pressure sensor

Abstract

To provide a pressure sensor that reduces stress applied to a circuit board mounted therein and achieves a structure ensuring insulating properties, and can thereby measure pressure with high quality.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 pressure sensor comprises a space forming member constituted of a spacer 24 forming an installation space, a lid member 25, and one end face sides of a housing 12, a pillar 13, and hermetic glass 14, and the spacer also constitutes an insulation improvement member that improves insulation resistance to the circuit board. A mounting component 50J of the circuit board is located inside 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 Art

[0002] Various sensors for detecting pressure, temperature, etc. are used to be fixed near the measurement object and send the detection signal to a measuring device or the like, and are frequently used in a form built-in or externally attached to the measuring device.

[0003] This type of various sensors is incorporated into a sensor unit so that it can be installed in a place exposed to the same environment as the measurement object, and for example, when it is necessary to change the electrical characteristics input and output to the sensor chip, a circuit board may be installed inside (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the pressure sensor described in Patent Document 1, as shown in FIG. 11, a circuit board 1431 connected to a sensor chip 1121 in a housing 1124 is housed in a case 1135, and a sealing material such as a resin material 1136 is filled in the case 1135 to be liquid-tightly sealed.

[0006] In such a structure, because there are differences in the coefficients of linear expansion of the constituent materials such as the circuit board 1431, the case 1135, and the sealing material 1136, when a temperature difference occurs inside or outside the object being measured, stress corresponding to that temperature difference may occur. This stress may become a load on the circuit board 1431 itself or the components mounted on the circuit board 1431. Furthermore, since various electrical and electronic components are mounted on the circuit board 1431 in such a pressure sensor, it is necessary to ensure insulation around the circuit board 1431.

[0007] Therefore, the present invention aims to provide a pressure sensor that can perform high-quality pressure measurement by realizing a structure that reduces the stress applied to the internal circuit board while ensuring insulation. [Means for solving the problem]

[0008] 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 a target to be measured is connected to a circuit board housed in a case, wherein the sensor is installed in a pressure chamber to receive the pressure of the target to be measured, the circuit board is installed in an installation space formed liquid-tight by filling the case with a sealing material, and the invention comprises a space-forming member that forms the installation space and an insulation-improving member that improves the insulation resistance between the space-forming member and the circuit board, wherein the mounted components of the circuit board are located within the installation space. [Effects of the Invention]

[0009] Thus, according to one aspect of the present invention, the mounted components of the circuit board are located within the installation space, preventing contact with the sealing material and thus preventing stress loads from being applied to the mounted components of the circuit board. Furthermore, the circuit board within the installation space has improved insulation resistance, and the mounted components are mounted on it. Therefore, a pressure sensor that can be used with high reliability can be provided. [Brief explanation of the drawing]

[0010] [Figure 1]Figure 1 is a diagram showing a pressure sensor according to a first embodiment of the present invention, and is a longitudinal cross-sectional view showing its schematic overall configuration. [Figure 2] Figure 2 is a diagram showing a pressure sensor according to a second embodiment of the present invention, and is a longitudinal cross-sectional view showing its schematic overall configuration. [Figure 3] Figure 3 is a diagram showing a pressure sensor according to a third embodiment of the present invention, and is a longitudinal cross-sectional view showing its schematic overall configuration. [Figure 4] Figure 4 is a diagram showing a pressure sensor according to a fourth embodiment of the present invention, and is a longitudinal cross-sectional view showing its schematic overall configuration. [Figure 5] Figure 5 is a diagram showing a pressure sensor according to a fifth embodiment of the present invention, and is a longitudinal cross-sectional view showing its schematic overall configuration. [Figure 6] Figure 6 is a diagram showing a pressure sensor according to the sixth embodiment of the present invention, and is a longitudinal cross-sectional view showing its schematic overall configuration. [Figure 7] Figure 7 is a diagram showing a pressure sensor according to the seventh embodiment of the present invention, and is a longitudinal cross-sectional view showing its schematic overall configuration. [Figure 8] Figure 8 is a diagram showing another first aspect of this embodiment, and is a longitudinal cross-sectional view showing its schematic overall configuration. [Figure 9] Figure 9 is a diagram showing a second other aspect of this embodiment, and is a longitudinal cross-sectional view showing its schematic overall configuration. [Figure 10] Figure 10 is a diagram showing a third other aspect of this embodiment, and is a longitudinal cross-sectional view showing its schematic overall configuration. [Figure 11] Figure 11 is a diagram showing the prior art of this embodiment, and is a longitudinal cross-sectional view showing its general overall configuration. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is a diagram illustrating a pressure sensor according to the first embodiment of the present invention.

