Pressure sensor

Abstract

To provide a pressure sensor that reduces stress applied to a circuit board mounted therein and achieves a structure ensuring fluid-tightness with high accuracy, and can thereby be used with high reliability.SOLUTION: A pressure sensor 100 has a sensor chip 11 that detects the pressure of a measurement object and is connected to a circuit board 50 mounted inside a case 20. The sensor chip is installed in a liquid-sealed chamber LR to receive the pressure of the measurement object, and the circuit board is installed interposed between the sensor chip and an external device A in an installation space SR that is filled with sealant 26 inside the case and formed in a fluid-tight manner. The circuit board is electrically connected to a core wire C of a lead wire 38 lead out to the outside and connected to the external device, and the core wire is covered with a coating 38c up to near the installation space.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pressure sensor that is liquid-tightly molded with resin. [Background technology]

[0002] 2. Description of the Related Art Various sensors for detecting pressure, temperature, etc. are fixed in the vicinity of a measurement object and are used to send a detection signal to a measuring instrument, etc., and are often used either built into the measuring instrument or attached externally.

[0003] These types of sensors are incorporated into sensor units so that they can be installed in locations exposed to the same environment as the object to be measured. For example, a circuit board may be installed inside the sensor chip when it is necessary to change the electrical characteristics input and output to the sensor chip (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6633597 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the pressure sensor described in Patent Document 1, as shown in FIG. 8, a circuit board 1431 connected to a sensor chip 1121 in a housing 1124 is contained in a case 1135, and the case 1135 is filled with a sealing material 1136 such as a resin material to provide a liquid-tight seal.

[0006] In such a structure, when a temperature difference occurs between the inside and outside of the object to be measured, stress corresponding to the temperature difference may occur because there is a difference in the linear expansion coefficient of components such as circuit board 1431, case 1135, and sealing material 1136. This stress may become a load on circuit board 1431 itself and the components mounted on circuit board 1431.

[0007] In addition, such pressure sensors are often used with lead wires that are pulled out so as to be electrically connectable to an external device being connected to a circuit board. For example, in the pressure sensor shown in FIG. 8, lead wire 1433, whose core wire C is conductively connected to circuit board 1431, is pulled out so as to be connectable to an external device.

[0008] In this structure, the case 1135 is sealed liquid-tight by filling with the sealant 1136. However, when the sealant 1136 is filled in a state where the coating 1433c of the lead wire 1433 is in close contact with one side of the circuit board 1431, it is difficult to embed the boundary end where the core wire C is exposed from the lead wire 1433, that is, the coating end, in the sealant 1136 and seal it liquid-tight. In addition, since the lead wire has a structure in which thin-diameter conductors are twisted together, a minute space exists inside the core wire, and the outside air on the external device side and the circuit board part of the pressure sensor communicate through this minute space. For example, in a pressure sensor attached to a refrigerant pipe in a refrigeration cycle, the temperature change of the refrigerant in the pipe due to the start and stop of the unit repeatedly acts. In such a case, there is a risk of moisture in the air penetrating into the pressure sensor through the core wire due to the temperature difference, pressure difference, temperature expansion and contraction between the pressure sensor body and the external device side, which is called breathing action. In such a case, moisture in the air may penetrate to the other end surface side of the circuit board 1431, which may cause short circuits in the circuit board due to condensation, migration, and the like.

[0009] Therefore, an object of the present invention is to provide a pressure sensor that can be used with high reliability by realizing a structure that reduces the stress applied to the internal circuit board and ensures liquid-tightness with high precision. [Means for solving the problem]

[0010] One aspect of the invention for a pressure sensor that solves the above problems is a pressure sensor in which a sensor for detecting the pressure of the object to be measured is connected to a circuit board that is mounted inside a case, the sensor being installed in a pressure chamber so as to receive the pressure of the object to be measured, the circuit board being installed so as to be interposed between the sensor and an external device in an installation space that is formed liquid-tight by filling the case with a sealing material, the circuit board being conductively connected to a core wire of a coated connecting member that is pulled out to the outside and connected to the external device, and the core wire of the coated connecting member being covered with a coating up to just before the installation space. Effect of the Invention

