JP2020085624A - Pressure detector, circuit built-in member, and manufacturing method for pressure detector - Google Patents

Abstract

To increase the reliability of electrical connection between a piezoelectric element and a processing circuit.SOLUTION: A circuit built-in member 57 provided in a pressure detector that detects the combustion pressure, etc., of an internal combustion engine, comprises: a processing circuit for applying a process to the electric signal outputted by a piezoelectric element; a seal unit 92 for sealing the processing circuit and having an insulating property; and an input ground plate 94 having electrical conductivity and connected at one end to the processing circuit and exposed at other end to the side face of a medium-diameter unit 922 of the seal unit 92. When this circuit built-in member 57 is pushed into the inside of a second accommodation member having electrical conductivity and presenting a cylindrical shape, a body unit 943 provided in the input ground plate 94 is bumped against the inner circumferential face of the second accommodation member.SELECTED DRAWING: Figure 7

Description

The present invention relates to a pressure detection device, a circuit built-in member, and a method for manufacturing the pressure detection device.

For example, in a device such as an automobile having an internal combustion engine, a plurality of detection devices for detecting pressure, temperature and the like are mounted in the device. Then, based on the detection results of these detection devices, a control device called an ECU (Engine Control Unit) controls the operation of the internal combustion engine.

Patent Document 1 discloses a piezoelectric element that detects a change in pressure, a circuit board that is connected to the positive electrode side of the piezoelectric element and that is provided with a processing circuit that processes an output signal of the piezoelectric element, and has conductivity. A housing member that is arranged so as to cover the circuit board, is connected to the negative electrode side of the piezoelectric element, and is connected to the ground of the processing circuit via a ground plate provided on the circuit board side, the piezoelectric element, the circuit board, and There is described a pressure detection device that accommodates a housing member therein, and includes a detection element, a circuit board, and a housing that is electrically insulated from the housing member.

JP, 2017-173122, A

Here, in the case of adopting a configuration in which the housing member and the ground plate provided on the circuit board side are simply brought into contact with each other, for example, when an impact is applied to the pressure detection device from the outside, the ground plate and the housing member Might be separated from each other, and the electrical path might be cut off.
An object of the present invention is to improve reliability of electrical connection between a piezoelectric element and a processing circuit.

The pressure detection device of the present invention includes a piezoelectric element that outputs an electric signal according to the pressure received from the outside, a conductive member, a housing member to which one end of the piezoelectric element is connected, and the other end of the piezoelectric element. A processing circuit that is connected to the processing circuit and that processes the electric signal; a sealing portion that has an insulating property and seals the processing circuit; and a conductive and one is connected to the processing circuit and the other. Includes a conductive portion exposed to the outside of the side surface of the sealing portion, and the conductive portion includes a circuit built-in member that abuts the accommodation member by being accommodated in the accommodation member.
In such a pressure detection device, the conductive portion in the circuit-embedded member may be formed of a leaf spring having a restoring force from the side surface of the sealing portion toward the housing member.
Further, the sealing portion in the circuit-embedded member may be provided behind the conductive portion, and may have a protrusion protruding from the side surface of the sealing portion toward the housing member.
The sealing portion of the circuit-embedded member may further include another protrusion provided on the back side of the protrusion of the sealing portion and protruding from the side surface of the sealing portion toward the housing member. It can be a feature.
Further, the accommodating member is provided with a hole penetrating an inner surface and an outer surface of the accommodating member, and the conductive portion provided in the circuit built-in member is arranged at a portion where the hole is formed to form the hole. It can be characterized in that the accommodating member and the conductive portion are joined at a site.
Further, the piezoelectric element is accommodated inside the accommodating member, has conductivity and is accommodated inside the accommodating member, and is connected to the piezoelectric element and the processing circuit, thereby applying the electric signal to the piezoelectric element. It further comprises a conductive member that conducts to the processing circuit, wherein one pole side of the piezoelectric element is connected to the conductive member, and the other pole side of the piezoelectric element is connected to the containing member. can do.
Further, it may be characterized in that the housing member is further provided with a housing portion that houses the housing member therein and is electrically insulated from the housing member.
From another point of view, the circuit built-in member of the present invention is a processing circuit to which one end of a piezoelectric element that outputs an electric signal according to the pressure received from the outside is connected and which processes the electric signal. A sealing portion that has an insulating property and seals the processing circuit; and a conductive portion that has conductivity and one of which is connected to the processing circuit and the other of which is exposed on a side surface of the sealing portion. is doing.
From another point of view, a method of manufacturing a pressure detecting device according to the present invention includes a processing circuit that processes an electric signal supplied from one pole side of a piezoelectric element, and a processing circuit that has insulation properties and is related to the processing circuit. A circuit built-in member having an encapsulating part for encapsulating and a conductive part, one of which is connected to the processing circuit and the other of which is exposed outside the side surface of the encapsulating part. And a step of accommodating the circuit built-in member with respect to an accommodating member having conductivity and connected to the other pole side of the piezoelectric element.
In the manufacturing method of such a pressure detecting device, the conductive portion in the circuit-embedded member is formed of a leaf spring having a restoring force from the side surface of the sealing portion toward the housing member. be able to.
Further, the sealing portion in the circuit-embedded member may be provided behind the conductive portion, and may have a protrusion protruding from the side surface of the sealing portion toward the housing member.
The sealing portion of the circuit-embedded member may further include another protrusion provided on the back side of the protrusion of the sealing portion and protruding from the side surface of the sealing portion toward the housing member. It can be a feature.
Further, the accommodation member is provided with a hole penetrating an inner surface and an outer surface of the accommodation member, and the conductive portion provided in the circuit-embedded member is disposed at a portion where the hole is formed. The method may further include a step of, after accommodating the circuit-embedded member in a member, joining the accommodating member and the conductive portion at a site where the hole is formed.

According to the present invention, the reliability of the electrical connection between the piezoelectric element and the processing circuit can be improved.

It is a schematic block diagram of the pressure detection system which concerns on embodiment. It is a side view of a pressure detection device. It is sectional drawing (III-III sectional drawing of FIG. 2) of a pressure detection apparatus. FIG. 4 is an enlarged cross-sectional view of a front end side (IV region in FIG. 3) of the pressure detection device. FIG. 6 is an exploded cross-sectional view of a first inner casing, a second inner casing, a pressure member, a first insulating member, and a second insulating member that constitute the pressure detection device. (A) is a perspective view of the 1st accommodating member provided in the pressure detecting device, and (b) is a perspective view of the 2nd accommodating member provided in the pressure detecting device. It is a perspective view of a circuit built-in member provided in the pressure detection device. It is a perspective view of a circuit built-in member before bending a metal plate. FIG. 9 is a cross-sectional view (IX-IX cross-sectional view of FIG. 7) of the circuit built-in member. It is a schematic block diagram of the circuit board provided in the circuit built-in member.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[Structure of pressure detection system]
FIG. 1 is a schematic configuration diagram of a pressure detection system 1 according to an embodiment.
This pressure detection system 1 is based on the pressure detection device 20 that detects the pressure (combustion pressure) in the combustion chamber C of the internal combustion engine 10 and the pressure detected by the pressure detection device 20 while supplying power to the pressure detection device 20. A control device 100 that controls the operation of the internal combustion engine 10 and a connection cable 80 that electrically connects the pressure detection device 20 and the control device 100 are provided.

Here, the internal combustion engine 10 whose pressure is to be detected includes a cylinder block 11 having a cylinder formed therein, 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. And a cylinder head 13 constituting the. Further, the cylinder head 13 is provided with a communication hole 13a that communicates the combustion chamber C with the outside. Then, the pressure detection device 20 is attached to the internal combustion engine 10 by inserting the tip end side of the pressure detection device 20 into the communication hole 13a and fixing the pressure detection device 20 to the cylinder head 13. Here, the cylinder block 11, the piston 12, and the cylinder head 13 that form the internal combustion engine 10 are made of a conductive metal material such as cast iron or aluminum.

[Structure of pressure detector]
FIG. 2 is a side view of the pressure detection device 20. 3 is a sectional view of the pressure detection device 20 (III-III sectional view of FIG. 2). Further, FIG. 4 is an enlarged cross-sectional view of the tip side of the pressure detection device 20 (IV region in FIG. 3). Furthermore, FIG. 5 shows that the first inner casing 35, the second inner casing 36, the pressurizing member 49, the first insulating member 51, and the second insulating member 52 that constitute the pressure detection device 20 (for details of each, see FIG. It is an exploded sectional view of (to be described later).

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

(Construction of case)
The housing unit 30 includes a distal end external housing 31, a diaphragm head 32 attached to the distal end side of the distal end external housing 31, an intermediate external housing 33 attached to the rear end side of the distal end external housing 31, A rear end external housing 34 attached to the rear end side of the intermediate outer housing 33 is provided. In addition, the housing unit 30 includes a first inner housing 35 attached to the rear end side of the diaphragm head 32 inside the front outer housing 31 and a first inner housing inside the front outer housing 31. It further includes a second inner casing 36 attached to the rear end side of the casing 35.

(Tip external housing)
The tip external housing 31 is a member having a hollow structure and having a tubular shape as a whole. The tip outer casing 31 is made of a metal material such as stainless steel having conductivity and high heat resistance and acid resistance.

(Diaphragm head)
The diaphragm head 32 is a disk-shaped member 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 this example, the diaphragm head 32 and the tip outer casing 31 are made of the same material.

