JP6498965B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor.

  Patent Document 1 discloses a pressure sensor configured to digitally display the pressure of a fluid to be measured measured by a pressure detection element. Such a pressure sensor has, for example, a configuration in which components such as a circuit board on which a pressure detection element is mounted and a liquid crystal display member are stacked and accommodated in a casing including a front case and a base member.

Japanese Patent Laid-Open No. 10-142900

  By the way, in the pressure sensor as described above, the circuit board on which the pressure detection element is mounted serves as a part that supports the pressure detection element that receives the pressure of the fluid to be measured, and therefore can withstand high pressure from the fluid to be measured. Thus, it is necessary to be firmly fixed to the casing or the like. For this reason, as a method of fixing the circuit board on which the pressure detection element is mounted to the casing or the like, there is a fact that a screwing method or a heat caulking method capable of reliable fixing has to be adopted. However, the screwing method and the heat caulking method are time-consuming operations and hinder the simplification of the pressure sensor assembly operation.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a pressure sensor that can be easily assembled.

  A pressure sensor for achieving the above object is a pressure sensor for detecting the pressure of a fluid to be measured, and includes a base member having an introduction portion for introducing the fluid to be measured, and the fluid to be measured introduced from the introduction portion. A pressure detection element that detects the pressure of the base member, a circuit board that is stacked on the base member and on which the pressure detection element is mounted, and a base member that is disposed on the opposite side of the base member across the circuit board. A fixing member that sandwiches the circuit board therebetween, and the fixing member is provided with a holding portion that extends toward the base member, and between the holding portion and the base member, An inner engagement portion is provided to fix the base member and the fixing member by engaging a part of the member with the other member, and the base member is disposed outside the inner engagement portion. The inner engagement portion A cover member for restricting the deformation of the portion provided is mounted and fixed.

  According to the above configuration, the base member, the circuit board, and the fixing member are sequentially stacked, and the fixing member disposed on the opposite side of the base member across the circuit board and the base member are engaged by the inner engagement portion. The circuit board can be fixed to the fixing member by a simple operation of making it happen. Further, by positioning the cover member fixed to the base member outside the inner engagement portion, the deformation of the portion where the inner engagement portion is provided, specifically, the deformation in the direction of opening outward is regulated. . When the engagement state of the inner engagement portion is released, there is always a deformation in the direction of opening outward at the portion where the inner engagement portion is provided. The engagement of the inner engagement portion is difficult to be released. As a result, the fixing member and the base member are fixed by engagement with the circuit board interposed therebetween, but a strong fixing structure capable of withstanding the pressure from the fluid is obtained.

  In the above configuration, as the inner engagement portion, an engagement claw provided on the holding portion and protruding toward the base member side, an engagement recess provided on the base member and engaged with the engagement claw, Further, the holding portion is provided with an auxiliary engagement concave portion that opens to the base member side adjacent to the base end side of the engagement claw, and the base member includes the auxiliary engagement It is preferable that an auxiliary engagement claw inserted into the recess is provided.

  In this case, in order to release the engagement of the inner engagement portion, the inner engagement is greater than or equal to the sum of the engagement width of the engagement claw and the engagement recess and the engagement width of the insertion recess and the auxiliary engagement claw. The part where the joint is provided must be deformed. Therefore, it becomes difficult to release the engagement of the inner engagement portion. Moreover, compared with the case where one of the engagement claws and the auxiliary engagement claws is omitted and only one engagement claw is provided, the same engagement width can be ensured with a length of about half the claw. . Therefore, it is possible to provide the inner engagement portion in a smaller space, and the degree of freedom in designing the pressure sensor is improved. In particular, the pressure sensor can be easily downsized.

  The said structure WHEREIN: It is preferable that the attachment part for fixing the attachment auxiliary tool for attaching the said pressure sensor to an attachment object is provided in the said cover member. In particular, it is preferable that the attachment portion is provided on a wall portion located outside the inner engagement portion in the cover member.

  In this case, in the state where the attachment assisting tool is attached, the attachment assisting tool is located outside the cover member. Therefore, when the portion provided with the inner engagement portion is about to be deformed in the direction of opening outward, the cover member is less likely to be deformed following the same direction. As a result, the effect of restricting the deformation of the portion where the inner engagement portion is provided by the cover member is enhanced.

  In the above-described configuration, an outer engagement portion between the base member and the cover member that engages a part of one side member with the other side member to fix the base member and the cover member. It is preferable that the outer engagement portion is provided on the same surface as the surface of the base member on which the inner engagement portion is provided.

