JP2018163082A - Pressure detection device, and component for internal combustion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deformation from a shape of a housing structure including an outer side housing, an inner side housing, and a pressure reception member in a pressure detection device.SOLUTION: A pressure detection device 8 comprises: a front housing that includes a front outer side housing 11 and a pressure reception inner side housing 12 which are arranged on a front surface side; a middle housing that is attached on a rear surface side of the front housing to form a front internal space; and a piezoelectric element group that is arranged in the front internal space. The pressure reception inner side housing 12 is configured to integrate a pressure reception section receiving a pressure from an outside to transmit the outside pressure to the piezoelectric element group with a front inner side housing section to be arranged on an inner side of the front outer side housing 11, in which the pressure reception section and the front outer side housing 11 are connected to each other by laser welding.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pressure detection device and a component for an internal combustion engine.

  As a pressure detection device for detecting the pressure in a combustion chamber of an internal combustion engine or the like, a device using a piezoelectric element that outputs a signal corresponding to the received pressure has been proposed.

  Patent Document 1 discloses a cylindrical front outer casing, a front inner casing that is cylindrical and disposed inside the front outer casing, a rear surface of the front outer casing, and a rear surface of the front inner casing. A rear casing disposed across the front surface, the front surface of the front outer housing, and the front surface of the front inner housing, receiving pressure from the outside, and the front outer housing and the front inner housing A pressure detection device is described that includes a plurality of piezoelectric elements that are arranged in an internal space surrounded by a body, a rear housing, and a pressure receiving ring and that output electric charges according to received pressure. And in patent document 1, these are integrated by carrying out laser welding of a front outer housing | casing and a pressure receiving ring over one round, and laser welding the front inner side housing | casing and a pressure receiving ring over one round.

JP 2013-156114 A

Here, when adopting a configuration in which the pressure receiving member that receives pressure from the outside is supported separately by the inner housing from the inside and by the outer housing from the outside, the pressure receiving member and the inner housing And the pressure receiving member and the outer casing need to be connected. For this reason, in the case structure obtained by connecting the inner case, the pressure receiving member, and the outer case, deviation (deformation) from the target shape is likely to occur.
An object of the present invention is to suppress a shift in the shape of a casing structure including an outer casing, an inner casing, and a pressure receiving member in a pressure detection device.

The pressure detection device according to the present invention includes a cylindrical casing having an outer casing and an inner casing accommodated inside the outer casing, and the outer casing and is configured integrally with the inner casing. A pressure receiving member that receives pressure from the outside, and a detection element that is provided between the outer casing and the inner casing and outputs a detection signal corresponding to the pressure received from the pressure receiving member. It is out.
In such a pressure detection device, the pressure detection device further includes another case that is attached to the case and sandwiches the detection element between the pressure receiving member and applies a predetermined preload to the detection element. Can be a feature.
Further, provided between the pressure receiving member and the detection element, provided between the transmission member for transmitting the pressure received by the pressure receiving member to the detection element, and the other casing and the detection element, It may further include an application member that applies a preload to the detection element together with the other casing.
And further including a signal path for outputting a detection signal from the detection element, wherein the housing, the pressure receiving member, the other housing, and the signal path are electrically insulated. Can be a feature.
Further, from another viewpoint, the internal combustion engine component of the present invention is attached to a functional component that functions in a combustion operation of fuel in the combustion chamber of the internal combustion engine, and a portion facing the combustion chamber in the functional component, A pressure detection device for detecting the pressure in the combustion chamber, the pressure detection device having an outer housing and an inner housing housed inside the outer housing, Is a cylindrical housing in which at least a part of the functional component is accommodated, a pressure receiving member configured to be integrated with the inner housing and attached to the outer housing, and receiving pressure from the combustion chamber; A detection element is provided between the outer casing and the inner casing and outputs a detection signal corresponding to the pressure received from the pressure receiving member.

  ADVANTAGE OF THE INVENTION According to this invention, the shift | offset | difference of the shape of the housing | casing structure containing an outer housing | casing, an inner housing | casing, and a pressure receiving member in a pressure detection apparatus can be suppressed.

1 is a schematic configuration diagram of an internal combustion engine according to an embodiment. It is a perspective view of a pressure detection apparatus. It is III-III sectional drawing in FIG. It is IV-IV sectional drawing in FIG. It is a disassembled perspective view of a housing | casing part. It is an exploded sectional view of a case part. (A)-(c) is a figure for demonstrating the structure of a transmission ring. It is a figure for demonstrating the structure of a piezoelectric material. (A)-(c) is a figure for demonstrating the structure of a base ring. It is a figure for demonstrating the structure of an electrode member. It is a figure for demonstrating the electrical connection of the piezoelectric element group in a pressure detection apparatus. It is a figure for demonstrating the electrical connection of a piezoelectric element group, a rear electrode, and a front electrode.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
[Configuration of internal combustion engine]
FIG. 1 is a schematic configuration diagram of an internal combustion engine 1 according to the present embodiment.
The internal combustion engine 1 includes a cylinder block 2 having a cylinder 2a, a piston 3 that reciprocates in the cylinder 2a, a cylinder head 4 that is fastened to the cylinder block 2 and forms a combustion chamber C together with the cylinder 2a, the piston 3, and the like. It has. The internal combustion engine 1 is attached to the cylinder head 4 and ignites the fuel to explode the air-fuel mixture in the combustion chamber C. The internal combustion engine 1 is attached to the cylinder head 4 and injects fuel into the combustion chamber C. In addition, an injector unit 6 for detecting the pressure in the combustion chamber C is further provided. The cylinder head 4 is provided with two communication holes for communicating the combustion chamber C and the outside. One of the communication holes is a spark plug 5 and the other communication hole is an injector unit 6. It is attached in a penetrating state.

[Injector unit configuration]
An injector unit 6 as an example of an internal combustion engine component is a fuel injection device 7 that injects fuel into the combustion chamber C, and a pressure detection device 8 that is attached to the fuel injection device 7 and detects the pressure in the combustion chamber C. And have. Here, the fuel injection device 7 as an example of a functional component includes a main body portion 7a disposed outside the combustion chamber C, and a columnar tip portion 7b extending outward from the main body portion 7a. . On the other hand, the pressure detection device 8 is attached to the distal end side of the distal end portion 7 b of the fuel injection device 7. The part attached to the front end side in the front-end | tip part 7b of the fuel-injection apparatus 7 among the pressure detection apparatuses 8 is equipped with the cylindrical shape which has a through-hole so that it may mention later. For this reason, the tip of the tip 7b of the fuel injection device 7, that is, the portion where the nozzle for injecting the fuel is formed is exposed in the combustion chamber C through the through hole.

[Configuration of pressure detector]
Next, the configuration of the pressure detection device 8 in the injector unit 6 will be described.
FIG. 2 is a perspective view of the pressure detection device 8. 3 is a cross-sectional view taken along the line III-III in FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG.
In the following, in the pressure detection device 8 that constitutes the injector unit 6 together with the fuel injection device 7, the side facing the combustion chamber C (the upper side in FIGS. 2 to 4) is referred to as “front side”. The opposite side (the lower side in FIGS. 2 to 4) is referred to as the “back side”.

  The pressure detection device 8 according to the present embodiment has a cylindrical shape as a whole, penetrates from the front surface side to the back surface side, and opens an opening 10a that accommodates the distal end side of the distal end portion 7b in the fuel injection device 7 shown in FIG. (Through hole) is provided. In the following description, the center line direction of the opening 10a having a cylindrical shape (indicated by a one-dot chain line in FIGS. 2 and 3) is simply referred to as a center line direction.