As shown in FIG. 4, in particular, the diaphragm head 32 has a surface center concave portion 32b formed in the central portion on the tip side, and a pressure receiving surface (surface) that receives pressure when exposed to the outside (combustion chamber C side). 32a. Further, the diaphragm head 32 has a back surface annular recess 32c formed by notching the back surface, which is the back side of the pressure receiving surface 32a, in an annular shape, and the existence of the back surface annular recess 32c results in the central portion of the pressure receiving surface 32a ( It has a rear surface central convex portion 32d which projects from the front surface central concave portion 32b) to the rear end side. Further, the diaphragm head 32 has a back surface annular flat portion 32e formed by notching the peripheral edge portion on the back surface of the pressure receiving surface 32a in an annular shape, and the existence of the back surface annular recess 32c and the back surface annular flat portion 32e. It has a back surface annular convex portion 32f protruding from the periphery of the central convex portion 32d to the rear end side.

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

[Intermediate external housing]
The intermediate outer casing 33 is a member having a hollow structure and having a tubular shape as a whole. The intermediate outer casing 33 is made of a metal material such as stainless steel having conductivity and high heat resistance and acid resistance.

The front end side of the intermediate outer casing 33 is fitted into the rear end side of the front outer casing 31. The boundary between the intermediate outer casing 33 and the tip outer casing 31 is laser-welded over the entire circumference of the outer peripheral surface.

[Rear-end external housing]
The rear end outer casing 34 is a member having a hollow structure and having a tubular shape as a whole. The rear end outer casing 34 is made of a metal material such as stainless steel having conductivity and high heat resistance and acid resistance.

The front end side of the rear end external housing 34 is fitted into the rear end side of the intermediate external housing 33. Laser welding is not applied to the boundary between the rear end outer casing 34 and the intermediate outer casing 33.

[First internal housing]
The first inner housing 35 is a member having a hollow structure and having a tubular shape as a whole. The first inner casing 35 is made of a metal material such as stainless steel having conductivity and high heat resistance and acid resistance.

As shown in FIG. 5, in particular, the first inner casing 35 includes a first tip tubular portion 351 located closest to the tip end and a first rear end tubular portion located at the rear end side of the first tip tubular portion 351. And a portion 352. In the first inner casing 35, the outer diameter of the first rear end tubular portion 352 is larger than that of the first front end tubular portion 351, and the first outer stepped portion 353 is provided at the boundary between the two. ing. Further, the through hole provided inside the first inner casing 35 has an inner diameter that gradually increases from the front end side toward the rear end side, and the inner diameter of the first rear end tubular portion 352 is increased. A first inner stepped portion 354 is provided at the portion that becomes.

The front end side of the first inner casing 35 abuts on the rear end side of the diaphragm head 32. More specifically, the tip side surface of the first outer step portion 353 of the first inner casing 35 abuts against the rear end side surface of the rear annular protrusion 32f of the diaphragm head 32. At this time, the first distal end tubular portion 351 of the first inner housing 35 is located inside the rear annular recess 32c of the diaphragm head 32. Then, laser welding is applied to the boundary between the first inner casing 35 and the diaphragm head 32 over the entire circumference of the outer peripheral surface.

[Second internal casing]
The second inner casing 36 is a member having a hollow structure and having a tubular shape as a whole. The second inner casing 36 is made of a metal material such as stainless steel having conductivity and high heat resistance and acid resistance.

As shown in FIG. 5, in particular, the second inner casing 36 includes a second front end tubular portion 361 located closest to the front end and a second rear end tubular portion located at the rear end side of the second front end tubular portion 361. And a shape portion 362. In the second inner casing 36, the outer diameter of the second rear end tubular portion 362 is larger than that of the second front end tubular portion 361, and the second outer stepped portion 363 is formed at the boundary between the two. ing. Further, the through hole provided inside the first inner casing 35 has a substantially constant inner diameter.

The tip end side of the second inner casing 36, that is, the tip end side of the second tip tubular portion 361 is housed inside the first rear end tubular portion 352 of the first inner casing 35. Further, the surface of the second inner casing 36 on the front end side abuts on the surface of the second insulating member 52 (details will be described later) on the rear end side. At this time, the rear end side of the second front end tubular portion 361 and the second rear end tubular portion 362 are exposed at the rear end side of the first inner casing 35. Then, laser welding is performed on the boundary between the second inner casing 36 and the first inner casing 35 over the entire circumference of the outer peripheral surface.

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

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

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

Next, a case where the piezoelectric lateral effect is used for the piezoelectric element 41 will be exemplified. The piezoelectric lateral effect means that when an external force is applied to a stress applying axis located 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. The piezoelectric body may be formed by laminating a plurality of piezoelectric bodies that are thinly formed in the shape of a thin plate. By laminating in this way, it is possible to efficiently collect the charges generated in the piezoelectric body and increase the sensitivity of the sensor. Examples of piezoelectric materials that can be used in the piezoelectric element 41 include Langasite-based crystals (Langasite, Langatate, Langanite, LTGA), quartz, gallium phosphate, etc. that have a piezoelectric longitudinal effect and a piezoelectric lateral effect. can do.

[Tip electrode member]
The tip electrode member 42 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 conductivity and high heat resistance. The tip electrode member 42 is arranged inside the tip external housing 31 and on the tip side of the piezoelectric element 41, and the rear end side surface of the tip electrode member 42 contacts the tip side surface of the piezoelectric element 41. It has become. The outer diameter of the tip electrode member 42 is larger than the outer diameter of the piezoelectric element 41.

[Tip insulation member]
The tip insulating member 43 is a member having a cylindrical shape as a whole. The tip end insulating member 43 is made of a ceramic material such as alumina having an insulating property and a high heat resistance. The tip insulating member 43 is arranged inside the tip outer casing 31 and on the tip side of the tip electrode member 42, and the rear end side surface of the tip insulating member 43 contacts the tip side surface of the tip electrode member 42. It is supposed to do. On the other hand, the tip end side surface of the tip end insulating member 43 comes into contact with the back end side surface of the rear surface center convex portion 32 d provided on the diaphragm head 32. Further, the outer diameter of the tip insulating member 43 is smaller than the outer diameter of the tip electrode member 42 and larger than the outer diameter of the back surface center convex portion 32d of the diaphragm head 32.

[Rear end electrode member]
The rear end electrode member 44 is a member having a cylindrical shape as a whole. The rear end electrode member 44 is made of a metal material such as stainless steel having conductivity and high heat resistance. The rear end electrode member 44 is disposed inside the front end outer casing 31 and on the rear end side of the piezoelectric element 41, and the front end side surface of the rear end electrode member 44 corresponds to the rear end side surface of the piezoelectric element 41. It comes in contact. The outer diameter of the rear electrode member 44 is larger than the outer diameter of the piezoelectric element 41.

[Rear end insulating member]
The rear end insulating member 45 is a member having a hollow structure and having an annular shape (cylindrical shape) as a whole. The rear end insulating member 45 is made of a ceramic material such as alumina having an insulating property and a high heat resistance. The rear end insulating member 45 is arranged inside the front outer casing 31 and on the rear end side of the rear end electrode member 44, and the surface of the rear end insulating member 45 on the front end side is the rear end of the rear end electrode member 44. It comes in contact with the side surface. The outer diameter of the rear end insulating member 45 is larger than the outer diameter of each of the piezoelectric element 41, the front electrode member 42, and the rear electrode member 44.

[First coil spring]
The first coil spring 46 is a member having a spiral shape as a whole, and is configured to expand and contract in the center line direction. The first coil spring 46 is made of a conductive metal material such as brass, and its surface is plated with gold. The first coil spring 46 is arranged inside the tip outer casing 31. More specifically, the tip end side of the first coil spring 46 is disposed inside the through hole provided in the rear end insulating member 45, and the tip end thereof is the rear end side surface of the rear end electrode member 44. To come into contact with. On the other hand, the rear end side of the first coil spring 46 projects to the rear end side of the rear end insulating member 45. Further, the outer diameter of the first coil spring 46 is smaller than the inner diameter of the through hole provided in the rear end insulating member 45.

[Conductive member]
The conductive member 47 is a rod-shaped member as a whole. The conductive member 47 is made of a conductive metallic material such as brass, and its surface is plated with gold. The conductive member 47 includes a tip rod portion 471 located closest to the tip end side, an intermediate rod portion 472 located at the rear end side of the tip rod portion 471, and a rear end rod portion 473 located at the rear end side of the intermediate rod portion 472. And have. Further, in the conductive member 47, the outer diameter increases in the order of the front end rod-shaped portion 471, the intermediate rod-shaped portion 472, and the rear end rod-shaped portion 473. The conductive member 47 is arranged inside the tip outer casing 31. More specifically, the tip end side of the conductive member 47, that is, the tip end side of the tip end rod portion 471 is inserted into the rear end side of the first coil spring 46, and is arranged inside the rear end insulating member 45. However, unlike the first coil spring 46, the tip of the tip rod portion 471 is not in contact with the surface on the rear end side of the rear electrode member 44. At this time, the rear end of the first coil spring 46 abuts on the boundary portion (step portion) between the tip rod portion 471 and the intermediate rod portion 472 of the conductive member 47. As a result, the first coil spring 46 is sandwiched between the rear end electrode member 44 and the conductive member 47, so that the first coil spring 46 is compressed in the center line direction. On the other hand, the intermediate rod-shaped portion 472 and the rear end rod-shaped portion 473 of the conductive member 47 project to the rear end side of the rear end insulating member 45. The outer diameter of the tip rod portion 471 is smaller than the inner diameter of the first coil spring 46, and the outer diameter of the intermediate rod portion 472 is larger than the inner diameter of the first coil spring 46.

