JP5936878B2 - Pressure detection device - Google Patents

Description

  The present invention relates to a pressure detection device.

2. Description of the Related Art Conventionally, a pressure detection device that is mounted on an internal combustion engine and detects the pressure in a combustion chamber is known.
For example, in Cited Document 1, a piezoelectric element that converts pressure into an electric signal, a circuit board unit that processes an electric signal obtained from the piezoelectric element, and the piezoelectric element and the circuit board unit are electrically connected within the housing. A pressure detection device including a lead portion (conductive member) is described. And in this pressure detection apparatus, the lead part is supported by fitting the guide pipe (conductive member accommodating part) in which the lead part was inserted in the hole provided in the housing.

JP 2008-286589 A

However, in such a pressure detection device, in order to fit the guide pipe (conducting member accommodating portion) into the hole of the housing, it is necessary to increase both the accuracy of the shape and dimensions of the hole of the housing and the guide pipe. It was.
An object of this invention is to implement | achieve the attachment of the conduction member accommodating part with respect to the hole of a housing by fitting easily.

The pressure detection device of the present invention is disposed on the rear end side of the diaphragm, a cylindrical housing provided with a hole extending in the axial direction from the front end toward the rear end, a diaphragm provided on the front end side of the housing, A piezoelectric element that performs output in accordance with the pressure acting through the diaphragm, a conductive member that conducts the output from the piezoelectric element toward the rear end side, and the conductive member is housed in the axial direction and in the axial direction And a conductive member accommodating portion that is fitted and attached to the hole of the housing, and the conductive member accommodating portion protrudes from the outer peripheral surface of the conductive member accommodating portion and the conductive member accommodating portion. lined up circumferentially spaced, respectively provided along the axial direction of the conductive member receiving portion, along the axial direction against the inner peripheral surface of said hole in said housing A first projection group including a plurality of first protrusions for supporting the conductive member receiving portion by touch, are spaced apart on the rear end side from the first protruding portion group, the outer peripheral surface of the conductive member receiving portion Sort at intervals in the circumferential direction of the conductive member receiving portion as to protrude from each is provided along the axial direction of the conductive member receiving portion, the axial direction against the inner peripheral surface of said hole in said housing And a second convex portion group including a plurality of second convex portions supporting the conductive member accommodating portion together with the plurality of first convex portions.

In such a pressure detection device, the plurality of first convex portions in the first convex portion group are spaced apart in the circumferential direction of the conductive member accommodating portion at the same position in the axial direction of the conductive member accommodating portion. The plurality of second convex portions in the second convex portion group are arranged at intervals in the circumferential direction of the conductive member accommodating portion at the same other position in the axial direction of the conductive member accommodating portion. It can be characterized by that. Thereby, the vibration to the direction which cross | intersects the axial direction of a conduction member accommodating part can be suppressed.
Further, in such a pressure detection device, the conductive member housing portion has a cylindrical shape, and the first convex portion group is arranged in four circumferential directions of the conductive member housing portion at intervals of 90 degrees. The second convex portion group includes four second convex portions arranged at intervals of 90 degrees in the circumferential direction of the conductive member accommodating portion, and each of the first convex portions and each of the second convex portions. The protrusions may be provided so as to overlap each other when viewed from the axial direction. Thereby, while being able to suppress the vibration to the direction which cross | intersects the axial direction of a conduction member accommodating part, a conduction member accommodating part can be more easily attached with respect to the hole of a housing.
Furthermore, the plurality of first protrusions are located at the front end of the first protrusion, and the height from the outer peripheral surface of the conductive member housing portion gradually increases from the front end side toward the rear end side. And a flat portion extending from the rear end portion of the inclined portion along the axial direction and having a substantially constant height from the outer peripheral surface of the conductive member housing portion to the rear end side. The plurality of second protrusions are located at the front end of the second protrusion, and the height from the outer peripheral surface of the conductive member housing portion gradually increases from the front end side toward the rear end side. And a flat portion extending from the rear end portion of the inclined portion along the axial direction and having a substantially constant height from the outer peripheral surface of the conductive member housing portion to the rear end side. Can be characterized. Thereby, the conductive member accommodating portion can be more easily attached to the hole of the housing .

From another point of view, the pressure detection device of the present invention includes a cylindrical housing in which a hole extending in the axial direction from the front end toward the rear end is formed, the diaphragm provided on the front end side of the housing, A piezoelectric element that is disposed on the rear end side of the diaphragm and performs output according to the pressure acting through the diaphragm, a conductive member that conducts output from the piezoelectric element toward the rear end side, and the conductive member inside housing the member, parallel beauty at intervals in the circumferential direction as well as projecting from the outer peripheral surface, each comprising a conductive member receiving portion having a plurality of convex portions extending along the axial direction, said conductive member containing portion The plurality of convex portions of the conductive member accommodating portion are deformed by contacting the inner peripheral surface of the hole and press the inner peripheral surface by elastic force. Shi And said that you are.

  According to the present invention, it is possible to facilitate attachment of the conductive member accommodating portion to the hole of the housing by fitting.

1 is a schematic configuration diagram of an internal combustion engine according to an embodiment. It is an enlarged view of the II section of the pressure detection apparatus shown in FIG. It is a schematic block diagram of a pressure detection apparatus. It is sectional drawing of the IV-IV part of the pressure detection apparatus shown in FIG. It is an enlarged view of the V section of the pressure detection apparatus shown in FIG. It is an enlarged view of VI part of the pressure detection apparatus shown in FIG. It is a figure for demonstrating the structure of the front-end | tip part in the 2nd housing before a signal processing part is inserted, and the signal processing part before being inserted in a 2nd housing. It is sectional drawing of the 2nd housing and signal processing part which are shown in FIG. It is the figure which showed an example of the structure of the front-end | tip part in the signal processing part which concerns on other embodiment. It is the figure which showed an example of the structure of the front-end | tip part in the signal processing part which concerns on other embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of an internal combustion engine 1 according to the present embodiment. 2 is an enlarged view of the II part of the pressure detection device 5 shown in FIG.
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 mounted on the cylinder head 4 to detect the pressure in the combustion chamber C, and a control device that controls the operation of the internal combustion engine 1 based on the pressure detected by the pressure detection device 5. 6, an electric signal is transmitted between the pressure detection device 5 and the control device 6, and between the pressure detection device 5 and the control device 6, which is interposed between the pressure detection device 5 and the cylinder head 4 and maintains the airtightness in the combustion chamber C. A transmission cable 8.

  As shown in FIG. 2, the cylinder head 4 is formed with a communication hole 4 a that communicates the combustion chamber C with the outside. From the combustion chamber C side, the communication hole 4a has a hole diameter larger than the first hole part 4b, the inclined part 4c whose diameter gradually increases from the hole diameter of the first hole part 4b, and the hole diameter of the first hole part 4b. A large second hole 4d. A female screw 4e into which a male screw 332a of the housing 30 (described later) formed in the pressure detection device 5 is screwed is formed on the surrounding wall forming the second hole 4d.

Below, the pressure detection apparatus 5 is explained in full detail.
FIG. 3 is a schematic configuration diagram of the pressure detection device 5. 4 is a cross-sectional view of the IV-IV portion of the pressure detection device 5 shown in FIG. FIG. 5 is an enlarged view of a V portion of the pressure detection device 5 shown in FIG. FIG. 6 is an enlarged view of a VI part of the pressure detection device 5 shown in FIG.
The pressure detection device 5 includes a sensor unit 100 having a piezoelectric element 10 that converts the pressure in the combustion chamber C into an electric signal, a signal processing unit 200 that processes an electric signal from the sensor unit 100, and a signal processing unit 200. Holding member 300. When the pressure detection device 5 is mounted on the cylinder head 4, the diaphragm head 40 (described later) of the sensor unit 100 is inserted into the communication hole 4 a formed in the cylinder head 4 first. In the following description, the left side of FIG. 4 is the front end side of the pressure detection device 5, and the right side is the rear end side of the pressure detection device 5.

First, the sensor unit 100 will be described.
The sensor unit 100 includes a piezoelectric element 10 that converts received pressure into an electrical signal, and a housing 30 that is cylindrical and in which a cylindrical hole that accommodates the piezoelectric element 10 and the like is formed. . Hereinafter, the center line direction of the cylindrical hole formed in the housing 30 is simply referred to as a center line direction.
The sensor unit 100 is provided so as to close the opening on the distal end side of the housing 30, and is provided between the diaphragm head 40 on which the pressure in the combustion chamber C acts, and between the diaphragm head 40 and the piezoelectric element 10. The first electrode unit 50 and the second electrode unit 55 disposed on the opposite side of the piezoelectric element 10 from the first electrode unit 50 are provided.
In addition, the sensor unit 100 is provided with an insulating ring 60 made of alumina ceramic that electrically insulates the second electrode unit 55 and a rear end side of the insulating ring 60, and a covering member described later of the signal processing unit 200. 23, and a coil spring 70 interposed between the second electrode portion 55 and the conductive member 22 described later.