[0011] Thus, according to one aspect of the present invention, the mounted components of the circuit board are positioned within the installation space, and are prevented from coming into contact with the sealing material, thereby preventing stress load from being applied to the mounted components of the circuit board. In addition, the covering connection member is covered with a covering up to the front of the installation space where the circuit board is installed, and the core wire is introduced into the installation space from within the sealing material, i.e., the covered end of the lead wire is present within the sealing material, so that moisture is prevented from entering the installation space from between the covering and the core wire, and liquid-tightness can be ensured with high accuracy. Therefore, a pressure sensor that can be used with high reliability can be provided. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a pressure sensor according to a first embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration thereof. [Diagram 2] FIG. 2 is a diagram showing a pressure sensor according to a second embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration thereof. [Diagram 3] FIG. 3 is a diagram showing a first alternative embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration thereof. [Figure 4] FIG. 4 is a diagram showing a second alternative embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration thereof. [Diagram 5]FIG. 5 is a diagram showing a third alternative embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration thereof. [Figure 6] FIG. 6 is a diagram showing a fourth alternative embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration thereof. [Figure 7] FIG. 7 is a diagram showing a fifth alternative embodiment of the present invention, and is a vertical sectional view showing a schematic overall configuration thereof. [Figure 8] FIG. 8 is a diagram showing the prior art of this embodiment, and is a vertical sectional view showing a schematic overall configuration thereof. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a diagram illustrating a pressure sensor according to a first embodiment of the present invention.

[0014] First Embodiment 1, the pressure sensor 100 is fabricated so that a pressure sensor unit 10 having a pressure sensor chip (sensor) 11 installed therein is attached to a refrigerant pipe in a unit to measure the pressure of the refrigerant in a refrigeration cycle, for example, and pressure information detected by the pressure sensor chip 11 is output to an external device A, which is a control device for controlling the refrigeration cycle. The pressure sensor 100 of this embodiment is constructed so that the pressure sensor unit 10 having a metallic waterproof case 20 formed in a cylindrical shape can be connected, for example, by a metallic joint member 30, to a pipe to be measured through which a fluid such as a gas or liquid whose pressure is to be detected is introduced.

[0015] Here, the waterproof case 20 is fixed by covering one end face of a thick cylindrical metal housing 12 that houses the sensor chip 11 of the pressure sensor unit 10 and welding it, and the peripheral portion of a disk-shaped metal cap 28 to which a joint member 30 is fixed is connected to the other end face of the housing 12 by welding. The joint member 30 is formed with a female thread 30s so that it can be screwed to a pipe or the like for which pressure is to be measured, and a fluid supplied from the pipe in the direction of arrow P is introduced into a pressure chamber PR, which is a space surrounded by the cap 28, the housing 12, and a diaphragm 32 described later, through a port 30a communicating with the female thread 30s. Here, the waterproof case 20, the housing 12, and the cap 28 are integrated with a desired joint strength by welding the outer peripheral portions from the outside by TIG welding, plasma welding, laser welding, or the like.

[0016] The housing 12 is arranged so that the support 13, on one end of which the pressure sensor chip 11 is installed, is located at the center of the inner cylinder, and hermetic glass 14 is formed by filling the space between the inner surface of the housing 12 and the outer surface of the support 13 to ensure a closed state while fixing the members that pass through the interior in a liquid-tight manner.

[0017] In this pressure sensor unit 10, a metal diaphragm 32 is bonded and fixed to the bottom end surface of the housing 12. The diaphragm 32 forms an airtight pressure chamber PR on the cap 28 side, while isolating the installation space of the pressure sensor chip 11 on the support 13 side in the housing 12 from the pressure chamber PR.

