JP6948491B1 - Pressure detector, circuit built-in member - Google Patents

Abstract

The circuit built-in member 46 provided in the pressure detection device that detects the combustion pressure of the internal combustion engine has a processing circuit that processes the charge signal output by the piezoelectric element and a seal that has insulation and seals the processing circuit. One of the stop portion 60 is connected to the processing circuit, and the other is provided at the rear end of the sealing portion 60 and protrudes from the rear end side second sealing portion 623 provided on the side portion of the sealing portion 60. It has an input ground electrode 72 and the like that are bent toward the rear end side back surface 62e. Of the input ground electrode 72, the disc spring portion 724 arranged on the rear end side back surface 62e has a curved portion 7241 having a C shape and a bumping portion 7242 bent from the curved portion 7241 to the rear end side. The abutment portion 7242 is pressed toward the front end side by the rear end outer housing.

Description

The present invention relates to a pressure detection device and a member having a built-in circuit.

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 by these detection devices, a control device called an ECU (Engine Control Unit) controls the operation of the internal combustion engine and the like.

Patent Document 1 has conductivity and a piezoelectric element that detects a change in pressure and a circuit board that is connected to the positive electrode side of the piezoelectric element and is provided with a processing circuit that processes the output signal of the piezoelectric element. Moreover, the accommodating member arranged so as to cover the circuit board, connected to the negative electrode side of the piezoelectric element, and connected to the ground of the processing circuit via the ground plate provided on the circuit board side, the piezoelectric element, the circuit board, and the accommodating member. Described is a pressure detector that houses the accommodating member and includes a detection element, a circuit board, and a housing that is electrically insulated from the accommodating member.

Japanese Unexamined Patent Publication No. 2017-173122

Here, if a configuration is adopted in which the accommodating member and the grounding plate provided on the circuit board side are simply brought into contact with each other, the contact state between the accommodating member and the accommodating member may become unstable, and the contact state between the accommodating member and the accommodating member may become unstable. There was a risk that the high frequency characteristics of the output signal would vary.
An object of the present invention is to suppress variations in high-frequency electrical characteristics at the output of a processing circuit that processes an electrical signal from a piezoelectric element.

The pressure detection device of the present invention includes a piezoelectric element that outputs an electric signal corresponding to a pressure received from the outside, a processing circuit that processes the electric signal input from the piezoelectric element, and one end side close to the piezoelectric element. A sealing portion extending from the piezoelectric element along the axial direction toward the other end side, which has insulation and seals the processing circuit, and a conductive portion which has conductivity and one of which is connected to the processing circuit. A circuit-embedded member having a ground electrode having the other exposed to the outside of the sealing portion, and the other end of the piezoelectric element extending along the axial direction and having conductivity as well as being connected to the above. The ground electrode provided in the circuit built-in member, including a housing member for accommodating the circuit built-in member, is provided on the back surface of the sealing portion which has a spring property and is located on the other end side of the sealing portion. The accommodating member is characterized in that it comes into contact with the ground electrode provided on the back surface of the sealing portion and applies a pressing force toward the one end side.
In such a pressure detection device, the circuit built-in member has conductivity, one of which is connected to the processing circuit and the other of which is exposed to the outside of the sealing portion, and an input to which the electric signal is input. A signal electrode may be further included, and the input signal electrode may project from one end side of the sealing portion to the outside of the sealing portion.
Further, the circuit built-in member has conductivity, one of which is connected to the processing circuit and the other of which is exposed to the outside of the sealing portion to receive a power source for operating the processing circuit. And has conductivity, one is connected to the processing circuit and the other is exposed to the outside of the sealing portion, and has conductivity with an output signal electrode that outputs an output signal from the processing circuit. Further, one is connected to the processing circuit and the other further includes another ground electrode exposed to the outside of the sealing portion, and the power receiving electrode, the output signal electrode and the other ground electrode are sealed. The ground electrode may be arranged so as to project outward from the back surface of the portion and surround the power receiving electrode, the output signal electrode, and the other ground electrode on the back surface.
Further, the ground electrode may be provided on the back surface of the sealing portion by projecting from the side surface of the sealing portion to the outside of the sealing portion and bending the ground electrode.
From another point of view, the pressure detection device of the present invention has a piezoelectric element that outputs an electric signal corresponding to the pressure received from the outside and a processing circuit that processes the electric signal input from the piezoelectric element. And a sealing portion that extends along the axial direction from one end side close to the piezoelectric element toward the other end side far from the piezoelectric element, has insulating properties, and seals the processing circuit, and has conductivity. And one is connected to the processing circuit and the other is exposed to the outside of the sealing portion, and one is conductive and one is connected to the processing circuit and the other is the outside of the sealing portion. A power receiving electrode that is exposed to and receives power to operate the processing circuit, and one that is conductive and is connected to the processing circuit and the other that is exposed to the outside of the sealing portion, and the processing Built-in circuit having an output signal electrode that outputs an output signal from the circuit and another ground electrode that is conductive and one is connected to the processing circuit and the other is exposed to the outside of the sealing portion. The power receiving electrode, the output signal electrode, and the other ground electrode, including the member, are provided so as to project outward from the back surface of the sealing portion located on the other end side of the sealing portion. The ground electrode is provided on the back surface of the sealing portion, and is characterized in that it is arranged so as to surround the power receiving electrode, the output signal electrode, and the other ground electrode.
In such a pressure detecting device, the ground electrode is provided on the back surface of the sealing portion by projecting from the side surface of the sealing portion to the outside of the sealing portion and bending the ground electrode. , C-shaped may be exhibited on the back surface.
Further, the input signal electrode is conductive and has an input signal electrode in which one is connected to the processing circuit and the other is exposed to the outside of the sealing portion and the electric signal is input. It is not necessary that the sealing portion protrudes from one end side to the outside of the sealing portion and is not surrounded by the ground electrode.
From another point of view, the circuit-embedded member of the present invention includes a processing circuit that processes an electric signal input from a piezoelectric element that outputs an electric signal corresponding to a pressure received from the outside, and the piezoelectric element. A sealing portion that extends along the axial direction from one end side close to the piezoelectric element toward the other end side far from the piezoelectric element, has insulation and seals the processing circuit, and has conductivity and one of the treatments. The sealing electrode is connected to a circuit and the other side is exposed to the outside of the sealing portion, and the grounding electrode has a spring property and is located on the other end side of the sealing portion. The feature is that it is provided on the back surface of the part.
From another point of view, the circuit-embedded member of the present invention includes a processing circuit that processes an electric signal input from a piezoelectric element that outputs an electric signal corresponding to a pressure received from the outside, and the piezoelectric element. A sealing portion extending along the axial direction from one end side close to the electrode to the other end side far from the piezoelectric element and having insulation and sealing the processing circuit, and a sealing portion having conductivity and one of which is the processing. A ground electrode that is connected to the circuit and the other is exposed to the outside of the sealing portion, and one that is conductive and is connected to the processing circuit and the other is exposed to the outside of the sealing portion. A power receiving electrode that receives power to operate the processing circuit, and one that is conductive and is connected to the processing circuit and the other that is exposed to the outside of the sealing portion, and an output signal from the processing circuit. The power receiving electrode, the output, which has an output signal electrode for outputting the above, and another ground electrode which is conductive and one of which is connected to the processing circuit and the other is exposed to the outside of the sealing portion. The signal electrode and the other ground electrode are provided so as to project outward from the back surface of the sealing portion located on the other end side of the sealing portion, and the ground electrode is formed on the sealing portion. It is characterized in that it is provided on the back surface and is arranged so as to surround the power receiving electrode, the output signal electrode, and the other ground electrode.