  In this case, in the assembly process, when stacking the fixing members and attaching the cover member, it is only necessary to work with the surfaces on which the inner engagement portion and the outer engagement portion are provided facing the same side. Can be assembled easily.

The said structure WHEREIN: It is preferable that the said base member is provided with the flange located facing the edge part of the said cover member.
In this case, something unexpectedly catches on the end of the cover member, and it is difficult for the cover member to be detached from the base member.

The said structure WHEREIN: It is preferable that the recessed part for removal in which a jig | tool is inserted when removing the said cover member from the said base member is provided in the said flange.
In this case, even when the cover member is firmly fixed to the base member in order to increase the strength of the fixing structure by the inner engagement portion, the cover member can be easily removed from the base member by using a jig. be able to. By making the part for removal into the concave part, something unexpectedly catches on the part for removal, and it is difficult for the cover member to be detached from the base member.

  In the above-described configuration, the base member is positioned on the base member side edge of the cover member at a position overlapping with a portion of the cover member located outside the inner engagement portion in the direction along the edge. It is preferable that the protrusion part which protrudes in the side is provided.

  In this case, the distance from the part which overlaps with the inner engaging part in a cover member to the same edge part becomes long. Therefore, when the portion provided with the inner engagement portion is about to be deformed in the direction of opening outward, the cover member is less likely to be deformed following the same direction. As a result, the effect of restricting the deformation of the portion where the inner engagement portion is provided by the cover member is enhanced.

  According to the pressure sensor of the present invention, assembly work can be easily performed.

The perspective view of a pressure sensor. The disassembled perspective view of some pressure sensors (a base member, a circuit board, and a diffusion member). The perspective view of a part (a base member, a circuit board, and a diffusion member) of a pressure sensor. The exploded perspective view of a pressure sensor. FIG. 5 is an end view taken along line 5-5 in FIG. 1. FIG. 6 is an end view taken along line 6-6 of FIG. FIG. 7 is an end view taken along line 7-7 in FIG. 1. Explanatory drawing regarding attachment of a pressure sensor.

Hereinafter, an embodiment in which the present invention is embodied in a pressure sensor including a liquid crystal display member will be described.
As shown in FIGS. 1 and 2, the pressure sensor 10 includes a base member 20 made of synthetic resin. The base member 20 includes a square plate-like rear wall 21, a first inner wall 22 standing along two opposite sides on the one side of the rear wall 21, and two opposite sides on the other side of the rear wall 21. Are formed in the shape of a bottomed square box having a second inner wall 23 erected along the wall.

  A flange 24 protruding from the first inner wall 22 and the second inner wall 23 is provided at the peripheral edge of the rear wall 21. In addition, a recess 24 a is provided at the center of each side of the flange 24. A cylindrical inlet 21a for taking in a fluid to be measured is provided at the center of the rear wall 21. Further, the rear wall 21 is provided with a connector hole 21b by notching one side thereof.

  As shown in FIGS. 2 and 5, an engagement groove 25 extending from the edge on the opening side is provided at the center of the outer surface of the first inner wall 22. The engagement groove 25 is provided with an engagement recess 25 a that extends along the opening edge of the first inner wall 22 and penetrates the first inner wall 22. The engaging groove 25 is provided with an auxiliary engaging claw 25b that protrudes outward along the edge of the engaging recess 25a. The auxiliary engagement claw 25b is formed in a substantially triangular shape in cross section that gradually becomes wider toward the engagement recess 25a.

  As shown in FIGS. 2 and 6, two engagement protrusions 22 a are provided on the outer surface of the first inner wall 22 so as to be located on both sides of the engagement groove 25 in the direction along the opening edge. Yes. And in the flange 24 of the 1st inner wall 22, the recessed part 26 for removal is provided in the position which overlaps with each engaging protrusion 22a.

  As shown in FIGS. 2 and 5 to 7, a circuit board 30 having a detection circuit and the like for detecting pressure is formed on the first inner wall 22 and the second inner wall 23 of the base member 20. Has been placed. The outer shape of the circuit board 30 is formed so as to substantially match the outer peripheral shape of the first inner wall 22 and the second inner wall 23 of the base member 20. A recess 30 a corresponding to the engagement groove 25 provided in the inner wall 22 is provided.

  A pressure detection element 31 is mounted at the center of the lower surface of the circuit board 30 (the surface on the base member 20 side). As shown in FIGS. 5 and 7, the pressure detection element 31 includes a cylindrical introduction portion 31 a that protrudes toward the base member 20, and an O-ring 32 is interposed between the introduction portion 31 a and the base member 20. It is attached. An external connection connector 33 is attached to the lower surface of the circuit board 30. The distal end portion of the external connection connector 33 is fitted in the connector hole 21 b of the base member 20. In addition, in each end view shown in FIGS. 5-7, components attached to the circuit board 30, such as the pressure detection element 31 and the connector for external connection 33, are shown in a simplified manner.

