Loop device

Abstract

This circuit device provides a long lifespan and high-precision signal processing capabilities, even when used in harsh environments such as those involving internal combustion engines. [Solution] The circuit device 30 comprises elastic members 1a and 1b that contact the circuit board 3, the electronic components 11, and the housing 13, and dissipate heat from the electronic components 11 to the housing 13. The elastic members 1a and 1b may have surfaces that conform to the surface shapes of the circuit board 3 and the electronic components 11 that they contact.

Description

Technical Field

[0001] The present invention relates to a circuit device that performs signal processing for a pressure detection device or the like installed in an internal combustion engine, and more particularly to a circuit device for improving operational stability under high-temperature and high-vibration environments.

Background Art

[0002] In a pressure detection device for controlling an internal combustion engine, for example a pressure detection device using a piezoelectric body as a pressure-sensitive element, the pressure of fuel combustion gas in the internal combustion engine can be directly measured by using a langatate single crystal as the piezoelectric body. The pressure detection device has a charge amplifier circuit that amplifies a charge of several picocoulombs per newton output by the langatate single crystal built in the device main body in response to pressure, converts the amplified charge into a voltage signal or a current signal, and transmits the signal to a control computer of the internal combustion engine. Patent Document 1 discloses that in a pressure sensor used for marine diesel engines and the like, mechanical resonance vibration of an electric circuit board (51) including an amplifier circuit is attenuated by reinforcing elements (52.1, 52.2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] Conventional pressure detection devices have had issues with operational stability in high-temperature and high-vibration environments. Specifically, in high-temperature environments such as internal combustion engines, electronic components mounted on circuit boards can become hot, potentially reducing the accuracy of signal processing. Furthermore, in high-vibration environments, circuit boards and electronic components are susceptible to damage due to vibration, leading to a decrease in the overall reliability of the device. This is particularly serious for pressure detection devices using piezoelectric materials, as they require accurate amplification and conversion of minute charge signals. Therefore, there is a need for circuit devices that can operate stably even in high-temperature and high-vibration environments, improving both signal processing accuracy and device reliability. [Means for solving the problem]

[0005] The circuit device comprises an elastic member that contacts the circuit board, the electronic components, and the housing, and dissipates heat from the electronic components to the housing. The elastic member may be a circuit device having a surface that conforms to the surface shape of the circuit board and the electronic component it is in contact with. Furthermore, the electronic components may include high-heat generating electronic components that generate a relatively large amount of heat on the circuit board and low-heat generating electronic components that generate a relatively small amount of heat, and the elastic member may be a circuit device that is arranged in contact with the high-heat generating components. Furthermore, the circuit board may have wiring connected to the electronic component, a GND path for the circuit board may be formed around the high-heat-generating component, and a heat dissipation section with a relatively large width for the wiring may be provided, and the heat dissipation section may be in contact with the elastic member. Furthermore, the elastic member may be a circuit device arranged on the front and back surfaces of the circuit board. Furthermore, the circuit device according to claim 1 may be characterized in that the elastic member is made of a composite material in which a filler having a higher thermal conductivity than the elastic material is dispersed in an elastic base material. Alternatively, the circuit device may have irregularities on the surface of the elastic member that contacts the housing. Furthermore, the aforementioned irregularities may be a circuit device having a plurality of protrusions and recesses that are horizontal to the short side of the circuit board. The circuit device may be configured such that a circuit board equipped with electronic components is housed in a housing, and an elastic member is provided that contacts the circuit board, the electronic components, and the housing to dissipate heat from the electronic components to the housing, the elastic member having a surface that conforms to the surface shape of the circuit board and the electronic components, the electronic components including high-heat generating electronic components and low-heat generating electronic components, the elastic member being positioned in contact with the high-heat generating components, the circuit board having wiring connected to the electronic components, the GND path of the circuit board being formed around the high-heat generating components, the wiring having a large heat dissipation section, the heat dissipation section being in contact with the elastic member, the elastic member being positioned on the front and back surfaces of the circuit board, the elastic member being a composite material in which alumina and aluminum nitride are dispersed in silicone rubber, and the surface in contact with the housing having irregularities, the irregularities having a plurality of protrusions and recesses that are horizontal to the short side of the circuit board. [Effects of the Invention]