According to the present invention, it is possible to suppress variations in high-frequency electrical characteristics at the output of a processing circuit that processes an electric signal from a piezoelectric element.

It is a schematic block diagram of the pressure detection system which concerns on embodiment. It is a side view of the pressure detection device. It is sectional drawing (III-III sectional view of FIG. 2) of the pressure detection apparatus. It is an enlarged cross-sectional view of the tip side (IV region of FIG. 3) of a pressure detection device. (A) is a perspective view of a circuit built-in member provided in the pressure detection device, and (b) is a side view of the circuit built-in member. It is a schematic block diagram of the circuit board provided in the circuit built-in member. (A) is a side view of the circuit built-in member before the metal plate is bent, and (b) is a side view of the circuit built-in member.

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

Here, the internal combustion engine 10 whose pressure is to be detected includes a cylinder block 11 in which a cylinder is formed, a piston 12 that reciprocates in the cylinder, and a combustion chamber C that is fastened to the cylinder block 11 together with the piston 12 and the like. It has a cylinder head 13 constituting the above. Further, the cylinder head 13 is provided with a communication hole 13a that communicates the combustion chamber C with the outside. An internal screw (not shown) is provided inside the communication hole 13a. Then, the pressure detecting device 20 is attached to the internal combustion engine 10 by inserting the tip end side of the pressure detecting device 20 into the communication hole 13a and fixing the pressure detecting device 20 to the cylinder head 13. More specifically, the pressure detection device 20 is attached by screwing the male screw provided on the tip side of the pressure detection device 20 into the female screw provided in the communication hole 13a. Here, the cylinder block 11, the piston 12, and the cylinder head 13 constituting the internal combustion engine 10 are made of a conductive metal material such as cast iron or aluminum.

[Configuration of pressure detector]
FIG. 2 is a side view of the pressure detecting device. Further, FIG. 3 is a cross-sectional view of the pressure detection device 20 (a cross-sectional view taken along line III-III of FIG. 2). Further, FIG. 4 is an enlarged cross-sectional view of the tip end side (IV region of FIG. 3) of the pressure detection device 20.

The pressure detecting device 20 includes a housing portion 30 which has a cylindrical shape as a whole and is provided so as to be exposed to the outside, and various mechanisms for detecting pressure, and almost the entire pressure detecting device 20 is housed inside the housing portion 30. It also has a detection mechanism unit 40 which is provided so as to be partially exposed to the outside and to which the connection cable 80 is connected. Then, in the pressure detecting device 20, the left side in FIG. 2 faces the combustion chamber C (lower side in FIG. 1) and the right side in FIG. 2 faces the outside (upper side in FIG. 1) with respect to the internal combustion engine 10 shown in FIG. It is installed so that it faces. In the following description, in FIG. 2, the side toward the left in the figure is referred to as the “tip side” of the pressure detection device 20, and the side toward the right in the figure is referred to as the “rear end side” of the pressure detection device 20. Further, in the following description, the direction of the center line of the pressure detecting device 20 shown by the alternate long and short dash line in FIG. 2 and the like is simply referred to as “center line direction”. Here, in the present embodiment, the "center line direction" is an example of the axial direction, the "tip side" is an example of one end side, and the "rear end side" is an example of the other end side.

(Structure of housing)
The housing portion 30 includes a tip outer housing 31 and a diaphragm head 32 attached to the tip side of the tip outer housing 31. Further, the housing portion 30 includes a first inner housing 33 inside the tip outer housing 31 and attached to the rear end side of the diaphragm head 32, and the tip outer housing 31 and the first inner housing 33. It is provided with a second internal housing 34 which is inside and is attached to the rear end side of the diaphragm head 32. Further, the housing portion 30 includes a rear end outer housing 35 attached to the rear end side of the front end outer housing 31. In the housing portion 30, the front end outer housing 31, the diaphragm head 32, and the rear end outer housing 35 are exposed to the outside. On the other hand, the first inner housing 33 and the second inner housing 34 are not exposed to the outside and are housed inside the tip outer housing 31.

[External tip housing]
The tip outer housing 31 is a member having a hollow structure and having a cylindrical shape as a whole. The tip outer housing 31 is made of a metal material such as stainless steel, which has conductivity and high heat resistance and acid resistance. Further, the tip outer housing 31 has a small diameter portion 31a having the smallest outer diameter, a large diameter portion 31b having the largest outer diameter, and a medium diameter having an outer diameter intermediate between them from the front end side to the rear end side. It has a part 31c. A male screw 31d is provided on the outer peripheral surface of the tip outer housing 31 on the tip side of the small diameter portion 31a.

[Diaphragm head]
The diaphragm head 32 is a member having a disk shape as a whole. The diaphragm head 32 is made of a metal material such as stainless steel, which has conductivity and high heat resistance and acid resistance. The diaphragm head 32 is provided so as to close the opening on the tip side of the tip outer housing 31. The boundary between the diaphragm head 32 and the tip outer housing 31 is laser-welded over the entire circumference.

[First internal housing]
The first internal housing 33 is a member having a hollow structure and having a cylindrical shape as a whole. The first internal housing 33 is made of a metal material such as stainless steel, which has both conductivity and high heat resistance. The first inner housing 33 is provided so that the entire first inner housing 33 is housed inside the tip outer housing 31 and a part of the tip side of the first inner housing 33 abuts on a part of the rear end side of the diaphragm head 32. The boundary between the first internal housing 33 and the diaphragm head 32 is laser welded over the entire circumference.

[Second internal housing]
The second internal housing 34 is a member having a hollow structure and having a cylindrical shape as a whole. The second internal housing 34 is made of a metal material such as stainless steel, which has both conductivity and high heat resistance. The second inner housing 34 is provided so that the entire second inner housing 34 is housed inside the tip outer housing 31 and almost the entire area except the rear end side is housed inside the first inner housing 33. .. The boundary between the second inner housing 34 and the first inner housing 33 is laser-welded over the entire circumference.

[Rear end external housing]
The rear end outer housing 35 as an example of the accommodating member is a member having a hollow structure and having a cylindrical shape as a whole. The rear end outer housing 35 is made of a metal material such as stainless steel, which has conductivity and high heat resistance and acid resistance. Further, the rear end outer housing 35 has a first cylindrical portion 35a, a second tubular portion 35b, a third tubular portion 35c, and a fourth tubular portion 35d from the front end side to the rear end side. And a fifth cylindrical portion 35e. Here, the outer diameters of the first cylindrical portion 35a, the second tubular portion 35b, the third tubular portion 35c, and the fourth tubular portion 35d become smaller in this order. On the other hand, the fifth cylindrical portion 35e has a larger outer diameter than the adjacent fourth tubular portion 35d, and is substantially the same as the third tubular portion 35c. Further, in the rear end outer housing 35, the inside of the front end side is the first inner diameter portion 35f, and the inside of the rear end side is the second inner diameter portion 35g. Here, the inner diameter of the second inner diameter portion 35g is smaller than that of the first inner diameter portion 35f, and an inner step portion 35h is provided at the boundary between the first inner diameter portion 35f and the second inner diameter portion 35g. .. The front end side of the first cylindrical portion 35a in the rear end outer housing 35 is provided so as to abut on the rear end side of the large diameter portion 31b in the front end outer housing 31. The boundary between the rear end outer housing 35 and the front end outer housing 31 is laser welded over the entire circumference.