  As shown in FIGS. 2 to 7, a diffusion member 40 and a liquid crystal display member 50 that displays a detection result by the pressure detection element 31 are sequentially stacked on the upper surface side (the side opposite to the base member 20) of the circuit board 30. Has been placed. In the present embodiment, the diffusing member 40 corresponds to a fixing member.

  The diffusion member 40 is a member made of a synthetic resin material having a square plate shape having an outer shape substantially the same as that of the circuit board 30. In the central portion of the diffusing member 40, a long rectangular diffusion opening 41 is provided. As shown in FIG. 3, a display (backlight) light emitting element 34 such as an LED attached to the circuit board 30 is located in the opening of the diffusion opening 41. The diffusion member 40 diffuses the light from the light emitting element 34 toward the liquid crystal display member 50 in the diffusion opening 41.

  As shown in FIGS. 3 and 7, a connector insertion hole extending along the long side 41 a is provided between the long side 41 a on one side of the diffusion opening 41 in the diffusion member 40 and the peripheral part of the diffusion member 40. 42 is formed through the diffusion member 40. An elastic connector 35 for electrically connecting the liquid crystal display member 50 to the circuit board 30 is inserted into the connector insertion hole 42. The elastic connector 35 is a member formed in a flat plate shape by alternately overlapping conductive rubber and insulating rubber having elasticity, one end of which is connected to an electrode provided on the circuit board 30 and the other end The side is connected to the electrode portion of the liquid crystal display member 50.

  As shown in FIGS. 3 and 7, in the diffusing member 40, on the side opposite to the connector insertion hole 42 across the diffusing opening 41, in the vicinity of the center of the long side 41 b on the other side of the diffusing opening 41. An elastic support portion 43 for supporting the liquid crystal display member 50 is integrally formed at the site. The elastic support portion 43 is a portion that is formed in a bridge shape in which long rectangular plate portions are connected at two points on both ends thereof and can be bent in the vertical direction (thickness direction).

  More specifically, a slit 44 extending along the long side 41b on the other side of the diffusion opening 41 is provided on the diffusion opening 41 side of the elastic support 43, and the diffusion opening of the elastic support 43 is provided. On the side opposite to 41, a step portion 45 is provided that is one step lower in the vertical direction (thickness direction) than the elastic support portion 43. By the slit 44 and the stepped portion 45, the elastic support portion 43 is formed in a bridge shape in which long rectangular plate-like portions are connected at two points on both ends thereof. And the flexibility is improved because the lower surface side (circuit board 30 side) of the elastic support part 43 is thinned. Furthermore, a bulging portion 43 a that bulges upward (on the side opposite to the circuit board 30) is provided at the center of the elastic support portion 43.

  As shown in FIG. 6, a portion of the diffusing member 40 that is lowered by the stepped portion 45 is a button mounting portion 46 for attaching a button member 60 described later. Further, a support wall 47 erected on the upper side (opposite side of the circuit board 30) and a holding piece 48 erected on the lower side (circuit board 30 side) are provided on the periphery of the diffusion member 40. Yes. In the present embodiment, the holding piece 48 corresponds to a holding portion.

  As shown in FIGS. 2 and 3, the holding piece 48 is a rectangular plate provided at the center of two sides located on the same side as the first inner wall 22 of the base member 20 at the periphery of the diffusing member 40. And is accommodated in an engagement groove 25 provided on the first inner wall 22 of the base member 20. An engagement claw 48 a that protrudes toward the inner surface is provided at the inner tip of the holding piece 48. The engaging claw 48 a is formed in a substantially triangular shape in cross section that gradually becomes wider toward the proximal end side of the holding piece 48. Further, an auxiliary engagement recess 48 b penetrating the holding piece 48 is provided on the proximal end side of the engaging claw 48 a in the holding piece 48.

  As shown in FIG. 5, the engagement claw 48 a provided on the holding piece 48 is inserted into the engagement recess 25 a provided on the first inner wall 22 of the base member 20. The auxiliary engagement claw 25 b provided on the first inner wall 22 is inserted into the auxiliary engagement recess 48 b provided on the holding piece 48. In the present embodiment, an inner engagement portion is configured by the engagement claw 48a and the engagement recess 25a, and the auxiliary engagement claw 25b and the auxiliary engagement recess 48b.