  The piezoelectric element 10 has a piezoelectric body that exhibits the piezoelectric action of the piezoelectric longitudinal effect. The piezoelectric longitudinal effect refers to the action of generating charges on the surface of the piezoelectric body in the direction of the charge generation axis when an external force is applied to the stress application axis in the same direction as the charge generation axis of the piezoelectric body. The piezoelectric element 10 according to the present embodiment is housed in the housing 30 so that the center line direction is the direction of the stress application axis.

  Next, a case where the piezoelectric lateral effect is used for the piezoelectric element 10 will be illustrated. The piezoelectric transverse effect is an action in which charges are generated on the surface of the piezoelectric body 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. A plurality of thinly formed piezoelectric bodies may be laminated, and by laminating in this way, the charge generated in the piezoelectric bodies can be efficiently collected to increase the sensitivity of the sensor. Examples of the piezoelectric single crystal include the use of a langasite crystal (a langasite, langagate, langanite, LGTA) having a piezoelectric longitudinal effect and a piezoelectric transverse effect, quartz, gallium phosphate, and the like. In the piezoelectric element 10 of the present embodiment, a langasite single crystal is used as the piezoelectric body.

As shown in FIG. 5, the housing 30 includes a first housing 31 provided on the front end side and a second housing 32 provided on the rear end side.
The first housing 31 is a thin-walled cylindrical member having a cylindrical hole 310 formed therein so that the diameter thereof is gradually changed from the front end side to the rear end side. On the outer peripheral surface of the first housing 31, a protruding portion 315 protruding from the outer peripheral surface is provided in the central portion in the center line direction over the entire region in the circumferential direction.
The hole 310 includes a first hole 311 and a second hole 312 having a diameter larger than the diameter of the first hole 311 formed in order from the front end side to the rear end side. The protrusion 315 has an inclined surface 315a whose diameter gradually increases from the front end side to the rear end side at the front end portion, and a vertical surface 315b perpendicular to the center line direction at the rear end portion.

As shown in FIG. 4, the second housing 32 is a cylindrical member in which a cylindrical hole 320 is formed so that the diameter thereof is gradually changed from the front end side to the rear end side. The outer peripheral surface 330 is formed outside so as to have a diameter that is gradually changed from the front end side to the rear end side.
The hole 320 includes a first cylindrical hole 321 having a first hole diameter formed in order from the front end side to the rear end side, and a second hole diameter Dh2 smaller than the first hole diameter (FIGS. 7 and 8 described later). A second cylindrical hole 322 having a third hole diameter Dh3 (see FIGS. 7 and 8) larger than the second hole diameter Dh2, and a third hole diameter Dh3. A fourth cylindrical hole 324 having a large fourth hole diameter Dh4 (see FIGS. 7 and 8) and a fifth cylindrical hole 325 having a fifth hole diameter larger than the fourth hole diameter Dh4 are configured. .
The first hole diameter of the first cylindrical hole 321 is such that the front end portion of the second housing 32 is fitted (press-fit) to the rear end portion of the first housing 31 with an interference fit. It is set to be equal to or less than the diameter of the outer peripheral surface of 31.

The outer peripheral surface 330 has a first outer peripheral surface 331, a second outer peripheral surface 332 having an outer diameter larger than the outer diameter of the first outer peripheral surface 331, and a second outer peripheral surface 332 from the front end side to the rear end side. Than the outer diameter of the third outer peripheral surface 333, the fourth outer peripheral surface 334 having an outer diameter larger than the outer diameter of the third outer peripheral surface 333, and the outer diameter of the fourth outer peripheral surface 334. And a fifth outer peripheral surface 335 having a small outer diameter.
A male screw 332 a that is screwed into the female screw 4 e of the cylinder head 4 is formed at the distal end portion of the second outer peripheral surface 332. A first seal member 71, which will be described later, is fitted into the third outer peripheral surface 333 with a clearance fit, and the dimensional tolerance between the outer diameter of the third outer peripheral surface 333 and the inner diameter of the first seal member 71 is, for example, zero. To 0.2 mm. The rear end portion of the fourth outer peripheral surface 334 is formed as a regular hexagonal column having six chamfers at equal intervals in the circumferential direction. When the pressure detecting device 5 is fastened to the cylinder head 4, the portion formed in the regular hexagonal column is a portion into which a tightening tool is fitted and a rotational force applied to the tool is transmitted. A concave portion 335a that is recessed from the outer peripheral surface is formed over the entire circumference in the center portion of the fifth outer peripheral surface 335 in the center line direction.

  Further, as shown in FIG. 6, the second housing 32 is a transition portion from the fourth cylindrical hole 324 to the fifth cylindrical hole 325 (see FIG. 4), and the tip portion in the fifth cylindrical hole 325. Is provided with an abutting surface 340 against which an end surface on the front end side of a substrate covering portion 232 of a covering member 23 (see FIG. 4) described later of the signal processing unit 200 abuts. On the abutting surface 340, a pin recess 340a into which a second connection pin 21b of a printed wiring board 210 of the signal processing unit 200 described later is inserted is formed.

  Since the first housing 31 and the second housing 32 exist in a position close to the combustion chamber C, it is preferable to manufacture the first housing 31 and the second housing 32 by using a material that can withstand at least a use temperature environment of −40 to 350 [° C.]. Specifically, it is desirable to use a stainless steel material having high heat resistance, for example, JIS standard SUS630, SUS316, SUS430 or the like. In this embodiment, SUS430 is used as the first housing 31 and the second housing 32. Used.

As shown in FIG. 5, the diaphragm head 40 has a cylindrical cylindrical portion 41 and an inner portion 42 formed inside the cylindrical portion 41.
The rear end portion of the cylindrical portion 41 is fitted (press-fitted) into the front end portion of the first housing 31 of the housing 30 with an interference fit, and enters the inside of the front end portion. It has the same shape as 31a, and has an abutting surface 41b against which this end surface 31a abuts when fitted.
The inner part 42 is a disk-shaped member provided so as to close the opening on the front end side in the cylindrical part 41, and the central part of the rear end side surface protrudes from this surface to the piezoelectric element 10 side. A portion 42a is provided. In addition, a concave portion 42b that is recessed from the surface toward the piezoelectric element 10 is provided at the center of the inner portion 42 on the front surface side.
The material of the diaphragm head 40 is preferably made of an alloy having high elasticity and excellent durability, heat resistance, touch resistance, and the like because it exists in the combustion chamber C at a high temperature and a high pressure. For example, SUH660 can be exemplified.

The first electrode unit 50 is a columnar member formed so that the diameters are gradually changed from the front end side to the rear end side. From the radius of the first columnar part 51 and the first columnar part 51 And a second cylindrical portion 52 having a large radius. The outer diameter of the first cylindrical part 51 is smaller than the inner diameter of the entry part 41 a of the diaphragm head 40, and the outer diameter of the second cylindrical part 52 is substantially the same as the hole diameter of the first hole 311 of the first housing 31. is there. The end surface on the front end side of the first cylindrical portion 51 is a protrusion 42a of the inner portion 42 of the diaphragm head 40, the end surface on the rear end side of the second cylindrical portion 52 is a surface on the front end side of the piezoelectric element 10, and They are arranged to contact each other. When the outer peripheral surface of the second cylindrical portion 52 is in contact with the inner peripheral surface of the first housing 31 and / or the end surface on the distal end side of the first cylindrical portion 51 is in contact with the diaphragm head 40, the piezoelectric element 10 is electrically connected to the housing 30.
The first electrode portion 50 applies pressure in the combustion chamber C to the piezoelectric element 10, and the end surface on the rear end side of the second cylindrical portion 52 that is the end surface on the piezoelectric element 10 side is the piezoelectric element 10. It is formed in a size that can push the entire end face. The first electrode portion 50 has both end surfaces in the center line direction formed on smooth surfaces so that the pressure received from the diaphragm head 40 can be applied to the piezoelectric element 10 evenly. They are provided substantially parallel to each other along a plane orthogonal to the direction.
An example of the material of the first electrode unit 50 is stainless steel.