It should be noted that each of the above-mentioned welded parts does not necessarily have to be formed over the entire circumference thereof, and may be formed by spot welding in which a plurality of laser spots are formed.

(Configuration of detection mechanism)
The detection mechanism unit 40 includes a piezoelectric element 41, a tip electrode member 42, a rear end electrode member 43, an insulating member 44, a coil spring 45, a circuit built-in member 46, a connecting member 47, and a closing member 48. I have.

〔Piezoelectric element〕
The piezoelectric element 41 is a member that exhibits a columnar shape as a whole. The piezoelectric element 41 includes a piezoelectric body that exhibits a piezoelectric action of a piezoelectric vertical effect. The piezoelectric element 41 is arranged inside the tip outer housing 31 (and the first inner housing 33).

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

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

[Tip electrode member]
The tip electrode member 42 is a member that exhibits a columnar shape as a whole. The tip electrode member 42 is made of a metal material such as stainless steel, which has both conductivity and high heat resistance. The tip electrode member 42 is arranged inside the tip outer housing 31 (first inner housing 33) and on the tip side of the piezoelectric element 41, and the surface on the rear end side of the tip electrode member 42 is the piezoelectric element 41. It comes into contact with the surface on the tip side. Further, the surface of the tip electrode member 42 on the front end side is in contact with the surface of the convex portion protruding from the central portion of the diaphragm head 32 toward the rear end side. The outer diameter of the tip electrode member 42 is larger than the outer diameter of the piezoelectric element 41.

[Rear end electrode member]
The rear end electrode member 43 is a member that exhibits a top shape as a whole. More specifically, the rear end electrode member 43 has a T-shaped cross section, and the outer diameter on the rear end side is smaller than the outer diameter on the front end side. The rear end electrode member 43 is made of a metal material such as stainless steel, which has both conductivity and high heat resistance. The rear end electrode member 43 is arranged inside the front end outer housing 31 (first inner housing 33), and the front end side surface of the rear end electrode member 43 is the rear end side surface of the piezoelectric element 41. It is designed to come into contact. Further, the outer diameter of the rear end electrode member 43 on the front end side is slightly larger than the outer diameter of the piezoelectric element 41, and the outer diameter of the rear end electrode member 43 on the rear end side is the outer diameter of the piezoelectric element 41. Is smaller than

[Insulation member]
The insulating member 44 is a member having a hollow structure and exhibiting an annular shape (cylindrical shape) as a whole. The insulating member 44 is made of a ceramic material such as alumina, which has insulating properties and high heat resistance. The insulating member 44 is arranged inside the front end outer housing 31 (first inner housing 33) and on the rear end side of the rear end electrode member 43, and the front end side surface of the insulating member 44 is the rear end electrode member. It comes into contact with the surface on the rear end side of the front end side of 43. Further, a convex portion provided on the rear end side of the rear end electrode member 43 is inserted into the tip end side of the through hole provided in the insulating member 44. Further, the surface on the rear end side of the insulating member 44 comes into contact with the surface on the front end side of the second inner housing 34. As a result, the front end electrode member 42, the piezoelectric element 41, the rear end electrode member 43, and the insulating member 44 are sandwiched and fixed by the diaphragm head 32 and the second internal housing 34 via the first internal housing 33. It has become so. At this time, it is desirable that a gap exists between the front end electrode member 42, the piezoelectric element 41, the rear end electrode member 43 and the insulating member 44, and the inner peripheral surface of the first inner housing 33.

[Coil spring]
The coil spring 45 is a member that exhibits a spiral shape as a whole, and expands and contracts in the center line direction. The coil spring 45 is made of a conductive metal material such as phosphor bronze. The coil spring 45 is arranged inside the tip outer housing 31 (first inner housing 33), straddling the inside of the insulating member 44 and the inside of the second inner housing 34. Therefore, the outer diameter of the coil spring 45 is smaller than the inner diameter of the through hole provided in the insulating member 44. The tip end side of the coil spring 45 is in contact with the rear end side surface of the rear end electrode member 43 inside the insulating member 44.

[Circuit built-in member]
The circuit built-in member 46 includes a circuit board 50 that processes an electric signal due to a weak electric charge output from the piezoelectric element 41, and a sealing portion 60 that seals the circuit board 50 by accommodating the circuit board 50 inside. I have. Further, the circuit built-in member 46 further includes an input signal electrode 71, an input ground electrode 72, a power receiving electrode 73, an output signal electrode 74, and an output ground electrode 75 that are electrically connected to the circuit board 50. Here, the input signal electrode 71 is provided on the front end side of the circuit board 50, and the input ground electrode 72, the power receiving electrode 73, the output signal electrode 74, and the output ground electrode 75 are on the rear end side of the circuit board 50. It is provided in. One end of each of the input signal electrodes 71 to 75 is sealed by the sealing portion 60 and connected to the circuit board 50, while the other end of each is covered by the sealing portion 60. It is exposed to the outside. The input signal electrodes 71 to 75 are each made of a conductive plate-shaped metal material.

The input signal electrode 71 has a base portion 711 extending along the center line direction and connected to the circuit board 50, and a protruding portion 712 protruding toward the tip end side of the base portion 711. Here, the width of the protruding portion 712 (the length in the direction intersecting the center line direction) is narrower than the width of the base portion 711 and smaller than the inner diameter of the coil spring 45. In the input signal electrode 71, the entire protruding portion 712 and the tip end side of the base portion 711 are exposed without being covered by the sealing portion 60. Then, this portion is inserted inside the second inner housing 34, and the rear end side of the coil spring 45 is wound around the protruding portion 712.

Although the details of the input ground electrode 72 will be described later, a part of the input ground electrode 72 has a disc spring shape, and a portion of the input ground electrode 72 having a disc spring shape is formed on an inner step portion 35h provided inside the rear end outer housing 35. It is designed to hit. The details of the circuit built-in member 46 will be described later.

[Connecting member]
The connecting member 47 is a member having a columnar shape as a whole. The connecting member 47 includes a base material made of a synthetic resin material such as PPS or PPT having insulation, and wiring and terminals made of a metal material such as copper having conductivity. The connecting member 47 is arranged inside the rear end outer housing 35. The rear end side of the circuit built-in member 46 faces the tip end side of the connection member 47, and the rear end sides of the power receiving electrode 73, the output signal electrode 74, and the output grounding electrode 75 provided in the circuit built-in member 46 face each other. It has been inserted.

[Blocking member]
The closing member 48 is a member having a columnar shape as a whole. However, the closing member 48 is formed with three through holes along the center line direction. The closing member 48 is made of an insulating rubber material. The front end side of the closing member 48 is arranged inside the rear end outer housing 35, and the rear end side protrudes outside the rear end of the rear end outer housing 35. The front end side of the closing member 48 faces the rear end side of the connecting member 47. Further, each electric wire (details will be described later) constituting the connection cable 80 is inserted into the three through holes provided in the closing member 48. The outer diameter of the closing member 48 is slightly larger than the inner diameter of the rear end side (second inner diameter portion 35g) of the rear end outer housing 35, and the rear end outer housing 35 and the closing member 48 are press-fitted. It is integrated by (tightening fit).