[Holding member]
The holding member 48 is a member having a hollow structure and having a tubular shape as a whole. The holding member 48 is made of an insulating synthetic resin material such as PPT (Polypropylene Terephthalate). The holding member 48 has a tip portion located closest to the tip end side, an intermediate portion located at the rear end side of the tip portion, and a rear end portion located at the rear end side of the intermediate portion. The outer diameter of the holding member 48 increases in the order of the front end portion, the intermediate portion, and the rear end portion. The holding member 48 is arranged so as to straddle the inside of the tip outer casing 31 and the inside of the intermediate outer casing 33. The conductive member 47 is housed and held inside the holding member 48. More specifically, the holding member 48 houses the rear end side of the conductive member 47, that is, the rear end side of the rear end rod-shaped portion 473. As a result, of the conductive member 47, the tip rod portion 471 and the intermediate rod portion 472 and the tip end side of the trailing end rod portion 473 project to the tip end side of the holding member 48. On the other hand, the rear end of the holding member 48 is formed with a concave portion extending from the rear end side toward the front end side. Further, the inner diameter of the hole provided in the holding member 48 is slightly larger than the outer diameter of the rear end rod-shaped portion 473 of the conductive member 47, and the conductive member 47 and the holding member 48 are press-fitted (an interference fit). ) Are integrated.

(Pressure member)
The pressing member 49 is a member having a hollow structure and having a tubular shape as a whole. The pressing member 49 is made of a metal material such as stainless steel having conductivity and high heat resistance. The pressurizing member 49 is arranged inside the tip outer casing 31 and across the inside of the first inner casing 35 and the inside of the second inner casing 36.

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

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

The outer diameter of the first tubular portion 491 of the pressure member 49 is smaller than the inner diameter of the first inner casing 35 on the tip side of the first inner step 354. The outer diameter of each of the second tubular portion 492, the third tubular portion 493, and the fourth tubular portion 494 is larger than the inner diameter of the first inner casing 35 on the rear end side of the first inner step portion 354. It is getting smaller. Further, the outer diameter of the fourth tubular portion 494 is smaller than the inner diameter of the second inner casing 36.

On the other hand, the inner diameter of the through hole provided in the pressing member 49 is larger than the outer diameter of each of the piezoelectric element 41, the tip electrode member 42, the rear end electrode member 44, and the rear end insulating member 45. Further, the inner diameter of the opening on the tip side of the through hole provided in the pressing member 49 is larger than the outer diameter of the tip insulating member 43.

[Insulation pipe]
The insulating pipe 50 is a member having a hollow structure and having a tubular shape as a whole. The insulating pipe 50 is made of an insulating synthetic resin material such as LCP (Liquid Crystal Polymer). The insulating pipe 50 is arranged inside the tip outer casing 31 and inside the pressing member 49. The surface of the insulating pipe 50 on the front end side comes into contact with the surface of the fourth step portion 498 provided on the pressing member 49 on the rear end side. Inside the insulating pipe 50, the piezoelectric element 41, the front end electrode member 42, the rear end electrode member 44, and the front end side of the rear end insulating member 45 are housed. The outer diameter of the insulating pipe 50 is smaller than the inner diameter of the through hole provided in the pressing member 49 and larger than the inner diameter of the opening provided on the tip side of the through hole. The inner diameter of the insulating pipe 50 is larger than the outer diameters of the piezoelectric element 41, the tip electrode member 42, the rear end electrode member 44, and the rear end insulating member 45.

[First insulating member]
The first insulating member 51 is a member having a ring shape as a whole. The first insulating member 51 is made of a ceramic material such as alumina having an insulating property and a high heat resistance. The first insulating member 51 is arranged inside the tip outer casing 31, inside the first inner casing 35, and outside the pressing member 49. The front surface of the first insulating member 51 contacts the rear surface of the first inner stepped portion 354 of the first inner casing 35, and the rear surface of the first insulating member 51 is The pressing member 49 comes into contact with the surface of the second step portion 496 on the tip side. The outer diameter of the first insulating member 51 is smaller than the inner diameter of the first inner housing 35 on the rear end side of the first inner step 354. The inner diameter of the first insulating member 51 is larger than the outer diameter of the second tubular portion 492 of the pressure member 49.

[Second insulating member]
The second insulating member 52 is a ring-shaped member as a whole. Like the first insulating member 51, the second insulating member 52 is made of a ceramic material such as alumina that has insulating properties and high heat resistance. The second insulating member 52 is arranged inside the tip outer casing 31, inside the first inner casing 35, and outside the pressing member 49. The second insulating member 52 is arranged on the rear end side of the first insulating member 51. The front surface of the second insulating member 52 contacts the rear surface of the third step portion 497 of the pressing member 49, and the rear surface of the second insulating member 52 is the second internal portion. The housing 36 comes into contact with the surface of the second tip tubular portion 361 on the tip side. The outer diameter of the first insulating member 51 is smaller than the inner diameter of the first inner housing 35 on the rear end side of the first inner step 354. Further, the inner diameter of the first insulating member 51 is larger than the outer diameter of the fourth tubular portion 494 of the pressure member 49. In addition, in the present embodiment, the second insulating member 52 having the same size as the first insulating member 51 is used.

[Supporting member]
The support member 53 is a member having a hollow structure and having a tubular shape as a whole. The support member 53 is made of a metal material such as stainless steel having conductivity and high heat resistance. The support member 53 is arranged inside the tip outer casing 31, and the tip side thereof is arranged inside the pressure member 49. However, the rear end side of the support member 53 is in a state of protruding from the rear end of the pressing member 49. The front surface of the support member 53 is in contact with the rear surface of the rear insulating member 45. Further, laser welding is applied to the boundary between the support member 53 and the pressing member 49 over the entire circumference of the outer peripheral surface. Inside the support member 53, the rear end side of the first coil spring 46 and the front end sides of the conductive member 47 and the holding member 48 are housed. The outer diameter of the support member 53 is slightly smaller than the inner diameter of the through hole provided in the pressure member 49. The inner diameter of the through hole provided in the support member 53 is slightly larger than the outer diameter of the tip portion of the holding member 48.

[Second coil spring]
The second coil spring 54 is a member having a spiral shape as a whole, and is configured to expand and contract in the center line direction. The second coil spring 54 is made of a metal material such as stainless steel having conductivity and high heat resistance, and its surface is plated with gold. As described above, in the present embodiment, the first coil spring 46 and the second coil spring 54 are made of different materials. The second coil spring 54 is arranged inside the tip outer casing 31. More specifically, the tip end side of the second coil spring 54 is disposed on the rear end side of the support member 53 and outside the outer peripheral surface, and the tip end of the fourth coiled portion 494 of the pressurizing member 49. It comes in contact with the surface on the rear end side. Inside the second coil spring 54, the conductive member 47, the holding member 48, the support member 53, and the tip end side of the first housing member 55 are arranged. The outer diameter of the second coil spring 54 is smaller than the inner diameter of the tip outer casing 31. The inner diameter of the second coil spring 54 is larger than the outer diameter of the support member 53.

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

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

The first accommodating member 55 is positioned on the most distal end side of the first distal end portion 551, the first intermediate portion 552 located at the rear end side of the first distal end portion 551, and at the rear end side of the first intermediate portion 552. And a first rear end portion 553 that does. In the first accommodating member 55, the outer diameter of the first intermediate portion 552 is larger than that of the first tip portion 551, and the first tip step portion 554 is formed at the boundary portion between the two. Further, the outer diameter of the first rear end portion 553 is larger than that of the first intermediate portion 552, and the first rear end step portion 555 is formed at the boundary portion between the two. The first accommodating member 55 is arranged inside the tip outer casing 31. More specifically, the tip end side of the first accommodation member 55, that is, the tip end side of the first tip end portion 551 faces the rear end side of the support member 53, and is located outside the outer peripheral surface of the first tip end portion 551. Is opposed to the second coil spring 54. The rear end of the second coil spring 54 abuts the surface of the first housing member 55 on the front end side of the first front end step 554. As a result, the second coil spring 54 is compressed between the pressing member 49 and the first accommodating member 55, and is compressed in the center line direction. The leading ends of the conductive member 47 and the holding member 48 are housed inside the through hole provided in the first housing member 55. The outer diameters of the first tip portion 551, the first intermediate portion 552, and the first rear end portion 553 of the first housing member 55 are smaller than the inner diameter of the tip outer casing 31. The outer diameter of the first tip portion 551 is smaller than the inner diameter of the second coil spring 54, and the outer diameter of the first intermediate portion 552 is larger than the inner diameter of the second coil spring 54. Further, the inner diameter of the first accommodating member 55 is larger than the outer diameter of the holding member 48.

