JP7612456B2 - Pressure Measuring Device - Google Patents

Description

The present invention relates to a pressure measuring device that has a sensor chip and a substrate in the internal space of a body.

One example of a conventional pressure measuring device is described in Patent Document 1. The pressure measuring device disclosed in Patent Document 1 comprises a body having a pressure receiving part at one end that receives the pressure of the fluid to be measured, a pressure sensor that is connected to the pressure receiving part via a pressure-conducting pipe and detects the pressure of the fluid to be measured, and a circuit board on which a circuit for processing the electrical signal from the pressure sensor is provided. The pressure sensor and the circuit board are housed inside the body. The pressure sensor is located adjacent to the pressure receiving part, and the circuit board is located at the other end of the body so that the pressure sensor is located between the pressure receiving part and the circuit board.

Patent No. 4955394

The pressure measuring device shown in Patent Document 1 requires space within the body to mount the pressure sensor and space within the body to mount the circuit board, which causes the body to become large.

The object of the present invention is to provide a pressure measuring device whose body can be made compact.

In order to achieve this object, the pressure measuring device according to the present invention is a pressure measuring device having a pressure sensor chip that detects pressure by receiving the pressure of a pressure transmission medium filled between the pressure receiving diaphragm and the pressure receiving diaphragm, and a sensor case that houses the pressure sensor chip, which is installed in the internal space of the body, and the sensor case is made of an insulating material and has an opening for introducing the pressure of the pressure transmission medium into the pressure sensor chip, and the body has the pressure receiving diaphragm formed as a part of the wall and houses a part of the pressure transmission medium. A pressure path is provided from the pressure transmission chamber to the internal space of the body, and the internal space of the body is provided with a stainless steel washer with a through hole attached to the open end of the pressure path that is connected to the internal space of the body, a thin tube filled with the pressure transmission medium, one end of which is inserted and joined to the through hole of the washer and the other end of which passes through the opening of the sensor case and communicates with the pressure sensor chip, and a circuit board on which an electrical circuit that generates an electrical signal from the detection output of the pressure sensor chip is mounted, and the sensor case is mounted on the circuit board.

In the pressure measuring device of the present invention, the circuit board may have a notch at an end through which the thin tube passes, and the sensor case may be placed on the periphery of the notch on the circuit board.

In the pressure measuring device of the present invention, the circuit board may be fixed to the body with the direction in which the opening end of the pressure guide path points being the thickness direction, and a through hole may be formed in the circuit board at a position opposite to the opening end of the pressure guide path.
In the pressure measuring device of the present invention, the circuit board may be fixed to the body with the thickness direction being perpendicular to the direction in which the opening end of the pressure path is pointed, and the thin tube may be bent so that one end connected to the washer is perpendicular to one end connected to the sensor case.

The present invention may be such that soldering lands connected to the electric circuit are provided on the three sides of the circuit board surrounding the hole of the notch, and electrode pads that are connected to the soldering lands and are conductive are provided on the bottom surface of the sensor case, which is the mounting surface that is placed on the circuit board.

In the present invention, the sensor case can be mounted on the circuit board, minimizing the space occupied by the circuit board and the sensor case, and the circuit board and the sensor case can be arranged compactly within the body. Therefore, it is possible to provide a pressure measuring device whose body can be made smaller.

FIG. 1 is a cross-sectional view of a pressure measuring device according to the present invention. FIG. 2 is a perspective cross-sectional view of the pressure measuring device. FIG. 3 is an exploded perspective view showing the body and the resin case of the pressure measuring device with the body and the resin case cut away. FIG. 4 is a perspective cross-sectional view of the pressure sensor assembly. FIG. 5 is an enlarged cross-sectional view showing a joint between the sensor case and the pressure sensor chip and the thin tube. FIG. 6 is an enlarged cross-sectional view showing a joint between the washer and the thin tube. FIG. 7 is a plan view of the pressure sensor assembly and substrate. FIG. 8 is a perspective view of the pressure sensor assembly and the substrate. FIG. 9 is a perspective cross-sectional view for explaining a procedure for welding the washer to the body. FIG. 10 is a plan view of a substrate according to the second embodiment. FIG. 11 is an enlarged plan view showing a main portion of the substrate. FIG. 12 is a perspective view of the pressure sensor assembly and the substrate. FIG. 13 is a perspective view of the pressure sensor assembly and the substrate. FIG. 14 is a diagram showing a substrate according to the third embodiment. FIG. 15 is a perspective view of the pressure sensor assembly.