[Connection cable configuration]
The connection cable 80 includes a twisted power supply line 81, a signal line 82, and a ground wire 83, a covering member 84 that covers the outer circumferences of the power supply line 81, the signal line 82, and the ground wire 83, and a power supply line 81 and a signal line 82. And an inclusion 85 that fills the gap between the ground wire 83 and the covering member 84. The power supply line 81 is connected to the power receiving electrode 73, the signal line 82 is connected to the output signal electrode 74, and the grounding wire 83 is connected to the output grounding electrode 75 via the connecting member 47. Here, the power supply line 81, the signal line 82, and the ground wire 83 are each a conductor portion made of tin-plated annealed copper stranded wire, polyethylene (cross-linked polyethylene) or the like whose cross-linked structure is reinforced by using an electron wire or the like. It also has an insulating portion that covers and insulates the outer periphery of the conductor portion. Further, the covering member is made of a rubber material or a resin material having an insulating property. The connection cable 80 may be provided with a shield that shields the power supply line 81, the signal line 82, and the ground line 83, if necessary.

[Structure of circuit built-in member]
Next, the details of the circuit built-in member 46 described above will be described.
FIG. 5 is a diagram for explaining the configuration of the circuit built-in member 46 provided in the pressure detection device 20. More specifically, FIG. 5A is a perspective view of the circuit built-in member 46, and FIG. 5B is a side view of the circuit built-in member. Here, in FIG. 5A, the upper left side in the figure is the front end side, and the lower right side in the figure is the rear end side. Further, in FIG. 5B, the left side in the figure is the front end side, and the right side in the figure is the rear end side.

As described above, the circuit built-in member 46 includes a circuit board 50 and a sealing portion 60 (see FIG. 3). Further, the circuit built-in member 46 further includes an input signal electrode 71, an input ground electrode 72, a power receiving electrode 73, an output signal electrode 74, and an output ground electrode 75.

(Circuit board)
FIG. 6 is a schematic configuration diagram of a circuit board 50 provided on the circuit built-in member 46. However, FIG. 6 also shows the connection relationship between the circuit board 50 and the input signal electrodes 71 to 75. Hereinafter, the circuit board 50 will be described with reference to FIGS. 5 and 6.

The circuit board 50 is a member having a rectangular plate shape as a whole. The circuit board 50 has a printed wiring board 51 on which a wiring pattern for mounting various electronic components (circuit elements) is formed, and a processing circuit 52 mounted on the printed wiring board 51.

In this embodiment, a so-called glass epoxy board based on a glass cloth base epoxy resin is used as the printed wiring board 51. The printed wiring board 51 is provided with an input signal terminal 51a, an input grounding terminal 51b, a power receiving terminal 51c, an output signal terminal 51d, and an output grounding terminal 51e 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 51a via the input signal electrode 71, and the input ground terminal 51b is connected to the input ground terminal 51b via the input ground electrode 72. , The negative path (details will be described later) in the pressure detection device 20 is connected. On the other hand, the power supply line 81 is connected to the power receiving terminal 51c via the power receiving electrode 73, the signal line 82 is connected to the output signal terminal 51d via the output signal electrode 74, and the output ground terminal 51e is connected to the power line 82. , The ground wire 83 is connected via the output ground electrode 75. In the printed wiring board 51, the input ground terminal 51b and the output ground terminal 51e are internally connected.

Further, the processing circuit 52 includes an integrating circuit 52a that integrates the charge signal input from the piezoelectric element 41 via the input signal terminal 51a and converts it into a voltage signal, and an output signal terminal that amplifies the converted voltage signal. It has an amplifier circuit 52b that outputs to 51d. Here, an operational amplifier (not shown) is provided in each of the integrator circuit 52a and the amplifier circuit 52b, and a power supply voltage for operating them is supplied via the power receiving terminal 51c. Further, the ground of the integrator circuit 52a and the amplifier circuit 52b is connected to the input ground terminal 51b and the output ground terminal 51e. In this example, the processing circuit 52 is composed of a so-called integrated circuit (IC).

(Sealing part)
This time, the sealing portion 60 will be described mainly with reference to FIG.
The sealing portion 60 is a member having a columnar shape as a whole. The sealing portion 60 is made of a synthetic resin material such as epoxy having an insulating property. The sealing portion 60 includes a tip-side sealing portion 61 located relatively on the front-end side and a rear-end-side sealing portion 62 located on the rear-end side of the front-end-side sealing portion 61. The rear end side sealing portion 62 has a larger (thicker) outer diameter than the front end side sealing portion 61.

The tip-side sealing portion 61 has a tip-side first sealing portion 611, a tip-side second sealing portion 612, and a tip-side third sealing portion 613 in order from the tip side. In the present embodiment, the tip-side first sealing portion 611 to the tip-side third sealing portion 613 each have a polygonal appearance. Further, the tip-side first sealing portion 611 and the tip-side third sealing portion 613 have a larger outer diameter than the tip-side second sealing portion 612. Further, the outer diameters of the tip-side first sealing portion 611 and the tip-side third sealing portion 613 are substantially equal. In the following, the outer peripheral surface of the first sealing portion 611 on the tip side is referred to as the first side surface 61a on the tip side, and the outer peripheral surface of the second sealing portion 612 on the tip side is referred to as the second side surface 61b on the tip side. 3 The outer peripheral surface of the sealing portion 613 is referred to as a tip-side third side surface 61c. Further, the surface on the tip side of the first sealing portion 611 on the tip side is referred to as a front end side surface 61d.

The rear end side sealing portion 62 has a rear end side first sealing portion 621, a rear end side second sealing portion 622, and a rear end side third sealing portion 623 in this order from the front end side. There is. Here, the rear end side first sealing portion 621 is located on the rear end side of the tip side third sealing portion 613 described above. In the present embodiment, the rear end side first sealing portion 621 to the rear end side third sealing portion 623 each have a polygonal appearance. Further, the rear end side first sealing portion 621 and the rear end side third sealing portion 623 have a larger outer diameter than the rear end side second sealing portion 622. Further, the outer diameters of the rear end side first sealing portion 621 and the rear end side third sealing portion 623 are substantially the same. In the following, the outer peripheral surface of the rear end side first sealing portion 621 is referred to as a rear end side first side surface 62a, and the outer peripheral surface of the rear end side second sealing portion 622 is referred to as a rear end side second side surface 62b. The outer peripheral surface of the rear end side third sealing portion 623 is referred to as a rear end side third side surface 62c. Further, the front end side surface of the rear end side first sealing portion 621 is referred to as a rear end side front surface 62d, and the rear end side surface of the rear end side third sealing portion 623 is referred to as a rear end side back surface 62e. In the present embodiment, the rear end side back surface 62e is an example of the back surface.

(Input signal electrode)
The input signal electrode 71 is a member having a plate shape (strip shape) as a whole. The input signal electrode 71 is made of a conductive and elastic metal material for a lead frame. One end of the input signal electrode 71 is connected to the tip end side of the circuit board 50, and the other end extends to the tip end side, and is provided so as to penetrate the tip end side sealing portion 61 (see also FIG. 3). As described above, the input signal electrode 71 has a base portion 711 connected to the circuit board 50 and a protruding portion 712 provided on the tip end side of the base portion 711. The tip end side and the projecting portion 712 of the base portion 711 project outward from the tip end side front surface 61d of the tip end side sealing portion 61 and are exposed. The input signal electrode 71 is connected to the rear end electrode member 43 via a coil spring 45 (see FIG. 4). Although the input signal electrode 71 of the present embodiment has an elongated plate shape, almost the entire area of the base portion 711 except for the protruding portion 712 side is covered by the sealing portion 60 (tip side sealing portion 61). Therefore, it is less likely to bend.