[0006] According to the circuit device of the present invention, it is possible to provide a circuit device that enables extended lifespan and high-precision signal processing even when used in harsh environments such as internal combustion engines. [Brief explanation of the drawing]

[0007] [Figure 1] This is a top view of a circuit device according to one embodiment of the present invention, and is a view of the circuit board from one side. [Figure 2] This is a bottom view of a circuit device according to one embodiment of the present invention, and is a view from the other side of the circuit board. [Figure 3] This is a side view of a circuit device relating to one embodiment of the present invention. [Figure 4] This is an external view of a pressure detection device equipped with a circuit device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 4 is an external view of a pressure detection device 20 equipped with a circuit device 30 according to one embodiment of the present invention. The pressure detection device 20 comprises a pressure sensor body 14 that houses a piezoelectric single crystal and outputs a charge corresponding to the pressure received, a circuit device 30 that amplifies the charge output from the pressure sensor body 14, and a shielded cable 4 that connects the pressure sensor body 14 and the circuit device 30. The circuit device 30 comprises a cylindrical housing 13 that houses a circuit board 3 having a circuit for converting the charge signal from the pressure sensor body 14 into a current or voltage signal and amplifying it, a disc housing 8 that introduces the shielded cable 4 into the cylindrical housing 13 and closes one end of the cylindrical housing 13, and a connector 7 that outputs the amplified signal from the circuit device 30 to the outside, inputs power to operate the circuit device 30 to the circuit board and closes the other end of the cylindrical housing 13.

[0009] Figure 1 is a top view of the circuit device 30, viewed from one side of the circuit board. Figure 2 is a bottom view of the circuit device 30, viewed from the other side of the circuit board. Figure 3 is a side view of the circuit device 30. In Figures 1 to 3, the cylindrical housing 13 is removed from the circuit device 30 to explain its internal configuration. In Figures 1 and 2, the vibration-damping and heat-dissipating rubbers 1a and 1b are shown in perspective, and only a portion of the GND wiring pattern is shown for the purpose of explaining the heat dissipation sections 2 and 9 later. In Figure 3, only the vibration-damping and heat-dissipating rubbers 1a and 1b are shown in cross-sectional view.

[0010] The circuit board 3 is a circuit that processes the output signal from the pressure sensor body 14. For example, when the charge signal output from the pressure sensor body 14 is to be converted into a voltage signal, it consists of a charge amplifier that converts the charge signal from the pressure sensor body 14 into a voltage signal, and a buffer circuit connected to the charge amplifier, with multiple electronic components 11 mounted on it. If the output signal from the circuit device 30 is to be converted into a current signal, a configuration with a voltage-to-current conversion circuit (VI converter) between the charge amplifier and the buffer circuit may also be used.

[0011] The electronic components 11 are mounted on one side of the circuit board 3 (hereinafter referred to as "side A") and the other side opposite side A (hereinafter referred to as "side B"). The circuit board 3 has high-heat generating electronic components 11a and 11b, which generate relatively large amounts of heat, and low-heat generating components 11c, 11d, and 11e, which generate relatively small amounts of heat. The circuit board 3 also has wiring patterns that are connected to the electronic components 11 according to the circuit configuration. A portion of the wiring patterns around the high-heat generating components 11a and 11b that constitute the GND path of the circuit board 3 has a heat dissipation section 2 with a relatively larger wiring width compared to the other parts. Furthermore, side B, on the end side of the circuit board 3 where the L-shaped structure 10 described later is fixed, has a heat dissipation pattern 9 that is connected to the wiring patterns that constitute the GND path of the circuit board 3 and has a relatively larger area than the wiring patterns excluding the heat dissipation section 2.

