JP2015219131A - Pressure detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure detection device capable of preventing the breakdown of a piezoelectric element due to the lifting of the piezoelectric element when it is subjected to combustion pressure.SOLUTION: A case 33 is equipped with a preload receiving part 33f provided so as to protrude from the outer wall surface 33e of a cylinder part 33b. The preload receiving part 33f plays the role of stopping the load applied to a preload application member 37 when a piezoelectric element 31, electrode parts 34, 35, and an insulation ring 36 are pushed into a lid part 33c side via the preload application member 37. It is thereby possible to shorten the extension range of the cylinder part 33b of the case 33 when the load applied to the preload application member 37 is released. This makes it hard for the preload acting on the electrodes 34, 35 and the piezoelectric element 31 to be released. Therefore, it is possible to prevent the breakdown of the piezoelectric element 31 due to its lifting from the electrodes 34, 35.

Description

  The present invention relates to a pressure detection device that detects a combustion pressure in a combustion chamber.

  Conventionally, for example, Patent Document 1 proposes a pressure detection device that detects a combustion pressure in a combustion chamber. Specifically, a bottomed cylindrical pressurization that accommodates the first electrode portion, the second electrode portion, the piezoelectric element sandwiched between the electrode portions, the first electrode portion, the piezoelectric element, and the second electrode portion in this order. There has been proposed a pressure detection device including a support member that is housed in a member and a pressure member and is fixed to the opening side of the pressure member.

  In such a configuration, the support member is pressurized while a load is applied to the bottom side of the pressure member with respect to the support member in a state where each electrode portion, the piezoelectric element, and the support member are accommodated in the pressure member. It is fixed to the member. Thereby, the load applied to the support member by the bottom of the pressure member is received. Therefore, a preload is applied in advance to the piezoelectric elements sandwiched between the electrode portions.

  Furthermore, the pressure detection device includes a diaphragm to which combustion pressure is applied. The diaphragm is brought into contact with the bottom portion of the pressure member, or is brought into contact with the first electrode portion through a through hole provided in the bottom portion. As a result, the combustion pressure is transmitted to the piezoelectric element.

International Publication No. 2013/147260

  However, in the above conventional technique, the load of the support member is received by the bottom portion of the pressure member. Therefore, when the load is no longer applied to the support member after the support member is fixed to the pressure member, each electrode portion and the piezoelectric element A part of the preload applied to is released. A part of the released preload becomes a repulsive force and extends a portion from the bottom of the pressure member to the fixing position of the support member in the cylindrical portion of the pressure member.

  Thereby, when the piezoelectric element floats or tilts from each electrode portion due to the combustion pressure applied to the piezoelectric element, local stress is applied to the piezoelectric element. Since the piezoelectric element is a brittle material and has a property of being weak against local stress, there is a problem that the piezoelectric element is destroyed by the local stress.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a pressure detection device capable of preventing the piezoelectric element from being broken due to the floating of the piezoelectric element when the piezoelectric element is subjected to combustion pressure.

  In order to achieve the above object, the invention described in claim 1 is a pressure detection device that is attached to a combustion mechanism constituting the combustion chamber and detects the combustion pressure in the combustion chamber, and is characterized by the following points. .

  First, a bottomed cylindrical shape in which one opening portion of the hollow cylindrical tube portion (33b) is closed by the lid portion (33c) and the other opening portion (33d) of the cylindrical portion (33b) is opened. The case (33) is provided.

  Also, the piezoelectric element (31) that detects the pressure based on the combustion pressure while being accommodated in the cylindrical part (33b), and the electrode part (34) that is accommodated in the cylindrical part (33b) and sandwiches the piezoelectric element (31). , 35).

  Further, the piezoelectric element (31) and the electrode part (34, 35) are fixed to the other opening (33d) in a state where the piezoelectric element (31) and the electrode part (34, 35) are pushed into the lid part (33c). 34, 35) and a preload applying material (37) for applying a preload to the electrode portions (34, 35) and the piezoelectric element (31).

  The case (33) is provided so as to protrude from the outer wall surface (33e) of the cylindrical portion (33b), and the piezoelectric element (31) and the electrode portion (34, 34) via the preload application material (37). 35) is provided with a preload receiving portion (33f) for receiving a load applied to the preload applying material (37) when being pushed into the lid portion (33c).