The second electrode portion 55 is a cylindrical member, and is disposed such that the end surface on the front end side contacts the end surface on the rear end side of the piezoelectric element 10 and the end surface on the rear end side contacts the insulating ring 60. . A columnar projecting portion 55 a that projects from the end surface to the rear end side is provided on the end surface on the rear end side of the second electrode portion 55. The protrusion 55a has a base end portion on the end face side and a tip end portion having an outer diameter smaller than the outer diameter of the base end portion. The outer diameter of the protruding portion 55a is set smaller than the inner diameter of the insulating ring 60, and the length of the protruding portion 55a is set longer than the width of the insulating ring 60 (the length in the center line direction). The tip is exposed from the insulating ring 60. The second electrode portion 55 is a member that acts so as to apply a certain load to the piezoelectric element 10 with the first electrode portion 50, and the end surface on the piezoelectric element 10 side (tip side) is The entire surface of the end face on the rear end side of the piezoelectric element 10 is formed so as to be able to be pressed, and is formed on a smooth surface and a plane parallel to the end face on the rear end side of the piezoelectric element 10. The outer diameter of the second electrode portion 55 is set to be smaller than the hole diameter of the second hole 312 of the first housing 31, and the outer peripheral surface of the second electrode portion 55 and the first housing 31 There is a gap between the inner peripheral surface.
The material of the second electrode portion 55 can be exemplified by stainless steel.

  The insulating ring 60 is a cylindrical member formed of alumina ceramic or the like, and the inner diameter (hole diameter at the center) is slightly larger than the outer diameter of the base end portion of the protruding portion 55a of the second electrode portion 55, The outer diameter is set to be approximately the same as the hole diameter of the second hole 312 of the first housing 31. The second electrode portion 55 is arranged with the protruding portion 55 a being inserted into the central hole of the insulating ring 60, so that the center position of the second electrode portion 55 and the second hole of the first housing 31 are arranged. It arrange | positions so that the center of 312 may become the same.

The support member 65 has a cylindrical member in which a plurality of cylindrical holes 650 having different diameters are formed from the front end side to the rear end side, and the diameter of the outer peripheral surface is the same from the front end side to the rear end side. It is.
The holes 650 are formed in order from the front end side to the rear end side, based on the first hole 651, the second hole 652 having a larger diameter than the first hole 651, and the hole diameter of the second hole 652. And a third hole 653 having a larger hole diameter. The hole diameter of the first hole 651 is larger than the outer diameter of the base end portion of the protruding portion 55 a of the second electrode portion 55, and the protruding portion 55 a is exposed to the inside of the support member 65. The hole diameter of the second hole 652 is larger than the outer diameter of the distal end portion of the conductive member 22 of the signal processing unit 200 described later. The hole diameter of the third hole 653 is smaller than the outer diameter of the end portion on the front end side of the covering member 23 of the signal processing unit 200 described later, and this covering member 23 is stuck to the surrounding wall forming the third hole 653. Mated with a fit. Thereby, the support member 65 functions as a member that supports the end portion of the covering member 23.

  The coil spring 70 has an inner diameter that is equal to or larger than the outer diameter of the distal end portion of the protruding portion 55a of the second electrode portion 55 and smaller than the outer diameter of the proximal end portion, and the outer diameter is the diameter of the insertion hole 22a of the conductive member 22 described later. Smaller than. The distal end portion of the protruding portion 55a of the second electrode portion 55 is inserted inside the coil spring 70, and the coil spring 70 is inserted into an insertion hole 22a of the conductive member 22 described later. The length of the coil spring 70 is set to a length that can be interposed in a compressed state between the second electrode portion 55 and the conductive member 22. As a material of the coil spring 70, an alloy having high elasticity and excellent durability, heat resistance, touch resistance and the like may be used. Further, it is preferable to increase electrical conduction by applying gold plating to the surface of the coil spring 70.

Next, the signal processing unit 200 will be described.
As shown in FIGS. 3 and 4, the signal processing unit 200 is generated in the piezoelectric element 10 and the circuit board unit 21 that at least amplifies an electric signal that is a weak charge obtained from the piezoelectric element 10 of the sensor unit 100. A rod-shaped conductive member 22 that guides electric charges to the circuit board portion 21, a cover member 23 that covers the circuit board portion 21, the conductive member 22, and the like, and an O-ring 26 that seals the circuit board portion 21 and the like are provided.

  The circuit board unit 21 includes a printed wiring board 210 on which electronic components constituting a circuit for amplifying a weak charge obtained from the piezoelectric element 10 of the sensor unit 100 are mounted. A first connection pin 21a for electrically connecting a rear end portion of the conductive member 22 and a second connection pin 21b for grounding and positioning are soldered to the front end portion of the printed wiring board 210. Connected by. Further, three third connection pins 21c that are electrically connected to the control device 6 via the connector 8a at the front end of the transmission cable 8 are connected to the rear end of the printed wiring board 210 by soldering or the like. ing. The three third connection pins 21 c are used for supplying a power supply voltage and a GND voltage from the control device 6 to the printed wiring board 210 and for supplying an output voltage from the printed wiring board 210 to the control device 6, respectively.

  The conductive member 22 is a rod-shaped (columnar) member, and an insertion hole 22a into which the distal end portion of the protruding portion 55a of the second electrode portion 55 is inserted is formed at the distal end portion. The rear end portion of the conductive member 22 is electrically connected to the printed wiring board 210 of the circuit board portion 21 via a conductive wire. Examples of the material of the conductive member 22 include brass and beryllium copper. In this case, brass is desirable from the viewpoint of workability and cost. On the other hand, beryllium copper is desirable from the viewpoints of electrical conductivity, high temperature strength, and reliability.

  The covering member 23 includes a conductive member covering portion 231 as an example of a conductive member accommodating portion that covers the outer periphery of the conductive member 22, a substrate covering portion 232 that covers the side surface and the lower surface of the printed wiring board 210 of the circuit board portion 21, and a printed wiring And a connector portion 233 that covers the periphery of the third connection pin 21c connected to the substrate 210 and into which the connector 8a at the tip of the transmission cable 8 is fitted.

As shown in FIG. 3, the conductive member covering portion 231 (see FIG. 4) extends along the center line direction and covers the conductive member 22 so that the front end portion of the conductive member 22 is exposed.
Further, the conductive member covering portion 231 is composed of a plurality of cylindrical portions so that the outer diameters are gradually changed from the front end side to the rear end side. Specifically, from the front end side to the rear end side, a first cylindrical portion 241 having a first outer diameter and a second outer diameter Do2 larger than the first outer diameter (see FIG. 8 described later). A second cylindrical portion 242 having a third cylindrical portion 243 having a third outer diameter Do3 (see FIG. 8) larger than the second outer diameter Do2, and a fourth larger than the third outer diameter Do3. A fourth cylindrical portion 244 having an outer diameter Do4 (see FIG. 8) is formed side by side.
The first outer diameter of the first cylindrical portion 241 is formed larger than the hole diameter of the third hole 653 of the support member 65. As a result, the leading end portion of the conductive member covering portion 231 is fitted (press-fit) to the surrounding wall forming the third hole 653 of the support member 65 with an interference fit.

As shown in FIG. 3, the conductive member covering portion 231 (see FIG. 4) is provided with a plurality of convex portions 250 that protrude from the outer peripheral surface of the conductive member covering portion 231 and each extend in the center line direction. . In the present embodiment, the convex portion 250 is provided on the first convex portion 251 provided at the distal end portion of the second cylindrical portion 242 of the conductive member covering portion 231 and the fourth cylindrical portion 244 of the conductive member covering portion 231. The second convex portion 252 is provided. In the present embodiment, a plurality of first convex portions 251 constitute a first convex portion group, and a plurality of second convex portions 252 constitute a second convex portion group.
In this example, four first convex portions 251 are provided at intervals of 90 degrees along the circumferential direction on the outer peripheral surface of the second cylindrical portion 242. Further, four second convex portions 252 are provided at intervals of 90 degrees along the circumferential direction on the outer peripheral surface of the fourth cylindrical portion 244.
In this example, the four first convex portions 251 are formed integrally with the second cylindrical portion 242 in the conductive member covering portion 231, and the four second convex portions 252 are formed in the conductive member covering portion 231. Are formed integrally with the fourth cylindrical portion 244.

In the signal processing unit 200, as shown in FIG. 5, the four first convex portions 251 provided in the second cylindrical portion 242 form the second cylindrical holes 322 in the second housing 32, respectively. Abut against the wall. In addition, as shown in FIG. 6, the plurality of second convex portions 252 provided in the fourth cylindrical portion 244 abuts against the wall forming the fourth cylindrical hole 324 in the second housing 32. As a result, the conductive member covering portion 231 is supported by the second housing 32.
The detailed structure of the conductive member covering portion 231 in the second housing 32 and the signal processing unit 200 and the relationship between the second housing 32 and the conductive member covering portion 231 will be described in detail later.