  As shown in FIGS. 4 to 7, a liquid crystal display member 50 and a button member 60 are disposed on the upper surface side (the side opposite to the circuit board 30) of the diffusion member 40. The liquid crystal display member 50 is a member having a long rectangular shape as a whole, and is disposed so as to overlap the diffusion opening 41 of the diffusion member 40. As shown in FIG. 7, an electrode portion is formed over the entire one long side of the back surface of the liquid crystal display member 50, and this electrode portion is connected to the elastic connector 35 protruding from the connector insertion hole 42 of the diffusion member 40. Has been. Further, the central portion on the other long side of the back surface of the liquid crystal display member 50 is in contact with the bulging portion 43 a of the elastic support portion 43 in the diffusing member 40. Accordingly, the entire rear surface of the liquid crystal display member 50 is supported by the elastic connector 35 and the central portion of the other long side is supported by the elastic support portion 43.

  As shown in FIGS. 1 and 4, the pressure sensor 10 includes a synthetic resin cover member 70 that covers the outside of the base member 20. The cover member 70 includes a square plate-like front wall 71, a first outer wall 72 erected from two opposing sides on the one side of the front wall 71, and two opposing sides on the other side of the front wall 71. It is formed in a bottomed square box shape having a second outer wall 73 provided.

  The front wall 71 is provided with a window portion 71a for allowing the liquid crystal display member 50 to be visually recognized. As shown in FIG. 5 to FIG. 7, a transparent cover 71 b that covers the window 71 a is attached to the inside of the front wall 71, and the transparent cover 71 b comes into contact with the liquid crystal display member 50, and the liquid crystal display member 50. The liquid crystal display member 50 is fixed between the transparent cover 71 b, the elastic connector 35, and the elastic support portion 43. Further, the front wall 71 is provided with a button opening 71 c for exposing the button portion of the button member 60.

  As shown in FIG. 4, the first outer wall 72 and the second outer wall 73 of the cover member 70 both have an elongated rectangular shape, and a protruding portion 74 that protrudes toward the opening edge side is provided at the center portion on the opening edge side. ing. The first outer wall 72 is provided with two outer engaging recesses 72a penetrating the first outer wall 72 so as to be located on both sides of the protrusion 74 in the direction along the opening edge. Further, on both sides of the outer surface of the second outer wall 73 on the front wall 71 side, two first mounting portions 75a having a groove shape are provided, and at the center of the outer surface of the first outer wall 72 on the opening edge side. Is provided with a second mounting portion 75b having a groove shape.

  As shown in FIGS. 5 and 6, the first outer wall 72 of the cover member 70 is located outside the first inner wall 22 of the base member 20 and the holding piece 48 of the diffusion member 40, and the first inner wall 22 and It is in contact with or close to the holding piece 48. Further, as shown in FIGS. 1 and 4 to 6, the opening side edges of the first outer wall 72 and the second outer wall 73 in the cover member 70 are positioned so as to face the flange 24 of the base member 20. The first outer wall 72 and the second outer wall 73 are substantially flush with the peripheral surface of the flange 24. The protrusions 74 provided on the first outer wall 72 and the second outer wall 73 are inserted into the recesses 24 a provided on the flanges 24 of the first inner wall 22 and the second inner wall 23 of the base member 20. ing. As shown in FIG. 7, the protrusion 74 of the first outer wall 72 overlaps with a portion of the first outer wall 72 located outside the holding piece 48 in the direction along the edge on the opening side. Is provided. In addition, as shown in FIG. 6, the engagement protrusion 22 a provided on the first inner wall 22 of the base member 20 is inserted into the outer engagement recess 72 a provided on the first outer wall 72. In the present embodiment, the outer protrusion is constituted by the engagement protrusion 22a and the outer engagement recess 72a.

Next, an example of the assembly process of the pressure sensor 10 of this embodiment is demonstrated.
First, the circuit board 30 on which components such as the pressure detection element 31 and the external connection connector 33 are mounted is stacked on the first inner wall 22 and the second inner wall 23 of the base member 20. At this time, as shown in FIG. 5, an O-ring 32 is attached between the introduction portion 31 a of the pressure detection element 31 attached to the circuit board 30 and the base member 20, and an external connection attached to the circuit board 30. The distal end portion of the connector 33 is fitted into the connector hole 21 b of the base member 20.

