JP2017173122A - Pressure detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress overlapping of external noise on an output from a detection element and suppress change in a weight given to the detection element.SOLUTION: A pressure detection device 20 includes: a cylindrical end-side housing (first and second end-side housings 311 and 312); a piezoelectric element 41 housed in the end-side housing; a pressurization member 49 and a supporting member 50 that house the piezoelectric element 41 therein and are housed inside the end-side housing, and pinch the piezoelectric element to thereby give the piezoelectric element 41 a weight; a diaphragm head 32 that is attached to an end side of the end-side housing; an insulation membrane 42a provided between the diaphragm head 32 and the piezoelectric element 41; an insulation membrane 49a provided in contact with the end-side housing and the pressurization member 49 inside the end-side housing; and a striking pipe 57 that fixes the pressurization member 49 to the end-side housing in a state in which the pressurization member is electrically insulated from the diaphragm head 32 and the end-side housing.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a pressure detection device that detects pressure using a detection element.

  As an apparatus for detecting the pressure in a combustion chamber of an internal combustion engine or the like, an apparatus using a detection element such as a piezoelectric element has been proposed.

  For example, Patent Document 1 discloses a cylindrical housing, a diaphragm attached to the front end side of the housing, a piezoelectric element that is disposed on the rear end side of the diaphragm in the housing and detects pressure acting through the diaphragm, and a housing A first electrode portion provided in contact with both of the diaphragm and the piezoelectric element in the inside, a second electrode portion provided in contact with the piezoelectric element on the rear end side of the piezoelectric element in the housing, An insulating ring provided in contact with the second electrode on the rear end side of the second electrode portion in the housing, a support member provided in contact with the insulating ring on the rear end side of the insulating ring in the housing, and the housing The first electrode part, the piezoelectric element, the second electrode part, the insulating ring and the support member are accommodated inside the housing, and the first electrode part is By toward the axial direction of the ring is secured to the support member to pressurize the pressure detecting device provided with a pressure member for applying a load to the piezoelectric element is described.

JP 2013-205307 A

Here, when noise enters the inside from the outside of the pressure detection device, the noise is superimposed on the output from the detection element. When noise is superimposed in this manner, an error in the detected pressure becomes large.
In this type of pressure detection device, a predetermined load is applied to the detection element. However, if the positioning of the detection element with respect to the casing of the pressure detection device is insufficient, the load applied to the detection element varies, and the error in the detected pressure increases.
An object of the present invention is to suppress the superimposition of noise from the outside on the output from the detection element, and to suppress the fluctuation of the load applied to the detection element.

The pressure detection device of the present invention includes a cylindrical casing, a detection element that is housed in the casing and detects a change in pressure from the front end side to the rear end side of the casing, and the detection element And an attachment member for applying a load to the detection element by sandwiching the detection element from the front end side and the rear end side, and attached to the front end side of the casing A deformable member that is deformed by receiving pressure from the outside, and a pressure that is provided between the deformable member and the detection element that is insulative and is inside the housing, and acts on the deformable member An insulating transmission portion that transmits the detection element to the detection element, an insulating portion that is insulative and provided in contact with the casing and the applying member inside the casing, and the applying member includes the deforming member. And electrically insulated from the housing And a fixing member for fixing to the housing.
Here, the imparting member has a cylindrical shape and includes a projecting portion projecting outward on an outer peripheral surface, and the fixing member is disposed between the inner peripheral surface of the housing via the insulating portion. The application member may be fixed to the housing by sandwiching the protruding portion.
Further, the applying member is disposed outside the detection element, is electrically connected to the front end side of the detection element, and is electrically insulated from the rear end side of the detection element, from the front end side of the detection element A first application member for applying a load; and a first application member provided on a rear end side of the first application member, electrically connected to the first application member and electrically insulated from the detection element, It is good to have the 2nd provision member which provides a load from the rear end side of the detection element by being fixed to.
And a conductive member that is housed inside the application member and electrically connected to a rear end side of the detection element to conduct a detection signal output by the detection element. It is preferable that the detection element is grounded by being electrically connected to the distal end side of the detection element and electrically insulated from the conductive member.
From another point of view, the pressure detection device according to the present invention is attached to a cylindrical casing and the front end side of the casing, is electrically connected to the casing, and receives pressure from the outside. A deforming member that deforms in a deformed manner, a detection element that is provided in the rear end side of the deforming member inside the housing and detects pressure acting through the deforming member, and an inside of the housing. It is provided between the deformation member and the detection element, is electrically connected to the detection element, is electrically insulated from the deformation member, and transmits pressure acting via the deformation member to the detection element. And a first transmission member that constitutes a first electrical path of the detection element, a first transmission member that is provided inside the housing and on a rear end side of the detection element, is electrically connected to the detection element, and the first 1 is electrically insulated from the transmission member, and the detection element A second transmission member that constitutes an electrical path; and is provided inside the housing and accommodates the detection element, the first transmission member, and the second transmission member, and is electrically connected to the first transmission member. An applying member that is connected and electrically insulated from the second transmission member, applies a load to the detection element via the first transmission member and the second transmission member, and constitutes the first electric path; And a fixing member that fixes the application member to the casing in a state of being electrically insulated from the deformation member and the casing.

  ADVANTAGE OF THE INVENTION According to this invention, while superimposing the noise from the outside with respect to the output from a detection element, the fluctuation | variation of the load provided to a detection element can be suppressed.

It is a schematic block diagram of the pressure detection system which concerns on embodiment. It is a side view of a pressure detection apparatus. It is sectional drawing (III-III sectional drawing of FIG. 2) of a pressure detection apparatus. It is an expanded sectional view of the tip side of a pressure detection device. It is a perspective view of a pressurizing member. It is a perspective view of a storage member.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
[Configuration of pressure detection system]
FIG. 1 is a schematic configuration diagram of a pressure detection system 1 according to an embodiment.
The pressure detection system 1 detects the pressure (combustion pressure) in the combustion chamber C in the internal combustion engine 10, and supplies power to the pressure detection device 20 and based on the pressure detected by the pressure detection device 20. A control device 80 that controls the operation of the internal combustion engine 10 and a connection cable 90 that electrically connects the pressure detection device 20 and the control device 80 are provided.

  Here, the internal combustion engine 10 to be pressure-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. The cylinder head 13 is configured. Further, the cylinder head 13 is provided with a communication hole 13a that allows the combustion chamber C to communicate with the outside. And while inserting the front end side of the pressure detection apparatus 20 in this communicating hole 13a, the rib part 312b (refer FIG. 2 mentioned later) provided in the pressure detection apparatus 20 is fixed to the cylinder head 13, thereby making the internal combustion engine. The pressure detection device 20 is attached to 10. 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 detection device 20. FIG. 3 is a cross-sectional view of the pressure detection device 20 (III-III cross-sectional view of FIG. 2). FIG. 4 is an enlarged cross-sectional view of the front end side of the pressure detection device 20.

  The pressure detection device 20 according to the present embodiment includes a casing 30 exposed to the outside and various mechanisms for detecting pressure, and is almost entirely housed in the casing 30 and partially (a connection described later) The detection mechanism part 40 provided so that the member 54) may be exposed outside, and the seal part 70 attached to the outer peripheral surface of the housing | casing part 30 are provided. The pressure detection device 20 has a left side in FIG. 2 (a portion where the casing 30 is exposed) facing the combustion chamber C (lower side in FIG. 1) with respect to the internal combustion engine 10 shown in FIG. Is attached so that the right side (the portion where the detection mechanism 40 is exposed) faces outward (upward in FIG. 1). Further, in this state, the seal portion 70 is positioned inside the communication hole 13 a provided in the cylinder head 13. In the following description, in FIG. 2, the side toward the left in the drawing is referred to as the “front end side” of the pressure detection device 20, and the side toward the right in the drawing is referred to as the “rear end side” of the pressure detection device 20. In the following description, the center line direction of the pressure detection device 20 indicated by a one-dot chain line in FIG. 2 is simply referred to as a center line direction.

[Configuration of the casing]
The housing unit 30 includes a front end side housing 31, a diaphragm head 32 attached to the front end side of the front end side housing 31, and a rear end side housing 33 attached to the rear end side of the front end side housing 31. It has. Here, in the present embodiment, the front end side casing 31 and the rear end side casing 33 function as an example of a casing, and the diaphragm head 32 functions as an example of a deformable member.

(Front side housing)
The front end side housing 31 is a member having a hollow structure and exhibiting a tubular shape as a whole. The distal end side casing 31 is made of a metal material such as stainless steel having conductivity and high heat resistance and acid resistance.

  The distal end side casing 31 includes a first distal end side casing 311 positioned relatively on the distal end side and a second distal end side casing 312 positioned relatively on the rear end side. Here, in the distal end side casing 31, both the outer peripheral surface on the rear end side of the first distal end side casing 311 and the inner peripheral surface on the distal end side of the second distal end side casing 312 are laser-welded. Is configured to be integrated. The diaphragm head 32 is attached to the front end side of the first front end side housing 311 by laser welding, and the rear end side housing 33 is fitted to the rear end side of the second front end side case 312 by fitting. It is attached.

  Here, a concave portion 311 a for mounting a first seal member 71 (details will be described later) constituting the seal portion 70 is provided on the outer peripheral surface of the first distal end side housing 311. Further, inside the first front end side housing 311, there are a part set to the first diameter on the front end side and a part set to a second diameter larger than the first diameter on the rear end side. There is an inner step 311b connecting the two parts at the boundary between these two parts.

  On the other hand, the outer peripheral surface of the second distal end side housing 312 is provided with a concave portion 312a for mounting a second seal member 72 (details will be described later) constituting the seal portion 70 together with the first seal member 71. . Further, on the outer peripheral surface of the second front end side housing 312, a ring-shaped rib portion 312 b protruding outward is provided on the rear end side of the recess 312 a. As described above, the rib portion 312b is used to fix the pressure detection device 20 to the internal combustion engine 10 (more specifically, the cylinder head 13).

