, the tip rod-shaped portion 471 and the intermediate rod-shaped portion 472 of the conduction member 47 and the tip end side of the rear end rod-shaped portion 473 are made to protrude toward the tip end side of the holding member 48. As a result, the rear end side of the rear end rod-shaped portion 473 of the conduction member 47 faces the inner peripheral surface of the holding member 48.

Then, the integrated body of the conduction member 47 and the holding member is inserted into the first coil spring 46 from the rear end side with the tip rod-shaped portion 471 of the conduction member 47 as the tip side. At this time, the tip rod-shaped portion 471 of the conduction member 47 is housed inside the rear end side of the first coil spring 46, and the first coil spring is placed on a surface serving as a boundary between the tip rod-shaped portion 471 and the intermediate rod-shaped portion 472 of the conduction member 47. The rear end of 46 hits. Then, in this state, the ninth structure is obtained by performing laser welding on the boundary portion between the first coil spring 46 and the conductive member 47 over one circumference.

(Assembly of the 10th structure)
Further, in a process different from the assembly of the ninth structure described above, the circuit board 91, the input signal plate 93, the input grounding plate 94, the power receiving plate 95, the output signal plate 96, and the output grounding plate 97 (in FIG. 10). , "Various plates 93 to 97") are sealed using the sealing portion 92 (transfer mold in this case) to obtain a tenth structure (circuit built-in member 57).

(Assembly of the 11th structure)
Next, the eleventh structure is formed by fitting the tenth structure (circuit built-in member 57) into the recess provided on the rear end side of the holding member 48 of the ninth structure from the rear end side. can get. At this time, the input signal plate 93 provided on the front end side of the circuit built-in member 57 is in contact with and connected to the rear end of the rear end rod-shaped portion 473 of the conduction member 47.

(Assembly of the 12th structure)
Next, the eleventh structure is inserted into the support member 53 of the eighth structure described above from the rear end side with the first coil spring 46 as the tip side. At this time, the tip of the first coil spring 46 abuts on the rear end side surface of the rear end electrode member 44 via the through hole provided in the rear end insulating member 45. Along with this, the first coil spring 46 is compressed in the center line direction. Further, at this time, the front end side of the conduction member 47 and the holding member 48 is housed inside the support member 53, and the rear end side thereof is housed inside the first housing member 55 and the second housing member 56. .. Further, at this time, the tenth structure (circuit built-in member 57) is housed inside the second accommodating member 56, and the input grounding plate 94 provided on the outer peripheral surface of the tenth structure (circuit built-in member 57) is , Facing and contacting the inner peripheral surface of the second accommodating member 56. Here, in the present embodiment, with the eleventh structure inserted into the eighth structure, the tenth structure (circuit built-in member 57) is provided in the round hole 566 provided in the second accommodating member 56. The input grounding plate 94 is made to face each other. In other words, when viewed from the outside, the input ground plate 94 provided in the tenth structure (circuit built-in member 57) can be seen in the round hole 566 provided in the second accommodating member 56. Then, in this state, at the forming site of the round hole 566, the second rear end portion 563 of the second accommodating member 56 (more specifically, the inner peripheral surface of the round hole 566) is formed through the round hole 566. , The twelfth structure can be obtained by soldering the input ground plate 94.

(Assembly of the 13th structure)
Next, the connecting member 58 is inserted into the twelfth structure from the rear end side. At this time, the power receiving plate 95, the output signal plate 96, and the output grounding plate 97 provided on the rear end side of the tenth structure (circuit built-in member 57) are in contact with and connected to the connecting member 58.

Subsequently, the connection cable 80 is connected to the twelfth structure to which the connection member 58 is attached from the rear end side. At this time, each of the power supply line 81, the signal line 82, and the ground wire 83 constituting the connection cable 80 is inserted into the rear end side of the connection member 58. As a result, the power receiving plate 95 is connected to the power supply line 81 via the connecting member 58, the output signal plate 96 is connected to the signal line 82 via the connecting member 58, and the output grounding plate 97 connects the connecting member 58. It is connected to the ground wire 83 via. By the above procedure, a thirteenth structure having a twelfth structure, a connecting member 58, and a connecting cable 80 is obtained.

(Assembly of the 14th structure)
Further, in a process different from the assembly of the first structure to the thirteenth structure described above, the rear end outer housing 34 is inserted into the intermediate outer housing 33 from the rear end side. At this time, the rear end side of the intermediate outer housing 33 and the front end side of the rear end outer housing 34 are fitted to each other. Then, in this state, the 14th structure is obtained by performing laser welding on the boundary portion between the intermediate outer housing 33 and the rear end outer housing 34 over one circumference.