  Thereafter, the diffusion member 40 is further stacked on the circuit board 30 so that the holding piece 48 of the diffusion member 40 is positioned in the engagement groove 25 provided in the first inner wall 22 of the base member 20. At this time, as shown in FIG. 5, while the holding piece 48 is elastically deformed and opened outward, the engaging claw 48 a of the holding piece 48 is inserted into the engaging recess 25 a of the first inner wall 22 and engaged. At the same time, the auxiliary engagement claw 25b of the first inner wall 22 is inserted into and engaged with the auxiliary engagement recess 48b of the holding piece 48. Thereby, the diffusion member 40 is fixed to the base member 20, and the circuit board 30 is fixed to the base member 20 in such a manner that the diffusion member 40 is sandwiched between the base member 20 and the diffusion member 40.

  Subsequently, the elastic connector 35 is inserted into the connector insertion hole 42 of the diffusion member 40, and the end of the elastic connector 35 is projected from the connector insertion hole 42, so that the elastic connector 35 and the elastic support portion 43 of the diffusion member 40 are The liquid crystal display member 50 is stacked on top. At this time, the liquid crystal display member 50 is positioned on the diffusion member 40 by bringing the edge of the liquid crystal display member 50 into contact with the inner surface of the support wall 47. The button member 60 is attached to the button mounting portion 46 of the diffusing member 40.

  Next, the cover member 70 to which the transparent cover 71b is attached is put on the base member 20 to which the circuit board 30, the diffusion member 40, and the like are attached. At this time, as shown in FIG. 6, the engaging protrusion 22 a provided on the first inner wall 22 of the base member 20 is inserted into and engaged with the outer engaging recess 72 a provided on the first outer wall 72. . At the same time, as shown in FIG. 1, the protrusions 74 provided on the first outer wall 72 and the second outer wall 73 are recessed portions 24 a provided on the first inner wall 22 and the second inner wall 23 of the base member 20. Inserted inside. Thereby, the cover member 70 is attached and fixed to the base member 20.

  Further, as shown in FIG. 7, the liquid crystal display member 50 is fixed by being sandwiched between the transparent cover 71 b attached to the cover member 70 and the elastic connector 35 and the elastic support portion 43 of the diffusing member 40. The button member 60 is fixed by being sandwiched between the diffusion member 40 and the cover member 70. In this way, the assembly of the pressure sensor 10 is completed. The cover member 70 can be easily removed by inserting a jig such as a screwdriver into the removal recess 26 provided in the base member 20 and bending the first outer wall 72 and the second outer wall 73. it can.

Moreover, the pressure sensor 10 of this embodiment is attached to attachment objects, such as a panel, as follows.
As shown in FIG. 8, the pressure sensor 10 is inserted into the attachment port 80 a of the attachment object 80 with the window portion 71 a side of the cover member 70 as the front side. And while attaching the 1st attachment auxiliary tool 81 with respect to the surrounding surface of the part which protrudes from the attachment object 80 in the pressure sensor 10 to the front side, it is the 2nd attachment auxiliary tool with respect to the surrounding surface of the part which protrudes on the back side. 82 is attached.

  The first attachment auxiliary tool 81 has a rectangular frame shape having an outer shape larger than that of the pressure sensor 10, and a first attachment protrusion 81a is provided on one opposing two surfaces on the inner surface side. The first attachment auxiliary tool 81 engages the pressure sensor 10 by engaging the first attachment protrusion 81 a with the first attachment portion 75 a provided on the second outer wall 73 of the cover member 70 of the pressure sensor 10. Fixed.

  The second attachment assisting tool 82 has a rectangular frame shape having an outer shape larger than that of the pressure sensor 10, and a second attachment projection 82a is provided on one opposing two surfaces on the inner surface side. The second attachment assisting tool 82 engages the pressure sensor 10 by engaging the second attachment protrusion 82 a with the second attachment portion 75 b provided on the first outer wall 72 of the cover member 70 of the pressure sensor 10. Fixed.

  By attaching the first attachment assisting tool 81 and the second attachment assisting tool 82, the pressure sensor 10 with respect to the attachment object 80 is restricted from being removed from the front side and the back side, and the pressure sensor is attached to the attachment object 80. 10 is fixed.

Next, the operation of this embodiment will be described.
In the pressure sensor 10 of the present embodiment, a holding piece 48 extending toward the base member 20 is provided with respect to the diffusion member 40 disposed on the opposite side of the base member 20 across the circuit board 30. Then, by engaging inner engagement portions (engagement claw 48a and engagement recess 25a, and auxiliary engagement claw 25b and auxiliary engagement recess 48b) provided between the holding piece 48 and the base member 20, The circuit board 30 is fixed to the base member 20 in such a manner that the diffusion member 40 is fixed to the base member 20 and is sandwiched between the base member 20 and the diffusion member 40. Therefore, the base member 20, the circuit board 30, and the diffusing member 40 are sequentially stacked, and the base member 20 is attached to the base member 20 by a simple operation of engaging the base member 20 and the diffusing member 40 with the inner engagement portion. The circuit board 30 can be fixed.