[0012] <First Embodiment> In Figure 1, the pressure sensor 100 is constructed such that a pressure sensor unit 10, in which a pressure sensor chip (sensor) 11 is installed, is attached to the refrigerant piping in the unit, for example, to measure the pressure of the refrigerant in a refrigeration cycle, and the pressure information detected by the pressure sensor chip 11 is output to an external device A, which is a control device that controls the refrigeration cycle. The pressure sensor 100 in this embodiment is constructed so that the pressure sensor unit 10, which has a cylindrical metal waterproof case 20, can be connected, for example, to the piping to be measured through which a fluid such as a gas or liquid whose pressure is to be detected is led, using a metal joint member 30.

[0013] Here, the waterproof case 20 is fixed by welding or the like to one end face of a thick cylindrical metal housing 12 that houses the sensor chip 11 of the pressure sensor unit 10, and the peripheral edge of a disc-shaped metal cap 28 to which the joint member 30 is fixed is welded or the like to the other end face of the housing 12. The joint member 30 has a female thread 30s formed so that it can be screwed into a pipe or the like to be pressure measured, and through a port 30a communicating with the female thread 30s, the fluid supplied from the pipe in the direction of arrow P is introduced into the pressure chamber PR, which is the space surrounded by the cap 28, the housing 12 and the diaphragm 32 described later. Here, the waterproof case 20, the housing 12 and the cap 28 are integrated with a desired joint strength by welding the outer peripheral edges from the outside using TIG welding, plasma welding, laser welding, etc.

[0014] The housing 12 is positioned such that a support column 13, on which a pressure sensor chip 11 is installed at one end, is located in the center of the inner cylinder. A hermetic glass 14 is formed between the inner surface of the housing 12 and the outer surface of the support column 13, ensuring a sealed state while liquid-tightly fixing a member that penetrates the interior.

[0015] In this pressure sensor unit 10, a metal diaphragm 32 is joined and fixed to the lower end surface of the housing 12. The diaphragm 32 forms an airtight pressure chamber PR on the cap 28 side and isolates the installation space of the pressure sensor chip 11 on the support column 13 side in the housing 12 from the pressure chamber PR.

[0016] And in this pressure sensor unit 10, for example, a predetermined amount of silicone oil (or a fluorine-based inert liquid etc.) as a pressure transmission medium is filled into the installation space of the pressure sensor chip 11 formed by the hermetic glass 14 and the diaphragm 32 in the inner cylinder of the housing 12 so as to function as a liquid-sealed chamber LR.

[0017] Thereby, 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 pipe to which the joint member 30 is connected 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 of the present embodiment is constructed in a structure including the liquid-sealed chamber LR, and is fabricated in a structure that enables the pressure sensor chip 11 to detect the fluid pressure of the measurement object introduced from the joint member 30. Note that as the pressure chamber, it may be configured to directly load the fluid pressure of the measurement object on the sensor chip without including the liquid-sealed chamber, and needless to say, the measurement object is not limited to a liquid, and may be a gas such as various gases or a mist-like gas containing fine fluid particles.

[0018] Here, the pressure sensor chip 11 is powered by electrically connecting lead pins (sensor connection pin members) 40, which are connected to each of the multiple lead wires (external connection members) 38 from the external device A via a circuit board 50 (described later), and bonding wires 11w, and is installed to output a detection signal as pressure information. In addition, a pressure transmission medium is filled into the liquid-sealed chamber LR between the hermetic glass 14 and the diaphragm 32 inside the inner cylinder of the housing 12 via an oil-filling pipe 44. These lead pins 40 and oil-filling pipe 44 are aligned at equal intervals in a circular shape around the support column 13 and are supported insulated from the housing 12 via an insulator such as the hermetic glass 14. Note that one end of the oil-filling pipe 44 is closed after the pressure transmission medium has been filled.