(Assembly of the 15th structure)
Next, the 14th structure is inserted into the 13th structure described above from the rear end side. At this time, the rear end side of the tip outer housing 31 and the tip side of the intermediate outer housing 33 are fitted to each other. At this time, the power supply line 81, the signal line 82, and the ground line 83 are made to penetrate inside the 14th structure.

Subsequently, the closing member 59 is inserted into the connecting body of the 13th structure and the 14th structure from the rear end side. At this time, the power supply line 81, the signal line 82, and the ground wire 83 are made to penetrate through the three through holes provided in the closing member 59, respectively. At this time, the tip end side (almost the entire area) of the closing member 59 is pushed into the rear end portion of the rear end outer housing 34 and fixed. Then, in this state, the fifteenth structure is obtained by performing laser welding on the boundary portion between the tip outer housing 31 and the intermediate outer housing 33 over one circumference.

(Assembly of 16th structure)
Next, the second seal member 72 is inserted into the fifteenth structure from the tip end side. At this time, the second seal member 72 is positioned by abutting against a step portion provided on the outer peripheral surface of the rear end outer housing 34.
Subsequently, the first seal member 71 is inserted into the fifteenth structure to which the second seal member 72 is attached from the tip end side. At this time, the first seal member 71 is positioned by abutting against a step portion provided on the outer peripheral surface of the tip outer housing 31. By the above procedure, a 16th structure (connecting body of the pressure detecting device 20 and the connecting cable 80) having the 15th structure and the sealing portion 70 (the first sealing member 71 and the second sealing member 72) is obtained.

[Second structure]
Next, the manufacturing procedure of the second structure in the manufacturing procedure of the pressure detecting device 20 described above will be described in more detail.

(Setting device)
FIG. 11 is a diagram for explaining a schematic configuration of a setting device 600 used for manufacturing the second structure. In the present embodiment, the setting device 600 shown in FIG. 11 sets both the diaphragm head 32 and the pressurizing member 49 constituting the second structure. Then, welding of the first internal housing 35 and the second internal housing 36 in the second structure is performed using a device different from the setting device 600 (laser welding device (not shown)).

The setting device 600 shown in FIG. 11 includes a pedestal 610 on which an object to be set (for example, a second structure) can be loaded, and a piston 620 arranged above the pedestal 610 and movably provided in the vertical direction. ing. Further, the setting device 600 is provided through a through hole provided in a portion of the pedestal 610 facing the lower end portion of the piston 620, and is provided with a displacement detection needle 630 that is movably provided in the vertical direction. I have. A spring (not shown) is attached to the displacement detection needle 630 so that the upper end of the displacement detection needle 630 stands still in a state of protruding upward from the loading surface of the pedestal 610 in the initial state. Is being positioned. The displacement detection needle 630 may be positioned by air pressure instead of the spring. The setting device 600 includes an operation control unit 640 that controls the operation of the piston 620 based on the detection result of the displacement detection needle 630.

Here, the pedestal 610 and the piston 620 used in the setting device 600 are made of a material (for example, tool steel) having a higher rigidity than the diaphragm head 32 and the pressurizing member 49.

FIG. 12 is a diagram for explaining the configuration of the piston 620 used in the setting device 600 shown in FIG. Here, FIG. 12A is a perspective view of the piston 620, and FIG. 12B is a cross-sectional view taken along the line XIIB-XIIB of FIG. 12A. In FIG. 12A, the lower left side in the figure corresponds to the lower side in FIG. 11, and the upper right side in the figure corresponds to the upper side in FIG. Further, in FIG. 12A, the lower left side in the figure corresponds to the front end side in the second structure, and the upper right side in the figure corresponds to the rear end side in the second structure.

The piston 620 as an example of the pressing member has a piston main body 621 having a substantially columnar shape, and a perforation 622 provided so as to penetrate the inside of the piston main body 621 along the longitudinal direction. Further, the piston 620 is provided on the tip end side of the piston body 621 so as to be substantially flat, and a tip surface 623 in which one end of the perforation 622 is formed in the center thereof and a side portion of the piston body 621. It has a side surface 624 and an inclined surface 625 provided at a boundary between the tip surface 623 and the side surface 624.

Here, the outer diameter of the portion of the piston 620 where the side surface 624 is provided is slightly smaller than the inner diameter of the tubular portion 49a (see FIG. 5) of the pressurizing member 49. Further, the outer diameter of the portion of the piston 620 where the tip surface 623 is provided is larger than the outer diameter of the tip insulating member 43 (see FIG. 4) and smaller than the inner diameter of the tubular portion 49a of the pressurizing member 49. It has become. Further, the inner diameter of the perforation 622 provided on the tip surface 623 is smaller than the outer diameter of the tip insulating member 43.