(First embodiment)
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pressure measuring device according to the present invention will now be described in detail with reference to FIGS.
The pressure measuring device 1 shown in Fig. 1 is configured by assembling a plurality of functional parts, which will be described later, to a body 2 depicted in the center of Fig. 1. The body 2 has a pressure receiving section 3 depicted on the lower side of Fig. 1, and a detection section 4 depicted on the upper side. The body 2 in this embodiment is formed from stainless steel.

1, the pressure-receiving section 3 is formed in a plate shape with its thickness direction being the left-right direction, and one end in the thickness direction is connected to a first pipe 5, and the other end in the thickness direction is connected to a second pipe 6. The inside of the first pipe 5 is filled with a first process fluid 7 to be measured. The inside of the second pipe 6 is filled with a second process fluid 8 to be measured.
One end of the pressure-receiving section 3 that is connected to the first piping 5 is provided with a first pressure-receiving diaphragm 11 that receives the pressure of the first process fluid 7, and a first pressure transmission chamber 12 is formed in which this first pressure-receiving diaphragm 11 forms part of the wall.
The other end of the pressure-receiving section 3, which is connected to the second pipe 6, is provided with a second pressure-receiving diaphragm 13 that receives the pressure of the second process fluid 8, and a second pressure transmission chamber 14 is formed in which this second pressure-receiving diaphragm 13 forms part of the wall.

As shown in FIG. 2, the first pressure transmission chamber 12 and the second pressure transmission chamber 14 are connected to the pressure chamber 24 (see FIG. 5) of the pressure sensor chip 23 via the first pressure guide path 15 and the second pressure guide path 16 formed in the body 2, the first and second washers 17, 18 of the detection unit 4 described below, and the first and second capillaries 21, 22. The pressure transmission system from the first and second pressure transmission chambers 12, 14 to the pressure chamber 24 is filled with a pressure transmission medium 25 (see FIGS. 1 and 5). The pressure sensor chip 23 detects pressure by receiving the pressure of the pressure transmission medium 25 filled between the first and second pressure receiving diaphragms 11, 13.

The detection unit 4 of the body 2 is formed in a cylindrical shape and opens in the direction opposite to the pressure-receiving unit 3. An internal space 26 of the body 2 is formed within the detection unit 4. A cover 27 (see FIG. 1 ) is attached to and closes the opening of the detection unit 4.
3, first and second pressure guide paths 15, 16 are respectively opened to the inner bottom of the detection portion 4. The first and second pressure guide paths 15, 16 are formed inside the body 2 so as to communicate from the first and second pressure transmission chambers 12, 14 to an internal space 26 of the body 2.

As shown in FIG. 2, a first washer 17 is attached to the open end of the first pressure passage 15 that leads to the internal space 26. A second washer 18 is attached to the open end of the second pressure passage 16 that leads to the internal space 26. The first and second washers 17 and 18 are each made of stainless steel and are formed into a disk shape, and are welded to the body 2.

As shown in FIG. 6, the first and second washers 17 and 18 have protrusions 17a and 18a at their centers that face the insides of the first and second pressure guide paths 15 and 16, and through holes 28 and 29 are formed. As shown in FIG. 4, one end of a first capillary tube 21 (described later) is inserted and joined into the through hole 28 of the first washer 17. One end of a second capillary tube 22 (described later) is inserted and joined into the through hole 29 of the second washer 18.