(Input ground electrode)
The input ground electrode 72 as an example of the ground electrode is a member having a plate shape that is a combination of an L shape and a C shape as a whole (see also FIG. 7A described later). The input ground electrode 72 is made of a conductive and elastic metal material for a lead frame. One end of the input ground electrode 72 is connected to the side end side of the circuit board 50, and the other end extends to the side end side, and is provided so as to penetrate the rear end side sealing portion 62 (also in FIG. 3). reference). The rear end side of the input ground electrode 72 is bent at a plurality of points from the side end to the rear end of the rear end side sealing portion 62, and exhibits the most rear end portion (C-shaped). The portion) is located on the rear end side back surface 62e of the rear end side sealing portion 62.

Here, a specific configuration of the input ground electrode 72 will be described.
The input ground electrode 72 is provided so as to project laterally from the rear end side second sealing portion 622 (rear end side second side surface 62b) of the rear end side sealing portion 62, respectively. A dish that has an L-shape and one end is connected to the first protrusion 721 and the second protrusion 722, and a plate that has a C-shape and is connected to the other end of the main body 723. It has a spring portion 724. Here, the first protruding portion 721 and the second protruding portion 722 are bent along the rear end side second side surface 62b. Further, the main body portion 723 is bent along the rear end side second side surface 62b and the rear end side third side surface 62c. Further, the boundary portion between the main body portion 723 and the disc spring portion 724 is bent along the angle formed by the rear end side third side surface 62c and the rear end side back surface 62e.

Further, the disc spring portion 724 has two curved portions 7241 having a C shape and connected to the main body portion 723, and two curved portions 7241 integrated with the curved portion 7241 and bent toward the rear end side from the curved portion 7241. It has a bumping portion 7242. Of these, the curved portion 7241 is provided at a position where it comes into contact with the rear end side back surface 62e of the rear end side sealing portion 62. On the other hand, the abutting portion 7242 is provided at a position where it does not come into contact with the rear end side back surface 62e. As a result, when the disc spring portion 724 is pushed from the rear end side, the abutting portion 7242 is elastically deformed toward the front end side in a state where the curved portion 7241 is in contact with the rear end side back surface 62e. , The disc spring portion 724 functions as a spring (disc spring). The disc spring portion 724 (butting portion 7242) comes into contact with the inner step portion 35h of the rear end outer housing 35.

(Power receiving electrode)
The power receiving electrode 73 is a member having a plate shape (strip shape) as a whole. The power receiving electrode 73 is also made of a conductive and elastic metal material for a lead frame. One end of the power receiving electrode 73 is connected to the rear end side of the circuit board 50, and the other end extends to the rear end side, and is provided so as to penetrate the rear end side sealing portion 62 (see also FIG. 3). ). The rear end side of the power receiving electrode 73 projects outward from the rear end side back surface 62e of the rear end side sealing portion 62 and is exposed. The rear end side of the power receiving electrode 73 is bent as shown in the figure. The power receiving electrode 73 is connected to the power supply line 81 via the connecting member 47.

(Output signal electrode)
The output signal electrode 74 is a member having a plate shape (strip shape) as a whole. The output signal electrode 74 is also made of a conductive and elastic metal material for the lead frame. One end of the output signal electrode 74 is connected to the rear end side of the circuit board 50, and the other end extends to the rear end side, and is provided so as to penetrate the rear end side sealing portion 62 (also in FIG. 3). reference). The rear end side of the power receiving electrode 73 projects outward from the rear end side back surface 62e of the rear end side sealing portion 62 and is exposed. The output signal electrode 74 is adjacent to the power receiving electrode 73 on the rear end side rear surface 62e. The rear end side of the output signal electrode 74 is bent in the opposite direction to the power receiving electrode 73 as shown in the figure. The output signal electrode 74 is connected to the signal line 82 via a connecting member 47.

(Output ground electrode)
The output ground electrode 75 as an example of another ground electrode is a member having a plate shape (strip shape) as a whole. The output ground electrode 75 is also made of a conductive and elastic metal material for the lead frame. One end of the output ground electrode 75 is connected to the rear end side of the circuit board 50, and the other end extends to the rear end side, and is provided so as to penetrate the rear end side sealing portion 62 (also in FIG. 3). reference). The rear end side of the output ground electrode 75 projects outward from the rear end side back surface 62e of the rear end side sealing portion 62 and is exposed. The output ground electrode 75 is adjacent to the output signal electrode 74 on the rear end side rear surface 62e. The rear end side of the output ground electrode 75 is bent in the opposite direction to the output signal electrode 74 (the same direction as the power receiving electrode 73) as shown in the figure. The output ground electrode 75 is connected to the ground wire 83 via a connecting member 47.

(Positional relationship between input ground electrode, power receiving electrode, output signal electrode and output ground electrode)
In the circuit built-in member 46 of the present embodiment, the power receiving electrode 73, the output signal electrode 74, and the output ground electrode 75 are arranged side by side in this order on the rear end side back surface 62e of the rear end side sealing portion 62 in the sealing portion 60. ing. The disc spring portion 724 of the input ground electrode 72 is arranged so as to surround the power receiving electrode 73, the output signal electrode 74, and the output ground electrode 75. Further, the length of the power receiving electrode 73, the output signal electrode 74, and the output ground electrode 75 protruding from the rear end side back surface 62e in the center line direction is the center line direction of the disc spring portion 724 arranged on the rear end side back surface 62e. It is larger than the length (height).

[Electrical connection structure in pressure detector]
Here, the electrical connection structure of the pressure detection device 20 will be described.
(Positive route)
In the pressure detection device 20, the end face (positive electrode) on the rear end side of the piezoelectric element 41 is electrically connected to the rear end electrode member 43 and the coil spring 45. Further, the coil spring 45 is electrically connected to the input signal electrode 71 provided in the circuit built-in member 46. Then, the input signal electrode 71 is electrically connected to the input signal terminal 51a of the circuit board 50 provided in the same circuit built-in member 46. In the following, the electrical path from the rear end side surface of the piezoelectric element 41 to the input signal terminal 51a of the circuit board 50 via the rear end electrode member 43, the coil spring 45, and the input signal electrode 71 is described as “positive”. It is called "path".

(Negative route)
On the other hand, in the pressure detection device 20, the end face (negative electrode) on the tip side of the piezoelectric element 41 is a tip electrode member 42, a diaphragm head 32 (first inner housing 33 and second inner housing 34), and a tip outer housing 31. And is electrically connected to the rear end external housing 35. Further, the rear end outer housing 35 is electrically connected to the input ground electrode 72 provided in the circuit built-in member 46 via the inner step portion 35h provided in the rear end outer housing 35. Then, the input ground electrode 72 is electrically connected to the input ground terminal 51b of the circuit board 50 provided on the same circuit built-in member 46. In the following, from the front end side surface of the piezoelectric element 41, the input ground terminal of the circuit board 50 is passed through the front electrode member 42, the diaphragm head 32, the front outer housing 31, the rear end outer housing 35, and the input ground electrode 72. The electrical path leading to 51b is referred to as a "negative 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 (male screw 31d) comes into contact with the inner peripheral surface of the communication hole 13a. At this time, the cylinder head 13 (and the cylinder block 11) and the negative path have substantially the same potential.