(Manufacturing procedure of the second structure)
FIG. 13 is a flowchart showing a manufacturing procedure of the second structure. In this example, the second structure including the first structure (diaphragm head 32 and the first internal housing 35), the pressurizing member 49, the first insulating member 51, the second insulating member 52, and the second internal housing 36 is included. When manufacturing the structure, the tip insulating member 43 that later constitutes the fourth structure is used as a manufacturing part.

FIG. 14 is a cross-sectional view showing the configuration of the first structure used in the “temporary assembly step” of step 10 described later. FIG. 15 is a cross-sectional view for explaining the “temporary assembly step” of step 10 described later. FIG. 16 is a diagram for explaining the “installation step” of step 20 described later. FIG. 17 is a diagram for explaining the “insertion step” of step 30 described later. FIG. 18 is a diagram for explaining the “pressurization step” of step 40, which will be described later. FIG. 19 is a diagram for explaining the “drawing step” of step 50, which will be described later. FIG. 20 is a cross-sectional view showing the configuration of the second structure obtained through the “removal step” of step 60 and the “welding step” of step 70, which will be described later. Hereinafter, the manufacturing procedure of the second structure will be described with reference to FIGS. 14 to 20 while referring to FIG. 13 as a basis.

[Temporary assembly process]
First, as shown in FIG. 14, the first structure, which is the basis of the second structure, has a diaphragm head 32 located relatively on the front end side (lower side in the drawing) and a relatively rear end side (relatively on the rear end side (lower side in the drawing). The first inner housing 35 located on the upper side in the drawing, and the first welded portion W1 formed by welding (laser welding) the diaphragm head 32 and the first inner housing 35 over the outer peripheral surface. Have.

Then, first, a temporary assembly step of temporarily assembling each component of the second structure including the first structure and the tip insulating member 43 constituting the fourth structure is executed (step 10, step 10, (See FIG. 15).

In step 10, first, the first structure is temporarily placed so that its rear end side (first internal housing 35 side) faces upward. Next, the first insulating member 51, the pressurizing member 49, the second insulating member 52, and the second internal housing 36 are inserted in this order from above the first structure, that is, from the rear end side. As a result, the second structure is temporarily assembled. Subsequently, the tip insulating member 43 is inserted into the temporarily assembled second structure from above the first structure, that is, from the rear end side. At this time, the tip insulating member 43 is fitted into the opening provided in the extending portion 49b of the pressurizing member 49, and the surface on the tip side of the tip insulating member 43 is the center of the back surface of the diaphragm head 32. It abuts on the rear end side surface of the convex portion 32d.

In the following, the temporary assembly of each component of the second structure and the tip insulating member 43 obtained in step 10 will be referred to as a temporary assembly.

[Installation process]
Next, an installation step of installing the temporary assembly obtained in step 10 on the pedestal 610 of the setting device 600 is executed (see step 20 and FIG. 16).

In step 20, the temporary assembly is loaded on the pedestal 610 of the setting device 600. Specifically, the temporary assembly is placed on the pedestal 610 so that the surface center recess 32b provided on the diaphragm head 32 of the temporary assembly contacts the displacement detection needle 630 protruding upward from the upper surface of the pedestal 610. Load. At this time, the rear end side of the temporary assembly faces vertically upward. Then, the temporary assembly temporarily installed on the pedestal 610 is fixed on the pedestal 610 by a jig (not shown).

Here, after assembling the temporary assembly outside the setting device 600, the obtained temporary assembly is installed on the pedestal 610 of the setting device 600, but the setting is not limited to this. The temporary assembly may be assembled on the pedestal 610 of the device 600. Further, in the present embodiment, the temporary assembly process of step 10 and the installation process of step 20 correspond to the arrangement process.

[Insert process]
Subsequently, an insertion step of inserting the piston 620 into the temporary assembly installed on the pedestal 610 is executed (see step 30 and FIG. 17).

In step 30, first, the motion control unit 640 arranges the piston 620 on the rear end side of the temporary assembly temporarily installed on the pedestal 610. More specifically, the motion control unit 640 is located at a position vertically above the displacement detection needle 630 protruding from the pedestal 610 and above the rear end side end of the temporary assembly, at the tip of the piston 620. The piston 620 is moved so that the surface 623 is located. Then, in this state, the motion control unit 640 moves the piston 620 vertically downward to insert the piston 620 from the rear end side of the temporary assembly installed on the pedestal 610 into the inside thereof. .. At this time, the operation control unit 640 inserts the piston 620 until the tip surface 623 of the piston 620 comes into contact with the rear end side surface (fourth step portion 498) of the extension portion 49b of the pressurizing member 49. I will go.

In the case of the present embodiment, the tip surface 623 of the piston 620 first contacts the pressurizing member 49, then contacts the pressurizing member 49, and then further contacts the tip insulating member 43. Then, in the present embodiment, the initial dimensions and the initial shape (state before setting) of the pressurizing member 49 are determined so that the pistons 620 come into contact with each other in this order.