The first capillary tube 21 and the second capillary tube 22 are each made of stainless steel and bent into a predetermined shape. The first and second capillary tubes 21, 22 are joined to the first and second washers 17, 18 by welding the outer peripheries of the tips of the capillary tubes 21, 22 to the opening edges of through holes 28, 29 that open into the protrusions 17a, 18a. This welding is performed so that the welded parts 30 provide a liquid-tight seal between the first and second washers 17, 18 and the first and second capillary tubes 21, 22, as shown in FIG. 6.
The first capillary tube 21 welded to the first washer 17 and the second capillary tube 22 welded to the second washer 18 form part of a pressure sensor assembly designated by the reference numeral 31 in FIG.

As shown in FIG. 4, the pressure sensor assembly 31 is composed of the first and second washers 17, 18 joined to one end of the first and second capillaries 21, 22, and the sensor case 32 and pressure sensor chip 23 joined to the other end of the first and second capillaries 21, 22. The first and second capillaries 21, 22 extend from the first and second washers 17, 18 in the opposite direction to the pressure receiving portion 3 of the body 2, and are bent so that the gap between the first and second washers 17, 18 and the sensor case 32 becomes narrow. The gap between the first and second capillaries 21, 22 is wider at one end welded to the first and second washers 17, 18, and narrower at the other end joined to the sensor case 32.

The sensor case 32 is composed of a case body 33 made of a ceramic material and a lid 34 made of a ceramic material or a metal material. The pressure sensor chip 23 is formed into a cube by stacking a plurality of silicon plate-like members in the thickness direction, and is housed in the sensor case 32.
The case body 33 of the sensor case 32 is formed in a bottomed rectangular tube shape that opens upward in the direction opposite to the pressure-receiving portion 3 of the body 2 in Fig. 4. The lid body 34 is formed in a plate shape and is fixed to the case body 33 by brazing or seam welding in a state in which the opening of the case body 33 is closed. The operation of joining the lid body 34 to the case body 33 is performed so that the inside of the case body 33 is hermetically sealed with a vacuum or filled with _N2 .

4, a plurality of electrode pads 35 are formed on the bottom surface of the sensor case 32, i.e., on the outer surface of the case at the bottom wall 33a of the case main body 33, to be electrically connected to a plurality of terminals (not shown) of the pressure sensor chip 23. The electrode pads 35 according to this embodiment are disposed on both ends of the bottom wall 33a in a direction perpendicular to the direction in which the first capillary tube 21 and the second capillary tube 22 are aligned.
These electrode pads 35 are soldered to soldering lands 37 formed on a substrate 36 (see FIG. 3). By this soldering, the sensor case 32 is electrically connected (mounted) to the soldering lands 37 in a state in which it is placed on the substrate 36. In this embodiment, the substrate 36 corresponds to the "circuit board" of the present invention.

As shown in Fig. 3, the substrate 36 is formed in a disk shape. Two circular through holes 38, 38 through which the first and second washers 17, 18 can pass are formed in the substrate 36, and a slit 39 connecting these through holes 38 to each other is formed. As shown in Fig. 2, the through hole 38 is formed in a position on the substrate 36 opposite the open ends of the first and second pressure guide paths 15, 16.

The sensor case 32 is placed on the substrate 36 by passing the first and second washers 17, 18 through the through holes 38, 38 and passing the first and second thin tubes 21, 22 through the slits 39. As shown in Figs. 7 and 8, the substrate 36 is equipped with an electric circuit 40 that generates an electric signal from the detection output of the pressure sensor chip 23 and a connector terminal 41 for external connection. Although not shown, the substrate 36 is formed with a wiring pattern that electrically connects the soldering land 37 and the electric circuit 40, and a wiring pattern that electrically connects the electric circuit 40 and the connector terminal 41. The positions at which the electric circuit 40 and the connector terminal 41 are mounted are not limited to those shown in the figures and can be changed as appropriate.

The substrate 36 in this embodiment is supported by a resin case 51 (see FIG. 3) and is supported by the body 2 via the resin case 51. The resin case 51 is formed in a cylindrical shape with a bottom that can be accommodated in the internal space 26 of the body 2. The resin case 51 is formed with a mounting surface 52 on which the substrate 36 is placed, a tab 53 for placing and locking the substrate 36 on the mounting surface 52, and two through holes 54, 54 for passing the first and second washers 17, 18 through them.