  Further, the pressure detection device 8 has a cylindrical shape when viewed as a whole, and includes a casing portion 10 in which a cylindrical front inner space 10b and a rear inner space 10c are provided. Furthermore, the pressure detection device 8 includes a transmission ring 20, a piezoelectric element group 30, and a base ring 40 that are disposed in a front internal space 10 b provided in the housing unit 10. Here, the transmission ring 20, the piezoelectric element group 30, and the base ring 40 are arranged in this order from the front side to the back side. Furthermore, the pressure detection device 8 extends from the inside of the front internal space 10b provided in the housing unit 10 to the back side, so that the first electrode is provided across the front internal space 10b and the rear internal space 10c. A member 51 and a second electrode member 52 are provided. The pressure detection device 8 is connected to the first electrode member 51 and extended to the back side, and is connected to an external electrode (not shown) provided in the fuel injection device 7. The second connection electrode 62 is connected to the connection electrode 61 and the second electrode member 52 and extended to the back side, and can be connected to an external electrode (not shown) provided in the fuel injection device 7. And. Here, the first connection electrode 61 functions as a positive electrode, and the second connection electrode 62 functions as a negative electrode.

Now, the constituent members of the pressure detection device 8 will be described in detail.
[Case]
FIG. 5 is an exploded perspective view of the casing 10, and FIG. 6 is an exploded cross-sectional view of the casing 10. Here, in FIGS. 5 and 6, the upper side in the figure is the front side, and the lower side in the figure is the back side. Hereinafter, the configuration of the housing unit 10 will be described with reference to FIGS. 5 and 6 in addition to FIGS. 1 to 4.

  The casing unit 10 is disposed on the front side, a front outer casing 11 and a pressure-receiving front inner casing 12, a middle casing 13 disposed between the front side and the back side, and a back side. A rear outer casing 14 and a rear inner casing 15 are provided. Here, the outer diameter of the casing 10 (the outer diameter of the front outer casing 11 and the rear outer casing 14) is 7.4 mm, and the inner diameter of the casing section 10 (the inner diameter of the pressure receiving front inner casing 12). ) Is 4.9 mm. In the following description, both the front outer casing 11 and the pressure-receiving front inner casing 12 may be collectively referred to as a “front casing” (an example of a casing). Both of the inner housings 15 may be collectively referred to as “rear housings”.

(Front outer casing)
The front outer casing 11 as an example of the outer casing is a member having a cylindrical shape as a whole. A notch 111 for fitting an edge portion 1214 (details will be described later) of the pressure receiving front inner housing 12 is formed outside the front end of the front outer housing 11. Further, in the inner peripheral surface of the front outer casing 11, a small inner diameter portion 112 is provided at the front side portion, and a large inner diameter portion 113 having an inner diameter larger than the small inner diameter portion 112 is provided at the rear side portion. Is provided.

  And since the front outer housing | casing 11 exists in the position which faces the combustion chamber C which may become high temperature, or the position close | similar to the combustion chamber C, the material which endures the use temperature environment of -40 degreeC-350 degreeC at least is used. It is desirable to produce it. In this example, since the front outer casing 11 and the pressure-receiving front inner casing 12 are fixed by welding, the front outer casing 11 is desirably made of a metal material. Specifically, the front outer casing 11 may be configured using a stainless steel material having high heat resistance and conductivity, such as JIS standard SUS630, SUS316, SUS430, or the like.

(Pressure-receiving front inner casing)
The pressure-receiving front inner housing 12 has an annular shape and is provided on the front side, a pressure-receiving portion 121 that receives pressure from the outside, and a cylindrical shape that has a cylindrical shape from the inner peripheral side end portion to the back side. The front inner casing 122 that extends is integrated and configured.

  Among these, the pressure receiving part 121 as an example of a pressure receiving member is provided along the circumferential direction on the front surface side of the pressure receiving part 121 having an annular shape, and is recessed toward the back side over the entire circumference, and the back surface of the recessed part 1211. And a convex portion 1212 protruding from the rear side. The pressure receiving portion 121 is provided inside and outside the recess 1211 and has a flat portion 1213 that is flat and an edge portion 1214 that protrudes from the outer end of the flat portion 1213 to the back side. . Furthermore, out of the outer peripheral surface of the front inner housing 122 as an example of the inner housing, the large outer diameter portion 1221 is located outside the large outer diameter portion 1221 in the portion on the front side, and the outer diameter surface 1221 in the portion on the back side. Small outer diameter portions 1222 having a small diameter are provided.

  Here, the outer diameter of the pressure receiving portion 121 is substantially the same as the outer diameter of the front outer housing 11, and the outer diameter of the front inner housing portion 122 is smaller than the inner diameter of the front outer housing 11. The front inner housing 122 is disposed concentrically with the front outer housing 11 inside the front outer housing 11, and the pressure receiving portion 121 is disposed so as to close the front side of the front outer housing 11. . At this time, the edge portion 1214 of the pressure receiving portion 121 is fitted into the notch 111 of the front outer casing 11.

  The front outer casing 11 and the pressure receiving front inner casing 12 are the front end of the front outer casing 11 (around the notch 111) and the edge of the pressure receiving portion 121 of the pressure receiving front inner casing 12. It is integrated by welding 1214 and constitutes a front case. As a result, the cross section of the front case including the front outer case 11 and the pressure-receiving front inner case 12 has a concave shape. In the front housing, the inner peripheral surface (small inner diameter portion 112 and large inner diameter portion 113) of the front outer housing 11 and the outer peripheral surface (large outer diameter) of the front inner housing portion 122 of the pressure receiving front inner housing 12 are used. The portion 1221 and the small outer diameter portion 1222 are opposed to each other.

  Since the pressure-receiving front inner housing 12 exists at a position facing the combustion chamber C that can be high temperature or a position close to the combustion chamber C, a material that can withstand at least a temperature range of −40 ° C. to 350 ° C. is used. It is desirable to produce it. In this example, the front outer casing 11 and the pressure receiving front inner casing 12 are welded to form the front casing. Therefore, the pressure receiving front inner casing 12 is manufactured using a metal material. It is desirable. Specifically, the pressure-receiving front inner housing 12 may be configured using a stainless steel material having high heat resistance and conductivity, such as JIS standard SUS630, SUS316, SUS430, or the like.

(Middle housing)
The middle casing 13 as an example of another casing is a member having a cylindrical shape as a whole. The middle casing 13 is provided with a first through hole 131 and a second through hole 132 that penetrate the front surface and the back surface along the center line direction. Here, the first through hole 131 and the second through hole 132 are arranged with an interval of 180 °. Further, of the inner peripheral surface of the middle casing 13, a large inner diameter portion 133 is provided in a portion on the front side, and a small inner diameter portion 134 having an inner diameter smaller than that of the large inner diameter portion 133 is provided in a portion on the back side. It has been.

  Here, the inner diameters of the first through-hole 131 and the second through-hole 132 are the outer diameters of the linear portions 502 (details will be described later) of the electrode body 500 constituting the first electrode member 51 and the second electrode member 52. Bigger than. Further, the outer diameter of the middle casing 13 is smaller than the inner diameter of the large inner diameter portion 113 of the front outer casing 11. Further, the inner diameter of the large inner diameter portion 133 of the middle casing 13 is substantially the same as the outer diameter of the large outer diameter section 1221 of the front inner casing section 122, and the inner diameter of the small inner diameter section 134 of the middle casing 13 is This is substantially the same as the outer diameter of the small outer diameter portion 1222 in the inner housing portion 122.

  The front casing (the front outer casing 11 and the pressure-receiving front inner casing 12) and the middle casing 13 are arranged such that the middle casing 13 is the front casing from the rear side of the front casing with the large inner diameter portion 133 as the front side. The front inner housing 122 and the middle housing 13 are welded together while being inserted into the recess. At this time, the inner peripheral surface of the large inner diameter portion 113 in the front outer casing 11 and the outer peripheral surface of the middle casing 13 are opposed to each other with a gap. Further, the outer peripheral surface of the large outer diameter portion 1221 in the front inner housing portion 122 and the inner peripheral surface of the large inner diameter portion 133 in the middle housing 13 are in contact, and the small outer diameter portion 1222 in the front inner housing portion 122 is contacted. Are in contact with the inner peripheral surface of the small inner diameter portion 134 of the middle casing 13. As a result, a cylindrical front internal space 10 b is formed between the front housing and the middle housing 13.