As the piston 620 is inserted into the temporary assembly in this way, the air existing inside the temporary assembly (more specifically, inside the pressurizing member 49) is removed. For example, it is discharged to the outside of the temporary assembly through a perforation 622 provided in the piston 620.

[Pressure process]
Then, using the pedestal 610 and the piston 620, a pressurizing step of pressurizing the temporary assembly is executed (see step 40 and FIG. 18).

In step 40, first, the motion control unit 640 controls the piston 620 to apply a force of a predetermined magnitude. Along with this, first, the pressurizing member 49 is pressurized through the piston 620, the pedestal 610, the diaphragm head 32, the first internal housing 35, and the first insulating member 51. Further, after the pressurizing member 49 is pressurized, following the pressurizing member 49, the diaphragm head 32 is pressurized via the piston 620, the tip insulating member 43, and the pedestal 610. That is, in this example, the pressurizing member 49 is set first and the diaphragm head 32 is set later as the temporary assembly is pressurized by using the piston 620 and the pedestal 610. It has become.

At this time, in the pressure member 49, the applied force is concentrated on the first tubular portion 491 (see FIG. 5), which is the smallest (thinnest) portion, and plastic deformation occurs at this portion. .. Then, the pressure member 49 is set by the plastic deformation of this portion. As described above, the first tubular portion 491 of the pressurizing member 49 is a portion that functions as a spring when the pressurizing member 49 applies a preload to the piezoelectric element 41.

On the other hand, in the diaphragm head 32, the applied force is concentrated in the vicinity of the back surface annular recess 32c, which is the smallest (thinnest) portion, and plastic deformation occurs at this portion. Then, the diaphragm head 32 is set by the plastic deformation of this portion. The portion of the diaphragm head 32 that is in the vicinity of the back surface annular recess 32c is a portion that functions as a spring when the diaphragm head 32 detects pressure, as described above.

In the pressurizing step of step 40, the front end surface 623 of the piston 620 comes into contact with the rear end side surface of the extending portion 49b of the pressurizing member 49 and the rear end side surface of the tip insulating member 43. In this example, the area of the tip surface of the piston 620 and the area of the tip end side of the tip electrode member 42 that is inserted into the pressurizing member 49 and comes into contact with the rear end side of the extending portion 49b of the pressurizing member 49 are substantially defined. The shape of the tip surface 623 of the piston 620 is defined so as to be equal.

When both the pressure member 49 and the diaphragm head 32 are plastically deformed (set) in this way, the surface of the pressure receiving surface 32a of the diaphragm head 32 located closer to the center of the back surface annular recess 32c. The central recess 32b protrudes toward the tip side more than before the plastic deformation occurs. Then, along with this, the displacement detection needle 630 that comes into contact with the surface center recess 32b of the diaphragm head 32 is pushed by the diaphragm head 32 and moves to the side that sinks with respect to the pedestal 610 (lower side in the drawing). To do. Then, when the movement amount of the displacement detection needle 630 reaches a predetermined threshold value, the motion control unit 640 stops the pressurization using the piston 620. At this time, the magnitude of the applied force is determined based on the magnitude of the yield load of both the pressurizing member 49 and the diaphragm head 32. The magnitude of the applied force is usually about 1.1 times the yield load of the target member.

Here, in the pressurizing step of step 40, the pressurizing member 49 is set first, and then the diaphragm head 32 is set for the following reason. In the case of the present embodiment, the rigidity of the pressurizing member 49 (actually, the first tubular portion 491) is higher than the rigidity of the diaphragm head 32 (actually, the periphery of the back surface annular recess 32c). Therefore, the force required to set the pressurizing member 49 is larger than the force required to set the diaphragm head 32 (details of this will be described later). Therefore, when a configuration is adopted in which the diaphragm head 32 is set before the pressurizing member 49, the diaphragm head 32 is set more than necessary when the pressurizing member 49 is set as much as necessary. turn into. Therefore, in the present embodiment, the pressurizing member 49 and the diaphragm head 32 are set in this order in one step (pressurizing step of step 40).

In the pressurizing step of the present embodiment, in addition to setting the pressurizing member 49 and the diaphragm head 32, two contacting members (for example, the first internal housing 35-1st insulating member 51, the first A process of crushing minute irregularities on the surface of each member existing at the contact portion of the insulating member 51-pressurizing member 49) is also performed. Further, in the present embodiment, the pressurizing step of step 40 corresponds to both the setting step and the double setting step.

[Pulling process]
Next, a pulling step of pulling out the piston 620 from the temporary assembly (both the pressurizing member 49 and the diaphragm head 32 are set) installed on the pedestal 610 is executed (see step 50 and FIG. 19).