(Diaphragm head)
The diaphragm head 32 is a member having a disk shape as a whole. The diaphragm head 32 is made of a metal material such as stainless steel having conductivity and high heat resistance and acid resistance. In particular, in this example, the diaphragm head 32 and the distal end side casing 31 are made of the same material.

  The diaphragm head 32 has a concave portion 32b formed at the central portion on the tip side, a pressure receiving surface (surface) 32a that receives pressure by being exposed to the outside (combustion chamber C side), and a back side of the pressure receiving surface 32a. A concave portion 32c provided by cutting the back surface into a ring shape, and a convex portion 32d protruding to the rear end side from the central portion (formation portion of the concave portion 32b) of the pressure receiving surface 32a due to the presence of the concave portion 32c. have. The diaphragm head 32 is provided so as to close the opening on the distal end side of the first distal end side housing 311. Laser welding is performed on the boundary between the diaphragm head 32 and the first distal end side housing 311 over the entire circumference of the outer peripheral surface.

(Rear end housing)
The rear end side housing 33 is a member having a hollow structure and exhibiting a tubular shape as a whole. The rear end housing 33 is made of a metal material such as stainless steel having conductivity and high heat resistance and acid resistance. However, in a state where the pressure detection device 20 is mounted on the internal combustion engine 10, the rear end side housing 33 is located outside the internal combustion engine 10, and thus has higher heat resistance and acid resistance than the front end side housing 31 described above. Low materials can be used.

  The rear end side housing 33 includes a first rear end side housing 331 positioned relatively on the front end side and a second rear end side housing 332 positioned relatively on the rear end side. Here, in the rear end side casing 33, the outer peripheral surface on the front end side of the second rear end side casing 332 is fitted into the inner peripheral surface on the rear end side of the first rear end side casing 331, thereby It is configured to be integrated. The front end side casing 31 (more specifically, the second front end side casing 312) is attached to the front end side of the first rear end side casing 331 by fitting, and the second rear end side casing is also mounted. A connecting member 54 (details will be described later) is attached to the rear end side of 332 by fitting.

[Configuration of detection mechanism]
The detection mechanism unit 40 includes a piezoelectric element 41, a tip electrode member 42, a first rear end electrode member 43, and a second rear end electrode member 44. The detection mechanism unit 40 includes an insulating ring 45, a first coil spring 46, a conductive member 47, and a holding member 48. Further, the detection mechanism unit 40 includes a pressure member 49, a support member 50, a second coil spring 51, and a housing member 52. Furthermore, the detection mechanism unit 40 includes a circuit board 53, a connection member 54, a ground plate 55, and an O-ring 56. Further, the detection mechanism unit 40 includes an abutment pipe 57. The detection mechanism unit 40 includes an insulating pipe 60, a first insulating member 61, a second insulating member 62, and a third insulating member 63. Here, in the present embodiment, the pressure member 49 and the support member 50 function as an example of the applying member, and the first rear end electrode member 43 and the second rear end electrode member 44 are the second transmission member. Functions as an example.

(Piezoelectric element)
The piezoelectric element 41 as an example of the detection element is a member having a cylindrical shape as a whole. The piezoelectric element 41 includes a piezoelectric body that exhibits the piezoelectric action of the piezoelectric longitudinal effect. The piezoelectric longitudinal effect means that when an external force is applied to the stress application axis in the same direction as the charge generation axis of the piezoelectric body, charges are generated on the surface of the piezoelectric body in the charge generation axis direction. The piezoelectric element 41 is disposed inside the front end side casing 31 and on the rear end side of the diaphragm head 32. The piezoelectric element 41 is accommodated in the distal end side casing 31 so that the center line direction is the direction of the stress application axis. Here, the piezoelectric element 41 is disposed inside the pressurizing member 49 provided inside the distal end side housing 31 and inside the insulating pipe 60 provided inside the pressurizing member 49. . The outer diameter of the piezoelectric element 41 is slightly smaller than the inner diameter of the insulating pipe 60 that accommodates the piezoelectric element 41 inside. The front surface of the piezoelectric element 41 is in contact with the rear surface of the front electrode member 42. On the other hand, the rear end surface of the piezoelectric element 41 is in contact with the front end surface of the first rear end electrode member 43. The outer peripheral surface of the piezoelectric element 41 is opposed to the inner peripheral surface of the insulating pipe 60. Thus, by providing the insulating pipe 60 between the inner peripheral surface of the pressurizing member 49 and the outer peripheral surface of the piezoelectric element 41, the pressurizing member 49 and the piezoelectric element 41 are not in direct contact.

  Next, a case where the piezoelectric lateral effect is used for the piezoelectric element 41 will be exemplified. The piezoelectric lateral effect means that when an external force is applied to a stress application axis at a position orthogonal to the charge generation axis of the piezoelectric body, charges are generated on the surface of the piezoelectric body in the charge generation axis direction. A plurality of thinly formed piezoelectric bodies may be laminated, and by laminating in this way, the charge generated in the piezoelectric bodies 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 using a langasite crystal (a langasite, langagate, langanite, LTGA) having a piezoelectric longitudinal effect and a piezoelectric transverse effect, crystal, gallium phosphate, or the like. can do. In the piezoelectric element 41 of the present embodiment, an LTGA single crystal is used as the piezoelectric body.

(Tip electrode member)
The tip electrode member 42 as an example of the first transmission member is a member having a cylindrical shape as a whole. The tip electrode member 42 is made of a metal material such as stainless steel having electrical conductivity and high heat resistance. In addition, an insulating film 42a formed by coating an insulating ceramic material containing alumina, zirconia, or the like is formed at the center portion of the tip electrode surface of the tip electrode member 42. Here, the insulating film 42a as an example of the insulating transmission portion has, for example, a circular shape, and the diameter thereof is larger than the diameter of the convex portion 32d provided on the back surface of the diaphragm head 32, and the pressure is increased. The diameter of the opening provided on the tip side of the member 49 is smaller.

  The tip electrode member 42 is disposed inside a pressurizing member 49 provided in the tip side casing 31. The front electrode member 42 is disposed on the rear end side of the diaphragm head 32 and on the front end side of the piezoelectric element 41. However, unlike the piezoelectric element 41 described above, the tip electrode member 42 is not accommodated in the insulating pipe 60. Further, the outer diameter of the tip electrode member 42 is slightly smaller than the inner diameter of the pressure member 49 that accommodates the tip electrode member 42 therein. And the area | region of the center part in which the insulating film 42a was provided among the surfaces of the front end side of the front end electrode member 42 is in contact with the surface of the rear end side of the convex part 32d provided in the back surface of the diaphragm head 32. Yes. In addition, the peripheral edge region where the insulating film 42 a is not provided in the tip-side surface of the tip electrode member 42 is in contact with the surface on the back side of the opening provided on the tip side of the pressure member 49. . On the other hand, the rear end surface of the front electrode member 42 is in contact with the front end surface of the piezoelectric element 41. In addition, the outer peripheral surface of the tip electrode member 42 is opposed to the inner peripheral surface of the pressure member 49.

(First rear end electrode member)
The first rear end electrode member 43 is a member having a disk shape as a whole. The first rear end electrode member 43 is made of a metal material such as stainless steel having conductivity, high heat resistance, and small thermal expansion difference from the piezoelectric element 41.

  The first rear end electrode member 43 is disposed inside a pressure member 49 provided inside the front end side casing 31. The first rear end electrode member 43 is disposed on the rear end side of the piezoelectric element 41 and on the front end side of the second rear end electrode member 44. Here, the first rear end electrode member 43 is disposed inside the insulating pipe 60 provided inside the pressurizing member 49. Further, the outer diameter of the first rear end electrode member 43 is substantially the same as the outer diameter of the piezoelectric element 41 and is slightly smaller than the inner diameter of the insulating pipe 60. The front end surface of the first rear end electrode member 43 is in contact with the rear end surface of the piezoelectric element 41. On the other hand, the rear end surface of the first rear end electrode member 43 is in contact with the front end surface of the second rear end electrode member 44. In addition, the outer peripheral surface of the first rear end electrode member 43 is opposed to the inner peripheral surface of the insulating pipe 60. Thus, by providing the insulating pipe 60 between the inner peripheral surface of the pressurizing member 49 and the outer peripheral surface of the first rear end electrode member 43, the pressurization member 49 and the first rear end electrode member 43 are There is no direct contact.

(Second rear end electrode member)
The second rear end electrode member 44 is a member that exhibits a top-like shape as a whole and has a T-shaped cross section. The second rear end electrode member 44 is made of a metal material such as stainless steel having conductivity and high heat resistance. The second rear end electrode member 44 has a disk-like body portion 44a positioned on the front end side, and a columnar shape, and a central portion on the rear end side surface of the main body portion 44a from the rear end side toward the rear end side. A first convex portion 44b that protrudes and a second convex portion 44c that has a cylindrical shape and protrudes further toward the rear end side from the rear end of the first convex portion 44b are provided. Here, the diameter of the first convex portion 44b is smaller than the diameter of the main body portion 44a, and the diameter of the second convex portion 44c is smaller than the diameter of the first convex portion 44b.