  According to this, the load applied to the preload application material (37) is received by the preload receiving portion (33f). For this reason, when the load of the preload application material (37) is released, a part of the preload applied to each electrode part (34, 35) and the piezoelectric element (31) becomes a repulsive force and the case (33). It depends on the length from the preload receiving portion (33f) to the fixing position of the preload application material (37) with respect to the tube portion (33b) in the tube portion (33b). That is, the length that the repulsive force is applied to the cylindrical portion (33b) of the case (33) is configured so that the load applied to the preload applying material (37) is received by the lid portion (33c) of the case (33). Can also be shortened. In other words, the preload applied to the electrode portions (34, 35) and the piezoelectric element (31) can be made difficult to be released.

  This prevents local stress from being applied to the piezoelectric element (31) due to the piezoelectric element (31) floating or tilting from the electrode portions (34, 35) by the combustion pressure applied to the piezoelectric element (31). be able to. Therefore, when the piezoelectric element (31) receives the combustion pressure, it is possible to prevent the piezoelectric element (31) from being broken due to the lift of the piezoelectric element (31) from the electrode portions (34, 35).

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

1 is a partial cross-sectional view of a pressure detection device according to a first embodiment of the present invention. It is a top view when a case is seen from the cover part side to the cylinder part side. It is the figure which showed the aging process among the manufacturing processes of a pressure detection apparatus. It is the figure which showed the extension range of the cylinder part when releasing the load to a preload application material. It is the figure which showed the aging process with respect to the structure by which the preload receiving part is not provided. It is a figure for demonstrating the extension range of the cylinder part of a case in the structure in which the preload receiving part is not provided. It is a figure for demonstrating the fulcrum of a case in the structure in which the preload receiving part is not provided. It is a figure for demonstrating the fulcrum of a case in the structure provided with the preload receiving part. It is the top view which showed the preload receiving part which concerns on 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The pressure detection device according to the present embodiment is a device that is attached to a combustion mechanism that constitutes a combustion chamber and detects the combustion pressure in the combustion chamber. The combustion mechanism is an engine mounted on a vehicle, for example. As shown in FIG. 1, the pressure detection device 1 includes a housing 10, a diaphragm 20, and a preload holding unit 30.

  The housing 10 is a rod-like component that makes the appearance of the pressure detection device 1. The housing 10 is made of, for example, a metal material. One end 11 of the housing 10 on the combustion chamber side is cylindrical. Further, the housing 10 has a screw portion 12 formed on the side wall, and is screwed to the engine block via the screw portion 12. Note that components such as a circuit board and a connector (not shown) are provided on the opposite side of the housing 10 from the one end 11.

  The diaphragm 20 is a bottomed cylindrical part that transmits a load based on the combustion pressure in the combustion chamber to the preload holding unit 30. Specifically, the diaphragm 20 includes a hollow cylindrical support portion 21 and a pressure receiving portion 22 that closes one opening of the support portion 21. The support portion 21 has a hollow portion 23, and the preload holding portion 30 is accommodated in the hollow portion 23. The pressure receiving part 22 is a part to which combustion pressure is applied.

  Moreover, the support part 21 has the protrusion part 25 in which a part of the outer wall surface 24 protrudes from the outer wall surface 24. The protruding portion 25 is a portion welded to the open end of the one end portion 11 of the housing 10. Thereby, the diaphragm 20 is fixed to the housing 10 by the welded portion 40.

  The preload holding unit 30 is a component separated from the diaphragm 20 and is configured to detect the magnitude of the load transmitted from the diaphragm 20. Such a preload holding unit 30 includes a piezoelectric element 31 and a preload application unit 32.

  The piezoelectric element 31 is a plate-like load detection element for detecting an applied load. Specifically, the piezoelectric element 31 generates a charge corresponding to the magnitude of the load when a load is applied, and is made of, for example, a piezoelectric body. Therefore, the piezoelectric element 31 converts the magnitude of the applied load into, for example, a voltage and outputs the voltage.

  The piezoelectric element 31 may be configured to generate charges in the central axis direction of the housing 10. On the other hand, the piezoelectric element 31 may be configured to generate charges in a direction perpendicular to the central axis direction of the housing 10.

  The preload application unit 32 has a structure in which the piezoelectric element 31 is sandwiched and pressed against the piezoelectric element 31 by applying a predetermined preload to the piezoelectric element 31. Specifically, the preload application unit 32 includes a case 33, a first electrode unit 34, a second electrode unit 35, an insulating ring 36, and a preload application material 37.