[0019] Here, the diaphragm 32 is protected from damage by external forces or sudden pressure changes into the pressure chamber PR by a diaphragm protective cover 34 having multiple communication holes 34a that is joined and fixed to the lower end surface of the housing 12. In addition, a concave frame 16 is fixed to one end of the hermetic glass 14, and a lid-shaped shield plate 17 is attached to it. The frame 16 contains a pressure transmission medium that can flow freely between the pressure sensor tip 11 side and the diaphragm 32 side through communication holes 17a formed in the shield plate 17 to suppress sudden pressure fluctuations.

[0020] The lead pins 40 are electrically connected to the pressure sensor chip 11 via bonding wires 11w, with two power supply terminals, one output signal terminal, and five adjustment terminals used during assembly arranged in a row. These lead pins 40 are fixedly supported by the hermetic glass 14 so as to protrude from one end face of the housing 12.

[0021] On one end face of the housing 12, a short, roughly cylindrical resin spacer 24 is fitted into the waterproof case 20 from the opening side of the one end and abuts as a side wall of the space-forming member, while a lid member (closing member of the space-forming member) 25 is fixed to the opening side of the other end, so that this one end face of the housing 12 also functions as a closing member of the space-forming member. With this structure, a pressure sensor unit 10 is constructed that has an installation space SR for a circuit board 50 to which lead pins 40 and lead wires 38 are connected. The waterproof case 20 of the pressure sensor unit 10 is filled with a sealing material 26 such as urethane resin, so that the installation space SR for the circuit board 50 is waterproofed and fixed, and the circuit board 50 is positioned and supported by being soldered to the lead pins 40 and the core wires C of the lead wires 38.

[0022] In this structure, the circuit board 50 is supported vertically by soldered lead wires 38 and lead pins 40 and held in the intermediate hollow space SR. Therefore, when stress occurs, these lead wires 38 and lead pins 40 undergo slight deformation, preventing the stress itself from being applied. The circuit board 50 may also be further secured to the inner surface of the spacer 24 with adhesive or the like, with a portion of its outer edge being attached.

[0023] Here, by placing the circuit board 50 in the installation space SR formed by the housing 12, spacer 24, and lid member 25 within the waterproof case 20, a layer of air with low thermal conductivity can be formed around the circuit board 50, preventing temperature changes from the pressure sensor and piping from being rapidly transmitted to the circuit board 50. Furthermore, by positioning the circuit board 50 itself and the mounted components 50J mounted on the circuit board 50 so that they do not come into contact with the sealing material 26, mechanical stress caused by the contraction and expansion of the sealing material 26 due to ambient temperature changes can be prevented from acting on the connecting members, mounted components 50J, and especially their soldered parts.

[0024] The lead pins 40 have both ends that penetrate both sides of the hermetic glass 14 inside the inner cylinder of the housing 12. One end, which is on the liquid-sealing chamber LR side, is electrically connected to the pressure sensor chip 11 via a bonding wire 11w. The other end of the lead pins 40, which corresponds to the power supply terminal and the output signal terminal, is electrically connected by soldering or the like through multiple through holes (not shown) in the circuit board 50 in the direction toward the lid member 25.

[0025] Furthermore, the lead wire 38, which is extended to connect to external device A, passes through a through-hole 25h that penetrates the cover member 25, and then the core wire C passes through another through-hole (not shown) in one place on the circuit board 50 in the direction toward the housing 12, and is soldered or otherwise connected for electrical conductivity. Here, the circuit board 50 has through-holes and other openings as appropriate to allow for assembly work, and for example, an insertion hole (not shown) for the oil filling pipe 44 is also opened. Needless to say, the connection of the lead pin 40 and lead wire 38 may be made not only with molten metal such as solder, but also by applying, for example, an adhesive containing a conductive material. In addition to the above-mentioned electrical connections by soldering or conductive adhesive, electrical connections may also be made by welding (for example, spot welding with a laser, etc.), and there is no particular need to limit the means of welding.

[0026] Here, the circuit board 50 is placed in an installation space SR, which is formed by the housing 12, support columns 13, hermetic glass 14, spacers 24, and lid member 25 within the waterproof case 20, forming a space-forming member. The circuit board 50 is liquid-tightly housed in the installation space SR, which is formed by electrically conductive lead pins 40 and spacers 24 of a desired size that ensure a sufficient distance from the housing 12 and the waterproof case 20, which is at the same potential as the housing 12. In other words, since the installation space SR is an air atmosphere, it is difficult to maintain insulation with reliability and low cost compared to when it is embedded (molded) with a sealing material 26, but the spacers 24 also function as insulation-enhancing members that improve the insulation resistance of the circuit board 50 by ensuring a sufficient distance from the housing 12 and the waterproof case 20.