  Since the middle casing 13 is present at a position facing the combustion chamber C that can be at a high temperature or a position close to the combustion chamber C, the middle casing 13 is manufactured using a material that can withstand an operating temperature environment of at least −40 ° C. to 350 ° C. It is desirable to do. In this example, since the pressure receiving front inner casing 12 and the middle casing 13 are fixed by welding, the middle casing 13 is preferably manufactured using a metal material. Specifically, the middle casing 13 may be configured using a stainless steel material having high heat resistance and conductivity, such as JIS standard SUS630, SUS316, SUS430, or the like.

(Rear outer casing)
The rear outer casing 14 is a member having a cylindrical shape as a whole. Of the outer peripheral surface of the rear outer casing 14, the large outer diameter portion 141 is located at the front side, and the outer diameter is smaller than the large outer diameter portion 141 at the rear side of the large outer diameter portion 141. First medium outer diameter portions 142 are provided. Further, a small outer diameter portion 143 having an outer diameter smaller than that of the first intermediate outer diameter portion 142 is provided at a portion on the back side of the first intermediate outer diameter portion 142, and a small outer diameter portion is provided on a portion on the back side of the small outer diameter portion 143. A second middle outer diameter portion 144 having an outer diameter larger than that of the diameter portion 143 is provided. Further, of the inner peripheral surface of the rear outer casing 14, the large inner diameter portion 145 is located at the front side, and the inner diameter portion 145 is smaller than the large inner diameter portion 145 at the rear side of the large inner diameter portion 145. An inner diameter portion 146 is provided. In the rear outer casing 14, the large outer diameter portion 141 provided on the outer peripheral surface and the large inner diameter portion 145 provided on the inner peripheral surface face each other, and the first medium outer diameter provided on the outer peripheral surface. The portion 142, the small outer diameter portion 143, the second middle outer diameter portion 144 and the small inner diameter portion 146 provided on the inner peripheral surface are opposed to each other.

  Here, the outer diameter of the large outer diameter portion 141 in the rear outer casing 14 is substantially the same as the outer diameter of the front outer casing 11. The inner diameter of the large inner diameter portion 145 in the rear outer casing 14 is substantially the same as the inner diameter of the large inner diameter section 113 in the front outer casing 11.

  Since the rear outer casing 14 is present at a position facing the combustion chamber C that can be at a high temperature or a position close to the combustion chamber C, at least a material that can withstand an operating temperature environment of −40 ° C. to 350 ° C. is used. It is desirable to produce it. In this example, since the front outer casing 11 and the rear outer casing 14 are integrated by welding, it is desirable that the rear outer casing 14 be manufactured using a metal material. Specifically, the rear outer housing 14 may be configured using a stainless steel material having high heat resistance and conductivity, such as JIS standard SUS630, SUS316, SUS430, or the like.

(Rear inner housing)
The rear inner casing 15 is a member having a cylindrical shape as a whole. Of the outer peripheral surface of the rear inner casing 15, the small outer diameter portion 151 is larger at the front side, and the outer diameter is larger than the small outer diameter portion 151 at the rear side of the small outer diameter portion 151. The outer diameter portion 153 has a larger outer diameter than the small outer diameter portion 151 and a smaller outer diameter than the large outer diameter portion 152. Is provided.

  Here, the outer diameter of the small outer diameter portion 151 in the rear inner casing 15 is smaller than the inner diameter of the large outer diameter section 141 in the rear outer casing 14. Further, the outer diameter of the large outer diameter portion 152 in the rear inner casing 15 is substantially the same as the inner diameter of the large outer diameter section 141 in the rear outer casing 14. Further, the outer diameter of the middle outer diameter portion 153 in the rear inner housing 15 is substantially the same as the inner diameter of the small inner diameter portion 146 in the rear outer housing 14.

  The rear inner casing 15 is disposed concentrically with the rear outer casing 14 inside the rear outer casing 14. Then, from the front side of the rear outer casing 14, the rear inner casing 15 is inserted with the middle outer diameter portion 153 as the back side, the steps of the large inner diameter portion 145 and the small inner diameter portion 146 in the rear outer casing 14, and the rear inner side A rear housing including the rear outer housing 14 and the rear inner housing 15 is formed by pushing the rear inner housing 15 until the steps of the large outer diameter portion 152 and the middle outer diameter portion 153 in the housing 15 abut against each other. The At this time, the inner peripheral surface of the large inner diameter portion 145 of the rear outer housing 14 and the outer peripheral surface of the small outer diameter portion 151 of the rear inner housing 15 are opposed to each other through a gap. Further, the inner peripheral surface of the large inner diameter portion 145 of the rear outer casing 14 and the outer peripheral surface of the large outer diameter section 152 of the rear inner casing 15 are in contact with each other with almost no gap. Furthermore, the inner peripheral surface of the small inner diameter portion 146 of the rear outer casing 14 and the outer peripheral surface of the middle outer diameter section 153 of the rear inner casing 15 are in contact with each other with almost no gap. As described above, the rear inner casing 15 is integrated by being fitted into the rear outer casing 14 to constitute a rear casing.

  The rear casing (rear outer casing 14 and rear inner casing 15) and the front casing (front outer casing 11 and pressure receiving front inner casing 12) to which the middle casing 13 is attached are the front outer casing. The end on the front side of the rear outer casing 14 is abutted against the end on the back side of the body 11 and the end on the front side of the rear inner casing 15 is abutted against the end on the back side of the middle casing 13. In this state, the end on the back side of the front outer casing 11 and the end on the front side of the rear outer casing 14 are welded together to constitute the casing 10. As a result, a cylindrical rear internal space 10c is formed between the middle casing 13 and the rear casing.

  Here, the front internal space 10b and the rear internal space 10c provided on the back side of the front internal space 10b include a first through hole 131 and a second through hole 132 provided in the middle housing 13, and a middle housing. The body 13 communicates with the gaps provided between the outer peripheral surface of the body 13 and the inner peripheral surfaces of the front outer casing 11 and the rear outer casing 14.

  Since the rear inner casing 15 is present at a position facing the combustion chamber C that can be high temperature or a position close to the combustion chamber C, at least a material that can withstand an operating temperature environment of −40 ° C. to 350 ° C. is used. It is desirable to produce it. Specifically, the rear inner housing 15 may be configured using a stainless steel material having high heat resistance and conductivity, such as JIS standard SUS630, SUS316, SUS430, or the like.

[Transmission ring]
FIG. 7 is a view for explaining the configuration of the transmission ring 20. Here, FIG. 7A is a view of the transmission ring 20 as viewed from the front surface 201 side, FIG. 7B is a view of the transmission ring 20 as viewed from the back surface 202 side, and FIG. 2 is a cross-sectional view of a transmission ring main body 21 constituting the transmission ring 20. FIG. Hereinafter, the configuration of the transmission ring 20 will be described with reference to FIG. 7 in addition to FIGS. 1 to 6.

  The transmission ring 20 as an example of the transmission member is a member having an annular shape as a whole. The transmission ring 20 has an annular shape, and includes a transmission ring body 21 having a front surface 201 and a back surface 202 on the front surface side, and a front electrode 22 formed on the back surface 202 of the transmission ring body 21. I have.

  Here, the cross section of the transmission ring main body 21 is rectangular, and the length (thickness) in the center line direction from the front side to the back side is the length in the radial direction (thickness) orthogonal to the center line direction and the circumferential direction. (See FIG. 7C). Further, the outer diameter of the transmission ring body 21 is smaller than the inner diameter of the small inner diameter portion 112 of the front outer casing 11, and the inner diameter of the transmission ring main body 21 is the outer diameter of the large outer diameter section 1221 of the front inner casing section 122. Bigger than. And the transmission ring main body 21 is comprised with ceramic materials, such as an alumina, which have heat resistance and insulation.

  Further, the front electrodes 22 provided on the back surface 202 of the transmission ring main body 21 are formed along the circumferential direction and arranged side by side in the circumferential direction, and the first front electrode 221, the second front electrode 222, and the third. A front electrode 223 is provided. Here, the first front electrode 221 to the third front electrode 223 are arranged at equal intervals while being shifted by 120 °. The first front electrode 221 to the third front electrode 223 constituting the front electrode 22 are configured by laminating a single conductive metal thin film or a plurality of layers on the transmission ring main body 21.