[0018] In this pressure sensor unit 10, the installation space for the pressure sensor chip 11, which is formed by the hermetic glass 14 and the diaphragm 32 within the inner tube of the housing 12, is filled with, for example, a predetermined amount of silicone oil (or a fluorine-based inert liquid, etc.) as a pressure transmission medium, so as to function as a liquid-sealed chamber LR.

[0019] As a result, the pressure sensor chip 11 functions as a pressure sensor that detects the pressure of the fluid to be detected, introduced into the pressure chamber PR from the piping connected to the joint member 30, as a pressure fluctuation of the pressure transmission medium in the liquid-sealed chamber LR via the diaphragm 32. That is, the pressure chamber PR in this embodiment is constructed in a structure including a liquid-sealed chamber LR, and is fabricated in a structure that enables the pressure sensor chip 11 to detect the pressure of the fluid to be measured introduced from the joint member 30. Note that the pressure chamber may not include a liquid-sealed chamber, and the pressure of the fluid to be measured may be directly applied to the sensor chip to be measured, and it goes without saying that the measurement target is not limited to liquid, but may be gas such as various gases or mist-like gas containing fine fluid particles.

[0020] Here, the pressure sensor chip 11 is installed so that it is supplied with power by electrically connecting lead pins (pin members) 40 connected to a circuit board 50 (described later) via bonding wires 11w from the external device A, and outputs a detection signal as pressure information. In addition, the liquid-sealed chamber LR between the hermetic glass 14 and the diaphragm 32 in the inner cylinder of the housing 12 is filled with a pressure transmission medium via an oil filling pipe 44. These lead pins 40 and the oil filling pipe 44 are aligned at equal intervals in a circle around the support 13, and are supported insulated from the housing 12 via an insulator such as the hermetic glass 14. One end of the oil filling pipe 44 is closed after filling with the pressure transmission medium.

[0021] Here, the diaphragm 32 is prevented from being damaged by external forces or sudden pressures applied to the pressure chamber PR by a diaphragm protective cover 34 having a plurality of communication holes 34a bonded and fixed to the lower end surface of the housing 12. Also, a concave frame 16 is fixed to one end side of the hermetic glass 14 and a lid-like shield plate 17 is attached to the frame 16, and the frame 16 contains a pressure transmission medium between the pressure sensor chip 11 side and the diaphragm 32 side through the communication holes 17a formed in the shield plate 17 and suppressing sudden pressure fluctuations.

[0022] The lead pins 40 include two power supply terminals, one output signal terminal, and five adjustment terminals used during assembly, and are electrically connected to the pressure sensor chip 11 via bonding wires 11w. These lead pins 40 are fixedly supported by the hermetic glass 14 so as to protrude from one end face side of the housing 12.

[0023] One end of a resin spacer 24 formed in a short, roughly cylindrical shape is fitted into one end surface of the housing 12 from one end opening side of the waterproof case 20, one end of the spacer 24 abuts against one end surface of the housing 12, and a cover member (space forming member) 25 is fixed to close the other end opening side of the spacer 24. With this structure, the pressure sensor unit 10 is constructed, which includes an installation space SR for a circuit board 50 to which the lead pins 40 and the lead wires 38 are connected. The waterproof case 20 of the pressure sensor unit 10 is filled with a sealant 26 such as a urethane resin, thereby waterproofing the installation space SR for the circuit board 50 and fixing it, and the circuit board 50 is soldered to the lead pins 40 and the core wires C of the lead wires 38 and positioned and supported. The circuit board 50 may be fixed so that a part of the outer peripheral end is supported by an adhesive or the like against the inner surface of the spacer 24.

[0024] Here, by arranging the circuit board 50 in the installation space SR formed by the housing 12, the spacer 24, and the cover member 25 inside the waterproof case 20, an air layer with low thermal conductivity can be formed around the circuit board 50, and it is possible to prevent temperature changes from around the pressure sensor or from the piping from being suddenly transmitted to the circuit board 50. Also, by arranging the circuit board 50 itself and the mounted components mounted on the circuit board 50 so that they do not come into contact with the sealing material 26, it is possible to prevent mechanical stress caused by the contraction and expansion of the sealing material 26 due to changes in the ambient temperature from acting on the connecting members, the mounted components, and in particular on their soldered portions.

