JP5102802B2 - Manufacturing method of pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor manufacturing method for detecting an in-cylinder pressure of an internal combustion engine.

  Conventionally, a pressure sensor has been used to detect an in-cylinder pressure of an internal combustion engine and perform, for example, knocking detection, combustion pressure peak position detection, misfire detection, and the like. The pressure sensor is, for example, a cylindrical inner case having an annular stepped portion on one end side, and a cylindrical shape that is disposed outside the inner case and has a reduced diameter portion that protrudes radially inward at one end portion. And an outer case. Further, an internal component such as a pressure detection element (for example, a piezoelectric element) is provided in a space formed between the step portion of the inner case and the reduced diameter portion of the outer case (for example, Patent Document 1). reference).

  Here, the above-mentioned pressure sensor is manufactured as follows, for example. That is, internal components such as the pressure detection element are placed on the stepped portion of the inner case. Then, the outer case is disposed on the outer peripheral side of the inner case such that the inner component is sandwiched between the step portion of the inner case and the reduced diameter portion of the outer case. At this time, one end portion of the inner case is inserted into the inner peripheral portion of the reduced diameter portion and protrudes from the reduced diameter portion to one end side. Next, of the inner case, one end portion protruding from the reduced diameter portion is tilted outward in the radial direction (that is, subjected to caulking processing), and a bowl-shaped caulking portion extending outward in the radial direction is provided. Form. And the said pressure sensor is obtained by joining the said crimping part and an outer case (reduced diameter part).

  By the way, when crimping the one end portion of the inner case, a predetermined pressing jig 61 and a receiving jig 71 are used as shown in FIG. The holding jig 61 has a tip surface formed in a flat shape and a tapered portion 62 on the outer peripheral surface of the tip. The receiving jig 71 has an outer peripheral shape similar to the inner peripheral shape of the inner case 81.

  Returning to the explanation of the caulking process at one end of the inner case 81, first, the receiving jig 71 is inserted into the inner case 81, and the inner case 81 and the like are held by the receiving jig 71. Next, the tip of the pressing jig 61 is pushed into the opening at one end of the inner case 81. Thereby, the one end part of the inner case 81 is expanded radially outward by the taper part 62 of the pressing jig 61. And the said crimping part is formed by pressing and deform | transforming the one end part of the inner case 81 with the planarization jig | tool (not shown) which has a flat surface.

JP 2002-168721 A

  However, the holding jig 61 used in the above method has a corner at the tip. Therefore, when the one end portion of the inner case 81 is caulked, the stress from the holding jig 61 concentrates on a portion serving as a bending base point of the inner case 81 and an inner peripheral side portion of the internal component. Will be added. As a result, there is a risk that damage such as cracks and chips will occur in the inner case and the internal components.

  The present invention has been made in view of the above circumstances, and its purpose is to more reliably damage the inner case and the internal components in the pressure sensor manufactured by crimping one end of the inner case. Another object of the present invention is to provide a method of manufacturing a pressure sensor that can be prevented.

  Hereinafter, each configuration suitable for solving the above-described object will be described in terms of items. In addition, the effect specific to the corresponding structure is added as needed.

Configuration 1. The pressure sensor manufacturing method of the present configuration includes a cylindrical outer case having a reduced diameter portion extending in the axial direction and projecting radially inward at one end side;
A cylindrical inner case that is arranged on the inner peripheral side of the outer case and has an annular stepped portion,
An annular internal component disposed between the stepped portion and the reduced diameter portion;
A caulking portion bulging outward in the radial direction formed at one end of the inner case is a method of manufacturing a pressure sensor joined to the reduced diameter portion,
The step of the cylindrical inner case constituting body having the cylindrical main body, the one end having a smaller diameter than the main body, and the step connecting the main body and the one end. The inner component is disposed on the part, and the outer case is disposed on the outer periphery of the inner case component so as to sandwich the inner component between the stepped portion and the reduced diameter portion.
By pushing the tip of the initial holding jig whose outer peripheral surface has a curved surface into the opening of the one end, the opening of the one end is expanded without applying a load to the internal component. An initial expansion step of diameter;
The outer peripheral surface of the tip has a curved surface shape, and the inner end of the internal component is pushed by pushing the tip of the middle-term holding jig having a diameter larger than that of the initial holding jig into the opening of the one end. A medium-term diameter expansion step of further expanding the diameter of the opening at the one end while applying a load to the peripheral portion;
Including applying a pressing force to the one end portion to form the crimped portion, and a final diameter expansion step.
The pressing force in the medium-diameter expanding step is smaller than the pressing force in the final expanding step.