  Further, in this fixing structure, when the holding piece 48 is deformed in the direction of opening outward and the deformation amount exceeds the engagement width of the inner engagement portion, the engagement of the inner engagement portion is released. Thus, the fixing of the circuit board 30 to the base member 20 is released. The engagement width of the inner engagement portion is the width of the portion of the engagement claw 48a that is locked to the engagement recess 25a and the portion of the auxiliary engagement claw 25b that is locked to the auxiliary engagement recess 48b. Is the sum of the widths.

  Therefore, a part of the cover member 70 (the first outer wall 72) attached to the base member 20 to protect the circuit board 30 and the like is positioned outside the holding piece 48, so that the cover member is opened outward. The deformation is regulated. Thereby, in the state where the cover member 70 is attached, the engagement of the inner engagement portion is difficult to be released. As a result, the circuit board 30 is fixed to the base member 20 in such a manner that the base member 20, the circuit board 30, and the diffusing member 40 are sequentially stacked, and the base member 20 and the diffusing member 40 are engaged with each other by the inner engagement portion. Even though the fixing structure is easy to assemble, it is a strong fixing structure that can withstand the pressure from the fluid to be measured.

Next, the effect of this embodiment will be described.
(1) The pressure sensor 10 that detects the pressure of the fluid to be measured includes a base member 20 having an introduction port 21a for introducing the fluid to be measured, and a pressure detection element that detects the pressure of the fluid to be measured introduced from the introduction port 21a. 31, a circuit board 30 that is stacked on the base member 20 and on which the pressure detection element 31 is mounted, and a circuit board that is disposed on the opposite side of the base member 20 with the circuit board 30 interposed therebetween. And a diffusing member 40 sandwiching 30. The diffusion member 40 is provided with a holding piece 48 extending toward the base member 20, and between the holding piece 48 and the base member 20, a part of one side member is engaged with the other side member, Inner engagement portions (the engagement claws 48a and the engagement recesses 25a, and the auxiliary engagement claws 25b and the auxiliary engagement recesses 48b) that fix the base member 20 and the diffusion member 40 are provided. A cover member 70 that is disposed outside the inner engagement portion and restricts deformation of the holding piece 48 is attached and fixed to the base member 20.

According to the above configuration, the assembling work, particularly the assembling work related to fixing the circuit board 30 to the base member 20 can be easily performed.
(2) As an inner engagement portion, an engagement claw 48a provided on the holding piece 48 and protruding toward the base member 20 side, and an engagement recess 25a provided on the base member 20 and engaged with the engagement claw 48a It has. Further, the holding piece 48 is provided with an auxiliary engaging recess 48b that opens to the base member 20 side adjacent to the base end side of the engaging claw 48a, and the base member 20 has an auxiliary engaging recess 48b. An auxiliary engagement claw 25b to be inserted is provided.

  In the case of the above configuration, in order to release the engagement of the inner engagement portion, the engagement width of the inner engagement portion, that is, the width of the portion locked to the engagement recess 25a in the engagement claw 48a, and the auxiliary The holding piece 48 must be deformed to be equal to or greater than the total width of the portions of the engagement claws 25b that are locked to the auxiliary engagement recesses 48b. Therefore, it becomes difficult to release the engagement of the inner engagement portion.

  Further, according to the above configuration, compared with the case where one of the engagement claws 48a and the auxiliary engagement claws 25b is omitted and only one engagement claw is provided, the length of the claw is about half that of the same degree. A sufficient width can be secured. Therefore, it is possible to provide the inner engagement portion in a smaller space, and the degree of freedom in designing the pressure sensor 10 is improved. In particular, the pressure sensor 10 can be easily downsized.

  (3) The base member 20 is formed in a square box shape having two pairs of first inner wall 22 and second inner wall 23 facing each other, and the inner engagement portion is a first inner wall which is one opposite side wall. 22 and the holding piece 48.

  According to the above configuration, by limiting the portion where the inner engagement portion is provided between the first inner wall 22 of the base member 20 and the holding piece 48, the strength of the fixing structure by the inner engagement portion is secured. The manufacturing cost can be suppressed.

  (4) The second attachment portion 75b that engages with the second attachment assisting tool 82 used when attaching the pressure sensor 10 to the attachment object 80 is used as the first outer wall 72 of the cover member 70, that is, the holding piece of the diffusion member 40. It is provided on the wall portion located outside 48.