  The case 33 is a bottomed cylindrical part having a hollow portion 33a. The case 33 includes a hollow cylindrical tube portion 33b and a lid portion 33c that closes one opening of the tube portion 33b. Therefore, the case 33 has a structure in which the other opening 33d of the cylindrical portion 33b is opened.

  The case 33 includes a preload receiving portion 33f provided on the outer wall surface 33e of the cylindrical portion 33b. The preload receiving portion 33f is a portion from which a part of the outer wall surface 33e of the cylindrical portion 33b protrudes. The preload receiving portion 33f is a load applied to the preload applying material 37 when the piezoelectric element 31, each electrode portion 34, 35, and the insulating ring 36 are pushed toward the lid portion 33c via the preload applying material 37. It plays the role of catching up. The case 33 is a fulcrum of vibration of the case 33 in a state where the case 33 is accommodated in the diaphragm 20.

  In the present embodiment, as shown in FIG. 2, the preload receiving portion 33f is continuously provided on the outer wall surface 33e of the cylindrical portion 33b so as to go around the outer wall surface 33e. FIG. 2 is a plan view of the case 33 as viewed from the lid portion 33c side to the cylindrical portion 33b side. Further, as shown in FIG. 1, the cross section of the preload receiving portion 33f is triangular.

  Further, the preload receiving portion 33f is provided at a position away from the opening end 33g of the cylindrical portion 33b of the case 33 in the outer wall surface 33e. In other words, the cylindrical portion 33b of the case 33 is provided with a region where the preload receiving portion 33f is not formed on the opening end 33g side of the other opening portion 33d with respect to the preload receiving portion 33f of the outer wall surface 33e. Yes. This space is a welding area 33h for welding the preload applying material 37 to the cylindrical portion 33b. That is, the cylinder part 33b has the welding area 33h in the outer wall surface 33e.

  The first electrode portion 34 is a plate-like component accommodated in the hollow portion 33 a so as to be in contact with the bottom surface 33 i of the hollow portion 33 a of the case 33. The first electrode portion 34 abuts on the piezoelectric element 31 and functions as one electrode of the piezoelectric element 31.

  The second electrode portion 35 is a component housed in the hollow portion 33 a of the case 33 so as to be separated from the inner wall surface 33 j of the case 33. The second electrode portion 35 functions as the other electrode of the piezoelectric element 31. The second electrode portion 35 is in contact with the opposite side of the piezoelectric element 31 to the second electrode portion 35 in the hollow portion 33 a of the case 33. Thereby, the second electrode part 35 sandwiches the piezoelectric element 31 together with the first electrode part 34.

  The insulating ring 36 is a ring-shaped component that is disposed in the hollow portion 33 a of the case 33 and that insulates the second electrode portion 35 and the preload application material 37. The insulating ring 36 is in contact with the opposite side of the second electrode portion 35 to the piezoelectric element 31 side. The insulating ring 36 is made of ceramics such as alumina. A signal line (not shown) for taking out a signal from the second electrode portion 35 is disposed in the hollow portion of the insulating ring 36.

  The preload applying material 37 is a component that contacts the opposite side of the insulating ring 36 from the second electrode portion 35. The preload application material 37 has a convex cross section in a direction parallel to the central axis of the case 33. In the preload application material 37, a convex portion having a narrow width in the direction perpendicular to the central axis of the case 33 is inserted into the other opening 33 d of the case 33. The preload applying material 37 has a through hole 37 a provided along the central axis of the case 33. This through hole 37 a is used as a space for taking out a signal from the second electrode portion 35.

  Further, the preload applying material 37 is fixed to the other opening 33d of the case 33 by welding in a state where the piezoelectric element 31, the electrode portions 34 and 35, and the insulating ring 36 are pushed into the lid portion 33c side of the case 33. Has been. That is, the preload application material 37 is welded to the welding area 33 h of the cylindrical portion 33 b of the case 33. Thereby, the preload application material 37 is fixed to the case 33 by the welded portion 41. Further, the preload application material 37 applies a preload to the piezoelectric element 31, the electrode parts 34 and 35, and the insulating ring 36 and presses the electrode parts 34 and 35 and the piezoelectric element 31.

  Thus, one of the purposes of applying a predetermined preload to the piezoelectric element 31 is that the combustion chamber generates not only positive pressure but also negative pressure, so that even if a negative pressure acts on the preload application section 32, the piezoelectric element This is to prevent 31 from floating from the electrode portions 34 and 35 and being unable to measure. Another object is that a shock wave is generated when abnormal combustion occurs in the engine, and the piezoelectric element 31 is lifted by the shock wave and is damaged by colliding with the inner wall surface 33j of the case 33 and the electrode portions 34 and 35. This is to prevent this.