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

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

The second accommodating member 56 is positioned on the rear end side of the second front end portion 561, the second front end portion 561, the second intermediate portion 562 located on the rear end side of the second front end portion 561, and the rear end side of the second intermediate portion 562. Second rear end portion 563. In the second accommodating member 56, the outer diameter of the second intermediate portion 562 is larger than that of the second tip portion 561, and the second tip step portion 564 is formed at the boundary portion between the two. Further, the outer diameter of the second rear end portion 563 is larger than that of the second intermediate portion 562, and the second rear end stepped portion 565 is formed at the boundary between the two. Further, the second rear end portion 563 is formed with a circular round hole 566 (an example of a hole) that penetrates the outer peripheral surface (an example of an outer surface) and the inner peripheral surface (an example of an inner surface). The second accommodating member 56 is arranged so as to straddle the inside of the distal outer casing 31 and the inside of the intermediate outer casing 33. More specifically, the tip side of the second housing member 56, that is, the tip side of the second tip portion 561 is housed in the first rear end portion 553 of the first housing member 55, and the second tip step portion. The surface of the front end side of 564 comes into contact with the surface of the rear end side of the first rear end portion 553. In addition, the middle portion and the rear end portion of the holding member 48 are housed inside the through hole provided in the second housing member 56. The outer diameters of the second front end portion 561, the second middle portion 562, and the second rear end portion 563 of the second housing member 56 are smaller than the inner diameters of the front end outer casing 31 and the middle outer casing 33 that face each other. Is becoming The inner diameter of the second storage member 56 is larger than the outer diameter of the holding member 48. Furthermore, the outer diameter of the second front end portion 561 of the second storage member 56 is slightly larger than the inner diameter of the first rear end portion 553 of the first storage member 55, and the first storage member 55 and the second storage member 55 are accommodated. The member 56 is integrated by press fitting (tight fit). In addition, the 2nd accommodating member 56 may function as an accommodating member by itself, and may function as an accommodating member with the 1st accommodating member 55.

[Circuit built-in member]
As shown in FIG. 3, in particular, the circuit built-in member 57 houses the circuit board 91 and the circuit board 91 that performs various processes using an electronic circuit on an electric signal due to a weak electric charge output from the piezoelectric element 41. Accordingly, the sealing portion 92 that seals the circuit board 91 is provided. The circuit built-in member 57 is arranged inside the intermediate outer casing 33, and almost the entire region except a part on the rear end side is arranged inside the second accommodating member 56. Further, the front end side of the circuit built-in member 57 is adapted to be fitted in a recess provided on the rear end side of the holding member 48. A metal plate (details of which will be described later) provided on the front end side of the circuit-embedded member 57 comes into contact with the rear end side of the conductive member 47. Further, a metal plate (details will be described later) provided on the outer peripheral surface of the circuit built-in member 57 comes into contact with the inner peripheral surface of the second housing member 56. The details of the circuit built-in member 57 will be described later.

[Connecting member]
The connecting member 58 is a member having a columnar shape as a whole. The connecting member 58 includes a base material made of an insulating synthetic resin material such as PPT, and wiring and terminals made of a conductive metal material such as copper. The connecting member 58 is arranged so as to extend across the inside of the intermediate outer casing 33 and the inside of the rear end outer casing 34. The portion (outer peripheral surface) of the connecting member 58 facing the intermediate outer casing 33 or the rear end outer casing 34 is made of a synthetic resin material, and the metal material is not exposed at this portion. There is. The rear end side of the circuit built-in member 57 faces the front end side of the connection member 58, and a metal plate (details will be described later) provided on the circuit built-in member 57 is fitted into a terminal provided on the connection member 58. It is supposed to be. Further, on the rear end side of the connecting member 58, the respective conductor portions exposed on the front end side of the power supply line 81, the signal line 82 and the ground line 83 (the details of which will be described later) constituting the connection cable 80 are inserted. ing. The outer diameter of the connecting member 58 is slightly larger than the inner diameter of the intermediate outer casing 33 on the rear end side, and the intermediate outer casing 33 and the connecting member 58 are integrated by press fitting (tight fit). There is.

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

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

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

[First seal member]
The first seal member 71 is a member having an annular shape as a whole, and in this example, is configured by an angular ring having a quadrangular cross section. The first seal member 71 is made of a synthetic resin material such as PTFE having an insulating property and a high heat resistance and a high acid resistance. Then, the first seal member 71 is attached to the outer peripheral surface of the distal end external housing 31 forming the housing unit 30.

[Second seal member]
The second seal member 72 is a member having an annular shape as a whole, and in this example, is configured by an O-ring having a circular cross section. The second seal member 72 is also made of a synthetic resin material such as PTFE having an insulating property and high heat resistance and acid resistance. The second seal member 72 is attached to the outer peripheral surface of the rear end external housing 34 that constitutes the housing unit 30.

[Connection cable configuration]
The connection cable 80 includes a twisted power line 81, a signal line 82, and a ground line 83, and a covering member (not shown) that covers the outer circumferences of the power line 81, the signal line 82, and the ground line 83. .. Here, the power supply line 81, the signal line 82, and the grounding line 83 are each formed of a tin-plated annealed copper stranded wire and an insulating member that is made of silicon rubber or the like and covers the outer periphery of the conductor part for insulation. And a section. The covering member is made of an insulating rubber material or resin material. The connection cable 80 may be provided with a shield that shields the power supply line 81, the signal line 82, and the ground line 83, if necessary.

[Construction of circuit built-in members]
Next, the details of the circuit built-in member 57 described above will be described.
FIG. 7 is a perspective view of the circuit built-in member 57 provided in the pressure detection device 20. 8 is a perspective view of the circuit built-in member 57 before the metal plate is bent (details will be described later). Further, FIG. 9 is a cross-sectional view of the circuit built-in member 57 (IX-IX cross-sectional view of FIG. 7). In FIGS. 7 and 8, the lower left side in the drawings is the front end side, and the upper right side in the drawings is the rear end side. Further, in FIG. 9, the left side in the figure is the front end side, and the right side in the figure is the rear end side.

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

(Circuit board)
FIG. 10 is a schematic configuration diagram of the circuit board 91 provided on the circuit-embedded member 57. However, FIG. 10 also shows the connection relationship between the circuit board 91 and the input signal plate 93, the input ground plate 94, the power receiving plate 95, the output signal plate 96, and the output ground plate 97.

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

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

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

The processing circuit 912 includes an integrating circuit 912a that integrates a charge signal input from the piezoelectric element 41 through the input signal terminal 91a and converts the charge signal into a voltage signal, and amplifies the converted voltage signal to output the output signal terminal. It has the amplifier circuit 912b which outputs to 91d. Here, the integration circuit 912a and the amplification circuit 912b are supplied with the power supply voltage for operating them through the power receiving terminal 91c. The grounds of the integration circuit 912a and the amplification circuit 912b are connected to the input ground terminal 91b and the output ground terminal 91e. In addition, in this example, the processing circuit 912 is configured by a so-called integrated circuit (IC).

(Sealing part)
The sealing portion 92 is a member having a columnar shape as a whole. The sealing portion 92 is made of an insulating synthetic resin material such as epoxy. The sealing portion 92 includes a small diameter portion 921 located closest to the front end side, a medium diameter portion 922 located at the rear end side of the small diameter portion 921, and a large diameter portion 923 located at the rear end side of the medium diameter portion 922. I have it. The outer diameter of the sealing portion 92 increases in the order of the small diameter portion 921, the medium diameter portion 922, and the large diameter portion 923. The small diameter portion 921, the medium diameter portion 922, and the large diameter portion 923 each have a polygonal (eg, octagonal) cross-sectional shape. Here, in the present embodiment, the circuit board 91 is housed inside the medium diameter portion 922 of the sealing portion 92.

Further, the medium diameter portion 922 is provided with a front surface 922a and a back surface 922b located on the back side of the front surface 922a. Here, the front surface 922a and the back surface 922b have a substantially parallel positional relationship with the front surface and the back surface of the printed wiring board 911 in the circuit board 91. A surface protrusion group 924 formed by connecting a plurality of protrusions is provided on the rear end side of the surface 922a. On the other hand, on the rear end side of the back surface 922b, a back surface projection group 925 formed by connecting a plurality of projections is provided. The surface protrusion group 924 includes a surface first protrusion 924a (an example of a protrusion) and a surface second protrusion 924b located on the rear end side of the surface first protrusion 924a. The back surface projection group 925 includes a back surface first projection 925a (an example of another projection) and a back surface second projection 925b located on the rear end side of the back surface first projection 925a. Here, the back surface first projection 925a is located on the back side of the front surface first projection 924a, and the back surface second projection 925b is located on the back side of the surface second projection 924b. The front surface first projection 924a, the front surface second projection 924b, the back surface first projection 925a, and the back surface second projection 925b each have an inclined surface that is inclined so as to increase the outer diameter from the front end side toward the rear end side. The rear end side of the inclined surface has a shape in which a flat surface that makes the outer diameter constant from the front end side to the rear end side is connected. Here, the heights of the front surface first projection 924a and the front surface second projection 924b with respect to the front surface 922a and the heights of the back surface first projection 925a and the back surface second projection 925b with respect to the back surface 922b are set to the same size. .. The outer diameter of the middle diameter portion 922 from the front surface second protrusion 924b to the back surface second protrusion 925b is smaller than the outer diameter of the large diameter portion 923. The outer diameters of the small-diameter portion 921 and the medium-diameter portion 922 on the front end side are smaller than the inner diameter of the second rear end portion 563 of the second accommodating member 56. Further, the outer diameter of the middle diameter portion 922 from the front surface first projection 924a to the back surface first projection 925a is also smaller than the inner diameter of the second rear end portion 563. On the other hand, the outer diameter of the large diameter portion 923 is slightly larger than the inner diameter of the second rear end portion 563.