  The substrate covering portion 232 is basically a cylindrical portion, and a rectangular opening 232a for installing the printed wiring board 210 therein is provided on the side surface thereof. Further, a ring groove 232b for mounting an O-ring 26 for sealing the inside of the housing 30 and the installation portion of the printed wiring board 210 is formed on the rear end side of the substrate covering portion 232.

  The connector portion 233 is a thin portion that protrudes from the end surface 232 c on the rear end side of the substrate covering portion 232 and is formed so as to cover the periphery of the three third connection pins 21 c connected to the printed wiring board 210. The rear end portion of the connector portion 233 is open so that the connector 8a provided at the front end portion of the transmission cable 8 can be received therein. Further, a hole 233a that communicates the inside and the outside is formed on the rear end side of the connector portion 233, and a hook provided on the connector 8a of the transmission cable 8 is hooked into the hole 233a, so that the transmission cable The eight connectors 8a are prevented from dropping from the connector portion 233.

  The covering member 23 configured as described above is formed of an insulating material such as resin. The cover member 23 is integrally formed with the conductive member 22, the first connection pin 21a, the second connection pin 21b, and the three third connection pins 21c. More specifically, in the covering member 23, the heated resin is pushed into a mold in which the conductive member 22, the first connection pin 21a, the second connection pin 21b, and the three third connection pins 21c are set. It is molded by

  In order to unitize the signal processing unit 200, the printed wiring board 210 of the circuit board unit 21 is inserted from the opening 232 a of the formed covering member 23 and is installed at the center of the board covering unit 232. When installing the printed wiring board 210, the tips of the first connection pin 21a, the second connection pin 21b, and the three third connection pins 21c are passed through the through-holes penetrating in the plate thickness direction and soldered. . Then, the 1st connection pin 21a and the conduction member 22 are connected using a conducting wire. Further, the O-ring 26 is attached to the ring groove 232 b of the substrate covering portion 232 of the covering member 23. The O-ring 26 is a well-known O-shaped ring made of fluorine-based rubber.

Next, the holding member 300 will be described.
The holding member 300 is a thin-walled cylindrical member, and as shown in FIG. 4, a protruding portion 300 a that protrudes inward is provided at the rear end portion of the holding member 300. After the holding member 300 is mounted on the second housing 32, the holding member 300 is caulked by pressing a portion corresponding to the concave portion 335 a provided on the fifth outer peripheral surface 335 from the outside. Thereby, the holding member 300 becomes difficult to move with respect to the housing 30, and the signal processing unit 200 is prevented from moving with respect to the housing 30.

Subsequently, the conductive member covering portion 231 in the second housing 32 and the signal processing portion 200 will be described in detail.
FIG. 7A is a view for explaining the structure of the second housing 32 before the signal processing unit 200 is inserted, and FIG. 7B is a diagram before being inserted into the second housing 32. It is a figure for demonstrating the structure of the front-end | tip part in the signal processing part 200 of.
FIG. 8 is a cross-sectional view of the second housing 32 and the signal processing unit 200 shown in FIG. 8A is a VIIIA-VIIIA cross section of FIG. 7, FIG. 8B is a VIIIB-VIIIB cross section of FIG. 7, and FIG. 8C is a VIIIC-VIIIC cross section of FIG. FIG.8 (d) is the VIIID-VIIID cross section of FIG.
Here, FIGS. 8A, 8 </ b> B, 8 </ b> C, and 8 </ b> D respectively show the second housing 32 at a corresponding position when the signal processing unit 200 is inserted into the second housing 32. FIG. 6 is a cross-sectional view of the conductive member covering portion 231.

As shown in FIG. 7A, in the second housing 32, as described above, the first cylindrical hole 321, the second cylindrical hole 322, the third cylindrical hole 323, which have different hole diameters, A fourth cylindrical hole 324 and a fifth cylindrical hole 325 are provided side by side from the front end side to the rear end side.
And in the 2nd housing 32 of this Embodiment, between the 3rd cylindrical hole 323 and the 4th cylindrical hole 324, the inclined surface from which a diameter becomes large gradually toward a rear-end side from the front end side. 324a is formed.

As shown in FIG. 7B, the conductive member covering portion 231 in the signal processing unit 200 includes the cylindrical first cylindrical portion 241, the second cylindrical portion 242, and the second cylindrical portion 242 having different outer diameters as described above. Three cylindrical portions 243 and a fourth cylindrical portion 244 are provided side by side from the front end side to the rear end side. Further, it is a transition portion from the third cylindrical portion 243 to the fourth cylindrical portion 244, and the outer diameter of the distal end portion of the fourth cylindrical portion 244 gradually increases from the distal end side toward the rear end side. An inclined surface 244a is provided.
The first cylindrical portion 242 is provided with four first convex portions 251 that extend along the center line direction and are arranged at intervals of 90 degrees along the circumferential direction. That is, as shown in FIG. 8A, the four first convex portions 251 are provided so as to face the other first convex portions 251 through the second cylindrical portion 242, respectively.
Similarly, the fourth cylindrical portion 244 is provided with four second convex portions 252 that extend along the center line direction and are arranged at intervals of 90 degrees along the circumferential direction. And as shown in FIG.8 (d), the four 2nd convex parts 252 are provided so that the other 2nd convex part 252 may be faced through the 4th cylindrical part 244, respectively.
Moreover, in this Embodiment, the 1st convex part 251 and the 2nd convex part 252 are each provided in the position which mutually overlaps seeing from a center line direction.

Here, as shown in FIG. 7, each of the four first convex portions 251 is located on the distal end side of the first convex portion 251, and the height from the outer peripheral surface of the second cylindrical portion 242 is the distal end. The tapered portion 251a as an example of an inclined portion that gradually increases from the rear end toward the rear end, and the height from the outer peripheral surface of the second cylindrical portion 242 that extends from the tapered portion 251a toward the rear end side is substantially constant. A flat portion 251b is provided.
Similarly, each of the four second convex portions 252 is positioned on the front end side of the second convex portion 252 and the height from the outer peripheral surface of the fourth cylindrical portion 244 gradually increases from the front end toward the rear end. And a flat portion 252b extending from the tapered portion 252a toward the rear end and having a substantially constant height from the outer peripheral surface of the fourth cylindrical portion 244. ing.

Here, as shown in FIG. 8A, in the cross section perpendicular to the center line direction, the diameter of the circumscribed circle in contact with the four first convex portions 251 is defined as a first convex portion diameter Dp1.
Similarly, as shown in FIG. 8D, in the cross section perpendicular to the center line direction, the diameter of the circumscribed circle in contact with the four second convex portions 252 is defined as the second convex portion diameter Dp2.

In the present embodiment, the second outer diameter Do2 in the second cylindrical portion 242 is formed smaller than the second hole diameter Dh2 in the second housing 32 (Do2 <Dh2). The first convex portion diameter Dp1 in the second cylindrical portion 242 is formed to be larger than the second hole diameter Dh2 in the second housing 32 (Dh2 <Dp1).
The fourth outer diameter Do4 in the fourth cylindrical portion 244 is formed to be smaller than the fourth hole diameter Dh4 in the second housing 32 (Do4 <Dh4). Furthermore, the second convex portion diameter Dp2 in the fourth cylindrical portion 244 is formed larger than the fourth hole diameter Dh4 in the second housing 32 (Dh4 <Dp2).
In addition, the third outer diameter Do3 in the third cylindrical portion 243 is formed to be smaller than the third hole diameter Dh3 in the second housing 32 (Do3 <Dh3).

  Further, the second housing 32 of the present embodiment is formed of, for example, SUS430. Further, the conductive member covering portion 231 is made of, for example, PPS (polyphenylenesulfide) resin. Accordingly, the first convex portion 251 formed integrally with the second cylindrical portion 242 of the conductive member covering portion 231 and the second convex portion 252 formed integrally with the fourth cylindrical portion 244 are similarly PPS resin. It is formed with. Here, compared to SUS430, the PPS resin is soft and easily deformed. Therefore, in the present embodiment, the first convex portion 251 and the second convex portion 252 are softer and easier to deform than the second housing 32.

Then, the assembly method of the pressure detection apparatus 5 is demonstrated. The pressure detection device 5 is assembled as shown below.
First, the first housing 31 and the diaphragm head 40 are fitted (press-fitted) until the end surface 31a of the first housing 31 and the abutting surface 41b of the diaphragm head 40 come into contact with each other. Thereafter, a laser beam is irradiated to a portion where the end surface 31a of the first housing 31 and the abutting surface 41b of the diaphragm head 40 are in contact with each other in a direction intersecting the center line direction (for example, a direction orthogonal to the center line direction). Then, the first housing 31 and the diaphragm head 40 are welded.