[0027] The circuit board 50 is interposed in series between the pressure sensor chip 11 and the external device A and functions as part of the circuit configuration. In this embodiment, it is equipped with an input / output voltage conversion and adjustment circuit that adjusts the different input and output voltages of the pressure sensor chip 11 and the external device A, for example, by converting the input voltage of the external device A, such as DC12V or DC3.3V, to the operating voltage of the pressure sensor chip 11, DC5V. This type of conversion and adjustment circuit is not limited to this embodiment, and is an arbitrary conversion and adjustment circuit that can accommodate various drive voltages and pressure detection signal signal methods, such as voltage output formats for drive and output voltages different from this embodiment, current output formats such as 2-wire / 3-wire, or digital output formats. These conversion and adjustment circuits are composed of multiple electronic components that are not shown in the figures.

[0028] Thus, in the pressure sensor 100 of this embodiment, the circuit board 50, which is interposed in series between the sensor chip 11 and the external device A, is housed in an installation space SR within a case 20 that is filled with a sealing material 26 to create a liquid-tight seal. Therefore, in the pressure sensor 100, the circuit board 50, which is 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 be prevented from being subjected to mechanical loads from direct contact with the high-temperature resin sealing material 26 that melts during manufacturing, and from thermal stresses caused by differences in the degree of expansion and contraction due to differences in the linear expansion coefficients of the constituent materials in response to temperature changes during use, etc., which can be prevented from being applied as stress loads to the board itself and the mounted components 50J.

[0029] Furthermore, with this pressure sensor 100, the spacer 24 can be used to ensure sufficient distance between the housing 12 and the waterproof case 20 in the installation space SR where the circuit board 50 is installed, thereby improving the insulation resistance of the mounted components 50J on the circuit board 50.

[0030] As a result, the pressure sensor 100 can measure pressure with high quality while ensuring the insulation of the circuit board 50.

[0031] <Second Embodiment> Next, Figure 2 illustrates a pressure sensor according to a second embodiment of the present invention. Here, since this embodiment is configured substantially the same as the embodiment described above, the same reference numerals are used for similar components, and detailed explanations are omitted, with the characteristic parts being described instead (the same applies to other embodiments described below).

[0032] In Figure 2, the pressure sensor 100 has a cylindrical resin spacer 124 with a bottom, which is fitted into the waterproof case 20 from the opening at one end, with its bottom portion 124b abutting against one end face of the housing 12. A cover member 25 is fixed to the opening at the other end of the spacer 124, constructing a pressure sensor unit 10 that has a space SR for installing a circuit board 50 to which lead pins 40 and lead wires 38 are connected. The spacer 124 is formed in a disc shape with an inner circumferential end surface 124i that leaves an opening for the lead pins 40 to pass through the hermetic glass 14, and has a bottom portion 124b of plate material that can abut against one end face of the housing 12.

[0033] In this pressure sensor 100, a step 124a is formed on the inner surface of the middle section inside the cylinder of the spacer 124. After assembling the spacer 124 with the peripheral edge of the circuit board 50 placed on the step 124a, the opposite opening of the housing 12 is covered with a lid member 25 and filled with a sealing material 26, thereby creating a liquid-tight structure for the installation space SR of the circuit board 50.

[0034] In this pressure sensor 100, the spacer 124, along with the housing 12, support column 13, hermetic glass 14, and lid member 25, forms a space-forming member within the waterproof case 20 to create an installation space SR where the circuit board 50 is placed. The side wall portion 124s and step 124a of the spacer 124 also function as an insulation-enhancing member that ensures sufficient distance between the circuit board 50 and the housing 12 and waterproof case 20, thereby improving the insulation resistance of the circuit board 50.

[0035] Thus, even in the pressure sensor 100 of this embodiment, the spacer 124 can be used to ensure a sufficient distance between the housing 12 and the waterproof case 20 in the installation space SR where the circuit board 50 is installed, thereby improving the insulation resistance of the mounted components 50J and obtaining the same effects as in the above-described embodiment.