(Input signal board)
The input signal plate 93 is a member having a plate shape (a strip shape) as a whole. The input signal plate 93 is made of a metal material such as brass having conductivity and elasticity, and its surface is plated with gold. The input signal plate 93 is disposed so as to project from the surface of the sealing portion 92 on the tip side of the small diameter portion 921 to the tip side. However, the rear end side of the input signal plate 93 is disposed inside the sealing portion 92 and is fixed using the sealing portion 92. The tip end side of the input signal plate 93 is bent so as to face upward in FIG. The input signal plate 93 contacts the rear end side of the conductive member 47.

(Input ground plate)
The input ground plate 94, which is an example of a conductive portion, is a member having a plate shape (F shape) as a whole. The input ground plate 94 is also made of a conductive and elastic metal material such as brass, and its surface is plated with gold. The input ground plate 94 includes a first protrusion 941 and a second protrusion 942, which are provided so as to protrude laterally from the outer peripheral surface (other than the front surface 922a and the back surface 922b) of the middle diameter portion 922 in the sealing portion 92, and these. The main body 943 is connected to the first protrusion 941 and the second protrusion 942. However, one end sides of the first projecting portion 941 and the second projecting portion 942 are arranged inside the sealing portion 92 and are fixed using the sealing portion 92. Here, the second protrusion 942 is arranged on the rear end side of the first protrusion 941. Further, the main body portion 943 has a strip shape extending from the front end side toward the rear end side. The first projecting portion 941 and the second projecting portion 942 are bent upward along the shape of the outer peripheral surface of the middle diameter portion 922 in FIG. 7, and the main body portion 943 is provided on the surface 922a. And the surface projection group 924. Here, the size of the outer diameter in which the thickness of the main body portion 943 of the input ground plate 94 is added to the outer diameter from the front surface first protrusion 924a to the back surface first protrusion 925a in the middle diameter portion 922 is the second accommodating member. It is slightly larger than the inner diameter of the second rear end portion 563 at 56. In addition, in this example, in the processing circuit 912 shown in FIG. 10, the ground system related to the power source and the ground system related to the signal are actually separated, and the ground system related to the power source is connected to the first projecting portion 941. The grounding system for each is connected to the second protruding portion 942. The main body portion 943 of the input ground plate 94 comes into contact with the inner peripheral surface of the second housing member 56.

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

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

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

[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: an example of one pole) on the rear end side of the piezoelectric element 41 is electrically connected to the rear end electrode member 44, the first coil spring 46, and the conductive member 47. Further, the conductive member 47 is electrically connected to the input signal board 93 provided on the circuit built-in member 57. Then, the input signal board 93 is electrically connected to the input signal terminal 91a of the circuit board 91 provided on the same circuit built-in member 57. In the following, an electrical signal from the rear end side surface of the piezoelectric element 41 to the input signal terminal 91 a of the circuit board 91 via the rear end electrode member 44, the first coil spring 46, the conductive member 47, and the input signal plate 93. The route is called a "positive route".

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

(Case path)
On the other hand, in the pressure detection device 20, the diaphragm head 32 is electrically connected to the tip outer casing 31, the middle outer casing 33, and the rear end outer casing 34. Further, the diaphragm head 32 is electrically connected to the first inner casing 35 and the second inner casing 36. In the following, an electrical path from the second inner casing 36 to the first inner casing 35, the diaphragm head 32, the front outer casing 31, the middle outer casing 33, and the rear outer casing 34 will be referred to as “casing”. Body path”. When the pressure detection device 20 is attached to the cylinder head 13 of the internal combustion engine 10 shown in FIG. 1, for example, the tip outer housing 31 contacts the inner peripheral surface of the communication hole 13a. At this time, the cylinder head 13 (and the cylinder block 11) and the casing path have substantially the same potential.

(Relationship between positive and negative paths)
Here, in the pressure detection device 20 of the present embodiment, the 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 rear end insulating member 45, the holding member 48, the insulating pipe 50, and the air gap formed between the two paths.

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

(Relation between case route and positive route)
Furthermore, in the pressure detection device 20, as a result, the casing path exists outside the positive path. In other words, the positive path is housed inside the housing path. Then, as described above, the positive path and the negative path are electrically insulated from each other, and the negative path and the housing path are electrically insulated from each other, so that the housing path and the positive path are separated from each other. However, it means that it is electrically insulated.

[Circuit manufacturing procedure]
Now, the manufacturing procedure of the circuit-embedded member 57 will be described with reference to FIGS. 7 to 9.
First, the input signal plate 93, the input ground plate 94, the power receiving plate 95, the output signal plate 96, and the output ground plate 97 are positioned and connected to the circuit board 91 to obtain a connected body.

Next, the connecting body is set in a transfer molding device, and transfer molding is performed using an insulating synthetic resin material (here, epoxy resin) to form a sealing portion 92, and then the transfer molding device is used. Take it out. The circuit built-in member 57 taken out from the transfer mold apparatus is in the state shown in FIG. 8, and each end portion of the input signal plate 93, the input ground plate 94, the power receiving plate 95, the output signal plate 96, and the output ground plate 97. , But protrudes from the sealing portion 92 in a flat state.

Subsequently, in the circuit built-in member 57 shown in FIG. 8, with respect to each of the input signal plate 93, the input ground plate 94, the power receiving plate 95, the output signal plate 96, and the output ground plate 97 protruding from the sealing portion 92, Bending is applied. As a result, the circuit built-in member 57 shown in FIG. 7 and the like is obtained.

[Manufacturing procedure of pressure detector]
Subsequently, a manufacturing procedure of the above-described pressure detection device 20 will be described with reference to FIGS. 2 to 10.
(Assembly of the first structure)
First, the insulating pipe 50 is inserted from the rear end side into the pressure member 49 having the first cylindrical portion 491 as the front end side and the fourth cylindrical portion 494 as the rear end side. At this time, the end surface of the insulating pipe 50 abuts the rear end surface of the fourth step portion 498 provided inside the pressing member 49. As a result, the outer peripheral surface of the insulating pipe 50 faces the inner peripheral surface of the pressing member 49.

Next, the front end electrode member 42, the piezoelectric element 41, the rear end electrode member 44, and the rear end insulating member 45 are inserted in this order from the rear end side with respect to the pressing member 49. At this time, the tip side surface of the tip electrode member 42 abuts on the rear side surface of the fourth step portion 498 provided inside the pressing member 49. The front end surface of the piezoelectric element 41 is on the rear end surface of the front end electrode member 42, and the front end surface of the rear end electrode member 44 is on the rear end surface of the piezoelectric element 41. The front end side surface of the rear end insulating member 45 abuts on the rear end side surface of the member 44. As a result, the outer peripheral surfaces of the tip electrode member 42, the piezoelectric element 41, the rear end electrode member 44, and the rear end insulating member 45 face the inner peripheral surface of the insulating pipe 50.

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

Next, the support member 53 is moved (moved back and forth) along the center line direction with respect to the pressure member 49, so that the load applied to the piezoelectric element 41 via each member is adjusted. Then, with the load being adjusted, the first structure is obtained by performing laser welding on the boundary between the pressing member 49 and the supporting member 53 over the entire circumference.

(Assembly of the second structure)
In addition, the back surface, that is, the rear end side of the diaphragm head 32 and the front end side of the first internal housing 35 are opposed to each other in a step different from the manufacturing of the first structure. Then, the surface on the front end side of the first outer step portion 353 of the first inner casing 35 is abutted against the rear end side surface of the back surface annular convex portion 32f of the diaphragm head 32. Along with this, the first distal end tubular portion 351 of the first inner casing 35 is arranged in the rear annular recess 32 c of the diaphragm head 32. Then, in this state, the second structure is obtained by performing laser welding on the boundary between the diaphragm head 32 and the first inner casing 35 over the entire circumference.

(Assembly of the third structure)
Next, the tip end insulating member 43 is inserted into the first inner casing 35 of the second structure from the rear end side. At this time, the tip end side surface of the tip end insulating member 43 abuts the rear end side surface of the diaphragm head 32 on the back end side central convex portion 32d.

Then, the first insulating member 51 is inserted into the first inner casing 35 of the second structure from the rear end side. At this time, the surface on the front end side of the first insulating member 51 abuts on the surface on the rear end side of the first inner stepped portion 354 in the first inner casing 35. As a result, the outer peripheral surface of the first insulating member 51 faces the inner peripheral surface of the first inner casing 35 on the rear end side.

Next, the first structure is inserted into the first inner casing 35 of the second structure from the rear end side with the tip electrode member 42 as the front end side. At this time, the tip end surface of the tip electrode member 42 abuts on the tip end surface of the tip insulating member 43, and the second step in the pressing member 49 contacts the tip end surface of the first insulating member 51. The tip side surface of the portion 496 abuts. As a result, the outer peripheral surface of the second tubular portion 492 of the pressing member 49 faces the inner peripheral surface of the first insulating member 51. At this time, an air gap is formed between the outer peripheral surface of the pressing member 49 on the tip side (the first cylindrical portion 491 side) and the inner peripheral surfaces of the diaphragm head 32 and the first inner casing 35. To be done. At this time, an air gap is also formed between the surface of the pressing member 49 on the front end side of the first stepped portion 495 and the surface of the first inner casing 35 on the rear end side of the first inner stepped portion 354. It is formed. Further, at this time, an air gap is also formed between the outer peripheral surface of the third tubular portion 493 of the pressing member 49 and the inner peripheral surface of the first inner casing 35. Furthermore, at this time, the rear end side of the fourth tubular portion 494 of the pressurizing member 49 projects outward (rear end side) from the rear end of the first inner casing 35.