[0025] Both ends of this lead pin 40 penetrate both sides of the hermetic glass 14 inside the inner tube of the housing 12, and one end on the liquid-sealed chamber LR side is conductively connected to the pressure sensor chip 11 via a bonding wire 11w, while the other end of the lead pin 40, which corresponds to the power supply terminal and output signal terminal, penetrates through multiple through holes (not shown) in the circuit board 50 in the direction toward the cover member 25 and is conductively connected by soldering or the like.

[0026] In addition, the lead wire 38 that is drawn out so as to be connectable to the external device A is soldered or the like to electrically connect the lead wire 38 to the housing 12 through a through hole 25h that penetrates the cover member 25, and then through a through hole (not shown) that penetrates the circuit board 50 at one point in the direction toward the housing 12. The lead wire 38 that is connected to the circuit board 50 is embedded (molded) in the sealing material 26 with the coating 38c around the core wire C peeled off up to the cover member 25 that forms the installation space SR, and the sealing material 26 is present between the core wire C and the coating 38c, that is, up to the coating end that is the boundary area, so that the sealing material 26 is surely sealed liquid-tightly. Here, the circuit board 50 is appropriately opened with through holes and the like so as to enable assembly work, and for example, an insertion hole (not shown) for the oil filling pipe 44 is also opened. It goes without saying that the connection of the lead pin 40 and the lead wire 38 may be made not only by molten metal such as solder, but also by applying, for example, an adhesive containing a conductive material. Furthermore, as described above, in addition to the conductive connection using soldering or a conductive adhesive, the conductive connection may be achieved by welding (for example, spot welding using a laser or the like), and there is no need to limit the welding method to a particular one.

[0027] Here, the circuit board 50 is arranged in series between the pressure sensor chip 11 and the external device A to function as a part of the circuit configuration, and in this embodiment, an input / output voltage conversion adjustment circuit is mounted thereon to adjust different input / output voltages between the pressure sensor chip 11 and the external device A, for example, to convert the input voltage DC12V or DC3.3V of the external device A to the operating voltage DC5V of the pressure sensor chip 11. This type of conversion adjustment circuit is not limited to this embodiment, but is any conversion adjustment circuit for dealing with various driving voltages and signal formats of pressure detection signals, such as a voltage output format of driving / output voltage different from this embodiment, a current output format such as a two-wire type / three-wire type, or a digital output format. Note that these conversion adjustment circuits are configured by mounting a plurality of electronic components (not shown).

[0028] Thus, in the pressure sensor 100 of this embodiment, the circuit board 50, which is connected in series between the sensor chip 11 and the external device A, is accommodated in the installation space SR in the case 20, which is filled with the sealing material 26 and sealed liquid-tightly. Therefore, in the pressure sensor 100, the circuit board 50 located in the installation space SR formed on one end face side of the housing 12 by the spacer 24 and the lid member 25 can prevent the mechanical load caused by the direct contact of the sealing material 26 made of a molten high-temperature resin during production and the thermal stress caused by the difference in the degree of expansion and contraction due to the difference in the linear expansion coefficient of the constituent materials in response to temperature changes during use from being applied as a stress load to the board itself and the mounted components.

[0029] Furthermore, in this pressure sensor 100, the coating 38c of the lead wire 38 connected to the circuit board 50 is peeled off just before the lid member 25 that forms the installation space SR, and the core wire C of the lead wire 38 penetrates the lid member 25 to be electrically connected. Therefore, even if the core wire C of the lead wire 38 is a twisted wire, the end of the coating 38c can be embedded in the sealant 26 outside the installation space SR, and even if there is moisture that is transmitted around the core wire C, it can be prevented from infiltrating into the circuit board 50. In this embodiment, the core wire C is inserted through the through hole 25h of the lid member 25, but an adhesive may be applied between the core wire C and the through hole 25h of the lid member 25. Since the core wire C is a twisted wire, a small gap may be generated inside. Therefore, by applying an adhesive to the through hole 25h to seal and fix the small gap, a double seal structure can be formed by the sealant 26 and the adhesive. This makes it possible to further prevent moisture in the air from passing through the minute space inside the core wire C of the lead wire 38 and entering the installation space SR.