  Here, in the preload application section 32, the case 33, the electrode sections 34 and 35, and the preload application material 37 are made of, for example, the same metal material. Since the pressure detection device 1 is exposed to a high temperature, it is preferable that each component is formed of the same metal material so as not to cause a difference in the coefficient of thermal expansion of each component. The preload application unit 32 is also required to have high pressure resistance and high Young's modulus (hard). For this reason, the case 33, the electrode portions 34 and 35, and the preload application material 37 are formed of, for example, SUS630. Other metal materials such as SUH660 may be used.

  The preload application unit 32 is housed in the hollow portion 23 of the diaphragm 20 and is fixed to the diaphragm 20. Specifically, the preload application unit 32 is disposed in the hollow portion 23 of the diaphragm 20 with a clearance with respect to the inner wall surface 26 of the support portion 21 of the diaphragm 20. Further, the lid portion 33 c of the case 33 is in contact with the pressure receiving portion 22 of the diaphragm 20.

  Furthermore, the preload application section 32 is accommodated in the support section 21 so that the preload receiving section 33 f contacts the inner wall surface 26 of the support section 21 of the diaphragm 20. And the preload application material 37 of the preload application part 32 is being fixed to the opening part 27 of the diaphragm 20 by welding. That is, the preload application material 37 is fixed to the diaphragm 20 by the welded portion 42. Therefore, the case 33 of the preload application unit 32 is fixed to the same potential as the engine block via the diaphragm 20 and the housing 10. The potential of the engine block is, for example, a ground potential.

  In the above configuration, a signal line (not shown) is passed through the housing 10. One end of the signal line is disposed in the through hole 37 a of the preload applying material 37 and the hollow portion of the insulating ring 36 and is electrically connected to the second electrode portion 35. The other end of the signal line is electrically connected to a connector portion (not shown) provided in the housing 10.

  The above is the overall configuration of the pressure detection device 1 according to the present embodiment. According to the above configuration, the impact generated in the combustion chamber is applied to the diaphragm 20. Thereby, the impact of the diaphragm 20 is transmitted to the piezoelectric element 31 via the case 33 and the first electrode portion 34. The piezoelectric element 31 generates an electric charge according to the magnitude of the applied load. Thereby, the voltage between the 1st electrode part 34 and the 2nd electrode part 35 changes. Therefore, the change in the voltage is output to the outside through the signal line.

  Next, a manufacturing method of the pressure detection device 1 will be described. First, an aging process is performed. Specifically, the piezoelectric element 31, the case 33, the electrode portions 34 and 35, the insulating ring 36, and the preload application material 37 are prepared. And the 1st electrode part 34, the piezoelectric element 31, the 2nd electrode part 35, the insulating ring 36, and the preload application material 37 are arrange | positioned in order in the hollow part 33a of the case 33. FIG.

  Further, as shown in FIG. 3, a cylindrical receiving jig 50 is prepared. Of the opening end 51 of the receiving jig 50, the corner on the hollow portion 52 side is chamfered in a tapered shape. Then, the case 33 is inserted into the hollow portion 52 of the receiving jig 50, and the preload receiving portion 33 f of the cylindrical portion 33 b of the case 33 is received and hooked on the tapered portion of the jig 50. As a result, the case 33 floats in the hollow portion 52 of the receiving jig 50.

  Subsequently, a load is applied to the preload application material 37. That is, the preload application material 37 is pushed into the lid 33 c side of the case 33. Specifically, the electrodes 34 and 35 are pressed against the piezoelectric element 31 by applying a higher load to the preload application material 37 than the load based on the impact that would occur in the combustion chamber. As a result, a load is generated at the contact portion between the first electrode portion 34 and the piezoelectric element 31 and at the contact portion between the piezoelectric element 31 and the second electrode portion 35. On the other hand, when a load is applied to the piezoelectric element 31 and the electrode portions 34 and 35 inside the case 33, the cylindrical portion 33b of the case 33 extends along the load application direction.

  In this state, laser welding is performed on the welding area 33h of the cylindrical portion 33b of the case 33. Thereby, the preload application material 37 is fixed to the case 33 by the welded portion 41.