  The second rear end electrode member 44 is disposed inside a pressure member 49 provided in the front end side casing 31. Here, the front end side of the main body 44 a of the second rear end electrode member 44 is disposed inside the insulating pipe 60 provided inside the pressurizing member 49. On the other hand, a portion of the second rear end electrode member 44 that is on the rear end side than this is disposed outside the insulating pipe 60. Further, the outer diameter of the main body 44 a in the second rear end electrode member 44 is substantially the same as the outer diameter of the piezoelectric element 41 and is slightly smaller than the inner diameter of the insulating pipe 60. The front end surface of the main body 44 a of the second rear end electrode member 44 is in contact with the rear end surface of the first rear end electrode member 43. On the other hand, the rear end surface of the main body 44 a is in contact with the front end surface of the insulating ring 45. Further, the outer peripheral surface of the first convex portion 44b in the second rear end electrode member 44 is in contact with the inner peripheral surface of the insulating ring 45 at the front end side, and the rear end side is the inner periphery of the support member 50 via the air gap. Face to face. Furthermore, the outer peripheral surface of the second convex portion 44c in the second rear end electrode member 44 faces the inner peripheral surface of the support member 50 through the air gap, and the first coil spring 46 mounted on the outer peripheral surface. The conductive member 47 is in contact via As described above, by providing the insulating pipe 60, the air gap, and the insulating ring 45 between the inner peripheral surface of the pressurizing member 49 and the outer peripheral surface of the second rear end electrode member 44, The rear end electrode member 44 is not in direct contact. Further, by providing an air gap between the inner peripheral surface of the support member 50 and the outer peripheral surface of the second rear end electrode member 44, the support member 50 and the second rear end electrode member 44 are in direct contact with each other. do not do.

(Insulation ring)
The insulating ring 45 is a member having an annular shape as a whole. The insulating ring 45 is made of a ceramic material such as alumina that has insulating properties and high heat resistance.

  The insulating ring 45 is disposed inside a pressurizing member 49 provided inside the distal end side housing 31. The insulating ring 45 is located on the rear end side of the main body 44 a of the second rear end electrode member 44 and on the front end side of the support member 50. Here, inside the through hole provided in the insulating ring 45, the first convex portion 44b of the second rear end electrode member 44 is disposed. Further, the outer diameter of the insulating ring 45 is slightly smaller than the inner diameter of the pressure member 49. Furthermore, the inner diameter of the through hole of the insulating ring 45 is slightly larger than the outer diameter of the first convex portion 44 b in the second rear end electrode member 44. The front end surface of the insulating ring 45 is in contact with the rear end surface of the main body 44 a of the second rear end electrode member 44. On the other hand, the rear end surface of the insulating ring 45 is in contact with the front end surface of the support member 50. In addition, the outer peripheral surface of the insulating ring 45 is opposed to the inner peripheral surface of the pressing member 49. Furthermore, the inner peripheral surface of the insulating ring 45 is opposed to the outer peripheral surface of the first convex portion 44 b in the second rear end electrode member 44.

(First coil spring)
The first coil spring 46 is a member having 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 brass having conductivity and higher conductivity than the front end side housing 31, and the surface thereof is plated with gold.

  The first coil spring 46 is provided inside the distal end side housing 31 and is arranged inside the pressure member 49 and inside the support member 50. The first coil spring 46 is disposed on the rear end side of the second rear end electrode member 44 and on the front end side of the conductive member 47. That is, the first coil spring 46 is disposed across the second rear end electrode member 44 and the conductive member 47. Here, the front end side of the first coil spring 46 is wound around the second convex portion 44 c of the second rear end electrode member 44, and the rear end side of the first coil spring 46 is provided on the front end side of the conductive member 47. The tip end side recess 47a is inserted. The inner diameter of the first coil spring 46 is larger than the outer diameter of the second convex portion 44 c in the second rear end electrode member 44 and smaller than the inner diameter of the first convex portion 44 b. On the other hand, the outer diameter of the first coil spring 46 is smaller than the inner diameter of the tip-side recess 47 a in the conductive member 47. As a result, the front end of the first coil spring 46 abuts on the boundary portion (step portion) between the first convex portion 44 b and the second convex portion 44 c in the second rear end electrode member 44, and the front end side of the first coil spring 46 Is in contact with the outer peripheral surface of the second convex portion 44 c in the second rear end electrode member 44. On the other hand, the rear end of the first coil spring 46 is in contact with the bottom of the front end side recess 47 a of the conductive member 47, and the rear end side of the first coil spring 46 is the inner peripheral surface of the front end side concave portion 47 a of the conductive member 47. In contact with. In addition, the outer periphery of the first coil spring 46 faces the inner peripheral surface of the support member 50 through an air gap. Thus, by providing an air gap between the inner peripheral surface of the support member 50 and the first coil spring 46, the support member 50 and the first coil spring 46 do not directly contact each other.

(Conductive 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 the surface thereof is plated with gold. The conductive member 47 is provided with the above-described front end side recess 47a at the front end, and the rear end side is smaller in diameter than the central portion in the center line direction and protrudes toward the rear end side at the rear end. A convex portion 47b is provided.

  The conductive member 47 is provided inside the front end side casing 31, and almost all portions except the front end portion and the rear end portion (rear end side convex portion 47 b) are arranged inside the holding member 48. Yes. Further, the leading end side of the conducting member 47 is inside the pressure member 49, the trailing end side of the conducting member 47 is inside the accommodating member 52, and the intermediate portion located between the leading end side and the trailing end side is the second coil spring. 51, respectively. The conductive member 47 is disposed on the rear end side of the first coil spring 46 and on the front end side of the circuit board 53. The conductive member 47 is disposed so as to penetrate a through hole provided in the holding member 48 along the center line direction. The outer diameter of the leading end portion of the conductive member 47 (the portion not covered by the holding member 48) is larger than the inner diameter of the holding member 48 and smaller than the inner diameter of the support member 50. Further, the outer diameter of the rear end portion (rear end side convex portion 47 b) of the conductive member 47 is substantially the same as the inner width of the holding portion provided in the holding member 48. Furthermore, the outer diameter of the central portion in the center line direction of the conductive member 47 is substantially the same as the inner diameter of the holding member 48. The rear end side of the first coil spring 46 is inserted into the front-end-side recess 47 a of the conductive member 47 so as to be in contact with the first coil spring 46. On the other hand, the rear end convex portion 47 b of the conductive member 47 is fitted in a holding portion provided in the holding member 48. Further, the outer peripheral surface of the leading end portion of the conductive member 47 is opposed to the inner peripheral surface of the support member 50 through an air gap. Further, the outer peripheral surface of the central portion in the center line direction of the conductive member 47 faces the second coil spring 51 via the holding member 48 and the air gap. Furthermore, the outer peripheral surface of the rear end portion of the conductive member 47 is opposed to the outer peripheral surface of the housing member 52 through the air gap and the holding member 48. Thus, by providing the air gap and the holding member 48 between the inner peripheral surface of the support member 50 and the outer peripheral surface of the conductive member 47, the support member 50 and the conductive member 47 are not in direct contact. Further, by providing the air gap and the holding member 48 between the inner peripheral surface of the second coil spring 51 and the outer peripheral surface of the conductive member 47, the second coil spring 51 and the conductive member 47 are not in direct contact. Furthermore, by providing an air gap between the inner circumferential surface of the housing member 52 and the outer circumferential surface of the conducting member 47, the housing member 52 and the conducting member 47 are not in direct contact.

(Holding member)
The holding member 48 is a member formed by integrating a cylindrical portion located on the front end side and a plate-like portion located on the rear end side. The holding member 48 includes a base material made of a synthetic resin material such as PPT (Polypropylene Terephthalate) having insulation properties, wiring and terminals made of a metal material such as conductive copper, and the like. Contains. A conductive member 47 is accommodated in a cylindrical portion located on the front end side of the holding member 48, and a circuit board 53 is mounted on a plate-like portion located on the rear end side of the holding member 48. As described above, the holding member 48 has a function of holding the conductive member 47 and the circuit board 53.

  Of the holding member 48, a portion (outer peripheral surface) facing the support member 50, the second coil spring 51, and the housing member 52 is made of a synthetic resin material, and the metal material is not exposed to this portion. . In addition, a portion (inner peripheral surface) of the holding member 48 facing the intermediate portion located between the front end portion and the rear end portion of the conductive member 47 is also made of a synthetic resin material. The material is not exposed. Further, on the rear end side of the cylindrical portion of the holding member 48, a holding portion that is made of a metal material and that fits and holds the rear end convex portion 47 b of the conductive member 47 is provided. A wiring for electrically connecting to a signal input terminal (not shown) of the circuit board 53 is attached to the holding portion.

  The holding member 48 is provided across the inside of the front end side casing 31 and the inside of the rear end side casing 33. Further, the front end side of the holding member 48 is inside the pressurizing member 49, the rear end side of the conductive member 47 is inside the accommodating member 52, and an intermediate portion located between the front end side and the rear end side is the second coil spring. 51, respectively. The holding member 48 is disposed on the rear end side of the insulating ring 45 and on the front end side of the connection member 54.

  The outer diameter of the cylindrical portion located on the front end side of the holding member 48 is smaller than the inner diameter of the support member 50, and the outer diameter of the plate-like portion located on the rear end side of the covering member is accommodated in this portion. It is smaller than the inner diameter of the member 52. Further, the outer peripheral surface on the distal end side of the cylindrical portion of the holding member 48 is opposed to the inner peripheral surface of the support member 50 and the inner peripheral surface of the second coil spring 51 through an air gap. Further, the outer peripheral surface of the rear end side of the cylindrical portion of the holding member 48 and the outer peripheral surface of the plate-like portion are in contact with the inner peripheral surface of the storage member 52 or through the air gap. Face to face.

(Pressure member)
The pressurizing member 49 as an example of the first applying member is a member having a cylindrical shape as a whole. The pressure member 49 is made of a metal material such as stainless steel having electrical conductivity and high heat resistance.

  FIG. 5 is a perspective view of the pressure member 49. Hereinafter, the configuration of the pressing member 49 will be described with reference to FIG. In FIG. 5, 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.