Then, the second insulating member 52 is inserted from the rear end side into the first inner casing 35 of the second structure. At this time, the surface on the front end side of the second insulating member 52 abuts on the surface on the rear end side of the third step portion 497 of the pressing member 49. As a result, the inner peripheral surface of the second insulating member 52 faces the outer peripheral surface of the fourth tubular portion 494 of the pressing member 49. The outer peripheral surface of the second insulating member 52 faces the inner peripheral surface of the first inner casing 35.

Next, the second inner housing 36 is inserted into the first inner housing 35 of the second structure from the rear end side with the second front end tubular portion 361 on the front end side. At this time, the surface on the front end side of the second front end tubular portion 361 of the second inner housing 36 abuts on the surface on the rear end side of the second insulating member 52. As a result, the inner peripheral surface of the second inner casing 36 faces the outer peripheral surface of the fourth tubular portion 494 of the pressing member 49 via the air gap. In addition, the outer peripheral surface of the second inner casing 36 on the front end side faces the inner peripheral surface of the first inner casing 35 on the rear end side. Further, the second rear end tubular portion 362 of the second inner casing 36 projects outside (rear end side) of the rear end of the first inner casing 35. As a result, the surface of the second inner casing 36 on the front end side of the second outer stepped portion 363 and the surface of the first inner casing 35 on the rear end side of the first rear end tubular portion 352 are separated by an air gap. Face each other.

Then, by moving (advancing and retracting) the second inner casing 36 with respect to the first inner casing 35 along the center line direction, the load applied to the piezoelectric element 41 via each member is adjusted. Then, with the load being adjusted, the third structure is obtained by performing laser welding on the boundary between the first inner casing 35 and the second inner casing 36 over one round.

(Assembly of Fourth Structure)
Next, the tip external housing 31 is inserted into the third structure from the rear end side. At this time, the front end side surface of the front end external housing 31 abuts the rear end side flat surface 32e of the diaphragm head 32 on the rear end side. Further, at this time, each component other than the diaphragm head 32 in the third structure is housed inside the tip external housing 31. Further, at this time, the diaphragm head 32 forming the third structure is exposed to the outside together with the tip external housing 31 with the pressure receiving surface 32a and the front surface central recess 32b facing outward. Then, in this state, the fourth structure is obtained by performing laser welding on the boundary portion between the tip external housing 31 and the diaphragm head 32 over the entire circumference.

(Assembly of fifth structure)
Further, in a step different from the step of manufacturing the fourth structure, the conductive member 47 is inserted into the holding member 48 from the rear end side with the front end rod-shaped portion 471 as the front end side. At this time, the leading end rod-shaped portion 471 and the intermediate rod-shaped portion 472 of the conductive member 47 and the leading end side of the trailing end rod-shaped portion 473 are projected to the leading end side of the holding member 48. As a result, the rear end side of the rear end rod portion 473 of the conductive member 47 faces the inner peripheral surface of the holding member 48. Then, the fifth structure is obtained by fitting the circuit built-in member 57 into the concave portion provided on the rear end side of the holding member 48 from the rear end side with the small diameter portion 921 of the sealing portion 92 being the front end side. .. At this time, the input signal plate 93 provided in the circuit built-in member 57 contacts the rear end of the rear end rod portion 473 of the conductive member 47.

(Assembly of sixth structure)
Next, the third insulating member 60 is inserted from the rear end side into the front external housing 31 of the fourth structure. At this time, the tip-side surface of the annular portion provided on the rear-end side of the third insulating member 60 abuts the rear-end side surface of the tip-end external casing 31. As a result, the outer peripheral surface of the cylindrical portion provided on the front end side of the third insulating member 60 faces the inner peripheral surface of the front outer casing 31.

Subsequently, the second coil spring 54 is inserted from the rear end side into the front end external housing 31 of the fourth structure, and the first accommodation member 55 is inserted with the first front end portion 551 being the front end side. At this time, the tip of the second coil spring 54 abuts the surface of the pressing member 49 on the rear end side of the fourth tubular portion 494. Further, the first tip portion 551 of the first housing member 55 is housed inside the rear end side of the second coil spring 54, and the rear end of the second coil spring 54 is provided on the tip side surface of the first tip stepped portion 554. bump into. Along with this, the second coil spring 54 is compressed in the center line direction. Further, as a result, the outer peripheral surfaces of the second coil spring 54 and the first accommodating member 55 face the inner peripheral surface of the tip external housing 31 via the air gap. However, the outer peripheral surface of the first rear end portion 553 of the first accommodating member 55 faces the inner peripheral surface of the front outer casing 31 via the third insulating member 60.

Next, the second housing member 56 is inserted from the rear end side into the outer front end housing 31 of the fourth structure with the second front end portion 561 being the front end side. At this time, the second front end portion 561 located on the front end side of the second storage member 56 fits inside the first rear end portion 553 provided on the rear end side of the first storage member 55. Further, at this time, the surface of the second housing member 56 on the tip side of the second rear end step 565 abuts on the surface of the third insulating member 60 on the rear end side of the annular portion. As a result, the outer peripheral surface of the second intermediate portion 562 of the second accommodating member 56 faces the inner peripheral surface of the cylindrical portion of the third insulating member 60.

Next, the first coil spring 46 is inserted from the rear end side into the front external housing 31 of the fourth structure. At this time, the tip end of the first coil spring 46 abuts on the rear end side surface of the rear end electrode member 44 through the through hole provided in the rear end insulating member 45.

Subsequently, the fifth structure is inserted into the front external housing 31 of the fourth structure from the rear end side with the front end bar-shaped portion 471 of the conductive member 47 as the front end side.

At this time, the conductive member 47 exposed on the tip side of the fifth structure is housed in the support member 53. However, the tip rod portion 471 of the conductive member 47 projects into the tip side of the support member 53 and is accommodated in the first coil spring 46. At this time, the tip side surface of the step portion between the tip rod-shaped portion 471 and the intermediate rod-shaped portion 472 provided on the conductive member 47 abuts on the rear end of the first coil spring 46. Along with this, the first coil spring 46 is compressed in the center line direction. As a result, the leading end side of the conductive member 47 faces the support member 53 via the air gap.

Further, the holding member 48 located on the intermediate side of the fifth structure is accommodated so as to extend across the support member 53, the first accommodating member 55, and the second accommodating member 56. At this time, one step portion provided on the holding member 48 abuts on a step provided on the back side of the first rear end step portion 555 of the first accommodating member 55, and is provided on the rear end side of the step portion. The other step portion comes into contact with a step provided on the back side of the second rear end step portion 565 of the second accommodating member 56. As a result, the outer peripheral surface of the holding member 48 faces the inner peripheral surfaces of the support member 53, the first accommodating member 55, and the second accommodating member 56.

Further, in the circuit built-in member 57 located on the rear end side of the fifth structure, the small diameter portion 921 and the medium diameter portion 922 of the sealing portion 92 are accommodated in the second accommodating member 56, while the large diameter is the rear end side. The diameter portion 923 projects outward (to the rear end side) from the rear end of the second storage member 56.

Here, the procedure for attaching the circuit built-in member 57 to the second housing member 56 will be described more specifically.
When inserting the fifth structure into the fourth structure, the circuit built-in member 57 is inserted or pushed into the second housing member 56 from the rear end side with the small diameter portion 921 as the front end side. At this time, the circuit built-in member 57 is housed inside the second rear end 563 of the second housing member 56 in this order of the small diameter portion 921 and the medium diameter portion 922. Further, the input ground plate 94 attached to the outer peripheral surface of the medium diameter portion 922 of the circuit built-in member 57 is also housed inside the second rear end portion 563 together with the medium diameter portion 922.

The outer peripheral surface of the holding member 48, which constitutes the fifth structure together with the circuit-embedded member 57, abuts the inner peripheral surface of the second accommodating member 56 as described above, so that the circuit is incorporated in the second accommodating member 56. The member 57 cannot be pushed in anymore. At this time, the small diameter portion 921 and the medium diameter portion 922 (including the input ground plate 94) of the circuit built-in member 57 are accommodated inside the second rear end portion 563 of the second accommodation member 56, while the large diameter portion 923 is accommodated. Pops out to the outside (rear end side) of the rear end of the second rear end portion 563. However, the rearmost ends of the middle-diameter portion 922 and the main body 943 may slightly project outside (rear end side) of the rear end of the second rear end portion 563.

When the circuit built-in member 57 is inserted into the second housing member 56, the main body portion 943 of the input grounding plate 94 has the surface first projection 924a provided on the surface 922a of the intermediate diameter portion 922 located behind the main body portion 943. The surface second projection 924b is smoothly guided by the shape (the inclined surface on each tip side and the flat surface on the rear end side). Further, when the circuit built-in member 57 is inserted into the second housing member 56, the back surface first protrusion 925a and the back surface second protrusion 925b provided on the back surface 922b of the intermediate diameter portion 922 also have the same shape (each tip side). The inclined surface and the flat surface on the rear end side make it difficult to prevent the insertion of the circuit built-in member 57.