In step 50, first, the motion control unit 640 moves the piston 620 in the direction opposite to the insertion step of step 30 (vertically upward). Along with this, the front end surface 623 of the piston 620 is separated from the rear end side surface of the tip insulating member 43 and the rear end side surface of the extension portion 49b of the pressurizing member 49.

Further, in step 50, before moving the piston 620 vertically upward, the operation control unit 640 uses a compressor (not shown) to send air from the outside into the perforation 622 of the piston 620. Along with this, air is introduced into the inside of the temporary assembly (more specifically, the inside of the pressurizing member 49) from the outside through the perforation 622 provided in the piston 620. As a result, in the temporary assembly, the tip insulating member 43, which exists inside the pressurizing member 49 and is in close contact with the tip surface 623 of the piston 620 in the pressurizing step of step 40, moves upward while being attached to the piston 620. It makes it difficult for the situation to move. In other words, the tip insulating member 43 can maintain the state of being loaded on the back surface central convex portion 32d of the diaphragm head 32 even if the piston 620 moves vertically upward.

Then, after the tip surface 623 of the piston 620 is removed from the rear end of the aggregate, the operation control unit 640 stops the movement of the piston 620 vertically upward and stops the air feeding using the compressor.

[Removal process]
Subsequently, a removal step of removing the aggregate from the setting device 600 is executed (step 60).

In step 60, the temporary assembly (both the pressurizing member 49 and the diaphragm head 32 are set) that has been fixed by using a jig (not shown) is removed from the pedestal 610 of the setting device 600. At this time, as described above, the temporary assembly is provided with the tip insulating member 43 in addition to the constituent members of the second structure.

[Welding process]
Finally, a welding step of obtaining a second structure is executed by welding the temporary assembly (both the pressure member 49 and the diaphragm head 32 are set) removed from the setting device 600 (the one in which both the pressurizing member 49 and the diaphragm head 32 are set). Step 70, see FIG. 20).

In step 70, the temporary assembly is installed in a laser welding apparatus (not shown). Then, the second welded portion W2 is formed by performing laser welding on the boundary portion between the first inner housing 35 and the second inner housing 36 of the temporary assembly over the entire circumference of the outer peripheral surface. By forming the second welded portion W2 in this way, the temporary assembly is formed with the first structure in which the diaphragm head 32 and the first internal housing 35 are integrated via the first welded portion W1. 1 The insulating member 51, the pressurizing member 49, the second insulating member 52, and the first internal housing 35 are integrated to form a second structure.

However, in this example, the tip insulating member 43 used in the setting is still attached to the inside of the second structure thus obtained. The tip insulating member 43 may be used as it is in the subsequent production of the fourth structure, or may be once removed from the second structure. However, considering that a certain degree of dimensional tolerance is allowed for the tip insulating member 43, the tip insulating member 43 is used as it is for the subsequent production of the fourth structure without removing the tip insulating member 43 from the obtained second structure. Is desirable.

[Fourth structure]
Then, the fourth structure including the above-mentioned second structure (see FIG. 20) and the above-mentioned third structure (piezoelectric module 400: see FIG. 9) will be described.

FIG. 21 is a cross-sectional view showing the configuration of the fourth structure.
The fourth structure includes a second structure, a tip insulating member 43 inserted into the inside of the second structure from the rear end side of the second structure, and a second structure from the rear end side of the second structure. The third structure (piezoelectric module 400) inserted inside the structure and on the rear end side of the tip insulating member 43, and the inside of the second structure and the third structure from the rear end side of the second structure. A support member 53 inserted into the rear end side is provided. Further, the fourth structure is integrated by the third welded portion W3 formed by laser welding the support member 53 and the pressurizing member 49 constituting the second structure over the entire circumference of the outer peripheral surface. There is.

In the present embodiment, when the fourth structure is manufactured, the piezoelectric module 400 including the third structure, that is, the piezoelectric element 41, and the support member 53 are attached to the second structure to which the tip insulating member 43 is temporarily attached. And are inserted in this order. Then, a predetermined preload is applied to the piezoelectric element 41 provided in the piezoelectric module 400 by applying a predetermined force between the front end side of the second structure and the rear end side of the support member 53. To do. The magnitude of the force applied at this time may be smaller than the force applied to set both the pressurizing member 49 and the diaphragm head 32 in the manufacturing procedure of the second structure. In the pressure detection device 20, a size sufficient is sufficient so that the piezoelectric element 41 does not rattle. Then, in a state where the piezoelectric element 41 is preloaded in this way, the support member 53 and the pressure member 49 are laser-welded to form the third welded portion W3, whereby the first structure including the first structure is included. A fourth structure is obtained in which the two structures, the third structure (piezoelectric module 400), the tip insulating member 43, and the support member 53 are integrated.