  The pressurizing member 49 according to the present embodiment includes a front end tubular portion 491 that is located on the most distal end side and that is provided with an opening at the front end, and an intermediate tubular portion that is disposed on the rear end side of the front end tubular portion 491. 492 and a rear end cylindrical portion 493 that is located at the rear end side and the rearmost end side of the intermediate cylindrical portion 492. In the pressure member 49, the outer cylindrical portion 492 has an outer diameter larger than that of the front end cylindrical portion 491 and the rear end cylindrical portion 493, and the outer end of the rear end cylindrical portion 493 is larger than the front end cylindrical portion 491. The diameter is larger. The pressure member 49 includes a front end step portion 49b that connects the front end tubular portion 491 and the intermediate tubular portion 492, and a boundary portion between the intermediate tubular portion 492 and the rear end tubular portion 493. And a rear end stepped portion 49c for connecting the two. The inner diameter of the pressing member 49 is the same size except for the opening provided at the tip. Therefore, in this pressure member 49, the thickness of the intermediate cylindrical portion 492 is larger than the thickness of the rear end cylindrical portion 493, and the thickness of the rear end cylindrical portion 493 is the front end cylindrical portion 491. It is larger than the wall thickness. Therefore, in the pressurizing member 49, the intermediate tubular portion 492 is most difficult to bend, while the distal tubular portion 491 is most easily bent (functions as a spring). Here, in the present embodiment, the front end step portion 49b, the intermediate cylindrical portion 492, and the rear end step portion 49c function as an example of the protruding portion.

  In addition, the outer peripheral surfaces of the front-end stepped portion 49b, the intermediate cylindrical portion 492, and the rear-end stepped portion 49c of the pressure member 49 are coated with an insulating ceramic material containing alumina, zirconia, or the like. An insulating film 49a is continuously formed (see FIG. 4). Here, in the present embodiment, the insulating film 49a functions as an example of the insulating portion.

  The pressure member 49 is provided inside the distal end side casing 31 so that the distal end cylindrical portion 491 is on the distal end side. The pressure member 49 includes a piezoelectric element 41, a tip electrode member 42, a first rear end electrode member 43, a second rear end electrode member 44, an insulation ring 45, a tip side of the support member 50, an insulation pipe 60, a first One coil spring 46, the leading end side of the conductive member 47, and the leading end side of the holding member 48 are accommodated. The pressurizing member 49 is disposed on the rear end side of the diaphragm head 32 and on the front end side of the housing member 52. Further, the outer diameter of the pressure member 49 is different between the front end cylindrical portion 491, the intermediate cylindrical portion 492, and the rear end cylindrical portion 493, but is smaller than the inner diameter of the front end side casing 31 at all positions. Further, the inner diameter of the pressure member 49 is such that the tip electrode member 42 and the insulating pipe 60 (the piezoelectric element 41, the first rear end electrode member 43, the second rear end electrode member 44, and the insulating ring 45) face each other. The outer diameter of the support member 50 is slightly larger than the outer diameter of the support member 50 and is substantially the same as the outer diameter of the support member 50.

  Here, between the outer peripheral surface of the rear end cylindrical portion 493 provided on the rear end side of the pressing member 49 and the inner peripheral surface of the first front end side housing 311 on the rear end side, the butting pipe 57 Is arranged.

  Then, the surface on the distal end side (surface on the front side of the opening) of the distal end tubular portion 491 in the pressure member 49 is opposed to the concave portion 32c of the diaphragm head 32 through the air gap. On the other hand, the rear end side of the rear end tubular portion 493 is opposed to the first insulating member 61 through an air gap. In addition, the outer peripheral surface of the distal cylindrical portion 491 is opposed to the inner peripheral surface of the first distal end side housing 311 through an air gap. Further, the outer peripheral surfaces of the front end stepped portion 49b, the intermediate cylindrical portion 492, and the rear end stepped portion 49c are in contact with the insulating coating 49a and face the inner peripheral surface of the first front end side housing 311 through the insulating coating 49a. doing. Furthermore, the outer peripheral surface of the rear end tubular portion 493 is opposed to the inner peripheral surface of the abutment pipe 57 through an air gap. Thus, by providing the air gap and the insulating film 49a between the outer peripheral surface of the pressurizing member 49 and the inner peripheral surface of the first front end side housing 311 and the inner peripheral surface of the butting pipe 57, pressurization is performed. The member 49 is not in direct contact with the first front end side housing 311 and the butting pipe 57.

(Support member)
The support member 50 as an example of the second providing member is a member that exhibits a tubular shape as a whole. The support member 50 is made of a metal material such as stainless steel having conductivity and high heat resistance.

  The support member 50 is provided inside the front end side housing 31, and the front end side thereof is located inside the pressure member 49 and the rear end side thereof is located outside the pressure member 49. The support member 50 includes a rear end side (first convex portion 44b and second convex portion 44c) of the second rear end electrode member 44, a first coil spring 46, a distal end side of the conductive member 47, and a holding member. The front end side of 48 is accommodated. The support member 50 is disposed on the rear end side of the insulating ring 45 and on the front end side of the housing member 52. Further, the outer diameter of the support member 50 is substantially the same as the inner diameter of the first pressure member 37. Furthermore, although the inner diameter of the support member 50 varies depending on the position in the center line direction, the portion facing the second rear end electrode member 44 is larger than the outer diameter of the second rear end electrode member 44, and the first coil spring 46 The outer diameter of the first coil spring 46 is larger than the outer diameter of the first coil spring 46, the outer diameter of the conductive member 47 is larger than the outer diameter of the conductive member 47, and the outer diameter of the holding member 48 is larger than the outer diameter of the holding member 48. Bigger than. The front end surface of the support member 50 (the front surface of the opening) is in contact with the rear end surface of the insulating ring 45. On the other hand, the rear end surface of the support member 50 faces the housing member 52 through an air gap. Further, the front end side of the outer peripheral surface of the support member 50 is in contact with the inner peripheral surface of the pressure member 49, and the rear end side of the outer peripheral surface of the support member 50 is in contact with the front end side of the second coil spring 51. Yes. Here, the pressurizing member is obtained by the second welded portion 59 obtained by laser welding the inner peripheral surface on the rear end side of the pressurizing member 49 and the outer peripheral surface of the support member 50 facing this portion over the entire circumference. 49 and the support member 50 are joined and fixed. On the other hand, the inner peripheral surface of the support member 50 is opposed to the second rear end electrode member 44, the first coil spring 46, the conductive member 47, and the holding member 48 through the air gap. In this way, by providing an air gap between the inner peripheral surface of the support member 50 and the second rear end electrode member 44, the first coil spring 46, the conduction member 47, and the holding member 48, the support member 50, The second rear end electrode member 44, the first coil spring 46, the conduction member 47, and the holding member 48 are not in direct contact.

(Second coil spring)
The second coil spring 51 is a spiral member as a whole, and expands and contracts in the center line direction. The second coil spring 51 is made of a metal material such as stainless steel having electrical conductivity and high heat resistance, and its surface is plated with gold. Thus, in the present embodiment, the first coil spring 46 and the second coil spring 51 are made of different materials.

  The second coil spring 51 is provided inside the front end side housing 31, and the front end side is on the rear end side and the outer side of the support member 50, and the rear end side is on the front end side and the outer side of the housing member 52. positioned. That is, the second coil spring 51 is disposed across the support member 50 and the housing member 52. Further, the outer diameter of the second coil spring 51 is smaller than the inner diameter of the distal end side casing 31 (more specifically, the second distal end side casing 312). Further, the inner diameter of the second coil spring 51 is slightly smaller than the outer diameter on the rear end side of the support member 50 and the outer diameter on the front end side of the housing member 52. The outer periphery of the second coil spring 51 is opposed to the inner peripheral surface of the distal end side housing 31 through an air gap. Thus, by providing an air gap between the outer periphery of the second coil spring 51 and the inner peripheral surface of the front end side casing 31, the second coil spring 51 and the front end side casing 31 are not in direct contact with each other. .

(Housing member)
The housing member 52 is a member having a tubular shape as a whole. The housing member 52 is made of a metal material such as brass or stainless steel having conductivity and higher conductivity than the distal end side housing 31, and the surface thereof is plated with gold.

  FIG. 6 is a perspective view of the housing member 52. Below, the structure of the accommodating member 52 is demonstrated, also referring FIG. Also in FIG. 6, 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.

  The accommodation member 52 of the present embodiment is located on the most distal side and has a first cylindrical portion 521 provided with an opening at the distal end, and a second cylinder disposed on the rear end side of the first tubular portion 521. A cylindrical portion 522, a third cylindrical portion 523 disposed on the rear end side of the second cylindrical portion 522, and a fourth cylindrical portion 524 disposed on the rear end side of the third cylindrical portion 523. ing. In the housing member 52, the outer diameter increases in the order of the first tubular portion 521, the second tubular portion 522, the third tubular portion 523, and the fourth tubular portion 524. That is, in the housing member 52, the diameter increases stepwise (four steps) from the front end side toward the rear end side. The accommodating member 52 includes a first step portion 52a that connects the first cylindrical portion 521 and the second cylindrical portion 522, a second cylindrical portion 522, a third cylindrical portion 523, and the like. A second step portion 52b that connects the two at the boundary portion, and a third step portion 52c that connects the two at the boundary portion between the third tubular portion 523 and the fourth tubular portion 524. Note that, unlike the pressure member 49 described above, the accommodating member 52 is set to have a constant thickness regardless of the position in the center line direction. For this reason, in the pressurizing member 49, the inner diameter increases in the order of the first tubular portion 521, the second tubular portion 522, the third tubular portion 523, and the fourth tubular portion 524.