[0012] An L-shaped structure 10 for fixing the disc housing 8 is fixed to one end of the circuit board 3. The L-shaped structure 10 has two orthogonal pieces, one of which has a screw hole and the other has a through hole. The circuit board 3 is mounted on one piece of the L-shaped structure 10 so that the heat dissipation pattern 9 on side B is in contact with it, and the circuit board 3 has a through hole at a position corresponding to the screw hole of the L-shaped structure 10. The circuit board 3 and the L-shaped structure 10 are fixed together by fastening them with screws through this screw hole and through hole. In the circuit device 30, the end on which the L-shaped structure 10 is attached is the side closer to the pressure sensor body 14, and the internal combustion engine to which the pressure sensor body 14 is attached becomes hot, so by keeping the L-shaped structure 10 in contact with the heat dissipation pattern 9, the heat transmitted from the shield cable 4 can be efficiently dissipated to the cylindrical housing 13.

[0013] A disc housing 8 is fixed to the other end of the L-shaped structure 10. The L-shaped structure 10 and the disc housing 8 are fixed together by screw fastening. Specifically, the L-shaped structure 10 and the disc housing 8 are fixed together by fastening screws through a through hole provided in the other end of the L-shaped structure 10 and a screw hole in the disc housing 8 located at a position corresponding to the through hole. The disc housing 8 is also provided with a through hole for inserting a shield cable 4. A waterproof and dustproof packing is provided between the inner wall of this through hole and the shield cable 4, and is configured to achieve IP67 sealing performance according to JIS-C-0920 and IEC-60529 standards.

[0014] The shield cable 4, which is introduced into the circuit board 3, is connected to the circuit board 3. Specifically, the core wire of the shield cable 4 is directly soldered to the charge receiving terminal 5 provided on one end of the circuit board 3. In addition, the braid of the shield cable 4 is connected and fixed to the GND path provided on the circuit board 3.

[0015] A circular circuit board 12 is connected to the other end of the circuit board 3 so as to be perpendicular to the electronic component mounting surfaces (sides A and B) of the circuit board 3. The circular circuit board 12 is a component that electrically connects the circuit board 3 and the connector 7, and the circular circuit board 12 and the circuit board 3 are connected to each other by soldering or the like without any separation between them. The connector 7 is connected to the side of the circular circuit board 12 opposite to the side to which the circuit board 3 is connected. The connector 7 is a connection part for signal output from the circuit board 3 and for supplying power to the circuit board 3 from an external source, and each terminal of the connector 7 is soldered to a wiring pattern provided on the circular circuit board 12, so that the wiring pattern of the circuit board 3 and each terminal of the connector 7 are electrically connected.

[0016] Then, the cylindrical housing 13 is connected to the outer peripheral portions of each of the disc housing 8 connected to the circuit board 3 via the L-shaped structure 10 and the connector 7 connected to the circuit board 3 via the circular board 12, so as to accommodate the circuit board 3 therein. At this time, the outer diameters of the disc housing 8 and the connector 7 are slightly smaller than the inner diameter of the cylindrical housing 13, and the disc housing 8 and the connector 7 are each fixed to the cylindrical housing 13 by adhesion, seam welding, or the like.

[0017] Further, vibration-proof and heat-dissipating rubbers 1a and 1b are arranged on the circuit board 3 and the electronic component 11 and inside the cylindrical housing 13. Each of the vibration-proof and heat-dissipating rubbers 1a and 1b is a semi-cylindrical member having a rectangular bottom surface and a top surface shaped to draw an arc along the long side of the bottom surface, is an elastic body excellent in vibration damping property that absorbs and attenuates vibration, and is formed of a composite material in which fillers (filling materials) of alumina and aluminum nitride having higher thermal conductivity than the base material are uniformly dispersed in a base material of silicone rubber having high thermal conductivity. Alumina improves the thermal conductivity of the base material silicone rubber, also relatively stabilizes the humidity resistance characteristics as an environmental stabilizer for the aluminum nitride dispersed together, and can achieve a longer service life of the circuit device 30.