  According to the above configuration, the second attachment assisting tool 82 is located outside the first outer wall 72 of the cover member 70 in a state where the second attachment assisting tool 82 is attached. Therefore, when the holding piece 48 of the diffusing member 40 is to be deformed in the direction of opening outward, the cover member 70 is less likely to be deformed following the same direction. As a result, the effect of restricting the deformation of the holding piece 48 by the cover member 70 is enhanced.

  (5) Between the base member 20 and the cover member 70, an outer engaging portion (a part of one side member is engaged with the other side member to fix the base member 20 and the cover member 70). An engagement protrusion 22a and an outer engagement recess 72a) are provided. The outer engagement portion is provided on the same surface as the surface on which the inner engagement portion of the base member 20 is provided.

  According to the above configuration, in the assembly process, when stacking the diffusion member 40 and covering the cover member 70, work is performed with the surfaces on which the inner engagement portion and the outer engagement portion are provided facing the same side. Therefore, it can be easily assembled.

(6) The base member 20 is provided with a flange 24 that faces the edge of the cover member 70 on the base member 20 side.
According to the above configuration, the flange 24 is positioned opposite to the end of the cover member 70, so that something unexpectedly catches on the end of the cover member 70 and the cover member 70 is detached from the base member 20. Is less likely to occur.

(7) The flange 24 is provided with a removal recess 26 into which a jig is inserted when the cover member 70 is removed from the base member 20.
According to the above configuration, even when the cover member 70 is firmly attached to the base member 20 in order to increase the strength of the fixing structure by the inner engagement portion, the cover member 70 can be removed from the base member 20 by using the jig. Can be easily removed. In addition, by making the part to be removed a concave part, something is suddenly caught on the part to be removed, and the cover member 70 is unlikely to be detached from the base member 20.

  (8) At the edge of the first outer wall 72 on the opening side, in the direction along the edge, the base member 20 side is located at a position overlapping the portion of the first outer wall 72 located outside the holding piece 48. The protrusion part 74 which protrudes in is provided.

  According to the said structure, the distance from the part which overlaps with the holding piece 48 in the cover member 70 to the same edge part becomes long. Therefore, when the holding piece 48 tries to deform in the direction of opening outward, the first outer wall 72 is less likely to deform following the same direction. As a result, the effect of restricting the deformation of the holding piece 48 by the cover member 70 is enhanced.

(9) The diffusion member 40 provided in the pressure sensor 10 including the liquid crystal display member 50 is used as a fixing member.
According to the said structure, the increase in a number of parts can be suppressed.

In addition, the said embodiment can also be changed and actualized as follows.
-The concrete structure of an inner side engaging part is not limited to the said embodiment. For example, the auxiliary engagement claw 25b and the auxiliary engagement recess 48b may be omitted, or the engagement claw 48a and the engagement recess 25a may be omitted. Moreover, it is good also as a structure which replaces with the structure which engages a nail | claw and a recessed part, and engages nail | claws.

  -The length of the nail | claw of the engaging claw 48a can be set suitably. Note that, from the viewpoint of ensuring a large engagement width of the inner engagement portion, the tip of the claw of the engagement claw 48a (tip in the protruding direction) is the first inner wall 22 of the base member 20 at the time of engagement. It is preferable that the length matches the position of the inner surface. In terms of downsizing, the length of the claw tip (tip in the protruding direction) of the engagement claw 48a coincides with the position of the inner surface of the first inner wall 22 of the base member 20 at the time of engagement. The following is preferable. Further, the engaging recess 25a with which the engaging claw 48a is engaged need not be a through hole. The same applies to the auxiliary engagement claw 25b.

  The holding member 48 may be provided on the peripheral edge of the diffusing member 40 on the second inner wall 23 side of the base member 20, and the inner engagement portion may be provided between the diffusing member 40 and the second inner wall 23 of the base member 20. .

  -The holding piece 48 (holding part) provided in the diffusion member 40 is not limited to a piece shape. For example, a wall shape standing along a part or all of each side of the diffusing member 40 may be used.

  In the above embodiment, the holding piece 48 provided in the diffusing member 40 is located outside the first inner wall 22 of the base member 20, but may be located inside the first inner wall 22. In this case, the cover member 70 restricts deformation in a direction to open to the outside of the first inner wall 22.

  Although the diffusion member 40 provided in the pressure sensor 10 including the liquid crystal display member 50 is used as a fixing member, a fixing member that forms an inner engagement portion between the base member 20 and the diffusion member 40 is used. It may be provided.