  The housing member 52 is provided so that the first cylindrical portion 521 is on the front end side across the inside of the front end side casing 31 and the rear end side casing 33. Inside the housing member 52, the rear end side of the conductive member 47, the rear end side of the holding member 48, the circuit board 53 and the ground plate 55 are housed. The housing member 52 is disposed on the rear end side of the support member 50 and on the front end side of the connection member 54. Further, the outer diameter of the housing member 52 is different between the first cylindrical portion 521, the second cylindrical portion 522, the third cylindrical portion 523, and the fourth cylindrical portion 524. 31 and smaller than the inner diameter of the rear end side housing 33. Further, the inner diameter of the housing member 52 is also different between the first tubular portion 521, the second tubular portion 522, the third tubular portion 523, and the fourth tubular portion 524. It is larger than the diameter.

  Here, the first insulating member 61 is disposed between the rear end side of the second cylindrical portion 522 and the second stepped portion 52 b in the housing member 52 and the inner peripheral surface of the second distal end side housing 312. ing. In addition, a second insulating member 62 is disposed between the rear end side of the third cylindrical portion 523 and the third stepped portion 52 c in the housing member 52 and the inner peripheral surface of the second distal end side housing 312. Yes. Further, the third insulating member 63 is disposed between the fourth cylindrical portion 524 and the first rear end side housing 331 in the housing member 52.

  And the surface at the front end side of the first tubular portion 521 in the housing member 52 (surface on the front side of the opening) faces the surface at the rear end side of the support member 50 through the air gap. The first tubular portion 521 is in contact with the second coil spring 51. On the other hand, the rear end side of the fourth cylindrical portion 524 faces the holding member 48. Further, the outer peripheral surfaces of the first cylindrical portion 521 and the first stepped portion 52a are opposed to the inner peripheral surface of the second distal end side housing 312 through the air gap. Furthermore, the outer peripheral surface of the second cylindrical portion 522 is opposed to the inner peripheral surface of the second distal end side housing 312 via the air gap and the first insulating member 61. Furthermore, the second stepped portion 52 b faces the inner peripheral surface of the second distal end side housing 312 via the first insulating member 61. Further, the outer peripheral surface of the third cylindrical portion 523 is opposed to the inner peripheral surface of the second distal end side housing 312 via the air gap and the second insulating member 62. Further, the outer peripheral surface of the third step portion 52 c is opposed to the inner peripheral surface of the second distal end side housing 312 via the second insulating member 62. The outer peripheral surface of the fourth cylindrical portion 524 faces the inner peripheral surface of the second front end side housing 312 via the air gap, and the first rear end via the air gap and the third insulating member 63. It faces the inner peripheral surface of the side housing 331. As described above, the air gap, the first insulating member 61, the second insulating member 62, and the third between the outer peripheral surface of the housing member 52 and the second front end side housing 312 and the first rear end side housing 331. By providing the insulating member 63, the housing member 52 is not in direct contact with the second front end side housing 312 and the first rear end side housing 331.

(Circuit board)
The circuit board 53 is a member having a rectangular plate shape as a whole. The circuit board 53 performs various processes using an electric circuit on an electric signal generated by a weak charge output from the piezoelectric element 41 in accordance with the received pressure, and is constituted by a so-called printed wiring board. The circuit board 53 is provided across the inside of the front end side casing 31 and the inside of the rear end side casing 33. The circuit board 53 is disposed on the rear end side of the conductive member 47 and on the front end side of the connection member 54. Further, the circuit board 53 is mounted on the holding member 48 and the entire circuit board 53 is disposed inside the housing member 52.

  The circuit board 53 includes an integration circuit that integrates an input signal (charge signal) input from the piezoelectric element 41 and converts it into a voltage signal, and an amplification that amplifies the voltage signal input from the integration circuit and outputs it as an output signal. A circuit and a power circuit serving as a power source for an operational amplifier or the like constituting the integrating circuit and the amplifying circuit are mounted (not shown).

(Connecting member)
The connection member 54 is a member having a columnar shape as a whole. The connecting member 54 includes a base material made of a synthetic resin material such as PPT having insulation properties, and wiring and terminals made of a metal material such as conductive copper. However, a portion (outer peripheral surface) of the connecting member 54 that contacts or faces the second rear end side housing 332 is made of a synthetic resin material so that the metal material is not exposed to this portion. . Further, the rear end side of the connection member 54 is provided with an opening having a recessed shape and opening toward the rear end side. A board-side connector 54 a that protrudes toward the tip side and is electrically connected to the circuit board 53 is provided on the tip side of the connection member 54. On the other hand, on the rear end side of the connection member 54, inside the opening, a cable side connector 54b that protrudes toward the rear end side and is a connection target of the connection cable 90 shown in FIG. It has been. In addition, a concave portion is provided on the outer peripheral surface on the distal end side of the connection member 54, and an O-ring 56 is attached to the concave portion.

  The connecting member 54 has a leading end side located inside the second rear end side housing 332 and a rear end side located outside the second rear end side housing 332. The O-ring 56 attached to the outer peripheral surface of the connection member 54 is in contact with the inner peripheral surface of the second rear end side casing 332 inside the second rear end side casing 332.

  The outer diameter of the cylindrical portion located on the front end side of the connection member 54 is smaller than the inner diameter of the second rear end side housing 332. On the other hand, the outer diameter of the cylindrical part located on the rear end side of the connection member 54 is substantially the same as the outer diameter of the second rear end side housing 332. The front end side of the connection member 54 is opposed to the inner peripheral surface of the second rear end side housing 332 through an air gap or an O-ring 56.

(Grounding plate)
The ground plate 55 is a member having a strip shape as a whole. The ground plate 55 is made of a conductive metal material such as phosphor bronze, and the surface thereof is plated with gold.

  The ground plate 55 is provided across the inside of the front end side housing 31 and the rear end side housing 33, and the front end is located inside the housing member 52 and above the circuit board 53. The rear end protrudes more toward the rear end than the rear end of the housing member 52. The front end side of the ground plate 55 is electrically connected to a ground terminal (not shown) of the circuit board 53, and the rear end side of the ground plate 55 is the inner periphery of the fourth cylindrical portion 524 in the housing member 52. Is electrically connected to the surface.

(O-ring)
The O-ring 56 is a member that exhibits an annular shape as a whole. The O-ring 56 is made of a synthetic resin material such as PTFE (Polytetrafluoroethylen) having insulating properties and high heat resistance, moisture permeability resistance, and acid resistance.

  The O-ring 56 is attached to the outer peripheral surface of the connection member 54, and when the connection member 54 is attached to the second rear end side housing 332, the outer peripheral surface of the connection member 54 and the second rear end side housing are attached. 332 is sandwiched between the inner peripheral surface of 332.

(Butting pipe)
The butting pipe 57 as an example of the fixing member is a member having a cylindrical shape as a whole. The abutting pipe 57 is made of a metal material such as stainless steel having conductivity and high heat resistance.

  The butting pipe 57 is disposed inside the region where the first tip side housing 311 and the second tip side housing 312 overlap in the tip side housing 31 and inside the first tip side housing 311. ing. The butting pipe 57 is located on the rear end side of the intermediate cylindrical portion 492 in the pressurizing member 49 and on the front end side of the first insulating member 61. Further, the outer diameter of the abutting pipe 57 is substantially the same as the inner diameter of the rear end side of the first front end side housing 311 that accommodates the abutting pipe 57. On the other hand, the inner diameter of the butting pipe 57 is larger than the outer diameter of the rear end cylindrical portion 493 in the pressurizing member 49. The surface on the front end side of the abutting pipe 57 is in contact with the rear end stepped portion 49c (formation surface of the insulating film 49a) of the pressure member 49. On the other hand, the rear end surface of the abutment pipe 57 faces the front end surface of the first insulating member 61 through an air gap. Further, the outer peripheral surface of the butting pipe 57 is in contact with the inner peripheral surface on the rear end side in the first front end side housing 311. Here, the first welded portion 58 obtained by laser welding the inner peripheral surface of the rear end side of the first front end side housing 311 and the outer peripheral surface of the butting pipe 57 facing this portion over the entire circumference. 1 The front end side housing 311 and the butting pipe 57 are joined and fixed. On the other hand, the inner peripheral surface of the abutting pipe 57 is opposed to the outer peripheral surface of the rear end cylindrical portion 493 in the pressurizing member 49 through the air gap. Thus, by providing the insulating coating 49a and the air gap between the rear end stepped portion 49c and the rear end cylindrical portion 493 of the pressurizing member 49 and the abutting pipe 57, the abutting pipe 57 and the pressurizing member 57 are pressurized. It does not contact the member 49 directly.

(First weld)
The first welded portion 58 is a part formed by laser welding the inner peripheral surface on the rear end side of the first front end side housing 311 and the outer peripheral surface of the butting pipe 57 over the entire circumference.

(Second weld)
The second welded portion 59 is a portion formed by laser welding the inner peripheral surface on the rear end side of the pressing member 49 and the outer peripheral surface of the support member 50 over the entire circumference.

(Insulated pipe)
The insulating pipe 60 is a member having a cylindrical shape as a whole. The insulating pipe 60 is made of a synthetic resin material such as LCP (Liquid Crystal Polymer) having insulating properties. The insulating pipe 60 is disposed inside a pressurizing member 49 provided inside the distal end side housing 31. Inside the insulating pipe 60, the front end side of the main body 44a of the piezoelectric element 41, the first rear end electrode member 43, and the second rear end electrode member 44 is accommodated. The insulating pipe 60 is located on the rear end side of the front end electrode member 42 and on the front end side of the insulating ring 45. Further, the outer diameter of the insulating pipe 60 is slightly smaller than the inner diameter of the pressure member 49. Furthermore, the inner diameter of the insulating pipe 60 is slightly larger than the outer diameter of each of the main body portions 44a of the piezoelectric element 41, the first rear end electrode member 43, and the second rear end electrode member 44. The front end side of the insulating pipe 60 faces the rear end surface of the front end electrode member 42. On the other hand, the rear end side of the insulating pipe 60 faces the front end surface of the insulating ring 45. Further, the outer peripheral surface of the insulating pipe 60 is opposed to the inner peripheral surface of the pressurizing member 49. Furthermore, the inner peripheral surface of the insulating pipe 60 is opposed to the outer peripheral surface of the main body 44 a in the piezoelectric element 41, the first rear end electrode member 43, and the second rear end electrode member 44. Thus, the air gap by the insulating pipe 60 and the insulating pipe 60 is provided between the pressure member 49 and the main body 44a of the piezoelectric element 41, the first rear end electrode member 43, and the second rear end electrode member 44. Thus, the pressing member 49 is not in direct contact with the first rear end electrode member 43 and the second rear end electrode member 44.