Around the through hole 54, there are two circular protrusions 55, 55 that protrude downward in FIG. 3 from the bottom wall 51a of the resin case 51, i.e., in a direction toward the pressure-receiving portion 3 of the body 2, and two cylindrical bodies 56, 56 that protrude from the bottom wall 51a of the resin case 51 in a direction opposite the pressure-receiving portion 3. The circular protrusions 55 fit into a circular recess 57 formed in the body 2 so as to surround the first and second pressure guide paths 15, 16. The cylindrical body 56 has a recess 58 formed therein for passing the first and second capillaries 21, 22 through.

When the substrate 36 is attached to the resin case 51, the first and second washers 17, 18 are welded to the body 2, so that the substrate 36 is fixed to the body 2 with the thickness direction of the substrate 36 being the up-down direction in FIG. 1. The up-down direction in FIG. 1 is the direction in which the open ends of the first and second pressure guide paths 15, 16 are oriented.

As shown in FIG. 5, a mounting seat 61 for supporting both sides of the pressure sensor chip 23 is formed on the bottom wall 33a of the case body 33, and first and second openings 62, 63 (see FIG. 4) for introducing the pressure of the pressure transmission medium 25 into the pressure sensor chip 23 are also formed.
4, the pressure sensor chip 23 is formed with a first hole 64 into which the other end of the first capillary tube 21 is inserted and a second hole 65 into which the other end of the second capillary tube 22 is inserted, and is fixed to the mounting seat 61 of the case body 33 by, for example, brazing. The pressure sensor chip 23 is configured to detect the differential pressure between the pressure of the pressure transmission medium 25 transmitted to the first hole 64 and the pressure of the pressure transmission medium 25 transmitted to the second hole 65.

The first and second openings 62, 63 of the case body 33 are formed as through holes penetrating the bottom wall 33a. The hole diameters of the first and second openings 62, 63 are large enough to allow the other ends of the first and second capillaries 21, 22 to pass through. The other end of the first capillary 21 passes through the first opening 62 and is inserted into the first hole 64 of the pressure sensor chip 23, and is connected to the pressure sensor chip 23. The other end of the second capillary 22 passes through the second opening 63 and is inserted into the second hole 65 of the pressure sensor chip 23, and is connected to the pressure sensor chip 23.

As shown in FIG. 5, the first and second capillaries 21, 22 are bonded to the pressure sensor chip 23 by an adhesive 66. An epoxy adhesive can be used as the adhesive 66. The inside of the sensor case 32 is in a state where the epoxy adhesive does not absorb moisture. This state is a vacuum state or a state filled with an inert gas such as _N2 gas. In order to keep the inside of the sensor case 32 in such an inert state, the portions of the first and second capillaries 21, 22 that pass through the first and second openings 62, 63 of the sensor case 32 are sealed by soldering. The soldering is performed so that the solder 67 spreads over the entire area around the first and second openings 62, 63.

The first and second openings 62, 63 of the case body 33 are metallized to enable this soldering. In addition, the first and second capillaries 21, 22 are plated for soldering at the portions that are to be soldered to the first and second openings 62, 63. This plating for soldering is Au plating on a Ni base.

Next, the procedure for assembling the pressure measuring device 1 configured as described above will be described. When assembling the pressure measuring device 1, first, plating for soldering is applied to the parts to be soldered to the first and second openings 62, 63 of the first and second capillaries 21, 22. Note that the parts to which the first and second openings 62, 63 of the case body 33 and the lid 34 are joined are metallized in advance.

Then, the first and second washers 17, 18 are welded to the first and second capillaries 21, 22. After that, the first and second capillaries 21, 22 are passed through the first and second openings 62, 63 of the case body 33, and the first and second capillaries 21, 22 are bonded to the pressure sensor chip 23. The pressure sensor chip 23 is then joined to the case body 33, and the pressure sensor chip 23 and the conductive portion of the case body 33 are connected by, for example, a bonding wire (not shown).