[0030] As a result, the pressure sensor 100 can ensure high precision liquid-tightness of the installation space SR in which the circuit board 50, lead pins 40, etc. are present, and can be used with high reliability by suppressing the occurrence of short circuits and migration due to condensation.

[0031] <Second embodiment> 2 is a diagram illustrating a pressure sensor according to a second embodiment of the present invention. Since this embodiment is configured in substantially the same manner as the above-described embodiment, the same components are denoted by the same reference numerals, detailed description is omitted, and only the characteristic parts are described (the same applies to the other embodiments described below).

[0032] In FIG. 2, in the pressure sensor 100, instead of the spacer 24 of the above-described embodiment, a resin spacer 124 formed in a cylindrical shape with a bottom is fitted into one end opening side of the waterproof case 20 so that the bottom 124b abuts and is fixed against one end face side of the housing 12, and a cover member 25 is fixed to the other end opening side of the spacer 124, thereby constructing a pressure sensor unit 10 having an installation space SR for a circuit board 50 to which the lead pins 40 and lead wires 38 are connected.

[0033] Here, in this pressure sensor 100, a step 124a is formed on the inner surface of the cylindrical middle section of the spacer 124, and after assembling the spacer 124 in a state in which the peripheral end of the circuit board 50 is placed on the step 124a, the opposite opening of the housing 12 is covered with the lid member 25 and filled with the sealant 26, thereby making the installation space SR for the circuit board 50 a liquid-tight structure.

[0034] In the pressure sensor 100, instead of the core wire C of the lead wire 38 of the above-described embodiment, one end of a contact pin (external connection member) 126 that passes through the through hole 25h of the cover member 25 passes through a through hole of the circuit board 50 in a direction toward the housing 12 and is electrically connected by soldering or the like, and the core wire C protruding from the coated end of the lead wire 38 is electrically connected to the other end of the contact pin 126 by soldering or the like.

[0035] For this reason, the lead wire 38 drawn out so as to be connectable to the external device A is connected to the contact pin 126 with the coating 38c around the core wire C being stripped away up to the lid member 25 forming the installation space SR, and is embedded in the sealing material 26. The ends of the core wire C and the coating 38c are liquid-tightly sealed by the sealing material 26.

[0036] In this manner, in the pressure sensor 100 of this embodiment, the lead wire 38 is connected to the circuit board 50 via the contact pin 126 penetrating the cover member 25, and the core wire C from which the coating 38c of the lead wire 38 is stripped is conductively connected to the contact pin 126 just before the cover member 25 that forms the installation space SR. Therefore, this pressure sensor 100 can also obtain the same effects as the above-mentioned embodiment, and can be used with high reliability by ensuring the liquid-tightness of the installation space SR with high accuracy. Note that, in this embodiment, as in the first embodiment, an adhesive may be applied to the insertion portion of the contact pin 126 in the through hole 25h of the cover member 25. A minute gap may be generated in the through hole 25h for inserting the contact pin 126. Therefore, the minute gap can be sealed and fixed by applying an adhesive to the through hole 25h, so that a double seal structure can be formed by the sealant 26 and the adhesive. This makes it possible to further prevent moisture in the air from passing through the minute space between the contact pin 126 and the through hole 25h and entering the installation space SR.

[0037] <Other forms of the first type> As shown in FIG. 3, the pressure sensor 100 according to the first alternative aspect of the above-described embodiment includes, instead of the metallic waterproof case 20 in the above-described embodiment, a resin waterproof case 220 formed in a roughly cylindrical shape that extends not only outside the installation space SR but also from the entire outer circumferential surface of the housing 12 toward the coupling member 30 to a position beyond the cap 28.