  -You may provide the outer side engaging part provided between the base member 20 and the cover member 70 in a different surface from the surface in which the inner side engaging part in the base member 20 is provided. In this case, the deformation direction of the cover member 70 necessary for releasing the engagement of the outer engagement portion and the deformation direction of the diffusion member 40 required for releasing the engagement of the inner engagement portion ( Since the deformation direction of the holding piece 48 is different, the force in the direction in which the engagement of the inner engagement portion is released does not directly become the force in the direction of releasing the engagement of the outer engagement portion. Therefore, the fixing structure by the engagement of the inner engagement portion becomes stronger.

  The outer engagement portion provided between the base member 20 and the cover member 70 may be omitted. For example, the base member 20 may be composed of a plurality of divided bodies that form an accommodation space therein, and these divided bodies may be engaged with each other.

  -In the cover member 70, you may change the position which provides the 1st attaching part 75a and the 2nd attaching part 75b. If at least one of the first attachment portion 75a and the second attachment portion 75b is provided on the first outer wall 72 of the cover member 70 (the wall portion located outside the holding piece 48 of the diffusion member 40), In the state where the first attachment assisting tool 81 or the second attachment assisting tool 82 is attached, the effect of restricting the deformation of the holding piece 48 by the cover member 70 can be enhanced. In addition, in the viewpoint of obtaining this effect remarkably, the 1st attaching part 75a and the 2nd attaching part 75b are the part located in the outer side of the holding piece 48 in the 1st outer side wall 72, or the opening side rather than the same part. It is preferable to provide at the site.

In place of the synthetic resin base member 20, a metal base member 20 may be used. In this case, an insulating member is disposed between the base member 20 and the circuit board 30.
In the above embodiment, the pressure sensor 10 including the liquid crystal display member 50 is embodied, but the pressure sensor 10 not including the liquid crystal display member 50 may be used. In this case, instead of the diffusing member 40, a fixing member that forms an inner engagement portion with the base member 20 is provided.

  DESCRIPTION OF SYMBOLS 10 ... Pressure sensor, 20 ... Base member, 25 ... Joint groove, 25a ... Engagement recessed part, 25b ... Auxiliary engagement claw, 30 ... Circuit board, 31 ... Pressure detection element, 40 ... Diffusion member (fixing member), 48 ... holding piece (holding part), 48a ... engaging claw, 48b ... auxiliary engaging recess, 70 ... cover member.

Claims (7)

A pressure sensor for detecting a pressure of a fluid to be measured,
A base member having an introduction part for introducing a fluid to be measured;
A pressure detection element for detecting the pressure of the fluid to be measured introduced from the introduction unit;
A circuit board that is stacked on the base member and on which the pressure detection element is mounted;
A fixing member that is disposed on the opposite side of the base member with the circuit board interposed therebetween and holds the circuit board between the base member,
The fixing member is provided with a holding portion extending toward the base member,
Between the holding part and the base member, an inner engagement part is provided that engages a part of one side member with the other side member to fix the base member and the fixing member,
A cover member that is disposed outside the inner engagement portion and restricts deformation of a portion where the inner engagement portion is provided is attached and fixed to the base member ,
As the inner engagement portion,
An engaging claw provided on the holding portion and projecting toward the base member;
An engagement recess provided on the base member and engaged with the engagement claw;
Further, the holding portion is provided with an auxiliary engagement recess opening on the base member side adjacent to the proximal end side of the engagement claw, and the base member is inserted into the auxiliary engagement recess. A pressure sensor characterized in that an auxiliary engaging claw is provided . The pressure sensor according to claim 1, wherein the cover member is provided with an attachment portion for fixing an attachment auxiliary tool for attaching the pressure sensor to an attachment target. The pressure sensor according to claim 2 , wherein the attachment portion is provided on a wall portion located outside the inner engagement portion in the cover member. An outer engagement portion is provided between the base member and the cover member to engage a part of the member on one side with the member on the other side and fix the base member and the cover member,
Wherein the outer engaging portion, the pressure sensor according to any one of claims 1 to 3, characterized in that the inner engaging portion of said base member is provided on the surface and the same plane provided. The pressure sensor according to any one of claims 1 to 4 , wherein the base member is provided with a flange positioned to face an edge of the cover member on the base member side. The pressure sensor according to claim 5 , wherein the flange is provided with a removal recess into which a jig is inserted when removing the cover member from the base member. The edge of the cover member on the base member side protrudes toward the base member at a position overlapping with a portion of the cover member located outside the inner engagement portion in the direction along the edge. The pressure sensor according to any one of claims 1 to 6, wherein a protrusion is provided.