  Thereafter, the first electrode unit 50 and the piezoelectric element 10 are inserted from the opening on the rear end side in the first housing 31. Thereafter, the coil spring 70 is attached to the tip of the protruding portion 55a of the second electrode portion 55, and the insulating ring 60 is inserted into the protruding portion 55a of the second electrode portion 55. 31 is inserted through the opening on the rear end side. Thereafter, the support member 65 is inserted from the opening on the rear end side in the first housing 31.

  Thereafter, in order to increase the sensitivity and linearity of the piezoelectric element 10, a predetermined load (preload) is applied to the piezoelectric element 10 in the first housing 31. That is, the support member 65 is pressed in the center line direction from the rear end side toward the front end side with a dedicated jig attached to the rear end portion of the support member 65. Then, pressure is applied until the amount of displacement in the center line direction of the end surface on the front end side in the inner portion 42 of the diaphragm head 40 reaches a predetermined length before the support member 65 is pressed. The support member 65 and the first housing 31 are fixed when the end surface on the front end side of the inner side portion 42 of the diaphragm head 40 is displaced by a predetermined length. Examples of the fixing method include irradiation with a laser beam from a direction intersecting the center line direction (for example, a direction orthogonal to the center line direction). The laser beam may be applied to the entire circumference in the circumferential direction, or may be irradiated spotwise at equal intervals in the circumferential direction. After the support member 65 and the first housing 31 are fixed, the dedicated jig is removed. As a result, a preload is applied to the piezoelectric element 10 in the first housing 31.

  Thereafter, the first housing 31 and the second housing 32 are fitted (press-fit) until the vertical surface 315b of the protruding portion 315 of the first housing 31 and the end surface on the front end side of the second housing 32 come into contact with each other. To do. Thereafter, the laser beam is irradiated from a direction intersecting the center line direction (for example, a direction orthogonal to the center line direction) to a portion where the vertical surface 315b of the first housing 31 and the end surface of the second housing 32 are in contact with each other. Then, the first housing 31 and the second housing 32 are welded.

Thereafter, the signal processing unit 200 is inserted from the opening on the rear end side in the second housing 32 toward the front end side.
At this time, first, the conductive member 22 exposed from the conductive member covering portion 231 and the first cylindrical portion 241 of the conductive member covering portion 231 are connected to the fifth cylindrical hole 325 (see FIG. 4) of the second housing 32, the first 4 passes through the fourth cylindrical hole 324 and the third cylindrical hole 323 and enters the second cylindrical hole 322. Further, the second cylindrical portion 242 in the conductive member covering portion 231 passes through the fifth cylindrical hole 325, the fourth cylindrical hole 324, and the third cylindrical hole 323, and the tip of the second cylindrical portion 242 is The rear end of the second cylindrical hole 322 is reached.

Here, in the present embodiment, the first convex portion diameter Dp1 in the second cylindrical portion 242 is formed larger than the second hole diameter Dh2 in the second cylindrical hole 322 of the second housing 32. . As a result, when the signal processing unit 200 is further inserted into the second housing 32, the four first convex portions 251 provided on the distal end side of the second cylindrical portion 242 are respectively on the tapered portion 251a side. The taper portion 251a eventually comes into contact with the wall forming the second cylindrical hole 322.
In the present embodiment, as described above, the second housing 32 is formed of SUS430, and the first convex portion 251 is formed of PPS resin that is softer and easier to deform than SUS430. As a result, when the signal processing unit 200 is further inserted into the second housing 32, each first convex portion 251 is crushed by the wall that forms the second cylindrical hole 322, while being crushed by the second cylindrical hole. Enter into 322. And the flat part 251b in each 1st convex part 251 contact | abuts to the wall which each forms the 2nd cylindrical hole 322, and the 2nd cylindrical part 242 in which the four 1st convex parts 251 were formed in the outer peripheral surface. However, the second cylindrical hole 322 is fitted (press-fit) with an interference fit.

  On the other hand, in the present embodiment, the second outer diameter Do2 of the second cylindrical portion 242 is formed to be smaller than the second hole diameter Dh2 of the second cylindrical hole 322 of the second housing 32. Accordingly, when the second cylindrical portion 242 enters the second cylindrical hole 322, the outer peripheral surface of the second cylindrical portion 242 is unlikely to contact the wall forming the second cylindrical hole 322. .

When the signal processing unit 200 is further inserted into the second housing 32, the third cylindrical portion 243 in the conductive member covering portion 231 is connected to the fifth cylindrical hole 325 and the fourth cylindrical hole 325 of the second housing 32. While passing through the cylindrical hole 324, the tip of the third cylindrical portion 243 reaches the rear end of the third cylindrical hole 323.
Here, in the present embodiment, the third outer diameter Do3 in the third cylindrical portion 243 is formed smaller than the third outer diameter Do3 in the third columnar hole 323. Therefore, the third cylindrical portion 243 is unlikely to contact the wall forming the third cylindrical hole 323, and enters the third cylindrical hole 323 toward the distal end side.

When the signal processing unit 200 is further inserted into the second housing 32, the fourth cylindrical portion 244 in the conductive member covering portion 231 passes through the fifth columnar hole 325 and the fourth cylindrical portion. The leading end of 244 reaches the rear end of the fourth cylindrical hole 324 in the second housing 32.
Here, in the present embodiment, the second convex portion diameter Dp2 in the fourth cylindrical portion 244 is formed larger than the fourth hole diameter Dh4 in the fourth cylindrical hole 324. As a result, when the signal processing unit 200 is further inserted into the second housing 32, the four second convex portions 252 provided in the fourth cylindrical portion 244 are fourth from the tapered portion 252a side. The taper portion 252a eventually comes into contact with the wall forming the fourth cylindrical hole 324.
In the present embodiment, as described above, the second convex portion 252 is softer and easier to deform than the second housing 32. Therefore, when the signal processing unit 200 is further inserted into the second housing 32, each second convex portion 252 is crushed by the wall forming the fourth cylindrical hole 324 and is fourth cylindrical hole 324. Enter inside. And the flat part 252b in each 2nd convex part 252 contact | abuts to the wall which each forms the 4th cylindrical hole 324, and the 4th cylindrical part 244 in which the 4 2nd convex part 252 was formed in the outer peripheral surface. However, it is in a state of being fitted (press-fitted) into the fourth cylindrical hole 324 with an interference fit.

  On the other hand, in the present embodiment, the fourth outer diameter Do4 in the fourth cylindrical portion 244 is formed smaller than the fourth hole diameter Dh4 in the fourth cylindrical hole 324 of the second housing 32. Therefore, when the fourth cylindrical portion 244 enters the fourth cylindrical hole 324, the outer peripheral surface of the fourth cylindrical portion 244 is unlikely to contact the wall forming the fourth cylindrical hole 324. .

  Thereafter, the signal processing unit 200 is further inserted into the second housing 32 until the end surface on the front end side of the substrate covering unit 232 of the signal processing unit 200 abuts against the abutting surface 340 of the second housing 32. Accordingly, the coil spring 70 attached to the protruding portion 55a of the second electrode portion 55 enters the insertion hole 22a of the conductive member 22 of the signal processing unit 200 and is formed on the abutting surface 340 of the second housing 32. The second connection pin 21b connected to the printed circuit board 210 enters the pin recess 340a.

At this time, the second cylindrical portion 242 is directed toward the distal end side of the second cylindrical hole 322 in a state where the flat portion 251b of the first convex portion 251 is in contact with the wall forming the second cylindrical hole 322. Enter.
When the end surface on the front end side of the substrate covering portion 232 is in contact with the abutting surface 340 of the second housing 32, the second cylindrical portion 242 moves in the center line direction (front end side) by the substrate covering portion 232. In addition, the movement of the second cylindrical portion 242 in the circumferential direction and the radial direction is limited by the four first convex portions 251.
Specifically, in the state where the signal processing unit 200 is inserted into the second housing 32 and the second cylindrical portion 242 is inserted into the second columnar hole 322, the four first convex portions 251 are The diameters of circumscribed circles that are crushed toward the second cylindrical portion 242 by the inner walls of the second cylindrical holes 322 and are in contact with the four first convex portions 251 are smaller than the first convex portion diameter Dp1. And it is below 2nd hole diameter Dh2. In this state, the four first convex portions 251 press the inner wall of the second cylindrical hole 322 outward by the elastic force. Accordingly, the movement of the second cylindrical portion 242 in the circumferential direction and the radial direction of the second cylindrical portion 242 is restricted by the four first convex portions 251.