[0036] <Third Embodiment> Next, Figure 3 illustrates a pressure sensor according to a third embodiment of the present invention. In Figure 3, the pressure sensor 100 is configured substantially the same as in the second embodiment described above, with the addition of a spacer 124. In this pressure sensor 100, instead of the core wire C of the lead wire 38, one end of a contact pin (external connection pin member) 126, which passes through the through hole 25h of the cover member 25, is soldered or otherwise connected to the through hole of the circuit board 50 in the direction toward the housing 12, and the core wire C of the lead wire 38 is soldered or otherwise connected to the other end of the contact pin 126.

[0037] Therefore, the lead wire 38, which is extended to connect to the external device A, is connected to the contact pin 126 and embedded in the sealing material 26 with the insulation 38c around the core wire C stripped up to the front of the cover member 25 that forms the installation space SR, and the boundary region between the core wire C and the insulation 38c, that is, the end of the insulation 38c of the lead wire 38, is sealed liquid-tightly by the sealing material 26.

[0038] Thus, in the pressure sensor 100 of this embodiment, the insulation 38c of the lead wire 38 connected to the circuit board 50 is peeled off in front of the cover member 25 that forms the installation space SR, and the core wire C of the lead wire 38 penetrates the cover member 25 and is electrically connected. Therefore, even if the core wire C of the lead wire 38 is a stranded wire, the space between it and the insulation 38c can be embedded in the sealing material 26 outside the installation space SR, and even if moisture is present around the core wire C, it can be prevented from entering the circuit board 50.

[0039] As a result, the same effects as those of the above-described embodiment can be obtained with the pressure sensor 100, ensuring the insulation of the circuit board 50 and enabling high-quality pressure measurement.

[0040] <Fourth Embodiment> Next, Figure 4 is a diagram illustrating a pressure sensor according to a fourth embodiment of the present invention. In Figure 4, the pressure sensor 100 is provided with the spacer 24 of the above embodiment in addition to the following: The housing 12 is equipped with a plate 224 (not limited to a plate, but may be a flexible sheet material) which is a closing member made of a plate material and is formed in a disc shape having an inner circumferential end surface 224i so as to leave open the passage for the lead pin 40 of the hermetic glass 14, and is able to abut against one end surface of the housing 12.

[0041] With this structure, in the pressure sensor 100, the plate 224 is positioned between the housing 12 and the circuit board 50 facing the housing 12 within the installation space SR, forming a space-forming member. It can also function as an insulation-enhancing member that improves the insulation resistance between the housing 12 and the circuit board 50, thereby ensuring the insulation of the circuit board 50.

[0042] Thus, in this embodiment, the pressure sensor 100 can obtain the same effects as the above-described embodiment, and in addition, the insulation resistance between the housing 12 and the installation space SR can be improved by the plate 224, and the insulation of the mounted components 50J on the circuit board 50 can be ensured with greater reliability and quality.

[0043] <Fifth Embodiment> Next, Figure 5 is a diagram illustrating a pressure sensor according to a fifth embodiment of the present invention. In Figure 5, the pressure sensor 100 is equipped with a resin spacer 324 formed in the shape of a bottomed cylindrical object, which is integrally molded with the spacer 24 and cover member 25 of the above embodiment, instead of the spacer 24 and cover member 25 of the above embodiment. By reversing the top and bottom of the spacer 324 and fixing it with the opening side in contact with the housing 12, it forms a space-forming member that, together with the plate 224 of the above embodiment, forms the installation space SR for the circuit board 50.

[0044] With this structure, in this pressure sensor 100, the plate 224 and the bottom 324r of the spacer 324 face each other on both sides of the circuit board 50, and the side wall portion 324s of the spacer 324 can also function as an insulating member that improves the insulating resistance of the circuit board 50 by ensuring the separation distance between the plate 224 and the bottom 324r of the spacer 324.

[0045] Thus, in addition to obtaining the same effects and advantages as the above-described embodiment, the pressure sensor 100 of this embodiment uses a bottomed cylindrical spacer 324 in which the spacer 24 and the lid member 25 are integrally molded, thereby reducing the number of parts and labor, and thus lowering costs.