  The “internal component” includes, for example, a pressure detecting element such as a piezoelectric element, an insulating plate for preventing energization between the pressure detecting element and the casing, and an electrode plate disposed on the pressure detecting element. Can be mentioned.

  According to the above-described configuration 1, by pushing the distal end portion of each holding jig into the opening portion at one end portion (the opening portion formed on the one end side of the cylindrical inner case structure), the one end portion is expanded. Although diameter processing is performed, the outer peripheral surface of the tip of the pressing jig (the corner portion between the tip surface and the side surface) has a curved surface shape. Therefore, as compared with the case of using a holding jig having a corner at the tip as in the conventional technique described above, it is possible to more reliably prevent damage to the inner case (inner case constituent body) due to stress concentration. it can.

  In particular, in the initial diameter expanding step, the opening at one end is expanded without applying a load to the internal components. That is, in the initial diameter expansion process, an initial pressing jig having an outer diameter that does not apply a load to the internal components is used, and the opening at one end is not rapidly expanded. Therefore, since the bent portion is formed at the one end of the cylindrical shape, the stress applied to the one end can be reduced in the initial diameter expansion process in which stress concentration and thus the inner case are more likely to be damaged. As a result, it is possible to more reliably prevent the inner case from being damaged such as a crack.

  Further, in the medium-term diameter expansion process, for example, a load is applied to the inner peripheral side portion of the internal component such as a piezoelectric element made of an insulating ceramic or the like. The contact area of the surface is relatively small. Therefore, the pressure (surface pressure) applied to the internal components increases, and there is a concern about damage to the internal components. In this regard, according to the present configuration 1, the pressing force applied to the one end portion in the medium-term diameter expansion step is set to be smaller than the pressing force in the final diameter expansion step. Accordingly, an increase in pressure applied to the internal components can be suppressed, and damage to the internal components can be more reliably prevented.

  By the way, in the said prior art, lubricating oil etc. can be apply | coated to the internal peripheral surface of one end part in order to aim at suppression of the increase in stress. However, in this case, when joining the caulking portion and the reduced diameter portion of the outer case, there is a concern about the decrease in the joint strength due to the presence of the lubricating oil. It becomes necessary. In this regard, according to the present configuration 1, since the diameter of the opening at one end is divided into at least three steps or more, the stress applied to the one end per step is reduced as compared with the conventional technique. Can do. Therefore, it is not necessary to apply lubricating oil or the like for suppressing the increase in stress to the inner peripheral surface of the one end when the diameter of the one end is increased. For this reason, the caulking portion and the reduced diameter portion can be firmly joined without requiring a troublesome work such as removal of the lubricating oil when joining the formed caulking portion and the reduced diameter portion of the outer case. As a result, workability can be dramatically improved.

Configuration 2. The manufacturing method of the pressure sensor of this configuration is the above-mentioned configuration 1, wherein the inner diameter of the opening at the one end before the initial diameter expansion step is D _A (mm),
After the initial diameter step, when the inner diameter of the opening of the end portion before the metaphase enlarged step was D _B (mm),
(D _B −D _A ) / D _A ≦ 0.05
It is characterized by satisfying.

According to the above configuration 2, to the inner diameter D _A of the opening end portion before expanded, enlarged proportion of the inner diameter D _B of the opening of one end after the initial diameter expansion step is 5% or less. Therefore, in the initial diameter expansion process in which stress concentration at one end is more concerned, the stress applied to the one end can be further reduced, and damage to the inner case can be more reliably prevented.