(First insulation member)
The first insulating member 61 is a member having a cylindrical shape on the front end side and an annular shape on the rear end side. The first insulating member 61 is made of a ceramic material such as alumina that has insulating properties and high heat resistance.

  The first insulating member 61 is disposed inside the distal end side casing 31. And the 1st insulating member 61 is arrange | positioned in the outer side of the 2nd cylindrical part 522 in the accommodating member 52, and the 2nd level | step-difference part 52b (refer FIG. 6). Further, the outer diameter of the first insulating member 61 is slightly smaller than the inner diameter of the second tip side housing 312 at the corresponding part, and the inner diameter of the first insulating member 61 is smaller than the outer diameter of the accommodating member 52 at the corresponding part. Is also slightly larger. The outer peripheral surface of the first insulating member 61 is in contact with the second distal end side housing 312, and the inner peripheral surface of the first insulating member 61 is in contact with the housing member 52.

(Second insulation member)
The second insulating member 62 is a member having an annular shape as a whole. The second insulating member 62 is made of a ceramic material such as alumina that has insulating properties and high heat resistance.

  The second insulating member 62 is disposed inside the front end side casing 31 and at a position on the rear end side with respect to the first insulating member 61. The second insulating member 62 is disposed outside the third cylindrical portion 523 and the third stepped portion 52c (see FIG. 6) in the housing member 52. Further, the outer diameter of the second insulating member 62 is slightly smaller than the inner diameter of the second tip side housing 312 at the corresponding portion, and the inner diameter of the second insulating member 62 is smaller than the outer diameter of the accommodating member 52 at the corresponding portion. Is also slightly larger. The outer peripheral surface of the second insulating member 62 is in contact with the second distal end side housing 312, and the inner peripheral surface of the second insulating member 62 is in contact with the housing member 52.

  Thus, by providing the air gap, the first insulating member 61, and the second insulating member 62 between the distal end side casing 31 (second distal end side casing 312) and the housing member 52, the distal end side casing is provided. 31 and the accommodation member 52 do not contact directly.

(Third insulating member)
The third insulating member 63 is a member having a tubular shape as a whole. The third insulating member 63 is made of a ceramic material such as alumina that has insulating properties and high heat resistance.

  The third insulating member 63 is disposed inside the rear end side housing 33 and at a position closer to the rear end side than the second insulating member 62. The third insulating member 63 is located outside the fourth tubular portion 524 in the housing member 52. Further, the outer diameter of the third insulating member 63 is substantially the same as the inner diameter of the first rear end side housing 331, and the inner diameter of the third insulating member 63 is the outer diameter of the fourth tubular portion 524 in the housing member 52. Bigger than. The outer peripheral surface of the third insulating member 63 is in contact with the inner peripheral surface of the first rear end side housing 331, and the inner peripheral surface of the third insulating member 63 is partially accommodated on the front end side. Others face the accommodating member 52 through the air gap.

[Configuration of seal part]
The seal portion 70 includes a first seal member 71 that is positioned relatively on the front end side and a second seal member 72 that is positioned relatively on the rear end side. In the state where the pressure detection device 20 is attached to the internal combustion engine 10, the first seal member 71 and the second seal member 72 abut against the inner peripheral surface of the communication hole 13 a (see FIG. 1) provided in the cylinder head 13. .

(First seal member)
The first seal member 71 is a member having a hollow structure and exhibiting a tubular shape as a whole. The first seal member 71 is made of a synthetic resin material such as PTFE having insulating properties and high heat resistance and acid resistance.

  The first seal member 71 is fitted in a recess 311 a provided on the outer peripheral surface of the first distal end side housing 311. The inner diameter is slightly smaller than the outer diameter of the recess 311a, and the outer diameter is slightly larger than the inner diameter of the communication hole 13a.

(Second seal member)
The second seal member 72 is a member having an annular shape as a whole, and an O-ring is used here. The second seal member 72 is also made of a synthetic resin material such as PTFE having insulating properties and high heat resistance and acid resistance.

  The second seal member 72 is fitted in a recess 312 a provided on the outer peripheral surface of the second distal end side housing 312. The inner diameter is slightly smaller than the outer diameter of the recess 312a, and the outer diameter is slightly larger than the inner diameter of the communication hole 13a.

[Electrical connection structure in pressure detector]
Here, an electrical connection structure in the pressure detection device 20 will be described.

(Positive path)
In the pressure detection device 20, the end face (positive electrode) on the rear end side of the piezoelectric element 41 has a metal first rear end electrode member 43, a metal second rear end electrode member 44, and a metal first coil spring. 46 and the metal conductive member 47 is electrically connected. The metal conductive member 47 is electrically connected to an input terminal (not shown) provided on the circuit board 53 via a metal holding portion, a wiring, and a terminal provided on the holding member 48. The In the following, the circuit board 53 is connected to the circuit board 53 through the first rear end electrode member 43, the second rear end electrode member 44, the first coil spring 46, the conductive member 47, and the holding member 48 from the rear end side surface of the piezoelectric element 41. The electrical path to reach is called the “positive path”.

(Negative path)
On the other hand, in the pressure detection device 20, the end face (negative electrode) on the tip side of the piezoelectric element 41 has a metal tip electrode member 42, a metal pressure member 49, and a metal support member 50 (second welded portion). 59), a metal second coil spring 51, a metal housing member 52, and a metal ground plate 55, and electrically connected to a ground terminal (not shown) provided on the circuit board 53. It is connected. In the following, the electrical connection from the surface on the front end side of the piezoelectric element 41 to the circuit board 53 via the front end electrode member 42, the pressure member 49, the support member 50, the second coil spring 51, the housing member 52 and the ground plate 55 This path is called “negative path”.

(Case path)
On the other hand, in the pressure detection device 20, the metal diaphragm head 32 is connected to the metal rear end via the metal front end side casing 31 (the first front end side casing 311 and the second front end side casing 312). The side housing 33 (the first rear end side housing 331 and the second rear end side housing 332) is electrically connected. Moreover, in this pressure detection apparatus 20, the metal 1st front end side housing | casing 311 is electrically connected with the metal butting pipe | tube 57 (1st welding part 58). Hereinafter, an electrical path from the diaphragm head 32 through the front end side casing 31 to the rear end side casing 33 and the butting pipe 57 is referred to as a “housing path”.

(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 accommodated inside the negative path. The positive path and the negative path are electrically insulated by the insulating pipe 60, the insulating ring 45, the holding member 48, and an air gap formed between the two paths. Here, in the present embodiment, the negative path is an example of the first electrical path, and the positive path is an example of the second electrical path.

(Relationship between negative path and chassis path)
Moreover, in this pressure detection apparatus 20, the housing | casing path | route exists in the outer side of a negative path | route. In other words, the negative path is accommodated inside the housing path. The negative path and the casing path are the insulating film 42a provided on the tip electrode member 42, the insulating film 49a provided on the pressure member 49, the first insulating member 61, the second insulating member 62, and the third. It is electrically insulated by the insulating member 63 and an air gap formed between both paths.

(Relationship between chassis path and positive path)
In the pressure detection device 20, as a result, the housing path exists outside the positive path. In other words, the positive path is accommodated inside the housing path. As described above, the positive path and the negative path are electrically insulated from each other, and the negative path and the casing path are electrically insulated from each other. Are electrically insulated.

(Other)
Here, the casing 30 constituting the casing path is a part exposed to the outside in the pressure detection device 20, and in particular, the diaphragm head 32 faces the combustion chamber C where the acidity increases with combustion. It is a part. On the other hand, each member constituting the positive path and the negative path is a part that is accommodated in the casing 30 in the pressure detection device 20. For this reason, it is preferable that each member constituting the positive path and the negative path is made of a material having higher conductivity than each member constituting the housing path (housing part 30). Each member constituting the housing portion 30) is preferably made of a material having higher acid resistance than each member constituting the positive path and the negative path.

[Assembly procedure of pressure detector]
Next, an assembly procedure of the pressure detection device 20 used in the present embodiment will be described.

  First, the front end side of the first front end side housing 311 and the back surface side (projection 32d side) of the diaphragm head 32 are opposed to each other and abut against each other. In this state, laser welding is performed over the entire circumference at the boundary between the first front end side housing 311 and the diaphragm head 32.

  Next, the pressure member 49 is inserted into the first front end side housing 311 in the structure including the first front end side housing 311 and the diaphragm head 32 from the rear end side with the front end cylindrical portion 491 as the front end side. To do. At this time, the pressure member 49 is inserted until the tip step portion 49 b provided on the outer peripheral surface of the pressure member 49 hits the inner step portion 311 b provided on the inner peripheral surface of the first tip side housing 311. Do. Along with this, the insulating step 49 a provided on the outer peripheral surface of the front end stepped portion 49 b and the intermediate cylindrical portion 492 of the pressure member 49 comes into contact with the inner peripheral surface of the first front end side housing 311. Further, the convex portion 32 d of the diaphragm head 32 is inserted into an opening portion provided on the distal end side of the distal end tubular portion 491 in the pressing member 49.