[0018] Regarding the vibration-proof and heat-dissipating rubbers 1a and 1b, the vibration-proof and heat-dissipating rubber 1a is arranged on the A surface of the circuit board 3, and the vibration-proof and heat-dissipating rubber 1b is arranged on the B surface, with their respective bottom surfaces in contact with the circuit board 3 and the electronic component 11 mounted on the circuit board 3, and their respective top surfaces arranged to be in contact with the inner wall surface of the cylindrical housing 13. The vibration-proof and heat-dissipating rubbers 1a and 1b serve to suppress transmission of vibration applied from the outside of the circuit device 30 to the circuit board 3 (and the electronic component 11), and further to efficiently dissipate heat generated from the circuit board 3 and the electronic component 11 to the cylindrical housing 13.

[0019] In the present embodiment, vibration-proof and heat-dissipating rubbers 1a and 1b are arranged at a substantially central portion in the longitudinal direction of the circuit board 3. At this time, high-heat-generating electronic components 11a and 11b are mounted at the substantially central portion of the circuit board 3, and the vibration-proof and heat-dissipating rubbers 1a and 1b are arranged so as to cover the high-heat-generating electronic components 11a and 11b. In addition, a part of the heat dissipating portion 2 of the wiring pattern is also covered (in contact) with the vibration-proof and heat-dissipating rubbers 1a and 1b. The low-heat-generating electronic components 11c, 11d, and 11e are not covered by the vibration-proof and heat-dissipating rubbers 1a and 1b.

[0020] By arranging the vibration-proof and heat-dissipating rubbers 1a and 1b in this manner, the heat generated from the high-heat-generating electronic components 11a and 11b having a high calorific value can be efficiently dissipated to the cylindrical housing 13. In addition, the vibration of the circuit board 3 when external vibration is applied can be significantly suppressed. This is due to the vibration damping effect of the vibration-proof and heat-dissipating rubbers 1a and 1b, and the fact that by disposing the vibration-proof and heat-dissipating rubbers 1a and 1b at the substantially central portion of the circuit board 3, the resonance frequency of the circuit board 3 is approximately doubled compared to the case where the vibration-proof and heat-dissipating rubbers 1a and 1b are not disposed. This vibration suppression effect can be selected according to the externally applied vibration frequency, and for example, it is possible to cope with various vibration frequencies by changing the number and arrangement positions of the vibration-proof and heat-dissipating rubbers 1a and 1b. In this case, in order to obtain the heat dissipation effect of the vibration-proof and heat-dissipating rubbers 1a and 1b, it is preferable to appropriately lay out the vibration-proof and heat-dissipating rubbers 1a and 1b according to the mounting positions of the high-heat-generating electronic components 11a and 11b.

[0021] Furthermore, the bottom surfaces of the vibration-damping and heat-dissipating rubbers 1a and 1b in this embodiment have a shape that conforms to the surface shape of the circuit board 3, which includes the electronic components 11 on which they are placed. Specifically, the bottom surfaces of the vibration-damping and heat-dissipating rubbers 1a and 1b have a surface shape that includes a flat surface that contacts the circuit board 3 and recesses that substantially match the shape of the high-heat-generating electronic components 11a and 11b at positions corresponding to the high-heat-generating electronic components 11a and 11b covered by the vibration-damping and heat-dissipating rubbers 1a and 1b. This is to prevent the high-heat-generating electronic components 11a and 11b from receiving excessive pressure from the vibration-damping and heat-dissipating rubbers 1a and 1b. However, it is preferable that the vibration-damping and heat-dissipating rubbers 1a and 1b are sandwiched between the circuit board 3 and the cylindrical housing 13 with a predetermined pressure to ensure contact between the circuit board 3 and the high-heat-generating electronic components 11a and 11b.

[0022] Furthermore, the upper surfaces of the vibration-damping and heat-dissipating rubbers 1a and 1b in this embodiment have multiple protrusions and recesses that are horizontal to the short side of the circuit board 3. This shape reduces the contact resistance between the circuit board 3 and the vibration-damping and heat-dissipating rubbers 1a and 1b when they are placed in the cylindrical housing 13, thereby improving the ease of assembly of the circuit device 30.