Configuration 3. The manufacturing method of the pressure sensor of this structure is set to _SK (mm < ² >) in the said structure 1 or 2 that the area of the said crimping part to be formed seen from the said axial direction one end side is set,
When the contact area of the tip surface of the holding jig for the medium term with respect to the one end portion in the medium term diameter expansion step is S _C (mm ² ),
S _C / S _K ≦ 0.2
It is characterized by satisfying.

According to the above configuration 3, the area of the crimp portion to be formed as viewed from the axial direction one end side and S _K, and S _C a contact area of the tip surface of the medium-term for the pressing jig against one end of metaphase diameter step In this case, S _C / S _K ≦ 0.2. That is, since the outer diameter of the distal end portion of the middle-stage presser jig that is pushed into the opening at one end portion is relatively small, the stress applied to the one end portion during caulking can be further suppressed. On the other hand, since the contact area S _C is relatively small, there is a further concern about an increase in pressure on the internal components, but by adopting the configuration 1 or the like, the concern can be eliminated. That is, according to the present configuration 3, if the damage to one side is suppressed, there is a concern about the other side damage (if the contact area is reduced, the damage to the inner case can be suppressed, but the pressure on the internal components increases. If the contact area is increased, the pressure on the internal components can be suppressed, but the stress applied to the inner case will increase). Can be prevented more reliably.

Configuration 4. The manufacturing method of the pressure sensor of this configuration is any one of the above-described configurations 1 to 3, in the medium-term diameter expansion step,
A plurality of pressing jigs having different outer diameters at the tip end portions are used as the medium-term pressing jig, and the opening of the one end portion is expanded in a plurality of stages.

  According to the said structure 4, a medium-term diameter expansion process is performed by gradually expanding the opening part of the said one end part over several steps using a some pressing jig. Therefore, the stress applied to the inner case can be effectively reduced, and damage to the inner case can be prevented more reliably.

Configuration 5. The manufacturing method of the pressure sensor of this configuration is any one of the above configurations 1 to 4, in the final diameter expansion step,
A plurality of pressing jigs having different outer diameters at the tip end portions are used as the final pressing jig, and the opening of the one end portion is expanded in a plurality of stages to form the crimped portion.

  According to the said structure 5, in the final diameter expansion process, the said one end part is diameter-expanded in multiple steps by using a some final pressing jig. Therefore, the stress applied to the inner case can be further reduced, and damage to the inner case can be more reliably prevented.

  Configuration 6. The manufacturing method of the pressure sensor of this configuration is characterized in that, in the above configuration 4 or 5, the inner diameter of the opening at the one end is increased by 10% or more and 13% or less.

  According to the configuration 6, when the diameter of the opening at the one end is gradually increased, the inner diameter of the opening is increased by 10% or more and 13 or less. For this reason, it is possible to more reliably prevent damage to the inner case due to a sudden expansion of the opening, and the opening is expanded by at least 10% or more, thereby improving productivity. It becomes possible.

It is sectional drawing which shows the structure of a pressure sensor. It is a partial expanded sectional view which shows the structure of a pressure sensor. It is a disassembled perspective view for demonstrating the manufacturing method of a pressure sensor. It is a partial expanded sectional view which shows the inner case structural body etc. before a diameter expansion process. It is a partial expanded sectional view which shows the 1st holding jig etc. in an initial diameter expansion process. It is a partial expanded sectional view which shows the 2nd holding jig etc. in a medium term diameter expansion process. It is a partial expanded sectional view which shows the 3rd holding jig etc. in a medium term diameter expansion process. It is a partial expanded sectional view which shows the 4th holding jig etc. in the final diameter expansion process. It is a partial expanded sectional view which shows the 5th holding jig etc. in the final diameter expansion process. It is a partial expanded sectional view which shows the 6th holding jig etc. in the final diameter expansion process. It is a partial expanded sectional view which shows the 7th holding jig etc. in the final diameter expansion process. It is a partial expanded sectional view for demonstrating the diameter expansion process of the inner case one end part which concerns on a prior art.