(Relationship between positive and negative paths)
Here, in the pressure detection device 20 of the present embodiment, a negative path exists outside the positive path. In other words, the positive path is contained inside the negative path. The positive path and the negative path are electrically insulated by the insulating member 44, the sealing portion 60, and the air gap formed between the two paths.

[Pressure detection operation by pressure detection device]
Then, the pressure detection operation by the pressure detection device 20 will be described.
When the internal combustion engine 10 is operating, the pressure (combustion pressure) generated in the combustion chamber C is applied to the surface (surface) on the tip end side of the diaphragm head 32. In the diaphragm head 32, the pressure received on its front surface is transmitted to the back surface, and further transmitted from the back surface to the tip electrode member 42. Then, the pressure transmitted to the front end electrode member 42 acts on the piezoelectric element 41 sandwiched between the front end electrode member 42 and the rear end electrode member 43, and the piezoelectric element 41 generates an electric charge according to the received pressure. The electric charge generated in the piezoelectric element 41 is supplied as an electric charge signal to the input signal terminal 51a and the input ground terminal 51b of the circuit board 50 via the positive path and the negative path. The charge signal supplied to the circuit board 50 is converted into an output signal by performing various processes in the processing circuit 52 mounted on the circuit board 50. Then, the output signal output from the output signal terminal 51d and the output ground terminal 51e of the circuit board 50 is transmitted to the control device 100 via the connection member 47 and the connection cable 80, and is used for controlling the internal combustion engine 10. During this period, the processing circuit 52 mounted on the circuit board 50 is supplied with a power supply voltage from the control device 100 via the power receiving terminal 51c and the output grounding terminal 51e.

[Manufacturing procedure of pressure detector]
Subsequently, the manufacturing procedure of the pressure detection device 20 of the present embodiment will be described.
(Manufacturing of the first structure)
First, the back surface of the diaphragm head 32, that is, the rear end side, and the front end side of the first internal housing 33 are opposed to each other and abutted against each other. At this time, the convex portion protruding from the rear end side of the central portion of the diaphragm head 32 is arranged inside the first inner housing 33. Then, in this state, the first structure is obtained by performing laser welding on the boundary portion between the diaphragm head 32 and the first internal housing 33 over one circumference.

(Manufacturing of the second structure)
Next, with respect to the first internal housing 33 of the first structure, the front end electrode member 42, the piezoelectric element 41, the rear end electrode member 43, the insulating member 44, and the second internal housing 34 are attached from the rear end side. Insert in order. At this time, the surface on the front end side of the tip electrode member 42 abuts on the surface on the rear end side of the diaphragm head 32. At this time, the front end side of the second inner housing 34 is housed inside the first inner housing 33, but the rear end side protrudes from the rear end side of the first inner housing 33. Then, the force applied to the second internal housing 34 in the center line direction is adjusted with respect to the fixed first structure, and the preload applied to the piezoelectric element 41 is set to the target value. Then, in this state, the second structure is obtained by performing laser welding on the boundary portion between the first inner housing 33 and the second inner housing 34 over one circumference.

(Manufacturing of the third structure)
Next, the tip outer housing 31 is attached to the second structure from the rear end side with the small diameter portion 31a as the tip side. At this time, the surface on the front end side of the tip outer housing 31 (small diameter portion 31a) abuts on the surface on the rear end side of the diaphragm head 32. Further, the first inner housing 33, the second inner housing 34, the tip electrode member 42, the piezoelectric element 41, the rear end electrode member 43, and the insulating member 44 are housed inside the tip outer housing 31. Then, in this state, the third structure is obtained by performing laser welding on the boundary portion between the diaphragm head 32 and the tip outer housing 31 over one circumference.

(Manufacturing of the 4th structure)
Further, the circuit built-in member 46 (fourth structure) is manufactured in a process different from the above-mentioned first structure to third structure. The details of the manufacturing procedure of the circuit built-in member 46 will be described later.

(Manufacturing of 5th structure)
Next, the fifth structure is formed by fitting the coil spring 45 into the tip side of the protruding portion 712 of the input signal electrode 71, which is located on the tip side of the fourth structure (circuit built-in member 46) and is exposed to the outside. Is obtained. If necessary, the input signal electrode 71 and the coil spring 45 may be integrated by laser welding or the like.

(Manufacturing of 6th structure)
Next, the fifth structure is inserted into the above-mentioned third structure from the rear end side with the coil spring 45 as the tip side. Along with this, among the sealing portions 60 constituting the circuit built-in member 46, the tip side sealing portion 61 is arranged inside the tip outer housing 31. However, the rear end side sealing portion 62 remains exposed to the outside. At this time, the tip-side first sealing portion 611 and the tip-side third sealing portion 613 of the tip-side sealing portions 61 abut against the inner peripheral surface of the tip-side outer housing 31. On the other hand, the tip side second sealing portion 612 faces the inner peripheral surface of the tip outer housing 31 via a gap. Then, the rear end side front surface 62d provided in the sealing portion 60 of the circuit built-in member 46 abuts on the rear end side surface of the tip outer housing 31 (medium diameter portion 31c) with insertion, so that the tip outside The circuit built-in member 46 is positioned with respect to the housing 31, and the sixth structure is obtained.

Further, as the fifth structure is inserted into the third structure, the coil spring 45 attached to the tip end side of the circuit built-in member 46 is arranged inside the second inner housing 34 and the insulating member 44. .. At this time, the tip end side of the coil spring 45 abuts on the rear end side surface of the rear end electrode member 43, and the coil spring 45 is in a contracted state from the original. However, even in this state, there is a space between the rear end side of the rear end electrode member 43 and the front end side of the input signal electrode 71 (protruding portion 712) so that the two do not come into direct contact with each other. It has become.

(Manufacturing of 7th structure)
Next, the rear end external housing 35 is attached to the sixth structure from the rear end side with the first tubular portion 35a as the front end side. At this time, the front end side surface of the rear end outer housing 35 (first cylindrical portion 35a) abuts on the rear end side surface of the front end outer housing 31 (large diameter portion 31b). Further, at this time, the rear end external housing 35 (inner step portion 35h) abuts on the surface on the rear end side of the input ground electrode 72 provided in the circuit built-in member 46, and hits the abutting portion 7242 of the disc spring portion 724. On the other hand, a pressing force toward the tip side is applied. Along with this, in the input ground electrode 72, the abutting portion 7242 in the disc spring portion 724 is deformed to the crushed side, and almost the entire circumference of the abutting portion 7242 comes into contact with the inner step portion 35h of the rear end outer housing 35. .. Then, in this state, the seventh structure is obtained by performing laser welding on the boundary portion between the front end outer housing 31 and the rear end outer housing 35 over one circumference.

(Manufacturing of 8th structure)
Further, in a process different from the first structure to the seventh structure described above, the connecting member 47, the closing member 48, and the connecting cable 80 are arranged in this order, and the connecting member 47 and the connecting cable 80 are arranged via the closing member 48. The eighth structure is obtained by connecting the above.