  And the transmission ring 20 is arrange | positioned in the front interior space 10b so that the surface 201 used as the front side may contact | abut the edge part of the back side of the convex part 1212 of the pressure receiving part 121. FIG. At this time, the outer peripheral surface of the transmission ring 20 (transmission ring main body 21) and the inner peripheral surface of the front outer casing 11 are opposed to each other with a gap. Moreover, the inner peripheral surface of the transmission ring 20 (transmission ring main body 21) and the outer peripheral surface of the front inner housing part 122 are opposed to each other with a gap. Therefore, the front electrode 22 provided on the back surface 202 of the transmission ring main body 21 does not contact the front outer casing 11 and the front inner casing portion 122 (pressure receiving front inner casing 12).

[Piezoelectric element group]
The piezoelectric element group 30 of the present embodiment includes a first piezoelectric element 31 to a sixth piezoelectric element 36 that are formed along the circumferential direction and arranged side by side in the circumferential direction. Here, in the present embodiment, when the pressure detecting device 8 is viewed from the front side, the first piezoelectric element 31 to the sixth piezoelectric element 36 are shifted clockwise by 60 ° in this order, etc. They are arranged at intervals (see FIG. 4). The first piezoelectric element 31 to the sixth piezoelectric element 36 as an example of the detection element have a common structure.

(Piezoelectric)
FIG. 8 is a diagram for explaining the configuration of the piezoelectric body 300 that constitutes the first piezoelectric element 31 to the sixth piezoelectric element 36. Hereinafter, the configuration of the piezoelectric body 300 (the first piezoelectric element 31 to the sixth piezoelectric element 36) will be described with reference to FIG. 8 in addition to FIGS.

  The piezoelectric body 300 of the present embodiment has a rectangular parallelepiped shape. Here, the piezoelectric body 300 has a length of 1.5 mm, a width of 0.3 mm, and a height of 0.5 mm. In the pressure detection device 8, the first piezoelectric element 31 to the sixth piezoelectric element 36 are configured by arranging the long sides of each piezoelectric body 300 along the circumferential direction of the transmission ring 20. And the 1st piezoelectric element 31-the 6th piezoelectric element 36 are arrange | positioned in the front internal space 10b so that each front side may contact | abut the back surface 202 of the transmission ring 20. FIG.

  As the piezoelectric body 300 of the present embodiment, a piezoelectric body having a piezoelectric action of the piezoelectric longitudinal effect is used. The piezoelectric longitudinal effect refers to an action of generating charges on the surface of the piezoelectric body 300 in the charge generation axis direction when an external force is applied to the stress application axis in the same direction as the charge generation axis of the piezoelectric body 300. The piezoelectric body 300 of the present embodiment is housed in the front internal space 10b so that the center line direction is the direction of the stress application axis.

  Here, in the present embodiment, a surface of the piezoelectric body 300 that outputs a positive charge due to the piezoelectric action is referred to as a positive charge output surface 301, and a surface that outputs a negative charge is referred to as a negative charge output surface 302. In the present embodiment, in the piezoelectric body 300, the upper surface in the drawing (the surface having a length of 1.5 mm × the width of 0.3 mm) is the positive charge output surface 301, and the back surface is a negative charge. It becomes the output surface 302. Note that electrodes (positive electrode film, negative electrode film) made of a metal thin film or the like may be provided on the positive charge output surface 301 and the negative charge output surface 302 of the piezoelectric body 300 as necessary.

  Next, the case where the piezoelectric body 300 that shows the piezoelectric lateral effect is used will be exemplified. The piezoelectric lateral effect refers to an action in which charges are generated on the surface of the piezoelectric body 300 in the direction of the charge generation axis when an external force is applied to the stress application axis at a position orthogonal to the charge generation axis of the piezoelectric body 300. A plurality of piezoelectric layers thinly formed in a thin plate shape may be stacked, and by stacking in this manner, the charge generated in the piezoelectric body 300 can be efficiently collected and the sensitivity of the sensor can be increased. .

  Here, as the piezoelectric single crystal constituting the piezoelectric body 300, a langasite crystal having a piezoelectric longitudinal effect and a piezoelectric transverse effect (Langasite, Langatite, Langanite, Langatite (LTGA) in which a part of gallium is replaced with aluminum). ), Quartz, gallium phosphate, and the like. In this embodiment, a langate single crystal is used as the piezoelectric body 300.

  Further, in the piezoelectric element group 30, for the first piezoelectric element 31, the third piezoelectric element 33, the fourth piezoelectric element 34, and the sixth piezoelectric element 36, the positive charge output surface 301 of the piezoelectric body 300 is the front side, that is, the transmission ring. It arrange | positions so that it may face 20 side. On the other hand, in the piezoelectric element group 30, the remaining second piezoelectric element 32 and fifth piezoelectric element 35 are arranged such that the negative charge output surface 302 of the piezoelectric body 300 faces the front side, that is, the transmission ring 20 side. .

  As shown in FIG. 7B, the entire surface of the positive charge output surface 301 of the first piezoelectric element 31 is in contact with the first front electrode 221 provided on the transmission ring 20. Further, the entire surface of the negative charge output surface 302 of the second piezoelectric element 32 is in contact with the second front electrode 222 provided on the transmission ring 20. Further, the entire surface of the positive charge output surface 301 of the third piezoelectric element 33 is in contact with the second front electrode 222 provided on the transmission ring 20. Furthermore, the entire surface of the positive charge output surface 301 of the fourth piezoelectric element 34 is in contact with the third front electrode 223. Further, the entire surface of the negative charge output surface 302 of the fifth piezoelectric element 35 is in contact with the third front electrode 223 provided on the transmission ring 20. The entire surface of the positive charge output surface 301 of the sixth piezoelectric element 36 is in contact with the first front electrode 221 provided on the transmission ring 20.

[Base ring]
FIG. 9 is a view for explaining the configuration of the base ring 40. Here, FIG. 9A is a view of the base ring 40 as viewed from the front surface 401 side, and FIG. 9B is a view of the base ring 40 as viewed from the back surface 402 side, and FIG. These are sectional views of a base ring main body 41 constituting the base ring 40. Hereinafter, the configuration of the base ring 40 will be described with reference to FIG. 9 in addition to FIGS. 1 to 8.

  The base ring 40 as an example of a provision member is a member which exhibits an annular shape as a whole. The base ring 40 has an annular shape, and includes a base ring body 41 having a front surface 401 and a rear surface 402 on the front surface side, and a rear electrode formed on the surface 401 of the base ring body 41. 42.

  Here, the cross section of the base ring main body 41 is rectangular, and the length (thickness) in the center line direction from the front side to the back side is the length in the radial direction perpendicular to the center line direction and the circumferential direction ( (Thickness) is smaller (see FIG. 9C). Further, a first groove portion 411 and a second groove portion 412 are provided on the outer peripheral surface of the base ring main body 41 along the center line direction. And the 1st groove part 411 and the 2nd groove part 412 are arrange | positioned in the state shifted 180 degrees.

  Further, the outer diameter of the base ring main body 41 is substantially the same as the outer diameter of the transmission ring main body 21, and the inner diameter of the base ring main body 41 is substantially the same as the inner diameter of the transmission ring main body 21. Further, the inner diameters of the first groove portion 411 and the second groove portion 412 are larger than the outer diameter of the linear portion 502 (details will be described later) of the electrode body 500 constituting the first electrode member 51 and the second electrode member 52. And the base ring main body 41 is comprised with ceramic materials, such as an alumina, which have heat resistance and insulation.

  In addition, the rear electrodes 42 provided on the surface 401 of the base ring body 41 are formed along the circumferential direction and arranged side by side in the circumferential direction, and the first rear electrode 421, the second rear electrode 422, and the first Three rear electrodes 423 are provided. Here, the first rear electrode 421 to the third rear electrode 423 are arranged at equal intervals while being shifted by 120 °. The first rear electrode 421 to the third rear electrode 423 constituting the rear electrode 42 are configured by laminating a single layer or a plurality of layers of a highly conductive metal thin film on the base ring body 41.