  Subsequently, the butting pipe 57 is inserted from the rear end side between the inner peripheral surface of the first front end side housing 311 and the outer peripheral surface of the rear end cylindrical portion 493 in the pressing member 49. At this time, the abutting pipe 57 is inserted until the front end side of the abutting pipe 57 abuts against the rear end stepped portion 49 c provided in the pressing member 49. Along with this, the insulating film 49 a provided on the rear end step portion 49 c of the pressing member 49 comes into contact with the front end side of the butting pipe 57.

  In this state, the rear end side of the first front end side housing 311 and the butting pipe 57 are laser welded over the entire circumference to form the first welded portion 58. At this time, when the intermediate cylindrical portion 492 of the pressure member 49 is sandwiched between the inner stepped portion 311b of the first front end side housing 311 and the front end side of the butting pipe 57, the pressure member 49 is It is fixed to the first distal end side housing 311. As a result, the pressure member 49 is positioned with respect to the first front end side housing 311 and the diaphragm head 32.

  Next, in the pressurizing member 49 in the structure including the first front end side housing 311, the diaphragm head 32, the pressurizing member 49 and the butting pipe 57, the front end electrode member 42, the insulating pipe 60, The piezoelectric element 41, the first rear end electrode member 43, the second rear end electrode member 44, the insulating ring 45, and the support member 50 are inserted in this order. When the tip electrode member 42 is inserted into the pressure member 49, the surface on which the insulating film 42a is formed is the tip side. Further, when the second rear end electrode member 44 is inserted into the pressure member 49, the main body portion 44a is the front end side, and the second convex portion 44c is the rear end side. At this time, the insulating film 42 a provided on the tip end side of the tip electrode member 42 accommodated in the pressurizing member 49 contacts the convex portion 32 d provided on the rear end side of the diaphragm head 32. Further, the distal end side of the main body 44 a of the piezoelectric element 41, the first rear end electrode member 43, and the second rear end electrode member 44 is disposed inside the insulating pipe 60. Further, the first convex portion 44 b and the second convex portion 44 c of the second rear end electrode member 44 are exposed to the inside of the front end side of the support member 50 through holes provided in the insulating ring 45.

  In this state, the position of the support member 50 in the center line direction is adjusted with respect to the pressure member 49, and the load (preload) applied to the piezoelectric element 41 via the pressure member 49 and the support member 50 is adjusted.

  Then, after the position adjustment of the support member 50 in the center line direction with respect to the pressure member 49 is completed, the rear end side of the pressure member 49 and the support member 50 are laser-welded over the entire circumference to form the second welded portion 59. To do. At this time, the piezoelectric element 41 has a distal end side through a front electrode member 42 and a rear end side through a first rear end electrode member 43, a second rear end electrode member 44, an insulating ring 45, and a support member 50. It is fixed to the pressure member 49. In this state, the pressurizing member 49 is already fixed to the first front end side housing 311 and the diaphragm head 32. For this reason, the piezoelectric element 41 accommodated in the pressure member 49 is fixed to the diaphragm head 32 in a state where a predetermined preload is applied. As a result, the pressure member 49, the support member 50, and the piezoelectric element 41 are positioned with respect to the first distal end side housing 311 and the diaphragm head 32.

  Subsequently, the first coil spring 46 is inserted from the rear end side into the support member 50 in the structure to which the support member 50 is attached, and the second rear end electrode member is exposed inside the front end side of the support member 50. The second convex portion 44c of 44 is attached. Further, the second coil spring 51 is inserted and attached to the rear end side of the support member 50 in the structure from the rear end side. Further, the second front end side housing 312 is screwed and attached to the first front end side housing 311 in the structure from the rear end side. Furthermore, the first insulating member 61 and the second insulating member 62 are inserted into the second front end side housing 312 from the rear end side in this order. Accordingly, the first insulating member 61 is positioned by abutting against a step portion provided on the distal end side in the second distal end side housing 312, and the second insulating member 62 is positioned in the second distal end side housing 312. It is positioned by abutting against a step provided on the rear end side.

  On the other hand, the conductive member 47 is inserted from the distal end side into the distal end side of the holding member 48 in a separate process from the assembly of the structure. Further, the circuit board 53 including the ground plate 55 is attached to the rear end side of the holding member 48. At this time, the rear end convex part 47b of the conductive member 47 attached to the holding member 48 and the circuit board 53 are electrically connected. Then, the holding member 48 on which the conductive member 47 and the circuit board 53 (the ground plate 55) are mounted is inserted into the housing member 52 from the rear end side with the conductive member 47 as the front end side. At this time, the holding member until the boundary between the cylindrical portion and the plate-like portion in the holding member 48 (the front end side of the plate-like portion) abuts against the inner peripheral surface of the second stepped portion 52 b provided in the housing member 52. Insert 48. Accordingly, the distal end side of the cylindrical portion of the holding member 48 and the distal end side of the conductive member 47 exposed from the cylindrical portion of the holding member 48 (the distal end side recess 47a) are closer to the distal end side than the first cylindrical portion 521. Protruding. Further, the inner peripheral surface of the housing member 52 and the rear end side of the ground plate 55 are in contact with each other.

  The housing member including the conductive member 47, the circuit board 53 (the ground plate 55) and the holding member 48 from the rear end side in the second front end side housing 312 in the structure to which the second insulating member 62 is attached. 52 is inserted with the first cylindrical portion 521 as the distal end side. At this time, until the second stepped portion 52b provided in the housing member 52 hits the first insulating member 61 attached in the second distal end side housing 312 (the third stepped portion 52c provided in the housing member 52). Until the second insulating member 62 attached in the second distal end side housing 312 hits). Accordingly, the rear end side of the second cylindrical portion 522 and the outer peripheral surface of the second stepped portion 52 b in the housing member 52 are in contact with the inner peripheral surface and the rear end surface of the first insulating member 61. Further, the rear end side of the third cylindrical portion 523 and the outer peripheral surface of the third stepped portion 52 c in the housing member 52 are in contact with the inner peripheral surface and the rear end side surface of the second insulating member 62. On the other hand, the rear end side of the first coil spring 46 is inserted into the front end side concave portion 47a of the conductive member 47, and the rear end of the first coil spring 46 hits the bottom portion of the front end side concave portion 47a. Further, the first cylindrical portion 521 of the housing member 52 is inserted into the rear end side of the second coil spring 51, and the rear end of the second coil spring 51 abuts against the first stepped portion 52 a of the housing member 52. As a result, the first coil spring 46 and the second coil spring 51 are compressed in the direction of the center line as compared to before the housing member 52 is inserted into the structure.

  Subsequently, the first rear end side housing 331 and the third insulating member 63 are inserted and attached from the rear end side to the second front end side housing 312 in the structure to which the accommodation member 52 is attached. As a result, the outer peripheral surface of the fourth cylindrical portion 524 in the housing member 52 comes into contact with the inner peripheral surface of the third insulating member 63. Further, the second rear end side casing 332 is inserted into the first rear end side casing 331 from the rear end side.

  Then, with respect to the second rear end side casing 332 in the structure to which the second rear end side casing 332 is attached, the connection member 54 with the O-ring 56 mounted on the outer peripheral surface is connected from the rear end side to the board side. The connector 54a is inserted with the tip side. At this time, the O-ring 56 attached to the connection member 54 enters the second rear end side housing 332 and contacts the second rear end side housing 332. Further, the circuit board 53 and the board-side connector 54 a provided on the connection member 54 are electrically connected.

Finally, the first seal member 71 is attached to the recess 311a of the first tip side housing 311 in the structure to which the connection member 54 is attached, and the second seal is attached to the recess 312a of the second tip side housing 312. The member 72 is attached.
Thus, the assembly of the pressure detection device 20 is completed.

[Pressure detection operation by pressure detector]
Now, 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 32 a of the diaphragm head 32. In the diaphragm head 32, the pressure received by the pressure receiving surface 32a is transmitted to the convex portion 32d on the back side, and further transmitted from the convex portion 32d to the tip electrode member 42 via the insulating film 42a. Then, the pressure transmitted to the tip electrode member 42 acts on the piezoelectric element 41 sandwiched between the tip electrode member 42 and the first rear end electrode member 43, and the piezoelectric element 41 has a charge corresponding to the received pressure. Arise. The charge generated in the piezoelectric element 41 is supplied as an input signal terminal (not shown) charge signal of the circuit board 53 through a positive path. The charge signal supplied to the circuit board 53 is converted into an output signal by performing various processes in a circuit mounted on the circuit board 53. Then, the output signal output from the circuit board 53 is transmitted to the outside (here, the connection cable 90 and the control device 80) via the connection member 54.

[Effects of the present embodiment]
In the pressure detection device 20 of the present embodiment, the piezoelectric element 41 is sandwiched between the pressure member 49 and the support member 50 by fixing the positional relationship between the pressure member 49 and the support member 50 in the center line direction. A predetermined load is applied to the piezoelectric element 41. Then, in a state where the pressure member 49 that accommodates the piezoelectric element 41 is in contact with the inner peripheral surface of the distal end side casing 31 via the insulating film 49a, the distal end side casing is used by using the abutment pipe 57. The pressurizing member 49 is fixed to 31. As a result, the pressure member 49 and the front end side casing 31 are electrically insulated from each other, and a load fluctuation is applied to the casing unit 30 (the front end side casing 31) via the pressure member 49 and the support member 50. The piezoelectric element 41 can be fixed in a suppressed state.

  Further, in the pressure detection device 20 of the present embodiment, the insulating film 42 a is provided on the distal end side of the distal electrode member 42 existing between the piezoelectric element 41 and the diaphragm head 32. Thereby, the tip electrode member 42 and the diaphragm head 32 can be electrically insulated.