  Hereinafter, an embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the configuration of the pressure sensor 1. As shown in FIG. 1, the pressure sensor 1 is inserted into the plug hole PH of the engine head EH during use, and one end side is formed between the engine head EH (bottom surface of the plug hole PH) and the spark plug SP. It will be arranged in between.

  The pressure sensor 1 includes a cylindrical sensor main body 2 located on one end side, and a cylindrical portion 3 extending from the sensor main body 2 to the other end side along the axis CL1.

  As shown in FIG. 2, the sensor main body 2 includes a casing 4 and an internal component 11 that is housed in the casing 4 in a stacked state. The internal component 11 includes a plate packing 5, a piezoelectric element 6, an electrode plate 7, an insulating plate 8, and an insulating tube 10.

  The casing 4 is formed by combining an inner case 41 and an outer case 42 formed of a metal (for example, SUS) plate material having a predetermined thickness (for example, 0.3 mm).

  The inner case 41 has a cylindrical shape extending along the axis CL <b> 1 and is disposed on the inner peripheral side of the outer case 42. Further, an annular step portion 41A formed so as to be constricted radially inward is provided on one end side of the inner case 41. Furthermore, at one end portion of the inner case 41, a hook-shaped caulking portion 41 </ b> B is formed which is located on one end side in the axis line CL <b> 1 direction relative to one end of the outer case 42 and bulges outward in the radial direction.

  The outer case 42 has a cylindrical shape extending along the axis CL <b> 1 and is disposed on the outer peripheral side of the inner case 41 so as to form a gap with the outer peripheral surface of the inner case 41. Further, at one end portion of the outer case 42, a reduced diameter portion 42A formed so as to protrude radially inward is formed. And the inner case 41 is joined with respect to the outer case 42 by laser-welding the edge part of the said crimped part 41B along the circumferential direction with respect to the said diameter-reduced part 42A. The internal component 11 is disposed in the annular space between the stepped portion 41 </ b> A of the inner case 41 and the reduced diameter portion 42 </ b> A of the outer case 42 in the space in the casing 4.

  The plate packing 5 is formed of a predetermined metal material (for example, SUS) and is disposed on the inner side surface of the reduced diameter portion 42A. In addition, the piezoelectric element 6 is made of a predetermined insulating ceramic material (for example, lead zirconate titanate or lead titanate), and is stacked on the plate packing 5 in a surface contact state.

  Further, the electrode plate 7 is formed in a flat ring shape from a conductive metal material, and is disposed so as to be stacked on the piezoelectric element 6. In addition, one end of a lead wire 9 is electrically connected to the outer peripheral portion of the electrode plate 7. The lead wire 9 is made of a conductive wire covered with an insulating material except for the end portion, passes between the inner case 41 and the outer case 42, and is led to the outside through the cylindrical portion 3.

  In addition, the insulating plate 8 is formed of a predetermined insulating material and is interposed between the electrode plate 7 and the inner case 41. The insulating plate 8 insulates the electrode plate 7 from the inner case 41.

  In addition, the insulating tube 10 is disposed between the inner peripheral surface of the inner case 41 and the piezoelectric element 6 and the like. The insulating tube 10 is formed of a predetermined insulating material (for example, silicon rubber or fluorine rubber) and has a cylindrical shape extending along the axis CL1.

  Next, the manufacturing method of the pressure sensor 1 mentioned above is demonstrated.

First, as shown in FIG. 3, a cylindrical main body 51A, one end 51B having a smaller diameter than the main body 51A, and a step 51C (corresponding to the step 41A) connecting the main body 51A and the one end 51B. And a cylindrical inner case structure 51 to be the inner case 41 is manufactured. The one end 51B has a predetermined inner diameter D _A (for example, 12.0 mm). An internal component 11 such as the plate packing 5 and the piezoelectric element 6 prepared in advance is arranged on the step portion 51C of the inner case component 51, and a reduced diameter portion is formed on the internal component 11 (plate packing 5). The outer case 42 is arranged on the outer peripheral side of the inner case structure 51 so that 42A is positioned. The reduced diameter portion 42A has a predetermined inner diameter D _O (for example, 12.75 mm), and the inner diameters of the plate packing 5 and the piezoelectric element 6 are the inner diameter D _{O of the} reduced diameter portion 42A. This is the above (for example, 12.8 mm).