[0023] Although the circuit device of the present invention has been described above based on one embodiment, the present invention is not limited to this embodiment. For example, although an example was shown in which a composite material in which alumina filler is dispersed in a silicone rubber base material was used as the vibration-damping and heat-dissipating rubber 1a, 1b, the base material of the vibration-damping and heat-dissipating rubber 1a, 1b may be made of an elastic material such as an elastomer in addition to silicone rubber. By making the vibration-damping and heat-dissipating rubber 1a, 1b from an elastic material, the adhesion to the high heat-generating electronic components 11a, 11b, the circuit board 3 and the cylindrical housing 13 is improved, and the shape-following ability to these components can also be improved. Furthermore, vibration energy can be absorbed and vibration of the amplifier circuit board 3 can be efficiently suppressed, thereby preventing damage to the electronic components 11 and the circuit board 3 due to vibration and extending the lifespan of the circuit device 30.

[0024] Furthermore, vibration-damping and heat-dissipating rubbers 1a and 1b can be made to have high heat dissipation by including a filler with high thermal conductivity in the elastic material base. In addition to alumina and aluminum nitride, insulating inorganic materials with high thermal conductivity such as boron nitride or magnesium oxide can be used as fillers. It is also possible to have a configuration in which no filler is included in the elastic material base, such as silicone rubber. [Explanation of Symbols]

[0025] 1a Vibration-damping and heat-dissipating rubber 1b Vibration-damping and heat-dissipating rubber 2 Heat dissipation part 3 Circuit board 4 Shielded Cables 5 Charge receiving terminals 7 Connectors 8-inch disc enclosure 9 Heat dissipation patterns 10 L-shaped structure 11 Electronic Components 11a High-heat generating electronic components 11b High-heat generating electronic components 11c Low Heat Generation Electronic Components 11d Low heat generation electronic components 11e Low-heat electronic components 12 circular circuit boards 13 Cylindrical housing 14. Pressure sensor body 20 Pressure detection device 30 Circuit equipment

Claims

1. In a circuit device in which a circuit board equipped with electronic components is housed in a casing, A circuit device characterized by comprising an elastic member that contacts the circuit board, the electronic component, and the housing, and dissipates heat from the electronic component to the housing.

2. The circuit device according to claim 1, characterized in that the elastic member has a surface that conforms to the surface shape of the circuit board and the electronic component that it contacts.

3. The circuit device according to claim 1 or 2, wherein the electronic components include a high-heat generating electronic component that generates a relatively large amount of heat on the circuit board and a low-heat generating electronic component that generates a relatively small amount of heat, and the elastic member is arranged in contact with the high-heat generating component.

4. The circuit device according to claim 3, wherein the circuit board has wiring connected to the electronic component, and the area around the high-heat generating component has a heat dissipation section that forms a GND path for the circuit board and has a relatively large width for the wiring, and the heat dissipation section is in contact with the elastic member.

5. The circuit device according to claim 1, characterized in that the elastic member is arranged on the front and back surfaces of the circuit board.

6. The circuit device according to claim 1, characterized in that the elastic member is made of a composite material in which a filler having a higher thermal conductivity than the elastic material is dispersed in a base material of the elastic material.

7. The circuit device according to claim 1, characterized in that the surface of the elastic member in contact with the housing has irregularities.

8. The circuit device according to claim 7, characterized in that the aforementioned irregularities have a plurality of protrusions and recesses that are horizontal to the short direction of the circuit board.

9. A circuit device comprising a circuit board on which electronic components are mounted, housed in a housing, and an elastic member that contacts the circuit board, the electronic components, and the housing to dissipate heat from the electronic components to the housing, wherein the elastic member has a surface that conforms to the surface shape of the circuit board and the electronic components, the electronic components include high-heat generating electronic components and low-heat generating electronic components, the elastic member is positioned in contact with the high-heat generating components, the circuit board has wiring connected to the electronic components, the circuit board has a GND path around the high-heat generating components, the wiring has a large heat dissipation section, the heat dissipation section is in contact with the elastic member, the elastic member is positioned on the front and back surfaces of the circuit board, the elastic member is a composite material in which alumina and aluminum nitride are dispersed in silicone rubber, and the surface that contacts the housing has irregularities, the irregularities having a plurality of convex and concave portions horizontal to the short-side direction of the circuit board.

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