After the pressure sensor chip 23 is attached to the sensor case 32 in this manner, the first and second capillaries 21, 22 are soldered to the first and second openings 62, 63 of the case body 33 to seal the capillary penetrations. The case body 33 and the first and second capillaries 21, 22 are then loaded into a joining device (not shown), and the inside of the case body 33 is made inactive and the lid 34 is attached to the case body 33 by brazing or seam welding. The lid 34 is joined to the case body 33 to complete the pressure sensor assembly 31.

Next, the pressure sensor assembly 31 is attached to the board 36. This attachment is performed by passing the first and second washers 17, 18 through the through holes 38 of the board 36, passing the first and second capillaries 21, 22 through the slits 39, and soldering the sensor case 32 to the board 36. The board 36 is then engaged with the resin case 51, which is then inserted into the internal space 26 of the body 2. When assembling the board 36 to the resin case 51, the position of the board 36 is adjusted so that the first and second washers 17, 18 enter the through holes 54 of the resin case 51 while visually checking the first and second washers 17, 18 through the through holes 38 of the board 36. Then, the circular protrusion 55 of the resin case 51 is fitted into the circular recess 57 of the body 2, and the protrusions 17a and 18a of the first and second washers 17 and 18 are inserted into the first and second pressure guide paths 15 and 16.

Next, the first and second washers 17, 18 are welded to the body 2. As shown in Fig. 9, this welding is performed by resistance welding with the body 2 placed on the lower electrode 71 and the upper electrode 72 pressed against the first and second washers 17, 18. The upper electrode 72 is formed in a rod shape, and is passed through the through hole 54 of the resin case 51 and the through hole 38 of the substrate 36 and overlapped on the first and second washers 17, 18. A slit 73 is formed at the tip of the upper electrode 72 to allow the first and second capillaries 21, 22 to pass therethrough.
After the first and second washers 17, 18 are welded to the body 2, the pressure transmission path extending from the first and second pressure transmission chambers 12, 14 to the inside of the pressure sensor chip 23 is filled with the pressure transmission medium 25. This filling is performed using a filling hole (not shown) extending from the first and second pressure transmission chambers 12, 14 to the outside of the body 2.

The sensor case 32 of the pressure measuring device 1 configured in this manner is placed on the substrate 36. Therefore, since the sensor case 32 can be mounted on the substrate 36, the space occupied by the substrate 36 and the sensor case 32 can be minimized, and the substrate 36 and the sensor case 32 can be compactly arranged within the body 2. Therefore, according to this embodiment, it is possible to provide a pressure measuring device whose body can be made smaller.

Second Embodiment
The substrate and pressure sensor assembly can be configured as shown in Figures 10 to 13. In Figures 10 to 13, the same or equivalent members as those described in Figures 1 to 9 are designated by the same reference numerals and detailed description thereof will be omitted as appropriate.
The substrate 81 shown in Fig. 10 is formed in a disk shape and has two through holes 38 and a notch 82 located at one location on the outer periphery. The two through holes 38, 38 are formed in the same positions as in the first embodiment, that is, in positions facing the open ends of the first and second pressure guide paths 15, 16. In addition, an electric circuit 40 and a connector terminal 41 are mounted on the substrate 81. The positions at which the electric circuit 40 and the connector terminal 41 are mounted are not limited to the positions shown in Fig. 10 and can be changed as appropriate.

The notch 82 is for passing the first and second capillaries 21, 22, and is formed at the radial end of the disk-shaped substrate 81, and extends from the outer periphery 81a of the substrate 81 toward the center. The notch 82 in this embodiment extends in a direction perpendicular to the imaginary line L connecting the centers of the two through holes 38. Therefore, the notch 82 extends toward the center between one through hole 38 and the other through hole 38. The notch 82 also has first and second sides 82a, 82b extending from the outer periphery 81a of the substrate 81 toward the imaginary line L, and a third side 82c extending parallel to the imaginary line L so as to connect one end of these two sides, and is formed so that the opening portion is surrounded by these first to third sides 82a to 82c.