[0038] In this pressure sensor 100, instead of ensuring liquid-tightness by welding the waterproof case 20 and cap 28 to the housing 12, the entire pressure sensor unit 10 is covered with a resin waterproof case 220 to ensure liquid-tightness, and in addition to the sealant 26 being filled on the outside of the cover member 25 on one end of the waterproof case 220, a sealant 226 is also filled on the outside of the cap 28 on the other end of the waterproof case 220 to make the space between it and the housing 12 liquid-tight.

[0039] <Second other form> As shown in FIG. 4, in the pressure sensor 100 of the second alternative aspect of the above-described embodiment, a generally cylindrical waterproof case 320 made of resin is attached instead of the waterproof case 220 in the above-described other aspect, and as in the first alternative aspect, sealing materials 26, 226 are filled on the outside of the cover members 25 and caps 28 on one and the other ends of the waterproof case 320 to ensure liquid-tightness.

[0040] In this pressure sensor 100, instead of the above-mentioned spacer 124, a resin spacer 324 formed in a cylindrical shape with a bottom, with one end opening omitted, is fixed to one end face of the housing 12 with its bottom 324b abutting at the position (height) of the step 124a, and a circuit board 50 to which the lead pins 40 and the lead wires 38 are connected is fixed to the one end opening side of the spacer 324.

[0041] The waterproof case 320 is formed so that a cover member 325 having substantially the same outer shape as the housing 12 can be attached thereto, and a small diameter region 320r having a reduced diameter is formed between a portion covering the entire outer circumferential surface of the housing 12 and a portion covering the outer circumferential end of the cover member 325. With this structure, the waterproof case 320 restricts the housing 12 and the cover member 325 from approaching each other at both ends of the small diameter region 320r, thereby ensuring a separation distance between them and securing an installation space SR for installing the circuit board 50. The contact pin 126 similarly penetrates a through hole 325h of the cover member 325 and is conductively connected to the circuit board 50.

[0042] In short, this waterproof case 320 forms an installation space SR in which a circuit board 50 can be installed by assembling the waterproof case 320 without using spacers 24, 124, 224, by abutting the outer peripheral end of the housing 12 against the step 320a on one end side of the small diameter region 320r and abutting the outer peripheral end of the cover member 325 against the step 320b on the other end side.

[0043] <Third other form> As shown in FIG. 5, in the pressure sensor 100 according to the third alternative aspect of the above embodiment, two resin waterproof cases 420A and 420B are attached instead of the waterproof case 320 in the above alternative aspect.

[0044] The waterproof case 420A is formed in a cap shape by integrally forming the lid member 325 at the position of the step 320a of the small diameter region 320r of the above-mentioned waterproof case 320, and is provided with the corresponding step 420a, small diameter region 420r, and lid-shaped portion 420c. The waterproof case 420B has an inner diameter that accommodates the small diameter region 420r of the waterproof case 420A, and is extended to the lead wire 38 side to ensure a space to be filled with the sealant 26.

[0045] In short, the waterproof cases 420A and 420B are constructed by forming an installation space SR in which the circuit board 50 can be installed simply by abutting the outer peripheral end of the housing 12 against the step 420a on one end side of the small diameter region 420r, without using the spacers 24, 124, 224 or the cover member 25, and by attaching the waterproof case 420B to the small diameter region 420r of the waterproof case 420A. The waterproof cases 420A and 420B are constructed by filling the opening side of the waterproof case 420A with the sealant 226 to liquid-tightly seal between the housing 12 and the cap 28, and filling the opening side of the waterproof case 420B with the sealant 26 and installing the covered ends of the lead wires 38 so as to be embedded in the sealant 26, thereby ensuring liquid-tightness.

[0046] Here, in this pressure sensor 100, similarly to the above-mentioned cover member 25, a through hole 420h penetrating a contact pin 126 which is connected to the circuit board 50 and conductively connected to the core wire C of the lead wire 38 is formed in the cover-shaped portion 420c of the waterproof case 420A, and the circuit board 50 is positioned and supported in the air by soldering and conductively connecting both the lead pin 40 and the contact pin 126 within the installation space SR formed within the waterproof case 420A.