Further, when the circuit built-in member 57 is inserted into the second accommodating member 56, the input ground plate 94 having the F-shape is pulled to the rear end side by the friction with the second accommodating member 56. At this time, the rear end of the main body portion 943 provided on the input ground plate 94 hits a step formed between the medium diameter portion 922 and the large diameter portion 923, and is prevented from being pulled further toward the rear end side. Is becoming The second surface projection 924b provided on the medium diameter portion 922 is a rear end of the main body portion 943 provided on the input ground plate 94 with respect to the step formed between the medium diameter portion 922 and the large diameter portion 923. Assists in hitting. As a result, when the circuit built-in member 57 is inserted into the second accommodating member 56, the main body portion 913 of the input ground plate 94 is twisted due to contact with the inner peripheral surface of the second accommodating member 56, and the first protruding portion is formed. The input ground plate 94 is prevented from being cut by the 941 and the second protruding portion 942.

When the input ground plate 94 that constitutes the circuit built-in member 57 is accommodated in the second rear end portion 563 of the second accommodating member 56, the surface projection group 924 provided on the surface 922a of the intermediate diameter portion 922 is The body portion 943 of the ground plate 94 is pushed toward the inner peripheral surface of the second rear end portion 563 of the second accommodating member 56. At this time, the back surface projection group 925 provided directly on the back surface of the front surface projection group 924, that is, on the back surface 922b, butts against the inner peripheral surface of the second rear end portion 563 of the second accommodating member 56. It assists the pressing of the main body portion 943 against the inner peripheral surface of the second rear end portion 563 of the second housing member 56. Further, the first projecting portion 941 and the second projecting portion 942, which constitute the input grounding plate 94 together with the main body portion 943, function as the leaf springs themselves, so that the main body portion 943 is separated from the second housing member 56 by the second portion. Push toward the inner peripheral surface of the rear end portion 563. Furthermore, the size of the outer diameter of the middle diameter portion 922, in which the thickness of the main body portion 943 of the input grounding plate 94 is added to the outer diameter from the front surface first projection 924a to the back surface first projection 925a, is the second accommodating member 56. Is slightly larger than the inner diameter of the inner peripheral surface of the second rear end portion 563. Therefore, the outer peripheral surface of the main body portion 943 of the input ground plate 94 provided in the circuit built-in member 57 is pressed against the inner peripheral surface of the second rear end portion 563 of the second accommodating member 56 with a certain pressure. You will be in contact with each other.

Further, the main body portion 943 provided on the input grounding plate 94 with the medium diameter portion 922 and the input grounding plate 94 accommodated inside the second rear end portion 563 of the second housing member 56. Faces the round hole 566 provided in the second rear end portion 563. That is, the round hole 566 provided in the second rear end portion 563 of the second housing member 56 and the main body portion 943 provided in the input ground plate 94 of the circuit built-in member 57 are made to overlap each other. In other words, the main body portion 943 provided on the input ground plate 94 of the circuit built-in member 57 is made visible through the round hole 566 provided at the second rear end portion 563 of the second housing member 56. At this time, the flat surface of the first surface projection 924a provided on the surface 922a of the intermediate diameter portion 922 is located behind the portion of the main body portion 943 seen from the round hole 566. Further, behind the flat surface of the front surface first projection 924a, the flat surface of the back surface first projection 925a provided on the back surface 922b of the intermediate diameter portion 922 is located. As a result, a portion of the main body portion 943 visible through the round hole 566 is subjected to a larger pressure than a portion not visible through the round hole 566, and the inner peripheral surface of the second rear end portion 563 of the second accommodation member 56. Will be pressed against.

Then, in this state, at the site where the round hole 566 is formed, the second rear end portion 563 of the second accommodating member 56 (more specifically, the inner peripheral surface of the round hole 566) is formed through the round hole 566. The sixth structure is obtained by soldering the main body 943 of the input ground plate 94. At this time, when the input grounding plate 94 is pushed by the soldering iron or the like, the surface first projection 924a provided on the medium diameter portion 922 of the circuit built-in member 57 has the input grounding plate 94 at the back side (sealing portion). It is prevented from hindering the soldering by pulling it toward the (92 side). In addition, in the case where the rearmost end of the main body 943 of the input ground plate 94 slightly protrudes to the outside (rear end side) of the rear end of the second rear end 563 of the second accommodating member 56. In this portion, the second housing member 56 and the main body portion 943 of the input ground plate 94 may be further soldered. Here, the reason why the second housing member 56 and the input ground plate 94 of the circuit built-in member 57 are joined (soldered) is that the mounting target of the pressure detection device 20 vibrates with the operation of the internal combustion engine 10 It is due to being.

(Assembly of seventh structure)
Next, the intermediate outer casing 33 is inserted into the front outer casing 31 of the sixth structure from the rear end side. At this time, the front end side surface of the intermediate outer casing 33 abuts on the rear end side surface of the front end external casing 31. Then, the seventh structure is obtained by performing laser welding on the boundary between the tip outer casing 31 and the intermediate outer casing 33 over the entire circumference.

(Assembly of Eighth Structure)
Although detailed description is omitted here, connection of the rear end external housing 34, the connection member 58, the closing member 59, the second seal member 72, the connection cable 80 (power supply line 81, signal line 82, and ground line 83) and Assembly is performed to obtain an eighth structure.

(Assembly of ninth structure)
The ninth structure is obtained by inserting the eighth structure from the rear end side into the intermediate outer casing 33 of the seventh structure. At this time, the rear end side of the intermediate outer casing 33 is accommodated in the front end side of the rear end outer casing 34. At this time, the power receiving plate 95 provided in the circuit-embedded member 57 is inserted into the terminal connected to the power supply line 81 in the connection member 58, and the terminal connected to the signal line 82 in the connection member 58. The output signal plate 96 provided in the circuit built-in member 57 is inserted, and the output ground plate 97 provided in the circuit built-in member 57 is inserted in the terminal connected to the ground wire 83 in the connection member 58. ..

(Assembly of pressure detection device)
Finally, the first seal member 71 is inserted into the tip external housing 31 of the ninth structure from the tip side. At this time, the surface on the rear end side of the first seal member 71 abuts on the surface on the front end side of the stepped portion provided on the rear end side of the front external housing 31. As a result, the inner peripheral surface of the first seal member 71 faces the outer peripheral surface of the tip outer casing 31.
As described above, the pressure detection device 20 integrated with the connection cable 80 is obtained.

[Pressure detection operation by pressure detection device]
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 32a of the diaphragm head 32. In the diaphragm head 32, the pressure received by the pressure receiving surface 32a is transmitted to the back-side center convex portion 32d on the back side, and further transmitted from the back-side center convex portion 32d to the tip electrode member 42 via the tip insulating member 43. 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 rear end electrode member 44, and the piezoelectric element 41 generates an electric charge according to the received pressure. The charge generated in the piezoelectric element 41 is supplied as a charge signal to the input signal terminal 91a and the input ground terminal 91b of the circuit board 91 via the positive path and the negative path. The electric charge signal supplied to the circuit board 91 is subjected to various kinds of processing in the processing circuit 912 mounted on the circuit board 91 to be an output signal. Then, the output signal output from the output signal terminal 91d of the circuit board 91 is transmitted to the control device 100 via the connection member 58 and the connection cable 80.

[Effects of this Embodiment]
In the pressure detection device 20 of the present embodiment, the circuit built-in member 57 in which the circuit board 91 having the processing circuit 912 connected to the positive electrode side of the piezoelectric element 41 is built in and sealed in the sealing portion 92. Was used. Further, an input ground plate 94 for connecting to the negative electrode side of the piezoelectric element 41 is provided on the side surface of the sealing portion 92 in the circuit built-in member 57. Then, as the circuit built-in member 57 is inserted into the cylindrical second housing member 56 connected to the negative electrode side of the piezoelectric element 41, the circuit built-in member 57 is formed on the inner peripheral surface of the second housing member 56. The input ground plate 94 provided on the outer peripheral surface is made to abut. Thereby, even when a shock is applied to the pressure detection device 20 from the outside, for example, the separation between the second housing member 56 and the input ground plate 94 can be suppressed. Therefore, the reliability of the electrical connection between the piezoelectric element 41 and the processing circuit 912 in the pressure detection device 20 can be improved.

Further, in the present embodiment, the input ground plate 94 is connected to the first protruding portion 941 and the second protruding portion 942 protruding from the side surface of the sealing portion 92, and the first protruding portion 941 and the second protruding portion 942. And a main body portion 943. Then, the first protruding portion 941 and the second protruding portion 942 are bent along the outer peripheral surface of the sealing portion 92. As a result, the first projecting portion 941 and the second projecting portion 942 function as a leaf spring, so that the inner circumference of the second accommodating member 56 is different from the case where the input ground plate 94 does not have the function of a leaf spring. The main body 943 of the input ground plate 94 can be abutted against the surface with a larger pressing force.

Further, in the present embodiment, the surface projection group 924 (the first surface projection 924a and the second surface projection 924b) protruding laterally is provided on the back surface side of the input ground plate 94 in the sealing portion 92. As a result, compared to the case where the surface projection group 924 is not provided, the main body portion 943 of the input grounding plate 94 can be pressed against the inner peripheral surface of the second accommodating member 56 with a greater pressing force. ..