  After welding, the load applied to the preload application material 37 is released as shown in FIG. At this time, a reaction force of a load applied to the piezoelectric element 31, the electrode portions 34 and 35, and the insulating ring 36 is generated. This reaction force is applied to the cylindrical portion 33 b of the case 33. However, since the preload receiving portion 33f receives the load applied to the preload applying material 37, the extension range of the cylindrical portion 33b after releasing the load remains within the range of the preload receiving portion 33f in the load applying direction.

  Thereby, since a load higher than that at the time of actual use is applied to the preload holding unit 30 in advance, sufficient aging can be performed. Furthermore, since the preload holding unit 30 and the diaphragm 20 are separated, there is an advantage that a high load can be applied to the preload holding unit 30 when the preload holding unit 30 is manufactured.

  Thereafter, the pressure receiving portion 22 of the diaphragm 20 is brought into contact with the lid portion 33c of the case 33, and the preload holding portion 30 is moved so that the preload receiving portion 33f comes into contact with the inner wall surface 26 of the support portion 21 of the case 33. 20 is pressed into the hollow portion 23. In this state, laser welding is performed at a position corresponding to the preload applying material 37 on the outer wall surface 24 of the diaphragm 20. Thereby, the preload application material 37 is fixed to the diaphragm 20 by the welded portion 42.

  Then, one end of the signal line and the second electrode portion 35 are electrically connected, and the protruding portion 25 of the diaphragm 20 is laser welded to the opening end of the housing 10. Thereby, the diaphragm 20 is fixed to the housing 10 with the welded portion 40. Further, the other end of the signal line is connected to the connector portion of the housing 10. Thus, the pressure detection device 1 is completed.

  Next, the effect by providing the preload receiving part 33f in the cylinder part 33b of the case 33 is demonstrated. First, in the configuration in which the cylindrical portion 33b of the case 33 is not provided with the preload receiving portion 33f, the lid portion 33c is placed on the receiving jig 60 and the preload applying material 37 is loaded as shown in FIG. Will be multiplied. At this time, a load is applied to the piezoelectric element 31, the electrode portions 34 and 35, and the insulating ring 36, but no load is applied to the portion of the cylindrical portion 33 b of the case 33 except for the preload receiving portion 33 f. In this state, the case 33 is laser welded to the preload application material 37.

  As shown in FIG. 6, when the load applied to the preload application material 37 is released, the load applied to the piezoelectric element 31, the electrode portions 34 and 35, and the insulating ring 36 becomes a reaction force. Applied to the cylindrical portion 33b. For this reason, the extension range of the cylindrical portion 33b after releasing the load is a range from the bottom surface 33i of the case 33 to the welded portion 41 in the load application direction. It has been clarified by the inventors that the preload loss due to the elongation of the cylindrical portion 33b is 80%.

  On the other hand, in the configuration in which the preload receiving portion 33 f is provided in the cylindrical portion 33 b of the case 33, the preload receiving portion 33 f receives the load applied to the preload applying material 37. For this reason, when the load of the preload application material 37 is released, the load applied to the piezoelectric element 31, each electrode part 34, 35, and the insulating ring 36 becomes a repulsive force, and the preload receiving part in the load application direction. It takes a range of 33f. In this way, by receiving the load by the preload receiving portion 33f, the extension range of the cylindrical portion 33b when the load of the preload applying material 37 is released can be shortened. According to the study by the inventors, it has been found that the preload loss due to the elongation of the cylindrical portion 33b is 10%.

  As described above, by providing the preload receiving portion 33f on the cylindrical portion 33b of the case 33, it is possible to reduce the preload drop compared to the configuration in which the preload receiving portion 33f is not provided. That is, the strength of the pressure detection device 1 with respect to the pressure can be secured high. Therefore, since a sufficient preload is applied to the piezoelectric element 31, it is possible to prevent the piezoelectric element 31 from being broken due to the lifting of the piezoelectric element 31 from the electrode portions 34 and 35.

  Then, the effect of being accommodated in the diaphragm 20 so that the preload receiving part 33f may contact the inner wall surface 26 of the support part 21 of the diaphragm 20 is demonstrated.

  First, in a configuration in which the cylindrical portion 33b of the case 33 is not provided with the preload receiving portion 33f, as shown in FIG. 7, the welded portion 42 with respect to the diaphragm 20 serves as a fulcrum. For this reason, the case 33 vibrates with the welded portion 42 as a fulcrum. Accordingly, since the distance from the welded portion 42 to the lid portion 33c is long, the case 33 is greatly shaken.