Similarly, the fourth cylindrical portion 244 is directed toward the distal end side of the fourth cylindrical hole 324 in a state where the flat portion 252b of the second convex portion 252 is in contact with the wall forming the fourth cylindrical hole 324. Enter.
Then, in a state where the end surface on the front end side of the substrate covering portion 232 abuts against the abutting surface 340 of the second housing 32, the fourth cylindrical portion 244 is moved in the center line direction (front end side) by the substrate covering portion 232. In addition, the four second convex portions 252 restrict the movement of the second cylindrical portion 242 in the circumferential direction and the radial direction.
More specifically, in a state where the signal processing unit 200 is inserted into the second housing 32, the four second convex portions 252 are each in the fourth cylindrical portion 244 by the inner wall of the fourth cylindrical hole 324. The diameter of the circumscribed circle that is crushed toward the side and is in contact with the four second convex portions 252 is smaller than the second convex portion diameter Dp2 and equal to or smaller than the fourth hole diameter Dh4. In this state, the four second convex portions 252 press the inner wall of the fourth cylindrical hole 324 outward by the elastic force. Thereby, the movement of the fourth cylindrical portion 244 in the circumferential direction and the radial direction is restricted by the four second convex portions 252.

  In the present embodiment, an inclined surface 324 a is formed between the third cylindrical hole 323 and the fourth cylindrical hole 324 in the second housing 32. When the signal processing unit 200 is inserted into the second housing 32, the inclined surface 244 a provided at the tip of the fourth cylindrical portion 244 of the conductive member covering portion 231 and the fourth cylindrical portion 244 The tapered portions 252a of the four formed second convex portions 252 abut against the inclined surface 324a. Thereby, compared with the case where this configuration is not provided, the fourth cylindrical portion 244 is suppressed from entering the third columnar hole 323 toward the distal end side, and the signal processing portion for the second housing 32 is suppressed. The positional accuracy in the direction of the center line 200 can be increased.

Here, since the conductive member covering portion 231 of the present embodiment has the above-described configuration, when the signal processing portion 200 is inserted into the second housing 32, the first protrusion provided in the second cylindrical portion 242 is provided. The second convex portion 252 provided in the portion 251 and the fourth cylindrical portion 244 contacts the wall forming the hole 320 of the second housing 32. On the other hand, the outer peripheral surfaces of the first cylindrical portion 241, the second cylindrical portion 242, the third cylindrical portion 243 and the fourth cylindrical portion 244 in the conductive member covering portion 231 form a hole 320 of the second housing 32. It is difficult to touch the wall. That is, in the second cylindrical portion 242 and the fourth cylindrical portion 244, a part of the outer peripheral surface in the circumferential direction is in contact with the hole 320 of the second housing 32, while the signal processing unit 200 is in the second housing 32. Will be inserted.
Therefore, in this Embodiment, compared with the case where the outer peripheral surface of the conductive member coating | cover part 231 is contacting with the inner wall of the hole 320 of the 2nd housing 32 in the whole circumferential direction, the conductive member coating | coated part 231 and 2nd. The contact area with the wall forming the hole 320 in the housing 32 is reduced. Thereby, the frictional force generated between the conductive member covering portion 231 and the second housing 32 when the signal processing unit 200 is inserted into the second housing 32 is reduced. Therefore, the force required to insert the signal processing unit 200 into the second housing 32 is reduced, and the signal processing unit 200 is inserted into the second housing 32 as compared with the case where this configuration is not provided. It becomes easy to do.

For example, the signal processing unit 200 is inserted into the second housing 32 and supported while the outer peripheral surface of the conductive member covering portion 231 is in contact with the wall forming the hole 320 of the second housing 32 in the entire circumferential direction. The shape and dimensions of the hole 320 and the conductive member covering portion 231 in the second housing 32 are required to be highly accurate over the entire circumferential direction.
For example, when the accuracy of the hole 320 and / or the conductive member covering portion 231 in the second housing 32 is low, the conductive member covering portion 231 cannot be inserted into the hole 320 in the second housing 32 because it is too tight or loose. There is a possibility that the conductive member covering portion 231 cannot be supported by the second housing 32.

On the other hand, in the present embodiment, the outer peripheral surfaces of the first convex portion 251 and the second convex portion 252 easily come into contact with the wall that forms the hole 320 of the second housing 32, whereas the conductive member covering portion 231 has the first outer surface. The outer peripheral surfaces of the first cylindrical portion 241, the second cylindrical portion 242, the third cylindrical portion 243, and the fourth cylindrical portion 244 are unlikely to come into contact with the wall forming the hole 320. Further, the conductive member covering portion 231 is inserted into the second housing 32 by the first convex portion 251 and the second convex portion 252 coming into contact with the wall forming the hole 320 and being deformed.
Therefore, even if the accuracy of the shape and dimensions of the hole 320 and the conductive member covering portion 231 in the second housing 32 is low compared to the case without this configuration, It becomes easy to insert the conductive member covering portion 231, and the conductive member covering portion 231 can be supported by the second housing 32.

In the present embodiment, each of the four first convex portions 251 has a tapered portion 251a on the tip side. When the signal processing unit 200 is inserted into the second housing 32, the rear end portion of the wall forming the second cylindrical hole 322 extends from the front end side to the rear end side along the outer peripheral surface of the tapered portion 251a. Toward the first convex portion 251. Then, the tapered portion 251a is gradually crushed by the rear end portion of the wall forming the second cylindrical hole 322 from the front end side toward the rear end side, and into the second cylindrical hole 322 toward the front end side. Guided. Thereby, even if it is a case where the 1st convex part diameter Dp1 is larger than 2nd hole diameter Dh2 in the 2nd cylindrical hole 322, compared with the case where the 1st convex part 251 does not have taper part 251a. The second cylindrical portion 242 can be more easily inserted into the second cylindrical hole 322 of the second housing 32.
Similarly, each of the four second convex portions 252 has a tapered portion 252a on the tip side. Thereby, even if it is a case where the 2nd convex part diameter Dp2 is larger than the 4th hole diameter Dh4 in the 4th cylindrical hole 324, compared with the case where the 2nd convex part 252 does not have the taper part 252a. The fourth cylindrical portion 244 can be more easily inserted into the fourth cylindrical hole 324 of the second housing 32.

After the signal processing unit 200 is inserted into the second housing 32, the holding member 300 is moved from the rear end side until the protruding portion 300a of the holding member 300 hits the end surface 232c of the substrate covering portion 232 of the signal processing unit 200. It fits into the signal processing unit 200. Then, in a state where the end surface 232c of the signal processing unit 200 and the protruding portion 300a of the holding member 300 are in contact with each other, a portion corresponding to the concave portion 335a of the fifth outer peripheral surface 335 of the second housing 32 is added to the holding member 300. The holding member 300 is caulked to the second housing 32 by being pressed. Accordingly, the holding member 300 is difficult to move with respect to the housing 30, and the signal processing unit 200 is difficult to move with respect to the housing 30.
In this way, the pressure detection device 5 is assembled.

Here, the electrical connection structure in the pressure detection apparatus 5 mentioned above is demonstrated.
First, the end face on the front end side of the piezoelectric element 10 is electrically connected to the metal housing 30 via the metal first electrode portion 50 and the diaphragm head 40.

  On the other hand, the end surface on the rear end side of the piezoelectric element 10 is electrically connected to the metal second electrode portion 55, and the second electrode portion 55 is made of a metal coil spring via the protruding portion 55 a. 70 is electrically connected. The coil spring 70 is electrically connected to the metallic conductive member 22, and the conductive member 22 is electrically connected to the printed wiring board 210. On the other hand, the outer diameter of the protruding portion 55 a of the second electrode portion 55 is smaller than the hole diameter of the first hole 651 of the support member 65, and the outer diameter of the tip portion of the conductive member 22 is the second hole 652 of the support member 65. Is smaller than the pore diameter. That is, the second electrode portion 55, the coil spring 70, and the conductive member 22 are not electrically connected to the support member 65. Therefore, the charge signal transmission path from the second electrode portion 55 to the printed wiring board 210 via the coil spring 70 and the conductive member 22 is an insulating ring 60 and a covering member 23 each made of an insulator. Is electrically insulated from the metal housing 30.