[0047] <Fourth other form> 6, in the pressure sensor 100 according to the fourth alternative aspect of the above-described embodiment, instead of the lid member 25 etc. in the above-described aspect, in addition to the cylindrical spacer 324, a cylindrical resin spacer 524 with a bottom is fitted upside down in the form of a cap into the waterproof case 20 to form an installation space SR for installing a circuit board 50 between the spacer 524 and one end face side of the housing 12. That is, the spacer 524 is formed so that the outer peripheral wall portion 524s functions as the spacer 24 that prevents the sealant 26 from entering, and the bottom portion 524b functions as the lid-shaped portion of the lid member 25 to form and secure the installation space SR in which the circuit board 50 etc. can be installed.

[0048] A connector housing 533, in which a contact member 531 conductively connected to the circuit board 50 is located, is integrally formed on a bottom 524b of the spacer 524, and a male type connector 530 is formed by the contact member 531 and the connector housing 533. The contact member 531 is conductively connected to the circuit board 50 by passing through a through hole 524h in the bottom 524b of the spacer 524 that is integral with the connector housing 533, and the sealant 26 is filled on the opening side of one end of the waterproof case 20 on the outside of the spacer 524, as in the above embodiment, to ensure liquid tightness.

[0049] With this structure, the pressure sensor unit 10 is equipped with a male type connector 530, and is made capable of connecting an external device A to the circuit board 50 via the contact member 531 and the lead wire 38 by inserting a female type connector (not shown) connected to one end of the lead wire 38 into the connector housing 533.

[0050] That is, the pressure sensor unit 10 can be structured such that the core wire C of the lead wire 38 is not positioned in the installation space SR such as the circuit board 50, but the coating 38c of the lead wire 38 is stripped outside the installation space SR and connected to the female connector side that is connected to the male connector 530, so that moisture does not infiltrate into the installation space SR from the lead wire 38. In this embodiment, an adhesive may be applied to the contact member 531 and the insertion portion of the through hole 524h. The through hole 524h may have a small gap for the insertion of the contact member 531. Therefore, by applying an adhesive to the through hole 524h to seal and fix the small gap, a double seal structure can be formed by the sealant 26 and the adhesive. This can further prevent moisture in the air that has traveled along the core wire C of the lead wire 38 from infiltrating into the installation space SR.

[0051] <5th Alternative Form> 7, the pressure sensor 100 according to the fifth aspect of the above embodiment includes a resin spacer 624 that is formed with a smaller diameter than the bottomed cylindrical spacer 124 in the above embodiment and is fixed to one end surface side of the housing 12, and the pressure sensor unit 10 is constructed by covering and closing the opening side of the spacer 624 with a space cap 625, and is provided with an installation space SR in which a circuit board 50 is installed. This pressure sensor unit 10 is configured to ensure liquid-tightness around the installation space SR by filling a sealant 626 from the outer periphery of the housing 12 to the space cap 625 in a waterproof case 520 that is formed with a larger diameter than the outer periphery of the housing 12 and is extended to the vicinity of the closed end of the space cap 625 on the opposite side by fitting the cap 28 on the other end surface side.

[0052] The spacer 624 is constructed so that the terminal pieces 636a, 636b of both contact members 636 are inserted between the lead pin 40 penetrating the bottom portion 624b and the circuit board 50 in the installation space SR from the outer side surface of the side wall portion 624s, and the inserted portion is fixed by a terminal fixing adhesive. Thereafter, the lead pin 40 and the terminal piece 636a, and the circuit board 50 and the terminal piece 636b are electrically connected to each other, so that the pressure sensor chip 11 can be connected to the circuit board 50. Similarly, the spacer 624 is constructed so that the terminal piece 637a of one contact member 637 is inserted from the outer side surface of the side wall portion 624s on the opposite side of both contact members 636, and the inserted portion is fixed by a terminal fixing adhesive. Thereafter, the circuit board 50 and the terminal piece 637a are electrically connected, and the core wire C, from which the coating 38c has been stripped so as to protrude from the coated end of the lead wire 38, is soldered to the flat portion 637f located on the outer surface of the side wall portion 624s of the contact member 637 for electrically connecting. In this manner, the contact members 636 and 637 are fixed to the spacer 624 with an adhesive, thereby preventing each terminal piece from falling off the spacer and preventing the insertion position from shifting. After the electrically connecting, the sealant 626 is filled inside the waterproof cover 20 so that the connection portion and the coated end of the lead wire 38 are sealed. With this structure, in the pressure sensor chip 11, the lead pin 40 and the circuit board 50 are electrically connected in series to the lead wire 38 via the contact members 636 and 637 in this other embodiment as well.