As shown in FIG. 11, a plurality of soldering lands 83 are formed in the portion of the substrate 81 that forms the first side 82a of the notch 82. A plurality of soldering lands 84 are formed in the portion of the substrate 81 that forms the second side 82b of the notch 82. A plurality of soldering lands 85 are formed in the portion of the substrate 81 that forms the third side 82c of the notch 82. These soldering lands 83-85 are connected to the electric circuit 40 mounted on the substrate 81 by a wiring pattern (not shown). The sensor case 32 is mounted on these soldering lands 83-85. That is, the sensor case 32 is placed and fixed on the periphery of the notch 82 on the substrate 81 with the first and second capillaries 21, 22 passing through the notch 82.

If the soldering lands 83-85 are concentrated near one side of the notch 82, stress concentration will occur when an external force is applied to the sensor case 32 during the process of manufacturing the pressure measuring device, or when thermal stress occurs in the solder due to changes in the surrounding temperature. In addition, the area of the bonding surface of each of the electrode pads 35 on the sensor case 32 side will be small, making the process more difficult and reducing the solder strength of the electrode pads 35. To prevent such problems from occurring, in this embodiment, the soldering lands 83-85 are distributed and arranged on the three sides of the notch 82.

The multiple soldering lands 83 provided near the first side 82a and the multiple soldering lands 84 provided near the second side 82b are preferably arranged symmetrically in FIG. 11. Therefore, if the soldering lands 83, 84 are asymmetric, a symmetrical structure is realized by providing unwired dummy soldering lands on the substrate 81 and providing unwired dummy electrode pads on the sensor case 32. In this embodiment, the soldering lands 85 for transmitting the sensor signal are arranged along the third side 82c. By adopting this configuration, the efficiency of mounting the sensor case 32 on the substrate 81 is increased.

The first and second capillaries 21, 22 according to this embodiment are formed by bending as shown in FIG. 12 or FIG.
The first and second capillaries 21 and 22 shown in FIG. 12 each have two bent portions 21 a , 21 b , and 22 b , and are formed in a V-shape when viewed from a direction perpendicular to the main surface 81 b of the substrate 81 .
The first and second capillaries 21, 22 shown in FIG. 13 each have three bent portions 21a to 21c, 22a to 22c, and are formed into an L-shape so as to have a U-shape when viewed from a direction perpendicular to the main surface 81b of the substrate 81.

As shown in this embodiment, by forming a notch 82 at the end of the substrate 81 and placing and fixing the sensor case 32 around the periphery of this notch 82, the slit 39 for passing the first and second capillaries 21, 22 through the substrate 81 is no longer necessary, and the center of the substrate 81 can be used as a component mounting space 86 (see FIG. 10). This makes it possible to mount many electronic components on the substrate 81 without increasing the size of the substrate 81.

Third Embodiment
The substrate and pressure sensor assembly can be constructed as shown in Figures 14(A), (B) and 15. In Figures 14 and 15, the same or equivalent members as those explained in Figures 1 to 13 are given the same reference numerals and detailed explanations are omitted as appropriate. Figure 14(A) is a side view of the substrate as seen from the front side where the sensor case is mounted, and Figure 14(B) is a side view of the substrate as seen from the back side where the sensor case is not mounted. Figures 14(A) and (B) are drawn in a state where the first and second capillaries are not attached to the sensor case.

The substrate 91 shown in Figs. 14(A) and (B) is formed in a rectangular plate shape and has a notch 82 at one end in the longitudinal direction. The four holes 92 provided in the substrate 91 in Figs. 14(A) and (B) are holes for passing mounting bolts (not shown). The mounting bolts secure the substrate 91 to a support bracket on the body 2 side (not shown). The substrate 91 is fixed to the body 2 via the support bracket in such a position that its main surface 91a extends parallel to the longitudinal direction of the body 2 (the direction in which the pressure receiving portion 3 and the detection portion 4 are aligned, which is the vertical direction in Figs. 14(A) and (B)).