When the pressure detecting device 5 configured as described above is attached to the cylinder head 4, the diaphragm head 40 of the sensor unit 100 is inserted into the communication hole 4a formed in the cylinder head 4 first, The male screw 332 a formed in the second housing 32 of the housing 30 is screwed into the female screw 4 e formed in the communication hole 4 a of the cylinder head 4.
By mounting the pressure detection device 5 on the cylinder head 4, the housing 30 is electrically connected to the metal cylinder head 4. Since the cylinder head 4 is in a state of being electrically grounded, in the pressure detection device 5, the tip portion of the piezoelectric element 10 is grounded via the housing 30. Here, in this example, the side surface of the piezoelectric element 10 and the inner wall surface of the housing 30 are in contact with each other, but the resistance value is extremely large because the piezoelectric element 10 is made of an insulator. The electric charge generated with the pressure change is generated at both ends of the piezoelectric element 10 in the center line direction.

Next, the seal member 7 will be described with reference to FIGS. 1 and 2.
The seal member 7 includes an end surface in the tightening direction of the sensor unit 100 on the surrounding wall forming the communication hole 4 a in the cylinder head 4, the third outer peripheral surface 333 and the fourth outer peripheral surface 334 of the housing 30 of the pressure detection device 5. The first seal member 71 is disposed between the connection surface and the connection surface. The seal member 7 is a second seal member 72 disposed between the inclined portion 4 c of the communication hole 4 a of the cylinder head 4 and the inclined surface 315 a of the first housing 31 of the housing 30 of the pressure detection device 5. have. As the first seal member 71, a metal metal gasket can be used, and as the second seal member 72, a fluorine rubber (FKM) O-ring can be used.

Next, the pressure detection operation by the pressure detection device 5 of the present embodiment will be described.
During operation of the internal combustion engine 1, the combustion pressure generated in the combustion chamber C is applied to the inner portion 42 of the diaphragm head 40 of the sensor unit 100. The combustion pressure applied to the diaphragm head 40 acts on the piezoelectric element 10 sandwiched between the first electrode portion 50 and the second electrode portion 55, so that the piezoelectric element 10 corresponds to the combustion pressure. Charge is generated. The electric charge generated in the piezoelectric element 10 is applied to the circuit board portion 21 through the second electrode portion 55, the coil spring 70 and the conductive member 22. The charge applied to the circuit board unit 21 is amplified in the circuit board unit 21, and then the voltage corresponding to the charge is supplied to the third connection pin 21 c connected to the circuit board unit 21 and the transmission cable 8. Is supplied to the control device 6.

  Here, as shown in FIG. 1, the pressure detection device 5 of the present embodiment is used by being mounted on the cylinder head 4 of the internal combustion engine 1, for example. In such an internal combustion engine 1, vibration may occur due to the operation of the piston 3 or the like provided in the combustion chamber C. Further, in such an internal combustion engine 1, when abnormal combustion such as knocking occurs in the combustion chamber C, there is a possibility that a large vibration may occur as compared with normal combustion. When the vibration generated in the combustion chamber C is transmitted to the pressure detection device 5 and the conduction member 22 of the pressure detection device 5 vibrates, the conduction member 22 is disconnected, the conduction member 22 and the coil spring 70 or the print. There is a risk that problems such as poor contact at the connection with the wiring board 210 may occur.

  In the present embodiment, the conductive member covering portion 231 includes four first convex portions 251 provided on the second cylindrical portion 242 and four second convex portions 252 provided on the fourth cylindrical portion 244. Each presses the second housing 32 from the inside, so that the second housing 32 is fitted (press-fitted) with an interference fit and supported. Therefore, even when vibration occurs in the combustion chamber C, the movement of the conductive member covering portion 231 in the second housing 32 is suppressed as compared with the case where this configuration is not provided, and vibration is generated. Is suppressed. Thereby, it is suppressed that the conductive member 22 vibrates with the vibration of the conductive member covering portion 231, and the disconnection of the conductive member 22 due to the vibration of the conductive member 22 or the poor contact at the connection portion of the conductive member 22. Can be suppressed.

  In the present embodiment, the four first convex portions 251 are provided on the second cylindrical portion 242 located on the front end side of the conductive member covering portion 231, and the fourth cylindrical portion 244 located on the rear end side. Four second convex portions 252 are provided. The four first convex portions 251 and the four second convex portions 252 are in contact with the second housing 32, thereby supporting the conductive member covering portion 231. That is, in the present embodiment, the conductive member covering portion 231 is supported at both the front end side and the rear end side of the conductive member covering portion 231. Thereby, for example, the conductive member 22 covered with the conductive member covering portion 231 and the conductive member covering portion 231 is compared with the case where the conductive member covering portion 231 is supported only at one end on the front end side or the rear end side. The vibration in the housing 32 can be further suppressed. And compared with the case where this structure is not provided, it is possible to further suppress the occurrence of disconnection of the conductive member 22 or poor contact at the connecting portion of the conductive member 22 due to the vibration of the conductive member 22. become.

Next, another embodiment of the present invention will be described.
FIG. 9 and FIG. 10 are diagrams showing an example of the structure of the tip portion of the signal processing unit 200 according to another embodiment.

In the present embodiment, four first convex portions 251 are provided on the outer peripheral surface of the second cylindrical portion 242 located on the front end side of the conductive member covering portion 231, and positioned on the rear end side of the conductive member covering portion 231. Four second convex portions 252 are provided on the outer peripheral surface of the fourth cylindrical portion 244. However, the number of the first protrusions 251 and the second protrusions 252 is not limited to four.
For example, as shown in FIG. 9A, three first convex portions 251 and three second convex portions 252 may be provided. Moreover, the number of the 1st convex part 251 and the 2nd convex part 252 is not restricted to this, As long as it is plural, it may be 2 each and may be 5 or more.

In the present embodiment, the four first convex portions 251 and the four second convex portions 252 are provided at positions that overlap each other when viewed along the center line direction. However, the first convex portion 251 and the second convex portion 252 do not necessarily overlap when viewed along the center line direction.
For example, as shown in FIG. 9B, four first convex portions 251 are provided on the outer peripheral surface of the second cylindrical portion 242 so as to be arranged at intervals of 90 degrees in the circumferential direction, and the four second convex portions 252 are provided. May be arranged on the outer peripheral surface of the fourth cylindrical portion 244 at intervals of 90 degrees in the circumferential direction, and may be shifted by 45 degrees in the circumferential direction from the first convex portion 251 when viewed from the center line direction. In addition, the angle which shifts the 1st convex part 251 and the 2nd convex part 252 seeing from a centerline direction is not restricted to 45 degree | times.

Further, in the present embodiment, four first convex portions 251 are provided on the second cylindrical portion 242 and four second convex portions 252 are provided on the fourth cylindrical portion 244 in the same number as the first convex portions 251. It was. However, the number of the first protrusions 251 and the number of the second protrusions 252 are not necessarily the same.
For example, as shown in FIG. 9C, three first convex portions 251 may be provided on the second cylindrical portion 242 and four second convex portions 252 may be provided on the fourth cylindrical portion 244. In this case, as shown in FIG. 9C, the first convex portion 251 and the second convex portion 252 may be provided so as to partially overlap each other when viewed from the center line direction. You may provide so that it may not overlap with the 2nd convex part 252 seeing from a center line direction. In addition, the number which provides the 1st convex part 251 and the 2nd convex part 252 is not restricted to this.

In the present embodiment, the first convex portion 251 is provided at the distal end of the second cylindrical portion 242 located on the distal end side of the conductive member covering portion 231, and the fourth is located on the rear end side of the conductive member covering portion 231. The second convex portion 252 is provided in the cylindrical portion 244 of the above. However, the positions where the convex portions 250 (see FIG. 3) are provided are not limited to the two locations of the second cylindrical portion 242 and the fourth cylindrical portion 244. A plurality of convex portions 250 may be provided in a portion other than the second cylindrical portion 242 and the fourth cylindrical portion 244, and the plurality of convex portions 250 may be provided along the center line direction in the conductive member covering portion 231. It may be provided at more than one place.
For example, as shown in FIG. 9D, the first cylindrical portion 242 is provided with a first convex portion 251, the fourth cylindrical portion 244 is provided with a second convex portion 252, and the second cylindrical portion Still another convex portion 253 can be provided at the rear end of 242.
However, in the case where three or more convex portions 250 are provided along the center line direction of the conductive member covering portion 231, if the number of the convex portions 250 is too large, the periphery where the convex portions 250 and the holes 320 of the second housing 32 are formed. There is a possibility that the friction with the wall increases and it becomes difficult to insert the signal processing unit 200 into the second housing 32. Therefore, it is more preferable to provide the convex portions 250 at two locations on the front end side and the rear end side of the conductive member covering portion 231.