In the fourth structure thus obtained, both the diaphragm head 32 and the pressurizing member 49 are set, and the piezoelectric element 41 is passed through the set pressurizing member 49 or the like. Is given the desired preload. In the present embodiment, the procedure for manufacturing the fourth structure using the second structure or the like corresponds to the four steps of the applying step, the fixing step, the preload applying step, and the positioning step.

[About setting]
Here, the setting of the pressurizing member 49 and the diaphragm head 32 will be described with reference to specific examples.

(Setting with a single pressurizing member)
FIG. 22A is a graph showing the relationship between the displacement amount of the pressurizing member 49 and the applied load when the pressurizing member 49 used in the present embodiment is set as a single unit. In FIG. 22A, the horizontal axis is the displacement amount (μm) of the pressurizing member 49 in the center line direction, and the vertical axis is the load (N) applied to the pressurizing member 49. Further, FIG. 22A also shows the characteristics of the pressurizing member 49 before setting and the characteristics after setting.

As is clear from FIG. 22 (a), in this example, in order to appropriately set the pressure member 49, the displacement amount of the pressure member 49 should be about 40 (μm) to 60 (μm). Turns out to be necessary. It can also be seen that the load applied to the pressurizing member 49 at this time is about 400 (N) to 600 (N).

(Setting with the diaphragm head alone)
FIG. 22B is a graph showing the relationship between the displacement amount of the diaphragm head 32 and the applied load when the diaphragm head 32 used in the present embodiment is set by itself. In FIG. 22B, the horizontal axis is the displacement amount (μm) in the center line direction of the diaphragm head 32, and the vertical axis is the load (N) applied to the diaphragm head 32. Further, FIG. 22B also shows the characteristics of the diaphragm head 32 before setting and the characteristics after setting.

As is clear from FIG. 22B, in this example, in order to appropriately set the diaphragm head 32, it is necessary to set the displacement amount of the diaphragm head 32 to about 40 (μm) to 60 (μm). It can be seen that it is. It can also be seen that the load applied to the diaphragm head 32 at this time is about 100 (N) to 150 (N).

Therefore, from FIGS. 22 (a) and 22 (b), it can be seen that the force required for setting the pressurizing member 49 is larger than the force required for setting the diaphragm head 32. More specifically, it can be seen that the force required to set the pressurizing member 49 is about four times the force required to set the diaphragm head 32. Therefore, in the present embodiment, in the pressurizing step (see FIG. 13) of step 40 described above, the pressurizing member 49 is set first, and the diaphragm head 32 is set later.

(Setting both the pressurizing member and the diaphragm head together)
FIG. 23 is a graph showing the relationship between the displacement amount of the diaphragm head 32 and the applied load when both the pressurizing member 49 and the diaphragm head 32 are set together. Therefore, FIG. 23 corresponds to the case where the setting is performed by using the method adopted in the present embodiment. In FIG. 23, the horizontal axis is the displacement amount (μm) in the center line direction of the diaphragm head 32, and the vertical axis is the load (N) applied to the diaphragm head 32.

In this example, the position indicated by the coordinate (A) in the figure corresponds to the state before the setting is started (before the pressurizing step of step 40). At this time, the displacement amount is approximately 0 (μm), and the load is also approximately 0 (N).

Then, the pressurizing step of step 40 is started, and when the piston 620 is pushed in, the position moves from the coordinate (A) to the coordinate (B) in the figure. During this period, the piston 620 and the pressurizing member 49 are in contact with each other, while the piston 620 and the tip insulating member 43 are hardly in contact with each other. During this period, as the pressure member 49 is pushed by the piston 620, the pressure member 49 is plastically deformed, so that the pressure member 49 is set. In the coordinates (B), the magnitude of the force applied to the pressurizing member 49 is about 580 (N), which is large enough for the pressurizing member 49 to be set (FIG. 22). See also (a)).

When the position indicated by the coordinate (B) in the drawing is reached in the middle of the pressurizing step of step 40, the piston 620 comes into contact with the tip insulating member 43 in addition to the pressurizing member 49. And migrate. Then, the pressurizing step of step 40 is continued, and the piston 620 is further pushed in, so that the position moves from the coordinate (B) to the coordinate (C) in the figure. During this time, the piston 620 and the pressurizing member 49 are in contact with each other, and the piston 620 and the tip insulating member 43 are in contact with each other. During this period, as the tip insulating member 43 is pushed by the piston 620, the diaphragm head 32 pushed through the tip insulating member 43 is plastically deformed, so that the diaphragm head 32 is set. Further, during this period, the magnitude of the force applied to the pressure member 49 is larger than when it is at the coordinate (B), and the pressure member 49 is also plastically deformed. In the coordinates (C), the magnitude of the force applied to the diaphragm head 32 is about 100 (N) or more, which is sufficiently large for the diaphragm head 32 to be set (FIG. 22 (b)). See also). When the coordinate (C) is reached in the figure, the pressurizing step of step 40 ends.