  Further, the first groove portion 411 provided in the base ring body 41 is provided corresponding to a portion between the portion where the first rear electrode 421 is provided and the portion where the third rear electrode 423 is provided. It is done. On the other hand, the second groove portion 412 provided in the base ring main body 41 is provided corresponding to a portion where the second rear electrode 422 is provided.

  The base ring 40 has a front surface 401 that abuts against the back side of the first piezoelectric element 31 to the sixth piezoelectric element 36 and a back surface 402 that a back side faces the front side of the middle housing 13. Further, it is disposed in the front internal space 10b. At this time, the first groove portion 411 provided in the base ring main body 41 is disposed at a position overlapping the first through hole 131 provided in the middle housing 13. Further, the second groove portion 412 provided in the base ring main body 41 is disposed at a position overlapping the second through hole 132 provided in the middle housing 13. At this time, the outer peripheral surface of the base ring 40 (base ring main body 41) and the inner peripheral surface of the front outer casing 11 are opposed to each other with a gap. Moreover, the inner peripheral surface of the base ring 40 (base ring main body 41) and the outer peripheral surface of the front inner housing part 122 are opposed to each other with a gap. Therefore, the rear electrode 42 provided on the back surface 402 of the base ring main body 41 does not contact the front outer casing 11 and the front inner casing portion 122 (pressure receiving front inner casing 12).

  In this pressure detection device 8, with the piezoelectric element group 30 in between, the back surface 202 (surface on which the front electrode 22 is provided) of the transmission ring 20 is on the front side, and the front surface 201 (rear side) of the base ring 40 is on the back side. The surface on which the electrode 42 is provided) is disposed. At this time, for example, when viewed from the front side, one end side of the first front electrode 221 and the other end side of the first rear electrode 421 face each other, and one end side of the first rear electrode 421 and the other side of the second front electrode 222 The end side is opposite. Also, one end side of the second front electrode 222 and the other end side of the second rear electrode 422 face each other, and one end side of the second rear electrode 422 and the other end side of the third front electrode 223 face each other. Furthermore, one end side of the third front electrode 223 and the other end side of the third rear electrode 423 face each other, and one end side of the third rear electrode 423 and the other end side of the first front electrode 221 face each other.

  For this reason, the entire surface of the negative charge output surface 302 of the first piezoelectric element 31 is in contact with the first rear electrode 421 provided on the base ring 40. Further, the entire surface of the positive charge output surface 301 of the second piezoelectric element 32 is in contact with the first rear electrode 421 provided on the base ring 40. Further, the entire surface of the negative charge output surface 302 of the third piezoelectric element 33 is in contact with the second rear electrode 422 provided on the base ring 40. Furthermore, the entire surface of the negative charge output surface 302 of the fourth piezoelectric element 34 is in contact with the second rear electrode 422 provided on the base ring 40. Further, the entire surface of the positive charge output surface 301 of the fifth piezoelectric element 35 is in contact with the third rear electrode 423 provided on the base ring 40. The entire surface of the negative charge output surface 302 of the sixth piezoelectric element 36 is in contact with the third rear electrode 423 provided on the base ring 40.

[First electrode member and second electrode member]
The first electrode member 51 and the second electrode member 52 of the present embodiment are those having a common structure.
(Electrode body)
FIG. 10 is a diagram for explaining a configuration of an electrode body 500 used as the first electrode member 51 and the second electrode member 52. Hereinafter, the configuration of the electrode body 500 will be described with reference to FIG. 10 in addition to FIGS. 1 to 9.

  The electrode body 500 has a Z-shaped cross section and is positioned on the front surface side, and has a linear shape and extends from the back surface side of the Z-shaped portion 501 to the back surface side along the center line direction. The linear portion 502 is integrated. Further, the Z-shaped portion 501 has a front flat surface 5011 having a surface facing the front side and the back side and positioned on the foremost side, and a surface facing the front side and the back side and positioned on the most back side. A rear flat portion 5012 and an oblique portion 5013 extending obliquely from one end of the front flat portion 5011 toward one end of the rear flat portion 5012. The linear portion 502 extends from the other end of the rear flat portion 5012 toward the back side.

  Here, the front flat part 5011 and the rear flat part 5012 in the Z-shaped part 501 have a substantially parallel positional relationship. Further, the linear portion 502 and the front flat portion 5011 and the rear flat portion 5012 in the Z-shaped portion 501 have a substantially vertical positional relationship. The electrode body 500 is manufactured by bending a strip-shaped plate material made of Kovar (an alloy in which nickel and cobalt are mixed in iron) that is also used for an IC lead frame or the like. For this reason, the Z-shaped part 501 in the electrode body 500 functions as a compression spring that can be expanded and contracted in the center line direction.

  Here, the height in the center line direction of the Z-shaped portion 501 before being attached to the pressure detection device 8 is that of the first piezoelectric element 31 to the sixth piezoelectric element 36 (piezoelectric body 300) constituting the piezoelectric element group 30. It is slightly larger than each height (length from the positive charge output surface 301 to the negative charge output surface 302: 0.5 mm in this example). Further, the outer diameter of the linear portion 502 is smaller than the inner diameters of the first through hole 131 and the second through hole 132 provided in the middle casing 13, and the first groove portion 411 and the first groove portion 411 provided in the base ring 40. It is smaller than the inner diameter of the two groove portions 412.

(First electrode member)
Next, the arrangement of the first electrode member 51 in the pressure detection device 8 will be described.
The Z-shaped part 501 of the first electrode member 51 is disposed in the front internal space 10 b of the housing part 10. On the other hand, the linear portion 502 of the first electrode member 51 has a first groove portion 411 provided in the base ring 40 and a first case provided in the middle housing 13 from the front internal space 10b of the housing portion 10. It extends through the through hole 131 to the rear internal space 10c of the housing 10 (see FIG. 3).

  At this time, the front side of the front flat portion 5011 in the Z-shaped portion 501 of the first electrode member 51 is in contact with the first front electrode 221 provided on the back surface 202 of the transmission ring body 21 in the transmission ring 20 ( (Refer FIG.7 (b)). On the other hand, the back side of the rear flat part 5012 in the Z-shaped part 501 of the first electrode member 51 is in contact with the surface 401 of the base ring body 41 in the base ring 40 and not in contact with the rear electrode 42 ( FIG. 9 (a)).

  At this time, the Z-shaped portion 501 of the first electrode member 51 is sandwiched between the transmission ring 20 and the base ring 40 and is compressed in the center line direction. And the 1st electrode member 51 and the housing | casing part 10 have opposed the transmission ring 20 (transmission ring main body 21), the base ring 40 (base ring main body 41), and the space | gap.

(Second electrode member)
Next, the arrangement of the second electrode member 52 in the pressure detection device 8 will be described.
The Z-shaped part 501 of the second electrode member 52 is disposed in the front internal space 10 b of the housing part 10. On the other hand, the linear portion 502 of the second electrode member 52 extends from the front internal space 10b of the housing portion 10 to the second groove portion 412 provided in the base ring 40 and the second housing portion provided in the middle housing 13. It extends through the through-hole 132 to the rear internal space 10c of the housing 10 (see FIG. 3).

  At this time, the front surface side of the front flat portion 5011 in the Z-shaped portion 501 of the second electrode member 52 is in contact with the back surface 202 of the transmission ring body 21 in the transmission ring 20 and is not in contact with the front electrode 22 (FIG. 7 ( b)). On the other hand, the rear side of the rear flat portion 5012 in the Z-shaped portion 501 of the second electrode member 52 contacts the second rear electrode 422 provided on the surface 401 of the base ring body 41 in the base ring 40. (See FIG. 9A).

  At this time, the Z-shaped portion 501 of the second electrode member 52 is compressed in the center line direction by being sandwiched between the transmission ring 20 and the base ring 40. And the 2nd electrode member 52 and the housing | casing part 10 are facing the transmission ring 20 (transmission ring main body 21), the base ring 40 (base ring main body 41), and the space | gap.