[0046] <Sixth Embodiment> Next, Figure 6 illustrates a pressure sensor according to a sixth embodiment of the present invention. In Figure 6, the pressure sensor 100 includes the spacer 324 and contact pin 126 described in the above embodiment. The contact pin 126 passes through the through hole 324h in the bottom 324r of the spacer 324 and is electrically connected to the core wire C of the lead wire 38 together with the circuit board 50.

[0047] Here, in this pressure sensor 100, the circuit board 50 is soldered to the contact pin 126 and lead pin 40, which are electrically connected to the core wire C of the lead wire 38, and is positioned and supported in the hollow space SR within the installation space. However, a part of the outer edge may be further fixed to the inner surface of the spacer 124 with adhesive or the like.

[0048] Thus, the pressure sensor 100 of this embodiment can also obtain the same effects and advantages as those of the embodiment described above.

[0049] <Seventh Embodiment> Next, Figure 7 illustrates a pressure sensor according to a seventh embodiment of the present invention. In Figure 7, the pressure sensor 100 forms an installation space SR for the circuit board 50 by fixing the opening side of the side wall portion 324s of the spacer 324 to the housing 12 without using the plate 224 of the above embodiment, and the core wire C of the lead wire 38 is electrically connected to the circuit board 50 without using the contact pin 126 of the above embodiment.

[0050] Furthermore, in this pressure sensor 100, a resin material is applied to cover the entire circuit board 50, including the connection points between the lead pins 40 and the core wire C of the lead wires 38 on both sides, and the mounted components 50J, and is coated with an insulating coating material (insulation-enhancing member) 424. In addition, a resin material is applied to cover the entire end face of the housing 12 and the support column 13, including the through-protruding portion of the lead pins 40 on the hermetic glass 14 side, and is coated with an insulating coating material (insulation-enhancing member) 426.

[0051] With this structure, in this pressure sensor 100, both sides of the circuit board 50 are covered with insulating coating material 424, thereby improving insulation, and the housing 12 side is also covered with insulating coating material 426, thereby improving insulation.

[0052] Thus, in the pressure sensor 100 of this embodiment, the circuit board 50 itself and the housing 12 are covered with insulating coating materials 424 and 426, ensuring insulation at the connection points with the lead pins 40 and the core wire C of the lead wires 38, thereby enabling highly reliable and high-quality pressure measurement.

[0053] <Another form of the first> In another embodiment of the first pressure sensor 100 described above, as shown in Figure 8, a resin material is applied to the exposed portion from the cylindrical shape within the inner circumferential end face 124i of the bottom 124b of the spacer 124 in the second embodiment described above, up to the gap between the bottom 124b and the hermetic glass 14, and then coated with an insulating coating material (insulation improving member) 524. As a result, the insulation resistance of the through-protruding portion of the lead pin 40 on the hermetic glass 14 side is improved, and insulation between the lead pin 40 and the housing 12, and between the housing 12 and the circuit board 50 is ensured.

[0054] In the second other embodiment of the above-described embodiment, as shown in Figure 9, a generally cylindrical metal waterproof case 620 is attached in place of the waterproof case 20 in the above-described embodiment, and a sealing material 26 is filled on the outside of the lid member 625, which will be described later, on the open end side of the waterproof case 620 to ensure liquid tightness.

[0055] Furthermore, in the pressure sensor 100, instead of the spacer 124 described above, a resin spacer 624 is fixed to the housing 12 with its bottom portion 624b in contact with one end face, forming a short cylindrical shape with a closed side wall, by omitting the opening on one end side at the position (height) of the step 124a. A circuit board 50 to which lead pins 40 and lead wires 38 are connected is fixed to the other end open portion 624a of the spacer 624.

[0056] Furthermore, the waterproof case 620 has locking portions 620t formed on the waterproof case, which are inwardly convex dimples or ribs, so that a desired space can be formed above the circuit board 50. The lid member 625, which has an outer diameter slightly smaller than that of the housing 12, is supported by engaging with the locking portions 620t. This ensures that the installation space SR for installing the circuit board 50 is secured without relying on the spacer 124.