Further, in the present embodiment, four first convex portions 251 are provided at intervals of 90 degrees in the circumferential direction of the outer peripheral surface of the second cylindrical portion 242, and the four second convex portions 252 are provided in the fourth cylinder. The portions 244 are provided at intervals of 90 degrees in the circumferential direction of the outer peripheral surface.
However, the four first convex portions 251 and the four second convex portions 252 are not necessarily provided at an interval of 90 degrees. For example, as shown to Fig.10 (a), the space | interval of adjacent 1st convex part 251 and adjacent 2nd convex part 252 may be smaller than 90 degree | times, and may be larger than 90 degree | times. .
However, in order to support the conductive member 22 accommodated in the conductive member covering portion 231 along the center line in the hole 320 of the second housing 32, the plurality of first convex portions 251 include the second cylindrical portion. It is preferable that they are provided symmetrically with respect to the center line of 242 as the symmetry axis. For example, when there are four first convex portions 251, it is preferable to provide them at 90 degree intervals. Similarly, the plurality of second convex portions 252 are preferably provided symmetrically with respect to the center line of the fourth cylindrical portion 244, and when there are four second convex portions 252, at intervals of 90 degrees. It is preferable to provide it.

Moreover, in this Embodiment, the 1st convex part 251 and the 2nd convex part 252 were each provided along the centerline direction. However, as shown in FIG. 10B, the first convex portion 251 and the second convex portion 252 may be provided inclined with respect to the center line direction.
In this case, when the signal processing unit 200 is inserted into the second housing 32, the signal processing unit 200 is placed in a direction in which the first convex portion 251 and the second convex portion 252 are inclined with respect to the center line direction. It is preferable to insert while rotating. Thereby, the frictional force which arises between the surrounding wall which forms the hole 320 of the 2nd housing 32, and the 1st convex part 251 and the 2nd convex part 252 at the time of insertion can be reduced.

Furthermore, in the present embodiment, the four first convex portions 251 are arranged at intervals in the circumferential direction of the second cylindrical portion 242 at the same position in the center line direction of the second cylindrical portion 242. Provided. Similarly, the four second convex portions 252 are provided at the same position in the center line direction of the fourth cylindrical portion 244 so as to be arranged at intervals in the circumferential direction of the fourth cylindrical portion 244.
However, for example, as shown in FIG. 10C, the plurality of convex portions 250 are provided so as to be shifted in the center line direction of the conductive member covering portion 231, so that the plurality of convex portions 250 are arranged around the conductive member covering portion 231. The direction may not overlap each other. However, in this case, it is preferable to provide the plurality of convex portions 250 so that the directions in which the plurality of convex portions 250 protrude are different when viewed from the center line direction.

Furthermore, in the present embodiment, the first convex portion 251 is provided in the second cylindrical portion 242 and the second convex portion 252 is provided in the fourth cylindrical portion 244, whereby the convex portion 250 is replaced with the conductive member covering portion 231. In FIG. 2, the front end side and the rear end side are divided.
However, for example, as shown in FIG. 10 (d), a plurality of convex portions 250 may be provided integrally from the front end side to the rear end side of the conductive member covering portion 231.

  In the present embodiment, the first cylindrical portion 241, the second cylindrical portion 242, the third cylindrical portion 243, and the fourth cylindrical portion 244 are arranged side by side on the conductive member covering portion 231, so that the distal end side is provided. The outer diameter was gradually changed from the rear end side to the rear end side. However, for example, the conductive member covering portion 231 may be configured such that the outer diameter continuously changes from the front end side to the rear end side. In this case, the entire conductive member covering portion 231 may be configured such that the outer diameter changes continuously, or as shown in FIG. A part of may be configured such that the outer diameter continuously changes.

In the present embodiment, the first convex portion 251 has the tapered portion 251a and the flat portion 251b. However, the first convex portion 251 does not necessarily have the tapered portion 251a. As the shape of the first convex portion 251, any shape can be adopted as long as the second cylindrical portion 242 can be supported by coming into contact with the wall forming the second cylindrical hole 322 of the second housing 32. it can.
Similarly, the second convex portion 252 does not necessarily have the tapered portion 252a. The shape of the second convex portion 252 is that the fourth cylindrical portion 244 is brought into contact with the wall forming the fourth cylindrical hole 324. Any shape can be adopted as long as it can be supported.

  In addition, the form of the conductive member covering portion 231 shown in FIGS. 9 and 10 is an example, and the present invention is not limited to these forms. For example, you may combine each form shown to Fig.9 (a)-(d) and Fig.10 (a)-(d) arbitrarily.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Cylinder block, 3 ... Piston, 4 ... Cylinder head, 5 ... Pressure detection apparatus, 6 ... Control apparatus, 7 ... Sealing member, 8 ... Transmission cable, 10 ... Piezoelectric element, 21 ... Circuit board part , 22 ... conductive member, 23 ... cover member, 231 ... conductive member covering portion, 251 ... first convex portion, 252 ... second convex portion, 26 ... O-ring, 30 ... housing, 40 ... diaphragm head, 50 ... first. Electrode part, 55 ... second electrode part, 60 ... insulating ring, 65 ... support member, 70 ... coil spring, 71 ... first seal member, 72 ... second seal member, 100 ... sensor part, 200 ... Signal processing unit, 300 ... holding member

Claims (5)

A cylindrical housing in which a hole extending in the axial direction from the front end toward the rear end is formed;
A diaphragm provided on the front end side of the housing;
A piezoelectric element that is arranged on the rear end side of the diaphragm and that performs output according to the pressure acting through the diaphragm;
A conductive member that conducts the output from the piezoelectric element toward the rear end;
A conductive member containing portion that is provided along the axial direction and accommodates the conductive member therein and is fitted and attached to the hole of the housing;
The conductive member accommodating portion is
Projecting from the outer peripheral surface of the conductive member accommodating portion and arranged at intervals in the circumferential direction of the conductive member accommodating portion , each being provided along the axial direction of the conductive member accommodating portion, and inside the hole in the housing a first projection group including a plurality of first convex portions for supporting the contact along the axial direction the conductive member accommodating portion for the peripheral surface,
The first convex portion group is disposed away from the rear end side, protrudes from the outer peripheral surface of the conductive member housing portion, and is arranged at intervals in the circumferential direction of the conductive member housing portion , each of which is the conductive member housing portion. provided along the axial direction, in contact along the axial direction against the inner peripheral surface of said hole in said housing, a plurality of the first convex portion of the plurality of supporting the conductive member receiving portion first A pressure detection device comprising: a second convex portion group including two convex portions. The plurality of first convex portions in the first convex portion group are arranged at intervals in the circumferential direction of the conductive member accommodating portion at the same position in the axial direction of the conductive member accommodating portion,
The plurality of second convex portions in the second convex portion group are arranged at intervals in the circumferential direction of the conductive member accommodating portion at the same other position in the axial direction of the conductive member accommodating portion. The pressure detection device according to claim 1, wherein: The conductive member accommodating portion has a cylindrical shape,
The first convex portion group includes four first convex portions arranged at intervals of 90 degrees in the circumferential direction of the conductive member accommodating portion,
The second convex portion group includes four second convex portions arranged at intervals of 90 degrees in the circumferential direction of the conductive member accommodating portion,
3. The pressure detection device according to claim 1, wherein each of the first protrusions and each of the second protrusions are provided so as to overlap each other when viewed from the axial direction. The plurality of first convex portions are located at the tip portion of the first convex portion, and an inclined portion in which the height from the outer peripheral surface of the conductive member housing portion gradually increases from the front end side toward the rear end side. A flat portion extending from the rear end portion of the inclined portion along the axial direction and having a substantially constant height from the outer peripheral surface of the conductive member housing portion to the rear end side from the front end side ,
The plurality of second convex portions are located at the tip portion of the second convex portion, and the inclined portion is such that the height from the outer peripheral surface of the conductive member housing portion gradually increases from the front end side toward the rear end side. A flat portion extending from the rear end portion of the inclined portion along the axial direction and having a substantially constant height from the outer peripheral surface of the conductive member housing portion to the rear end side. The pressure detection device according to any one of claims 1 to 3, wherein A cylindrical housing in which a hole extending in the axial direction from the front end toward the rear end is formed;
A diaphragm provided on the front end side of the housing;
A piezoelectric element that is arranged on the rear end side of the diaphragm and that performs output according to the pressure acting through the diaphragm;
A conductive member that conducts the output from the piezoelectric element toward the rear end;
Accommodating the conductive member therein, and a circumferentially spaced parallel beauty, conductive member receiving portion, each having a plurality of convex portions extending along the axial direction as to protrude from the outer circumferential surface,
The conductive member accommodating portion is inserted into the hole in the housing , and the plurality of convex portions of the conductive member accommodating portion are deformed by contacting the inner peripheral surface of the hole, and are elastically applied. A pressure detecting device that presses the inner peripheral surface .

Images