In the portion of the substrate 91 where the notch 82 is formed, soldering lands 83 to 85 are provided, as in the second embodiment, and the sensor case 32 is mounted, placed and fixed on these soldering lands 83 to 85.
In this embodiment, the first and second capillaries 21, 22 are bent so that their other ends 95, 96, which are connected to the first and second washers 17, 18, are perpendicular to their one ends 93, 94, which are connected to the sensor case 32, as shown in FIG.

As shown in this embodiment, by arranging the substrate 91 so that it extends parallel to the direction in which the pressure receiving portion 3 and the detection portion 4 of the body 2 are aligned, the detection portion 4 can be formed compactly so that it occupies a small area.

1...pressure measuring device, 2...body, 7...first process fluid, 8...second process fluid, 11...first pressure receiving diaphragm, 12...first pressure transmission chamber, 13...second pressure receiving diaphragm, 14...second pressure transmission chamber, 15...first pressure guide path, 16...second pressure guide path, 17...first washer, 18...second washer, 21...first capillary tube, 22...second capillary tube, 23...pressure sensor Sensor chip, 25...pressure transmission medium, 26...internal space, 28, 29...through holes, 32...sensor case, 35...electrode pads, 36, 81, 91...substrate (circuit board), 40...electrical circuit, 62...first opening, 63...second opening, 82...notch, 38...through holes, 82a...first side, 82b...second side, 82c...third side, 37, 83-85...soldering lands.

Claims (6)

A pressure-receiving diaphragm is provided for receiving the pressure of the process fluid to be measured,
a pressure sensor chip that detects pressure by receiving pressure of a pressure transmission medium filled between the pressure-receiving diaphragm and the pressure sensor chip;
A pressure measuring device having a body in which a sensor case that houses the pressure sensor chip is installed in an internal space,
the sensor case is made of an insulating material and has an opening for introducing the pressure of the pressure transmission medium into the pressure sensor chip;
the body has a pressure passage that is formed as a part of a wall of the pressure-receiving diaphragm and that leads from a pressure transmission chamber that contains a part of the pressure transmission medium to the internal space of the body;
The internal space of the body includes:
a stainless steel washer having a through hole attached to an open end of the pressure guide path that communicates with the internal space of the body;
a thin tube filled with the pressure transmission medium, one end of which is inserted into and joined to the through hole of the washer and the other end of which passes through the opening of the sensor case to communicate with the pressure sensor chip;
a circuit board on which an electric circuit for generating an electric signal from the detection output of the pressure sensor chip is mounted;
The sensor case is placed on the circuit board ,
the circuit board is supported by a resin case having a through hole for receiving the washer therethrough, and is supported by the body via the resin case;
A pressure measuring device, characterized in that the washer is positioned within the through hole of the resin case in a state in which the circuit board is attached to the resin case . 2. The pressure measuring device according to claim 1,
the circuit board has a notch at an end portion through which the thin tube passes;
The pressure measuring device according to claim 1, wherein the sensor case is placed on the circuit board in a peripheral portion of the notch. 3. The pressure measuring device according to claim 2,
the circuit board is fixed to the body in a state in which the direction in which the open end of the pressure guide path faces corresponds to a thickness direction of the circuit board,
A pressure measuring device, comprising: a through hole formed in said circuit board at a position opposite to said open end of said pressure guide path. 3. The pressure measuring device according to claim 2,
the circuit board is fixed to the body in a state where a thickness direction of the circuit board is perpendicular to a direction in which the open end of the pressure guide path is oriented,
A pressure measuring device, wherein the thin tube is bent so that one end connected to the sensor case is perpendicular to the other end connected to the washer. In the pressure measuring device according to any one of claims 2 to 4,
a soldering land connected to the electric circuit is provided on each of the three sides of the circuit board surrounding the hole of the notch;
a bottom surface of the sensor case, which is a mounting surface that is placed on the circuit board, and on which electrode pads are provided that are electrically connected to the soldering lands; 2. The pressure measuring device according to claim 1,
The pressure measuring device according to claim 1, wherein the circuit board is engaged with the resin case by a tab of the resin case.

Images