  Here, in the present embodiment, the tip electrode member 42 and the pressure member 49 described above also serve as a negative path of the piezoelectric element 41. By adopting the above-described configuration, this negative electrode is used. The path can be electrically insulated from the casing path including the distal end side casing 31 and the diaphragm head 32.

  The pressure detection device 20 of the present embodiment is attached to an internal combustion engine 10, and when the internal combustion engine 10 is mounted on an automobile, noise having a frequency on the order of kHz (hereinafter referred to as “kHz”) generated by a horn, a headlight, a wiper, or the like. Is referred to as low-frequency noise) enters the cylinder head 13 of the internal combustion engine 10. And in this Embodiment, since the housing | casing part 30 comprised with the metal among the pressure detection apparatuses 20 is attached to the cylinder head 13 comprised with the metal, the low frequency noise which penetrate | invaded the cylinder head 13 is It propagates also to the housing part 30 of the pressure detection device 20.

  Here, in the pressure detection device 20 of the present embodiment, the casing path including the casing section 30 is electrically insulated from the positive path and the negative path from the piezoelectric element 41 to the circuit board 53. Yes. For this reason, the low-frequency noise propagated from the cylinder head 13 to the casing 30 of the pressure detection device 20 is not easily transmitted to the circuit board 53 via the pressurizing member 49, the support member 50, the conductive member 47, and the like. As a result, the fluctuation (fluctuation) of the potential in the circuit board 53 due to the low frequency noise is suppressed, and the fluctuation (fluctuation) of the output signal output from the circuit board 53 to the outside (such as the control device 80). Can be reduced.

  When the internal combustion engine 10 is mounted on an automobile, radio waves having a frequency on the order of MHz, which are usually used in mobile phones, radios, televisions, and the like, fly around the automobile. When this radio wave is applied to the conductive member 47 provided in the pressure detection device 20, noise having a frequency on the order of MHz (hereinafter referred to as high frequency noise) is transmitted to the circuit board 53.

  Here, in the pressure detection device 20 of the present embodiment, the pressure member 49 and the support member 50 are used to cover the conductive member 47. For this reason, the radio wave applied to the pressure detection device 20 from the outside is blocked by the pressure member 49 and the support member 50, and is not easily transmitted to the conductive member 47. As a result, the fluctuation (fluctuation) of the potential in the circuit board 53 due to the high frequency noise is suppressed, and the fluctuation (fluctuation) of the output signal output from the circuit board 53 to the outside can be reduced. Become.

  In the present embodiment, the circuit board 53 is covered with a metal housing member 52. For this reason, the radio wave applied to the pressure detection device 20 from the outside is blocked by the housing member 52, and is difficult to reach the circuit board 53. As a result, the fluctuation (fluctuation) of the potential in the circuit board 53 due to the high frequency noise is suppressed, and the fluctuation (fluctuation) of the output signal output from the circuit board 53 to the outside can be further reduced. It becomes possible.

[Others]
In the present embodiment, the insulating film 42a is provided on the tip side of the tip electrode member 42 to electrically insulate the tip electrode member 42 constituting the negative path from the diaphragm head 32 constituting the casing path. However, it is not limited to this. For example, an insulating plate made of a ceramic material such as alumina having insulating properties and high heat resistance may be disposed between the tip electrode member 42 and the diaphragm head 32.

  In the present embodiment, a negative path is configured by providing an insulating film 49a on a part of the outer peripheral surface of the pressure member 49 (intermediate cylindrical portion 492, front end step portion 49b, and rear end step portion 49c). The pressurizing member 49 to be electrically insulated from the first distal end side housing 311 and the butting pipe 57 constituting the housing path is not limited to this. For example, an insulating ring made of a ceramic material such as alumina that has insulating properties and high heat resistance is disposed between the pressure member 49 and the first distal end side housing 311 and the abutting pipe 57, or an air gap is provided. It does not matter if they are formed.

  In the present embodiment, the rear end side of the second cylindrical portion 522 in the housing member 52 and the second stepped portion 52b and the inner peripheral surface of the second distal end side housing 312 are provided in the third in the housing member 52. Between the rear end side of the cylindrical portion 523 and the third stepped portion 52 c and the inner peripheral surface of the second front end side housing 312, the fourth cylindrical portion 524 and the first rear end side housing 331 of the housing member 52 The first insulating member 61, the second insulating member 62, and the third insulating member 63 are arranged between the housing member 52 that forms the negative path and the front end side casing that forms the housing path, respectively. 31 and the rear end side housing 33 are electrically insulated, but the present invention is not limited to this. For example, a part of the outer peripheral surface of the housing member 52 is formed with an insulating film formed by coating an insulating ceramic material containing alumina, zirconia, or the like, or the housing member 52 and the front end housing 31, the rear end side An air gap may be formed between the housing 33 and the housing 33.

  Further, in the present embodiment, the first distal end side housing 311 and the butting pipe 57 are fixed using the first welded portion 58. However, the present invention is not limited to this. It may be fixed by. Furthermore, in the present embodiment, the pressure member 49 and the support member 50 are fixed using the second welded portion 59, but the present invention is not limited to this. For example, both are fixed by screwing or the like. It doesn't matter if you do.

  In the present embodiment, the first rear end electrode member 43 and the second rear end electrode member 44 are arranged as separate members. However, the present invention is not limited to this, for example, the first rear end electrode member. 43 and the second rear end electrode member 44 may be replaced with one member.

  Furthermore, in the present embodiment, the tip electrode member 42 is not accommodated in the insulating pipe 60. However, the present invention is not limited to this, and the tip electrode member 42 may be accommodated in the insulating pipe 60. It doesn't matter.

  Furthermore, in the present embodiment, the case where the piezoelectric element 41 is used as the pressure detection element in the pressure detection device 20 has been described as an example. However, the present invention is not limited to this example. An electrode or the like may be used.

DESCRIPTION OF SYMBOLS 1 ... Pressure detection system, 10 ... Internal combustion engine, 20 ... Pressure detection apparatus, 30 ... Case part, 31 ... Front end side case, 32 ... Diaphragm head, 33 ... Rear end side case, 40 ... Detection mechanism part, 41 DESCRIPTION OF SYMBOLS ... Piezoelectric element, 42 ... Lead electrode member, 42a ... Insulating film, 43 ... First rear end electrode member, 44 ... Second rear end electrode member, 45 ... Insulating ring, 46 ... First coil spring, 47 ... Conductive member, 48 DESCRIPTION OF SYMBOLS ... Holding member 49 ... Pressure member 49a ... Insulating film 50 ... Support member 51 ... Second coil spring 52 ... Housing member 53 ... Circuit board 54 ... Connection member 55 ... Grounding plate 56 ... O-ring 57 ... Butting pipe, 58 ... First weld, 59 ... Second weld, 60 ... Insulation pipe, 61 ... First insulation member, 62 ... Second insulation member, 63 ... Third insulation member, 70 ... Seal 71, first seal member, 72 ... second seal Wood, 80 ... controller, 90 ... connecting cable

Claims (5)

A cylindrical housing;
A detection element that is housed inside the housing and detects a change in pressure from the front end side to the rear end side of the housing;
An application member that houses the detection element and is housed in the housing, and sandwiches the detection element from the front end side and the rear end side, thereby applying a load to the detection element;
A deformable member attached to the distal end side of the housing and deformed by receiving pressure from the outside;
An insulating transmission part that is insulative and provided between the deformation member and the detection element inside the housing, and transmits pressure acting on the deformation member to the detection element;
An insulating part that is insulative and is provided in contact with the casing and the application member inside the casing;
A pressure detection device comprising: a fixing member that fixes the application member to the housing in a state of being electrically insulated from the deformation member and the housing. The application member has a cylindrical shape and includes a protruding portion protruding outward on the outer peripheral surface,
The said fixing member fixes the said provision member to the said housing | casing by pinching | interposing the said protrusion part between the internal peripheral surfaces of the said housing | casing via the said insulation part. Pressure detection device. The imparting member is
A first application that is arranged outside the detection element, is electrically connected to the front end side of the detection element and is electrically insulated from the rear end side of the detection element, and applies a load from the front end side of the detection element A member,
Provided on the rear end side of the first application member, electrically connected to the first application member, electrically insulated from the detection element, and fixed to the first application member, thereby fixing the detection element. The pressure detecting device according to claim 1, further comprising a second applying member that applies a load from the rear end side. A conductive member that conducts a detection signal output from the detection element by being electrically connected to a rear end side of the detection element and housed in the application member;
The said providing member becomes the ground of the said detection element by being electrically connected with the front end side of the said detection element, and being electrically insulated with the said conduction member, The said detection element is characterized by the above-mentioned. The pressure detection apparatus of any one of Claims. A cylindrical housing;
A deformation member attached to the front end side of the housing, electrically connected to the housing, and deformed by receiving pressure from the outside;
A detection element that is provided inside the housing and on the rear end side of the deformable member and detects pressure acting via the deformable member;
Provided between the deformation member and the detection element inside the casing, electrically connected to the detection element, electrically insulated from the deformation member, and acting via the deformation member A first transmission member that transmits pressure to the detection element and constitutes a first electrical path of the detection element;
It is provided inside the housing and on the rear end side of the detection element, is electrically connected to the detection element and is electrically insulated from the first transmission member, and passes through the second electric path of the detection element. A second transmission member comprising;
An interior of the housing is provided to receive the detection element, the first transmission member, and the second transmission member, and is electrically connected to the first transmission member and electrically connected to the second transmission member. And an applying member that applies a load to the detection element via the first transmission member and the second transmission member and constitutes the first electric path;
A pressure detection device including: a fixing member that fixes the application member to the casing in a state of being electrically insulated from the deformation member and the casing.

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