(Manufacturing of 9th structure)
Then, the eighth structure is inserted into the above-mentioned seventh structure from the rear end side with the connecting member 47 as the front end side. A ninth structure having a pressure detecting device 20 and a connecting cable 80 by connecting the power receiving electrode 73, the output signal electrode 74, and the output grounding electrode 75 provided in the circuit built-in member 46 to the connecting member 47. (Connecting body of the pressure detecting device 20 and the connecting cable 80) is obtained.

[Manufacturing procedure for circuit built-in parts]
Then, the manufacturing procedure of the circuit built-in member 46 will be described.
FIG. 7 is a diagram for explaining a bending process for the metal plate constituting the circuit built-in member 46. Specifically, FIG. 7A is a side view of the circuit built-in member 46 before the metal plate is bent, and FIG. 7B is a side view of the circuit built-in member 46. .. Note that FIG. 7 (b) is the same as that shown in FIG. 5 (b).

First, a known lead frame material is connected to the circuit board 50 to each of the input signal terminal 51a, the input ground terminal 51b, the power receiving terminal 51c, the output signal terminal 51d, and the output ground terminal 51e. Then, by cutting the lead frame material, a connection body having the circuit board 50 and the input signal electrode 71, the input ground electrode 72, the power receiving electrode 73, the output signal electrode 74, and the output ground electrode 75 is obtained. However, at this point, the input ground electrode 72, the power receiving electrode 73, the output signal electrode 74, and the output ground electrode 75 are not bent.

Next, the connection body is set in the molding device, and the sealing portion 60 is formed by molding with a synthetic resin material having insulating properties (here, epoxy resin), and then the sealing portion 60 is taken out from the molding device. The state at this time is shown in FIG. 7 (a). Even at this point, the input ground electrode 72, the power receiving electrode 73, the output signal electrode 74, and the output ground electrode 75 are not bent. More specifically, in the input ground electrode 72, the first protruding portion 721, the second protruding portion 722, the main body portion 723 having an L shape, and the disc spring portion 724 having a C shape are integrated and flat. It is in a state. Further, each of the power receiving electrode 73, the output signal electrode 74, and the output grounding electrode 75 is also in a flat state.

Next, each of the power receiving electrode 73, the output signal electrode 74, and the output grounding electrode 75 is bent. Along with this, the power receiving electrode 73, the output signal electrode 74, and the output grounding electrode 75 have changed from the flat state shown in FIG. 7 (a) to the state shown in FIG. 7 (b) (see also FIG. 5 (a)). And migrate.

Next, the disc spring portion 724 constituting the input ground electrode 72 is bent along the first folding line L1. At this time, in FIG. 7A, bending is performed so that the first folding line L1 becomes a mountain. Along with this, the disc spring portion 724 shifts from a flat state to a state having a curved portion 7241 and two abutting portions 7242. At this time, the boundary portion between the curved portion 7241 and the abutting portion 7242 shifts from a flat state to an obtuse angle state.

Next, at the boundary portion between the main body portion 723 and the disc spring portion 724 constituting the input ground electrode 72, bending processing is performed along the second folding line L2. At this time, in FIG. 7A, bending is performed so that the second folding line L2 becomes a valley. Along with this, the boundary portion between the main body portion 723 and the disc spring portion 724 shifts from a flat state to a state in which a substantially right angle is formed.

Next, the main body portion 723 constituting the input ground electrode 72 is bent along the third folding line L3. At this time, in FIG. 7A, bending is performed so that the third folding line L3 becomes a valley. Along with this, the main body 723 shifts from a flat state to a bent state. At this time, the main body 723 shifts from a flat state to an obtuse angle state.

Next, in the first protruding portion 721 and the second protruding portion 722 constituting the input ground electrode 72, the boundary portion with the sealing portion 60 (the second sealing portion on the rear end side of the rear end side sealing portion 62) Bending is performed along the fourth folding line L4. At this time, in FIG. 7A, bending is performed so that the fourth folding line L4 becomes a valley. Along with this, the boundary portions of the first protruding portion 721 and the second protruding portion 722 with the sealing portion 60 shift from a flat state to a state in which they form a substantially right angle. Along with this, the disc spring portion 724 constituting the input ground electrode 72 moves to the rear end side back surface 62e of the rear end side sealing portion 62. As a result, the input ground electrode 72 shifts from the flat state shown in FIG. 7A to the state shown in FIG. 7B (see also FIG. 5A).
As a result, the circuit built-in member 46 shown in FIG. 7B is obtained.

Here, in the present embodiment, the disc spring portion 724 constituting the input ground electrode 72 is C-shaped. Therefore, when the disc spring portion 724 moves to the rear end side back surface 62e along with the bending along the fourth folding line L4, the power receiving electrode 73 protruding from the rear end side back surface 62e to the rear end side, The disc spring portion 724 is less likely to abut or get caught on the output signal electrode 74 and the output ground electrode 75.

[summary]
As described above, in the present embodiment, the disc spring portion 724 of the input ground electrode 72 connected to the circuit board 50 is arranged on the rear end side rear surface 62e provided in the sealing portion 60 of the circuit built-in member 46. I tried to do it. The disc spring portion 724 is made of metal and has a curved portion 7241 and a bumping portion 7242, so that the disc spring portion 724 has a spring property. Then, in the pressure detection device 20 including the circuit built-in member 46, the circuit built-in member 46 is sandwiched between the front end outer housing 31 and the rear end outer housing 35 forming a negative path of the piezoelectric element 41. Along with this, the disc spring portion 724 of the input ground electrode 72 is pressed against the tip side by the inner step portion 35h provided on the rear end outer housing 35, so that the abutting portion 7242 of the disc spring portion 724 is elastically deformed. bottom. As a result, almost the entire circumference of the abutting portion 7242 can be brought into contact with the inner step portion 35h, and the contact state (conduction state) between the rear end outer housing 35 constituting the negative path and the input ground electrode 72. ) Can be stable and good. Therefore, it is possible to stabilize the ground potential of the circuit board 50 (processing circuit 52), and it is possible to suppress variations in high-frequency characteristics in the output signal output from the processing circuit 52 via the output signal electrode 74. ..

Further, in the present embodiment, the input ground electrode 72, the power receiving electrode 73, the output signal electrode 74, and the output connected to the circuit board 50 are provided on the rear end side rear surface 62e provided in the sealing portion 60 of the circuit built-in member 46. The ground electrode 75 was arranged. Then, on the rear end side back surface 62e, the power receiving electrode 73, the output signal electrode 74, and the output grounding electrode 75 are surrounded by the disc spring portion 724 of the input grounding electrode 72. As a result, the power receiving electrode 73, the output signal electrode 74, and the output grounding electrode 75, which are connected to the control device 100 via the connection cable 80, can be easily shielded by using the input grounding electrode 72. Therefore, the output of the circuit board 50 (processing circuit 52), that is, the output signal output from the processing circuit 52 via the output signal electrode 74 can be stabilized, and the variation in the high frequency characteristics in the output signal can be suppressed. can.

[others]
In the present embodiment, the input ground electrode 72 has a C-shape, but the present invention is not limited to this, and may be, for example, a U-shape or a V-shape, and an O-shape having no end. It may be (ring-shaped).

Further, in the present embodiment, the input ground electrode 72 is projected to the outside from the side surface (second side surface 62b on the rear end side) of the circuit built-in member 46, and is positioned on the back surface 62e on the rear end side by bending. It is not limited to this. The input ground electrode 72 may be exposed directly to the outside from, for example, the rear end side rear surface 62e of the circuit built-in member 46.