Subsequently, the drawing step of step 50 is started, and the piston 620 is pulled out, so that the position moves from the coordinate (C) to the coordinate (D) in the drawing. During this period, the piston 620, the pressurizing member 49, and the diaphragm head 32 are not in contact with each other. During this period, as the pressurization on the pressurizing member 49 and the diaphragm head 32 is released, the pressurizing member 49 and the diaphragm head 32 try to return to their original states by elastic deformation. However, the coordinates (D), which is the final point when the pressurizing member 49 and the diaphragm head 32 are fully extended, are at the origin because the pressurizing member 49 and the diaphragm head 32 are plastically deformed due to the setting. The position is different from a certain coordinate (A). In this example, it can be seen that the position of the diaphragm head 32 in the center line direction is deviated by about 5 (μm) due to the setting of the pressurizing member 49 and the diaphragm head 32.

[Other]
In the present embodiment, the setting device 600 only sets the diaphragm head 32 and the pressurizing member 49, respectively, and welds the first internal housing 35 and the second internal housing 36 (second welded portion). The formation of W2) was performed by another laser welding device, but the present invention is not limited to this. For example, a laser welding head (not shown) is provided in the setting device 600, and the setting of the diaphragm head 32 and the pressurizing member 49 and the welding of the first internal housing 35 and the second internal housing 36 are continuously performed. It doesn't matter.

Further, in the present embodiment, the positive path and the housing path are electrically insulated by providing the tip insulating member 43 or the like, but the present invention is not limited to this, and the positive path is used. A configuration that electrically connects to the housing path may be adopted.

Further, in the present embodiment, the rod-shaped pressure detecting device 20 has been described as an example, but the present invention is not limited to this, and for example, a ring-shaped device (combustion pressure sensor) as described in Patent Document 2 may be used. You may apply it.

Further, in the present embodiment, the pressure member 49 having a tubular shape is used, the piezoelectric element 41 is housed inside the pressure member 49, and the pressure member 49, the components of the piezoelectric module 400, and the support member 53 are used. Was used to apply a preload to the piezoelectric element 41, but the present invention is not limited to this. That is, the shape of the pressurizing member 49 may be appropriately redesigned as long as the piezoelectric element 41 can be sandwiched from the front end side and the rear end side to apply a preload.

Further, in the present embodiment, the piston 620 is directly abutted against the pressurizing member 49 to set the pressurizing member 49, and the piston 620 is indirectly connected to the diaphragm head 32 via the tip insulating member 43. The diaphragm head 32 was set by abutting against the piston head 32, but the present invention is not limited to this. For example, the piston 620 may be abutted against the pressurizing member 49 via some member to set the pressurizing member 49. On the other hand, the piston 620 may be directly abutted against the diaphragm head 32 to set the diaphragm head 32.

Further, in the present embodiment, the piston 620 is used by directly abutting the piston 620 against the pressurizing member 49 and indirectly abutting the piston 620 against the diaphragm head 32 via the tip insulating member 43. Therefore, the pressurizing member 49 and the diaphragm head 32 were set in parallel. However, the present invention is not limited to this, and for example, a configuration is adopted in which the piston 620 is directly or indirectly abutted against the pressurizing member 49 and the pressurizing member 49 is directly or indirectly abutted against the diaphragm head 32. You may. On the contrary, for example, the piston 620 may be directly or indirectly abutted against the diaphragm head 32, and the diaphragm head 32 may be directly or indirectly abutted against the pressurizing member 49. Good. That is, the pressure member 49 and the diaphragm head 32 may be set in series by using the piston 620.

Further, in the present embodiment, in the pressurizing step of step 40 (see FIG. 13), both the pressurizing member 49 and the diaphragm head 32 are set together, but the present invention is not limited to this. .. In the pressurizing step of step 40, at least one of the pressurizing member 49 and the diaphragm head 32 may be set.

1 ... Pressure detection system, 10 ... Internal combustion engine, 20 ... Pressure detection device, 30 ... Housing, 31 ... Tip external housing, 32 ... Diaphragm head, 33 ... Intermediate external housing, 34 ... Rear end external housing, 35 ... 1st internal housing, 36 ... 2nd internal housing, 40 ... Detection mechanism, 41 ... Piezoelectric element, 42 ... Tip electrode member, 43 ... Tip insulating member, 44 ... Rear end electrode member, 45 ... Rear end Insulating member, 46 ... 1st coil spring, 47 ... Conducting member, 48 ... Holding member, 49 ... Pressurizing member, 50 ... Insulating tube, 51 ... 1st insulating member, 52 ... Second insulating member, 53 ... Supporting member, 54 ... 2nd coil spring, 55 ... 1st accommodating member, 56 ... 2nd accommodating member, 57 ... circuit built-in member, 58 ... connecting member, 59 ... closing member, 60 ... 3rd insulating member, 70 ... sealing part, 80 ... connecting Cable, 100 ... Control device, 400 ... Piezoelectric module, 600 ... Setting device, 610 ... Pedestal, 620 ... Piston, 630 ... Displacement detection needle, 640 ... Motion control unit