[Connection electrode]
The 1st connection electrode 61 and the 2nd connection electrode 62 are comprised by the wire harness etc., for example. Then, one end of the first connection electrode 61 is connected to the end portion on the back side exposed to the rear internal space 10c in the linear portion 502 of the first electrode member 51, and the other end of the first connection electrode 61 is It is exposed on the back side of the casing 10. On the other hand, one end of the second connection electrode 62 is connected to an end portion on the back side exposed to the rear internal space 10 c in the linear portion 502 of the second electrode member 52, and the other end of the second connection electrode 62. Are exposed on the back side of the casing 10.

[Electrical connection structure in pressure detector]
Here, an electrical connection structure in the pressure detection device 8 of the present embodiment will be described.
(Signal path)
FIG. 11 is a diagram for explaining the electrical connection of the piezoelectric element group 30 in the pressure detection device 8. FIG. 12 is a diagram for explaining electrical connection among the piezoelectric element group 30, the front electrode 22, and the rear electrode 42. Hereinafter, an electrical connection structure in the pressure detection device 8 will be described with reference to FIGS. 11 and 12 in addition to FIGS. 1 to 10.

  First, the first connection electrode 61 is electrically connected to the first front electrode 221 of the transmission ring 20 via the first electrode member 51.

  Further, the first front electrode 221 of the transmission ring 20 is electrically connected to the positive charge output surface 301 of the first piezoelectric element 31. Further, the negative charge output surface 302 of the first piezoelectric element 31 is electrically connected to the first rear electrode 421 of the base ring 40. The first rear electrode 421 of the base ring 40 is electrically connected to the positive charge output surface 301 of the second piezoelectric element 32. Further, the negative charge output surface 302 of the second piezoelectric element 32 is electrically connected to the second front electrode 222 of the transmission ring 20. The second front electrode 222 of the transmission ring 20 is electrically connected to the positive charge output surface 301 of the third piezoelectric element 33. Further, the negative charge output surface 302 of the third piezoelectric element 33 is electrically connected to the second rear electrode 422 of the base ring 40.

  The first front electrode 221 of the transmission ring 20 is electrically connected to the positive charge output surface 301 of the sixth piezoelectric element 36. Further, the negative charge output surface 302 of the sixth piezoelectric element 36 is electrically connected to the third rear electrode 423 of the base ring 40. Further, the third rear electrode 423 of the base ring 40 is electrically connected to the positive charge output surface 301 of the fifth piezoelectric element 35. Further, the negative charge output surface 302 of the fifth piezoelectric element 35 is electrically connected to the third front electrode 223 of the transmission ring 20. Further, the third front electrode 223 of the transmission ring 20 is electrically connected to the positive charge output surface 301 of the fourth piezoelectric element 34. Further, the negative charge output surface 302 of the fourth piezoelectric element 34 is electrically connected to the second rear electrode 422 of the base ring 40.

  The second rear electrode 422 of the base ring 40 is electrically connected to the second connection electrode 62 via the second electrode member 52.

  Thus, the 1st piezoelectric element 31, the 2nd piezoelectric element 32, and the 3rd piezoelectric element 33 are connected in series in this order. The sixth piezoelectric element 36, the fifth piezoelectric element 35, and the fourth piezoelectric element 34 are connected in series in this order. The first piezoelectric element 31, the second piezoelectric element 32, and the third piezoelectric element 33, and the sixth piezoelectric element 36, the fifth piezoelectric element 35, and the fourth piezoelectric element 34 are connected in parallel. Hereinafter, an electrical path from the first connection electrode 61 to the second connection electrode 62 via the first piezoelectric element 31 to the sixth piezoelectric element 36 is referred to as a “signal path”.

(Case path)
On the other hand, in the casing unit 10, the front outer casing 11 and the pressure receiving front inner casing 12 are electrically connected. Further, in the casing unit 10, the pressure receiving front inner casing 12 and the middle casing 13 are electrically connected. Further, in the case unit 10, the front outer case 11 and the rear outer case 14 are electrically connected. Furthermore, in the housing unit 10, the rear outer housing 14 and the rear inner housing 15 are electrically connected.

  Therefore, in the casing unit 10, the front outer casing 11, the pressure receiving front inner casing 12, the middle casing 13, the rear outer casing 14, and the rear inner casing 15 are all electrically connected. . Hereinafter, an electrical path in the casing unit 10 is referred to as a “casing path”.

(Relationship between signal path and chassis path)
The signal path and the casing path are electrically insulated through the transmission ring main body 21 of the transmission ring 20, the base ring main body 41 of the base ring 40, and various gaps.

[Manufacturing method of pressure detection device]
Now, a method for manufacturing the pressure detection device 8 of the present embodiment will be described.
(Front housing manufacturing process)
In the first front case manufacturing process, first, the front outer case 11 is brought closer to the front side from the back side of the pressure receiving front inner case 12, and the pressure receiving portion 121 of the pressure receiving front inner case 12 is moved closer. The notch 111 of the front outer casing 11 is fitted into the edge 1212. Then, the front end of the front outer casing 11 (the periphery of the notch 111) and the edge end 1214 of the pressure receiving section 121 of the pressure receiving front inner casing 12 are laser-welded over the entire circumference, so that the front Get the housing. Hereinafter, a region surrounded by the front outer housing 11 and the pressure-receiving front inner housing 12 (a region that will later constitute the front internal space 10b) is referred to as the inside of the front housing.

(Transmission ring installation process)
In the next transmission ring mounting step, the transmission ring 20 is inserted into the front casing from the back side with the front surface 201 as the front side with the inside of the futon and the casing, that is, the back side facing upward. The front surface 201 of the transmission ring 20 (the side on which the front electrode 22 is not provided) is abutted against the convex portion 1212 of the pressure receiving portion 121 of the front inner housing 12. At this time, the back surface 202 (the side on which the front electrode 22 is provided) of the transmission ring 20 faces upward.

(Piezoelectric element mounting process)
In the next piezoelectric element group mounting step, the first piezoelectric elements 31 to 6 are shifted from the back side, that is, from the upper side by 60 ° counterclockwise by 60 ° to the back surface 202 of the transmission ring 20 disposed inside the front housing. The piezoelectric elements 36 are arranged side by side.

  At this time, the first piezoelectric element 31 is located on the counterclockwise downstream side of the first front electrode 221, and the second piezoelectric element 32 is located on the counterclockwise upstream side of the second front electrode 222. The element 33 is disposed in contact with a portion of the second front electrode 222 on the downstream side in the counterclockwise direction. In addition, at this time, the fourth piezoelectric element 34 is located at the upstream side of the third front electrode 223 and the fifth piezoelectric element 35 is located at the downstream side of the third front electrode 223. The six piezoelectric elements 36 are arranged in contact with the first front electrode 221 on the upstream side in the counterclockwise direction.

  At this time, the first piezoelectric element 31, the third piezoelectric element 33, the fourth piezoelectric element 34, and the sixth piezoelectric element 36 are arranged so that the positive charge output surface 301 is in contact with the front side, that is, the front electrode 22. On the other hand, the second piezoelectric element 32 and the fifth piezoelectric element 35 are arranged such that the negative charge output surface 302 is in contact with the front side, that is, the front electrode 22.

(Electrode member mounting process)
In the next electrode member attaching step, the first electrode member is formed on the rear surface 202 of the transmission ring 20 disposed inside the front housing from the rear surface side with the Z-shaped portion 501 as the front surface side and the linear portion 502 as the rear surface side. 51 and the second electrode member 52 are abutted against each other.

  At this time, in the first electrode member 51, the front surface of the front flat portion 5011 of the Z-shaped portion 501 is a portion of the back surface 202 of the transmission ring 20 that is intermediate between the sixth piezoelectric element 36 and the first piezoelectric element 31. It is hit by. As a result, the first electrode member 51 comes into contact with the first front electrode 221. At this time, the linear portion 502 of the first electrode member 51 is disposed closer to the front outer casing 11 than the pressure receiving front inner casing 12, and faces the inner peripheral surface of the front outer casing 11.