  Next, a process of forming the crimped portion 41B by tilting the opening of the inner case structural body 51 (one end portion 51B) outward in the radial direction (applying crimping) will be described.

First, as shown in FIG. 4, a cylindrical receiving jig 31 having a cylindrical protrusion 32 at the center of the tip is inserted into the inner case constituting body 51 to hold the inner case constituting body 51 and the like. In the initial diameter expanding step, as shown in FIG. 5, as an initial pressing jig having a hole 21H into which the protrusion 32 can be inserted at the center of the tip and the outer peripheral surface of the tip having a curved surface shape. The first holding jig 21 is used to enlarge the diameter of the opening of the one end 51B. That is, by inserting the protrusion 32 into the hole 21H and pushing the tip of the first pressing jig 21 into the opening of the one end 51B with a predetermined load (for example, 13 kN), The diameter of the opening of the part 51B is increased. Thereafter, the first holding jig 21 is pulled out from the one end 51B. The tip of the first pressing jig 51B is smaller than the inner diameter D _O of the outer case 42, but within 5% (for example, 5%) of the inner diameter D _A of the one end 51B before diameter expansion. ) Is increased in outer diameter D1 (for example, 12.6 mm). Therefore, in the initial diameter expansion process, no pressure is applied to the internal components 11 such as the piezoelectric element 6. The inner diameter D _B of the opening of the end portion 51B that has passed through the initial diameter step, as compared to the inner diameter D _A of the enlarged front end portion 51B and thus are expanded by an amount less than 5%.

  Next, in the medium-term diameter expansion step, as shown in FIGS. 6 and 7, the second pressing jig 22 having a predetermined outer diameter D2 (for example, 14.0 mm) at the front end and a predetermined inner diameter D3 at the front end. Using the third pressing jig 23 having (for example, 15.5 mm), the diameter of the opening of the one end 51B is gradually increased in a plurality of stages (in this embodiment, two stages). That is, by pushing the tip of the second pressing jig 22 into the opening of the one end 51B with a predetermined load (for example, 6 kN), the diameter of the opening of the one end 51B is expanded, and then the first 2 Pull out the holding jig 22. Next, by pushing the tip of the third pressing jig 23 into the opening of the one end 51B with a predetermined load (for example, 6 kN), the diameter of the opening of the one end 51B is increased, and the third pressing jig 23 is pressed. Pull out the tool 23. Here, the pressing load by the second and third pressing jigs 22 and 23 is smaller than the pressing load by the fourth to seventh pressing jigs 24 to 27 described later (for example, half or less). . The second and third pressing jigs 22 and 23 have a curved outer peripheral surface similar to the first pressing jig 21. The holding jigs 22 and 23 have hole portions 22H and 23H having the same shape as the hole portion 21H at the center of the tip, and when the diameter of the one end portion 51B is expanded, The protrusion 32 is to be inserted into the holes 22H and 23H. The second and third pressing jigs 22 and 23 correspond to a medium-term pressing jig.

  In the present embodiment, the outer diameter D2 of the second pressing jig 22 is larger by 10% or more and 13% or less than the outer diameter D1 of the first pressing jig. The outer diameter D3 of the pressing jig 23 is larger than the outer diameter D2 of the second pressing jig 22 by 10% to 13% (for example, 10% to 12%). Therefore, the inner diameter of the one end 51B is also increased by 10% or more and 13% or less.