[0057] As a third other embodiment of the above-described embodiment, the pressure sensor 100, as shown in Figure 10, is equipped with a housing 712 that is formed in a generally bottomed cylindrical shape by integrally forming a cylindrical side wall portion 712s similar to the spacer 24 on the outer circumference of a cylindrical base portion 712b having the same wall thickness as the housing 12, without using the spacer 24 or the like in the above-described embodiment. In this housing 712, as in the above-described embodiment, hermetic glass 14 is integrally formed inside the base portion 712b together with the support column 13, and an installation space SR for accommodating the circuit board 50 on which the mounted components 50J are mounted is formed by covering and fixing a lid member 725 so as to close the opening end of the side wall portion 712s.

[0058] In this pressure sensor 100, instead of the spacer 124 described above, a resin spacer 724 is formed in the shape of a cylindrical shape with a short side wall and a closed bottom, with one end opening omitted at the position (height) of the step 124a. This spacer is fixed to the base portion 712b of the housing 712 with its bottom portion 724b in contact with one end face. A circuit board 50 to which lead pins 40 and lead wires 38 are connected is positioned and fixed in the middle section of the installation space SR, on the other end opening of the spacer 724.

[0059] Furthermore, the pressure sensor 100 includes a waterproof case 720 that is formed in a generally cylindrical shape and encloses the entire outer surface of the lid member 725 along with the lateral outer surface of the housing 712 in the pressure sensor unit 10. The waterproof case 720 has one end opening 720a fixed to the peripheral edge of the cap 28 to which the joint member 30 is fixed, and the other end opening is filled with a sealing material 726 to create a liquid-tight seal up to the outer surface of the housing 712.

[0060] The scope of the present invention is not limited to the illustrative and described exemplary embodiments, but also includes all embodiments that produce effects equivalent to those aimed at by the invention. Furthermore, the scope of the invention is not limited to the combination of features of the invention specified by each claim, but can be defined by any desired combination of each of the disclosed specific features. [Explanation of symbols]

[0061] 10... Pressure sensor unit 11... Pressure sensor chip 12,712... Housing 20, 620, 720... Waterproof cases 24, 124, 324, 524, 624, 724... Spacers 25, 325, 625, 725... Lid parts 26, 226, 626, 726... sealing material 30... Joint member 38... Lead wire 40... Lead pin 50... Circuit board 50J... Mounted component 100... Pressure sensor 126... Contact pin 224... Plate 424, 426, 524... Insulating coating materials 620t……locking part A……External device C... Core wire SR……Installation space

Claims

1. A pressure sensor that detects the pressure of the object to be measured is connected to a circuit board housed inside a case, The sensor is installed in a pressure chamber to receive the pressure of the object to be measured, and the circuit board is installed in an installation space formed within the case. The system comprises a space-forming member that forms the aforementioned installation space, and an insulation-enhancing member that improves the insulation resistance between the space-forming member and the circuit board, The aforementioned installation space is formed to be liquid-tight by filling the outside of the space-forming member and the insulation-enhancing member installed inside the case with a sealing material. A pressure sensor characterized in that the components mounted on the circuit board are located within the installation space.

2. The pressure sensor according to claim 1, characterized in that the insulation-improving member is composed of a part of the space-forming member, and the space-forming member and the circuit board are separated by a desired distance to improve insulation resistance.

3. The pressure sensor according to claim 1, characterized in that the insulation-enhancing member is composed of at least one of a plate material, a sheet material, or a coating material made of an insulating material disposed between the space-forming member and the circuit board to improve insulation resistance.

4. The aforementioned installation space is formed by a space-forming member which comprises a side wall portion that forms a cylindrical shape capable of housing the circuit board, and a pair of closing members located at both ends of the cylindrical shape that close the opening. The side wall portion functions as a spacer to improve insulation resistance by setting a desired separation distance between the pair of closing members and the circuit board. The pressure sensor according to claim 1, characterized in that the side wall portion and the pair of closing members constitute the space forming member and the insulation improving member.

5. The side wall portion and one of the closing members are integrally formed to create a bottomed cylindrical shape, and the other closing member functions as a lid member of the cylindrical shape. The pressure sensor according to claim 4, characterized in that the side wall portion supports at least a portion of the peripheral end of the circuit board.

6. The circuit board is installed so as to be interposed between the sensor and the external device. The sensor is electrically connected to the circuit board via a sensor connection pin member that penetrates the space forming member. The pressure sensor according to claim 1, characterized in that the external connection member, which is drawn out to the outside and connected to the external device, is electrically connected to the circuit board via an external connection pin member that penetrates the space forming member.

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