  On the other hand, in the second electrode member 52, the front surface of the front flat portion 5011 of the Z-shaped portion 501 is located at a portion of the back surface 202 of the transmission ring 20 that is intermediate between the third piezoelectric element 33 and the fourth piezoelectric element 34. It is hit. As a result, the second electrode member 52 is not in contact with any of the first front electrode 221 to the third front electrode 223. At this time, the linear portion 502 of the second electrode member 52 is disposed closer to the front outer casing 11 than the pressure-receiving front inner casing 12 and faces the inner peripheral surface of the front outer casing 11.

  As a result, the first electrode member 51 and the second electrode member 52 are disposed at positions shifted by 180 ° with the front inner housing part 122 interposed therebetween.

(Base ring mounting process)
In the next base ring mounting step, the base ring 40 is inserted into the front housing from the back side with the front surface 401 as the front side. At this time, the straight part 502 of the first electrode member 51 already attached passes through the first groove part 411 provided in the base ring 40 and the straight part of the second electrode member 52 already attached. The base ring 40 is inserted so that the shape portion 502 passes through the second groove portion 412 provided in the base ring 40. As a result, the surface of the base ring 40 on the back side of the rear flat part 5012 of the Z-shaped part 501 in the first electrode member 51 and on the back side of the rear flat part 5012 of the Z-shaped part 501 in the second electrode member 52. 401 hits.

  At this time, the first piezoelectric element 31 is located at a position upstream of the first rear electrode 421 in the clockwise direction, and the second piezoelectric element 32 is located at a position downstream of the first rear electrode 421 in the clockwise direction. Are opposed to the portions of the second rear electrode 422 on the upstream side in the clockwise direction. Further, at this time, the fourth piezoelectric element 34 is located at the site downstream of the second rear electrode 422 in the clockwise direction, and the fifth piezoelectric element 35 is located at the site upstream of the third rear electrode 423 in the clockwise direction. The elements 36 face each other on the downstream side of the third rear electrode 423 in the clockwise direction.

  At this time, the negative charge output surface 302 of the first piezoelectric element 31, the third piezoelectric element 33, the fourth piezoelectric element 34, and the sixth piezoelectric element 36 faces the rear side, that is, the rear electrode 42. On the other hand, in the second piezoelectric element 32 and the fifth piezoelectric element 35, the positive charge output surface 301 faces the back side, that is, the rear electrode 42.

  Here, the height of the Z-shaped portion 501 in the first electrode member 51 and the second electrode member 52 is slightly smaller than the height of the first piezoelectric element 31 to the sixth piezoelectric element 36 (piezoelectric body 300) as described above. Is set to be large. For this reason, at this time, the first piezoelectric element 31 to the sixth piezoelectric element 36 and the surface 401 of the base ring 40 hardly contact each other.

(Middle housing installation process)
In the next middle casing attaching step, the middle casing 13 is inserted into the front casing from the back side with the large inner diameter portion 133 as the front side. At this time, the linear portion 502 of the first electrode member 51 passes through the first through hole 131 of the middle casing 13, and the linear portion 502 of the second electrode member 52 is the second portion of the middle casing 13. The middle casing 13 is inserted so as to pass through the through hole 132. As a result, the front surface of the middle casing 13 abuts against the back side of the base ring 40, that is, the back surface 402. At this time, the large inner diameter portion 133 of the inner peripheral surface of the middle housing 13 faces the large outer diameter portion 1221 of the outer peripheral surface of the front inner housing portion 122, and the outer periphery of the front inner housing portion 122 is slightly out of the outer peripheral surface. The small inner diameter portion 134 of the inner peripheral surface of the middle casing 13 is opposed to the diameter portion 1222.

  Subsequently, a predetermined pressing force is applied from the back side of the middle casing 13. Accordingly, the Z-shaped portion 501 of the first electrode member 51 and the second electrode member 52 sandwiched between the transmission ring 20 and the base ring 40 from the middle housing 13 through the base ring 40 is centered. Shrink in the line direction. As a result, the back side of the first to sixth piezoelectric elements 31 to 36 comes into contact with the surface 401 of the base ring 40. At this time, the first piezoelectric element 31 and the second piezoelectric element 32 are on the first rear electrode 421, the third piezoelectric element 33 and the fourth piezoelectric element 34 are on the second rear electrode 422, the fifth piezoelectric element 35 and the sixth piezoelectric element. The elements 36 are in contact with the third rear electrode 423, respectively.

  In this state, the middle casing 13 is fixed to the front casing by laser welding the front inner casing section 122 and the middle casing 13 of the pressure receiving front inner casing 12 over the entire circumference. Further, in the front internal space 10b formed between the front case and the middle case 13, the transmission ring 20, the piezoelectric element group 30, the base ring 40, the first electrode member 51, and the second electrode member 52 ( The Z-shaped portion 501) is fixed in a positioned state. At this time, a predetermined load (preload) is applied to each of the first piezoelectric element 31 to the sixth piezoelectric element 36 constituting the piezoelectric element group 30.

(Connecting electrode mounting process)
In the next connection electrode attachment step, the first connection electrode 61 is attached to an end portion of the linear portion 502 of the first electrode member 51 that protrudes from the first through hole 131 of the middle housing 13 to the back side. In addition, the second connection electrode 62 is attached to an end portion of the linear portion 502 of the second electrode member 52 that protrudes from the second through hole 132 of the middle housing 13 to the back side. Below, what was obtained through the connection electrode attachment process from the front housing | casing preparation process is called an intermediate structure.

(Rear housing manufacturing process)
In the next rear casing manufacturing step, the rear inner casing 15 is inserted from the front side with the middle outer diameter section 153 as the rear side, with respect to the rear outer casing 14 having the large outer diameter section 141 as the front side. A large outer diameter portion 152 provided on the outer peripheral surface of the rear inner housing 15 and a middle outer portion are formed on the step between the large inner diameter portion 145 and the small inner diameter portion 146 provided on the inner peripheral surface of the rear outer housing 14. A step with the diameter portion 153 is abutted. As a result, a rear casing in which the rear inner casing 15 is fitted into the rear outer casing 14 is obtained. In the following description, a part surrounded by the rear outer casing 14 and the rear inner casing 15 (a part that will later become the rear internal space 10c) is referred to as the interior of the rear casing.

(Rear housing installation process)
In the next rear case mounting step, first, the rear case is abutted from the back side of the intermediate structure with the middle case 13 as the back side, with the inside of the rear case as the front side. At this time, the front-side end of the rear outer casing 14 in the rear casing abuts on the rear-side end of the front outer casing 11 in the intermediate structure. At this time, the front end of the rear inner casing 15 in the rear casing comes into contact with the rear end of the middle casing 13 in the intermediate structure. At this time, the rear-side ends of the first electrode member 51 and the second electrode member 52 provided in the intermediate structure are the rear internal space 10c formed between the middle casing 13 and the rear casing. Placed inside. In this state, the end on the back side of the front outer casing 11 of the intermediate structure and the end on the front side of the rear outer casing 14 of the rear casing are laser-welded over the entire circumference to detect pressure. Device 8 is obtained.

[Injector unit manufacturing method]
Thereafter, the pressure detection device 8 is attached to the tip portion 7 b of the fuel injection device 7. More specifically, the pressure detection device 8 is attached to the fuel injection device 7 by passing the tip portion 7b of the fuel injection device 7 through the opening 10a provided in the pressure detection device 8, and the pressure detection device. The first connection electrode 61 and the second connection electrode 62 provided in 8 are respectively connected to two external electrodes (not shown) provided in the fuel injection device 7. Thus, the injector unit 6 is obtained.

[Pressure detection operation by pressure detector]
Next, the pressure detection operation of the pressure detection device 8 in the injector unit 6 attached to the internal combustion engine 1 will be described.