In addition, in the medium-term diameter expansion step, the area when the caulking portion 41B to be formed is viewed from one end side in the axis CL1 direction is S _K (mm ² ), and the second holding jig 22 with respect to the one end portion 51B. when the contact area of the front end surface and S _C2 (mm ^2), the contact area of the distal end surface of the third press jig 23 against one end 51B and the ^{_{S C3 (mm 2), S}} C2 / S K ≦ 0. 1 and S _C3 / S _K ≦ 0.2. In other words, in the medium-term diameter expansion process, the contact area of the tip surfaces of the holding jigs 22 and 23 with respect to the one end 51B is relatively small.

  Next, in the final diameter increasing step, as shown in FIGS. 8, 9, 10, and 11, the tip end portion has a predetermined outer diameter, and the tip outer peripheral surface is similar to the pressing jigs 21 to 23. The opening of the one end 51B is enlarged using the fourth pressing jig 24, the fifth pressing jig 25, the sixth pressing jig 26, and the seventh pressing jig 27 having a curved surface shape, The caulking portion 41B is formed. That is, as shown in FIGS. 8 and 9, the small diameter portion 51B is obtained by inserting / removing the tip portions of the fourth and fifth pressing jigs 24, 25 in this order with respect to the opening portion of the one end portion 51B. The diameter is gradually increased. Then, as shown in FIGS. 10 and 11, the hook-like caulking that bulges outward in the radial direction by pressing the one end 51B with the tip surfaces of the sixth and seventh pressing jigs 26 and 27. A portion 41B is formed, and the inner case 41 is configured. The fourth to seventh pressing jigs 24 to 27 correspond to the final pressing jig.

  Further, in the final diameter increasing step, the outer diameters D4 and D5 of the tip ends of the fourth and fifth pressing jigs 24 and 25 are 10% larger than the outer diameters D3 and D4 of the third and fourth pressing jigs 23 and 24. The diameter of the opening of the one end 51B is increased by 10% or more and 13% or less by increasing the diameter by 13% or less or by appropriately changing the pressing load by the holding jigs 24 to 27. ing. However, the pressing force (load) applied to the one end 51B by the fourth to seventh pressing jigs 24 to 27 is the pressing force applied from the second and third pressing jigs 22 and 23 in the medium-term diameter expansion process. In comparison, it is large (for example, 13 kN to 17 kN). Further, the fourth to seventh pressing jigs 24 to 27 have holes 24H, 25H, 26H, and 27H, respectively, at one end central portions, similarly to the pressing jigs 21 to 23 described above, and one end 51B. When the diameter is increased, the protrusion 32 is inserted into the holes 24H to 27H.

  Next, the inner case 41 is joined to the outer case 42 by laser welding the outer peripheral edge portion of the crimped portion 41B and the reduced diameter portion 42A of the outer case 42 along the circumferential direction. A pressure sensor 1 is obtained. Note that silicon rubber or the like may be filled between the inner case 41 and the outer case 42.

  As described above in detail, according to the present embodiment, the diameter of the one end 51B is increased by pushing the tip of each pressing jig 21 to 27 into the opening of the one end 51B. The outer peripheral surfaces of the tips of the holding jigs 21 to 27 have a curved surface shape. Therefore, as compared with the case of using a pressing jig having a corner at the tip as in the conventional technique described above, damage to the inner case 41 (inner case structure 51) due to stress concentration is more reliably prevented. be able to.

  In particular, in the initial diameter expansion process, the opening of the one end 51B is expanded without applying a load to the internal component 11. That is, in the initial diameter expansion process, the first pressing jig 21 having an outer shape that does not apply a load to the internal component 11 is used, and the opening of the one end 51B is not rapidly expanded. . Accordingly, since the bent portion is formed in the cylindrical one end portion 51B, the stress applied to the one end portion 51B can be reduced in the initial diameter expansion process in which stress concentration and thus the inner case 41 are more likely to be damaged. . As a result, it is possible to more reliably prevent the inner case 41 from being damaged such as a crack.