Further, in the present embodiment, in the manufacture of the circuit built-in member 46, first, the power receiving electrode 73, the output signal electrode 74, and the output grounding electrode 75 are bent, and then the input grounding electrode 72 is bent. However, it is not limited to this. For example, while the input ground electrode 72 is bent, the power receiving electrode 73 or the like may be bent, and after the input ground electrode 72 is bent, the power receiving electrode 73 or the like is bent. It doesn't matter.

Further, in the present embodiment, the input signal electrode 71 has a flat shape, but the present invention is not limited to this. For example, the input signal electrode 71 may be bent so that the cross section in the direction intersecting the center line direction is V-shaped. By adopting such a configuration, the strength of the input signal electrode 71 is increased, and the deflection is less likely to occur.

1 ... Pressure detection system, 10 ... Internal engine, 20 ... Pressure detection device, 30 ... Housing, 31 ... Tip external housing, 32 ... Diaphragm head, 33 ... First internal housing, 34 ... Second internal housing , 35 ... rear end external housing, 40 ... detection mechanism, 41 ... piezoelectric element, 42 ... tip electrode member, 43 ... rear end electrode member, 44 ... insulating member, 45 ... coil spring, 46 ... circuit built-in member, 47 ... Connecting member, 48 ... Closing member, 50 ... Circuit board, 51 ... Printed wiring board, 52 ... Processing circuit, 60 ... Sealing part, 61 ... Front end side sealing part, 62 ... Rear end side sealing part, 62e ... Rear end side back surface, 71 ... Input signal electrode, 72 ... Input ground electrode, 73 ... Power receiving electrode, 74 ... Output signal electrode, 75 ... Output ground electrode, 80 ... Connection cable, 81 ... Power line, 82 ... Signal line, 83 ... ground wire, 100 ... control device

Claims (9)

A piezoelectric element that outputs an electric signal according to the pressure received from the outside,
A processing circuit that processes the electrical signal input from the piezoelectric element, and extends along the axial direction from one end side close to the piezoelectric element toward the other end side far from the piezoelectric element, and has insulating properties. A circuit-embedded member having a sealing portion that seals the processing circuit, and a ground electrode that is conductive and one is connected to the processing circuit and the other is exposed to the outside of the sealing portion.
Includes an accommodating member that extends along the axial direction, is conductive, is connected to the other end of the piezoelectric element, and accommodates the circuit built-in member.
The ground electrode provided in the circuit built-in member has a spring property and is provided on the back surface of the sealing portion located on the other end side of the sealing portion.
The accommodating member is a pressure detecting device that comes into contact with the ground electrode provided on the back surface of the sealing portion and applies a pressing force toward the one end side. The circuit built-in member further includes an input signal electrode which is conductive and one of which is connected to the processing circuit and the other of which is exposed to the outside of the sealing portion and into which the electrical signal is input.
The pressure detecting device according to claim 1, wherein the input signal electrode projects from one end side of the sealing portion to the outside of the sealing portion. The circuit built-in member
A power receiving electrode that is conductive and one is connected to the processing circuit and the other is exposed to the outside of the sealing portion to receive a power source for operating the processing circuit.
An output signal electrode that is conductive and one is connected to the processing circuit and the other is exposed to the outside of the sealing portion to output an output signal from the processing circuit.
It is conductive and further includes another ground electrode that is connected to the processing circuit and that the other is exposed to the outside of the sealing portion.
The power receiving electrode, the output signal electrode, and the other grounding electrode project outward from the back surface of the sealing portion.
The pressure detecting device according to claim 1 or 2, wherein the ground electrode is arranged so as to surround the power receiving electrode, the output signal electrode, and the other ground electrode on the back surface. The claim is characterized in that the ground electrode projects from the side surface of the sealing portion to the outside of the sealing portion and is provided on the back surface of the sealing portion by bending the ground electrode. The pressure detecting device according to any one of 1 to 3. A piezoelectric element that outputs an electric signal according to the pressure received from the outside,
A processing circuit that processes the electrical signal input from the piezoelectric element, and extending along the axial direction from one end side close to the piezoelectric element toward the other end side far from the piezoelectric element, and having insulating properties. A sealing portion that seals the processing circuit, a ground electrode that is conductive and one is connected to the processing circuit and the other is exposed to the outside of the sealing portion, and one that is conductive and one is exposed to the outside of the sealing portion. A power receiving electrode that is connected to the processing circuit and the other is exposed to the outside of the sealing portion to receive power for operating the processing circuit, and one that is conductive and is connected to the processing circuit. The other is exposed to the outside of the sealing portion, and the output signal electrode that outputs the output signal from the processing circuit and the other are conductive and one is connected to the processing circuit and the other is the sealing. A circuit built-in member having another ground electrode exposed to the outside of the part, and
Including
The power receiving electrode, the output signal electrode, and the other grounding electrode are provided so as to project outward from the back surface of the sealing portion located on the other end side of the sealing portion.
A pressure detecting device provided on the back surface of the sealing portion and arranged so as to surround the power receiving electrode, the output signal electrode, and the other grounding electrode. The ground electrode projects from the side surface of the sealing portion to the outside of the sealing portion, and is provided on the back surface of the sealing portion by bending the ground electrode, and has a C-shape on the back surface. The pressure detecting device according to claim 5, wherein the pressure detecting device is provided. It also has an input signal electrode that is conductive and one is connected to the processing circuit and the other is exposed to the outside of the sealing portion and the electrical signal is input.
The pressure detection device according to claim 5 or 6, wherein the input signal electrode projects from one end side of the sealing portion to the outside of the sealing portion and is not surrounded by the ground electrode. A processing circuit that processes the electrical signal input from the piezoelectric element that outputs an electrical signal according to the pressure received from the outside, and
A sealing portion extending along the axial direction from one end side close to the piezoelectric element toward the other end side far from the piezoelectric element, having insulating properties, and sealing the processing circuit.
It has conductivity and one is connected to the processing circuit and the other has a ground electrode exposed to the outside of the sealing portion.
A circuit-embedded member characterized in that the ground electrode has a spring property and is provided on the back surface of the sealing portion located on the other end side of the sealing portion. A processing circuit that processes the electrical signal input from the piezoelectric element that outputs an electrical signal according to the pressure received from the outside, and
A sealing portion extending along the axial direction from one end side close to the piezoelectric element toward the other end side far from the piezoelectric element, having insulating properties, and sealing the processing circuit.
A ground electrode that is conductive and one is connected to the processing circuit and the other is exposed to the outside of the sealing portion.
A power receiving electrode that is conductive and one is connected to the processing circuit and the other is exposed to the outside of the sealing portion to receive a power source for operating the processing circuit.
An output signal electrode that is conductive and one is connected to the processing circuit and the other is exposed to the outside of the sealing portion to output an output signal from the processing circuit.
It has conductivity and one is connected to the processing circuit and the other has another ground electrode exposed to the outside of the sealing portion.
The power receiving electrode, the output signal electrode, and the other grounding electrode are provided so as to project outward from the back surface of the sealing portion located on the other end side of the sealing portion.
A circuit-embedded member characterized in that the ground electrode is provided on the back surface of the sealing portion and is arranged so as to surround the power receiving electrode, the output signal electrode, and the other ground electrode.

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