  A variation in combustion pressure generated in the combustion chamber C is a piezoelectric element group 30 sandwiched between the transmission ring 20 and the base ring 40 via the pressure receiving portion 121 of the pressure receiving front inner housing 12 and the transmission ring 20. Act on. In this example, the piezoelectric element group 30 includes a first piezoelectric element 31 to a sixth piezoelectric element 36 arranged at equal intervals in the circumferential direction, and each of the first piezoelectric element 31 to the sixth piezoelectric element 36 includes A charge corresponding to the pressure is generated. The charges generated by the first piezoelectric element 31 to the sixth piezoelectric element 36 are used as a charge signal (an example of a detection signal) as a signal path, that is, the front electrode 22 provided in the transmission ring 20, the first electrode member 51, and the like. It is transmitted to the fuel injection device 7 via the first connection electrode 61, the rear electrode 42, the second electrode member 52, and the second connection electrode 62. The charge signal transmitted to the fuel injection device 7 is further transmitted to a control device (not shown) that controls the operation of the internal combustion engine 1. Note that the control device performs control of the fuel supply amount by the fuel injection device 7, control of the ignition timing by the spark plug 5, and the like based on the received charge signal.

  Here, the housing part 10 provided in the pressure detection device 8 is in a state where it can come into contact with the outer peripheral surface of the main body part 7 a and the tip part 7 b of the fuel injection device 7 that constitutes the injector unit 6 together with the pressure detection device 8. . And when these main-body parts 7a and the front-end | tip part 7b are formed with the metal, since the outer peripheral surface of the front-end | tip part 7b is fastened by the cylinder head 4 made from metal, the fuel-injection apparatus 7 is sent from the cylinder head 4 to it. Thus, noise may enter the casing 10 of the pressure detection device 8. However, in the pressure detection device 8 of the present embodiment, the signal path and the casing path by the casing section 10 are insulated by having the above-described configuration. This makes it difficult for noise entering from the cylinder head 4 side to be superimposed on the charge signal output to the fuel injection device 7 via the signal path.

[Summary]
As described above, in the present embodiment, the pressure receiving front inner housing 12 in which the pressure receiving portion 121 that receives pressure from the combustion chamber C in the pressure detection device 8 is integrated with the front inner housing portion 122, and the front outer housing. The body 11 is connected by laser welding to constitute a front housing that accommodates the piezoelectric element group 30 inside (in the front internal space 10b). By adopting this configuration, it is possible to suppress deformation in the obtained front casing as compared with a case where a configuration in which the pressure receiving portion 121 and the front inner casing portion 122 are separated in the initial state is adopted. it can. And it becomes possible to reduce the error of the pressure transmitted via the pressure receiving part 121 to the piezoelectric element group 30 accommodated in the inside of a front housing in connection with the deformation | transformation in a front housing | casing being suppressed. Further, the durability of the housing 10 (particularly the front housing) can be improved as compared with the case where connection (welding) is performed on the inner side and the outer side of the pressure receiving unit 121.

  Further, in the present embodiment, the front inner space 10b is formed in the housing portion 10 using the front housing and the middle housing 13 described above, and the piezoelectric element disposed in the front inner space 10b is formed. A preload was applied to the element group 30. Thereby, the pressure which the piezoelectric element group 30 receives can be stabilized.

  Further, in the present embodiment, the transmission ring main body 21 is disposed between the metal pressure receiving portion 121 and the piezoelectric element group 30 in the front internal space 10b, and the metal middle casing 13 and the piezoelectric element group are arranged. The base ring main body 41 is arranged between 30 and 30. Thereby, a stable preload can be applied to each of the six piezoelectric elements (the first piezoelectric element 31 to the sixth piezoelectric element 36) constituting the piezoelectric element group 30.

  Furthermore, in the present embodiment, the casing path by the casing section 10 including the front casing and the signal path including the piezoelectric element group 30 are separated by electrical insulation. Thereby, it is possible to suppress noise from being superimposed on the electrification signal from the piezoelectric element group 30 from the outside of the housing unit 10 via the housing unit 10.

In the present embodiment, the front case is configured using the front outer case 11 and the pressure receiving front inner case 12 in which the pressure receiving part 121 and the front inner case part 122 are integrated. This is due to the following reason.
It is possible to configure the front case using the front outer case 11 provided with the pressure receiving part 121 and the front inner case part 122 obtained by removing the pressure receiving part 121 from the pressure receiving front inner case 12. However, in this case, it is difficult to ensure the dimensional accuracy of the front casing after welding because the inside of the opening 10a has to be welded.
For this reason, in the present embodiment, the pressure receiving front inner casing 12 formed by integrating the pressure receiving section 121 and the front inner casing section 122 is used.

[Others]
In the present embodiment, the piezoelectric element group 30 provided in the pressure detection device 8 is configured by the six piezoelectric bodies 300. However, the present invention is not limited to this. In the present embodiment, the plurality of piezoelectric bodies 300 constituting the piezoelectric element group 30 are arranged at equal intervals in the circumferential direction. However, the present invention is not limited to this. Good. In the present embodiment, the piezoelectric element group 30 is configured by a plurality (six in this case) of piezoelectric bodies 300, but a single piezoelectric body 300 may be used. In this case, it is desirable to use the annular piezoelectric body 300.

  In the present embodiment, the case where the injector unit 6 is configured by combining the pressure detection device 8 with the fuel injection device 7 has been described as an example. However, the present invention is not limited to this. For example, an ignition plug unit (an example of an internal combustion engine component) may be configured by combining the above-described pressure detection device 8 with the spark plug 5 (an example of a functional component) illustrated in FIG.

Furthermore, in this embodiment, the case where a piezoelectric element is used as a pressure detection element has been described as an example. However, the present invention is not limited to this, and for example, a strain gauge, a separated electrode, or the like may be used. .
In the present embodiment, the pressure detection target by the pressure detection device 8 is the internal combustion engine 1, but the present invention is not limited to this and may be other than the internal combustion engine 1.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Cylinder block, 3 ... Piston, 4 ... Cylinder head, 5 ... Spark plug, 6 ... Injector unit, 7 ... Fuel injection apparatus, 8 ... Pressure detection apparatus, 10 ... Housing part, 11 ... Front Outer housing, 12 ... Pressure receiving front inner housing, 13 ... Middle housing, 14 ... Rear outer housing, 15 ... Rear inner housing, 20 ... Transmission ring, 21 ... Transmission ring body, 22 ... Front electrode, 30 ... Piezoelectric element group 31 ... first piezoelectric element 32 ... second piezoelectric element 33 ... third piezoelectric element 34 ... fourth piezoelectric element 35 ... fifth piezoelectric element 36 ... sixth piezoelectric element 40 ... base Ring, 41 ... Base ring body, 42 ... Rear electrode, 51 ... First electrode member, 52 ... Second electrode member, 61 ... First connection electrode, 62 ... Second connection electrode

Claims (5)

A cylindrical housing having an outer housing and an inner housing housed inside the outer housing;
A pressure receiving member configured integrally with the inner housing and attached to the outer housing to receive pressure from the outside;
A pressure detection device including a detection element provided between the outer casing and the inner casing and outputting a detection signal corresponding to the pressure received from the pressure receiving member.   2. The apparatus according to claim 1, further comprising: another casing that is attached to the casing and sandwiches the detection element between the pressure receiving member and applies a predetermined preload to the detection element. Pressure detection device. A transmission member provided between the pressure receiving member and the detection element, and transmitting the pressure received by the pressure reception member to the detection element;
The pressure detection device according to claim 2, further comprising an applying member that is provided between the other casing and the detection element and applies a preload to the detection element together with the other casing. . A signal path for outputting a detection signal from the detection element;
The pressure detection device according to claim 2, wherein the casing, the pressure receiving member, the other casing, and the signal path are electrically insulated. Functional parts that function in the combustion operation of fuel in the combustion chamber of the internal combustion engine;
A pressure detection device that is attached to a portion of the functional component facing the combustion chamber and detects the pressure in the combustion chamber;
The pressure detection device includes:
An outer casing and an inner casing accommodated inside the outer casing, and a cylindrical casing in which at least a part of the functional component is accommodated inside the inner casing;
A pressure receiving member configured integrally with the inner casing and attached to the outer casing, and receiving pressure from the combustion chamber;
A component for an internal combustion engine including a detection element that is provided between the outer casing and the inner casing and outputs a detection signal corresponding to the pressure received from the pressure receiving member.

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