Furthermore, in the medium-term diameter expansion step, a load is applied to the inner peripheral side portion of the internal component 11 such as the piezoelectric element 6. At this time, S _C2 / S _K ≦ 0.1 and S _C3 / S The contact area of the tip surfaces of the second and third pressing jigs 22 and 23 with respect to the one end 51B is relatively small so as to satisfy _K ≦ 0.2. Therefore, the pressure (surface pressure) applied to the internal component increases, and there is a concern about damage to the internal component. However, according to the above-described embodiment, the pressure is applied to the one end 51B in the medium-term diameter expansion process. The pressing force to be applied is smaller than the pressing force applied to the one end 51B in the final diameter expanding step. Therefore, an increase in pressure applied to the internal component 11 can be suppressed, and damage to the internal component 11 can be more reliably prevented.

  Further, since the stress applied to the one end 51B can be suppressed by expanding the opening of the one end 51B in at least three stages (in this embodiment, seven stages), the one end 51B is intended to reduce the stress. There is no need to apply lubricating oil or the like to the inner peripheral surface of the. For this reason, when joining the formed caulking part 41B and the reduced diameter part 42A of the outer case 42, the caulking part 41B and the reduced diameter part 42A are more reliably connected without requiring a troublesome work such as removal of lubricating oil. In addition, it is possible to join more firmly, and as a result, it is possible to dramatically improve workability.

Furthermore, to the inner diameter D _A of the opening of the one end portion 51B before expanded, after the initial diameter step, expanded ratio of the inner diameter D _B of the opening of the end portion 51B in the prometaphase expanded process is 5% or less ing. Therefore, in the initial diameter expansion step, the stress applied to the one end 51B can be more effectively suppressed, and damage to the inner case 41 can be prevented more reliably.

  In addition, the medium-term diameter expansion process and the final diameter expansion process are performed by gradually increasing the diameter of the opening of the one end 51B over a plurality of stages using the plurality of holding jigs 22 to 27. Therefore, the stress applied to the inner case (one end portion 51B) can be effectively reduced, and damage to the inner case 41 can be more reliably prevented. Further, when the diameter of the one end 51B is increased stepwise, the diameter expansion ratio of the opening of the one end 51B is set to 10% or more and 13% or less. Therefore, it is possible to more reliably prevent damage to the inner case 41 due to the rapid expansion of the opening, and the opening is expanded by at least 10% or more, thereby improving productivity. be able to.

  Further, when the diameter of the one end 51B is increased, the protrusion 32 provided on the receiving jig 31 is inserted into the holes 21H to 27H of the pressing jigs 21 to 27. Therefore, the diameter of the one end 51B can be increased uniformly without unevenness, and as a result, the crimped portion 41B can be accurately formed. For this reason, it is possible to join the crimped portion 41B to the reduced diameter portion 42A without shifting in the radial direction, and as a result, it is possible to improve the appearance quality and the bonding strength.

  In addition, it is not limited to the description content of the said embodiment, For example, you may implement as follows. Of course, other application examples and modification examples not illustrated below are also possible.

  (A) In the above embodiment, in the initial diameter expansion step, the opening of the one end 51B is expanded using the first pressing jig 21 (that is, in one stage). If it is set as the structure which does not apply pressing force to the internal component 11, it is good also as performing an initial diameter expansion process using a some pressing jig (namely, dividing into several steps).

  Further, in the medium-term diameter expansion step, the second and third pressing jigs 23 and 24 are used, that is, divided into two stages, and the diameter of the opening of the one end 51B is increased. In, it is good also as expanding the diameter of the opening part of the one end part 51B in 1 step | paragraphs or multistage | paragraphs of 3 steps or more.

  In addition, in the final diameter expanding step, the fourth to seventh pressing jigs 24 to 27 are used, that is, divided into four stages to expand the opening of the one end 51B. The diameter of the opening of the one end portion 51B in the process may be divided into fewer stages or more stages.

  That is, in consideration of various factors such as the shape and strength of the inner case 41 and the piezoelectric element 6, the number of diameter expansion steps of the one end portion 51B in the initial diameter expansion process, the medium period diameter expansion process, and the final diameter expansion process is appropriately changed. It is good as well.