Further, in the present embodiment, the back surface projection group 925 (back surface first projection 925a and back surface second projection 925b) that protrudes laterally is provided on the back side of the front surface projection group 924 in the sealing portion 92. As a result, it becomes possible to abut the main body portion 943 of the input ground plate 94 against the inner peripheral surface of the second accommodating member 56 with a greater pressing force, as compared with the case where the rear surface projection group 925 is not provided. ..

In addition, in the present embodiment, a round hole 566 is provided on the side surface of the second housing member 56 that houses the circuit built-in member 57, and the input ground plate provided in the circuit built-in member 57 is provided at the position where the round hole 566 is formed. The main body 943 of 94 is arranged. Then, the second accommodating member 56 and the main body portion 943 of the input ground plate 94 are joined by soldering through the round hole 566 provided in the second accommodating member 56. As a result, as compared with the case where the second housing member 56 and the input ground plate 94 are not soldered, the joint strength between them can be increased, and the second housing member 56 and the input ground plate when receiving an impact from the outside. The separation from 94 can be suppressed further.

Further, in the present embodiment, the piezoelectric element 41 and the processing circuit 912 provided on the circuit board 91 are provided inside the second housing member 56 and the first housing member 55 connected to the second housing member 56. The conductive member 47 is used for connection. Then, in the pressure detection device 20, the housing portion 30 that accommodates the first housing member 55 and the second housing member 56 inside and is electrically insulated from the first housing member 55 and the second housing member 56 is provided. Provided. Thereby, for example, when the pressure detection device 20 is attached to the internal combustion engine 10, various noises that enter the housing portion 30 (the housing path) from the internal combustion engine 10 may cause an electric path (positive path) of the piezoelectric element 41. And negative path) can be suppressed.

[Other]
In the present embodiment, the second housing member 56 and the main body portion 943 provided on the input ground plate 94 of the circuit-embedded member 57 are joined by soldering, but the present invention is not limited to this. Alternatively, a joining method such as laser welding may be used.

Further, in the present embodiment, the negative route and the case route are separated, but the present invention is not limited to this, and the case route may function as the negative route. In this case, for example, the diaphragm head 32 and the tip electrode member 42 are brought into direct contact with each other, and the outer peripheral surface of the input ground plate 94 provided in the circuit built-in member 57 is provided on the inner peripheral surface of the intermediate outer casing 33. Just hit them. In this case, for example, the first housing member 55 and the second housing member 56 are unnecessary.

DESCRIPTION OF SYMBOLS 1... Pressure detection system, 10... Internal combustion engine, 20... Pressure detection device, 30... Housing part, 31... Tip external housing, 32... Diaphragm head, 33... Intermediate external housing, 34... Rear end external housing, 35... 1st internal housing, 36... 2nd internal housing, 40... Detection mechanism part, 41... Piezoelectric element, 42... Tip electrode member, 43... Tip insulating member, 44... Rear end electrode member, 45... Rear end Insulating member, 46... First coil spring, 47... Conducting member, 48... Holding member, 49... Pressurizing member, 50... Insulating pipe, 51... First insulating member, 52... Second insulating member, 53... Supporting member, 54 ...Second coil spring, 55...first accommodating member, 56...second accommodating member, 57...circuit built-in member, 58...connecting member, 59...blocking member, 60...third insulating member, 70...seal portion, 80...connection Cable, 91... Circuit board, 92... Sealing part, 93... Input signal plate, 94... Input ground plate, 95... Power receiving plate, 96... Output signal plate, 97... Output ground plate, 100... Control device

[Holding member]
The holding member 48 is a member having a hollow structure and having a tubular shape as a whole. The holding member 48 is made of an insulating synthetic resin material such as PPT (Polypropylene Terephthalate). The holding member 48 has a tip portion located closest to the tip end side, an intermediate portion located at the rear end side of the tip portion, and a rear end portion located at the rear end side of the intermediate portion. The outer diameter of the holding member 48 increases in the order of the front end portion, the intermediate portion, and the rear end portion. The holding member 48 is arranged so as to straddle the inside of the tip outer casing 31 and the inside of the intermediate outer casing 33. The conductive member 47 is housed and held inside the holding member 48. More specifically, the holding member 48 houses the rear end side of the conductive member 47, that is, the rear end side of the rear end rod-shaped portion 473. As a result, of the conductive member 47, the tip rod portion 471 and the intermediate rod portion 472 and the tip end side of the trailing end rod portion 473 project to the tip end side of the holding member 48. On the other hand, the rear end of the holding member 48 is formed with a concave portion extending from the rear end side toward the front end side. The inner diameter of the hole provided in the holding member 48 is slightly larger than the outer diameter of the rear rod portion 473 in the conduction member 47, the holding member 48 and the conductive member 47, press-fitting (clearance fit ) Are integrated.

[Second insulating member]
The second insulating member 52 is a ring-shaped member as a whole. Like the first insulating member 51, the second insulating member 52 is made of a ceramic material such as alumina that has insulating properties and high heat resistance. The second insulating member 52 is arranged inside the tip outer casing 31, inside the first inner casing 35, and outside the pressing member 49. The second insulating member 52 is arranged on the rear end side of the first insulating member 51. The front surface of the second insulating member 52 contacts the rear surface of the third step portion 497 of the pressing member 49, and the rear surface of the second insulating member 52 is the second internal portion. The housing 36 comes into contact with the surface of the second tip tubular portion 361 on the tip side. The outer diameter of the second insulating member 52 is smaller than the inner diameter of the first inner casing 35 on the rear end side of the first inner step 354. Further, the inner diameter of the second insulating member 52 is larger than the outer diameter of the fourth tubular portion 494 of the pressure member 49. In addition, in the present embodiment, the second insulating member 52 having the same size as the first insulating member 51 is used.

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

Claims (13)

A piezoelectric element that outputs an electric signal according to the pressure received from the outside,
An accommodating member having conductivity, to which one end of the piezoelectric element is connected,
A processing circuit to which the other end of the piezoelectric element is connected and which processes the electric signal; a sealing portion which has an insulating property and seals the processing circuit; and a processing circuit which has conductivity and one of which is the processing circuit. A pressure including a conductive part exposed to the outside of the side surface of the sealing part while being connected to the other, and the conductive part is housed in the housing member and the conductive part abuts against the housing member. Detection device. The pressure detecting device according to claim 1, wherein the conductive portion of the circuit-embedded member is composed of a leaf spring having a restoring force from the side surface of the sealing portion toward the housing member. The said sealing part in the said circuit built-in member is provided behind the said electroconductive part, and has a protrusion which protrudes toward the said accommodating member from the said side surface of the said sealing part, The Claim 1 or 2 characterized by the above-mentioned. Pressure detector. The sealing portion in the circuit-embedded member is provided on the back side of the protrusion in the sealing portion, and further has another protrusion protruding from the side surface of the sealing portion toward the housing member. The pressure detection device according to claim 3. The accommodation member is provided with a hole penetrating the inner surface and the outer surface of the accommodation member, and the conductive portion provided in the circuit-embedded member is disposed in the formation portion of the hole, and the formation portion of the hole is formed. The pressure detecting device according to any one of claims 1 to 4, wherein the housing member and the conductive portion are joined together. The piezoelectric element is housed inside the housing member,
Having a conductive property and being housed inside the housing member, and further connected to the piezoelectric element and the processing circuit, further having a conductive member for conducting the electric signal to the processing circuit,
One pole side of the piezoelectric element is connected to the conductive member,
The pressure detecting device according to claim 1, wherein the other pole side of the piezoelectric element is connected to the housing member. 7. The pressure detecting device according to claim 6, further comprising a housing portion that houses the housing member and is electrically insulated from the housing member. A processing circuit that is connected to one end of a piezoelectric element that outputs an electric signal according to the pressure received from the outside and that processes the electric signal,
A sealing portion having an insulating property and sealing the processing circuit;
A circuit built-in member having conductivity and one of which is connected to the processing circuit and the other of which is exposed on a side surface of the sealing portion. A processing circuit for processing an electric signal supplied from one pole side of the piezoelectric element, a sealing portion having an insulating property and sealing the processing circuit, and a processing circuit having conductivity and one of which is the processing circuit. And a step of preparing a circuit-embedded member having a conductive portion that is connected to the other and is exposed to the outside of the side surface of the sealing portion,
A method of manufacturing a pressure detecting device, comprising the step of accommodating the circuit-embedded member in an accommodating member that is electrically conductive and is connected to the other pole side of the piezoelectric element. 10. The method for manufacturing a pressure detecting device according to claim 9, wherein the conductive portion of the circuit built-in member is formed of a leaf spring having a restoring force from the side surface of the sealing portion toward the housing member. .. The said sealing part in the said circuit built-in member is provided behind the said electroconductive part, and has a protrusion which protrudes toward the said accommodating member from the said side surface of the said sealing part, The claim 9 or 10 characterized by the above-mentioned. Manufacturing method of the pressure detecting device. The sealing portion in the circuit-embedded member is provided on the back side of the protrusion in the sealing portion, and further has another protrusion protruding from the side surface of the sealing portion toward the housing member. The method for manufacturing a pressure detecting device according to claim 11. The accommodating member is provided with a hole that penetrates the inner surface and the outer surface of the accommodating member, and the conductive portion provided in the circuit-embedded member is disposed at a portion where the hole is formed.
13. The method according to claim 9, further comprising the step of, after accommodating the circuit built-in member in the accommodating member, joining the accommodating member and the conductive portion at a portion where the hole is formed. A method for manufacturing the pressure detection device described.