  On the other hand, in the configuration in which the cylindrical portion 33b of the case 33 is provided with the preload receiving portion 33f and the preload receiving portion 33f is in contact with the inner wall surface 26 of the support portion 21 of the diaphragm 20, as shown in FIG. The preload receiving portion 33f serves as a fulcrum for vibration. For this reason, the case 33 vibrates using the preload receiving portion 33 f that contacts the inner wall surface 26 of the support portion 21 of the diaphragm 20 as a fulcrum. That is, the vibration portion of the case 33 can be shortened compared to the case where the preload receiving portion 33 f does not contact the diaphragm 20. That is, the shaking of the case 33 can be reduced. Therefore, the resonance frequency of the structure including the case 33 can be increased, and consequently the combustion pressure in the high frequency band can be measured. For example, it is possible to detect engine knocking at 52 kHz.

  Regarding the correspondence between the description of the present embodiment and the description of the claims, the first electrode portion 34 and the second electrode portion 35 correspond to the “electrode portion” in the claims.

(Second Embodiment)
In the present embodiment, parts different from the first embodiment will be described. As shown in FIG. 9, in the present embodiment, the preload receiving portion 33f is provided intermittently on the outer wall surface 33e of the cylindrical portion 33b. As described above, the preload receiving portion 33f may not be provided continuously. FIG. 9 is a plan view of the case 33 as viewed from the lid portion 33c side to the cylindrical portion 33b side.

(Other embodiments)
The configuration of the pressure detection device 1 shown in each of the above embodiments is an example, and is not limited to the configuration shown above, and may be another configuration that can realize the present invention. For example, the preload receiving portion 33 f may not be in contact with the inner wall surface 26 of the diaphragm 20.

  Further, the case 33 may not be provided with the welding area 33h. That is, the end of the preload receiving portion 33 f may be located at the opening end 33 g of the case 33. Furthermore, the cross-sectional shape of the preload receiving portion 33f is not limited to a triangular shape, and may be a cross-sectional shape such as a square shape or a trapezoidal shape.

31 Piezoelectric element 33 Case 33b Tube portion 33c Lid portion 33d Tube portion opening 33e Tube portion outer wall surface 33f Preload receiving portion 34, 35 Electrode portion 37 Preload application material

Claims (5)

A pressure detection device that is attached to a combustion mechanism constituting a combustion chamber and detects a combustion pressure in the combustion chamber,
One end of the hollow cylindrical tube portion (33b) is closed by the lid portion (33c), and the other open portion (33d) of the cylindrical portion (33b) is open. Case (33);
A piezoelectric element (31) that is housed in the cylindrical portion (33b) and detects a pressure based on the combustion pressure;
Electrode portions (34, 35) that are housed in the cylindrical portion (33b) and sandwich the piezoelectric element (31);
The piezoelectric element (31) and the electrode portions (34, 35) are fixed to the other opening (33d) in a state where the piezoelectric element (31) and the electrode portions (34, 35) are pushed toward the lid (33c). A preload applying material (37) that applies a preload to the electrode portions (34, 35) and press-contacts the electrode portions (34, 35) and the piezoelectric element (31);
With
The case (33) is provided so as to protrude from the outer wall surface (33e) of the cylindrical part (33b), and the piezoelectric element (31) and the electrode part via the preload application material (37). (34, 35) having a preload receiving portion (33f) for receiving a load applied to the preload applying material (37) when being pushed into the lid portion (33c). Detection device.   The said preload receiving part (33f) is continuously provided in the outer wall surface (33e) of the said cylinder part (33b) so that the said outer wall surface (33e) may be made a round. The pressure detection apparatus described in 1.   The pressure detection device according to claim 1, wherein the preload receiving portion (33f) is provided intermittently on an outer wall surface (33e) of the cylindrical portion (33b). A bottomed cylindrical diaphragm having a hollow cylindrical support portion (21) and a pressure receiving portion (22) to which the combustion pressure is applied and which closes one opening of the support portion (21) ( 20)
In the case (33), the lid portion (33c) is in contact with the pressure receiving portion (22), and the preload receiving portion (33f) is in contact with the inner wall surface (26) of the support portion (21). The pressure detection device according to any one of claims 1 to 3, wherein the pressure detection device is accommodated in the support portion (21).   The cylindrical portion (33b) is disposed on the side of the opening end (33g) of the other opening portion (33d) of the outer wall surface (33e) with respect to the preload receiving portion (33f). The pressure detection device according to any one of claims 1 to 4, further comprising a welding area (33h) for welding the pipe portion to the cylindrical portion (33b).

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