Claims (15)

A pressure detection device including a piezoelectric element that outputs an electric signal corresponding to a pressure received from the outside along the axial direction, and a spring member that has elasticity and applies a pressing force along the axial direction to the piezoelectric element. It is a manufacturing method of
A setting step of setting the spring member by pressing a pressing member that applies a pressing force from the other end side in the axial direction toward the one end side to the one end side of the spring member.
A method for manufacturing a pressure detection device, which includes a step of applying a pressing force to the piezoelectric element by using the spring member by positioning the piezoelectric element and the set spring member. The spring member is a pressure member that pressurizes the piezoelectric element in order to apply a preload as a pressing force to the piezoelectric element by sandwiching the piezoelectric element from one end side and the other end side. The method for manufacturing a pressure detector according to claim 1. The pressurizing member has a tubular shape due to the provision of through holes along the axial direction.
The claim is characterized in that, in the setting step, the pressing member is brought into contact with the inner peripheral surface of the pressing member on one end side in a state where the pressing member is inserted into the through hole of the pressing member. Item 2. The method for manufacturing a pressure detector according to item 2. In the applying step, the pressing member is pulled out from the inside of the through hole in the pressurizing member, and the piezoelectric element is housed inside the through hole, and the pressurizing member is used to the one end side and the above. The method for manufacturing a pressure detecting device according to claim 3, wherein the piezoelectric element is sandwiched from the other end side. In the applying step, one end side of the piezoelectric element is abutted against the inner peripheral surface of the pressurizing member, and the other end side of the piezoelectric element is abutted against the abutting member.
The pressure detecting device according to claim 4, further comprising a fixing step of fixing the pressurizing member and the abutting member in a state where the preload is applied to the piezoelectric element after the applying step. Manufacturing method. The method for manufacturing a pressure detecting device according to claim 1, wherein the spring member is a pressure receiving member provided on one end side of the piezoelectric element and receiving a pressure transmitted to the piezoelectric element from the outside. In the setting step, a pressure transmitting member for transmitting the pressure received by the pressure receiving member to the piezoelectric element is arranged on the rear end side of the pressure receiving member, and the pressing member is brought into contact with the pressure transmitting member. The method for manufacturing a pressure detecting device according to claim 6, wherein the pressure receiving member is pushed from the pressing member via the pressure transmitting member. In the applying step, the pressing member is removed from the other end side of the pressure receiving member, and the pressure transmitting member and the piezoelectric element are arranged in this order on the other end side of the pressure receiving member. The method for manufacturing a pressure detecting device according to claim 7, wherein the piezoelectric element is sandwiched between the one end side and the other end side using the above. The method according to any one of claims 1 to 8, wherein the magnitude of the pressing force applied in the applying step is smaller than the magnitude of the pressing force applied by the pressing member in the setting step. A method for manufacturing a pressure detector. An arrangement step of arranging a pressurizing member extending along the axial direction from one end side to the other end side and arranging a pressure receiving member receiving pressure from the outside on the one end side of the pressurizing member.
By pressing a pressing member that applies a pressing force from the other end side toward the one end side against the one end side of the pressurizing member and the other end side of the pressure receiving member, the pressurizing member and the pressure receiving member Double setting process that sets both of
A piezoelectric element that outputs an electric signal corresponding to a pressure received from the outside is sandwiched between the one end side and the other end side by using the pressurizing member to apply a preload to the piezoelectric element. Process and
A method for manufacturing a pressure detecting device, which includes a positioning step of positioning the piezoelectric element by directly or indirectly bringing the pressure receiving member and the piezoelectric element to which the preloaded is applied into contact with each other via another member. .. The pressure detection device according to claim 10, wherein in the double setting step, the pressing member first presses against the pressing member, and then presses against the pressure receiving member. Production method. The method for manufacturing a pressure detecting device according to claim 10 or 11, wherein the pressure member and the pressure receiving member are made of the same material. Claims 10 to 12 are characterized in that the magnitude of the force corresponding to the preload applied in the preload applying step is smaller than the magnitude of the pressing force applied by the pressing member in the double setting step. The method for manufacturing a pressure detector according to any one of the above items. The method for manufacturing a pressure detecting device according to any one of claims 10 to 13, wherein the piezoelectric element has a piezoelectric body made of an inorganic single crystal. The method for manufacturing a pressure detection device according to claim 14, wherein the piezoelectric body is a Langasite-based single crystal.

Images