(B) In the above embodiment, in the medium-term diameter expansion step, the contact areas S _C2 and S _{C3 of the} tip surfaces of the second pressing jigs 22 and 23 with respect to the one end 51B are S _C2 / S _K ≦ 0.1, and Although it is configured to satisfy S _C3 / S _K ≦ 0.2, the contact area of the tip surfaces of the second and third pressing jigs 22 and 23 with respect to the one end 51B may not satisfy the above formula. Good.

  (C) In the above embodiment, the internal component 11 is constituted by the plate packing 5, the piezoelectric element 6 and the like, but the members constituting the internal component 11 are not limited to these.

DESCRIPTION OF SYMBOLS 1 ... Pressure sensor 21 ... 1st pressing jig 22 ... 2nd pressing jig 23 ... 3rd pressing jig 24 ... 4th pressing jig 25 ... 5th pressing jig 26 ... 6th pressing jig 27 ... 7th Holding jig 41 ... Inner case 41A ... Step part 41B ... Casting part 42 ... Outer case 42A ... Reduced diameter part 51 ... Inner case structure 51A ... Main body part 51B ... One end part 51C ... Step part CL1 ... Axis

Claims (6)

A cylindrical outer case having a reduced diameter portion extending in the axial direction and projecting radially inward on one end side;
A cylindrical inner case that is arranged on the inner peripheral side of the outer case and has an annular stepped portion,
An annular internal component disposed between the stepped portion and the reduced diameter portion;
A caulking portion bulging outward in the radial direction formed at one end of the inner case is a method of manufacturing a pressure sensor joined to the reduced diameter portion,
The step of the cylindrical inner case constituting body having the cylindrical main body, the one end having a smaller diameter than the main body, and the step connecting the main body and the one end. The inner component is disposed on the part, and the outer case is disposed on the outer periphery of the inner case component so as to sandwich the inner component between the stepped portion and the reduced diameter portion.
By pushing the tip of the initial holding jig whose outer peripheral surface has a curved surface into the opening of the one end, the opening of the one end is expanded without applying a load to the internal component. An initial expansion step of diameter;
The outer peripheral surface of the tip has a curved surface shape, and the inner end of the internal component is pushed by pushing the tip of the middle-term holding jig having a diameter larger than that of the initial holding jig into the opening of the one end. A medium-term diameter expansion step of further expanding the diameter of the opening at the one end while applying a load to the peripheral portion;
Including applying a pressing force to the one end portion to form the crimped portion, and a final diameter expansion step.
A pressure sensor manufacturing method, wherein a pressing force in the medium-term diameter expansion step is made smaller than a pressing force in the final diameter expansion step. The inner diameter of the opening at the one end before the initial diameter expansion step is D _A (mm),
After the initial diameter step, when the inner diameter of the opening of the end portion before the metaphase enlarged step was D _B (mm),
(D _B −D _A ) / D _A ≦ 0.05
The method for manufacturing a pressure sensor according to claim 1, wherein: The area of the caulking portion to be formed as seen from one end side in the axial direction is S _K (mm ² ),
When the contact area of the tip surface of the holding jig for the medium term with respect to the one end portion in the medium term diameter expansion step is S _C (mm ² ),
S _C / S _K ≦ 0.2
The method for manufacturing a pressure sensor according to claim 1, wherein: In the medium-term diameter expansion step,
4. The method according to claim 1, wherein a plurality of holding jigs having different outer diameters at the tip end portions are used as the middle-stage holding jig, and the opening of the one end portion is expanded in a plurality of stages. The manufacturing method of the pressure sensor of description. In the final diameter expansion step,
A plurality of pressing jigs having different outer diameters at the tip end portions are used as a final pressing jig, and the opening portion of the one end portion is expanded in a plurality of stages to form the crimped portion. The manufacturing method of the pressure sensor in any one of 1-4.   6. The method of manufacturing a pressure sensor according to claim 4, wherein the inner diameter of the opening at the one end is increased by 10% or more and 13% or less.

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