[0053] That is, in this other embodiment, the lead wire 38 that is drawn out so as to be connectable to the external device A is connected to one contact member 637 outside the installation space SR, and the core wire C from which the coating 38c has been peeled and the coated end of the lead wire 38 are embedded liquid-tightly in the sealing material 626. Furthermore, the core wire C is electrically connected to the lead pin 40 in the installation space SR via both contact members 636 that are configured to once bypass the sealing material 626 from the spacer 624. As a result, the pressure sensor 100 can ensure high accuracy of liquid-tightness of the installation space SR in which the circuit board 50, the lead pin 40, etc. are present, and can be used with high reliability by suppressing the occurrence of short circuits and migration due to condensation. In addition, the insertion portions of the terminal pieces 636a, 636b, and 637a of the side wall portion 624s may have minute gaps that allow the terminal pieces to be inserted. The amount of adhesive applied to fix the contact members 636 and 637 in this embodiment may be an amount that completely blocks the gaps in the insertion portions. In this way, minute gaps can be sealed and fixed by applying adhesive to the contact members 636, 637, so that a double seal structure can be achieved by the sealant 626 and the adhesive, which can further prevent moisture in the air from penetrating into the installation space SR.

[0054] The scope of the present invention is not limited to the exemplary embodiments shown and described, but includes all embodiments that achieve equivalent effects to the object of the present invention. Moreover, the scope of the present invention is not limited to the combination of inventive features specified in each claim, but may be defined by any desired combination of each and every particular feature disclosed. [Explanation of symbols]

[0055] 10...Pressure sensor unit 11...Pressure sensor chip 20, 220, 320, 420A, 420B, 520...Waterproof case 24, 124, 324, 624...Spacers 25, 325...Cover parts 26, 226, 626...Sealing material 30...Joint member 38...Lead wire 38c……Covering 40...Lead pin 44...Oil filling pipe 50...Circuit board 100...Pressure sensor 126……Contact pin 524...Spacer 530……Connector 531: Contact member 625...Space Cap 636...Both contact members 637... Single contact member A……External device C...Core wire SR……Installation space

Claims

1. A pressure sensor in which a sensor for detecting a pressure to be measured is connected to a circuit board that is installed inside a case, the sensor is installed in a pressure chamber to receive a pressure to be measured, and the circuit board is installed between the sensor and an external device in an installation space formed liquid-tight by filling the case with a sealant, The circuit board is electrically connected to a core wire of a coated connecting member that is pulled out to the outside and connected to the external device, and the core wire of the coated connecting member is covered with a coating up to the installation space.

2. 2. The pressure sensor according to claim 1, wherein the conductive core wire of the covering connection member penetrates a space forming member that defines the installation space and is conductively connected to the circuit board.

3. 2. The pressure sensor according to claim 1, wherein the conductive core wire of the covering connection member is conductively connected to the circuit board via an external connection member that penetrates a space forming member that forms the installation space.

4. 2. The pressure sensor according to claim 1, wherein the covered connecting member is formed of an electric wire having a core wire made of a stranded wire covered with a covering.

5. 4. The pressure sensor according to claim 3, wherein the external connection member is a component part of a connector that can penetrate a space forming member that forms the installation space and be connected to the covering connection member.

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